Ana Rodriguez, Ph.D.

Activity In Vivo of Anti-Trypanosoma cruzi Compounds Selected from a High Throughput Screening
Andriani, Grasiella; Chessler, Anne-Danielle C; Courtemanche, Gilles; Burleigh, Barbara A; Rodriguez, Ana
2011 Aug;5(8):e1298-e1298, PLoS neglected tropical diseases
Novel technologies that include recombinant pathogens and rapid detection methods are contributing to the development of drugs for neglected diseases. Recently, the results from the first high throughput screening (HTS) to test compounds for activity against Trypanosoma cruzi trypomastigote infection of host cells were reported. We have selected 23 compounds from the hits of this HTS, which were reported to have high anti-trypanosomal activity and low toxicity to host cells. These compounds were highly purified and their structures confirmed by HPLC/mass spectrometry. The compounds were tested in vitro, where about half of them confirmed the anti-T. cruzi activity reported in the HTS, with IC50 values lower than 5 microM. We have also adapted a rapid assay to test anti-T. cruzi compounds in vivo using mice infected with transgenic T. cruzi expressing luciferase as a model for acute infection. The compounds that were active in vitro were also tested in vivo using this assay, where we found two related compounds with a similar structure and low in vitro IC50 values (0.11 and 0.07 microM) that reduce T. cruzi infection in the mouse model more than 90% after five days of treatment. Our findings evidence the benefits of novel technologies, such as HTS, for the drug discovery pathway of neglected diseases, but also caution about the need to confirm the results in vitro. We also show how rapid methods of in vivo screening based in luciferase-expressing parasites can be very useful to prioritize compounds early in the chain of development
— id: 137455, year: 2011, vol: 5, page: e1298, stat: Journal Article,

The Susceptibility of Trypanosomatid Pathogens to PI3/mTOR Kinase Inhibitors Affords a New Opportunity for Drug Repurposing
Diaz-Gonzalez, Rosario; Kuhlmann, F Matthew; Galan-Rodriguez, Cristina; Madeira da Silva, Luciana; Saldivia, Manuel; Karver, Caitlin E; Rodriguez, Ana; Beverley, Stephen M; Navarro, Miguel; Pollastri, Michael P
2011 Aug;5(8):e1297-e1297, PLoS neglected tropical diseases
BACKGROUND: Target repurposing utilizes knowledge of 'druggable' targets obtained in one organism and exploits this information to pursue new potential drug targets in other organisms. Here we describe such studies to evaluate whether inhibitors targeting the kinase domain of the mammalian Target of Rapamycin (mTOR) and human phosphoinositide-3-kinases (PI3Ks) show promise against the kinetoplastid parasites Trypanosoma brucei, T. cruzi, Leishmania major, and L. donovani. The genomes of trypanosomatids encode at least 12 proteins belonging to the PI3K protein superfamily, some of which are unique to parasites. Moreover, the shared PI3Ks differ greatly in sequence from those of the human host, thereby providing opportunities for selective inhibition. METHODOLOGY/PRINCIPAL FINDINGS: We focused on 8 inhibitors targeting mTOR and/or PI3Ks selected from various stages of pre-clinical and clinical development, and tested them against in vitro parasite cultures and in vivo models of infection. Several inhibitors showed micromolar or better efficacy against these organisms in culture. One compound, NVP-BEZ235, displayed sub-nanomolar potency, efficacy against cultured parasites, and an ability to clear parasitemia in an animal model of T. brucei rhodesiense infection. CONCLUSIONS/SIGNIFICANCE: These studies strongly suggest that mammalian PI3/TOR kinase inhibitors are a productive starting point for anti-trypanosomal drug discovery. Our data suggest that NVP-BEZ235, an advanced clinical candidate against solid tumors, merits further investigation as an agent for treating African sleeping sickness
— id: 137866, year: 2011, vol: 5, page: e1297, stat: Journal Article,

Identification of small-molecule inhibitors of Trypansoma cruzi replication
Germain, Andrew R; Carmody, Leigh C; Dockendorff, Chris; Galan-Rodriguez, Cristina; Rodriguez, Ana; Johnston, Stephen; Bittker, Joshua A; MacPherson, Lawrence; Dandapani, Sivaraman; Palmer, Michelle; Schreiber, Stuart L; Munoz, Benito
2011 Dec 1;21(23):7197-7200, Bioorganic & medicinal chemistry letters
We report the outcome of a high-throughput small-molecule screen to identify novel, nontoxic, inhibitors of Trypansoma cruzi, as potential starting points for therapeutics to treat for both the acute and chronic stages of Chagas disease. Two compounds were identified that displayed nanomolar inhibition of T. cruzi and an absence of activity against host cells at the highest tested dose. These compounds have been registered with NIH Molecular Libraries Program (probes ML157 and ML158)
— id: 146227, year: 2011, vol: 21, page: 7197, stat: Journal Article,

Color capable sub-pixel resolving optofluidic microscope and its application to blood cell imaging for malaria diagnosis
Lee, Seung Ah; Leitao, Ricardo; Zheng, Guoan; Yang, Samuel; Rodriguez, Ana; Yang, Changhuei
2011 ;6(10):e26127-e26127, PLoS ONE
Miniaturization of imaging systems can significantly benefit clinical diagnosis in challenging environments, where access to physicians and good equipment can be limited. Sub-pixel resolving optofluidic microscope (SROFM) offers high-resolution imaging in the form of an on-chip device, with the combination of microfluidics and inexpensive CMOS image sensors. In this work, we report on the implementation of color SROFM prototypes with a demonstrated optical resolution of 0.66 microm at their highest acuity. We applied the prototypes to perform color imaging of red blood cells (RBCs) infected with Plasmodium falciparum, a particularly harmful type of malaria parasites and one of the major causes of death in the developing world
— id: 139774, year: 2011, vol: 6, page: e26127, stat: Journal Article,

Daily Plasmodium yoelii infective mosquito bites do not generate protection or suppress previous immunity against the liver stage
Pollock, Tzvi; Leitao, Ricardo; Galan-Rodriguez, Cristina; Wong, Kurt A; Rodriguez, Ana
2011 ;10:97-97, Malaria journal
ABSTRACT: BACKGROUND: Human populations that are naturally subjected to Plasmodium infection do not acquire complete protection against the liver stage of this parasite despite prolonged and frequent exposure. However, sterile immunity against Plasmodium liver stage can be achieved after repeated exposure to radiation attenuated sporozoites. The reasons for this different response remain largely unknown, but a suppressive effect of blood stage Plasmodium infection has been proposed as a cause for the lack of liver stage protection. METHODS: Using Plasmodium yoelii 17XNL, the response generated in mice subjected to daily infective bites from normal or irradiated mosquitoes was compared. The effect of daily-infected mosquito bites on mice that were previously immunized against P. yoelii liver stage was also studied. RESULTS: It was observed that while the bites of normal infected mosquitoes do not generate strong antibody responses and protection, the bites of irradiated mosquitoes result in high levels of anti-sporozoite antibodies and protection against liver stage Plasmodium infection. Exposure to daily infected mosquito bites did not eliminate the protection acquired previously with a experimental liver stage vaccine. CONCLUSIONS: Liver stage immunity generated by irradiated versus normal P. yoelii infected mosquitoes is essentially different, probably because of the blood stage infection that follows normal mosquito bites, but not irradiated. While infective mosquito bites do not induce a protective liver stage response, they also do not interfere with previously acquired liver stage protective responses, even if they induce a complete blood stage infection. Considering that the recently generated anti-malaria vaccines induce only partial protection against infection, it is encouraging that, at least in mouse models, immunity is not negatively affected by subsequent exposure and infection with the parasite
— id: 133322, year: 2011, vol: 10, page: 97, stat: Journal Article,

The crucial role of hepatocyte growth factor receptor during liver-stage infection is not conserved among Plasmodium species
Rodriguez, Ana; Mota, Maria M
2011 ;17(10):1181-1181, Nature medicine
— id: 138714, year: 2011, vol: 17, page: 1181, stat: Journal Article,

Efficient phagosomal maturation and degradation of Plasmodium-infected erythrocytes by dendritic cells and macrophages
Bettiol, E; Van de Hoef, D L; Carapau, D; Rodriguez, A
2010 Jun;32(6):389-398, Parasite immunology
Dendritic cells (DC) and macrophages phagocytose pathogens and degrade them in their phagosomes to allow for proper presentation of foreign antigens to other cells of the immune system. The Plasmodium parasite, causative agent of malaria, infects RBC that are phagocytosed by DC and macrophages during the course of infection. Under specific conditions, the functionality of these cells can be affected by phagocytosis of Plasmodium-infected RBC. We investigated whether phagosomal maturation and degradation of Plasmodium yoelii-infected RBC in phagosomes is affected in DC and macrophages. We show that recruitment of the phagolysosomal marker Lamp-1 and of MHC-II, as well as acidification of phagosomes, was achieved in a timely manner. Using P. yoelii-infected RBC labelled with a fluorescent dye or transgenic green fluorescent protein (GFP)-expressing parasites, we found a gradual, rapid decrease in the phagosome fluorescence signal, indicating that P. yoelii-infected RBC are efficiently degraded in macrophages and DC. We also observed that pre-incubation of DC with infected RBC did not affect phagosomal maturation of newly internalized P. yoelii-infected RBC. In conclusion, after phagocytosis, Plasmodium-infected RBC are degraded by DC and macrophages, suggesting that the process of phagosomal maturation is effectively completed in malaria
— id: 109809, year: 2010, vol: 32, page: 389, stat: Journal Article,

Dual effect of Plasmodium-infected erythrocytes on dendritic cell maturation
Bettiol, Esther; Carapau, Daniel; Galan-Rodriguez, Cristina; Ocana-Morgner, Carlos; Rodriguez, Ana
2010 ;9:64-64, Malaria journal
BACKGROUND: Infection with Plasmodium is the cause of malaria, a disease characterized by a high inflammatory response in the blood. Dendritic cells (DC) participate in both adaptive and innate immune responses, influencing the generation of inflammatory responses. DC can be activated through different receptors, which recognize specific molecules in microbes and induce the maturation of DC. METHODS: Using Plasmodium yoelii, a rodent malaria model, the effect of Plasmodium-infected erythrocytes on DC maturation and TLR responses have been analysed. RESULTS: It was found that intact erythrocytes infected with P. yoelii do not induce maturation of DC unless they are lysed, suggesting that accessibility of parasite inflammatory molecules to their receptors is a key issue in the activation of DC by P. yoelii. This activation is independent of MyD88. It was also observed that pre-incubation of DC with intact P. yoelii-infected erythrocytes inhibits the maturation response of DC to other TLR stimuli. The inhibition of maturation of DC is reversible, parasite-specific and increases with the stage of parasite development, with complete inhibition induced by schizonts (mature infected erythrocytes). Plasmodium yoelii-infected erythrocytes induce a broad inhibitory effect rendering DC non-responsive to ligands for TLR2, TLR3, TLR4, TLR5, TLR7 and TLR9. CONCLUSIONS: Despite the presence of inflammatory molecules within Plasmodium-infected erythrocytes, which are probably responsible for DC maturation induced by lysates, intact Plasmodium-infected erythrocytes induce a general inhibition of TLR responsiveness in DC. The observed effect on DC could play an important role in the pathology and suboptimal immune response observed during the disease. These results help to explain why immune functions are altered during malaria, and provide a system for the identification of a parasite-derived broad inhibitor of TLR-mediated signaling pathways
— id: 108794, year: 2010, vol: 9, page: 64, stat: Journal Article,

Inhibition of Plasmodium sporozoites infection by targeting the host cell
Leitao, Ricardo; Rodriguez, Ana
2010 Oct;126(2):273-277, Experimental parasitology
There is a great need of new drugs against malaria because of the increasing spread of parasite resistance against the most commonly used drugs in the field. We found that monensin, a common veterinary antibiotic, has a strong inhibitory effect in Plasmodium berghei and Plasmodium yoelii sporozoites hepatocyte infection in vitro. Infection of host cells by another apicomplexan parasite with a similar mechanism of host cell invasion, Toxoplasma tachyzoites, was also inhibited. Treatment of mice with monensin abrogates liver infection with P. berghei sporozoites in vivo. We also found that at low concentrations monensin inhibits the infection of Plasmodium sporozoites by rendering host cells resistant to infection, rather than having a direct effect on sporozoites. Monensin effect is targeted to the initial stages of parasite invasion of the host cell with little or no effect on development, suggesting that this antibiotic affects an essential host cell component that is required for Plasmodium sporozoite invasion
— id: 111583, year: 2010, vol: 126, page: 273, stat: Journal Article,

A putative kinase-related protein (PKRP) from Plasmodium berghei mediates infection in the midgut and salivary glands of the mosquito
Purcell, Lisa A; Leitao, Ricardo; Ono, Takeshi; Yanow, Stephanie K; Pradel, Gabriele; Spithill, Terry W; Rodriguez, Ana
2010 Jul;40(8):979-988, International journal for parasitology
The completion of the Plasmodium (malaria) life cycle in the mosquito requires the parasite to traverse first the midgut and later the salivary gland epithelium. We have identified a putative kinase-related protein (PKRP) that is predicted to be an atypical protein kinase, which is conserved across many species of Plasmodium. The pkrp gene encodes a RNA of about 5300 nucleotides that is expressed as a 90kDa protein in sporozoites. Targeted disruption of the pkrp gene in Plasmodium berghei, a rodent model of malaria, compromises the ability of parasites to infect different tissues within the mosquito host. Early infection of mosquito midgut is reduced by 58-71%, midgut oocyst production is reduced by 50-90% and those sporozoites that are produced are defective in their ability to invade mosquito salivary glands. Midgut sporozoites are not morphologically different from wild-type parasites by electron microscopy. Some sporozoites that emerged from oocysts were attached to the salivary glands but most were found circulating in the mosquito hemocoel. Our findings indicate that a signalling pathway involving PbPKRP regulates the level of Plasmodium infection in the mosquito midgut and salivary glands
— id: 133509, year: 2010, vol: 40, page: 979, stat: Journal Article,

Experimental cerebral malaria progresses independently of the Nlrp3 inflammasome
Reimer, Thornik; Shaw, Michael H; Franchi, Luigi; Coban, Cevayir; Ishii, Ken J; Akira, Shizuo; Horii, Toshihiro; Rodriguez, Ana; Nunez, Gabriel
2010 Mar;40(3):764-769, European journal of immunology
Cerebral malaria is the most severe complication of Plasmodium falciparum infection in humans and the pathogenesis is still unclear. Using the P. berghei ANKA infection model of mice, we investigated a potential involvement of Nlrp3 and the inflammasome in the pathogenesis of cerebral malaria. Nlrp3 mRNA expression was upregulated in brain endothelial cells after exposure to P. berghei ANKA. Although beta-hematin, a synthetic compound of the parasites heme polymer hemozoin, induced the release of IL-1beta in macrophages through Nlrp3, we did not obtain evidence for a role of IL-1beta in vivo. Nlrp3 knock-out mice displayed a delayed onset of cerebral malaria; however, mice deficient in caspase-1, the adaptor protein ASC or the IL-1 receptor succumbed as WT mice. These results indicate that the role of Nlrp3 in experimental cerebral malaria is independent of the inflammasome and the IL-1 receptor pathway
— id: 133483, year: 2010, vol: 40, page: 764, stat: Journal Article,

Identification of Three Classes of Heteroaromatic Compounds with Activity against Intracellular Trypanosoma cruzi by Chemical Library Screening
Bettiol, Esther; Samanovic, Marie; Murkin, Andrew S; Raper, Jayne; Buckner, Frederick; Rodriguez, Ana
2009 ;3(2):e384-e384, PLoS neglected tropical diseases
The development of new drugs against Chagas disease is a priority since the currently available medicines have toxic effects, partial efficacy and are targeted against the acute phase of disease. At present, there is no drug to treat the chronic stage. In this study, we have optimized a whole cell-based assay for high throughput screening of compounds that inhibit infection of mammalian cells by Trypanosoma cruzi trypomastigotes. A 2000-compound chemical library was screened using a recombinant T. cruzi (Tulahuen strain) expressing beta-galactosidase. Three hits were selected for their high activity against T. cruzi and low toxicity to host cells in vitro: PCH1, NT1 and CX1 (IC(50): 54, 190 and 23 nM, respectively). Each of these three compounds presents a different mechanism of action on intracellular proliferation of T. cruzi amastigotes. CX1 shows strong trypanocidal activity, an essential characteristic for the development of drugs against the chronic stage of Chagas disease where parasites are found intracellular in a quiescent stage. NT1 has a trypanostatic effect, while PCH1 affects parasite division. The three compounds also show high activity against intracellular T. cruzi from the Y strain and against the related kinetoplastid species Leishmania major and L. amazonensis. Characterization of the anti-T. cruzi activity of molecules chemically related to the three library hits allowed the selection of two compounds with IC(50) values of 2 nM (PCH6 and CX2). These values are approximately 100 times lower than those of the medicines used in patients against T. cruzi. These results provide new candidate molecules for the development of treatments against Chagas disease and leishmaniasis
— id: 96764, year: 2009, vol: 3, page: e384, stat: Journal Article,

Uric acid is a mediator of the Plasmodium falciparum-induced inflammatory response
Orengo, Jamie Marie; Leliwa-Sytek, Aleksandra; Evans, James E; Evans, Barbara; van de Hoef, Diana; Nyako, Marian; Day, Karen; Rodriguez, Ana
2009 ;4(4):e5194-e5194, PLoS ONE
BACKGROUND: Malaria triggers a high inflammatory response in the host that mediates most of the associated pathologies and contributes to death. The identification of pro-inflammatory molecules derived from Plasmodium is essential to understand the mechanisms of pathogenesis and to develop targeted interventions. Uric acid derived from hypoxanthine accumulated in infected erythrocytes has been recently proposed as a mediator of inflammation in rodent malaria. METHODS AND FINDINGS: We found that human erythrocytes infected with Plasmodium falciparum gradually accumulate hypoxanthine in their late stages of development. To analyze the role of hypoxanthine-derived uric acid induced by P. falciparum on the inflammatory cytokine response from human blood mononuclear cells, cultures were treated with allopurinol, to inhibit uric acid formation from hypoxanthine, or with uricase, to degrade uric acid. Both treatments significantly reduce the secretion of TNF, IL-6, IL-1beta and IL-10 from human cells. CONCLUSIONS AND SIGNIFICANCE: Uric acid is a major contributor of the inflammatory response triggered by P. falciparum in human peripheral blood mononuclear cells. Since the inflammatory reaction induced by P. falciparum is considered a major cause of malaria pathogenesis, identifying the mechanisms used by the parasite to induce the host inflammatory response is essential to develop urgently needed therapies against this disease
— id: 99008, year: 2009, vol: 4, page: e5194, stat: Journal Article,

New pieces for the malaria liver stage puzzle: where will they fit?
Mota, Maria M; Rodriguez, Ana
2008 Feb 14;3(2):63-65, Cell Host & Microbe
Malaria starts with the infection of the liver by Plasmodium parasites. Although extensive analysis of Plasmodium has revealed the expression patterns of this parasite in every stage of its life cycle, the liver stage remained unexplored. Recently, Tarun et al. have published the first complete transcriptome and proteome analysis of this intriguing parasite stage, providing a list of potential candidate target genes for antimalarial vaccines and drugs
— id: 78879, year: 2008, vol: 3, page: 63, stat: Journal Article,

Interactions between dendritic cells and CD4+ T cells during Plasmodium infection
Ocana-Morgner, Carlos; Wong, Kurt A; Rodriguez, Ana
2008 May 21;7(1):88-88, Malaria journal
ABSTRACT: BACKGROUND: During infection, dendritic cells (DCs) encounter pathogenic microorganisms that can modulate their function and shape the T cell responses generated. During the process of T cell activation, DCs normally establish strong, long-lasting interactions with naive T cells. METHODS: Using a mouse malaria model, the interactions of DCs and naive CD4+ T cells have been analysed. RESULTS: DCs, either incubated in vitro with infected erythrocytes or isolated from infected mice, are able to present exogenous antigens by MHC-II, but are not able to establish prolonged effective interactions with naive CD4+ T cells and do not induce T cell activation. It was also found that effective T cell activation of naive CD4+ T cells is impaired during late Plasmodium yoelii infection. CONCLUSION: These data may provide a mechanism for the lack of effective adaptive immune responses induced by the Plasmodium parasite
— id: 78878, year: 2008, vol: 7, page: 88, stat: Journal Article,

Adenylyl cyclase alpha and cAMP signaling mediate Plasmodium sporozoite apical regulated exocytosis and hepatocyte infection
Ono, Takeshi; Cabrita-Santos, Laura; Leitao, Ricardo; Bettiol, Esther; Purcell, Lisa A; Diaz-Pulido, Olga; Andrews, Lucy B; Tadakuma, Takushi; Bhanot, Purnima; Mota, Maria M; Rodriguez, Ana
2008 ;4(2):e1000008-e1000008, PLoS pathogens
Malaria starts with the infection of the liver of the host by Plasmodium sporozoites, the parasite form transmitted by infected mosquitoes. Sporozoites migrate through several hepatocytes by breaching their plasma membranes before finally infecting one with the formation of an internalization vacuole. Migration through host cells induces apical regulated exocytosis in sporozoites. Here we show that apical regulated exocytosis is induced by increases in cAMP in sporozoites of rodent (P. yoelii and P. berghei) and human (P. falciparum) Plasmodium species. We have generated P. berghei parasites deficient in adenylyl cyclase alpha (ACalpha), a gene containing regions with high homology to adenylyl cyclases. PbACalpha-deficient sporozoites do not exocytose in response to migration through host cells and present more than 50% impaired hepatocyte infectivity in vivo. These effects are specific to ACalpha, as re-introduction of ACalpha in deficient parasites resulted in complete recovery of exocytosis and infection. Our findings indicate that ACalpha and increases in cAMP levels are required for sporozoite apical regulated exocytosis, which is involved in sporozoite infection of hepatocytes
— id: 78696, year: 2008, vol: 4, page: e1000008, stat: Journal Article,

Plasmodium-induced inflammation by uric acid
Orengo, Jamie M; Evans, James E; Bettiol, Esther; Leliwa-Sytek, Aleksandra; Day, Karen; Rodriguez, Ana
2008 Mar;4(3):e1000013-e1000013, PLoS pathogens
Infection of erythrocytes with the Plasmodium parasite causes the pathologies associated with malaria, which result in at least one million deaths annually. The rupture of infected erythrocytes triggers an inflammatory response, which is induced by parasite-derived factors that still are not fully characterized. Induced secretion of inflammatory cytokines by these factors is considered a major cause of malaria pathogenesis. In particular, the inflammatory cytokine tumor necrosis factor (TNF) is thought to mediate most of the life-threatening pathologies of the disease. Here we describe the molecular characterization of a novel pathway that results in the secretion of TNF by host cells. We found that erythrocytes infected by Plasmodium accumulate high concentrations of hypoxanthine and xanthine. Degradation of Plasmodium-derived hypoxanthine/xanthine results in the formation of uric acid, which triggers the secretion of TNF. Since uric acid is considered a 'danger signal' released by dying cells to alert the immune system, Plasmodium appears to have co-evolved to exploit this warning system. Identifying the mechanisms used by the parasite to induce the host inflammatory response is essential to develop urgently needed therapies against this disease
— id: 78762, year: 2008, vol: 4, page: e1000013, stat: Journal Article,

A Plasmodium yoelii soluble factor inhibits the phenotypic maturation of dendritic cells
Orengo, Jamie M; Wong, Kurt A; Ocana-Morgner, Carlos; Rodriguez, Ana
2008 ;7:254-254, Malaria journal
BACKGROUND: Infection with the protozoan parasite Plasmodium is the cause of malaria. Plasmodium infects host erythrocytes causing the pathology of the disease. Plasmodium-infected erythrocytes can modulate the maturation of dendritic cells (DCs) and alter their capacity to activate T cells. METHODS: Mice infected with Plasmodium yoelii and isolated P. yoelii-infected erythrocytes were used to study their effect on the maturation of mouse dendritic cells. RESULTS: DCs are not able to mature in response to LPS injection during the late stage of P. yoelii infection in mice, indicating impaired functionality of these cells in vivo. P. yoelii- infected erythrocytes inhibit the maturation of DCs in vitro in a dose-dependent manner, which is consistent with the inhibition found during late infection when parasite burden is highest. The inhibition of DC maturation and the cytokine secretion profile of DCs are modulated by soluble factors released by P. yoelii-infected erythrocytes. A small, heat-stable, non-hydrophobic molecule of P. yoelii-infected erythrocytes rapidly inhibits the LPS induced phenotypic maturation of DCs in a reversible manner. CONCLUSION: These findings add evidence to the malaria associated immune suppression in vivo and in vitro and provide insight into the nature and mechanism of the Plasmodium factor(s) responsible for altering DC functions
— id: 92141, year: 2008, vol: 7, page: 254, stat: Journal Article,

Chemically attenuated Plasmodium sporozoites induce specific immune responses, sterile immunity and cross-protection against heterologous challenge
Purcell, LA; Wong, KA; Yanow, SK; Lee, M; Spithill, TW; Rodriguez, A
2008 SEP 8 ;26(38):4880-4884, Vaccine
Vaccination with Plastriodium sporozoites attenuated by irradiation or genetic manipulation induces a protective immune response in rodent malaria models. Recently, vaccination with chemically attenuated P. berghei sporozoites (CAS) has also been shown to elicit sterile immunity in mice. Here we show that vaccination with CAS of P. yoelii also protects against homologous infection and that a P. berghei CAS vaccine cross protects against heterologous challenge with P. yoelii sporozoites. Vaccination with P. yoelii or P. berghei CAS induced parasite-specific antibodies and IFN-gamma-producing CD8(+) T cells at levels not significantly different from radiation-attenuated sporozoites. Our findings provide an initial characterization of the immune response generated by CAS vaccination and Suggest that this attenuation process could be used in the production of an effective cross-protective liver stage vaccine for malaria. (C) 2008 Elsevier Ltd. All rights reserved
— id: 89372, year: 2008, vol: 26, page: 4880, stat: Journal Article,

Chemical attenuation of Plasmodium berghei sporozoites induces sterile immunity in mice
Purcell, Lisa A; Yanow, Stephanie K; Lee, Moses; Spithill, Terry W; Rodriguez, Ana
2008 Mar;76(3):1193-1199, Infection & immunity
Radiation or genetic attenuation of Plasmodium sporozoites are two approaches for whole organism vaccines that are protective against malaria. We evaluated chemical attenuation of sporozoites as an alternative vaccine strategy. Sporozoites were treated with the DNA sequence-specific alkylating agent centanamycin, a compound that significantly affects blood stage parasitemia and transmission of murine malaria and also inhibits P. falciparum growth in vitro. Here, we show that treatment of P. berghei sporozoites with centanamycin impaired parasite function both in vitro and in vivo. Infectivity of hepatocytes by sporozoites in vitro was significantly reduced and treated parasites showed arrested liver stage development. Inoculation of mice with sporozoites that were treated in vitro with centanamycin failed to produce blood stage infections. Furthermore, BALB/c and C57/BL6 mice vaccinated with treated sporozoites were protected against subsequent challenge with wild type sporozoites. Our findings demonstrate that chemically attenuated sporozoites (CAS) could be a viable alternative for the production of an effective liver stage vaccine for malaria
— id: 75704, year: 2008, vol: 76, page: 1193, stat: Journal Article,

Plasmodium infection and endotoxic shock induce the expansion of regulatory dendritic cells
Wong, Kurt A; Rodriguez, Ana
2008 Jan 15;180(2):716-726, Journal of immunology
During an acute Plasmodium infection, uncontrolled proinflammatory responses can cause morbidity and mortality. Regulation of this response is required to prevent immunopathology. We therefore decided to investigate a recently characterized subset of regulatory dendritic cells (DCs) that expresses low levels of CD11c and high levels of CD45RB. During a Plasmodium yoelii infection, these regulatory CD11c(low)CD45RB(high) DCs become the prevalent CD11c-expressing cells in the spleen, overtaking the conventional CD11c(high) DCs. Furthermore, the regulatory CD11c(low)CD45RB(high) DCs induce IL-10-expressing CD4 T cells. A similar change in splenic DC subsets is seen when mice are injected with sublethal doses of LPS, suggesting that shifting the splenic DC subsets in favor of regulatory CD11c(low)CD45RB(high) DCs can be triggered solely by a high inflammatory stimulus. This is the first time regulatory DCs have been observed in a natural immune response to an infectious disease or endotoxic shock
— id: 75703, year: 2008, vol: 180, page: 716, stat: Journal Article,

Potent antimalarial and transmission-blocking activities of centanamycin, a novel DNA-binding agent
Yanow, Stephanie K; Purcell, Lisa A; Pradel, Gabriele; Sato, Atsushi; Rodriguez, Ana; Lee, Moses; Spithill, Terry W
2008 Feb 15;197(4):527-534, Journal of infectious diseases
Most treatments for malaria target the blood stage of infection in the human host, although few can also block transmission of the parasite to the mosquito. We show here that the compound centanamycin is very effective against blood-stage malarial infections in vitro and in vivo and has profound effects on sexual differentiation of the parasites in mosquitoes. After drug treatment, parasite development is arrested within the midguts of mosquitoes, failing to produce the infective forms that migrate to the salivary glands. The mechanism of parasite death is associated with modification of Plasmodium genomic DNA. We detected DNA damage in parasites isolated from mice 24 h after treatment with centanamycin, and, importantly, we also detected this DNA damage in parasites within mosquitoes that had fed on these mice 10 days earlier. This demonstrates that damage to parasite DNA during blood-stage infection persists from the vertebrate to the mosquito host and provides a novel biochemical strategy to block malaria transmission
— id: 78880, year: 2008, vol: 197, page: 527, stat: Journal Article,

Transcriptome profile of dendritic cells during malaria: cAMP regulation of IL-6
Carapau, Daniel; Kruhofer, Mogens; Chatalbash, Allison; Orengo, Jamie Marie; Mota, Maria Manuel; Rodriguez, Ana
2007 Jul;9(7):1738-1752, Cellular microbiology
Dendritic cells (DCs) have been proposed as mediators of immunity against malaria parasites, as well as a target for inhibition of cellular responses. Here we describe the transcriptomic analysis of spleen DCs in response to Plasmodium infection in a rodent model. We identified a high number of unique transcripts modulated in DCs upon infection. Many cellular functions suffer extensive genomic regulation including the cell cycle, the glycolysis and purine metabolism pathways and also defence responses. Only a small fraction of the regulated genes are coincident with the response induced by other pathogens, suggesting that Plasmodium induces a unique genetic re-programming of DCs. We confirmed regulation of a number of cytokines at the mRNA level including IL-6, IL-10 and IFN-gamma. We further dissected a signalling pathway regulating Plasmodium-induced expression of IL-6 by DCs, which is mediated by release of PGE2, increases in intracellular cAMP and activation of PKA and p38-MAPK
— id: 73576, year: 2007, vol: 9, page: 1738, stat: Journal Article,

Efficient development of plasmodium liver stage-specific memory CD8+ T cells during the course of blood-stage malarial infection
Hafalla, Julius C R; Rai, Urvashi; Bernal-Rubio, Dabeiba; Rodriguez, Ana; Zavala, Fidel
2007 Dec 15;196(12):1827-1835, Journal of infectious diseases
Immunity to Plasmodium liver stages in individuals in malaria-endemic areas is inextricably linked to concomitant blood-stage parasitemia. Although Plasmodium sporozoite infection induces measurable CD8+ T cell responses, the development of memory T cells during active erythrocytic infection remains uncharacterized. Using transgenic T cells, we assessed antigen-specific effector CD8+ T cell responses induced by normal (NorSpz) and radiation-attenuated (IrrSpz) Plasmodium yoelii sporozoites. The magnitude, phenotypic activation, and differentiation pathway of CD8+ T cells were similarly induced by NorSpz and IrrSpz. Moreover, in normal mice, memory T cells elicited after priming with NorSpz and IrrSpz generated identical recall responses after a heterologous boost strategy. Furthermore, these recall responses exhibited comparable in vivo antiparasite activity. Our results indicate that sporozoites that retain their infective capacity induce memory CD8+ T cells that are robustly recalled by secondary immunization. Thus, erythrocytic infection does not preclude the establishment of memory CD8+ T cell responses to malarial liver stages
— id: 75702, year: 2007, vol: 196, page: 1827, stat: Journal Article,

Role of TGF-beta and PGE2 in T cell responses during Plasmodium yoelii infection
Ocana-Morgner, Carlos; Wong, Kurt A; Lega, Flavia; Dotor, Javier; Borras-Cuesta, Francisco; Rodriguez, Ana
2007 Jun;37(6):1562-1574, European journal of immunology
During an acute blood-stage malaria infection, T cell responses to malaria and other bystander antigens are inhibited. Plasmodium infection induces strong cytokine responses that facilitate parasite clearance but may interfere with T cell functions, as some of the soluble immune mediators induced are also general inhibitors of T cell responses. Using a malaria mouse model, we have analyzed the cytokines produced by dendritic cells in response to P. yoelii infection that have potential T cell inhibitory activity. We found that during acute infection DC migrate to the spleen and secrete TGF-beta, prostaglandin E2 (PGE2) and IL-10. We have analyzed the role of these general T cell inhibitors in a particular T cell response of evident importance in malaria infections: the CD8+ T cells generated against the liver-stage of the disease. During blood-stage infection, inhibition of the activity of TGF-beta and PGE2 restores the CD8+ T cell responses generated by sporozoites, increasing protection against re-infection. Our findings suggest that the strong cytokine response induced by blood-stage P. yoelii infection affects host T cell responses, inhibiting protective CD8+ T cells against the liver-stage of the disease
— id: 73946, year: 2007, vol: 37, page: 1562, stat: Journal Article,

Plasmodium yoelii yoelii 17XNL constitutively expressing GFP throughout the life cycle
Ono, Takeshi; Tadakuma, Takushi; Rodriguez, Ana
2007 Mar;115(3):310-313, Experimental parasitology
Plasmodium yoelii is a rodent parasite commonly used as a model to study malaria infection. It is the preferred model parasite for liver-stage immunological studies and is also widely used to study hepatocyte, erythrocyte and mosquito infection. We have generated a P. yoelii yoelii 17XNL line that is stably transfected with the green fluorescent protein (gfp) gene. This parasite line constitutively expresses high levels of GFP during the complete parasite life cycle including liver, blood and mosquito stages. These fluorescent parasites can be used in combination with fluorescence activated cell sorting or live microscopy for a wide range of experimental applications
— id: 70089, year: 2007, vol: 115, page: 310, stat: Journal Article,

Molecular characterization of a Plasmodium-derived inflammatory factor
Orengo, JM; Evans, JE; Leliwa-Sytek, A; Day, KP; Rodriguez, A
2007 NOV ;77(5):185-186, American journal of tropical medicine & hygiene
— id: 75812, year: 2007, vol: 77, page: 185, stat: Journal Article,

Developmental arrest of malaria parasites in mosquitoes following treatment of mice with ASI-145
Purcell, LA; Yanow, SK; Pradel, G; Rodriguez, A; Lee, M; Spithill, TW
2007 NOV ;77(5):11-11, American journal of tropical medicine & hygiene
— id: 75807, year: 2007, vol: 77, page: 11, stat: Journal Article,

Potent antimalarial activity of the A/T-specific alkylating agent AS-I-145 against Plasmodium in vitro and in vivo
Yanow, SK; Purcell, LA; Rodriguez, A; Lee, M; Spithill, TW
2007 NOV ;77(5):48-48, American journal of tropical medicine & hygiene
— id: 75811, year: 2007, vol: 77, page: 48, stat: Journal Article,

Priming of CD8+ T cell responses following immunization with heat-killed Plasmodium sporozoites
Hafalla, Julius C R; Rai, Urvashi; Morrot, Alexandre; Bernal-Rubio, Dabeiba; Zavala, Fidel; Rodriguez, Ana
2006 May;36(5):1179-1186, European journal of immunology
Protective immune responses against malaria are induced by immunization with radiation-attenuated Plasmodium sporozoites. In contrast, non-viable, heat-killed sporozoites do not induce protection, emphasizing the requirement for live parasites to achieve effective immune responses. Using an experimental system with CD8+ T cells from T cell receptor-transgenic mice, we analyzed the primary CD8+ T cell responses elicited by heat-killed inactivated sporozoites. We found that the numbers of specific CD8+ T cells induced were much lower compared to when immunizing with attenuated sporozoites; however, the kinetics of activation and the phenotype of these T cells were similar in both groups. Despite their low frequency after priming, high numbers of specific CD8+ T cells were observed after boosting with a recombinant vaccinia virus. Upon induction of the recall response, the same level of protection was observed when either heat-killed or attenuated sporozoites were used for priming. We propose that live parasites are not critical for the induction of memory T cell populations against the malaria liver stages
— id: 64476, year: 2006, vol: 36, page: 1179, stat: Journal Article,

Reply to Renia et al. [2]
Leiriao P; Mota MM; Rodriguez A
2006 ;193(1):164-165, Journal of infectious diseases
— id: 61426, year: 2006, vol: 193, page: 164, stat: Journal Article,

The silent path to thousands of merozoites: the Plasmodium liver stage
Prudencio, Miguel; Rodriguez, Ana; Mota, Maria M
2006 Nov;4(11):849-856, Nature reviews. Microbiology
Plasmodium sporozoites are deposited in the skin of their vertebrate hosts through the bite of an infected female Anopheles mosquito. Most of these parasites find a blood vessel and travel in the peripheral blood circulation until they reach the liver sinusoids. Once there, the sporozoites cross the sinusoidal wall and migrate through several hepatocytes before they infect a final hepatocyte, with the formation of a parasitophorous vacuole, in which the intrahepatic form of the parasite grows and multiplies. During this period, each sporozoite generates thousands of merozoites. As the development of Plasmodium sporozoites inside hepatocytes is an obligatory step before the onset of disease, understanding the parasite's requirements during this period is crucial for the development of any form of early intervention. This Review summarizes our current knowledge on this stage of the Plasmodium life cycle
— id: 78881, year: 2006, vol: 4, page: 849, stat: Journal Article,

HGF/MET signalling protects Plasmodium-infected host cells from apoptosis
Leiriao, Patricia; Albuquerque, Sonia S; Corso, Simona; van Gemert, Geert-Jan; Sauerwein, Robert W; Rodriguez, Ana; Giordano, Silvia; Mota, Maria M
2005 Apr;7(4):603-609, Cellular microbiology
Plasmodium, the causative agent of malaria, migrates through several hepatocytes before initiating a malaria infection. We have previously shown that this process induces the secretion of hepatocyte growth factor (HGF) by traversed cells, which renders neighbour hepatocytes susceptible to infection. The signalling initiated by HGF through its receptor MET has multifunctional effects on various cell types. Our results reveal a major role for apoptosis protection of host cells by HGF/MET signalling on the host susceptibility to infection. Inhibition of HGF/MET signalling induces a specific increase in apoptosis of infected cells leading to a great reduction on infection. Since HGF/MET signalling is capable of protecting cells from apoptosis by using both PI3-kinase/Akt and, to a lesser extent, MAPK pathways, we determined the impact of these pathways on Plasmodium sporozoite infection. Although inhibition of either of these pathways leads to a reduction in infection, inhibition of PI3-kinase/Akt pathway caused a stronger effect, which correlated with a higher level of apoptosis in infected host cells. Altogether, the results show that the HGF/MET signalling requirement for infection is mediated by its anti-apoptotic signal effects. These results demonstrate for the first time that active inhibition of apoptosis in host cell during infection by Plasmodium is required for a successful infection
— id: 78882, year: 2005, vol: 7, page: 603, stat: Journal Article,

Targeting Plasmodium host cells: survival within hepatocytes
Mota, Maria M; Giordano, Silvia; Rodriguez, Ana
2004 Oct;10(10):487-492, Trends in molecular medicine
Upon entering their host, Plasmodium sporozoites travel directly to the liver. Once there, they migrate through several hepatocytes before they infect a final one. During migration, sporozoites breach the plasma membrane of traversed hepatocytes, but to infect they must form a parasitophorous vacuole, in which the intra-hepatic form of the parasite grows and multiplies. During this period there is a remarkable parasite multiplication, but little is known about the requirements and strategies that are developed to be successful. Hepatocyte growth factor and its receptor on hepatocytes might enhance early Plasmodium development within these cells. We anticipate that this might be the basis for further studies on host-cell requirements for Plasmodium development
— id: 78884, year: 2004, vol: 10, page: 487, stat: Journal Article,

Migration through host cells: the first steps of Plasmodium sporozoites in the mammalian host
Mota, Maria M; Rodriguez, Ana
2004 Dec;6(12):1113-1118, Cellular microbiology
Malaria starts with the infection of the liver by Plasmodium sporozoites. This form of the parasite migrates through several host cells breaching their plasma membranes before infecting a final hepatocyte which they enter forming a parasitophorous vacuole. It is still controversial why Plasmodium sporozoites migrate through host cells. By reviewing the most recent literature, we hope to give an insight on the different steps of host invasion in which migration through cells is involved and on the possible role for this mechanism in infection
— id: 78883, year: 2004, vol: 6, page: 1113, stat: Journal Article,

Hepatocyte growth factor and its receptor are required for malaria infection
Carrolo, Margarida; Giordano, Silvia; Cabrita-Santos, Laura; Corso, Simona; Vigario, Ana M; Silva, Susana; Leiriao, Patricia; Carapau, Daniel; Armas-Portela, Rosario; Comoglio, Paolo M; Rodriguez, Ana; Mota, Maria M
2003 Nov;9(11):1363-1369, Nature medicine
Plasmodium, the causative agent of malaria, must first infect hepatocytes to initiate a mammalian infection. Sporozoites migrate through several hepatocytes, by breaching their plasma membranes, before infection is finally established in one of them. Here we show that wounding of hepatocytes by sporozoite migration induces the secretion of hepatocyte growth factor (HGF), which renders hepatocytes susceptible to infection. Infection depends on activation of the HGF receptor, MET, by secreted HGF. The malaria parasite exploits MET not as a primary binding site, but as a mediator of signals that make the host cell susceptible to infection. HGF/MET signaling induces rearrangements of the host-cell actin cytoskeleton that are required for the early development of the parasites within hepatocytes. Our findings identify HGF and MET as potential targets for new approaches to malaria prevention
— id: 78885, year: 2003, vol: 9, page: 1363, stat: Journal Article,

Malaria blood stage suppression of liver stage immunity by dendritic cells
Ocana-Morgner, Carlos; Mota, Maria M; Rodriguez, Ana
2003 Jan 20;197(2):143-151, Journal of experimental medicine
Malaria starts with Plasmodium sporozoites infection of the host's liver, where development into blood stage parasites occurs. It is not clear why natural infections do not induce protection against the initial liver stage and generate low CD8(+) T cell responses. Using a rodent malaria model, we show that Plasmodium blood stage infection suppresses CD8(+) T cell immune responses that were induced against the initial liver stage. Blood stage Plasmodium affects dendritic cell (DC) functions, inhibiting maturation and the capacity to initiate immune responses and inverting the interleukin (IL)-12/IL-10 secretion pattern. The interaction of blood stage parasites with DCs induces the secretion of soluble factors that inhibit the activation of CD8(+) T cells in vitro and the suppression of protective CD8(+) T cell responses against the liver stage in vivo. We propose that blood stage infection induces DCs to suppress CD8(+) T cell responses in natural malaria infections. This evasion mechanism leaves the host unprotected against reinfection by inhibiting the immune response against the initial liver stage of the disease
— id: 33620, year: 2003, vol: 197, page: 143, stat: Journal Article,

Migration through host cells activates Plasmodium sporozoites for infection
Mota, Maria M; Hafalla, Julius C R; Rodriguez, Ana
2002 Nov;8(11):1318-1322, Nature medicine
Plasmodium sporozoites, the infective stage of the malaria parasite transmitted by mosquitoes, migrate through several hepatocytes before infecting a final one. Migration through hepatocytes occurs by breaching their plasma membranes, and final infection takes place with the formation of a vacuole around the sporozoite. Once in the liver, sporozoites have already reached their target cells, making migration through hepatocytes prior to infection seem unnecessary. Here we show that this migration is required for infection of hepatocytes. Migration through host cells, but not passive contact with hepatocytes, induces the exocytosis of sporozoite apical organelles, a prerequisite for infection with formation of a vacuole. Sporozoite activation induced by migration through host cells is an essential step of Plasmodium life cycle
— id: 33622, year: 2002, vol: 8, page: 1318, stat: Journal Article,

Invasion of mammalian host cells by Plasmodium sporozoites
Mota, Maria M; Rodriguez, Ana
2002 Feb;24(2):149-156, Bioessays
Malaria is transmitted through the bite of an infected mosquito, which introduces Plasmodium sporozoites into the mammalian host. Sporozoites rapidly reach the liver of the host where they are sequestered, a process probably mediated by circumsporozoite (CS) protein. Once in the liver, sporozoites migrate through several hepatocytes by breaching their plasma membranes before infecting a final hepatocyte with formation of a vacuole around the sporozoite, where development occurs into blood stage parasites. We propose that migration through several host cells activates sporozoites for ultimate productive invasion. This migration triggers sporozoite exocytosis, which is necessary for hepatocyte invasion, probably because it provides molecules, such as thrombospondin-related anonymous protein (TRAP), likely required for sporozoite invasion with the formation of a vacuole. How sporozoites migrate from the skin to the liver and invade hepatocytes remains unclear. Understanding this initial stage of malaria is crucial for the development of new approaches against the disease
— id: 33623, year: 2002, vol: 24, page: 149, stat: Journal Article,

Dendritic Cells Can Initiate Protective Immune Responses against Malaria
Bruna-Romero O; Rodriguez A
2001 Aug;69(8):5173-5176, Infection & immunity
An understanding of the antigen presentation mechanisms that mediate induction of protective immune responses against malaria is essential for the development of successful immunization approaches. Here we show that dendritic cells presenting Plasmodium yoelii sporozoite antigens are able to activate specific CD4(+) and CD8(+) T cells and initiate protective immune responses against malaria in mice
— id: 21133, year: 2001, vol: 69, page: 5173, stat: Journal Article,

Migration of Plasmodium sporozoites through cells before infection
Mota MM; Pradel G; Vanderberg JP; Hafalla JC; Frevert U; Nussenzweig RS; Nussenzweig V; Rodriguez A
2001 Jan 5;291(5501):141-144, Science
Intracellular bacteria and parasites typically invade host cells through the formation of an internalization vacuole around the invading pathogen. Plasmodium sporozoites, the infective stage of the malaria parasite transmitted by mosquitoes, have an alternative mechanism to enter cells. We observed breaching of the plasma membrane of the host cell followed by rapid repair. This mode of entry did not result in the formation of a vacuole around the sporozoite, and was followed by exit of the parasite from the host cell. Sporozoites traversed the cytosol of several cells before invading a hepatocyte by formation of a parasitophorous vacuole, in which they developed into the next infective stage. Sporozoite migration through several cells in the mammalian host appears to be essential for the completion of the life cycle
— id: 16067, year: 2001, vol: 291, page: 141, stat: Journal Article,

Migration through host cells by apicomplexan parasites
Mota MM; Rodriguez A
2001 Nov;3(13):1123-1128, Microbes & infection
In what appears to be an essential prelude to establish a successful infection in the mammalian host, Plasmodium sporozoites move rapidly through several host cells breaching the cell plasma membranes in the process. This mode of invasion precedes the 'traditional' mode in which the sporozoite enters by invagination of the host cell membrane and develops within a parasitophorous vacuole. Here we revisit the existing literature that supports the presence of similar invasive behaviors in other apicomplexan parasites
— id: 23740, year: 2001, vol: 3, page: 1123, stat: Journal Article,

Plasmodium invasion of mosquito cells: hawk or dove?. Response from Mota and Rodriguez
Mota MM; Rodriguez A
2001 May;17(5):212-212, Trends in parasitology
— id: 20705, year: 2001, vol: 17, page: 212, stat: Journal Article,

Plasmodium yoelii: efficient in vitro invasion and complete development of sporozoites in mouse hepatic cell lines
Mota MM; Rodriguez A
2000 Dec;96(4):257-259, Experimental parasitology
— id: 23741, year: 2000, vol: 96, page: 257, stat: Journal Article,

Fcgamma receptor-mediated induction of dendritic cell maturation and major histocompatibility complex class I-restricted antigen presentation after immune complex internalization
Regnault A; Lankar D; Lacabanne V; Rodriguez A; Thery C; Rescigno M; Saito T; Verbeek S; Bonnerot C; Ricciardi-Castagnoli P; Amigorena S
1999 Jan 18;189(2):371-380, Journal of experimental medicine
Dendritic cells (DCs) express several receptors for the Fc portion of immunoglobulin (Ig)G (FcgammaR), which mediate internalization of antigen-IgG complexes (immune complexes, ICs) and promote efficient major histocompatibility complex (MHC) class II-restricted antigen presentation. We now show that FcgammaRs have two additional specific attributes in murine DCs: the induction of DC maturation and the promotion of efficient MHC class I-restricted presentation of peptides from exogenous, IgG-complexed antigens. Both FcgammaR functions require the FcgammaR-associated gamma chain. FcgammaR-mediated MHC class I-restricted antigen presentation is extremely sensitive and specific to immature DCs. It requires proteasomal degradation and is dependent on functional peptide transporter associated with antigen processing, TAP1-TAP2. By promoting DC maturation and presentation on both MHC class I and II molecules, ICs should efficiently sensitize DCs for priming of both CD4(+) helper and CD8(+) cytotoxic T lymphocytes in vivo
— id: 23743, year: 1999, vol: 189, page: 371, stat: Journal Article,

Selective transport of internalized antigens to the cytosol for MHC class I presentation in dendritic cells
Rodriguez A; Regnault A; Kleijmeer M; Ricciardi-Castagnoli P; Amigorena S
1999 Oct;1(6):362-368, Nature cell biology
In order for cytotoxic T cells to initiate immune responses, peptides derived from internalized antigens must be presented to the cytotoxic T cells on major histocompatibility complex (MHC) class I molecules. Here we show that dendritic cells, the only antigen-presenting cells that initiate immune responses efficiently, have developed a unique membrane transport pathway linking the lumen of endocytic compartments and the cytosol. Endosome-to-cytosol transport is restricted to dendritic cells, specific to internalized antigens and selective for the size of the transported molecules. Thus, in dendritic cells, internalized antigens gain access to the cytosolic antigen-processing machinery and to the conventional MHC class I antigen-presentation pathway
— id: 23742, year: 1999, vol: 1, page: 362, stat: Journal Article,