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Bera S, Amino R, Cockburn IA, Ganusov VV. Heterogeneity in killing efficacy of individual effector CD8 + T cells against Plasmodium liver stages. Proc Biol Sci 2023; 290:20232280. [PMID: 38018100 PMCID: PMC10685130 DOI: 10.1098/rspb.2023.2280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Accepted: 11/01/2023] [Indexed: 11/30/2023] Open
Abstract
Vaccination strategies in mice inducing high numbers of memory CD8+ T cells specific to a single epitope are able to provide sterilizing protection against infection with Plasmodium sporozoites. We have recently found that Plasmodium-specific CD8+ T cells cluster around sporozoite-infected hepatocytes but whether such clusters are important in elimination of the parasite remains incompletely understood. Here, we used our previously generated data in which we employed intravital microscopy to longitudinally image 32 green fluorescent protein (GFP)-expressing Plasmodium yoelii parasites in livers of mice that had received activated Plasmodium-specific CD8+ T cells after sporozoite infection. We found significant heterogeneity in the dynamics of the normalized GFP signal from the parasites (termed 'vitality index' or VI) that was weakly correlated with the number of T cells near the parasite. We also found that a simple model assuming mass-action, additive killing by T cells well describes the VI dynamics for most parasites and predicts a highly variable killing efficacy by individual T cells. Given our estimated median per capita kill rate of k = 0.031/h we predict that a single T cell is typically incapable of killing a parasite within the 48 h lifespan of the liver stage in mice. Stochastic simulations of T cell clustering and killing of the liver stage also suggested that: (i) three or more T cells per infected hepatocyte are required to ensure sterilizing protection; (ii) both variability in killing efficacy of individual T cells and resistance to killing by individual parasites may contribute to the observed variability in VI decline, and (iii) the stable VI of some clustered parasites cannot be explained by measurement noise. Taken together, our analysis for the first time provides estimates of efficiency at which individual CD8+ T cells eliminate intracellular parasitic infection in vivo.
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Affiliation(s)
- Soumen Bera
- Department of Microbiology, University of Tennessee, Knoxville, TN 37996, USA
| | - Rogerio Amino
- Unit of Malaria Infection and Immunity, Institut Pasteur, 75015 Paris, France
| | - Ian A. Cockburn
- Division of Immunology, Inflammation and Infectious Disease, John Curtin School of Medical Research, The Australian National University, Canberra 2600, Australia
| | - Vitaly V. Ganusov
- Department of Microbiology, University of Tennessee, Knoxville, TN 37996, USA
- Department of Mathematics, University of Tennessee, Knoxville, TN 37996, USA
- Host-Pathogen Interactions program, Texas Biomedical Research Institute, San Antonio, TX 78258, USA
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Belhimeur S, Briquet S, Peronet R, Pham J, Commere PH, Formaglio P, Amino R, Scherf A, Silvie O, Mecheri S. Plasmodium-encoded murine IL-6 impairs liver stage infection and elicits long-lasting sterilizing immunity. Front Immunol 2023; 14:1143012. [PMID: 37143657 PMCID: PMC10152192 DOI: 10.3389/fimmu.2023.1143012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 03/27/2023] [Indexed: 05/06/2023] Open
Abstract
Introduction Plasmodium sporozoites (SPZ) inoculated by Anopheles mosquitoes into the skin of the mammalian host migrate to the liver before infecting hepatocytes. Previous work demonstrated that early production of IL-6 in the liver is detrimental for the parasite growth, contributing to the acquisition of a long-lasting immune protection after immunization with live attenuated parasites. Methods Considering that IL-6 as a critical pro-inflammatory signal, we explored a novel approach whereby the parasite itself encodes for the murine IL-6 gene. We generated transgenic P. berghei parasites that express murine IL-6 during liver stage development. Results and Discussion Though IL-6 transgenic SPZ developed into exo-erythrocytic forms in hepatocytes in vitro and in vivo, these parasites were not capable of inducing a blood stage infection in mice. Furthermore, immunization of mice with transgenic IL-6-expressing P. berghei SPZ elicited a long-lasting CD8+ T cell-mediated protective immunity against a subsequent infectious SPZ challenge. Collectively, this study demonstrates that parasite-encoded IL-6 attenuates parasite virulence with abortive liver stage of Plasmodium infection, forming the basis of a novel suicide vaccine strategy to elicit protective antimalarial immunity.
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Affiliation(s)
- Selma Belhimeur
- Institut Pasteur, Université Paris Cité, CNRS ERL9195 and Inserm U1201, Unité de Biologie des Interactions Hôte Parasites, Paris, France
| | - Sylvie Briquet
- Sorbonne Université, Inserm U1135, CNRS ERL 8255, Paris, France
| | - Roger Peronet
- Institut Pasteur, Université Paris Cité, CNRS ERL9195 and Inserm U1201, Unité de Biologie des Interactions Hôte Parasites, Paris, France
| | - Jennifer Pham
- Institut Pasteur, Université Paris Cité, Centre d’élevage et de production des anophèles (CEPIA), Paris, France
| | | | - Pauline Formaglio
- Institut Pasteur, Université Paris Cité, Malaria Infection and Immunity Unit, Paris, France
| | - Rogerio Amino
- Institut Pasteur, Université Paris Cité, Malaria Infection and Immunity Unit, Paris, France
| | - Artur Scherf
- Institut Pasteur, Université Paris Cité, CNRS ERL9195 and Inserm U1201, Unité de Biologie des Interactions Hôte Parasites, Paris, France
| | - Olivier Silvie
- Sorbonne Université, Inserm U1135, CNRS ERL 8255, Paris, France
| | - Salaheddine Mecheri
- Institut Pasteur, Université Paris Cité, CNRS ERL9195 and Inserm U1201, Unité de Biologie des Interactions Hôte Parasites, Paris, France
- *Correspondence: Salaheddine Mecheri,
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Rajakaruna H, Ganusov VV. Mathematical Modeling to Guide Experimental Design: T Cell Clustering as a Case Study. Bull Math Biol 2022; 84:103. [PMID: 35978047 DOI: 10.1007/s11538-022-01063-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 07/28/2022] [Indexed: 11/02/2022]
Abstract
Mathematical modeling provides a rigorous way to quantify immunological processes and discriminate between alternative mechanisms driving specific biological phenomena. It is typical that mathematical models of immunological phenomena are developed by modelers to explain specific sets of experimental data after the data have been collected by experimental collaborators. Whether the available data are sufficient to accurately estimate model parameters or to discriminate between alternative models is not typically investigated. While previously collected data may be sufficient to guide development of alternative models and help estimating model parameters, such data often do not allow to discriminate between alternative models. As a case study, we develop a series of power analyses to determine optimal sample sizes that allow for accurate estimation of model parameters and for discrimination between alternative models describing clustering of CD8 T cells around Plasmodium liver stages. In our typical experiments, mice are infected intravenously with Plasmodium sporozoites that invade hepatocytes (liver cells), and then activated CD8 T cells are transferred into the infected mice. The number of T cells found in the vicinity of individual infected hepatocytes at different times after T cell transfer is counted using intravital microscopy. We previously developed a series of mathematical models aimed to explain highly variable number of T cells per parasite; one of such models, the density-dependent recruitment (DDR) model, fitted the data from preliminary experiments better than the alternative models, such as the density-independent exit (DIE) model. Here, we show that the ability to discriminate between these alternative models depends on the number of parasites imaged in the analysis; analysis of about [Formula: see text] parasites at 2, 4, and 8 h after T cell transfer will allow for over 95% probability to select the correct model. The type of data collected also has an impact; following T cell clustering around individual parasites over time (called as longitudinal (LT) data) allows for a more precise and less biased estimates of the parameters of the DDR model than that generated from a more traditional way of imaging individual parasites in different liver areas/mice (cross-sectional (CS) data). However, LT imaging comes at a cost of a need to keep the mice alive under the microscope for hours which may be ethically unacceptable. We finally show that the number of time points at which the measurements are taken also impacts the precision of estimation of DDR model parameters; in particular, measuring T cell clustering at one time point does not allow accurately estimating all parameters of the DDR model. Using our case study, we propose a general framework on how mathematical modeling can be used to guide experimental designs and power analyses of complex biological processes.
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Rajakaruna H, O'Connor JH, Cockburn IA, Ganusov VV. Liver Environment-Imposed Constraints Diversify Movement Strategies of Liver-Localized CD8 T Cells. J Immunol 2022; 208:1292-1304. [PMID: 35131868 PMCID: PMC9250760 DOI: 10.4049/jimmunol.2100842] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 12/17/2021] [Indexed: 05/11/2023]
Abstract
Pathogen-specific CD8 T cells face the problem of finding rare cells that present their cognate Ag either in the lymph node or in infected tissue. Although quantitative details of T cell movement strategies in some tissues such as lymph nodes or skin have been relatively well characterized, we still lack quantitative understanding of T cell movement in many other important tissues, such as the spleen, lung, liver, and gut. We developed a protocol to generate stable numbers of liver-located CD8 T cells, used intravital microscopy to record movement patterns of CD8 T cells in livers of live mice, and analyzed these and previously published data using well-established statistical and computational methods. We show that, in most of our experiments, Plasmodium-specific liver-localized CD8 T cells perform correlated random walks characterized by transiently superdiffusive displacement with persistence times of 10-15 min that exceed those observed for T cells in lymph nodes. Liver-localized CD8 T cells typically crawl on the luminal side of liver sinusoids (i.e., are in the blood); simulating T cell movement in digital structures derived from the liver sinusoids illustrates that liver structure alone is sufficient to explain the relatively long superdiffusive displacement of T cells. In experiments when CD8 T cells in the liver poorly attach to the sinusoids (e.g., 1 wk after immunization with radiation-attenuated Plasmodium sporozoites), T cells also undergo Lévy flights: large displacements occurring due to cells detaching from the endothelium, floating with the blood flow, and reattaching at another location. Our analysis thus provides quantitative details of movement patterns of liver-localized CD8 T cells and illustrates how structural and physiological details of the tissue may impact T cell movement patterns.
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Affiliation(s)
| | - James H O'Connor
- Division of Immunology, Inflammation and Infectious Disease, John Curtin School of Medical Research, The Australian National University, Canberra, Australia; and
- Australian National University Medical School, Acton, Australian Capital Territory, Australia
| | - Ian A Cockburn
- Division of Immunology, Inflammation and Infectious Disease, John Curtin School of Medical Research, The Australian National University, Canberra, Australia; and
| | - Vitaly V Ganusov
- Department of Microbiology, University of Tennessee, Knoxville, TN;
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Zenkov VS, O’Connor JH, Cockburn IA, Ganusov VV. A New Method Based on the von Mises-Fisher Distribution Shows that a Minority of Liver-Localized CD8 T Cells Display Hard-To-Detect Attraction to Plasmodium-Infected Hepatocytes. Front Bioinform 2022; 1:770448. [PMID: 36303744 PMCID: PMC9580869 DOI: 10.3389/fbinf.2021.770448] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 12/22/2021] [Indexed: 11/13/2022] Open
Abstract
Malaria is a disease caused by Plasmodium parasites, resulting in over 200 million infections and 400,000 deaths every year. A critical step of malaria infection is when sporozoites, injected by mosquitoes, travel to the liver and form liver stages. Malaria vaccine candidates which induce large numbers of malaria-specific CD8 T cells in mice are able to eliminate all liver stages, preventing fulminant malaria. However, how CD8 T cells find all parasites in 48 h of the liver stage lifespan is not well understood. Using intravital microscopy of murine livers, we generated unique data on T cell search for malaria liver stages within a few hours after infection. To detect attraction of T cells to an infection site, we used the von Mises-Fisher distribution in 3D, similar to the 2D von Mises distribution previously used in ecology. Our results suggest that the vast majority (70-95%) of malaria-specific and non-specific liver-localized CD8 T cells did not display attraction towards the infection site, suggesting that the search for malaria liver stages occurs randomly. However, a small fraction (15-20%) displayed weak but detectable attraction towards parasites which already had been surrounded by several T cells. We found that speeds and turning angles correlated with attraction, suggesting that understanding mechanisms that determine the speed of T cell movement in the liver may improve the efficacy of future T cell-based vaccines. Stochastic simulations suggest that a small movement bias towards the parasite dramatically reduces the number of CD8 T cells needed to eliminate all malaria liver stages, but to detect such attraction by individual cells requires data from long imaging experiments which are not currently feasible. Importantly, as far as we know this is the first demonstration of how activated/memory CD8 T cells might search for the pathogen in nonlymphoid tissues a few hours after infection. We have also established a framework for how attraction of individual T cells towards a location in 3D can be rigorously evaluated.
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Affiliation(s)
- Viktor S. Zenkov
- Electrical Engineering and Computer Science, University of Tennessee, Knoxville, TN, United States,*Correspondence: Viktor S. Zenkov, ; Vitaly V. Ganusov,
| | - James H. O’Connor
- Division of Immunology, Inflammation and Infectious Disease, John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia,The Australian National University Medical School, Australian National University, Canberra, ACT, Australia
| | - Ian A. Cockburn
- Division of Immunology, Inflammation and Infectious Disease, John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Vitaly V. Ganusov
- Department of Microbiology, University of Tennessee, Knoxville, TN, United States,Department of Mathematics, University of Tennessee, Knoxville, TN, United States,*Correspondence: Viktor S. Zenkov, ; Vitaly V. Ganusov,
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Djokic V, Rocha SC, Parveen N. Lessons Learned for Pathogenesis, Immunology, and Disease of Erythrocytic Parasites: Plasmodium and Babesia. Front Cell Infect Microbiol 2021; 11:685239. [PMID: 34414129 PMCID: PMC8369351 DOI: 10.3389/fcimb.2021.685239] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 07/15/2021] [Indexed: 11/24/2022] Open
Abstract
Malaria caused by Plasmodium species and transmitted by Anopheles mosquitoes affects large human populations, while Ixodes ticks transmit Babesia species and cause babesiosis. Babesiosis in animals has been known as an economic drain, and human disease has also emerged as a serious healthcare problem in the last 20–30 years. There is limited literature available regarding pathogenesis, immunity, and disease caused by Babesia spp. with their genomes sequenced only in the last decade. Therefore, using previous studies on Plasmodium as the foundation, we have compared similarities and differences in the pathogenesis of Babesia and host immune responses. Sexual life cycles of these two hemoparasites in their respective vectors are quite similar. An adult Anopheles female can take blood meal several times in its life such that it can both acquire and transmit Plasmodia to hosts. Since each tick stage takes blood meal only once, transstadial horizontal transmission from larva to nymph or nymph to adult is essential for the release of Babesia into the host. The initiation of the asexual cycle of these parasites is different because Plasmodium sporozoites need to infect hepatocytes before egressed merozoites can infect erythrocytes, while Babesia sporozoites are known to enter the erythrocytic cycle directly. Plasmodium metabolism, as determined by its two- to threefold larger genome than different Babesia, is more complex. Plasmodium replication occurs in parasitophorous vacuole (PV) within the host cells, and a relatively large number of merozoites are released from each infected RBC after schizogony. The Babesia erythrocytic cycle lacks both PV and schizogony. Cytoadherence that allows the sequestration of Plasmodia, primarily P. falciparum in different organs facilitated by prominent adhesins, has not been documented for Babesia yet. Inflammatory immune responses contribute to the severity of malaria and babesiosis. Antibodies appear to play only a minor role in the resolution of these diseases; however, cellular and innate immunity are critical for the clearance of both pathogens. Inflammatory immune responses affect the severity of both diseases. Macrophages facilitate the resolution of both infections and also offer cross-protection against related protozoa. Although the immunosuppression of adaptive immune responses by these parasites does not seem to affect their own clearance, it significantly exacerbates diseases caused by coinfecting bacteria during coinfections.
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Affiliation(s)
- Vitomir Djokic
- Department for Bacterial Zoonozes, Laboratory for Animal Health, French Agency for Food, Environmental and Occupational Health & Safety, UPEC, University Paris-Est, Maisons-Alfort, France
| | - Sandra C Rocha
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, United States
| | - Nikhat Parveen
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, United States
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Sedegah M, Hollingdale MR, Ganeshan H, Belmonte M, Huang J, Belmonte A, Inoue S, Velasco R, Hickey B, Teneza-Mora N, Lumsden J, Reyes S, Banania JG, Reyes A, Guzman I, Richie TL, Epstein JE, Villasante E. IMRAS-Immunization with radiation-attenuated Plasmodium falciparum sporozoites by mosquito bite: Cellular immunity to sporozoites, CSP, AMA1, TRAP and CelTOS. PLoS One 2021; 16:e0256396. [PMID: 34415964 DOI: 10.1371/journal.pone.0256396] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 07/21/2021] [Indexed: 11/19/2022] Open
Abstract
Background Immunization with radiation-attenuated sporozoites (RAS) by mosquito bites provides >90% sterile protection against Plasmodium falciparum malaria in humans. We conducted a clinical trial based on data from previous RAS clinical trials that suggested that 800–1200 infected bites should induce ~50% protective vaccine efficacy (VE) against controlled human malaria infection (CHMI) administered three weeks after the final immunization. Two cohorts were immunized separately. VE was 55% in Cohort 1 but 90% in Cohort 2, the cohort that received a higher first dose and a reduced (fractional) fifth dose. Immune responses were better boosted by the fractional fifth dose in Cohort 2 and suggested the importance of the fractional fifth dose for increased protection in Cohort 2 responses. Three protected subjects were later boosted and were protected suggesting that protection could be extended to at least 67 weeks. Methods The ex vivo FluoroSpot assay was used to measure peripheral IFN-γ, IL2, and IFN-γ+IL2 responses to PfNF54 sporozoites and malaria antigens CSP, AMA1, TRAP, and CelTOS using pools of synthetic overlapping 15mer peptides spanning each antigen. Results There was no correlation between IFN-γ, IL2, and IFN-γ+IL2 responses to sporozoites and protection, but fold-increases between post-4th and post-5th responses greater than 1.0 occurred mostly in protected subjects. IFN-γ and IL2 responses to TRAP, CelTOS and CSP occurred only in protected subjects. Peripheral IFN-γ, IL2, and IFN-γ+IL2 responses were short-lived and low by 27 weeks post-CHMI but were restored by boosting. Conclusions These studies highlight the importance of vaccine dose and schedule for vaccine efficacy, and suggest that CSP, TRAP, AMA1 and CelTOS may be targets of protective immunity. The correlation between fold-increases in responses and protection should be explored in other vaccine trials. Trial registration ClinicalTrials.gov NCT01994525.
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Sahu T, Gehrke EJ, Flores-Garcia Y, Mlambo G, Romano JD, Coppens I. Chemoprophylaxis vaccination with a Plasmodium liver stage autophagy mutant affords enhanced and long-lasting protection. NPJ Vaccines 2021; 6:98. [PMID: 34376691 PMCID: PMC8355287 DOI: 10.1038/s41541-021-00360-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Accepted: 07/06/2021] [Indexed: 11/09/2022] Open
Abstract
Genetically attenuated sporozoite vaccines can elicit long-lasting protection against malaria but pose risks of breakthrough infection. Chemoprophylaxis vaccination (CVac) has proven to be the most effective vaccine strategy against malaria. Here, we demonstrate that a liver stage-specific autophagy mutant of Plasmodium berghei (ATG8 overexpressor), when used as a live vaccine under a CVac regimen, provides superior long-lasting protection, in both inbred and outbred mice, as compared to WT-CVac. Uniquely, the protection elicited by this mutant is predominantly dependent on a CD8+ T-cell response through an IFN-γ-independent mechanism and is associated with a stable population of antigen-experienced CD8+ T cells. Jointly, our findings support the exploitation of liver-stage mutants as vaccines under a CVac protocol. This vaccination strategy is also a powerful model to study the mechanisms of protective immunity and discover new protective antigens.
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Affiliation(s)
- Tejram Sahu
- Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA.
| | - Ella J Gehrke
- Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
| | - Yevel Flores-Garcia
- Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
| | - Godfree Mlambo
- Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
| | - Julia D Romano
- Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
| | - Isabelle Coppens
- Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA.
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Nguyen VA, Ramanathan M. Application of Brunauer-Emmett-Teller (BET) theory and the Guggenheim-Anderson-de Boer (GAB) equation for concentration-dependent, non-saturable cell-cell interaction dose-responses. J Pharmacokinet Pharmacodyn 2020; 47:561-72. [PMID: 32772303 DOI: 10.1007/s10928-020-09708-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 07/28/2020] [Indexed: 10/23/2022]
Abstract
To systematically assess the characteristics and potential utility of the Guggenheim-Anderson-de Boer (GAB) formulation of the Brunauer-Emmett-Teller (BET) equation from physical chemistry for modeling dose-responses in pharmaceutical applications. The GAB-BET equation was derived using pharmacodynamic first principles to underscore the assumptions involved and the functional characteristics of the equation were investigated. The properties of the GAB-BET equation were compared to the familiar Michaelis-Menten and Hill equations and its utility for pharmacokinetic-pharmacodynamic modeling was assessed by fitting the model equations to four diverse data sets from the literature. The results enabled the salient characteristics of the unconstrained GAB-BET equation and the corresponding GAB-BET equation with finite layers for modeling pharmacodynamic effects to be critically assessed. The GAB-BET approach allows for the accumulation of heterogeneous stacks containing multiple cells or molecules at the target site. The unconstrained GAB-BET equation is capable of describing concentration-dependent dose-response curves that do not exhibit saturation. The GAB-BET equation for finite layers exhibits saturation but increases more slowly than the comparable Michaelis-Menten and Hill equations. The fitting results of the model equations to literature data sets provided support for key aspects of the GAB-BET model. The GAB-BET equation may be a useful method for mechanistic modeling of diverse immune processes and drugs that recruit immune cell activity at the site of action.
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Phares TW, Kotraiah V, Karunarathne DS, Huang J, Browne CD, Buontempo P, Mansour M, Noe AR, Wykes MN, Pannucci J, Tsuji M, Gutierrez GM. A Peptide-Based PD1 Antagonist Enhances T-Cell Priming and Efficacy of a Prophylactic Malaria Vaccine and Promotes Survival in a Lethal Malaria Model. Front Immunol 2020; 11:1377. [PMID: 32733457 PMCID: PMC7363839 DOI: 10.3389/fimmu.2020.01377] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 05/29/2020] [Indexed: 12/14/2022] Open
Abstract
The blockade of programmed cell death-1 (PD1) and its ligand PDL1 has been proven to be a successful immunotherapy against several cancers. Similar to cancer, PD1 contributes to the establishment of several chronic infectious diseases, including malaria. While monoclonal antibodies (mAbs) targeting checkpoint receptors are revolutionary in cancer treatment, the immune-related adverse events (irAEs) may prevent their utilization in prophylactic and therapeutic treatments of infectious diseases. The irAEs are, in part, due to the prolonged half-life of mAbs resulting in prolonged activation of the immune system. As an alternative modality to mAbs, peptides represent a viable option because they possess a shorter pharmacokinetic half-life and offer more formulation and delivery options. Here, we report on a 22-amino acid immunomodulatory peptide, LD01, derived from a Bacillus bacteria. When combined prophylactically with an adenovirus-based or irradiated sporozoite-based malaria vaccine, LD01 significantly enhanced antigen-specific CD8+ T cell expansion. Therapeutically, LD01 treatment of mice infected with a lethal malaria strain resulted in survival that was associated with lower numbers of FOXP3+Tbet+CD4+ regulatory T cells. Taken together, our results demonstrate that LD01 is a potent immunomodulator that acts upon the adaptive immune system to stimulate T cell responses both prophylactically and therapeutically.
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Affiliation(s)
- Timothy W Phares
- Explorations in Global Health (ExGloH), Leidos Inc., Frederick, MD, United States
| | - Vinayaka Kotraiah
- Explorations in Global Health (ExGloH), Leidos Inc., Frederick, MD, United States
| | | | - Jing Huang
- The Aaron Diamond AIDS Research Center, New York, NY, United States
| | | | - Peter Buontempo
- Explorations in Global Health (ExGloH), Leidos Inc., Frederick, MD, United States
| | - Marc Mansour
- Explorations in Global Health (ExGloH), Leidos Inc., Frederick, MD, United States
| | - Amy R Noe
- Leidos Life Sciences, Leidos Inc., Frederick, MD, United States
| | | | - James Pannucci
- Explorations in Global Health (ExGloH), Leidos Inc., Frederick, MD, United States
| | - Moriya Tsuji
- The Aaron Diamond AIDS Research Center, New York, NY, United States
| | - Gabriel M Gutierrez
- Explorations in Global Health (ExGloH), Leidos Inc., Frederick, MD, United States
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