Constraint-based network model of pathogen-immune system interactions.
ABSTRACT: Pathogenic bacteria such as Bordetella bronchiseptica modulate host immune responses to enable their establishment and persistence; however, the immune response is generally successful in clearing these bacteria. Here, we model the dynamic outcome of the interplay between host immune components and B. bronchiseptica virulence factors. The model extends our previously published interaction network of B. bronchiseptica and includes the existing experimental information on the relative timing of IL10 and IFNgamma activation in the form of qualitative inequalities. The current model improves the previous one in two directions: (i) by augmenting the network with new nodes with specific function in T helper cell differentiation and effector mechanisms and (ii) by using a dynamic approach that allows us to quantify node states and mechanisms revealed to be important from our previous model. The model makes predictions about the time scales of each process, the activity thresholds of each node and novel regulatory interactions. For example, the model predicts that the activity threshold of IL4 is higher than that of IL12 and that pro-inflammatory cytokines regulate the activity of Th2 cells. Some of these predictions are supported by the literature, and many can serve as targets of future experiments.
Project description:Interferons are key modulators of the immune system, and are central to the control of many diseases. The response of immune cells to stimuli in complex populations is the product of direct and indirect effects, and of homotypic and heterotypic cell interactions. Dissecting the global transcriptional profiles of immune cell populations may provide insights into this regulatory interplay. The host transcriptional response may also be useful in discriminating between disease states, and in understanding pathophysiology. The transcriptional programs of cell populations in health therefore provide a paradigm for deconvoluting disease-associated gene expression profiles.We used human cDNA microarrays to (1) compare the gene expression programs in human peripheral blood mononuclear cells (PBMCs) elicited by 6 major mediators of the immune response: interferons alpha, beta, omega and gamma, IL12 and TNFalpha; and (2) characterize the transcriptional responses of purified immune cell populations (CD4+ and CD8+ T cells, B cells, NK cells and monocytes) to IFNgamma stimulation. We defined a highly stereotyped response to type I interferons, while responses to IFNgamma and IL12 were largely restricted to a subset of type I interferon-inducible genes. TNFalpha stimulation resulted in a distinct pattern of gene expression. Cell type-specific transcriptional programs were identified, highlighting the pronounced response of monocytes to IFNgamma, and emergent properties associated with IFN-mediated activation of mixed cell populations. This information provides a detailed view of cellular activation by immune mediators, and contributes an interpretive framework for the definition of host immune responses in a variety of disease settings.
Project description:BACKGROUND: CARD15/NOD2 mutations are associated with susceptibility to Crohn's Disease (CD) and Graft Versus Host Disease (GVHD). CD and GVHD are suspected to be related with the dysfunction of Peyer's patches (PP) and isolated lymphoid follicles (LFs). Using a new mouse model invalidated for Card15/Nod2 (KO), we thus analysed the impact of the gene in these lymphoid formations together with the development of experimental colitis. METHODOLOGY/PRINCIPAL FINDINGS: At weeks 4, 12 and 52, the numbers of PPs and LFs were higher in KO mice while no difference was observed at birth. At weeks 4 and 12, the size and cellular composition of PPs were analysed by flow cytometry and immunohistochemistry. PPs of KO mice were larger with an increased proportion of M cells and CD4(+) T-cells. KO mice were also characterised by higher concentrations of TNFalpha, IFNgamma, IL12 and IL4 measured by ELISA. In contrast, little differences were found in the PP-free ileum and the spleen of KO mice. By using chamber experiments, we found that this PP phenotype is associated with an increased of both paracellular permeability and yeast/bacterial translocation. Finally, KO mice were more susceptible to the colitis induced by TNBS. CONCLUSIONS: Card15/Nod2 deficiency induces an abnormal development and function of the PPs characterised by an exaggerated immune response and an increased permeability. These observations provide a comprehensive link between the molecular defect and the Human CARD15/NOD2 associated disorders: CD and GVHD.
Project description:The spatiotemporal distribution of cytokines orchestrates immune responses in vivo, yet the underlying mechanisms remain to be explored. We showed here that the spatial distribution of interleukin-4 (IL4) in invariant natural killer T (iNKT) cells regulated crosstalk between iNKT cells and dendritic cells (DCs) and controlled iNKT cell-mediated T-helper type 1 (Th1) responses. The persistent polarization of IL4 induced by strong lipid antigens, that is, ?-galactosylceramide (?GC), caused IL4 accumulation at the immunological synapse (IS), which promoted the activation of the IL4R-STAT6 (signal transducer and activator of transcription 6) pathway and production of IL12 in DCs, which enhanced interferon-? (IFN?) production in iNKT cells. Conversely, the nonpolarized secretion of IL4 induced by Th2 lipid antigens with a short or unsaturated chain was incapable of enhancing this iNKT cell-DC crosstalk and thus shifted the immune response to a Th2-type response. The nonpolarized secretion of IL4 in response to Th2 lipid antigens was caused by the degradation of Cdc42 in iNKT cells. Moreover, reduced Cdc42 expression was observed in tumor-infiltrating iNKT cells, which impaired IL4 polarization and disturbed iNKT cell-DC crosstalk in tumors.
Project description:Dendritic cells (DC) are the professional antigen presenting cells (APC) that bridge the innate and adaptive immune system. Previously, in a CD11c/EYFP transgenic mouse developed to study DC functions, we anatomically mapped and phenotypically characterized a discrete population of EYFP(+) cells within the microglia that we termed brain dendritic cells (bDC). In this study, we advanced our knowledge of the function of these cells in the CD11c/EYFP transgenic mouse and its chimeras, using acute stimuli of stereotaxically inoculated IFNgamma or IL-4 into the CNS. The administration of IFNgamma increased the number of EYFP(+)bDC but did not recruit peripheral DC into the CNS. IFNgamma, but not IL-4, upregulated the expression levels of major histocompatibility class II (MHC-II). In addition, IFNgamma-activated EYFP(+)bDC induced antigen-specific naïve CD4 T cells to proliferate and secrete Th1/Th17 cytokines. Activated bDC were also able to stimulate naïve CD8 T cells. Collectively, these data reveal the Th1 cytokine IFNgamma, but not the Th2 cytokine IL4, induces bDC to up-regulate MHC-II and become competent APC.
Project description:Data implicating mucosal cytokines in the pathogenesis of canine inflammatory bowel disease (IBD) are limited. The aims of the present study were to report new findings of intestinal cytokine expression in dogs with IBD and to compare these data with previous studies through meta-analysis. Cytokine mRNA abundance in intestinal biopsies collected prospectively was evaluated by using a semiquantitative RT-PCR technique. For meta-analysis, an electronic database search revealed 3 clinical trials, all of which were nonrandomized (type III) case series. Prospective analysis showed that the intestines of healthy dogs and those with IBD express numerous cytokines and that a proinflammatory expression profile is not a feature of small or large-intestinal IBD. The meta-analysis data included 158 dogs characterized as healthy (n = 45), diarrheic nonIBD dogs (n = 6), nonresponders (n = 2), small-intestinal IBD (n = 41), colonic IBD (n = 25), and chronic enteropathy (n = 39). German shepherd dogs were overrepresented in 3 of the 4 studies. Healthy dogs showed mRNA expression for most cytokines including IL2, IL4, IL5, IL10, IL12, IFNgamma, TNFalpha, and TGFbeta. Only IL12 mRNA expression was increased consistently in small-intestinal IBD, whereas IBD colitis lacked consistent patterns of expression. In summary, dogs with IBD fail to express a predominant Th1- or Th2 cytokine bias in inflamed mucosa. Heterogeneity of results among these studies might be explained by numerous factors including the method of mRNA quantification, stage of disease, and demographic differences in study populations.
Project description:Recent studies have demonstrated that Bacillus subtilis-derived poly-gamma glutamic acid (?PGA) treatment suppresses the development of allergic diseases such as atopic dermatitis (AD). Although basophils, an innate immune cell, are known to play critical roles in allergic immune responses and repeated long-term administration of ?PGA results in decreased splenic basophils in an AD murine model, the underlying mechanisms by which ?PGA regulates basophil frequency remain unclear. To investigate how ?PGA modulates basophils, we employed basophil-mediated Th2 induction in vivo model elicited by the allergen papain protease. Repeated injection of ?PGA reduced the abundance of basophils and their production of IL4 in mice, consistent with our previous study using NC/Nga AD model mice. The depletion of basophils by a single injection of ?PGA was dependent on the TLR4/DC/IL12 axis. CD1d-dependent V?14 TCR invariant natural killer T (iNKT) cells are known to regulate a variety of immune responses, such as allergy. Because iNKT cell activation is highly sensitive to IL12 produced by DCs, we evaluated whether the effect of ?PGA on basophils is mediated by iNKT cell activation. We found that in vivo ?PGA treatment did not induce the reduction of basophils in iNKT cell-deficient CD1d KO mice, suggesting the critical role of iNKT cells in ?PGA-mediated basophil depletion at the early time points. Furthermore, increased apoptotic basophil reduction triggered by iNKT cells upon ?PGA stimulation was mainly attributed to Th1 cytokines such as IFN? and TNF?, consequently resulting in inhibition of papain-induced Th2 differentiation via diminishing basophil-derived IL4. Taken together, our results clearly demonstrate that ?PGA-induced iNKT cell polarization toward the Th1 phenotype induces apoptotic basophil depletion, leading to the suppression of Th2 immune responses. Thus, elucidation of the crosstalk between innate immune cells will contribute to the design and development of new therapeutics for Th2-mediated immune diseases such as AD.
Project description:BACKGROUND: HBB, IL4, IL12, TNF, LTA, NCR3 and FCGR2A polymorphisms have been associated with malaria resistance in humans, whereas cytophilic immunoglobulin G (IgG) antibodies are thought to play a critical role in immune protection against asexual blood stages of the parasite. Furthermore, HBB, IL4, TNF, and FCGR2A have been associated with both malaria resistance and IgG levels. This suggests that some malaria resistance genes influence the levels of IgG subclass antibodies. METHODS: In this study, the effect of HBB, IL4, IL12, TNF, LTA, NCR3 and FCGR2A polymorphisms on the levels of IgG responses against Plasmodium falciparum blood-stage extract was investigated in 220 individuals living in Burkina Faso. The Pearson's correlation coefficient among IgG subclasses was determined. A family-based approach was used to assess the association of polymorphisms with anti-P. falciparum IgG, IgG1, IgG2, IgG3 and IgG4 levels. RESULTS: After applying a multiple test correction, several polymorphisms were associated with IgG subclass or IgG levels. There was an association of i) haemoglobin C with IgG levels; ii) the Fc?RIIa H/R131 with IgG2 and IgG3 levels; iii) TNF-863 with IgG3 levels; iv) TNF-857 with IgG levels; and, v) TNF1304 with IgG3, IgG4, and IgG levels. CONCLUSION: Taken together, the results support the hypothesis that some polymorphisms affect malaria resistance through their effect on the acquired immune response, and pave the way towards further comprehension of genetic control of an individual's humoral response against malaria.
Project description:Efficacious antitumor vaccines strongly stimulate cancer-specific effector T cells and counteract the activity of tumor-infiltrating immunosuppressive cells. We hypothesised that combining cytokine expression with silencing programmed cell death ligand 1 (PD-L1) could potentiate anticancer immune responses of lentivector vaccines. Thus, we engineered a collection of lentivectors that simultaneously co-expressed an antigen, a PD-L1-silencing shRNA, and various T cell-polarising cytokines, including interferon ? (IFN?), transforming growth factor ? (TGF?) or interleukins (IL12, IL15, IL23, IL17A, IL6, IL10, IL4). In a syngeneic B16F0 melanoma model and using tyrosinase related protein 1 (TRP1) as a vaccine antigen, we found that simultaneous delivery of IL12 and a PD-L1-silencing shRNA was the only combination that exhibited therapeutically relevant anti-melanoma activities. Mechanistically, we found that delivery of the PD-L1 silencing construct boosted T cell numbers, inhibited <i>in vivo</i> tumor growth and strongly cooperated with IL12 cytokine priming and antitumor activities. Finally, we tested the capacities of our vaccines to counteract tumor-infiltrating myeloid-derived suppressor cell (MDSC) activities <i>ex vivo</i>. Interestingly, the lentivector co-expressing IL12 and the PD-L1 silencing shRNA was the only one that counteracted MDSC suppressive activities, potentially underlying the observed anti-melanoma therapeutic benefit. We conclude that (1) evaluation of vaccines in healthy mice has no significant predictive value for the selection of anticancer treatments; (2) B16 cells expressing xenoantigens as a tumor model are of limited value; and (3) vaccines which inhibit the suppressive effect of MDSC on T cells in our <i>ex vivo</i> assay show promising and relevant antitumor activities.
Project description:BACKGROUND & OBJECTIVES: Tuberculosis is (TB) responsible for high morbidity and mortality worldwide. Cytokines play a major role in defense against Mycobacterium tuberculosis infection. Polymorphisms in the genes encoding the various pro- and anti-inflammatory cytokines have been associated with tuberculosis susceptibility. In this study we examined association of 25 sequence polymorphisms in six candidate cytokine genes namely IFNG, TNFB, IL4, IL1RA, IL1B and IL12 and their related haplotypes with risk of developing pulmonary tuberculosis (PTB) among north Indians. METHODS: Pulmonary TB (n=110) patients and 215 healthy controls (HC) from north India were genotyped. Purified multiplex PCR products were subjected to mass spectrometry using Sequenom MassARRAY platform to generate the genotypes in a population-based case-control study. RESULTS: Using multiple corrections, significant overall risk against PTB was observed at seven loci which included variants in IFNG at rs1861493 and rs1861494; IL1RA at rs4252019, IL4 variant rs2070874, IL12 variants rs3212220, rs2853694 and TNFB variant rs1041981. Analysis of gene structure revealed two haplotype blocks formed by IFNG variants rs1861493 and rs1861494. The TA haplotype was significantly over-represented (P=0.011) in the cases showing a two-fold risk in the current population (Odds ratio=1.59 CI=1.101 to 2.297) and TNFB variants at rs2229094 and rs1041981 contributed to two haplotypes which were in strong linkage disequilibrium (LD) with AT haplotype showing a three-fold risk (P=0.0011, Odds ratio=3, CI=0.1939 to 0.7445) of developing PTB in north Indians. INTERPRETATION & CONCLUSIONS: Our study showed six novel associations of cytokine gene variants with susceptibility to PTB in north Indians. Variants of IFNG and TNFB emerged as factors imposing a significant risk of developing PTB in north Indians apart from risk indicated by IL1RA, IL4 and IL12.
Project description:<h4>Background</h4>Interleukin (IL)-12 is a pro-inflammatory cytokine that mediates T-helper type 1 responses and cytotoxic T-cell activation, contributing to its utility as anti-cancer agent. Systemic administration of IL-12 often results in unacceptable toxicity; therefore, strategies to direct delivery of IL-12 to tumors are under investigation. The objective of this study was to assist the preclinical development of NHS-IL12, an immunocytokine consisting of an antibody, which targets necrotic tumor regions, linked to IL-12. Specifically this study sought to evaluate the safety, serum pharmacokinetics, anti-tumor activity, and immune modulation of NHS-IL12 in dogs with naturally occurring cancers.<h4>Methodology/principal findings</h4>A rapid dose-escalation study of NHS-IL12 administered subcutaneously to dogs with melanoma was conducted through the Comparative Oncology Trials Consortium (COTC). Eleven dogs were enrolled in four dose-escalation cohorts; thereafter, an additional seven dogs were treated at the defined tolerable dose of 0.8 mg/m2. The expanded cohort at this fixed dose (ten dogs in total) was accrued for further pharmacokinetics and pharmacodynamics assessment. NHS-IL12 levels, serum cytokine concentrations, and peripheral blood mononuclear cell characterization (post-treatment) and draining lymph node immune profiling, and tumor biopsies (pre- and post-treatment) were collected. Adverse events included thrombocytopenia, liver enzymopathies, fever, and vasculitis. Correlation between interferon (IFN)-? induction, adverse events, and NHS-IL12 exposure (maximum concentration and area under the concentration-time curve) were dose-dependent. Serum IL-10 levels and intratumoral CD8+ populations increased after treatment. Partial responses, according to Response Evaluation Criteria in Solid Tumors (RECIST) criteria, were observed in two dogs treated with NHS-IL12 0.8 mg/m2 and 1.6 mg/m2.<h4>Conclusions/significance</h4>NHS-IL12 was administered safely to dogs with melanoma and both immunologic and clinical activity was observed. This study successfully defined a narrow therapeutic window for systemic delivery of NHS-IL12 via the subcutaneous route. Results will inform the design and implementation of first-in-human clinical trials of NHS-IL12 in cancer patients.