Functional characterization of helminth-associated Clostridiales reveals covariates of Treg differentiation.

BACKGROUND: Parasitic helminths influence the composition of the gut microbiome. However, the microbiomes of individuals living in helminth-endemic regions are understudied. The Orang Asli, an indigenous population in Malaysia with high burdens of the helminth Trichuris trichiura, display microbiotas enriched in Clostridiales, an order of spore-forming obligate anaerobes with immunogenic properties. We previously isolated novel Clostridiales that were enriched in these individuals and found that a subset promoted the Trichuris life cycle. In this study, we aimed to further characterize the functional properties of these bacteria. RESULTS: Clostridiales isolates were profiled for their ability to perform 57 enzymatic reactions and produce short-chain fatty acids (SCFAs) and hydrogen sulfide, revealing that these bacteria were capable of a range of activities associated with metabolism and host response. Consistent with this finding, monocolonization of mice with individual isolates identified bacteria that were potent inducers of regulatory T-cell (Treg) differentiation in the colon. Comparisons between variables revealed by these studies identified enzymatic properties correlated with Treg induction and Trichuris egg hatching. CONCLUSION: We identified Clostridiales species that are sufficient to induce high levels of Tregs. We also identified a set of metabolic activities linked with Treg differentiation and Trichuris egg hatching mediated by these newly isolated bacteria. Altogether, this study provides functional insights into the microbiotas of individuals residing in a helminth-endemic region. Video Abstract.

Myeloid A20 is critical for alternative macrophage polarization and type-2 immune-mediated helminth resistance.

Background: Protective immunity against intestinal helminths requires induction of robust type-2 immunity orchestrated by various cellular and soluble effectors which promote goblet cell hyperplasia, mucus production, epithelial proliferation, and smooth muscle contractions to expel worms and re-establish immune homeostasis. Conversely, defects in type-2 immunity result in ineffective helminth clearance, persistent infection, and inflammation. Macrophages are highly plastic cells that acquire an alternatively activated state during helminth infection, but they were previously shown to be dispensable for resistance to Trichuris muris infection. Methods: We use the in vivo mouse model A20myel-KO, characterized by the deletion of the potent anti-inflammatory factor A20 (TNFAIP3) specifically in the myeloid cells, the excessive type-1 cytokine production, and the development of spontaneous arthritis. We infect A20myel-KO mice with the gastrointestinal helminth Trichuris muris and we analyzed the innate and adaptive responses. We performed RNA sequencing on sorted myeloid cells to investigate the role of A20 on macrophage polarization and type-2 immunity. Moreover, we assess in A20myel-KO mice the pharmacological inhibition of type-1 cytokine pathways on helminth clearance and the infection with Salmonella typhimurium. Results: We show that proper macrophage polarization is essential for helminth clearance, and we identify A20 as an essential myeloid factor for the induction of type-2 immune responses against Trichuris muris. A20myel-KO mice are characterized by persistent Trichuris muris infection and intestinal inflammation. Myeloid A20 deficiency induces strong classical macrophage polarization which impedes anti-helminth type-2 immune activation; however, it promotes detrimental Th1/Th17 responses. Antibody-mediated neutralization of the type-1 cytokines IFN-γ, IL-18, and IL-12 prevents myeloid-orchestrated Th1 polarization and re-establishes type-2-mediated protective immunity against T. muris in A20myel-KO mice. In contrast, the strong Th1-biased immunity in A20myel-KO mice offers protection against Salmonella typhimurium infection. Conclusions: We hereby identify A20 as a critical myeloid factor for correct macrophage polarization and appropriate adaptive mucosal immunity in response to helminth and enteric bacterial infection.

The adaptive immune response to Trichuris in wild versus laboratory mice: An established model system in context.

Laboratory model organisms have provided a window into how the immune system functions. An increasing body of evidence, however, suggests that the immune responses of naive laboratory animals may differ substantially to those of their wild counterparts. Past exposure, environmental challenges and physiological condition may all impact on immune responsiveness. Chronic infections of soil-transmitted helminths, which we define as establishment of adult, fecund worms, impose significant health burdens on humans, livestock and wildlife, with limited treatment success. In laboratory mice, Th1 versus Th2 immune polarisation is the major determinant of helminth infection outcome. Here we compared antigen-specific immune responses to the soil-transmitted whipworm Trichuris muris between controlled laboratory and wild free-ranging populations of house mice (Mus musculus domesticus). Wild mice harbouring chronic, low-level infections produced lower levels of cytokines in response to Trichuris antigen than laboratory-housed C57BL/6 mice. Wild mouse effector/memory CD4+ T cell phenotype reflected the antigen-specific cytokine response across the Th1/Th2 spectrum. Increasing egg shedding was associated with body condition loss. However, local Trichuris-specific Th1/Th2 balance was positively associated with worm burden only in older wild mice. Thus, although the fundamental relationships between the CD4+ T helper cell response and resistance to T. muris infection are similar in both laboratory and wild M. m. domesticus, there are quantitative differences and age-specific effects that are analogous to human immune responses. These context-dependent immune responses demonstrate the fundamental importance of understanding the differences between model and natural systems for translating mechanistic models to 'real world' immune function.

Mucosal Vaccination With Recombinant Tm-WAP49 Protein Induces Protective Humoral and Cellular Immunity Against Experimental Trichuriasis in AKR Mice.

Trichuriasis is one of the most common neglected tropical diseases of the world's poorest people. A recombinant vaccine composed of Tm-WAP49, an immunodominant antigen secreted by adult Trichuris stichocytes into the mucosa of the cecum to which the parasite attaches, is under development. The prototype is being evaluated in a mouse model of Trichuris muris infection, with the ultimate goal of producing a mucosal vaccine through intranasal delivery. Intranasal immunization of mice with Tm-WAP49 formulated with the adjuvant OCH, a truncated analog of alpha-GalCer with adjuvanticity to stimulate natural killer T cells (NKT) and mucosal immunity, induced significantly high levels of IgG and its subclasses (IgG1 and IgG2a) in immunized mice. This also resulted in a significant reduction of worm burden after challenge with T. muris-infective eggs. The addition of QS-21 adjuvant to this vaccine formulation further reduced worm counts. The improved protection from the dual-adjuvanted vaccine correlated with higher serum antibody responses (IgG, IgG1, IgG2a, IgA) as well as with the induction of antigen-specific IgA in the nasal mucosa. It was also associated with the robust cellular responses including functional subsets of CD4 T cells producing IL-4, and cytotoxic CD8 T cells expressing granzyme B. The worm reduction achieved by mucosal immunization was higher than that induced by subcutaneous immunization. Intranasal immunization also induced a significantly higher nasal mucosa-secreted antigen-specific IgA response, as well as higher functional cellular responses including CD4+IL4+ (Th1) and CD8+GnzB+ (Th2) T cells, and antigen-specific INFγ-producing T cells in both spleen and MLNs and antibody-producing B cells (CD19+B220+/B220+GL7+). Mucosal immunization further induced long-term T lymphocyte memory with increased central (CD62L+CD44+) and effector (CD62L-CD44+) memory subsets of both CD4 and CD8 T cells at 60 days after the last immunization. In summary, intranasal immunization with recombinant Tm-WAP49 protein induced strong protection versus murine trichuriasis. It represents a promising vaccination approach against intestinal nematodes.

Parasite worm antigens instruct macrophages to release immunoregulatory extracellular vesicles.

Emerging evidence suggests that immune cells not only communicate with each other through cytokines, chemokines, and cell surface receptors, but also by releasing small membranous structures known as extracellular vesicles (EVs). EVs carry a variety of different molecules that can be taken up by recipient cells. Parasitic worms are well known for their immunomodulatory properties, but whether they can affect immune responses by altering EV-driven communication between host immune cells remains unclear. Here we provide evidence that stimulation of bone marrow-derived macrophages (BMDMs) with soluble products of Trichuris suis (TSPs), leads to the release of EVs with anti-inflammatory properties. Specifically, we found that EVs from TSP-pulsed BMDMs, but not those from unstimulated BMDMs can suppress TNFα and IL-6 release in LPS-stimulated BMDMs and BMDCs. However, no polarization toward M1 or M2 was observed in macrophages exposed to EVs. Moreover, EVs enhanced reactive oxygen species (ROS) production in the exposed BMDMs, which was associated with a deregulated redox homeostasis as revealed by pathway analysis of transcriptomic data. Proteomic analysis identified cytochrome p450 (CYP450) as a potential source of ROS in EVs from TSP-pulsed BMDMs. Finally, pharmacological inhibition of CYP450 activity could suppress ROS production in those BMDMs. In summary, we find that TSPs can modulate immune responses not only via direct interactions but also indirectly by eliciting the release of EVs from BMDMs that exert anti-inflammatory effects on recipient cells.

Trichuris muris infection drives cell-intrinsic IL4R alpha independent colonic RELMα+ macrophages.

The intestinal nematode parasite Trichuris muris dwells in the caecum and proximal colon driving an acute resolving intestinal inflammation dominated by the presence of macrophages. Notably, these macrophages are characterised by their expression of RELMα during the resolution phase of the infection. The RELMα+ macrophage phenotype associates with the presence of alternatively activated macrophages and work in other model systems has demonstrated that the balance of classically and alternatively activated macrophages is critically important in enabling the resolution of inflammation. Moreover, in the context of type 2 immunity, RELMα+ alternatively activated macrophages are associated with the activation of macrophages via the IL4Rα. Despite a breadth of inflammatory pathologies associated with the large intestine, including those that accompany parasitic infection, it is not known how colonic macrophages are activated towards an alternatively activated phenotype. Here, we address this important knowledge gap by using Trichuris muris infection, in combination with transgenic mice (IL4Rαfl/fl.CX3CR1Cre) and IL4Rα-deficient/wild-type mixed bone marrow chimaeras. We make the unexpected finding that education of colonic macrophages towards a RELMα+, alternatively activated macrophage phenotype during T. muris infection does not require IL4Rα expression on macrophages. Further, this independence is maintained even when the mice are treated with an anti-IFNγ antibody during infection to create a strongly polarised Th2 environment. In contrast to RELMα, PD-L2 expression on macrophages post infection was dependent on IL4Rα signalling in the macrophages. These novel data sets are important, revealing a surprising cell-intrinsic IL4R alpha independence of the colonic RELMα+ alternatively activated macrophage during Trichuris muris infection.

Protective Effect of Intestinal Helminthiasis Against Tuberculosis Progression Is Abrogated by Intermittent Food Deprivation.

Background: Tuberculosis (TB) is still a major challenge for humankind. Because regions with the highest incidence also have a high prevalence of helminthiasis and nutritional scarcity, we wanted to understand the impact of these on TB progression. Methods: We have developed an experimental murine model for active TB in C3HeB/FeJ, coinfected with Trichuris muris and Heligmosomoides polygyrus nematodes, and exposed to an environmental mycobacterium (M. manresensis) and intermittent fasting. Cause-effect relationships among these factors were explored with Partial Least Squares Path modelling (PLSPM). Results: Previous parasitization had a major anti-inflammatory effect and reduced systemic levels of ADA, haptoglobin, local pulmonary levels of IL-1ß, IL-6, TNF-α, CXCL-1, CXCL-5 and IL-10. Oral administration of heat-killed M. manresensis resulted in a similar outcome. Both interventions diminished pulmonary pathology and bacillary load, but intermittent food deprivation reduced this protective effect increasing stress and inflammation. The PLSPM revealed nematodes might have protective effects against TB progression. Conclusions: Significantly higher cortisol levels in food-deprivation groups showed it is a stressful condition, which might explain its deleterious effect. This highlights the impact of food security on TB eradication policies and the need to prioritize food supply over deworming activities.

Intestinal-epithelial LSD1 controls goblet cell maturation and effector responses required for gut immunity to bacterial and helminth infection.

Infectious and inflammatory diseases in the intestine remain a serious threat for patients world-wide. Reprogramming of the intestinal epithelium towards a protective effector state is important to manage inflammation and immunity and can be therapeutically targeted. The role of epigenetic regulatory enzymes within these processes is not yet defined. Here, we use a mouse model that has an intestinal-epithelial specific deletion of the histone demethylase Lsd1 (cKO mice), which maintains the epithelium in a fixed reparative state. Challenge of cKO mice with bacteria-induced colitis or a helminth infection model both resulted in increased pathogenesis. Mechanistically, we discovered that LSD1 is important for goblet cell maturation and goblet-cell effector molecules such as RELMß. We propose that this may be in part mediated by directly controlling genes that facilitate cytoskeletal organization, which is important in goblet cell biology. This study therefore identifies intestinal-epithelial epigenetic regulation by LSD1 as a critical element in host protection from infection.

Trichuris trichiura egg extract proteome reveals potential diagnostic targets and immunomodulators.

Embryonated eggs are the infectious developmental stage of Trichuris trichiura and are the primary stimulus for the immune system of the definitive host. The intestinal-dwelling T. trichiura affects an estimated 465 million people worldwide with an estimated global burden of disease of 640 000 DALYs (Disability Adjusted Life Years). In Latin America and the Caribbean, trichuriasis is the most prevalent soil transmitted helminthiasis in the region (12.3%; 95% CI). The adverse health consequences impair childhood school performance and reduce school attendance resulting in lower future wage-earning capacity. The accumulation of the long-term effects translates into poverty promoting sequelae and a cycle of impoverishment. Each infective T. trichiura egg carries the antigens needed to face the immune system with a wide variety of proteins present in the shell, larvae's surface, and the accompanying fluid that contains their excretions/secretions. We used a proteomic approach with tandem mass spectrometry to investigate the proteome of soluble non-embryonated egg extracts of T. trichiura obtained from naturally infected African green monkeys (Chlorocebus sabaeus). A total of 231 proteins were identified, 168 of them with known molecular functions. The proteome revealed common proteins families which are known to play roles in energy and metabolism; the cytoskeleton, muscle and motility; proteolysis; signaling; the stress response and detoxification; transcription and translation; and lipid binding and transport. In addition to the study of the T. trichiura non-embryonated egg proteome, the antigenic profile of the T. trichiura non-embryonated egg and female soluble proteins against serum antibodies from C. sabaeus naturally infected with trichuriasis was investigated. We used an immunoproteomic approach by Western blot and tandem mass spectrometry from the corresponding SDS-PAGE gels. Vitellogenin N and VWD and DUF1943 domain containing protein, poly-cysteine and histidine tailed protein isoform 2, heat shock protein 70, glyceraldehyde-3-phosphate dehydrogenase, actin, and enolase, were among the potential immunoactive proteins. To our knowledge, this is the first study on the T. trichiura non-embryonated egg proteome as a novel source of information on potential targets for immunodiagnostics and immunomodulators from a neglected tropical disease. This initial list of T. trichiura non-embryonated egg proteins (proteome and antigenic profile) can be used in future research on the immunobiology and pathogenesis of human trichuriasis and the treatment of human intestinal immune-related diseases.

The role of ß2 integrin in dendritic cell migration during infection.

BACKGROUND: Dendritic cells (DCs) play a key role in shaping T cell responses. To do this, DCs must be able to migrate to the site of the infection and the lymph nodes to prime T cells and initiate the appropriate immune response. Integrins such as ß2 integrin play a key role in leukocyte adhesion, migration, and cell activation. However, the role of ß2 integrin in DC migration and function in the context of infection-induced inflammation in the gut is not well understood. This study looked at the role of ß2 integrin in DC migration and function during infection with the nematode worm Trichuris muris. Itgb2tm1Bay mice lacking functional ß2 integrin and WT littermate controls were infected with T. muris and the response to infection and kinetics of the DC response was assessed. RESULTS: In infection, the lack of functional ß2 integrin significantly reduced DC migration to the site of infection but not the lymph nodes. The lack of functional ß2 integrin did not negatively impact T cell activation in response to T. muris infection. CONCLUSIONS: This data suggests that ß2 integrins are important in DC recruitment to the infection site potentially impacting the initiation of innate immunity but is dispensible for DC migration to lymph nodes and T cell priming in the context of T. muris infection.

Interleukin-33 Promotes Serotonin Release from Enterochromaffin Cells for Intestinal Homeostasis.

The gastrointestinal tract is known as the largest endocrine organ that encounters and integrates various immune stimulations and neuronal responses due to constant environmental challenges. Enterochromaffin (EC) cells, which function as chemosensors on the gut epithelium, are known to translate environmental cues into serotonin (5-HT) production, contributing to intestinal physiology. However, how immune signals participate in gut sensation and neuroendocrine response remains unclear. Interleukin-33 (IL-33) acts as an alarmin cytokine by alerting the system of potential environmental stresses. We here demonstrate that IL-33 induced instantaneous peristaltic movement and facilitated Trichuris muris expulsion. We found that IL-33 could be sensed by EC cells, inducing release of 5-HT. IL-33-mediated 5-HT release activated enteric neurons, subsequently promoting gut motility. Mechanistically, IL-33 triggered calcium influx via a non-canonical signaling pathway specifically in EC cells to induce 5-HT secretion. Our data establish an immune-neuroendocrine axis in calibrating rapid 5-HT release for intestinal homeostasis.

Soil-Transmitted Helminth Vaccines: Are We Getting Closer?

Parasitic helminths infect over one-fourth of the human population resulting in significant morbidity, and in some cases, death in endemic countries. Despite mass drug administration (MDA) to school-aged children and other control measures, helminth infections are spreading into new areas. Thus, there is a strong rationale for developing anthelminthic vaccines as cost-effective, long-term immunological control strategies, which, unlike MDA, are not haunted by the threat of emerging drug-resistant helminths nor limited by reinfection risk. Advances in vaccinology, immunology, and immunomics include the development of new tools that improve the safety, immunogenicity, and efficacy of vaccines; and some of these tools have been used in the development of helminth vaccines. The development of anthelminthic vaccines is fraught with difficulty. Multiple lifecycle stages exist each presenting stage-specific antigens. Further, helminth parasites are notorious for their ability to dampen down and regulate host immunity. One of the first significant challenges in developing any vaccine is identifying suitable candidate protective antigens. This review explores our current knowledge in lead antigen identification and reports on recent pre-clinical and clinical trials in the context of the soil-transmitted helminths Trichuris, the hookworms and Ascaris. Ultimately, a multivalent anthelminthic vaccine could become an essential tool for achieving the medium-to long-term goal of controlling, or even eliminating helminth infections.

Investigating the importance of B cells and antibodies during Trichuris muris infection using the IgMi mouse.

The IgMi mouse has normal B cell development; its B cells express an IgM B cell receptor but cannot class switch or secrete antibody. Thus, the IgMi mouse offers a model system by which to dissect out antibody-dependent and antibody-independent B cell function. Here, we provide the first detailed characterisation of the IgMi mouse post-Trichuris muris (T. muris) infection, describing expulsion phenotype, cytokine production, gut pathology and changes in T regulatory cells, T follicular helper cells and germinal centre B cells, in addition to RNA sequencing (RNA seq) analyses of wild-type littermates (WT) and mutant B cells prior to and post infection. IgMi mice were susceptible to a high-dose infection, with reduced Th2 cytokines and elevated B cell-derived IL-10 in mesenteric lymph nodes (MLN) compared to controls. A low-dose infection regime revealed IgMi mice to have significantly more apoptotic cells in the gut compared to WT mice, but no change in intestinal inflammation. IL-10 levels were again elevated. Collectively, this study showcases the potential of the IgMi mouse as a tool for understanding B cell biology and suggests that the B cell plays both antibody-dependent and antibody-independent roles post high- and low-dose T. muris infection. KEY MESSAGES: During a high-dose T. muris infection, B cells are important in maintaining the Th1/Th2 balance in the MLN through an antibody-independent mechanism. High levels of IL-10 in the MLN early post-infection, and the presence of IL-10-producing B cells, correlates with susceptibility to T. muris infection. B cells maintain gut homeostasis during chronic T. muris infection via an antibody-dependent mechanism.

Molecular and metabolomic changes in the proximal colon of pigs infected with Trichuris suis.

The pig whipworm Trichuris suis is important in swine production because of its negative effects on pig performance and, notably, to some humans with inflammatory bowel disease as a therapeutic agent that modulates inflammation. The proximal colon of T. suis-infected pigs exhibited general inflammation around day 21 after inoculation with infective eggs that is transcriptionally characterized by markers of type-2 immune activation, inflammation, cellular infiltration, tissue repair enzymes, pathways of oxidative stress, and altered intestinal barrier function. Prominent gene pathways involved the Th2-response, de novo cholesterol synthesis, fructose and glucose metabolism, basic amino acid metabolism, and bile acid transport. Upstream regulatory factor analysis implicated the bile acid/farnesoid X receptor in some of these processes. Metabolic analysis indicated changes in fatty acids, antioxidant capacity, biochemicals related to methylation, protein glycosylation, extracellular matrix structure, sugars, Krebs cycle intermediates, microbe-derived metabolites and altered metabolite transport. Close to 1,200 differentially expressed genes were modulated in the proximal colon of pigs with a persistent adult worm infection that was nearly 90% lower in pigs that had expelled worms. The results support a model to test diets that favorably alter the microbiome and improve host intestinal health in both pigs and humans exposed to Trichuris.

Interactions between helminths and tuberculosis infections: Implications for tuberculosis diagnosis and vaccination in Africa.

Africa is the second most populous continent and has perennial health challenges. Of the estimated 181 million school aged children in sub-Saharan Africa (SSA), nearly half suffer from ascariasis, trichuriasis, or a combination of these infections. Coupled with these is the problem of tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) infection, which is a leading cause of death in the region. Compared to the effect of the human immunodeficiency virus on the development of TB, the effect of chronic helminth infections is a neglected area of research, yet helminth infections are as ubiquitous as they are varied and may potentially have profound effects upon host immunity, particularly as it relates to TB infection, diagnosis, and vaccination. Protection against active TB is known to require a clearly delineated T-helper type 1 (Th1) response, while helminths induce a strong opposing Th2 and immune-regulatory host response. This Review highlights the potential challenges of helminth-TB co-infection in Africa and the need for further research.

Fermentable Dietary Fiber Promotes Helminth Infection and Exacerbates Host Inflammatory Responses.

Fermentable dietary fibers promote the growth of beneficial bacteria, can enhance mucosal barrier integrity, and reduce chronic inflammation. However, effects on intestinal type 2 immune function remain unclear. In this study, we used the murine whipworm Trichuris muris to investigate the effect of the fermentable fiber inulin on host responses to infection regimes that promote distinct Th1 and Th2 responses in C57BL/6 mice. In uninfected mice, dietary inulin stimulated the growth of beneficial bacteria, such as Bifidobacterium (Actinobacteria) and Akkermansia (Verrucomicrobia). Despite this, inulin prevented worm expulsion in normally resistant mice, instead resulting in chronic infection, whereas mice fed an equivalent amount of nonfermentable fiber (cellulose) expelled worms normally. Lack of expulsion in the mice fed inulin was accompanied by a significantly Th1-skewed immune profile characterized by increased T-bet+ T cells and IFN-γ production in mesenteric lymph nodes, increased expression of Ido1 in the cecum, and a complete absence of mast cell and IgE production. Furthermore, the combination of dietary inulin and high-dose T. muris infection caused marked dysbiosis, with expansion of the Firmicutes and Proteobacteria phyla, near elimination of Bacteroidetes, and marked reductions in cecal short-chain fatty acids. Neutralization of IFN-γ during infection abrogated Ido1 expression and was sufficient to restore IgE production and worm expulsion in inulin-fed mice. Our results indicate that, whereas inulin promoted gut health in otherwise healthy mice, during T. muris infection, it exacerbated inflammatory responses and dysbiosis. Thus, the positive effects of fermentable fiber on gut inflammation appear to be context dependent, revealing a novel interaction between diet and infection.

In silico design of a T-cell epitope vaccine candidate for parasitic helminth infection.

Trichuris trichiura is a parasite that infects 500 million people worldwide, leading to colitis, growth retardation and Trichuris dysentery syndrome. There are no licensed vaccines available to prevent Trichuris infection and current treatments are of limited efficacy. Trichuris infections are linked to poverty, reducing children's educational performance and the economic productivity of adults. We employed a systematic, multi-stage process to identify a candidate vaccine against trichuriasis based on the incorporation of selected T-cell epitopes into virus-like particles. We conducted a systematic review to identify the most appropriate in silico prediction tools to predict histocompatibility complex class II (MHC-II) molecule T-cell epitopes. These tools were used to identify candidate MHC-II epitopes from predicted ORFs in the Trichuris genome, selected using inclusion and exclusion criteria. Selected epitopes were incorporated into Hepatitis B core antigen virus-like particles (VLPs). Bone marrow-derived dendritic cells and bone marrow-derived macrophages responded in vitro to VLPs irrespective of whether the VLP also included T-cell epitopes. The VLPs were internalized and co-localized in the antigen presenting cell lysosomes. Upon challenge infection, mice vaccinated with the VLPs+T-cell epitopes showed a significantly reduced worm burden, and mounted Trichuris-specific IgM and IgG2c antibody responses. The protection of mice by VLPs+T-cell epitopes was characterised by the production of mesenteric lymph node (MLN)-derived Th2 cytokines and goblet cell hyperplasia. Collectively our data establishes that a combination of in silico genome-based CD4+ T-cell epitope prediction, combined with VLP delivery, offers a promising pipeline for the development of an effective, safe and affordable helminth vaccine.

Accelerated onset of CNS prion disease in mice co-infected with a gastrointestinal helminth pathogen during the preclinical phase.

Prion infections in the central nervous system (CNS) can cause extensive neurodegeneration. Systemic inflammation can affect the progression of some neurodegenerative disorders. Therefore, we used the gastrointestinal helminth pathogen Trichuris muris to test the hypothesis that a chronic systemic inflammatory response to a gastrointestinal infection would similarly affect CNS prion disease pathogenesis. Mice were injected with prions directly into the CNS and subsequently orally co-infected with T. muris before the onset of clinical signs. We show that co-infection with a low dose of T. muris that leads to the development of a chronic T helper cell type 1-polarized systemic immune response accelerated the onset of clinical prion disease. In contrast, co-infection with a high dose of T. muris that induces a T helper cell type 2-polarized immune response did not affect prion disease pathogenesis. The reduced survival times in mice co-infected with a low dose of T. muris on d 105 after CNS prion infection coincided with enhanced astrocyte activation in the brain during the preclinical phase. These data aid our understanding of how systemic inflammation may augment the progression of neurodegeneration in the CNS.

Noninvasive measurement of mucosal immunity in a free-ranging baboon population.

Ecoimmunological patterns and processes remain understudied in wild primates, in part because of the lack of noninvasive methods to measure immunity. Secretory immunoglobulin A (sIgA) is the most abundant antibody present at mammalian mucosal surfaces and provides an important first line of defense against pathogens. Recent studies show that sIgA can be measured noninvasively in feces and is a good marker of mucosal immunity. Here we validated a commercial ELISA kit to measure fecal IgA in baboons, tested the robustness of its results to variation in collection and storage conditions, and developed a cost-effective in-house ELISA for baboon fecal IgA. Using data from the custom ELISA, we assessed the relationship between fecal IgA concentrations and gastrointestinal parasite burden, and tested how sex, age, and reproductive effort predict fecal IgA in wild baboons. We find that IgA concentrations can be measured in baboon feces using an in-house ELISA and are highly correlated to the values obtained with a commercial kit. Fecal IgA concentrations are stable when extracts are stored for up to 22 months at -20°C. Fecal IgA concentrations were negatively correlated with parasite egg counts (Trichuris trichiura), but not parasite richness. Fecal IgA did not vary between the sexes, but for males, concentrations were higher in adults versus adolescents. Lactating females had significantly lower fecal IgA than pregnant females, but neither pregnant nor lactating female concentrations differed significantly from cycling females. Males who engaged in more mate-guarding exhibited similar IgA concentrations to those who engaged in little mate-guarding. These patterns may reflect the low energetic costs of mucosal immunity, or the complex dependence of IgA excretion on individual condition. Adding a noninvasive measure of mucosal immunity will promote a better understanding of how ecology modulates possible tradeoffs between the immune system and other energetically costly processes in the wild.

Cytokine production in allergic and Trichuris trichiura-infected children from an urban region of the Brazilian northeast.

The relationship between the cellular immune response during Trichuris trichiura infection and asthma has not yet been established. In this study, the cytokines interleukin (IL)-2, IL-4, IL-6, IL-10, TNF-α, IFN-γ and IL-17A were evaluated in asthmatic children harboring T. trichiura. For this assessment, asthmatic and non-asthmatic children (ISAAC questionnaire) were submitted to parasitological tests and blood samples were cultured (mitogen stimulation) for cytokine measurements in the supernatant. Asthma frequencies were similar in infected and uninfected children, but IL-4, IL-6, TNF-α and IL-10 levels were high in the infected asthmatic children. Additionally, infected non-asthmatic children exhibited high levels of these cytokines in relation to uninfected non-asthmatic children; however, cytokine levels were lower when compared with infected and asthmatic children. Therefore, T. trichiura infection positively modulated the pro- and anti-inflammatory cytokines in asthmatic children, but a background of asthma seemed to narrow the production of cytokines induced by this helminth.