Expression of interleukin-9 leads to Th2 cytokine-dominated responses and fatal enteropathy in mice with chronic Schistosoma mansoni infections

The abundance and morphology of human large intestinal goblet and tuft cells during chronic schistosomiasis

Schistosomiasis affects nearly 240 million people in predominately low- and middle-income countries and ranks second in the number of cases and socio-economic burden among all parasitic diseases. Despite the enormous burden posed by schistosomes, our understanding of how schistosomiasis impacts infected human tissues remains limited. Intestinal schistosomiasis in animal models leads to goblet cell hyperplasia, likely increasing mucus production and reflecting an intestinal type 2 immune response. However, it is unknown whether these same changes occur in schistosome-infected humans. Using immunofluorescence and light microscopy, we compared the abundance and morphology of goblet cells in patients diagnosed with schistosomiasis to uninfected controls. The mucin-containing vesicles in goblet cells from schistosome-infected patients were significantly larger (hypertrophic) than uninfected individuals, although goblet cell hyperplasia was absent in chronic human schistosomiasis. In addition, we examined tuft cells in the large intestinal epithelium of control and schistosome-infected patients. Tuft cell numbers expand during helminth infection in mice, but these cells have not been characterized in human parasite infections. We found no evidence of tuft cell hyperplasia during human schistosome infection. Thus, our study provides novel insight into schistosome-associated changes to the intestinal epithelium in humans, suggesting an increase in mucus production by large intestinal goblet cells but relatively minor effects on tuft cell numbers.

Characteristics of Th9 cells in Schistosoma japonicum-infected C57BL/6 mouse mesenteric lymph node

Interleukin 9 (IL-9) is an effective cytokine secreted by newly defined Th9 cells, which is involved in allergic and infectious diseases. In this study, lymphocytes were isolated from mesenteric lymph node (MLN), spleen, liver, lung, and Peyer's patches (PP) of C57BL/6 mice 5-6 weeks after S. japonicum infection, intracellular cytokine staining was done to detect the percentage of IL-9-producing CD4⁺ T cells. The qPCR and ELISA were used to verify the content of IL-9 in MLN. The population of IL-9-producing lymphocyte subset was identified by FACS. In addition, the dynamic changes and cytokine profiles of Th9 cells in the MLN of infected mice were detected by FACS. ELISA was used to detect IL-9 induced by soluble egg antigen (SEA) from isolated lymphocytes in mouse MLN. The results showed that the percentage of IL-9-secreting Th9 cells in the MLN of the infected mouse was higher than that in the spleen, liver, lung, or PP. Though CD8⁺ Tc cells, NKT cells, and γδT cells could secrete IL-9, CD4⁺ Th cells were the main source of IL-9 in S. japonicum-infected C57BL/6 mice (P < 0.05). The percentage of Th9 cells in MLN of infected mouse increased from week 3-4, and reached a peak at week 5-6, then began to decrease from week 7-8 (P < 0.05). Moreover, Th9 cells could also secrete a small amount of IL-4, IFN-γ, IL-5, and IL-10. Our results suggested a higher percentage of Th9 cells was induced in the MLN of S. japonicum-infected mice, which might play an important role in the early stage of S. japonicum-induced disease.

Immunopathology and modulation induced by hookworms: From understanding to intervention

Hookworm infection is considered the most prevalent human soil-transmitted helminth infection affecting approximately 500 million people and accounting for 3.2 million disability-adjusted life years lost annually. As with many other neglected tropical diseases, no international surveillance mechanisms that show accurate data on the prevalence of hookworm infection are in place, thus hindering strategies to control parasite transmission. In this review, we unravel the current knowledge in immunopathology and immunoregulation of hookworm infection and present discoveries in drug therapies based on the capability of hookworms to regulate inflammation to treat allergic, inflammatory and metabolic diseases. Additionally, we highlight potential vaccine development and treatments and propose avenues for further inquiry.

Granuloma formation and tissue pathology in Schistosoma japonicum versus Schistosoma mansoni infections

Schistosomiasis is the most important helminth disease in the world from a public health perspective. S mansoni and S japonicum account for the majority of global intestinal schistosomiasis cases, and the pathogenesis is widely assumed to be fundamentally similar. However, the majority of research on schistosomiasis has been carried out on S mansoni and comparisons between the two species are rarely made. Here, we will discuss aspects of both older and recent literature where such comparisons have been made, with a particular focus on the pathological agent, the host granulomatous response to the egg. Major differences between the two species are apparent in features such as egg production patterns and cellular infiltration; however, it is also clear that even subtle differences in the cascade of various cytokines and chemokines contribute to the different levels of pathology observed between these two main species of intestinal schistosomiasis. A better understanding of such differences at species level will be vital when it comes to the development of new treatment strategies and vaccines.

Immunomodulatory dynamics of excretory and secretory products on Th9 immune response during Haemonchus contortus infection in goat

CD4+ T cells play critical roles in mediating adaptive immunity to a variety of pathogens. Recently, new subset of CD4+T named as T helper 9 cells that express the prototypical interleukin-9 (IL-9) cytokine have been recognized in human and mice models during different parasitic infections. Haemonchus contortus is a gastrointestinal nematode of small ruminants which cause high mortality in young animals. During infection, Excretory and Secretary Products (ESPs) are released in the host body. No other study has reported yet on immunomodulatory dynamics of H. contortus ESPs on Th9 immune response in vitro or in vivo. In this study, immunomodulatory effects of ESPs (5, 10, 20, 40, 80; μg/mL) incubated with goat PBMCs on Th9 cells, IL-9 immune response and TGF-β/Smad signaling regulator were evaluated in vitro. Moreover, for in vivo study, goats were infected with different doses (P-800, P-2400, and P-8000) of H. contortus infective larva (L3) and immunomodulatory effects on Th9 cells, IL-9 immune response and TGF-β/Smad signaling regulator were evaluated at 7, 10, 14, 18, 21, 28 Days Post Infection (DPI). Flow cytometry was performed to evaluate the effects on Th9 cells and quantitative real time polymerase chain reaction was performed to evaluate the IL-9 cytokine transcription level. Additionally, fecal egg counting was also performed in parallel to confirm the infection. All goats were dewormed at 29 DPI and all experiments were also performed at 35 DPI, one week post deworming. The finding indicated that 10, 20, 40, 80 μg/mL concentration of ESPs incubated with goat PBMCs showed significant increase in the production of Th9 cells, signature cytokine IL-9 and expression of TGF-β/Smad signaling regulator as compared to control group in vitro.All infected groups showed significant increase in production of Th9 cells and IL-9 cytokine and expression of TGF-β/Smad key genes at 18, 21, and 28 DPI as compared to control group. Likewise, at 14 DPI, P-2400 and P-8000 groups showed significant increase in production of Th9 cells, IL-9 cytokine and expression of TGF-β/Smad key genes. While at 10 DPI, production of Th9 cells and IL-9 was significantly increased in P-2400 & P-8000 groups, and at 7 DPI only P-8000 showed significantly increase in IL-9 production. No immunomodulatory effects were observed at 0 and 3 DPI. Additionally, significant gradually up-regulated key genes expression of TGF-β/Smad signaling regulator in all infected groups confirmed the above results. After deworming, production of Th9 cells, associated immune response and expression of signaling regulator in each group were significantly decreased. Based on this study, it is concluded that Th9 immune response was induced during H. contortus infection in goat by up-regulation of TGF-β/Smad signaling key genes.

Haemonchus contortus is one of the most pathogenic nematodes of small ruminants in tropical and sub-tropical areas of the world. This parasite is responsible for anemia, edema, and death in young animal which can lead to billions of economic losses globally. Excretory and secretory products (ESPs) are produced by the parasite to modulate the immune response and to protect both parasite and the host. Th9 cells are a subset of CD4+ T cells producing IL-9 cytokine. Th9 cells were increasingly recognized for being important in immunity to intestinal infection with helminths. In this study, immunomodulatory effects of ESPs on PBMCs derived Th9 cells, IL-9 cytokine and TGF-β/Smad signalling were evaluated in vitro and in vivo. Furthermore, Th9 cells production was significantly enhanced on 7, 10, 14, 18, 21, and 28 Days Post Infection (DPI), while no effect was observed at 0 and 3 DPI in vivo. Moreover, the production of IL-9 and TGF-β/Smad Pathway key genes increased gradually from 7 to 28 DPI in vivo. After deworming, production of Th9 cells was gradually decreased in each group.

Galectin Domain Containing Protein from Haemonchus contortus Modulates the Immune Functions of Goat PBMCs and Regulates CD4+ T-Helper Cells In Vitro

Galectins are glycan-binding proteins that are widely expressed and distributed in mammalian tissues as well as cells of innate and adaptive immune responses. CD4+ T-helper cells differentiate into effector subsets in response to cytokines. T helper 9 cells are one of the recently described subsets of effector T cells that are relatively new and less studied. In this study, galectin domain containing protein from Haemonchus contortus (Hc-GDC) was cloned, expressed in pET32a, and immunoblotting was performed. Localization of recombinant (r)Hc-GDC on outer and inner surface of H. contortus worm and binding with goat Peripheral Blood Mononuclear cells (PBMCs) were performed using immunofluorescence assay. Moreover, effects of rHc-GDC on proliferation, apoptosis, cell migration, and the nitric oxide production in goat PBMCs were evaluated. Furthermore, modulatory effects of rHc-GDC on production of Th1, Th2, and Th9 cells were evaluated by flowcytometry and on interferon gamma, interleukin (IL)-4 and IL-9 were evaluated by quantitative real-time polymerase chain reaction. The results demonstrated that rHc-GDC was successfully cloned, expressed in expression vector as well as in the gut surface of adult H. contortus worm and successful binding with PBMCs surface were observed. Immunoblotting results revealed that rHc-GDC is an important active protein of H. contortus excretory and secretory products. Moreover, the interaction of rHc-GDC with host cells increased the production of Th2, Th9 cells, IL4, IL-9, PBMC proliferation, nitric oxide, and cell migration. No effects of rHc-GDC were observed on PMBC apoptosis, production of Th1 cells, and secretions of IFN- and IL-10 cytokines. These findings indicate that recombinant GDC protein from H. contortus modulates the immune functions of goat PBMCs and has the potential to enhance protective immunity by inducing T helper-9-derived IL-9 in vitro.

Characteristics of IL-9 induced by Schistosoma japonicum infection in C57BL/6 mouse liver

Liver granulomatous inflammation and fibrosis were the primary pathological changes observed during Schistosoma japonicum (S. japonicum) infection. In the present study, the characteristics of IL-9 were investigated in the liver of S. japonicum infection C57BL/6 mice. Immunofluorescence, qRT-PCR, and ELISA results demonstrated that the expression of IL-9 significantly increased after infection (P < 0.01). FACS results indicated that the peak of IL-9⁺ Th9 cells in the liver mononuclear cells appeared at the early phase of infection (week 5), except that Th9 cells, CD8⁺ Tc cells, NKT and γδT cells could secrete IL-9 in this model. Although IL-9 neutralization has a limited effect on liver granulomatous inflammation, it could decrease the level of fibrosis-associated factor, PC-III, in the serum of infected mice (P < 0.05). Taken together, our results indicated that IL-9 was an important type of cytokine involved in the progression of S. japonicum infection-induced hepatic damage.

Interleukin-9 Promotes Pancreatic Cancer Cells Proliferation and Migration via the miR-200a/Beta-Catenin Axis

Background. Both IL-9 and miR-200a are involved in the pathogenesis of cancers; however, the role of IL-9 in pancreatic cancer and the possible underlying mechanisms remain unknown. The aim of this study was to investigate the effect of IL-9 on pancreatic cancer cells and its interaction with miR-200a. Methods. Pancreatic cancer cells (PANC-1 and AsPC-1) were treated with IL-9 and the expression of miR-200a and β-catenin in pancreatic cancer cells was measured. β-Catenin was examined as a target gene of miR-200a in pancreatic cancer cells. The interaction between IL-9 and miR-200a in pancreatic cancer cells was determined by infecting miR-200a mimics prior to IL-9 treatment and then measuring miR-200a and β-catenin expression. Results. IL-9 significantly promoted the proliferation, invasion, and migration of pancreatic cancer cells; however, the effect on pancreatic cancer cell apoptosis was insignificant. β-Catenin was verified as a target gene of miR-200a in pancreatic cancer cells. Overexpression of miR-200a in pancreatic cancer cells significantly attenuated proliferation and metastasis and reduced β-catenin expression. IL-9 treatment of pancreatic cancer cells decreased miR-200a expression and increased β-catenin expression. The effect of miR-200a on pancreatic cancer cells decreased following IL-9 treatment. Conclusions. IL-9 promotes proliferation and metastasis in pancreatic cancer cells; this effect may partly involve regulation of the miR-200a/β-catenin axis.

T Cell Receptor and Co-Stimulatory Signals for Th9 Generation

In vitro polarization of naïve CD4⁺ T cells toward distinct T helper lineages is crucial for establishing the factors and features that determine the differentiation, stability, and effector function for each T helper subsets. In this regard, the recently defined Th9 subset has been reported with two essential cytokines requirement for their generation. Generating Th9 cells in vitro from naïve CD4⁺ T cells requires the combination of TGF-β and IL-4. However, the amount of IL-9 producing under these minimal conditions is often small. The intent of this chapter is to provide examples to increase the generation of IL-9 producing T cells in vitro by modulating TCR strength and co-stimulation through the TNF family member TL1A. We hope that these methods to efficiently differentiate naïve CD4⁺ T cells toward IL-9 producing cells will facilitate understanding the differentiation and function of Th9 cells and their pathogenesis in various inflammatory and autoimmune diseases.

Th9 Cells and Parasitic Inflammation: Use of Nippostrongylus and Schistosoma Models

Th9 cells are a new subpopulation of CD4+ T helper cells, characterized by the expression of IL-9 that have been involved in type 2 immune responses, antitumor responses and autoimmune diseases. Here, we describe two different parasitic models frequently maintained in the laboratory where Th9 cells or IL-9 (the cytokine produced by Th9 cells) has been shown to play critical roles in pathogen clearance and immune response activation: the nematode Nippostrongylus brasiliensis and the trematode Schistosoma mansoni.

Evaluation of serum levels of IL-9 and IL-17 in human Schistosoma mansoni infection and their relationship with periportal fibrosis

Serum levels of IL-9 and IL-17 cytokines were evaluated in patients in the acute, chronic phases and clinical forms of human schistosomiasis and in different classifications of periportal fibrosis. No significant differences between the groups of the disease with serum levels of cytokine were found. However, this study discusses the results of some cytokines that have not fully defined roles in the pathology of human schistosomiasis. Furthermore, an examination was made of subjects in the acute phase. This is an important group that is difficult to identify in areas where the disease is endemic. More studies are being undertaken to study the role of IL-9 and IL-17 in human Schistosoma mansoni infection and their relationship with the immunopathogenesis of disease.

Immune polarization by hookworms: taking cues from T helper type 2, type 2 innate lymphoid cells and alternatively activated macrophages

Cellular and molecular investigation of parasitic helminth infections has greatly accelerated the understanding of type 2 immune responses. However, there remains considerable debate regarding the specific leucocytes that kill parasites and whether these mechanisms are distinct from those responsible for tissue repair. Herein, we chronicle discoveries over the past decade highlighting current paradigms in type 2 immunity with a particular emphasis upon how CD4(+) T helper type 2 cells, type 2 innate lymphoid cells and alternatively activated macrophages coordinately control helminth-induced parasitism. Primarily, this review will draw from studies of the murine nematode parasite Nippostrongylus brasiliensis, which bears important similarities to the human hookworms Ancylostoma duodenale and Necator americanus. Given that one or more hookworm species currently infect millions of individuals across the globe, we propose that vaccine and/or pharmaceutical-based cure strategies targeting these affected human populations should incorporate the conceptual advances outlined herein.

Itk is required for Th9 differentiation via TCR-mediated induction of IL-2 and IRF4

Th9 cells produce interleukin (IL)-9, a cytokine implicated in allergic asthma and autoimmunity. Here we show that Itk, a mediator of T cell receptor signalling required for Th2 immune responses and the development of asthma, is a positive regulator of Th9 differentiation. In a model of allergic lung disease, Itk-deficient mice show reduced pulmonary inflammation and IL-9 production by T cells and innate lymphoid type 2 cells (ILC2), despite normal early induction of ILC2s. In vitro, Itk(-/-) CD4(+) T cells do not produce IL-9 and have reduced levels of IRF4 (Interferon Regulator Factor 4), a critical transcription factor for effector T cell function. Both IL-9 and IRF4 expression are rescued by either IL-2 or constitutively active STAT5, but not NFATc1. STAT5 binds the Irf4 promoter, demonstrating one mechanism by which IL-2 rescues weakly activated T cells. Itk inhibition also reduces IL-9 expression by human T cells, implicating ITK as a key regulator of Th9 induction.

T helper 9 cells induced by plasmacytoid dendritic cells regulate interleukin-17 in multiple sclerosis

We have established a novel role in multiple sclerosis for a molecule, called IL-9, produced by immune cells. IL-9 reduces inflammation, and its expression in the cerebrospinal fluid of patients inversely correlates with the severity of multiple sclerosis.

Th9 Cells Drive Host Immunity against Gastrointestinal Worm Infection

Type 2 inflammatory cytokines, including interleukin-4 (IL-4), IL-5, IL-9, and IL-13, drive the characteristic features of immunity against parasitic worms and allergens. Whether IL-9 serves an essential role in the initiation of host-protective responses is controversial, and the importance of IL-9- versus IL-4-producing CD4⁺ effector T cells in type 2 immunity is incompletely defined. Herein, we generated IL-9-deficient and IL-9-fluorescent reporter mice that demonstrated an essential role for this cytokine in the early type 2 immunity against Nippostrongylus brasiliensis. Whereas T helper 9 (Th9) cells and type 2 innate lymphoid cells (ILC2s) were major sources of infection-induced IL-9 production, the adoptive transfer of Th9 cells, but not Th2 cells, caused rapid worm expulsion, marked basophilia, and increased mast cell numbers in Rag2-deficient hosts. Taken together, our data show a critical and nonredundant role for Th9 cells and IL-9 in host-protective type 2 immunity against parasitic worm infection.

IL-9-mediated survival of type 2 innate lymphoid cells promotes damage control in helminth-induced lung inflammation

IL-9 acts as an autocrine amplifier of type 2 innate lymphoid cell function to promote tissue repair in the recovery phase of helminth-induced lung infection.

IL-9 fate reporter mice established type 2 innate lymphoid cells (ILC2s) as major producers of this cytokine in vivo. Here we focus on the role of IL-9 and ILC2s during the lung stage of infection with Nippostrongylus brasiliensis, which results in substantial tissue damage. IL-9 receptor (IL-9R)–deficient mice displayed reduced numbers of ILC2s in the lung after infection, resulting in impaired IL-5, IL-13, and amphiregulin levels, despite undiminished numbers of Th2 cells. As a consequence, the restoration of tissue integrity and lung function was strongly impaired in the absence of IL-9 signaling. ILC2s, in contrast to Th2 cells, expressed high levels of the IL-9R, and IL-9 signaling was crucial for the survival of activated ILC2s in vitro. Furthermore, ILC2s in the lungs of infected mice required the IL-9R to up-regulate the antiapoptotic protein BCL-3 in vivo. This highlights a unique role for IL-9 as an autocrine amplifier of ILC2 function, promoting tissue repair in the recovery phase after helminth-induced lung inflammation.

From interleukin-9 to T helper 9 cells

Interleukin-9 (IL-9), cloned more than 20 years ago, was initially thought to be a Th2-specific cytokine. This assumption was initially confirmed by functional analyses showing that both IL-9 and Th2 cells play an important role in the pathogenesis of asthma, IgE class switch recombination, and resolution of parasitic infections. However, recently it was shown that IL-9-producing CD4(+) T cells represent the discrete T helper subset Th9 cells. Herein, we will review the cytokines and transcription factors known to promote the development of Th9 cells and their potential functional properties in relation to the biological activities of IL-9. In addition, we will discuss how Th9 cells are related to Th2, Th17, and T(reg) cells, as both an alternative source of IL-9 and in view of the fact that plasticity of CD4(+) T cell differentiation is currently a strong matter of debate in immunologic research.

Schistosoma mansoni antigen Sm-p80: Prophylactic efficacy of a vaccine formulated in human approved plasmid vector and adjuvant (VR 1020 and alum)

Schistosomiasis is an important parasitic disease. Consensus is developing now that ideal control methods of the disease should be based on an integrated approach incorporating drug treatment, sanitation improvement, education, and an effective vaccine. With regards to the vaccine development, Sm-p80 has been shown to be a promising and strong immunogenic vaccine candidate. In the present study, Sm-p80-based vaccine formulated in alum was tested for its prophylactic efficacy in a mouse model. It was observed that vaccination using heterologous prime boost (DNA prime followed by boost with protein formulated in alum) and homologous prime boost (both prime and boost with protein formulated in alum) approaches, resulted in 61% and 55% reduction in worm burden, respectively. The protection was directly correlated with the induction of high titers of antibody responses that mainly included IgG, its isotypes, and IgM. In addition, both of the immunization approaches triggered a mixed Th1 and Th2 type response. Some involvement of Th17 specific immune response was also detected as indicated by the up-regulation of relevant cytokines. These results reinforce the potential of Sm-p80 as a viable vaccine candidate.

Pathway analysis comparison using Crohn's disease genome wide association studies

Background

The use of biological annotation such as genes and pathways in the analysis of gene expression data has aided the identification of genes for follow-up studies and suggested functional information to uncharacterized genes. Several studies have applied similar methods to genome wide association studies and identified a number of disease related pathways. However, many questions remain on how to best approach this problem, such as whether there is a need to obtain a score to summarize association evidence at the gene level, and whether a pathway, dominated by just a few highly significant genes, is of interest.

Methods

We evaluated the performance of two pathway-based methods (Random Set, and Binomial approximation to the hypergeometric test) based on their applications to three data sets of Crohn's disease. We consider both the disease status as a phenotype as well as the residuals after conditioning on IL23R, a known Crohn's related gene, as a phenotype.

Results

Our results show that Random Set method has the most power to identify disease related pathways. We confirm previously reported disease related pathways and provide evidence for IL-2 Receptor Beta Chain in T cell Activation and IL-9 signaling as Crohn's disease associated pathways.

Conclusions

Our results highlight the need to apply powerful gene score methods prior to pathway enrichment tests, and that controlling for genes that attain genome wide significance enable further biological insight.

Th9 and allergic disease

Helper CD4(+) T-cell subsets have improved our understanding of adaptive immunity in humans and in animal models of disease. These include T helper type 1 (Th1), Th2 and the interleukin-17 (IL-17) -producing population 'Th17'. Th2 cells have been described as orchestrating the immune response in allergic disease based on studies with patient samples and animal models. The cytokine IL-9 has largely been regarded as a Th2 cytokine that makes multifocal contributions to allergic disease. Recent data suggest that under certain conditions relevant to chronic disease (IL-4 and transforming growth factor-beta), a distinct population of IL-9-producing 'Th9' helper T cells can exist. The contribution of Th9 cells in allergic disease is currently unknown, and this review will propose a model for how these cells may regulate chronic allergic inflammation.

Recombinant interleukin-4 enhances Campylobacter jejuni invasion of intestinal pig epithelial cells (IPEC-1)

Campylobacter jejuni, a leading cause of bacterial gastroenteritis, has a diverse spectrum of disease expression. Polymicrobial infections may contribute to this, such as Trichuris, which elicits type 2 cytokines (including IL-4) and downregulates type 1 immunity. In previous studies, gnotobiotic piglets infected with C. jejuni and Trichuris suis had bloody diarrhea and marked gastrointestinal pathology, including bacterial invasion into epithelial cells and macrophages. Neonatal swine given these dual infections had elevated IL-4 and IL-10 responses in feces. In the studies reported here, we hypothesized that IL-4 or IL-10 enhances invasion of intestinal pig epithelial cells (IPEC-1) by C. jejuni. 10-14-day-old IPEC-1 cells were pretreated with recombinant IL-4 (rIL-4) or rIL-10 for 5h and then challenged with C. jejuni. Cells pretreated with rIL-4 were viable and showed approximately 6-fold increases in C. jejuni (but not Escherichia coli DH5alpha) internalization compared to cells with no pretreatment. Enhanced C. jejuni invasion was rIL-4 dose-dependent and reversed by addition of anti-IL-4 antibody. Preincubation with rIL-10 did not significantly alter C. jejuni internalization. Transepithelial electrical resistance (TEER) was significantly reduced following rIL-4 treatment, but not rIL-10 treatment. After rIL-4 pretreatment and C. jejuni challenge, light microscopy showed vacuolated cells with damaged paracellular junctions. Transmission electron microscopy (TEM) showed multiple internalized bacteria. Most were in the cytoplasm, but some were within or adjacent to vacuoles. We conclude that rIL-4 damages paracellular junctions and alters the physiology of these epithelial cells allowing increased invasion of C. jejuni.

The immunological effects of electrolyzed reduced water on the Echinostoma hortense infection in C57BL/6 mice

Electrolyzed reduced water (ERW) is widely used for drinking by people in Asia. The purpose of this study was to examine the immunological effect of ERW on the immunity of animals by supplying ERW to C57BL/6 mice infected with Echinostoma hortense metacercariae. In the non-infected groups, interleukin (IL)-4 (p < 0.001), IL-5, IL-10, IL-1beta, tumor necrosis factor (TNF)-alpha and immunoglobulin (Ig) A expression of the group fed ERW (ERW group) increased in small intestine compared with the normal control group. In the case of infected groups, the group fed ERW (ERW+E. hortense group) showed the result that IL-4, IL-5, IL-10 and Ig A expression increased, but IL-1beta and TNF-alpha (p < 0.001) decreased, and the number of goblet cells (p < 0.001) and helix pomatia agglutinin (HPA) positive cells increased compared with the group without feeding ERW. However, adult worm recovery rate was markedly increased (p < 0.05). On the other hand, the expression of all the cytokines except IL-10 in spleen was mildly increased but not significant statistically, and there was no significant difference in the numerical changes of white blood cell (WBC). These results indicate that feeding ERW may have influence on the local immune response (Th-1 type cytokines such as IL-1beta, TNF-alpha) in the small intestine but not on the systemic immune response.

IL-4/IL-13 independent goblet cell hyperplasia in experimental helminth infections

BACKGROUND

Intestinal mucus production by hyperplasic goblet cells is a striking pathological feature of many parasitic helminth infections and is related to intestinal protection and worm expulsion. Induction of goblet cell hyperplasia is associated with TH2 immune responses, which in helminth infections are controlled primarily by IL-13, and also IL-4. In the study presented here we examine the goblet cell hyperplasic response to three experimental parasitic helminth infections; namely Nippostrongylus brasiliensis, Syphacia obvelata and Schistosoma mansoni.

RESULTS

As expected N. brasiliensis infection induced a strong goblet cell hyperplasia dependent on IL-4/IL-13/IL-4Ralpha expression. In contrast, and despite previously published transiently elevated IL-4/IL-13 levels, S. obvelata infections did not increase goblet cell hyperplasia in the colon. Furthermore, induction of goblet cell hyperplasia in response to S. mansoni eggs traversing the intestine was equivalent between BALB/c, IL-4/IL-13-/- and IL-4Ralpha-/- mice.

CONCLUSION

Together these data demonstrate that intestinal goblet cell hyperplasia can be independent of TH2 immune responses associated with parasitic helminth infections.

Role for CTLA-4 but not CD25+T cells during Schistosoma mansoni infection of mice

Schistosoma mansoni infection of mice increases the frequency of cells that are CD4+ CD25+ in the acute (4 and 8 weeks) and chronic (16 week) stages of infection. Depletion of > 85% of CD25+ cells in the acute or chronic stages of schistosome infection caused no overt changes in morbidity or immunological responses. The absence of effect in mice with CD25+ cells depleted may be due to the preferential expression of IL-4 and IL-10, two cytokines that are protective in schistosome infection, on CD25- CD4+ cells. We also assessed infection-induced changes of other regulatory markers, GITR, CD103 and CTLA-4 on CD4+ cells. We identified a marked expansion of CTLA-4+ population on CD25- CD4+ cells in acute and chronic infection. Blocking of CTLA-4 during acute, but not chronic infection, caused significant weight loss and altered the type 2 cytokine response of mice, with increased IL-4 and IL-5 production associated with significantly more Th2 cells and eosinophils in the liver granuloma. This study illustrates the complexity of regulation of T cells in schistosome infection and highlights a specific role for CTLA-4+, but not CD25+ cells, in the regulation of Th2 responses in helminth infection.

IL-9 promotes anti-Mycobacterium leprae cytotoxicity: involvement of IFNgamma

Interleukin 9 (IL-9) is a T-cell derived factor preferentially expressed by CD4+ Th2 cells and it has been characterized both in human and murine systems. It is a pleiotropic cytokine with multiple functions on cells of the lymphoid, myeloid and mast cell lineages, as well as on lung epithelial cells. Other activities described for IL-9 support its contribution to asthma and its important role in helminthic infections, where a Th2 response can be protective and IL-9 enhances resistance or is responsible for elimination of the nematode. Nevertheless, until recently there were no studies on its role in bacterial infections in man. We have demonstrated that cytokines can modulate the specific cytotoxicity generation in peripheral blood mononuclear cells from leprosy patients and normal controls. In the present report we studied the effect of IL-9 in this experimental model. Our results indicate that IL-9 can counteract the negative effect mediated by IL-4 on the generation of M. leprae-induced cytotoxic T lymphocytes. Moreover, it can increase this lytic activity in controls and enhance the stimulatory effect of IL-2 or IL-6 in cells from leprosy patients and controls. IL-9 is also able to revert the inhibitory effect of IL-10 and IL-13 on the M. leprae-induced cytotoxic activity. Although the exact mechanism of action of IL-9 remains to be determined, interferon gamma seems to be required for the effect of IL-9 in this experimental model. These data suggest that IL-9 may have an atypical Th2 behaviour and play a role in the modulation of the immune response to mycobacterial infections.

A case of bowel schistosomiasis not adhering to endoscopic findings

Schistosomiasis is a chronic worm infection caused by a species of trematodes, the Schistosomes. We may distinguish a urinary form from Schistosomes haematobium and an intestinal-hepatosplenic form mainly from Schistosomes mansoni characterized by nausea, meteorism, abdominal pain, bloody diarrhea, rectal tenesmus, and hepatosplenomegaly. These infections represent a major health issue in Africa, Asia, and South America, but recently S mansoni has increased its prevalence in other continents, such as Europe countries and North America, due to international travelers and immigrants, with several diagnostic and prevention problems. We report a case of a 24-year-old patient without HIV infection, originated from Ghana, admitted for an afebrile dysenteric syndrome. All microbiologic studies were negative and colonoscopy revealed macroscopic lesions suggestive of a bowel inflammatory chronic disease. Since symptoms became worse, a therapy with mesalazine (2 g/d) was started, depending on the results of a bowel biopsy, but without any resolution. The therapy was stopped after 2 wk when the following result was available: a diagnosis of ""intestinal schistosomiasis" was done (two Schistosoma eggs were detected in the colonic mucosa) and this was confirmed by the detection of Schistosoma eggs in the feces. Therapy was therefore changed to praziquantel (40 mg/kg, single dose), a specific anti-parasitic agent, with complete recovery. Schistosomiasis shows some peculiar difficulties in terms of differential diagnosis from the bowel inflammatory chronic disease, as the two disorders may show similar colonoscopic patterns. Since this infection has recently increased its prevalence worldwide, it has to be considered in the differential diagnosis of our patients with gastrointestinal symptoms.

Immunopathogenesis of schistosomiasis

In schistosomiasis mansoni, the chronic egg-induced granulomatous response in the liver and intestines may eventually cause extensive tissue scarring and development of portal hypertension. Indeed, much of the morbidity and mortality associated with this disease is directly attributable to the deposition of connective tissue elements in affected tissues. Elucidating the mechanisms that regulate the severity of schistosomiasis has been a major research objective over the past several years. Research conducted with DNA microarrays as well as investigations with a variety of gene knock-out mice have been particularly helpful in achieving this goal. A notable accomplishment in the past few years was the identification of interleukin-13 (IL-13) and the IL-13 receptor complex as central regulators of disease progression in schistosomiasis. Liver fibrogenesis is severely decreased in infected IL-13-deficient mice as well as in wildtype animals treated with IL-13 antagonists. In contrast, IL-13 effector function increases dramatically in IL-13 receptor alpha2 (IL-13Ralpha2)-deficient mice. These mice develop severe hepatic fibrosis, fail to downregulate granuloma formation in the chronic phase of S. mansoni infection, and succumb to the disease at an accelerated rate; thus, identifying the 'decoy' IL-13 receptor as a critical life sustaining 'off' switch for tissue damaging egg-induced inflammation.

Lymphomagenesis, hydronephrosis, and autoantibodies result from dysregulation of IL-9 and are differentially dependent on Th2 cytokines

Interleukin-9 is an immunoregulatory cytokine implicated in the development of asthma and allergy. To investigate the role of IL-9 in vivo, we have generated transgenic mice in which IL-9 is expressed from its own promoter. Strikingly, overexpression of IL-9 resulted in premature mortality associated with a complex phenotype characterized by the development of autoantibodies, hydronephrosis, and T cell lymphoma. By intercrossing IL-9 transgenic mice with a panel of Th2 cytokine-deficient mice, we demonstrate that these disorders represent distinct phenotypes that can be dissociated by their differential dependence on Th2 cytokines. Autoantibody production was ablated in IL-9 transgenic animals with a combined absence of IL-4, IL-5, and IL-13, coincident with a reduction in peritoneal B-1 cells. Hydronephrosis arose in 75% of IL-9 transgenic animals and was dependent on the presence of IL-4 and IL-13. In contrast, T cell lymphomas developed independently of the other Th2 cytokines, with the generation of rapidly proliferating CD8(+) or CD4(+)CD8(+) T cell clones that arose in the thymus before infiltrating both lymphoid and nonlymphoid tissues. Our data highlight potentially important new roles for IL-9, through its regulation of downstream Th2 effector cytokines, in autoantibody production and in hydronephrosis.

CD4+ TCR repertoire heterogeneity in Schistosoma mansoni-induced granulomas

The hallmark of Schistosoma mansoni infection is the formation of liver granulomas around deposited ova. The initiation of granuloma formation is T cell-dependent since granulomas are not formed in their absence. We investigated whether a few T cells arrive to initiate the inflammatory lesion and subsequently expand locally, or whether a large repertoire of systemically activated T cells home to the delayed type hypersensitivity reaction induced by the ova. The TCR repertoire of single granulomas from the same liver were analyzed by PCR using Vbeta-specific primers and CDR3 analysis. Each granuloma has a very diverse TCR repertoire indicating that most of the T cells recruited to these lesions are activated systemically. At the same time, sequence analysis of individually sized CDR3 products from single granuloma indicate that a fraction of T cells expand locally at the lesion site. Using TCR transgenic mice containing a pigeon cytochrome c-specific T cell population or lymphocytic choriomeningitis virus infection tracked with lymphocytic choriomeningitis virus-specific tetramers, we demonstrated that nonspecific T cells home to the granuloma if they are activated. However, recombinase-activating gene 2(-/-) pigeon cytochrome c-specific TCR transgenic mice fail to form granulomas in response to S. mansoni ova even after T cell activation, suggesting a requirement for egg-specific T cells in the initiation of these inflammatory lesions. Understanding the mechanism of T cell recruitment into granulomas has important implications for the rational design of immunotherapies for granulomatous diseases.

Experimental models of Schistosoma mansoni infection

Experimental models of Schistosoma mansoni infections in mammals have contributed greatly to our understanding of the pathology and pathogenesis of infection. We consider here hepatic and extrahepatic disease in models of acute and chronic infection. Experimental schistosome infections have also contributed more broadly to our understanding of granulomatous inflammation and our understanding of Th1 versus Th2 related inflammation and particularly to Th2-mediated fibrosis of the liver.

Evolving pathophysiologic models of functional gastrointestinal disorders

In contrast to most other disorders of the digestive system, functional disorders of the gut continue to be defined by symptom criteria rather than by biological markers. At the same time, animal models of functional gastrointestinal disorders in which to test pathophysiologic hypotheses are lacking. The aim of this report is to critically review recently proposed conceptual as well as animal models of functional gastrointestinal disorders. Converging disease models have been proposed that postulate an enhanced responsiveness of neural, immune, or neuroimmune circuits in the central nervous system or in the gut to exteroceptive (psychosocial) or interoceptive (tissue irritation, inflammation, infection) perturbations of the organism's homeostasis. The enhanced responsiveness results in dysregulation of gut motility, epithelial function (immune, permeability), and visceral hypersensitivity, which in turn produce irritable bowel syndrome symptoms. These conceptual models provide plausible mechanisms for irritable bowel syndrome symptom generation and are consistent with extensive epidemiologic and pathophysiologic data. Several animal models have recently been proposed that mimic key features of these conceptual disease models. They fall into models triggered by centrally targeted stimuli (neonatal stress, post-traumatic stress disorder) or those triggered by peripherally targeted stimuli (infection, inflammation). Depending on the timing of the trigger (neonatal vs. adult), the changes induced in the animal may be permanent or transient. Future development of existing and novel models involves the use of transgenic and knockout animals, as well as the demonstration of predictive validity in terms of responsiveness to candidate drugs.