Elsevier

Immunobiology

Volume 226, Issue 5, September 2021, 152129
Immunobiology

Infection by Strongyloides venezuelensis attenuates chronic colitis induced by Dextran Sodium Sulfate ingestion in BALB/c mice

https://doi.org/10.1016/j.imbio.2021.152129Get rights and content

Highlights

  • S. venezuelensis infection reduces the severity of DSS-induced chronic colitis.

  • Nematode infection increased Treg cells in DSS-exposed mice.

  • Colitis modulation was accompanied by increased TGF-β, IL-22, and IL-33.

  • S. venezuelensis infection preserves mucus production in DSS-exposed mice.

  • S. venezuelensis infection preserves colon integrity in DSS-exposed mice.

Abstract

Inflammatory bowel diseases (IBD) are chronic health problems of difficult management and treatment. Epidemiological studies indicate an inverse association between helminth infections and IBD, and experimental data confirm that helminth infections modulate the severity of experimental acute colitis in mice. However, the effects of helminth infections on chronic colitis, which is clinically more relevant, have been poorly explored. Herein, we investigated whether Strongyloides venezuelensis infection in BALB/c mice can ameliorate chronic colitis induced by the ingestion of water containing 2.5% Dextran Sodium Sulfate (DSS) over three seven-day treatment cycles, with an interval of fourteen days between cycles. Infected-only, DSS-exposed-only, and non-exposed/uninfected experimental groups served as controls for comparing the severity of colitis and intestinal inflammation among different groups. Our data showed that S. venezuelensis infection in mice with DSS-induced chronic colitis reduced clinical signs, attenuated colon shortening and inflammation, and prevented mucus ablation. The modulatory effect was accompanied by a low concentration of IFN-γ, high concentrations of TGF-β, IL-22, and IL-33 in the colon, and a significant increase of the percentage of CD4+CD25+Foxp3+ Treg cells in the mesenteric lymph node (MLN). In conclusion, S. venezuelensis infection can reduce the severity of DSS-induced chronic colitis in mice possibly through the stimulation of Treg cells and modulatory cytokines, and induction of mucosal repair mechanisms.

Graphical abstract

  1. Download : Download high-res image (176KB)
  2. Download : Download full-size image

Proposed model of the immune response induced by Strongyloides venezuelensis in the modulation of DSS-induced chronic colitis in BALB/c mice. Mucosa injury, caused by DSS-induced chronic colitis, allows the translocation of bacteria, which leads to an inflammatory infiltrate with the presence of eosinophils and neutrophils, accompanied by an increase in IFN-γ levels. The extensive inflammatory infiltration leads to a depletion of goblet cells and a consequent decrease in mucus production. S. venezuelensis infection in the small intestine induces differentiation of Treg cells in the mesenteric lymph node that can increase the production of TGF-β in the colon, which can reduce the infiltration of eosinophil and neutrophil in colon. In parallel, the nematode infection induces the production of IL-22 and IL-33 in the colon, thus leading to the preservation of goblet cells and contributing to the repair of the colon tissue.

Introduction

Inflammatory bowel diseases (IBD), including Crohn’s disease and ulcerative colitis, are characterized by relapsing chronic inflammation without a specific infectious or environmental cause (Legaki and Gazouli, 2016, Xavier and Podolsky, 2007). Although the pathogenesis of IBD remains unclear, studies indicate that genetic susceptibility and environmental factors contribute to a disruption of the intestinal tract homeostasis. As a consequence, the immune system can no longer distinguish pathogen antigens from the host’s antigens, commensal microbiota, and food, thus leading to an exacerbated immune response to these non-pathogenic antigens and the establishment of chronic intestinal inflammation (Ahluwalia et al., 2018, Halfvarson et al., 2003). The strategy for controlling these chronic inflammatory diseases generally depends on the long-term use of broad-spectrum corticosteroids or immunosuppressants, but not all patients respond well to these drugs and may suffer from their side effects (Motomura et al., 2009).

In 2017, it was estimated that there were 6.8 million cases of IBD in the world and, despite the increased incidence of IBD in some underdeveloped regions, the most dramatic increase was registered in developed countries (Alatab et al., 2019). Concomitant with the increased prevalence of IBD, there has been a rapid decline in helminth infection rates in developed countries (Elliott et al., 2000, Halfvarson et al., 2003). Supporting these epidemiological studies, experimental data from murine models have also demonstrated that infection by different species of helminths or inoculation of worm-derived antigens may reduce the severity of experimentally induced colitis (Varyani et al., 2017).

Indeed, previous data from our group showed that even an acute and transitory helminth infection, such as Strongyloides venezuelensis in mice, was capable of ameliorating the severity of DSS-induced acute colitis, which was accompanied by local reduction of inflammatory cytokine production and increased levels of IL-10 (Rodrigues et al., 2018). Nevertheless, the protective effects of helminth infections against experimental colitis are still controversial, and published data reported that some infections can lead to a worsening of the experimental colitis (Liu et al., 2018, Pastille et al., 2017, Wang et al., 2010). Moreover, randomized clinical studies in which patients with IBD were infected with Trichuris suis or Necator americanus showed conflicting results, with reports of IBD symptoms improving, remaining unchanged or worsening after infection (Croese et al., 2006, Garg et al., 2014, Huang et al., 2018, Summers et al., 2005).

Noteworthy, unlike clinical studies in which the experimental treatment using helminths was administrated in patients with chronic IBD, most of the experimental studies using animal models evaluated the preventive role of helminth infections or inoculation of worms-derived antigens on the induction of experimental acute colitis. There is little data related to the effects of helminth infections on the modulation of intestinal inflammation in experimental models of chronic colitis. Besides, putative mechanisms involved in the modulation of chronically established colitis by helminth infection are still unclear. Therefore, we tested whether S. venezuelensis infection can modulate the severity of chronic DSS-induced colitis in BALB/c mice. Our results revealed that the active infection with S. venezuelensis was able to decrease the severity of colon inflammation induced by chronic DSS ingestion in mice.

Section snippets

Animals

Female specific pathogen-free (SPF) BALB/c mice (six weeks old) mice were used. SPF mice were provided by the Animal Facility of the Federal University of Minas Gerais (UFMG, Brazil). During experimental procedures, mice were maintained at the Animal Facility for Helminth-Infected Animals of the Department of Parasitology (UFMG, Brazil), fed with standard laboratory chow (Presence, Paulínia, SP, Brazil), and provided with tap water ad libitum. The performed experimental procedures were

Prolonged exposure to DSS does not alter Strongyloides venezuelensis burden

Multiple cycles of DSS treatment did not alter S. venezuelensis infection load (Fig. 2). At day 7 post-infection, the number of adult worms recovered from the small intestines (Fig. 2A), the number of parasite eggs eliminated in feces (Fig. 2B), and the fecundity indexes (Fig. 2C) were statistically similar when comparing S. venezuelensis-infected (Sv) with the DSS-exposed and S. venezuelensis-infected (DSS-Sv) mice.

Strongyloides venezuelensis infection reduces the clinical signs of DSS-induced chronic colitis in mice

Chronic colitis was established following three cycles of 2.5% DSS

Discussion

Patients with IBD usually display a chronic condition that demands long-term prescriptions, shows poor curative effects, and produces serious side effects (Ahluwalia et al., 2018, Halfvarson et al., 2003). Although most of the experimental data reported that active helminth infections or their antigens have a preventive effect on experimentally induced colitis, their effect on chronically established models, which are clinically more relevant, are still unknown. Therefore, in the current study,

Conclusions

Based on our data and the published literature, we suggest that S. venezuelensis infection induces regulatory and repair mechanisms through the stimulation of Treg cells, TGF-β, IL-22, and IL-33, which reduce intestinal inflammation and granulocyte infiltration and induce mucus production and repair of the colon epithelium in a model of chronic colitis induced by prolonged exposure to DSS. These findings improve our understanding of the modulatory mechanisms induced by helminth infections and

CRediT authorship contribution statement

Vanessa Fernandes Rodrigues: Conceptualization, Methodology, Validation, Formal analysis, Investigation, Data curation, Writing – original draft, Writing - review & editing, Visualization. Genil Mororó Araújo Camelo: Methodology, Writing - review & editing. Michelle Carvalho de Rezende: Methodology. Laura Maggi: Methodology. Jeferson Kelvin Alves Oliveira Silva: Methodology. João Gustavo Mendes Rodrigues: Methodology. Márcio Sobreira Silva Araújo: Methodology, Formal analysis. Olindo Assis

Declaration of Competing Interest

Vanessa Fernandes Rodriguesa, Genil Mororó Araújo Camelo, Michelle Carvalho de Rezende, Laura Maggi, Jeferson Kelvin Alves Oliveira Silva, João Gustavo Mendes Rodrigues, Márcio Sobreira Silva Araújo, Olindo Assis Martins-Filho and Deborah Negrão-Corrêa declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in paper entitled “Infection by Strongyloides venezuelensis attenuates chronic colitis induced by

Acknowledgments

Financial support for reagents, equipment and fellowships used in this work was provided by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq-Brazil, grant # 481035/2012-5; grant #140160/2019-1), Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG-Brazil, grant # PPM-00500-15; # APQ-01637-17), and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES-Brazil, Basic Parasitology Program, grant # 23038.005297/2011-39, grant #88887.163351/2018-00).

Graphic abstract illustration credits

From Servier Medical Art (https://smart.servier.com/), reproduced under Creative Commons License attribution 3.0 Unported License.

References (61)

  • M.E. Rothenberg

    Eosinophilic gastrointestinal disorders (EGID)

    J. Allergy Clin. Immunol.

    (2004)
  • J. Schmitz et al.

    IL-33, an interleukin-1-like cytokine that signals via the IL-1 receptor-related protein ST2 and induces T helper type 2-associated cytokines

    Immunity

    (2005)
  • M. Strath et al.

    Detection of eosinophils using an eosinophil peroxidase assay. Its use as an assay for eosinophil differentiation factors

    J. Immunol. Methods

    (1985)
  • M. Van der Sluis et al.

    Muc2-deficient mice spontaneously develop colitis, indicating that MUC2 is critical for colonic protection

    Gastroenterology

    (2006)
  • A.T. Vieira et al.

    Treatment with a novel chemokine-binding protein or eosinophil lineage-ablation protects mice from experimental colitis

    Am. J. Pathol.

    (2009)
  • A. Wang et al.

    Exacerbation of oxazolone colitis by infection with the helminth Hymenolepis diminuta: Involvement of IL-5 and eosinophils

    Am. J. Pathol.

    (2010)
  • B. Ahluwalia et al.

    Immunopathogenesis of inflammatory bowel disease and mechanisms of biological therapies

    Scand. J. Gastroenterol.

    (2018)
  • S. Alatab et al.

    The global, regional, and national burden of inflammatory bowel disease in 195 countries and territories, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017

    Lancet Gastroenterol. Hepatol.

    (2019)
  • P. Alex et al.

    Distinct cytokine patterns identified from multiplex profiles of murine DSS and TNBS-induced colitis

    Inflamm. Bowel Dis.

    (2009)
  • A. Bressenot et al.

    Comparing histological activity indexes in UC

    Gut

    (2015)
  • A. Broquet et al.

    Interleukin-22 level is negatively correlated with neutrophil recruitment in the lungs in a Pseudomonas aeruginosa pneumonia model

    Sci. Rep.

    (2017)
  • L.J. Cliffe

    Accelerated intestinal epithelial cell turnover: a new mechanism of parasite expulsion

    Science (80-.

    (2005)
  • E.R. Cobo et al.

    MUC2 mucin and butyrate contribute to the synthesis of the antimicrobial peptide cathelicidin in response to Entamoeba histolytica- and dextran sodium sulfate-induced colitis

    Infect. Immun.

    (2017)
  • L.C. Coppi et al.

    Comparative study of eosinophil chemotaxis, adhesion, and degranulation in vitro in ulcerative colitis and Crohn’s disease

    Inflamm. Bowel Dis.

    (2007)
  • A. Cortés et al.

    Differential alterations in the small intestine epithelial cell turnover during acute and chronic infection with Echinostoma caproni (Trematoda)

    Parasit. Vectors

    (2015)
  • J. Croese et al.

    A proof of concept study establishing Necator americanus in Crohn’s patients and reservoir donors [8]

    Gut

    (2006)
  • F. Davey et al.

    Periodic Acid Schiff (PAS) Stain

  • D.E. Elliott et al.

    Does the failure to acquire helminthic parasites predispose to Crohn’s disease?

    FASEB J.

    (2000)
  • A. Fernandes et al.

    Evaluation of the immune response against Strongyloides venezuelensis in antigen-immunized or previously infected mice

    Parasite Immunol.

    (2008)
  • S. Garg et al.

    Helminth therapy (worms) for induction of remission in inflammatory bowel disease (Review) Summary of findings for the main comparison

    Cochrane Database Syst. ReC Cochrane D

    (2014)
  • Cited by (0)

    View full text