scholarly journals Helminth parasites and immune regulation

F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 1685 ◽  
Author(s):  
Pedro H. Gazzinelli-Guimaraes ◽  
Thomas B. Nutman
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Regulatory T Cells ◽  
Immune Responses ◽  
Immune Regulation ◽  
Chronic Infection ◽  
Metabolic Disorders ◽  
Helminth Infection ◽  
Host Cells ◽  
Helminth Parasites

Helminth parasites are complex metazoans that belong to different taxonomic families but that collectively share the capacity to downregulate the host immune response directed toward themselves (parasite-specific immunoregulation). During long-standing chronic infection, these helminths appear able to suppress immune responses to bystander pathogens/antigens and atopic, autoimmune, and metabolic disorders. Helminth-induced immunoregulation occurs through the induction of regulatory T cells or Th2-type cells (or both). However, secreted or excreted parasite metabolites, proteins, or extracellular vesicles (or a combination of these) may also directly induce signaling pathways in host cells. Therefore, the focus of this review will be to highlight recent advances in understanding the immune responses to helminth infection, emphasizing the strategies/molecules and some of the mechanisms used by helminth parasites to modulate the immune response of their hosts.

The role of cytokines in immunological tolerance: potential for therapy

2000 ◽  
Vol 2 (9) ◽  
pp. 1-20 ◽  
Author(s):  
Mark Harber ◽  
Anette Sundstedt ◽  
David Wraith
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Immune System ◽  
Animal Models ◽  
Regulatory T Cells ◽  
Immune Responses ◽  
Immunological Tolerance ◽  
Immunomodulatory Effects ◽  
Clinical Potential

Current immunosuppression protocols, although often effective, are nonspecific and therefore hazardous. Consequently, immunological tolerance that is antigen specific and does not globally depress the patient's immune system has become one of the Holy Grails of immunology. Since the discovery that cytokines have immunomodulatory effects, extensive research has investigated the potential of these molecules to induce and maintain specific immunological tolerance in the context of transplantation, allergy and autoimmunity. In this article, we review the possible mechanisms by which cytokines can modulate the immune response and the animal models that frequently confound the theory that a single cytokine, or group of cytokines, can induce tolerance in a predictable manner. Finally, we discuss the role of cytokines at a paracrine level, particularly in the context of inducing and maintaining antigen-specific, regulatory T cells with the clinical potential to suppress specific immune responses.

scholarly journals The Blockade of Interleukin-2 During the Acute Phase of Trypanosoma cruzi Infection Reveals Its Dominant Regulatory Role

2021 ◽  
Vol 11 ◽  
Author(s):  
Jorge Nihei ◽  
Fabiola Cardillo ◽  
Jose Mengel
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Regulatory T Cells ◽  
Trypanosoma Cruzi ◽  
Immune Responses ◽  
Chagas Disease ◽  
Acute Phase ◽  
Acute Infection ◽  
Dependent Manner ◽  
Tissue Specific

Trypanosoma cruzi infection causes Chagas’ disease in humans. The infection activates the innate and adaptative immunity in an orchestrated immune response to control parasite growth, guaranteeing host survival. Despite an effective immune response to the parasite in the acute phase, the infection progresses to a chronic stage. The parasite infects different tissues such as peripheral neurons, the brain, skeletal muscle, and heart muscle, among many others. It is evident now that tissue-specific immune responses may develop along with anti-parasite immunity. Therefore, mechanisms to regulate immunity and to ensure tissue-specific tolerance are operating during the infection. Studying those immunoregulatory mechanisms is fundamental to improve host protection or control inflammatory reactions that may lead to pathology. The role of IL-2 during T. cruzi infection is not established. IL-2 production by T cells is strongly down-modulated early in the disease by unknown mechanisms and remains low during the chronic phase of the disease. IL-2 activates NK cells, CD4, and CD8 T cells and may be necessary to immunity development. Also, the expansion and maintenance of regulatory T cells require IL-2. Thus, IL-2 may be a key cytokine involved in promoting or down-regulating immune responses, probably in a dose-dependent manner. This study blocked IL-2 during the acute T. cruzi infection by using a neutralizing monoclonal antibody. The results show that parasitemia and mortality rate was lower in animals treated with anti-IL-2. The percentages and total numbers of CD4+CD25+Foxp3+ T cells diminished within three weeks of infection. The numbers of splenic activated/memory CD4 and CD8 splenic T cells increased during the acute infection. T cells producing IFN-γ, TNF-α and IL-10 also augmented in anti-IL-2-treated infected mice. The IL-2 blockade also increased the numbers of inflammatory cells in the heart and skeletal muscles and the amount of IL-17 produced by heart T cells. These results suggest that IL-2 might be involved in the immune regulatory response during the acute T. cruzi infection, dampening T cell activation through the expansion/maintenance of regulatory T cells and regulating IL-17 production. Therefore, the IL-2 pathway is an attractive target for therapeutic purposes in acute and chronic phases of Chagas’ disease.

scholarly journals Immunity against Helminths: Interactions with the Host and the Intercurrent Infections

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Emmanuelle Moreau ◽  
Alain Chauvin
Keyword(s):  
Immune Response ◽  
Immune System ◽  
Immune Responses ◽  
Chronic Infection ◽  
Inflammatory Diseases ◽  
Economic Importance ◽  
Host Immune System ◽  
Helminth Parasites ◽  
Strong Immune Response ◽  
Helminth Infections

Helminth parasites are of considerable medical and economic importance. Studies of the immune response against helminths are of great interest in understanding interactions between the host immune system and parasites. Effector immune mechanisms against tissue-dwelling helminths and helminths localized in the lumen of organs, and their regulation, are reviewed. Helminth infections are characterized by an association of Th2-like and Treg responses. Worms are able to persist in the host and are mainly responsible for chronic infection despite a strong immune response developed by the parasitized host. Two types of protection against the parasite, namely, premune and partial immunities, have been described. Immune responses against helminths can also participate in pathogenesis. Th2/Treg-like immunomodulation allows the survival of both host and parasite by controlling immunopathologic disorders and parasite persistence. Consequences of the modified Th2-like responses on co-infection, vaccination, and inflammatory diseases are discussed.

scholarly journals Regulatory T Cells and the Control of the Allergic Response

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Ana Agua-Doce ◽  
Luis Graca
Keyword(s):  
T Cells ◽  
Regulatory T Cells ◽  
Immune Responses ◽  
Immune Regulation ◽  
Allergic Diseases ◽  
Active Role ◽  
Regulatory Mechanisms ◽  
Healthy Individuals ◽  
Biological Drugs

The study of immune regulation and tolerance has been traditionally associated with self/nonself-discrimination. However, the finding that dominant tolerance, a model that puts in evidence the active role of regulatory T cells, can develop to nonself-antigens suggests that the imposition of tolerance can be context dependent. This paper reviews the emerging field of acquired immune tolerance to non-self antigens, with an emphasis on the different subsets of induced regulatory T cells that appear to specialize in specific functional niches. Such regulatory mechanisms are important in preventing the onset of allergic diseases in healthy individuals. In addition, it may be possible to take advantage of these immune regulatory mechanisms for the induction of tolerance in cases where pathological immune responses are generated to allergens occurring in nature, but also to other immunogens such as biological drugs developed for medical therapies.

scholarly journals Infected site-restricted Foxp3+ natural regulatory T cells are specific for microbial antigens

2006 ◽  
Vol 203 (3) ◽  
pp. 777-788 ◽  
Author(s):  
Isabelle J. Suffia ◽  
Stacie K. Reckling ◽  
Ciriaco A. Piccirillo ◽  
Romina S. Goldszmid ◽  
Yasmine Belkaid
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Dendritic Cells ◽  
Regulatory T Cells ◽  
Chronic Infection ◽  
Leishmania Major ◽  
Foxp3 Expression ◽  
Antigen Recognition ◽  
Antigenic Specificity ◽  
Self Antigen

Natural regulatory T (T reg) cells are involved in control of the immune response, including response to pathogens. Previous work has demonstrated that the repertoire of natural T reg cells may be biased toward self-antigen recognition. Whether they also recognize foreign antigens and how this recognition contributes to their function remain unknown. Our studies addressed the antigenic specificity of natural T reg cells that accumulate at sites of chronic infection with Leishmania major in mice. Our results support the idea that natural T reg cells are able to respond specifically to foreign antigens in that they strongly proliferate in response to Leishmania-infected dendritic cells, they maintain Foxp3 expression, and Leishmania-specific T reg cell lines can be generated from infected mice. Surprisingly, the majority of natural T reg cells at the infected site are Leishmania specific. Further, we showed that parasite-specific natural T reg cells are restricted to sites of infection and that their survival is strictly dependent on parasite persistence.

scholarly journals Infection with the Helminth Nippostrongylus brasiliensis Does Not Interfere with Efficient Elimination of Mycobacterium bovis BCG from the Lungs of Mice

2002 ◽  
Vol 9 (3) ◽  
pp. 727-730 ◽  
Author(s):  
Klaus J. Erb ◽  
Claudia Trujillo ◽  
Mike Fugate ◽  
Heidrun Moll
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Immune Responses ◽  
Mycobacterium Bovis ◽  
Helminth Infection ◽  
Nippostrongylus Brasiliensis ◽  
Th2 Response ◽  
Th2 Responses ◽  
The Impact ◽  
Th1 Immune Response

ABSTRACT Infection with Mycobacterium tuberculosis continues to be one of the major global health threats. Strong mycobacterium-specific Th1 immune responses correlate with protection, and decreased Th1 responses correlate with disease progression. In contrast, the impact of Th2 responses on the development of protective immune responses to mycobacteria remains unclear. To analyze whether ongoing Th2 responses present in the lung influence the development of a protective Th1 immune response to mycobacteria, we coinfected mice with the helminth Nippostrongylus brasiliensis and Mycobacterium bovis BCG. We found that the T cells from the lymph nodes of coinfected mice secreted significantly less gamma interferon than did the T cells from mice infected with M. bovis BCG after in vitro stimulation with purified protein from M. tuberculosis when 108 CFU of M. bovis BCG were used for the infection. This result indicates that the helminth infection reduced the Th1 immune response to the mycobacteria in the lung. However, mycobacterial clearance was not delayed in the coinfected animals. Importantly, the infection with BCG after the helminth infection did not reduce the helminth-induced Th2 response in the lung, ruling out the possibility that the lack of a reduction in bacterial clearance in the coinfected mice was due to a downmodulation of the helminth-induced Th2 response. Taken together, our results suggest that ongoing Th2 responses in the lung do not necessarily lead to increased susceptibility to mycobacterial infection.

scholarly journals Regulatory T Cells in Autoimmune and Viral Chronic Hepatitis

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Pascal Lapierre ◽  
Alain Lamarre
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Liver Disease ◽  
T Cell ◽  
Regulatory T Cells ◽  
Immune Responses ◽  
Autoimmune Hepatitis ◽  
Viral Hepatitis ◽  
Chronic Viral Hepatitis ◽  
Autoimmune Liver Disease

In both autoimmune liver disease and chronic viral hepatitis, the injury results from an immune-mediated cytotoxic T cell response to liver cells. As such, it is not surprising that CD4+regulatory T cells, a key regulatory population of T cells able to curb immune responses, could be involved in both autoimmune hepatitis and chronic viral hepatitis. The liver can induce the conversion of naïve CD4+T cells to CD4+regulatory T cells and induce tolerance to locally expressed antigens. This tolerance mechanism is carefully regulated in physiological conditions but any imbalance could be pathological. An overly tolerant immune response can lead to chronic infections while an overreactive and unbridled immune response can lead to autoimmune hepatitis. With the recent advent of monoclonal antibodies able to target regulatory T cells (daclizumab) and improve immune responses and several ongoing clinical trials analysing the impact of regulatory T cell infusion on autoimmune liver disease or liver transplant tolerance, modulation of immunological tolerance through CD4+regulatory T cells could be a key element of future immunotherapies for several liver diseases allowing restoring the balance between proper immune responses and tolerance.  

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