Regulatory Networks Induced by Live Parasites Impair Both Th1 and Th2 Pathways in Patent Lymphatic Filariasis: Implications for Parasite Persistence

Babu, Subash and Blauvelt, C P and Kumaraswami, V and Nutman, T B (2006) Regulatory Networks Induced by Live Parasites Impair Both Th1 and Th2 Pathways in Patent Lymphatic Filariasis: Implications for Parasite Persistence. Journal of Immunology, 176 (5). pp. 3248-3256. ISSN Print: 0022-1767; Online: 1550-6606

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Abstract

Patent lymphatic filariasis is characterized by a profound down-regulation of immune responses with both parasite Ag-specific tolerance and bystander suppression. Although this down-regulation is confined to the Th1 arm of the immune system in response to parasite Ag, we hypothesized a more generalized suppression in response to live parasites. Indeed, when we examined the cytokine profile of a cohort of filaria-infected (n � 10) and uninfected (n � 10) individuals in response to live infective-stage larvae or microfilariae of Brugia malayi, we found significant impairment of both Th1 and Th2 cytokines characterized by diminished production of IFN-�, TNF-�, IL-4, IL-5, and IL-10 in infected patients. The molecular basis of this impaired Th1/Th2 response was examined, and we identified three major networks of immunoregulation and tolerance. First, impaired induction of T-bet and GATA-3 mRNA underlies the Th1/Th2 deficiency in infected individuals. Second, regulatory networks, as evidenced by significantly increased expression of Foxp3 (natural regulatory T cell marker) and regulatory effectors such as TGF-�, CTLA-4, PD-1, ICOS, and indoleamine 2,3-dioxygenase play an important role in immunosuppression. Third, the compromise of effector T cell function is mediated by the enhanced induction of anergy-inducing factors cbl-b, c-cbl (cbl is abbreviation for Casitas B lymphoma), Itch, and Nedd4. Indeed, blocking CTLA-4 or neutralizing TGF-� restored the ability to mount Th1/Th2 responses to live parasites and reversed the induction of anergy-inducing factors. Hence, we conclude that a profound impairment of live parasitespecific Th1 and Th2 immune responses occurs in lymphatic filariasis that is governed at the transcriptional level by a complex interplay of inhibitory mediators.

Item Type: Article
Subjects: Filariasis
Divisions: Basic Science Research > Immunology
Depositing User: Rathinasabapati R
Date Deposited: 02 Dec 2013 09:30
Last Modified: 09 Mar 2016 05:23
URI: http://eprints.nirt.res.in/id/eprint/740

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