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Chakraborty, S. and Srivastava , A. and Jha , M.K. and Nair, A. and Pandey , S.P and Srivastava , N. and Kumari , S. and Singh , S. and Krishnasastry M.V.; Saha B. , M.V. and Saha , B. (2015) Inhibition of CD40-Induced N-Ras Activation Reduces Leishmania major Infection. Journal of Immunology , 194. pp. 3852-3860. ISSN Journal of Immunology

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Leishmania major is a parasite that resides and replicates in macrophages. We previously showed that the parasite enhanced CD40-induced Raf-MEK-ERK signaling but inhibited PI3K-MKK-p38MAPK signaling to proleishmanial effects. As Raf and PI3K have a Ras-binding domain but exert opposite effects on Leishmania infection, we examined whether Ras isoforms had differential roles in Leishmania infection. We observed that L. major enhanced N-Ras and H-Ras expression but inhibited K-Ras expression in macrophages. L. major infection enhanced N-Ras activity but inhibited H-Ras and K-Ras activity. TLR2 short hairpin RNA or anti-TLR2 or anti-lipophosphoglycan Abs reversed the L. major–altered N-Ras and K-Ras expressions. Pam3CSK4, a TLR2 ligand, enhanced N-Ras expression but reduced K-Ras expression, indicating TLR2-regulated Ras expression in L. major infection. Whereas N-Ras silencing reduced L. major infection, K-Ras and H-Ras silencing enhanced the infection both in macrophages in vitro and in C57BL/6 mice. BALB/c-derived macrophages transduced with lentivirally expressed N-Ras short hairpin RNA and pulsed with L. major–expressed MAPK10 enhanced MAPK10-specific Th1-type response. CD40-deficient mice primed with these macrophages had reduced L. major infection, accompanied by higher IFN-g but less IL-4 production. As N-Ras is activated by Sos, a guanine nucleotide exchange factor, we modeled the N-Ras–Sos interaction and designed two peptides from their interface. Both the cell-permeable peptides reduced L. major infection in BALB/c mice but not in CD40-deficient mice. These data reveal the L. major–enhanced CD40-induced N-Ras activation as a novel immune evasion strategy and the potential for Ras isoform–targeted antileishmanial immunotherapy and immunoprophylaxis.

Item Type: Article
Subjects: Infection and Immunity
Depositing User: Mr. Rameshwar Nema
Date Deposited: 11 May 2015 10:10
Last Modified: 14 May 2015 10:10
URI: http://nccs.sciencecentral.in/id/eprint/172

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