ABSTRACT
Wolbachia, an endosymbiont present in filarial nematodes, have been implicated in a variety of roles, including the worm development and survival. Elucidation of the role of Wolbachia in filarial nematode biology and pathogenesis has become the focus of many studies and its contribution to parasite survival or immune response is still unclear. Recombinant Wolbachia HSP60 decreases T cell activation and lymphoproliferation in filarial infected people compared to endemic controls as observed by the assessment of T cell activation markers and cytokine responses in the peripheral blood mononuclear cells. Reduced T cell activation may be linked to T regulatory cell activity since it is associated with increased expression of CTLA4 and CD25 on CD4(+) T cells in filarial infected group upon stimulation with recombinant Wolbachia HSP60. In addition, elevated interleukin-10 and TGF-ß cytokines corroborate the reduced CD4(+) T cell activation and interferon-γ observed upon recombinant Wolbachia HSP60 stimulation in filarial patients. Hence, these findings indicate that Wolbachia HSP60 may also contribute to the immune modulation seen in filarial patients.
Subject(s)
Bacterial Proteins/immunology , Brugia malayi/microbiology , Chaperonin 60/immunology , Elephantiasis, Filarial/immunology , Recombinant Proteins/immunology , T-Lymphocytes, Regulatory/immunology , Adolescent , Adult , Animals , Bacterial Proteins/genetics , Bacterial Proteins/pharmacology , Brugia malayi/immunology , CTLA-4 Antigen/immunology , Cells, Cultured , Chaperonin 60/genetics , Chaperonin 60/pharmacology , Child , Elephantiasis, Filarial/parasitology , Female , Humans , Immunomodulation/drug effects , Interferon-gamma/biosynthesis , Interferon-gamma/immunology , Interleukin-10/biosynthesis , Interleukin-10/immunology , Interleukin-2 Receptor alpha Subunit/immunology , Lymphocyte Activation/drug effects , Male , Recombinant Proteins/genetics , Recombinant Proteins/pharmacology , Symbiosis , T-Lymphocytes, Regulatory/drug effects , Transforming Growth Factor beta/biosynthesis , Transforming Growth Factor beta/immunology , Wolbachia/chemistry , Wolbachia/physiologyABSTRACT
Wolbachia surface protein (WSP), which is the most abundantly expressed protein of Wolbachia from the human filarial parasite Brugia malayi, was chosen for the present study. B-cell epitope prediction of the WSP protein sequence indicates a high antigenicity, surface probability and hydrophilicity by DNA STAR software analysis. ProPred analysis suggests the presence of HLA class II binding regions in the WSP protein that contribute to T-cell responses and isotype reactivity. In order to validate these findings, the gene coding for endosymbiont WSP was PCR-amplified from the genomic DNA of the human filarial parasite Brugia malayi and cloned in T-7 expression vector pRSET-A. Western blot and ELISA at the total IgG level with recombiant WSP indicated a significantly elevated reactivity in CP compared to MF, EN and NEN individuals. Isotype ELISA also suggested an elevated reactivity in CP patients at the IgG1 level. In contrast, WSP-specific IgG4 levels were found to be elevated in MF patients compared to CP and EN. Besides this, WSP-specific IgE levels indicated an elevated reactivity in CP and MF patients compared to normals. Observations from ELISA supported the in silico predictions that indicate the presence of B- and T-cell epitopes. Hence, a combinatorial approach of in silico predictions and wet-lab studies provides interesting insights into the role of Wolbachia proteins in filarial pathogenesis.
