Autophagy protects monocytes from Wolbachia heat shock protein 60-induced apoptosis and senescence.

Monocyte dysfunction by filarial antigens has been a major mechanism underlying immune evasion following hyporesponsiveness during patent lymphatic filariasis. Recent studies have initiated a paradigm shift to comprehend the immunological interactions of Wolbachia and its antigens in inflammation, apoptosis, lymphocyte anergy, etc. Here we showed that recombinant Wolbachia heat shock protein 60 (rWmhsp60) interacts with TLR-4 and induces apoptosis in monocytes of endemic normal but not in chronic patients. Higher levels of reactive oxygen species (ROS) induced after TLR-4 stimulation resulted in loss of mitochondrial membrane potential and caspase cascade activation, which are the plausible reason for apoptosis. Furthermore, release in ROS owing to TLR-4 signaling resulted in the activation of NF-κB p65 nuclear translocation which leads to inflammation and apoptosis via TNF receptor pathway following the increase in IL-6 and TNF-α level. Here for the first time, we report that in addition to apoptosis, rWmhsp60 antigen in filarial pathogenesis also induces molecular senescence in monocytes. Targeting TLR-4, therefore, presents a promising candidate for treating rWmhsp60-induced apoptosis and senescence. Strikingly, induction of autophagy by rapamycin detains TLR-4 in late endosomes and subverts TLR-4-rWmhsp60 interaction, thus protecting TLR-4-mediated apoptosis and senescence. Furthermore, rapamycin-induced monocytes were unresponsive to rWmhsp60, and activated lymphocytes following PHA stimulation. This study demonstrates that autophagy mediates the degradation of TLR-4 signaling and protects monocytes from rWmhsp60 induced apoptosis and senescence.

Functional Characterization of a c-type Lysozyme from Indian Shrimp Fenneropenaeus indicus.

Lysozyme gene from Fenneropenaeus indicus was cloned, expressed in Escherichia coli and characterized. The cDNA consists of 477 base pairs and encodes amino acid sequence of 159 residues. F. indicus lysozyme had high identity (98%) with Fenneropenaeus merguiensis and Fenneropenaeus chinensis and exhibits low to moderate identities with lysozymes of other invertebrates and vertebrates. This lysozyme is presumed to be chicken types as it possesses two catalytic and eight cysteine residues that are conserved across c-type lysozymes and a c-terminal extension, which is a characteristic of lysozymes from marine invertebrates. Further, the antimicrobial properties of the recombinant lysozyme from F. indicus were determined in comparison with recombinant hen egg white lysozyme. This exhibited high activity against a Gram-negative pathogenic bacterium Salmonella typhimurium and two fungal strains Pichia pastoris and Saccharomyces cerevisiae in turbidimetric assay. Distribution of lysozyme gene and protein in tissues of shrimps infected with white spot syndrome virus revealed that the high levels of lysozyme are correlated with low and high viral load in abdominal muscle and tail, respectively. In conclusion, lysozyme from F. indicus has a broad spectrum of antimicrobial properties, which once again emphasizes its role in shrimp innate immune response.

Wolbachia heat shock protein 60 induces pro-inflammatory cytokines and apoptosis in monocytes in vitro.

Recombinant Wolbachia heat shock protein 60 (rWmhsp60) induces gene expression of pro-inflammatory cytokines IL-1ß, IL-6 and TNF-α in human monocytic cell line THP-1. In addition, it inhibits the phagocytic activity and does not alter the nitric oxide production by differentiated THP-1 macrophages, which corroborates with no significant change in inducible nitric oxide synthase gene expression in rWmhsp60 treated THP-1 monocytes. Further, 24 h stimulation of peripheral blood mononuclear cells from normal individuals by rWmhsp60 reveals that monocytes enter the late apoptotic stage, while lymphocytes do not show apoptosis. Thus these findings suggest that rWmhsp60 may contribute to inflammation mediated monocyte dysfunction in filarial pathogenesis.