Leishmaniasis, the second most neglected
tropical disease, has
been reported to affect approximately 12 million people worldwide.
The causative protozoan parasite Leishmania has shown
drug resistance to available chemotherapies, owing to which we need
to look for better approaches to deal with the clinical situations.
As per recent reports, several miRNAs have been found to be differentially
expressed during Leishmania major infection
in host macrophages. We aim to evaluate the impact of miRNA-mediated
gene regulation on the key players of inflammation and macrophage
dysfunction. The origin of Leishmania miRNAs and
their processing is a questionable phenomenon as of yet. Through our
study, we aim to provide a framework of their characterization. We
amalgamate chemical systems biology and synthetic biology approaches
to identify putative miRNA targets and unravel the complexity of host–pathogen
gene regulatory networks.
Autophagy is a self-destructing mechanism of cell via lysosomal degradation, which helps to degrade/ destroy hazardous substances, proteins, degenerating organelles and recycling nutrient. It plays an important role in cellular homeostasis and regulates internal environment of cell, moreover, when needed causes non-apoptotic programmed death of cell. It's usually detailed with ageing and nutritional stress, but recent researches provide support for its role in innate as well as adaptive immunity. Autophagy has been observed as one of the major factors in parasite clearance in leishmaniasis. Due to intra-cellular pathogen, the cell mediated response is only alternative for adaptive immunity against Leishmania in host. T-cells have been observed as main component of cell mediated immunity in leishmaniasis. The differentiation of T-cells generates either destruction or proliferation of parasite as different kind of cytokine mediate different results. Pro-inflammatory cytokine IL12 and TNFα generate Th2 response which helps in active phagocytosis of parasite whereas an anti-inflammatory cytokine like IL10 mediate parasite promotion by blocking autophagic pathways and inhibiting phagocytic actions. TLR2/6 mediated signaling stimulated by LPG produces many pro-inflammatory cytokines like IL12, TNFα and IL6 etc. In macrophages, it is found that TNFα via autocrine signaling induce autophagy and help in parasite killing of Toxoplasma gondii via JNK phosphorylation in macrophages. The phosphorylated JNK induces Beclin by phosphorylating Bcl2, which inhibits Beclin action, thus releasing Beclin and promoting VpS34 which recruits PI3P for autophagosome formation. Recruitment of PI3P is controlled by ATG9 protein, autophagy related gene protein, which in normal condition is inhibited by mTOR via ULK/ ATG1. IL10 has been observed to inhibit autophagy via starvation induced AKT-PI3K pathway in macrophages and result in inducing mTOR. Thus, we can conclude that IL10 inhibits recruitment of PI3P via mTOR. Through systems aspect, here, we decipher that Atg9-PI3P acts as a negative feedback loop in autophagic machinery of leishmaniasis.
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