1. Mycobacterium tuberculosis EsxL induces TNF-α secretion through activation of TLR2 dependent MAPK and NF-κB pathways.
- Author
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Pattanaik KP, Ganguli G, Naik SK, and Sonawane A
- Subjects
- Animals, MAP Kinase Signaling System, Macrophages immunology, Macrophages metabolism, Mice, Mycobacterium tuberculosis metabolism, NF-kappa B metabolism, Phosphorylation, RAW 264.7 Cells, Toll-Like Receptor 2 metabolism, p38 Mitogen-Activated Protein Kinases metabolism, Bacterial Proteins physiology, Tumor Necrosis Factor-alpha metabolism, Type VII Secretion Systems physiology
- Abstract
Mycobacterium tuberculosis (Mtb) employs distinct strategies to circumvent host immune responses during the infection process. Various Mtb cell-wall associated and secretory proteins are known to play a critical role in the orchestration of host innate immune responses through modulation of signaling pathways. Mtb genome encodes for 23 (EsxA-EsxW) proteins belonging to the ESAT-6 like family; however, most of them are functionally unknown. Here, we show that Mtb EsxL induces tumor necrosis factor-alpha (TNF-α) production by activating nuclear translocation of nuclear factor-κB (NF-κB) via interaction with Toll-like Receptor 2 (TLR2). Blocking or silencing of TLR2 abrogated nuclear translocation of NF-kB and TNF-α production. Treatment with recombinant purified EsxL (rEsxL) activated mitogen-activated protein kinase (MAPK) pathway by inducing the phosphorylation of extracellular signal-regulated kinase (ERK) and p38 kinase (p38) pathways. At the same time, inhibition of ERK and p38 down-regulated the expression of TNF-α in rEsxL exposed murine macrophages. Besides TNF-α, EsxL also induced the production of IL-6 proinflammatory cytokine. Taken together, these results suggest that EsxL is able to induce TNF-α secretion via TLR2 through activation of NF-κB and MAPK signaling. This study will help in deducing therapeutic strategies for better control of the disease., (Copyright © 2020. Published by Elsevier Ltd.)
- Published
- 2021
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