1. TLR22-mediated activation of TNF-α-caspase-1/IL-1β inflammatory axis leads to apoptosis of Aeromonas hydrophila-infected macrophages.
- Author
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Kumar M, Kumar J, Sharma S, Hussain MA, Shelly A, Das B, Yadav AK, and Mazumder S
- Subjects
- Animals, Caspases immunology, Catfishes immunology, Catfishes microbiology, Fish Diseases immunology, Fish Diseases microbiology, Fish Proteins immunology, Gram-Negative Bacterial Infections microbiology, Head Kidney immunology, Head Kidney microbiology, Inflammation microbiology, Interleukin-1beta immunology, Macrophages microbiology, Tumor Necrosis Factor-alpha immunology, Aeromonas hydrophila immunology, Apoptosis immunology, Gram-Negative Bacterial Infections immunology, Inflammation immunology, Macrophages immunology, Toll-Like Receptors immunology
- Abstract
Toll-like receptors (TLRs) represent first line of host defence against microbes. Amongst different TLRs, TLR22 is exclusively expressed in non-mammalian vertebrates, including fish. The precise role of TLR22 in fish-immunity remains abstruse. Herein, we used headkidney macrophages (HKM) from Clarias gariepinus and deciphered its role in fish-immunity. Highest tlr22 expression was observed in the immunocompetent organ - headkidney; nonetheless expression in other tissues suggests its possible involvement in non-immune sites also. Aeromonas hydrophila infection up-regulates tlr22 expression in HKM. Our RNAi based study suggested TLR22 restricts intracellular survival of A. hydrophila. Inhibitor and RNAi studies further implicated TLR22 induces pro-inflammatory cytokines TNF-α and IL-1β. We observed heightened caspase-1 activity and our results suggest the role of TLR22 in activating TNF-α/caspase-1/IL-1β cascade leading to caspase-3 mediated apoptosis of A. hydrophila-infected HKM. We conclude, TLR22 plays critical role in immune-surveillance and triggers pro-inflammatory cytokines leading to caspase mediated HKM apoptosis and pathogen clearance., (Copyright © 2021 Elsevier Ltd. All rights reserved.)
- Published
- 2021
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