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Chen SN, Tan Y, Xiao XC, Li Q, Wu Q, Peng YY, Ren J, Dong ML. Deletion of TLR4 attenuates lipopolysaccharide-induced acute liver injury by inhibiting inflammation and apoptosis. Acta Pharmacol Sin 2021; 42:1610-1619. [PMID: 33495514 PMCID: PMC8463538 DOI: 10.1038/s41401-020-00597-x] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Accepted: 12/13/2020] [Indexed: 02/07/2023] Open
Abstract
Septic acute liver injury is one of the leading causes of fatalities in patients with sepsis. Toll-like receptor 4 (TLR4) plays a vital role in response to lipopolysaccharide (LPS) challenge, but the mechanisms underlying TLR4 function in septic injury remains unclear. In this study, we investigated the role of TLR4 in LPS-induced acute liver injury (ALI) in mice with a focus on inflammation and apoptosis. Wild-type (WT) and TLR4-knockout (TLR4-/-) mice were challenged with LPS (4 mg/kg) for 6 h. TLR4 signaling cascade markers (TLR4, MyD88, and NF-κB), inflammatory markers (TNFα, IL-1β, and IL-6), and apoptotic markers (Bax, Bcl-2, and caspase 3) were evaluated. We showed that LPS challenge markedly increased the levels of serum alanine aminotransferase (ALT)/aspartate aminotransferase (AST) and other liver pathological changes in WT mice. In addition, LPS challenge elevated the levels of liver carbonyl proteins and serum inflammatory cytokines, upregulated the expression of TLR4, MyD88, and phosphorylated NF-κB in liver tissues. Moreover, LPS challenge significantly increased hepatocyte apoptosis, caspase 3 activity, and Bax level while suppressing Bcl-2 expression in liver tissues. These pathological changes were greatly attenuated in TLR4-/- mice. Similar pathological responses were provoked in primary hepatic Kupffer cells isolated from WT and TLR4-/- mice following LPS (1 μg/mL, 6 h) challenge. In summary, these results demonstrate that silencing of TLR4 attenuates LPS-induced liver injury through inhibition of inflammation and apoptosis via TLR4/MyD88/NF-κB signaling pathway. TLR4 deletion confers hepatoprotection against ALI induced by LPS, possibly by repressing macrophage inflammation and apoptosis.
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Affiliation(s)
- Sai-Nan Chen
- Department of Critical Care Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China
- Department of Emergency Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Ying Tan
- Department of Critical Care Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Xiao-Chan Xiao
- Department of Emergency Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Qian Li
- Department of Emergency Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Qi Wu
- Department of Burns, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - You-You Peng
- Shanghai Hongrun Boyuan School, Shanghai, 201713, China
| | - Jun Ren
- Department of Cardiology, and Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital Fudan University, Shanghai, 200032, China.
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, 98195, USA.
| | - Mao-Long Dong
- Department of Burns, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China.
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