Mincle Signaling in the Innate Immune Response after Traumatic Brain Injury
JOURNAL OF NEUROTRAUMA
Authors: Vaccari, Juan Carlos de Rivero; Brand, Frank J., III; Berti, Aldo F.; Alonso, Ofelia F.; Bullock, M. Ross; Vaccari, Juan Pablo de Rivero
Abstract
The innate immune response contributes to the inflammatory activity after traumatic brain injury (TBI). In the present study we identify macrophage-inducible C-type lectin (mincle) as a pattern recognition receptor that contributes to innate immunity in neurons after TBI. Here we report that mincle is activated by SAP130 in cortical neurons in culture, resulting in production of the inflammatory cytokine TNF. In addition, mincle and SAP130 are elevated in the brain and cerebrospinal fluid of humans after TBI and the brain of rodents after fluid percussion brain injury. Thus, these findings suggest the involvement of mincle to the pathology of TBI. Importantly, blocking mincle with a neutralizing antibody against mincle in cortical neurons in culture treated with SAP130 resulted in inhibition of mincle signaling and decreased TNF production. Therefore, our findings identify mincle as a contributor to the inflammatory response after TBI.
IRAKM-Mincle Axis Links Cell Death to Inflammation: Pathophysiological Implications for Chronic Alcoholic Liver Disease
HEPATOLOGY
Authors: Zhou, Hao; Yu, Minjia; Zhao, Junjie; Martin, Bradley N.; Roychowdhury, Sanjoy; McMullen, Megan R.; Wang, Emily; Fox, Paul L.; Yamasaki, Sho; Nagy, Laura E.; Li, Xiaoxia
Abstract
Lipopolysaccharide (LPS)-mediated activation of Toll-like receptors (TLRs) in hepatic macrophages and injury to hepatocytes are major contributors to the pathogenesis of alcoholic liver disease. However, the mechanisms by which TLR-dependent inflammatory responses and alcohol-induced hepatocellular damage coordinately lead to alcoholic liver disease are not completely understood. In this study, we found that mice deficient in interleukin-1 receptor-associated kinase M (IRAKM), a proximal TLR pathway molecule typically associated with inhibition of TLR signaling, were actually protected from chronic ethanol-induced liver injury. In bone marrow-derived macrophages challenged with low concentrations of LPS, which reflect the relevant pathophysiological levels of LPS in both alcoholic patients and ethanol-fed mice, the IRAKM Myddosome was preferentially formed. Further, the IRAKM Myddosome mediated the up-regulation of Mincle, a sensor for cell death. Mincle-deficient mice were also protected from ethanol-induced liver injury. The endogenous Mincle ligand spliceosome-associated protein 130 (SAP130) is a danger signal released by damaged cells; culture of hepatocytes with ethanol increased the release of SAP130. Ex vivo studies in bone marrow-derived macrophages suggested that SAP130 and LPS synergistically activated inflammatory responses, including inflammasome activation. Conclusion: This study reveals a novel IRAKM-Mincle axis that contributes to the pathogenesis of ethanol-induced liver injury.