Department of Medicine, Division of Gastroenterology
Amino Acids, Peptides, and Proteins | Cell Biology | Cells | Cellular and Molecular Physiology | Digestive System Diseases | Gastroenterology | Genetic Phenomena | Hepatology | Pathological Conditions, Signs and Symptoms
Alcoholic liver disease (ALD) is characterized by macrophage and neutrophil leukocyte recruitment and activation in the liver. Damage- and pathogen-associated molecular patterns contribute to a self-perpetuating proinflammatory state in ALD. Triggering receptor expressed on myeloid cells 1 (TREM-1) is a surface receptor that amplifies inflammation induced by toll-like receptors (TLRs) and is expressed on neutrophils and monocytes/macrophages. We hypothesized that TREM-1 signaling contributes to proinflammatory pathway activation in ALD. Using an in vivo ALD model in mice, we tested the effects of ligand-independent TREM-1 inhibitory peptides that were formulated into human high-density lipoprotein (HDL)-mimicking complexes GF9-HDL and GA/E31-HDL. As revealed in vitro, macrophages endocytosed these rationally designed complexes through scavenger receptors. A 5-week alcohol feeding with the Lieber-DeCarli diet in mice resulted in increased serum alanine aminotransferase (ALT), liver steatosis, and increased proinflammatory cytokines in the liver. TREM-1 messenger RNA (mRNA) expression was significantly increased in alcohol-fed mice, and TREM-1 inhibitors significantly reduced this increase. TREM-1 inhibition significantly attenuated alcohol-induced spleen tyrosine kinase (SYK) activation, an early event in both TLR4 and TREM-1 signaling. The TREM-1 inhibitors significantly inhibited macrophage (epidermal growth factor-like module-containing mucin-like hormone receptor-like 1 [F4/80], clusters of differentiation [CD]68) and neutrophil (lymphocyte antigen 6 complex, locus G [Ly6G] and myeloperoxidase [MPO]) markers and proinflammatory cytokines (monocyte chemoattractant protein 1 [MCP-1], tumor necrosis factor alpha [TNF-alpha], interleukin-1beta [IL-1beta], macrophage inflammatory protein 1alpha [MIP-1alpha]) at the mRNA level compared to the HDL vehicle. Administration of TREM-1 inhibitors ameliorated liver steatosis and early fibrosis markers (alpha-smooth muscle actin [alphaSMA] and procollagen1alpha [Pro-Col1alpha]) at the mRNA level in alcohol-fed mice. However, the HDL vehicle also reduced serum ALT and some cytokine protein levels in alcohol-fed mice, indicating HDL-related effects. Conclusion: HDL-delivered novel TREM-1 peptide inhibitors ameliorate early phases of inflammation and neutrophil and macrophage recruitment and activation in the liver and attenuate hepatocyte damage and liver steatosis. TREM-1 inhibition represents a promising therapeutic approach for further investigations in ALD.
alcoholic liver disease
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© 2018 The Authors. Hepatology Communications published by Wiley Periodicals, Inc., on behalf of the American Association for the Study of Liver Diseases. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
DOI of Published Version
Hepatol Commun. 2018 Oct 29;3(1):99-115. doi: 10.1002/hep4.1269. eCollection 2019 Jan. Link to article on publisher's site
Tornai, David; Furi, Istvan; Shen, Zu T.; Sigalov, Alexander B.; Coban, Sahin; and Szabo, Gyongyi, "Inhibition of Triggering Receptor Expressed on Myeloid Cells 1 Ameliorates Inflammation and Macrophage and Neutrophil Activation in Alcoholic Liver Disease in Mice" (2018). Open Access Articles. 3728.
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