The damage-associated molecular pattern HMGB1 is elevated in human alcoholic hepatitis, but does not seem to be a primary driver of inflammation TEA LUND LAURSEN, 1 SIDSEL STØY, 1 BENT DELEURAN, 2 HENDRIK VILSTRUP, 1 HENNING GRØNBÆK 1 and THOMAS DAMGAARD SANDAHL 1 1 Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus; and 2 Department of Biomedicine, Aarhus University, Aarhus, Denmark Laursen TL, Støy S, Deleuran B, Vilstrup H, Grønbæk H, Sandahl TD. The damage-associated molecular pattern HMGB1 is elevated in human alcoholic hepatitis, but does not seem to be a primary driver of inflammation. APMIS 2016; 124: 741–747. The role of sterile inflammation caused by release of damage-associated molecular patterns (DAMP) remains unclear in human alcoholic hepatitis (AH). The DAMP, high mobility group box-1 protein (HMGB1) is released by tissue dam- age and inflammation. We aimed to investigate whether HMGB1 is a primary inflammatory driver in AH by determin- ing HMGB1 serum levels and effects on inflammatory cells from AH patients. We measured serum HMGB1 in 34 AH patients and 10 healthy controls using ELISA. Toll-like receptor 4 (TLR4) and CD14 expressions were assessed by flow cytometry on HMGB1-stimulated peripheral blood mononuclear cells (PBMC) and ELISA was used to measure TNF-a and IL-1b in the supernatants. We observed 5-fold higher serum levels of HMGB1 in AH patients at the day of diagnosis and day 30, but no associations to clinical outcome. HMGB1 stimulation increased the expression of TLR4 on CD14+-monocytes compared with unstimulated cells in the AH patients. The TNF-a and IL-1b production in response to HMGB1 was diminished in AH patients. In conclusion, AH patients have increased levels of HMGB1 in their blood. This combined with an increased TLR4 expression, but an unaffected cytokine response to HMGB1 sug- gest that HMGB1 is not the primary driver of inflammation in AH. Key words: Alcoholic hepatitis; high mobility group box-1 protein; IL-1b; TNF-a and Toll-like receptor 4. Tea Lund Laursen, Department of Hepatology and Gastroenterology, Aarhus University Hospital, 44 Nørrebrogade, Building 1C, DK-8000 Aarhus C, Denmark. e-mail: tealaurs@rm.dk Alcoholic hepatitis (AH) is a severe disease and patients often rapidly deteriorate with a poor prog- nosis (1). Despite extensive investigations, it remains unclear what drives the inflammation and why current anti-inflammatory treatments are insuf- ficient. Gut-derived pathogen-associated molecular patterns (PAMPs), like lipopolysaccharide (LPS), are currently considered central in initiating and maintaining the hepatic inflammation in AH (2–4). However, recently, sterile inflammation with the release of damage-associated molecular patterns (DAMP) has been suggested as a potential driver of inflammation (5). The extensive hepatic injury leads to the release of DAMPs, which may induce, maintain, or exacerbate hepatic inflammation and injury in AH. One important DAMP is the high mobility group box-1 protein (HMGB1), a non-his- tone nuclear protein found in most cell types and involved in the regulation of gene transcription. HMGB1 can be released into the blood stream either from monocytes, macrophages, or dendritic cells as part of an inflammatory response. Cell damage or necrosis/apoptosis will cause its release from any cell type (6, 7). The functions of extracel- lular HMGB1 depend on the state of oxidation of the HMGB1 protein. It may hold either chemokine activity attracting inflammatory cells or act as a damage-associated molecular pattern that may induce cytokine production and release (8, 9). HMGB1, like LPS, can act via toll-like receptor 4 (TLR4) in combination with CD14 on the surface of monocytes (10, 11). High levels of HMGB1 in serum have been detected in the setting of acute liver failure (ALF) Received 8 March 2016. Accepted 18 May 2016 741 APMIS 124: 741–747 © 2016 APMIS. Published by John Wiley & Sons Ltd. DOI 10.1111/apm.12568