Expression of the Metalloproteinase ADAM8 Is Upregulated in Liver Inflammation Models and Enhances Cytokine Release In Vitro

Acute and chronic liver inflammation is driven by cytokine and chemokine release from various cell types in the liver. Here, we report that the induction of inflammatory mediators is associated with a yet undescribed upregulation of the metalloproteinase ADAM8 in different murine hepatitis models. We further show the importance of ADAM8 expression for the production of inflammatory mediators in cultured liver cells. As a model of acute inflammation, we investigated liver tissue from lipopolysaccharide- (LPS-) treated mice in which ADAM8 expression was markedly upregulated compared to control mice. In vitro, stimulation with LPS enhanced ADAM8 expression in murine and human endothelial and hepatoma cell lines as well as in primary murine hepatocytes. The enhanced ADAM8 expression was associated with an upregulation of TNF-α and IL-6 expression and release. Inhibition studies indicate that the cytokine response of hepatoma cells to LPS depends on the activity of ADAM8 and that signalling by TNF-α can contribute to these ADAM8-dependent effects. The role of ADAM8 was further confirmed with primary hepatocytes from ADAM8 knockout mice in which TNF-α and IL-6 induction and release were considerably attenuated. As a model of chronic liver injury, we studied liver tissue from mice undergoing high-fat diet-induced steatohepatitis and again observed upregulation of ADAM8 mRNA expression compared to healthy controls. In vitro, ADAM8 expression was upregulated in hepatoma, endothelial, and stellate cell lines by various mediators of steatohepatitis including fatty acid (linoleic-oleic acid), IL-1β, TNF-α, IFN-γ, and TGF-β. Upregulation of ADAM8 was associated with the induction and release of proinflammatory cytokines (TNF-α and IL-6) and chemokines (CX3CL1). Finally, knockdown of ADAM8 expression in all tested cell types attenuated the release of these mediators. Thus, ADAM8 is upregulated in acute and chronic liver inflammation and is able to promote inflammation by enhancing expression and release of inflammatory mediators

PANC Study (Pancreatitis: A National Cohort Study): national cohort study examining the first 30 days from presentation of acute pancreatitis in the UK

Abstract Background Acute pancreatitis is a common, yet complex, emergency surgical presentation. Multiple guidelines exist and management can vary significantly. The aim of this first UK, multicentre, prospective cohort study was to assess the variation in management of acute pancreatitis to guide resource planning and optimize treatment. Methods All patients aged greater than or equal to 18 years presenting with acute pancreatitis, as per the Atlanta criteria, from March to April 2021 were eligible for inclusion and followed up for 30 days. Anonymized data were uploaded to a secure electronic database in line with local governance approvals. Results A total of 113 hospitals contributed data on 2580 patients, with an equal sex distribution and a mean age of 57 years. The aetiology was gallstones in 50.6 per cent, with idiopathic the next most common (22.4 per cent). In addition to the 7.6 per cent with a diagnosis of chronic pancreatitis, 20.1 per cent of patients had a previous episode of acute pancreatitis. One in 20 patients were classed as having severe pancreatitis, as per the Atlanta criteria. The overall mortality rate was 2.3 per cent at 30 days, but rose to one in three in the severe group. Predictors of death included male sex, increased age, and frailty; previous acute pancreatitis and gallstones as aetiologies were protective. Smoking status and body mass index did not affect death. Conclusion Most patients presenting with acute pancreatitis have a mild, self-limiting disease. Rates of patients with idiopathic pancreatitis are high. Recurrent attacks of pancreatitis are common, but are likely to have reduced risk of death on subsequent admissions. </jats:sec

Role and regulation of the metalloproteinase ADAM8 in liver inflammation and hepatocellular carcinoma

The liver is the main site for the metabolism of lipids, proteins, and carbohydrates and is constantly exposed to the gut-derived metabolites such as lipopolysaccharides (LPS) and toxins which could normally trigger an immune response in the liver resulting in liver inflammation. LPS is also involved in the development and progression of chronic liver injury which includes viral hepatitis, alcoholic liver disease, and non-alcoholic fatty liver disease (NAFLD). NAFLD includes a spectrum of diseases ranging from simple steatosis to a progressive form of the disease that is non-alcoholic steatohepatitis which can further progress to cirrhosis and hepatocellular carcinoma (HCC). During the past decades, ADAM family members have been discussed vastly for their role in the development of inflammation and cancer. ADAM8 is one of the important members of the ADAM family that is strongly associated with inflammation and metastasis, not only via its catalytic activity but also via interaction with other cell surface proteins. The present study aimed to establish and explore the relationship of ADAM8 with liver inflammation and liver carcinoma. In inflammatory mouse models such as NAFLD, LPS, bile duct ligation (BDL) and after partial hepatectomy the mRNA expression of ADAM8 was upregulated compared to healthy controls. The enhanced mRNA expression of ADAM8 in the tested mouse models was associated with elevated expression of TNFα and IL-6. In parallel, the regulation of ADAM8 expression was studied in-vitro using different cultured liver cell types. ADAM8 expression was highly upregulated on mRNA and protein levels in human and murine hepatocyte cell lines, endothelial cell lines and liver stellate cells and also in primary murine hepatocytes, under NAFLD conditions. ADAM8 expression was then silenced in murine cells by using siRNA and in human cells using shRNA. The induction of released TNFα, IL-6, IL-8/KC, and CX3CL1 showed a positive association with ADAM8 expression in almost all cell types. Moreover, ADAM8 KD also reduced the mRNA expression of αSMA in liver stellate cells. The role of ADAM8 for the response to LPS was studied by using ADAM8 KD liver cells and ADAM8 knockout (KO) mice. Primary murine hepatocytes were also obtained from healthy control (WT) and ADAM8 KO mice and treated with LPS. LPS treatment increased the expression of ADAM8 in primary hepatocytes from control mice and in hepatocyte and endothelial cell lines. Along with this, the expression and release of TNFα and IL-6 were also increased and this response was reduced upon ADAM8 silencing. For in-vivo investigations, healthy controls and ADAM8 KO mice were either treated with saline or LPS to induce acute liver inflammation. LPS treatment elevated the mRNA expression of ADAM8, TNFα and IL-6 in healthy controls. ADAM8 KO appeared to reduce the expression of IL-6 only but this was not significant due to high variability among the animals. The release of TNFα and IL-6, and the liver enzyme levels were not much induced by LPS treatment. This may be explained by these circumstances that that this was a mild inflammation in the liver which could only elevate the mRNA expression of cytokines. The expression of ADAM8 is also highly upregulated in various cancers, which is correlated often with poor prognosis. In the present study, ADAM8 expression was found enhanced in HCC liver tissues. The comparison of ADAM8 expression in hepatocyte cell lines (hepatoma cell lines; HepG2 & Hepa1-6) and primary hepatocytes showed that ADAM8 is expressed at a much higher level in hepatoma cell lines. ADAM8 KD in hepatoma cell lines decreased cell proliferation, cell migration and cell invasion while ADAM8 overexpression increased all these cellular activities. Endothelial cells also showed decreased cell proliferation, migration and invasion upon ADAM8 KD. Additionally, tube formation capability of endothelial cells was reduced after ADAM8 KD. The apoptosis was highly induced in ADAM8 KD hepatoma cells and decreased upon ADAM8 overexpression. Furthermore, a positive relationship of ADAM8 was established with β1 integrin expression and activation of downstream signalling molecules including FAK, Src kinase, MAPK and Rho GTPase using hepatoma cell lines. These results indicate the critical role of ADAM8 in regulating metastasis via activating the β1-integrin-FAK-Rho axis in HCC cells. ADAM8 was also found essential for angiogenesis and targeting ADAM8 could not only control metastasis and proliferation but also angiogenesis in HCC

Expression of the Metalloproteinase ADAM8 Is Upregulated in Liver Inflammation Models and Enhances Cytokine Release In Vitro

Acute and chronic liver inflammation is driven by cytokine and chemokine release from various cell types in the liver. Here, we report that the induction of inflammatory mediators is associated with a yet undescribed upregulation of the metalloproteinase ADAM8 in different murine hepatitis models. We further show the importance of ADAM8 expression for the production of inflammatory mediators in cultured liver cells. As a model of acute inflammation, we investigated liver tissue from lipopolysaccharide- (LPS-) treated mice in which ADAM8 expression was markedly upregulated compared to control mice. In vitro, stimulation with LPS enhanced ADAM8 expression in murine and human endothelial and hepatoma cell lines as well as in primary murine hepatocytes. The enhanced ADAM8 expression was associated with an upregulation of TNF-α and IL-6 expression and release. Inhibition studies indicate that the cytokine response of hepatoma cells to LPS depends on the activity of ADAM8 and that signalling by TNF-α can contribute to these ADAM8-dependent effects. The role of ADAM8 was further confirmed with primary hepatocytes from ADAM8 knockout mice in which TNF-α and IL-6 induction and release were considerably attenuated. As a model of chronic liver injury, we studied liver tissue from mice undergoing high-fat diet-induced steatohepatitis and again observed upregulation of ADAM8 mRNA expression compared to healthy controls. In vitro, ADAM8 expression was upregulated in hepatoma, endothelial, and stellate cell lines by various mediators of steatohepatitis including fatty acid (linoleic-oleic acid), IL-1β, TNF-α, IFN-γ, and TGF-β. Upregulation of ADAM8 was associated with the induction and release of proinflammatory cytokines (TNF-α and IL-6) and chemokines (CX3CL1). Finally, knockdown of ADAM8 expression in all tested cell types attenuated the release of these mediators. Thus, ADAM8 is upregulated in acute and chronic liver inflammation and is able to promote inflammation by enhancing expression and release of inflammatory mediators