image: Infographic explaining how different types of inflammation are related to obesity and non-alcoholic fatty liver disease; Figure 7C, Biopsy samples from non-alcoholic fatty liver disease patients showing immune cell infiltration (arrows). view more
Credit: [Credit: Carla Schaffer / K.M. Hart et al. / AAAS]
Type Two Inflammation Might be Good for the Belly But Bad for the Liver An inflammatory response once thought to protect against obesity could exacerbate non-alcoholic fatty liver disease (NAFLD), which is why new findings suggest some targeted treatments for metabolic syndrome might need to be reevaluated. NAFLD is the most common type of progressive liver disease in developed countries and the second leading indication for liver transplantation. What's more, direct medical costs associated with NAFLD total as much as $103 billion every year in the United States, and no drugs are approved to treat the 64 million people in the nation living with the condition. Because obesity, NAFLD, and inflammation are closely linked, ongoing efforts have attempted to develop interventions designed to modulate affected individuals' immune responses. Multiple types of inflammation exist, and type 1 has been linked to insulin resistance in obesity, while type 2 is thought to maintain healthy metabolic signaling in fatty tissues (in addition to protecting the body against parasitic worms). Here, Kevin Hart and colleagues made an unexpected discovery: that genetic predisposition towards type 1 inflammation protected mice against liver fibrosis from NAFLD following consumption of a high-fat diet. Yet, surprisingly, Hart et al. found evidence for type 2 inflammation in biopsy samples from 56 human patients with severe liver fibrosis from NAFLD. An anti-inflammatory therapy called TGF- β blockade reduced markers for NAFLD-associated fibrosis in mice fed a high fat diet, but increased type 2 inflammation in the animals' livers. The authors say that signs of type 2 inflammation in the liver could be used as clinical indicators to predict NAFLD progression.
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Journal
Science Translational Medicine