Neutralization of Oxidized Phospholipids Ameliorates Non-alcoholic Steatohepatitis.

Oxidized phospholipids (OxPLs), which arise due to oxidative stress, are proinflammatory and proatherogenic, but their roles in non-alcoholic steatohepatitis (NASH) are unknown. Here, we show that OxPLs accumulate in human and mouse NASH. Using a transgenic mouse that expresses a functional single-chain variable fragment of E06, a natural antibody that neutralizes OxPLs, we demonstrate the causal role of OxPLs in NASH. Targeting OxPLs in hyperlipidemic Ldlr-/- mice improved multiple aspects of NASH, including steatosis, inflammation, fibrosis, hepatocyte death, and progression to hepatocellular carcinoma. Mechanistically, we found that OxPLs promote ROS accumulation to induce mitochondrial dysfunction in hepatocytes. Neutralizing OxPLs in AMLN-diet-fed Ldlr-/- mice reduced oxidative stress, improved hepatic and adipose-tissue mitochondrial function, and fatty-acid oxidation. These results suggest targeting OxPLs may be an effective therapeutic strategy for NASH

Bromodomain containing 9 (BRD9) regulates macrophage inflammatory responses by potentiating glucocorticoid receptor activity

In macrophages, homeostatic and immune signals induce distinct sets of transcriptional responses, defining cellular identity and functional states. The activity of lineage-specific and signal-induced transcription factors are regulated by chromatin accessibility and other epigenetic modulators. Glucocorticoids are potent antiinflammatory drugs; however, the mechanisms by which they selectively attenuate inflammatory genes are not yet understood. Acting through the glucocorticoid receptor (GR), glucocorticoids directly repress inflammatory responses at transcriptional and epigenetic levels in macrophages. A major unanswered question relates to the sequence of events that result in the formation of repressive regions. In this study, we identify bromodomain containing 9 (BRD9), a component of SWI/SNF chromatin remodeling complex, as a modulator of glucocorticoid responses in macrophages. Inhibition, degradation, or genetic depletion of BRD9 in bone marrow-derived macrophages significantly attenuated their responses to both liposaccharides and interferon inflammatory stimuli. Notably, BRD9-regulated genes extensively overlap with those regulated by the synthetic glucocorticoid dexamethasone. Pharmacologic inhibition of BRD9 potentiated the antiinflammatory responses of dexamethasone, while the genetic deletion of BRD9 in macrophages reduced high-fat diet-induced adipose inflammation. Mechanistically, BRD9 colocalized at a subset of GR genomic binding sites, and depletion of BRD9 enhanced GR occupancy primarily at inflammatory-related genes to potentiate GR-induced repression. Collectively, these findings establish BRD9 as a genomic antagonist of GR at inflammatory-related genes in macrophages, and reveal a potential for BRD9 inhibitors to increase the therapeutic efficacies of glucocorticoids

Neutralization of Oxidized Phospholipids Ameliorates Non-alcoholic Steatohepatitis

Oxidized phospholipids (OxPLs), which arise due to oxidative stress, are proinflammatory and proatherogenic, but their roles in non-alcoholic steatohepatitis (NASH) are unknown. Here, we show that OxPLs accumulate in human and mouse NASH. Using a transgenic mouse that expresses a functional single-chain variable fragment of E06, a natural antibody that neutralizes OxPLs, we demonstrate the causal role of OxPLs in NASH. Targeting OxPLs in hyperlipidemic Ldlr-/- mice improved multiple aspects of NASH, including steatosis, inflammation, fibrosis, hepatocyte death, and progression to hepatocellular carcinoma. Mechanistically, we found that OxPLs promote ROS accumulation to induce mitochondrial dysfunction in hepatocytes. Neutralizing OxPLs in AMLN-diet-fed Ldlr-/- mice reduced oxidative stress, improved hepatic and adipose-tissue mitochondrial function, and fatty-acid oxidation. These results suggest targeting OxPLs may be an effective therapeutic strategy for NASH