IFNγ-IL12 axis regulates intercellular crosstalk in metabolic dysfunction-associated steatotic liver disease.

Obesity is a major cause of metabolic dysfunction-associated steatohepatitis (MASH) and is characterized by inflammation and insulin resistance. Interferon-γ (IFNγ) is a pro-inflammatory cytokine elevated in obesity and modulating macrophage functions. Here, we show that male mice with loss of IFNγ signaling in myeloid cells (Lyz-IFNγR2-/-) are protected from diet-induced insulin resistance despite fatty liver. Obesity-mediated liver inflammation is also attenuated with reduced interleukin (IL)-12, a cytokine primarily released by macrophages, and IL-12 treatment in vivo causes insulin resistance by impairing hepatic insulin signaling. Following MASH diets, Lyz-IFNγR2-/- mice are rescued from developing liver fibrosis, which is associated with reduced fibroblast growth factor (FGF) 21 levels. These results indicate critical roles for IFNγ signaling in macrophages and their release of IL-12 in modulating obesity-mediated insulin resistance and fatty liver progression to MASH. In this work, we identify the IFNγ-IL12 axis in regulating intercellular crosstalk in the liver and as potential therapeutic targets to treat MASH.

Three Methods to Extract Membrane Glycerolipids: Comparing Sensitivity to Lipase Degradation and Yield.

Glycerolipids form the largest fraction of all membrane lipids and their composition changes quickly during plant development, the diurnal cycle, and in response to hormones and biotic or abiotic stress. A challenge to accurate glycerolipid measurement is that lipid-degrading enzymes tend to remain active during extraction, and special care must be taken to ensure their inactivation. Multiple extraction methods have arisen to cope with this challenge but only a few comparative studies are available in the literature. Here we compare three commonly used methods for lipase inactivation and lipid extraction from two different plant tissues. The first method employs formic acid in an organic solvent for inactivation followed by immediate separation of the organic phase, while the second uses the same acidic solvent, but expands the time of lipase inactivation and lipid extraction by incubation at low temperature. The third method includes a boiling step of the tissue in isopropanol for enzyme inactivation. The first method is the fastest for lab conditions with few samples, the second and third are convenient with large sample numbers, including field work. The first two methods are commonly followed by lipid derivatization and gas chromatography, while the third avoids acids and is thus preferable for lipidomics approaches. We directly compare the methods on both Arabidopsis thaliana and Sorghum bicolor leaf tissues and measure the relative abundances of glycerolipid species formed by lipase activity. We conclude that each method provides intact lipid extracts of similar quality, if performed according to the protocols described below.

Differential Effects of Whole Red Raspberry Polyphenols and Their Gut Metabolite Urolithin A on Neuroinflammation in BV-2 Microglia.

Whole red raspberry polyphenols (RRW), including ellagic acid, and their gut-derived metabolite, urolithin A (UroA), attenuate inflammation and confer health benefits. Although results from recent studies indicate that polyphenols and UroA also provide neuroprotective effects, these compounds differ in their bioavailability and may, therefore, have unique effects on limiting neuroinflammation. Accordingly, we aimed to compare the neuroprotective effects of RRW and UroA on BV-2 microglia under both 3 h and 12 and 24 h inflammatory conditions. In inflammation induced by lipopolysaccharide (LPS) and ATP stimulation after 3 h, RRW and UroA suppressed pro-inflammatory cytokine gene expression and regulated the JNK/c-Jun signaling pathway. UroA also reduced inducible nitric oxide synthase gene expression and promoted M2 microglial polarization. During inflammatory conditions induced by either 12 or 24 h stimulation with LPS, UroA-but not RRW-dampened pro-inflammatory cytokine gene expression and suppressed JNK/c-Jun signaling. Taken together, these results demonstrate that RRW and its gut-derived metabolite UroA differentially regulate neuroprotective responses in microglia during 3 h versus 12 and 24 h inflammatory conditions.