NLRP6 Inflammasome Modulates Disease Progression in a Chronic-Plus-Binge Mouse Model of Alcoholic Liver Disease

A considerable percentage of the population is affected by alcoholic liver disease (ALD). It is characterized by inflammatory signals from the liver and other organs, such as the intestine. The NLR family pyrin domain containing 6 (NLRP6) inflammasome complex is one of the most important inflammatory mediators. The aim of this study was to evaluate a novel mouse model for ALD characterized by 8-week chronic-plus-binge ethanol administration and to investigate the role of NLRP6 inflammasome for intestinal homeostasis and ALD progression using Nlrp6-/- mice. We showed that chronic-plus-binge ethanol administration triggers hepatic steatosis, injury, and neutrophil infiltration. Furthermore, we discovered significant changes of intestinal microbial communities, including increased relative abundances of bacteria within the phyla Bacteroidota and Campilobacterota, as well as reduced Firmicutes. In this ALD model, inhibiting NLRP6 signaling had no effect on liver steatosis or damage, but had a minor impact on intestinal homeostasis via affecting intestinal epithelium function and gut microbiota. Surprisingly, Nlrp6 loss resulted in significantly decreased hepatic immune cell infiltration. As a result, our novel mouse model encompasses several aspects of human ALD, such as intestinal dysbiosis. Interfering with NLRP6 inflammasome activity reduced hepatic immune cell recruitment, indicating a disease-aggravating role of NLRP6 during ALD.

On the Use of Heterogeneous Stock Mice to Map Transcriptomes Associated With Excessive Ethanol Consumption

We and many others have noted the advantages of using heterogeneous (HS) animals to map genes and gene networks associated with both behavioral and non-behavioral phenotypes. Importantly, genetically complex Mus musculus crosses provide substantially increased resolution to examine old and new relationships between gene expression and behavior. Here we report on data obtained from two HS populations: the HS/NPT derived from eight inbred laboratory mouse strains and the HS-CC derived from the eight collaborative cross inbred mouse strains that includes three wild-derived strains. Our work has focused on the genes and gene networks associated with risk for excessive ethanol consumption, individual variation in ethanol consumption and the consequences, including escalation, of long-term ethanol consumption. Background data on the development of HS mice is provided, including advantages for the detection of expression quantitative trait loci. Examples are also provided of using HS animals to probe the genes associated with ethanol preference and binge ethanol consumption.

Ethanol Disrupts Hormone-Induced Calcium Signaling in Liver

Receptor-coupled phospholipase C (PLC) is an important target for the actions of ethanol. In the ex vivo perfused rat liver, concentrations of ethanol >100 mM were required to induce a rise in cytosolic calcium (Ca2+) suggesting that these responses may only occur after binge ethanol consumption. Conversely, pharmacologically achievable concentrations of ethanol (≤30 mM) decreased the frequency and magnitude of hormone-stimulated cytosolic and nuclear Ca2+ oscillations and the parallel translocation of protein kinase C-β to the membrane. Ethanol also inhibited gap junction communication resulting in the loss of coordinated and spatially organized intercellular Ca2+ waves in hepatic lobules. Increasing the hormone concentration overcame the effects of ethanol on the frequency of Ca2+ oscillations and amplitude of the individual Ca2+ transients; however, the Ca2+ responses in the intact liver remained disorganized at the intercellular level, suggesting that gap junctions were still inhibited. Pretreating hepatocytes with an alcohol dehydrogenase inhibitor suppressed the effects of ethanol on hormone-induced Ca2+ increases, whereas inhibiting aldehyde dehydrogenase potentiated the inhibitory actions of ethanol, suggesting that acetaldehyde is the underlying mediator. Acute ethanol intoxication inhibited the rate of rise and the magnitude of hormone-stimulated production of inositol 1,4,5-trisphosphate (IP3), but had no effect on the size of Ca2+ spikes induced by photolysis of caged IP3. These findings suggest that ethanol inhibits PLC activity, but does not affect IP3 receptor function. We propose that by suppressing hormone-stimulated PLC activity, ethanol interferes with the dynamic modulation of [IP3] that is required to generate large, amplitude Ca2+ oscillations.