Adipose tissue (AT) has a modulating role in obesity-induced metabolic complications like type 2 diabetes mellitus (T2DM) via the production of so-called adipokines such as leptin, adiponectin, and resistin. The adipokines are believed to influence other tissues and to affect insulin resistance, liver function, and to increase the risk of T2DM. In this study, we examined the impact of intervention with the short-chain fatty acid butyrate following a high-fat diet (HFD) on AT function and other metabolic risk factors associated with obesity and T2DM in mice during mid- and late life. In both mid- and late adulthood, butyrate reduced HFD-induced adipocyte hypertrophy and elevations in leptin levels, which were associated with body weight, and cholesterol and triglyceride levels. HFD feeding stimulated macrophage accumulation primarily in epididymal AT in both mid- and late life adult mice, which correlated with liver inflammation in late adulthood. In late-adult mice, butyrate diminished increased insulin levels, which were related to adipocyte size and macrophage content in epididymal AT. These results suggest that dietary butyrate supplementation is able to counteract HFD-induced detrimental changes in AT function and metabolic outcomes in late life. These changes underlie the obesity-induced elevated risk of T2DM, and therefore it is suggested that butyrate has potential to attenuate risk factors associated with obesity and T2DM.

The development of non-alcoholic steatohepatitis (NASH) has been associated with alterations in gut microbiota composition and reduced gut barrier function. Akkermansia muciniphila is a gut microbe that is thought to have health-promoting properties, including the ability to improve gut barrier function and host metabolism, both when administered live and after heat-inactivation. We questioned whether heat-inactivated A. muciniphila may reduce NASH development. Ldlr−/−.Leiden mice, a translational, diet-induced model for NASH, were fed a NASH-inducing high-fat diet (HFD) supplemented with heat-inactivated A. muciniphila. After 28 weeks, effects of the treatment on obesity and associated metabolic dysfunction in the gut (microbiota composition and permeability), adipose tissue, and liver were studied relative to an untreated HFD control. Treatment with heat-inactivated A. muciniphila did not affect body weight or adiposity and had no effect on plasma lipids, blood glucose, or plasma insulin. Heat-inactivated A. muciniphila had some minor effects on mucosal microbiota composition in ileum and colon and improved gut barrier function, as assessed by an in vivo functional gut permeability test. Epidydimal white adipose tissue (WAT) hypertrophy and inflammation were not affected, but heat-inactivated A. muciniphila did reduce hypertrophy in the mesenteric WAT which is in close proximity to the intestine. Heat-inactivated A. muciniphila did not affect the development of NASH or associated fibrosis in the liver and did not affect circulating bile acids or markers of liver fibrosis, but did reduce PRO-C4, a type IV collagen synthesis marker, which may be associated with gut integrity. In conclusion, despite beneficial effects in the gut and mesenteric adipose tissue, heat-inactivated A. muciniphila did not affect the development of NASH and fibrosis in a chronic disease setting that mimics clinically relevant disease stages.

Blood-based biomarkers allow monitoring of an individual’s health status and provide insights into metabolic and inflammatory processes in conditions like obesity, cardiovascular, and liver diseases. However, selecting suitable biomarkers and optimizing analytical assays presents challenges, is time-consuming and laborious. Moreover, knowledge of potential sex differences remains incomplete as research is often carried out in men. This study aims at enabling researchers to make informed choices on the type of biomarkers, analytical assays, and dilutions being used. More specifically, we analyzed plasma concentrations of >90 biomarkers using commonly available ELISA or electrochemiluminescence-based multiplex methods, comparing normal weight (BMI < 25; n = 40) with obese (BMI > 30; n = 40) adult blood donors of comparable age. To help choose optimal biomarker sets, we grouped frequently employed biomarkers into biological categories (e.g., adipokines, acute-phase proteins, complement factors, cytokines, myokines, iron metabolism, vascular inflammation), first comparing normal-weight with obese persons, and thereafter exploratively comparing women and men within each BMI group. Many biomarkers linked to chronic inflammation and dysmetabolism were elevated in persons with obesity, including several adipokines, interleukins, chemokines, acute-phase proteins, complement factors, and oxidized LDL. Further exploration suggests sex disparities in biomarker levels within both normal-weight and obese groups. This comprehensive dataset of biomarkers across diverse biological domains constitutes a reference resource that may provide valuable guidance for researchers in selecting appropriate biomarkers and analytical assays for own studies. Moreover, the dataset highlights the importance of taking possible sex differences into account.