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Background: Adipose tissue is one of the main sites of energy homeostasis that regulates whole body metabolism with the help of adipokines. Disruption in its proper functioning results in adipose tissue remodeling (primarily hypertrophy and hyperplasia) which directly influences the secretion of said adipokines. Obesity characterized as chronic low-grade inflammation of the adipose tissue is one such condition that has far reaching effects on whole body metabolism. Inflammation in turn results in immune cells infiltrating into the tissue and further promoting adipocyte dysfunction. Purpose: In our study we explored this adipose tissue-innate immunity axis by differentiating adipose tissue derived stem cells (ADSCs) into white and beige adipocytes. We further stimulated our cultures with lipopolysaccharide (LPS), flagellin, or meteorin-like, glial cell differentiation regulator (METRNL) to trigger an inflammatory response. We then evaluated Toll-like receptor (TLR) mRNA expression and secretion of interleukin (IL-6), interleukin-8 (IL-8), brain-derived neurotrophic factor (BDNF), and nerve growth factor (NGF) in these cultures. Results: We found that TLR2 is the highest expressed receptor in adipocytes. Further, LPS and METRNL are strong activators of TLR2 in white and beigeBMP7(-) adipocytes. TLR4 was not significantly expressed in any of our cultures despite LPS stimulation. TLR9 expression is upregulated in ADSCs upon LPS and METRNL stimulation. IL-6 and IL-8 secretion is increased upon LPS stimulation in white adipocytes. METRNL activates both IL-6 and IL-8 expression in adipocyte cultures. Lastly, BDNF and NGF is secreted by all adipocyte cultures with beigeBMP7(-) and beigeBMP7(+) secreting slightly higher amounts in comparison to white adipocytes. Conclusion: ADSCs and adipocytes alike are capable of expressing TLRs, but white adipocytes remain the highest expressing in both control and stimulated cultures. TLR2 is highly expressed in white and beige adipocytes whereas TLR4 showed no significant expression. LPS and METRNL trigger IL-6 and IL-8 secretion in adipocytes. Products of white adipocyte “browning” are capable of secreting higher amounts of BDNF and NGF in comparison to white adipocytes.

Background: Alkylresorcinols (ARs) are polyphenolic compounds with a wide spectrum of biological activities and potentially implicated in the regulation of host metabolism. The present study is aimed to establish whether ARs can be produced by human gut microbiota and to evaluate alterations in the content of ARs in stool samples of C57BL and db/db and LDLR (-/-) mice in dependence on diet specifications and olivetol (5-n-pentylresorcinol) supplementation in order to estimate a regulatory potential of ARs. Methods: The quantita-tive analysis of ARs levels in mice stool samples was performed using gas chromatography with mass spectrometric detection; fecal microbiota transplantation (FMT) from human donor to germ-free mice was performed to explore whether the intestinal microbiota could produce ARs molecules. Results: A significant increase in the amounts of individual mem-bers of ARs homologues in stool samples was revealed in 14 days after FMT. 5-n-Pentylresorcinol supplementation to a regular-chow diet influences the amounts of sev-eral ARs in stool of C57BL/6 and LDLR (-/-), but not db/db mice. Conclusions: For the first time, we have shown that several ARs can be produced by the intestinal microbiota. Taking into account, that AR concentrations in human serum are correlated with LPS levels and with microbiota diversity indexes in human stool samples, it can be assumed that ARs may serve as quorum-sensing molecules, influencing gut microbiota composition and host me-tabolism as well.