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Recent studies have highlighted the relation between high-fat (HF) diets, the gut microbiota, and inflammation. However, the role of sulfidogenic bacteria in mediating these effects has been explored only recently. Therefore, we tested the hypothesis that an HF diet rich in saturated fat stimulates sulfidogenic bacteria and that these increases correlate with intestinal and systemic inflammatory responses. Forty C57BL/6Jmale mice were fed a low-fat (LF; 10%of energy) or an HF lard-based (60%of energy) diet for 6 or 20 wk. Mucosa samples were collected from the ileum, cecum, and colon and used for measuring 16S ribosomal RNA and functional genes of sulfidogenic bacteria. Matching intestinal samples and visceral and subcutaneous white adipose tissue (WAT) depots were used to measure mRNA abundance for inflammatory genes. Mice fed the HF diet had greater ( < P 0.05) abundance of 3 types of sulfidogenic bacteria, primarily in colonic mucosa, compared with LF-fed mice at week 20. Although HF feeding did not increase intestinal inflammation at week 6, ileal markers of macrophage infiltration and inflammation were upregulated (< 0.05) 1- to 6-fold at week 20. HF feeding impaired the localization of the tight junction protein zonula P occludens 1 at the apical area of the ileal epithelium at weeks 6 and 20.Mice fed the HF diet had 1- to 100-fold greater (< 0.05) P mRNA levels of markers of macrophage infiltration in visceral and subcutaneous WAT at week 20, but not at week 6, compared with LF-fed mice. These results provide evidence that chronic, but not acute, consumption of an HF lard-based diet may be linked with pathways of microbial metabolism that potentially contribute to chronic intestinal and systemic inflammation. Such linkage provides further support for reducing consumption of saturated fats. [ABSTRACT FROM AUTHOR]

We have demonstrated that trans-10, cis-12 conjugated linoleic acid (18:2t10,c12)-mediated delipidation of human adipocytes was dependent on increased intracellular calcium and activation of inflammatory signaling in human primary adipocytes. These data are consistent with the actions of diacylglycerol and inositol triphosphate derived from phospholipase C (PLC)-dependent cell signaling. To test the hypothesis that PLC was an upstream activator of these cellular responses to 18:2t10,c12, primary cultures of human adipocytes were pretreated with 1-[6-((17β-3-methoxyestra-1,3,5 (10)-trien-17-yl)amino)hexyl]-1H-pyrrole-2,5-dione (U73122), a universal PLC inhibitor, followed by 18:2t10,d 2 treatment. U73122 attenuated 18:2t10,c12-mediated insulin resistance within 48 h and suppression of the mRNA levels of peroxisome proliferator-activated receptor (PPAR)γ, insulin-stimulated glucose transporter-4, acetyl-CoA carboxylase-1, and stearoyl-CoA desaturase-1, and the protein levels of PPARγ within 18-24 h. U73122 inhibited 18:2t10,c12-mediated induction of the inflammatory-related genes calcium/calmodulin-dependent protein kinase-β, cyclooxygenase-2, monocyte chemoattractant protein-1, interleukin (IL)-6, and IL-8, secretion of IL-6 and IL-8, and the activation of extracellular signal-related kinase, c-Jun N-terminal kinase, and c-Jun within 18-24 h. Moreover, 13:2t10,c12 increased the mRNA levels of heat shock proteins within 6-24 h and intracellular calcium concentrations within 3 min, which were inhibited by U73122. Lastly, 18:2t10,c12 increased the abundance of PLCγ1 in the plasma membrane within 3 min. Taken together, these data suggest that PLC plays an important role in 18:2t10,c12-mediated activation of intracellular calcium accumulation, inflammatory signaling, delipidation, and insulin resistance in human primary adipocytes. [ABSTRACT FROM AUTHOR]