Butyrate attenuates lipolysis in adipocytes co-cultured with macrophages through non-prostaglandin E2–mediated and prostaglandin E2–mediated pathways

Abstract

BackgroundInteractions between adipocytes and macrophages are associated with metabolic disorders. Production of pro-inflammatory mediators and the release of free fatty acids (FFAs) increase when these cells are co-cultured; butyrate significantly diminishes these effects by suppressing both the macrophage inflammatory and adipocyte lipolysis pathways. Butyrate is known to up-regulate the expression of prostaglandin E2 (PGE2). Therefore, we hypothesized that PGE2 is associated with the suppression of lipolysis by butyrate in co-culture.MethodsUsing contact or transwell co-culture methods with differentiated 3T3-L1 adipocytes and RAW264.7 macrophages, we investigated the effects of butyrate on the release of PGE2 into the medium and on lipolysis in adipocytes. To elucidate the underlying mechanism, we examined the effects of butyrate on cyclooxygenase-2 (COX2) and phospholipase A2 (PLA2) in co-cultured cells, and cyclic adenine monophosphate (cAMP) and protein kinase A type 1-α regulatory subunit (PRKAR1A) in co-cultured adipocytes. Silent interfering (si)RNA targeting of G-protein–coupled receptor (GPR)41 and 109A was employed to examine the effect on lipolysis in TNF-α–stimulated adipocytes.ResultsCo-culture increased PGE2 release into the medium, compared with cells cultured separately. Butyrate significantly increased PGE2 production. Co-culture elevated COX2 expression in macrophages and adipocytes, and butyrate further enhanced this effect. Co-culture enhanced cytosolic PLA2 activity in macrophages, which was further enhanced by butyrate. As for lipolysis, co-culture increased the release of FFAs and free glycerol into the medium, whereas butyrate (and to a lesser extent, PGE2) suppressed FFAs and free glycerol release. An inhibition study using a prostaglandin E receptor 3–selective antagonist suggested that approximately 40% of the suppressive effect of butyrate depends on the PGE2-mediated pathway, whereas 60% depends on a non-PGE2–mediated pathway. Co-culture increased cAMP and PRKAR1A levels in adipocytes, whereas butyrate restored the levels to those of the control. Similarly, in TNF-α–stimulated adipocytes, butyrate reduced FFAs and free glycerol release. siRNA inhibition of GPR41 and GPR109A suggested that the GPR109A-mediated pathway predominates, but the GPR41-mediated pathway also regulates the effect of butyrate on lipolysis in TNF-α–stimulated 3T3-L1 cells.ConclusionsButyrate attenuates lipolysis in adipocytes co-cultured with macrophages via non-PGE2–mediated and PGE2-mediated pathways.

Effects and mechanisms of caffeine to improve immunological and metabolic abnormalities in diet-induced obese rats

“…In fact, FFA loading is a common in vitro model to evaluate the effects of various agents on lipid accumulation (steatosis) in hepatocytes. It had been reported that coculture with macrophages increases the release of FFA from adipocytes into the CM (34). FAA incubation has been found to significantly increase IL-6 expression, which can increase lipogenesis in cultured hepatocytes (4).…”

Short-chain fatty acid, acylation and cardiovascular diseases

“…Similarly, oral administration of SCFAs (acetic acid, propionic acid, and butyric acid) decreases the concentration of triglyceride (TG) and could attenuate the fat deposition of pigs [76]. In addition, evidence in mouse and human also demonstrates that SCFAs modulate adipogenesis and attenuate lipolysis [77][78][79][80][81][82][83]. Therefore, SCFAs regulate energy metabolism via activating their receptors on adipocytes, which may produce adipokines such as leptin to participate in the development of CVDs.…”

Tributyrin Attenuates Metabolic and Inflammatory Changes Associated with Obesity through a GPR109A-Dependent Mechanism

“…A previous study suggested that NEFA concentrations in the circulation are more directly associated with liver injury than other parameters such as TAG deposition or TAG concentration in the circulation [60]. Other studies have also demonstrated a reduction in NEFA in mice treated with butyrate or Tb, associating this effect with inhibition of adipocyte lipolysis [39,61,62]. In our study, we found that, regardless of the genetics of mice (C57BL/6, Gpr43 −/− or Gpr109a −/− ), Tb decreased NEFA in serum, supporting the premise that this effect was not related to the activation of GPR43 or GPR109A, as we expected.…”