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As a marker of nocturnal hypoxemia, ODI rather than AHI might better explain the relationship between OSAS and FMD. Because body mass index and waist-to-hip ratio were identified as risk factors of high serum CRP in OSAS, obesity should be considered when predicting cardiovascular complications in OSAS.

Backgroundβ-aminoisobutyric acid (BAIBA) is produced in skeletal muscle during exercise and has beneficial effects on obesity-related metabolic disorders such as diabetes and non-alcoholic fatty liver disease. Thus, it is supposed to prevent high fat diet (HFD)-induced inflammation and insulin resistance in adipose tissue though anti-inflammatory effects in obesity. Previous reports have also demonstrated strong anti-inflammatory effects of BAIBA.MethodsWe used BAIBA treated fully differentiated 3T3T-L1 mouse adipocytes to investigate the effects of exogenous BAIBA on inflammation and insulin signaling in adipocytes. Insulin signaling-mediated proteins and inflammation markers were measured by Western blot analysis. Secretion of pro-inflammatory cytokines were measured by ELISA. Lipid accumulation in differentiated 3 T3-L1 cells was stained by Oil red-O. Statistical analysis was performed by ANOVA and student’s t test.ResultsBAIBA treatment suppressed adipogenesis assessed by adipogenic markers as well as lipid accumulation after full differentiation. We showed that BAIBA treatment stimulated AMP-activated protein kinase (AMPK) phosphorylation in a dose-dependent manner and lipopolysaccharide (LPS)-induced secretion of pro-inflammatory cytokines such as TNFα and MCP-1 was abrogated in BAIBA-treated 3 T3-L1 cells. Treatment of 3 T3-L1 cells with BAIBA reduced LPS-induced NFκB and IκB phosphorylation. Furthermore, BAIBA treatment ameliorated LPS-induced impairment of insulin signaling measured by IRS-1 and Akt phosphorylation and fatty acid oxidation. Suppression of AMPK by small interfering (si) RNA significantly restored these changes.ConclusionsWe demonstrated anti-inflammatory and anti-insulin resistance effects of BAIBA in differentiated 3 T3-L1 cells treated with LPS through AMPK-dependent signaling. These results provide evidence for the beneficial effects of BAIBA not only in liver and skeletal muscle cells but also in adipose tissue.Electronic supplementary materialThe online version of this article (10.1186/s12929-018-0431-7) contains supplementary material, which is available to authorized users.