Protein and energy metabolism of young male Wistar rats fed conjugated linoleic acid as structured triacylglycerol

Conjugated linoleic acid (CLA) reduces intestinal fatty acid uptake and chylomicron formation in HFD-fed mice associated with the inhibition of DHHC7-mediated CD36 palmitoylation and the downstream ERK pathway

The anti-obesity effect of conjugated linoleic acid (CLA) has been well elucidated, but whether CLA affects fat deposition by regulating intestinal dietary fat absorption remains largely unknown. Thus, this study aimed to investigate the effects of CLA on intestinal fatty acid uptake and chylomicron formation and explore the possible underlying mechanisms. We found that CLA supplementation reduced the intestinal fat absorption in HFD (high fat diet)-fed mice accompanied by the decreased serum TG level, increased fecal lipids and decreased intestinal expression of ApoB48 and MTTP. Correspondingly, c9, t11-CLA, but not t10, c12-CLA induced the reduction of fatty acid uptake and TG content in PA (palmitic acid)-treated MODE-K cells. In the mechanism of fatty acid uptake, c9, t11-CLA inhibited the binding of CD36 with palmitoyltransferase DHHC7, thus leading to the decreases of CD36 palmitoylation level and localization on the cell membrane of the PA-treated MODE-K cells. In the mechanism of chylomicron formation, c9, t11-CLA inhibited the formation of the CD36/FYN/LYN complex and the activation of the ERK pathway in the PA-treated MODE-K cells. In in vivo verification, CLA supplementation reduced the DHHC7-mediated total and cell membrane CD36 palmitoylation and suppressed the formation of the CD36/FYN/LYN complex and the activation of the ERK pathway in the jejunum of HFD-fed mice. Altogether, these data showed that CLA reduced intestinal fatty acid uptake and chylomicron formation in HFD-fed mice associated with the inhibition of DHHC7-mediated CD36 palmitoylation and the downstream ERK pathway.

Conjugated linoleic acid (CLA) reduces HFD-induced obesity by enhancing BAT thermogenesis and iWAT browning via the CD36-AMPK pathway

The antiobesity effect of conjugated linoleic acid (CLA) has been reported. However, the underlying mechanisms have not been fully clarified. Thus, this study aimed to investigate the effects of CLA on thermogenesis of interscapular brown adipose tissue (iBAT) and browning of inguinal subcutaneous white adipose tissue (iWAT) and explore the possible signaling pathway. The in vivo results showed that CLA enhanced the O2 consumption and heat production in HFD (high-fat diet)-fed female mice by roughly 38%. Meanwhile, CLA increased the average iBAT temperature by 2°C at the room temperature and cold exposure, respectively. Correspondingly, CLA caused 1.6- and 2.4-fold increases in the expression of UCP1 (uncoupling protein 1) of BAT and iWAT, respectively, suggesting the activated iBAT thermogenesis and iWAT browning in HFD-fed female mice. Meanwhile, CLA could promote the formation of brown and beige adipocytes in differentiated stromal vascular cells (SVCs) isolated from iBAT and iWAT (the expressions of UCP1 were promoted by about twofold changes). In possible mechanisms, CLA stimulated the expression of CD36 and the activation of the AMPK pathway in mice iBAT and iWAT as well as the differentiated SVCs. However, inhibition of CD36 and AMPK (adenosine 5'-monophosphate-activated protein kinase) abolished the promotive effects of CLA on brown and beige adipocytes formation. Hence, we showed that CLA reduced HFD-induced obesity through enhancing iBAT thermogenesis and iWAT browning via the  CD36-AMPK pathway.

Meta-analysis of the efficacy and safety of structured triglyceride lipid emulsions in parenteral nutrition therapy in China

BACKGROUND & AIMS

We performed a meta-analysis of data from recent studies to evaluate the safety and efficacy of parenteral nutrition (PN) with structured triglyceride (STG) lipid emulsions compared to medium-chain triglyceride (MCT)/long-chain triglyceride (LCT) lipid emulsions in Chinese patients.

METHODS

PubMed, Embase, Cochrane Library, China National Knowledge Internet, Wanfang, and VIP were searched for randomized controlled trials comparing STGs with MCTs/LCTs published in English or Chinese between January 1987 and October 2017. Two independent investigators screened and selected studies according to prespecified selection criteria. Data were pooled and analysed using RevMan^® version 5.3.

RESULTS

Thirty-two studies comprising 1944 patients were included in the meta-analysis. Compared with MCT/LCT emulsions, STGs resulted in a shorter hospital length of stay (LOS) (weighted mean difference [WMD], -1.65 days; 95% confidence interval [CI]: -2.63, -0.67; P = 0.001) and lower adverse event rates (relative risk, 0.64; 95% CI: 0.48, 0.85; P = 0.002). STGs were associated with a significantly better cumulative nitrogen balance (WMD, 4.04 g/24 h; 95% CI: 3.10, 4.97; P < 0.0001) as well as higher concentrations of pre-albumin (WMD 35.20 mg/L; 95% CI: 26.59, 43.81; P < 0.0001) and albumin (WMD, 1.64 g/L; 95% CI: 1.17, 2.10; P < 0.0001) compared with MCTs/LCTs. In contrast, significantly lower concentrations of plasma triglycerides (WMD, -0.21 mmol/L; 95% CI: -0.30, -0.12; P < 0.0001), total cholesterol (WMD, -0.45 mmol/L; 95% CI: -0.60, -0.29; P < 0.0001), alanine aminotransferase (WMD, -7.68 IU/L; 95% CI: -9.68, -5.68; P < 0.0001) and aspartate aminotransferase (WMD, -10.27 IU/L; 95% CI: -16.05, -4.49; P = 0.0005) were observed in patients receiving STGs compared with MCT/LCTs. STGs were also associated with reduced inflammation and improved immunological function, as reflected by significantly lower C-reactive protein concentrations (WMD, -2.67 mg/L; 95% CI: -4.55, -0.79; P = 0.005) and increased concentrations of IgG (WMD, 2.11 g/L; 95% CI: 0.23, 3.99; P = 0.03), IgA (WMD, 0.21 g/L; 95% CI: 0.14, 0.28; P < 0.0001), CD3+ (WMD, 5.81%; 95% CI: 0.92, 10.70; P = 0.02), and CD4+/CD8+ (WMD, 0.12; 95% CI: 0.00, 0.24; P = 0.04) compared with MCT/LCTs.

CONCLUSIONS

Administration of STGs was shown to improve hepatic function, nutrition status, and immunological function and reduce inflammation, LOS, and adverse events compared with MCT/LCTs in Chinese patients receiving PN.

Nutrient Regulation: Conjugated Linoleic Acid's Inflammatory and Browning Properties in Adipose Tissue

Obesity is the most widespread nutritional disease in the United States. Developing effective and safe strategies to manage excess body weight is therefore of paramount importance. One potential strategy to reduce obesity is to consume conjugated linoleic acid (CLA) supplements containing isomers cis-9, trans-11 and trans-10, cis-12, or trans-10, cis-12 alone. Proposed antiobesity mechanisms of CLA include regulation of (a) adipogenesis, (b) lipid metabolism, (c) inflammation, (d) adipocyte apoptosis, (e) browning or beiging of adipose tissue, and (f) energy metabolism. However, causality of CLA-mediated responses to body fat loss, particularly the linkage between inflammation, thermogenesis, and energy metabolism, is unclear. This review examines whether CLA's antiobesity properties are due to inflammatory signaling and considers CLA's linkage with lipogenesis, lipolysis, thermogenesis, and browning of white and brown adipose tissue. We propose a series of questions and studies to interrogate the role of the sympathetic nervous system in mediating CLA's antiobesity properties.