Accumulation of branched-chain amino acids reprograms glucose metabolism in CD8+ T cells with enhanced effector function and anti-tumor response.

Branched-chain amino acids (BCAAs) provide nutrient signals for cell survival and growth. How BCAAs affect CD8+ T cell functions remains unexplored. Herein, we report that accumulation of BCAAs in CD8+ T cells due to the impairment of BCAA degradation in 2C-type serine/threonine protein phosphatase (PP2Cm)-deficient mice leads to hyper-activity of CD8+ T cells and enhanced anti-tumor immunity. CD8+ T cells from PP2Cm-/- mice upregulate glucose transporter Glut1 expression in a FoxO1-dependent manner with more glucose uptake, as well as increased glycolysis and oxidative phosphorylation. Moreover, BCAA supplementation recapitulates CD8+ T cell hyper-functions and synergizes with anti-PD-1, in line with a better prognosis in NSCLC patients containing high BCAAs when receiving anti-PD-1 therapy. Our finding thus reveals that accumulation of BCAAs promotes effector function and anti-tumor immunity of CD8+ T cells through reprogramming glucose metabolism, making BCAAs alternative supplementary components to increase the clinical efficacy of anti-PD-1 immunotherapy against tumors.

Preoperative administration of branched-chain amino acids reduces postoperative insulin resistance in rats by reducing liver gluconeogenesis.

BACKGROUND: Postoperative insulin resistance (PIR) represents an important characteristic of metabolic response following surgical injury. Clinical outcomes are negatively correlated to postoperative insulin resistance and hyperglycemia, indicating a novel treatment for reducing postoperative insulin resistance is urgently needed. The current work aimed to assess the protective effects of branched-chain amino acids (BCAA) on glucose metabolism disorders induced surgically in a rat model, and to explore the underpinning mechanism. METHODS AND RESULTS: Rats were randomly assigned to 2 groups, including the control and BCAA groups. Rats were given a compulsory oral 3 mL load by gavage two hours before surgery. The results showed that BCAA remarkably reduced glycemia by suppressing liver gluconeogenesis via reduction of cAMP-response element-binding protein-regulated transcription coactivator 2 (CRTC2) and glucose-6-phosphatase (G6PC) gene and protein expression levels (all Ps < 0.05). CONCLUSIONS: This study revealed that BCAA lower blood glucose levels by reducing liver gluconeogenesis without significant elevation of plasma insulin levels. We anticipate that preoperative BCAA supplementation may be a means for preventing postoperative insulin resistance.

Selenium Supplementation Protects Against Lipopolysaccharide-Induced Heart Injury via Sting Pathway in Mice.

Sepsis-induced myocardial dysfunctions are associated with high morbidity and mortality. Selenium, an essential trace element, has been reported to exert anti-inflammation, anti-oxidative stress, and anti-apoptosis. However, the protective effects of selenium on LPS-induced heart injury are still poorly illustrated. Therefore, in the present study, we sought to explore the effects of selenium pretreatment on LPS-induced myocardial injury in mice. We firstly found that selenium pretreatment significantly improved markers of myocardial injury and alleviated LPS-induced myocardial dysfunctions. Moreover, selenium supplementation reduced pro-inflammatory cytokines expression, decreased oxidative stress, and inhibited myocardial apoptosis. In addition, selenium supplementation inactivated the Sting pathway. In conclusion, our study suggests that selenium exerts protective effects on LPS-induced myocardial injury, and the underlying molecular mechanism may be related to the inactivation of Sting pathway, implying a potential therapy for sepsis-induced myocardial dysfunctions.