Regulation of Sirtuins in Sepsis-Induced Myocardial Damage: The Underlying Mechanisms for Cardioprotection

Sepsis is defined as "a life-threatening organ dysfunction caused by a dysregulated host response to infection". Although the treatment of sepsis has evolved rapidly in the last few years, the morbidity and mortality of sepsis in clinical treatment are still climbing. Sirtuins (SIRTs) are a highly conserved family of histone deacetylation involved in energy metabolism. There are many mechanisms of sepsis-induced myocardial damage, and more and more evidence show that SIRTs play a vital role in the occurrence and development of sepsis-induced myocardial damage, including the regulation of sepsis inflammation, oxidative stress and metabolic signals. This review describes our understanding of the molecular mechanisms and pathophysiology of sepsis-induced myocardial damage, with a focus on disrupted SIRTs regulation. In addition, this review also describes the research status of related therapeutic drugs, so as to provide reference for the treatment of sepsis.

NAD+ Protects against Hyperlipidemia-induced Kidney Injury in Apolipoprotein E-deficient Mice

Background: Hyperlipidemia is an independent risk factor for kidney injury. Several studies have shown that nicotinamide adenine dinucleotide (NAD+) is an important coenzyme involved in normal body metabolism. Therefore, this study aimed to investigate the possible protective effects of NAD+ against hyperlipidemia-induced kidney injury in apolipoprotein Edeficient (ApoE-/-) mice.

Methods: Twenty-five eight-week-old male ApoE-/- mice were randomly assigned into four groups: normal diet (ND), ND supplemented with NAD+ (ND+NAD+), high-fat diet (HFD), and HFD supplemented with NAD+ (HFD+NAD+). The mice were subjected to their respective diets for a duration of 16 weeks. Blood samples were obtained from the inferior vena cava, collected in serum tubes, and stored at -80°C until use. Kidney tissues was fixed in 10% formalin and then embedded in paraffin for histological evaluation. The remainder of the kidney tissues was snapfrozen in liquid nitrogen for Western blot analysis.

Results: Metabolic parameters (total cholesterol, triglycerides, low-density lipoprotein-cholesterol, creatinine, and blood urea nitrogen) were significantly higher in the HFD group compared to the other groups. Histological analysis revealed prominent pathological manifestations in the kidneys of the HFD group. The HFD+NAD+ group showed increased levels of oxidative stress markers (NRF2 and SOD2) and decreased levels of NOX4 compared to the HFD group. Furthermore, the HFD group exhibited higher levels of TGF-β, Smad3, Collagen I, Collagen III, Bax, and Bak compared to the other groups. NAD+ supplementation in the HFD+NAD+ group significantly increased the levels of SIRT3, HO-1, Bcl-2, and Bcl-xL compared to the HFD group. Additionally, NF-κB protein expression was higher in the HFD group than in the HFD+NAD+ group.

Conclusion: These findings demonstrated that NAD+ may hold potential as a clinical treatment for kidney injury caused by hyperlipidemia.

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Exercise reduces hyperlipidemia-induced cardiac damage in apolipoprotein E-deficient mice via its effects against inflammation and oxidative stress

Cardiovascular disease is a high incidence and mortality rate disease worldwide. Exercise training has become an established evidence-based treatment strategy that is beneficial for many cardiovascular diseases. This study aimed to investigate the effects of exercise on hyperlipidemia-induced cardiac damage in apolipoprotein E-deficient (ApoE^-/-) mice. Male ApoE^-/- mice were randomly divided into the following four groups: normal diet (ND), normal diet + exercise training (ND + E), high-fat diet (HFD), and high-fat diet + exercise training (HFD + E). Exercise training consisted of swimming for 40 min, 5 days/week for 12 weeks. After 12 weeks, histopathological alterations in cardiac tissue and the serum were measured. Furthermore, the NOX4, NRF2, SIRT1, TGF-β, HO-1, collagen III, Smad3, Bax, Bak, Bcl-2, Bcl-xl, IL-1β, IL-6, and IL-18 expression levels were evaluated using immunohistochemistry and western blotting; Results: the serum levels of SIRT1, GSH-Px, and SOD were lower in ApoE^-/- HFD mice compared with those in ApoE^-/- HFD + E mice. Significant pathological changes were observed in the ApoE^-/- HFD + E group compared with those in the ApoE^-/- HFD group. Increased levels of oxidative stress, fibrosis, and apoptosis, and decreased antioxidant expression in the ApoE^-/- HFD group compared with those in ApoE^-/- HFD + E mice. Exercise exerts protective effects against cardiac damage caused by hyperlipidemia.