Abstract: Lipodystrophies (LDs) are rare, complex disorders of the adipose tissue characterized by selective fat loss, altered adipokines profile and metabolic impairment. Sirtuins (SIRTs) are class III NAD+-dependent histone-deacetylases linked to fat metabolism. SIRT1 plays a critical role in metabolic health by deacetylating target proteins in tissues including liver, muscle and adipose tissue. Circulating SIRT1 levels have been found to be reduced in obesity while increased in anorexia nervosa and in patients experiencing weight loss. We evaluated circulating SIRT1 levels in relation to fat amount in 32 lipodystrophic patients affected by congenital or acquired LDs compared to non-LD subjects (24 with anorexia nervosa, 22 normal weight and 24 with obe-sity). SIRT1 serum levels were higher in LDs as compared with normal weight subjects (mean ± SEM: 4.17 ± 0.48 vs. 2.59 ± 0.20 ng/mL) or subjects with obesity (1.7 ± 0.39 ng/mL), whereas they were close to those measured in anorexia nervosa (3.44 ± 0.46 ng/mL). Our findings show that within the LD group there was no relationship between SIRT1 levels and the amount of body fat. The mechanisms responsible for secretion and regulation of SIRT1 in LD deserve further investi-gation.

Sirtuin 1 (SIRT1), a member of the NAD+-dependent deacetylases, plays a pivotal role in epigenetic regulation related to aging. As the most extensively studied sirtuin, SIRT1 influences numerous cellular processes including metabolism, DNA repair, and cell survival, by deacetylating both histone and non-histone proteins. Epigenetic modifications in SIRT1, such as DNA methylation and post-translational histone modifications, have profound effects on gene expression and chromatin structure, contributing to age-related pathologies including metabolic disorders, neurodegeneration, and cancer. SIRT1 also interacts with several transcription factors such as p53 and FOXO, regulating stress responses and cellular senescence. Its activity is modulated by factors such as NAD+ availability and specific activators like resveratrol, which have been explored for their potential to delay aging processes. The role of SIRT1 in promoting longevity is linked to its involvement in the regulation of key pathways like calorie restriction, a well-established method for extending lifespan in various species. Understanding SIRT1's epigenetic mechanisms offers promising therapeutic avenues for addressing aging and associated diseases.

Sirtuins, especially SIRT1, play a significant role in the regulation of inflammatory response, autophagy, and cell response to oxidative stress. Since their discovery, sirtuins have been regarded as anti-aging and longevity-promoting enzymes. Sirtuin-regulated processes seem to take part in most prevalent placental pathologies, such as preeclampsia. Furthermore, more and more research studies indicate that SIRT1 may prevent pre-eclampsia development, or at least alleviate its manifestations. Having taken this into consideration, we have made a review of recent studies on the role of sirtuins, especially SIRT1, in the regulation of processes determining normal or abnormal development and functioning of the placenta.

Serelaxin (RLX), the recombinant form of human Relaxin-2 hormone, protects the heart from the ischemia/reperfusion (I/R)-induced damage due to its anti-inflammatory, anti-apoptotic and antioxidant properties. RLX exerts its actions by binding to its specific RXFP1 receptor whereby it regulates multiple cellular transduction pathways. In this in vitro study we offer first evidence for the involvement of AMP kinase/Sirtuin1 (AMPK/SIRT1) pathway in the protection afforded by RLX against H/R-induced damage in H9c2 cells. Treatment of the H/R-exposed cells with RLX (17 nmol L−1) enhanced SIRT1 expression and activity. Inhibition of SIRT1 signaling with EX527 (10 µmol L-1) reduced the beneficial effect of the hormone on mitochondrial efficiency and cell apoptosis. Moreover, RLX upregulated AMPK pathway, as shown by the increase in the expression of phospho-AMPK active protein. Finally, AMPK pathway inhibition by Compound C (10 and 20 μmol L−1) abrogated the increase in SIRT1 expression induced by RLX, thus suggesting the involvement of AMPK pathway in this effect of RLX. The results of this study strengthen the concept that RLX exerts its cardioprotective effects against H/R-induced injury by multiple pathways which also include AMPK/SIRT1.

Non-alcoholic steatohepatitis (NASH) is diagnosed by the occurrence of fat buildup, inflammation, and fibrotic changes within the liver. NASH has the capacity to proceed to the advancement of decompensated cirrhosis and carcinoma by inflammation and oxidative stress. Although Agrimonia pilosa has traditionally been used medicinal purposes, its effects on the liver remains incompletely elucidated. In this research, we assessed the therapeutic outcomes of Agrimonia pilosa extract (APE) on free fatty acid (FFA)-treated HepG2 cellular hepatic steatosis and in a choline-deficient, L-amino acid-defined, high-fat diet with 0.1% methionine (CDAHFD)-induced NASH mouse model. In FFA-treated cells, APE inhibited intracellular lipid accumulation, and regulated the mRNA and protein expressions of modulators of fatty acid (FA) synthesis as well as FA oxidation proteins, through down-regulation of the AMP-activated protein kinase/sirtuin 1 signaling pathway. In the CDAHFD-induced NASH mouse model, APE significantly enhanced liver histology and serum levels of liver damage. APE also significantly attenuated hepatic expression of mRNA and proteins related to FA synthesis, inflammation, and fibrosis. Furthermore, APE mitigated the expression levels of oxidative stress and endoplasmic reticulum stress. Overall, these discoveries indicate that Agrimonia pilosa has the potential to treat NASH by regulating hepatic lipid metabolism, alleviating inflammation, and mitigating oxidative stress.

Disrupted biological function, manifesting through the hallmarks of aging, poses as one of the largest threats to healthspan and risk of disease development, such as metabolic disorders, cardiovascular ailments, and neurodegeneration. In recent years, numerous geroprotectors, senolytics, and other nutraceuticals have emerged as potential disruptors of aging and may be viable interventions in the immediate state of human longevity science. In this review, we focus on the decrease of nicotinamide adenine dinucleotide (NAD+) with age and the supplementation of NAD+ precursors, such as nicotinamide mononucleotide (NMN) or nicotinamide riboside (NR), in combination with other geroprotective compounds to restore youthful NAD+ levels. Furthermore, these geroprotectors may enhance the efficacy of NMN supplementation while concurrently providing their own numerous health benefits. By analyzing the prevention of NAD+ degradation through inhibition of CD38 or supporting protective downstream agents of SIRT1, we provide a potential framework of the CD38/NAD+/SIRT1 axis through which geroprotectors may enhance the efficacy of NMN supplementation and reduce the risk of age-related diseases, thereby potentiating healthspan in humans.

Non-alcoholic fatty liver disease (NAFLD), a frequent complication of metabolic syndrome and visceral obesity, is characterized by marked accumulation of lipids in hepatocytes, accompanied by oxidant stress. In a substantial minority of cases, this progresses to steatohepatitis, which in turn can lead to life-threatening hepatic fibrosis and/or hepatocarcinogenesis. This essay analyzes the molecular biology underlying fat accumulation and oxidant stress in NAFLD, and identifies targets that can be addressed by nutraceutical or dietary measures. Nutraceuticals with potential for prevention or control of NAFLD – as suggested on theoretical grounds, and borne out by experience in rodent studies and/or clinical trials - include ferulic acid, melatonin, methylnicotinamide, tetrahydrocurcumin, nicotinamide riboside, carnosic acid, urolithin A, quercetin, high-dose biotin, citrulline, astaxanthin, long-chain omega-3 fatty acids, berberine, lipoic acid, silibinin, N-acetylcysteine, taurine, capsaicin, spermidine, spirulina, and carnitine. Some of these agents can also address the NLRP3 inflammasome activation and transforming growth factor-β signaling that play a role in driving the transition to steatohepatitis and fibrosis. In addition, soy isoflavones, via estrogen receptor-beta agonism, have anti-fibrotic potential, and supplemental glycine may blunt the contribution of Kupffer cells to the progression of NAFLD. Whole-food plant-based diets of modest protein content, owing to their impact on hormones such as fibroblast growth factor 21 and adiponectin, as well as on the obesity and metabolic syndrome underlying NAFLD, may also be protective in this syndrome. There is considerable potential for complex medical foods or nutraceutical supplementation regimens of rational design to aid prevention and control of NAFLD.