Aging is characterized by the development of metabolic dysfunction and frailty. Recent studies show that a reduction in nicotinamide adenine dinucleotide (NAD) is a key factor for the development of age-associated metabolic decline. We recently demonstrated that the NADase CD38 has a central role in age-related NAD decline. Here we show that a highly potent and specific thiazoloquin(az)olin(on)e CD38 inhibitor, 78c, reverses age-related NAD decline and improves several physiological and metabolic parameters of aging, including glucose tolerance, muscle function, exercise capacity, and cardiac function in mouse models of natural and accelerated aging. The physiological effects of 78c depend on tissue NAD levels and were reversed by inhibition of NAD synthesis. 78c increased NAD levels, resulting in activation of pro-longevity and health span-related factors, including sirtuins, AMPK, and PARPs. Furthermore, in animals treated with 78c we observed inhibition of pathways that negatively affect health span, such as mTOR-S6K and ERK, and attenuation of telomere-associated DNA damage, a marker of cellular aging. Together, our results detail a novel pharmacological strategy for prevention and/or reversal of age-related NAD decline and subsequent metabolic dysfunction.

Decreased nicotinamide adenine dinucleotide (NAD + ) levels have been shown to contribute to metabolic dysfunction during aging. NAD + decline can be partially prevented by knockout of the enzyme CD38. However, it is not known how CD38 is regulated during aging, and how its ecto-enzymatic activity impacts NAD + homeostasis. Here we show that increases in CD38 in white adipose tissue (WAT) and liver during aging is mediated by accumulation of CD38 + immune cells. Inflammation increases CD38 and decreases NAD + . In addition, senescent cells and their secreted signals promote accumulation of CD38 + cells in WAT, and ablation of senescent cells or their secretory phenotype decrease CD38, partially reversing NAD + decline. Finally, blocking the ecto-enzymatic activity of CD38 can increase NAD + through a nicotinamide mononucleotide (NMN)-dependent process. Our findings demonstrate that senescence-induced inflammation promotes accumulation of CD38 in immune cells that through its ecto-enzymatic activity decreases levels of NMN and NAD + .

Recent reports indicate that intracellular NAD levels decline in tissues during chronological aging, and that therapies aimed at increasing cellular NAD levels could have beneficial effects in many age-related diseases. The protein CD38 (cluster of differentiation 38) is a multifunctional enzyme that degrades NAD and modulates cellular NAD homeostasis. At the physiological level, CD38 has been implicated in the regulation of metabolism and in the pathogenesis of multiple conditions including aging, obesity, diabetes, heart disease, asthma, and inflammation. Interestingly, many of these functions are mediated by CD38 enzymatic activity. In addition, CD38 has also been identified as a cell-surface marker in hematologic cancers such as multiple myeloma, and a cytotoxic anti-CD38 antibody has been approved by the FDA for use in this disease. Although this is a remarkable development, killing CD38-positive tumor cells with cytotoxic anti-CD38 antibodies is only one of the potential pharmacological uses of targeting CD38. The present review discusses the biology of the CD38 enzyme and the current state of development of pharmacological tools aimed at CD38, and explores how these agents may represent a novel approach for treating human conditions including cancer, metabolic disease, and diseases of aging.

Summary The processes underlying synchronous multiple organ fibrosis in systemic sclerosis (SSc) remain poorly understood. Age-related pathologies are associated with organismal decline in nicotinamide adenine dinucleotide (NAD + ) that is due to dysregulation of NAD + homeostasis and involves the NADase CD38. We now show that CD38 is upregulated in patients with diffuse cutaneous SSc, and CD38 levels in the skin associate with molecular fibrosis signatures, as well as clinical fibrosis scores, while expression of key NAD + -synthesizing enzymes is unaltered. Boosting NAD + via genetic or pharmacological CD38 targeting or NAD + precursor supplementation protected mice from skin, lung, and peritoneal fibrosis. In mechanistic experiments, CD38 was found to reduce NAD + levels and sirtuin activity to augment cellular fibrotic responses, while inhibiting CD38 had the opposite effect. Thus, we identify CD38 upregulation and resulting disrupted NAD + homeostasis as a fundamental mechanism driving fibrosis in SSc, suggesting that CD38 might represent a novel therapeutic target.

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Carcinomas of the thyroid with Ewing family tumor element (CEFTEs) are small-cell thyroid tumors with epithelial differentiation that disclose p63 expression and EWSR1-FLI1 rearrangement, carry a favorable prognosis and may co-exist with papillary thyroid carcinoma (PTC) foci. Two histogenetic hypotheses have been advanced regarding the origin of CEFTEs: arising in PTCs or in solid cell nests (SCN). A total of 3 CEFTEs, 54 PTCs, and 10 SCNs were reviewed, and fluorescence in situ hybridization (FISH) technique was performed in all cases to search for the presence of EWSR1 rearrangements. The three CEFTEs disclosed the EWSR1-FLI1 rearrangement both in the small cell and in the PTC component. Out of the 54 PTC cases, 28 (51.9%) were positive, 20 (37.0%) were negative, and 6 (11.1%) were inconclusive for EWSR1 rearrangement; in two of the positive PTC cases, the EWSR1-FLI1 rearrangement was detected. Classic PTC disclosed more often the EWSR1 rearrangement than other PTC variants (p = 0.031). PTCs with EWSR1 rearrangement disclosed a lower percentage of nuclei with EWSR1 polysomy than those without EWSR1 rearrangement (p = 0.001). Out of the 10 SCNs, 7 (70.0%) were negative and 3 (30.0%) were inconclusive for the EWSR1 rearrangement. Monosomic nuclei were more frequent (mean of 44.3%) in SCNs than in PTCs (p < 0.001). The presence of the EWSR1-FLI1 rearrangement in PTC component of all studied CEFTEs and the existence of the EWSR1 rearrangement in some PTCs favor the origin of CEFTE from PTC. The high frequency of EWSR1 rearrangements in PTC may represent a new diagnostic marker of these tumors.

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Current studies on the age-related development of metabolic dysfunction and frailty are each day in more evidence. It is known, as aging progresses, nicotinamide adenine dinucleotide (NAD+) levels decrease in an expected physiological process. Recent studies have shown that a reduction in NAD+ is a key factor for the development of age-associated metabolic decline. Increased NAD+ levels in vivo results in activation of pro-longevity and health span-related factors. Also, it improves several physiological and metabolic parameters of aging, including muscle function, exercise capacity, glucose tolerance, and cardiac function in mouse models of natural and accelerated aging. Given the importance of monitoring cellular NAD+ and NADH levels, it is crucial to have a trustful method to do so. This protocol has the purpose of describing the NAD+ and NADH extraction from tissues and cells in an efficient and widely applicable assay as well as its graphic and quantitative analysis.