Endogenous metabolism in endothelial and immune cells generates most of the tissue vitamin B3 (nicotinamide).

In mammals, nicotinamide (NAM) is the primary NAD precursor available in circulation, a signaling molecule, and a precursor for methyl-nicotinamide (M-NAM) synthesis. However, our knowledge about how the body regulates tissue NAM levels is still limited. Here we demonstrate that dietary vitamin B3 partially regulates plasma NAM and NAM-derived metabolites, but not their tissue levels. We found that NAD de novo synthesis from tryptophan contributes to plasma and tissue NAM, likely by providing substrates for NAD-degrading enzymes. We also demonstrate that tissue NAM is mainly generated by endogenous metabolism and that the NADase CD38 is the main enzyme that produces tissue NAM. Tissue-specific CD38-floxed mice revealed that CD38 activity on endothelial and immune cells is the major contributor to tissue steady-state levels of NAM in tissues like spleen and heart. Our findings uncover the presence of different pools of NAM in the body and a central role for CD38 in regulating tissue NAM levels.

The CD38 glycohydrolase and the NAD sink: implications for pathological conditions.

Nicotinamide adenine dinucleotide (NAD) acts as a cofactor in several oxidation-reduction (redox) reactions and is a substrate for a number of nonredox enzymes. NAD is fundamental to a variety of cellular processes including energy metabolism, cell signaling, and epigenetics. NAD homeostasis appears to be of paramount importance to health span and longevity, and its dysregulation is associated with multiple diseases. NAD metabolism is dynamic and maintained by synthesis and degradation. The enzyme CD38, one of the main NAD-consuming enzymes, is a key component of NAD homeostasis. The majority of CD38 is localized in the plasma membrane with its catalytic domain facing the extracellular environment, likely for the purpose of controlling systemic levels of NAD. Several cell types express CD38, but its expression predominates on endothelial cells and immune cells capable of infiltrating organs and tissues. Here we review potential roles of CD38 in health and disease and postulate ways in which CD38 dysregulation causes changes in NAD homeostasis and contributes to the pathophysiology of multiple conditions. Indeed, in animal models the development of infectious diseases, autoimmune disorders, fibrosis, metabolic diseases, and age-associated diseases including cancer, heart disease, and neurodegeneration are associated with altered CD38 enzymatic activity. Many of these conditions are modified in CD38-deficient mice or by blocking CD38 NADase activity. In diseases in which CD38 appears to play a role, CD38-dependent NAD decline is often a common denominator of pathophysiology. Thus, understanding dysregulation of NAD homeostasis by CD38 may open new avenues for the treatment of human diseases.

CD38 ecto-enzyme in immune cells is induced during aging and regulates NAD+ and NMN levels.

Decreased 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 an increase in CD38 in white adipose tissue (WAT) and the 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 decreases 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+.

Erratum: Correction Notice: Two Different Methods of Quantification of Oxidized Nicotinamide Adenine Dinucleotide (NAD+) and Reduced Nicotinamide Adenine Dinucleotide (NADH) Intracellular Levels: Enzymatic Coupled Cycling Assay and Ultra-performance Liquid Chromatography (UPLC)-Mass Spectrometry.

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Erratum: Correction Notice: Measuring CD38 Hydrolase and Cyclase Activities: 1,N6-Ethenonicotinamide Adenine Dinucleotide (ε-NAD) and Nicotinamide Guanine Dinucleotide (NGD) Fluorescence-based Methods.

[This corrects the article .].

Measuring CD38 Hydrolase and Cyclase Activities: 1,N6-Ethenonicotinamide Adenine Dinucleotide (ε-NAD) and Nicotinamide Guanine Dinucleotide (NGD) Fluorescence-based Methods.

CD38 is a multifunctional enzyme involved in calcium signaling and Nicotinamide Adenine Dinucleotide (NAD+) metabolism. Through its major activity, the hydrolysis of NAD+, CD38 helps maintain the appropriate levels of this molecule for all NAD+-dependent metabolic processes to occur. Due to current advances and studies relating NAD+ decline and the development of multiple age-related conditions and diseases, CD38 gained importance in both basic science and clinical settings. The discovery and development of strategies to modulate its function and, possibly, treat diseases and improve health span put CD38 under the spotlights. Therefore, a consistent and reliable method to measure its activity and explore its use in medicine is required. We describe here the methods how our group measures both the hydrolase and cyclase activity of CD38, utilizing a fluorescence-based enzymatic assay performed in a plate reader using 1,N6-Ethenonicotinamide Adenine Dinucleotide (ε-NAD) and Nicotinamide Guanine Dinucleotide (NGD) as substrates, respectively.

Two Different Methods of Quantification of Oxidized Nicotinamide Adenine Dinucleotide (NAD+) and Reduced Nicotinamide Adenine Dinucleotide (NADH) Intracellular Levels: Enzymatic Coupled Cycling Assay and Ultra-performance Liquid Chromatography (UPLC)-Mass Spectrometry.

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.

A Potent and Specific CD38 Inhibitor Ameliorates Age-Related Metabolic Dysfunction by Reversing Tissue NAD+ Decline.

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.

Superior mesenteric artery stenting using embolic protection device for treatment of acute or chronic mesenteric ischemia.

OBJECTIVE: The objective of the study was to report the feasibility and results of superior mesenteric artery (SMA) stenting using embolic protection devices (EPDs) to treat acute mesenteric ischemia (AMI) and chronic mesenteric ischemia (CMI). METHODS: A retrospective review was conducted of consecutive patients who underwent SMA stenting with EPDs from 2007 to 2016. EPDs were used selectively in patients with occlusions, severe calcification, or acute thrombus. A two-wire technique with SpiderFX 0.014-inch filter wire (Medtronic, Minneapolis, Minn) combined with a 0.018-inch wire was used to provide support and to facilitate stenting and EPD retrieval. Presence of macroscopic debris in the EPD was recorded and graded as minor (minimal debris) or major (large thrombus or plaque). End points were technical success, presence of EPD debris, embolization, early morbidity, and mortality. RESULTS: SMA stenting was performed in 179 patients, of whom 65 (36%) had EPDs. The mean age was 73 ± 11 years, and 49 were female (75%). Clinical presentation was CMI in 48 patients (74%) and AMI or acute-on-CMI in 17 (26%). Indications for EPD were severe calcification in 22 patients (34%), acute thrombus in 18 (28%), and total occlusion in 16 (25%). Bare-metal stents were used in 33 patients, covered stents in 26, and both types in 6. Adjunctive therapy included thrombolysis in seven patients, thrombectomy in four, and atherectomy in three. Technical success was 100%. There were no instances of filter retention or arterial trauma due to filter manipulation. Distal embolization was noted in four patients (6%), of whom two had AMI. All large emboli were retrieved using catheter aspiration devices, but one small distal embolus was left untreated with no clinical consequences. Two patients had vessel spasm treated by nitroglycerin. Macroscopic debris was noted in 43 patients (66%) and was major in 21 (49%) or minor in 22 (51%). Of the patients with AMI, five (29%) required exploratory laparotomy and four (23%) had bowel resection. Eight additional patients (12%) had early complications (five CMI, three AMI), including cardiac complications, brachial hematoma, acute cholecystitis, and acute respiratory distress syndrome in two patients each. There were no deaths among CMI patients and two early deaths (12%) among those who had AMI. CONCLUSIONS: Use of EPDs during SMA stenting is safe and feasible with a two-wire technique. Large macroscopic debris was noted in one-third of the patients when the filter was applied selectively in patients with acute symptoms, occlusions, or severely calcified lesions. Despite the use of EPD, distal embolization occurred in 6% of patients and was successfully treated using catheter aspiration devices.

Outcomes of reoperative open or endovascular interventions to treat patients with failing open mesenteric reconstructions for mesenteric ischemia.

OBJECTIVE: Outcomes of reinterventions for failing mesenteric open reconstructions (ORs) have not been described. Mesenteric reoperative ORs (R-ORs) are challenging because of excessive scar and more advanced mesenteric disease. The purpose of this study was to evaluate outcomes of R-ORs and endovascular revascularization (ER) in patients with stenosis or occlusion of mesenteric grafts. METHODS: We reviewed 701 patients treated for chronic mesenteric ischemia (CMI) in two academic centers from 1991 to 2013. Clinical data and outcomes of patients treated for failing ORs with R-ORs or ERs were included in the analysis. A 1:2 case-control matching was used to analyze outcomes of R-ORs compared with patients who underwent their first-time ORs for CMI. End points were early and late mortality, morbidity, patency rates, and freedom from symptom recurrence and reintervention. RESULTS: There were 47 patients (five men, 42 women; mean age, 58 ± 13 years) with failing ORs who were treated by R-ORs. Clinical presentation was CMI in 38 patients (81%) or acute mesenteric ischemia (AMI) in nine (19%). Reinterventions included R-ORs in 28 patients (19 CMI and nine AMI) and ERs in 19, all for CMI. Early mortality was 22% in patients treated by R-ORs for AMI. There were no early deaths among patients treated for CMI with R-OR or ER. Early morbidity was 78% for R-ORs in patients treated for AMI. Morbidity was significantly higher for R-ORs than for ERs in patients with CMI (63% vs 16%; P < .05). Mean follow-up was 50 ± 60 months. Patient survival at 5 years was 60% ± 8% for the entire cohort. Primary and secondary patency at 1 year were 61% ± 10% and 92% ± 8% for R-ORs (P = .34) and 77% ± 10% and 100% for ERs (P = .41). Freedom from symptom recurrence and reinterventions at 1 year was 88% ± 6% and 87% ± 7% for R-ORs and 83% ± 8% and 71% ± 10% for ERs. Case case-control (1:2) matching showed R-OR was associated with similar early mortality and morbidity and also similar freedom from recurrence and reintervention but with lower primary patency rates at 1 year compared with first time ORs (66% ± 11% and 94% ± 5%; P < .05). CONCLUSIONS: R-OR or ER interventions for failing mesenteric ORs carry similar mortality, recurrence, and reintervention rates. Early morbidity is lower with ER compared with R-OR. R-ORs are associated with similar morbidity and mortality and lower primary patency compared with first-time OR for CMI.

Technique of implantation and bail-out maneuvers for endovascular fenestrated repair of juxtarenal aortic aneurysms.

Endovascular repair of complex aneurysms involving the visceral arteries has become a reality. Fenestrated endovascular aortic repair (FEVAR) has been used with increasing frequency to treat complex aortic aneurysms. The Zenith fenestrated stent-graft system (Cook Medical Inc, Brisbane, Australia) was approved for commercial use in the United States in April 2012, offering a custom-made design with up to 3 fenestrations to treat short-neck infrarenal and juxtarenal abdominal aortic aneurysms. Nevertheless, FEVAR is a complex procedure that demands accurate planning, advanced endovascular skills, and excellent perioperative patient care to achieve optimal outcomes. This article summarizes the basic concepts of device design, case planning, techniques of implantation, and some of the "bail-out" maneuvers that may be required during endovascular repair using the Zenith fenestrated stent-graft system.