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

Clinical manifestations of anxiety and depression in sepsis-associated encephalopathy and multi-omics identification of cluster of differentiation 38 as an early biomarker

BACKGROUND

Sepsis-associated encephalopathy (SAE) is a common complication of sepsis, characterized by cognitive impairment, altered consciousness, and psychiatric symptoms, including anxiety and depression. These psychiatric symptoms often exacerbate the overall prognosis and quality of life of affected patients. However, the underlying metabolic and proteomic features associated with SAE-induced psychiatric symptoms remain poorly understood.

AIM

To investigate the clinical manifestations of anxiety and depression in patients with sepsis and SAE and to explore their associated metabolic and proteomic characteristics.

METHODS

A total of 88 patients were enrolled, comprising 30 healthy controls, 29 patients with sepsis, and 29 with SAE. Anxiety and depression symptoms were evaluated using the Hamilton anxiety rating scale (HAM-A) and Hamilton depression rating scale (HAM-D) in sepsis and SAE. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA), and quality of life was measured using the 36-Item Short Form Health Survey. Plasma samples were analyzed for metabolomic and proteomic profiling. Metabolic alterations were identified through liquid chromatography-mass spectrometry, while protein expression was assessed using Olink targeted proteomics.

RESULTS

Compared to the sepsis group, patients with SAE exhibited significantly higher levels of anxiety (HAM-A: 15.2 ± 4.0 vs 10.4 ± 3.0, P = 0.012) and depression (HAM-D: 16.0 ± 3.5 vs 9.1 ± 2.3, P = 0.003). Cognitive function, as measured by MoCA, was notably impaired in the SAE group (MoCA: 18.5 ± 4.0 vs 24.5 ± 3.2, P = 0.007). Quality of life scores, particularly in physical functioning, emotional well-being, and mental health, were significantly lower in patients with SAE. Metabolomic and proteomic analyses revealed substantial alterations in oxidative stress and nicotinamide adenine dinucleotide (NAD⁺) metabolism pathways, with cluster of differentiation (CD) 38 emerging as a potential biomarker associated with psychiatric symptoms in SAE. Further validation in an independent cohort confirmed the diagnostic relevance of CD38.

CONCLUSION

This study highlights the significant psychological burden of SAE, manifested as anxiety and depression. Multi-omics analysis identified distinct metabolic alterations, particularly in NAD⁺ metabolism, that may contribute to psychiatric symptom development and progression. Furthermore, CD38 was identified as a promising biomarker for the early detection of SAE, providing potential avenues for early intervention and therapeutic targeting.

NAD+ glycohydrolases-CD38 as a therapeutic target in aging: physiological roles, molecular mechanisms, and future opportunities in anti-aging research

As individuals age, tissue homeostasis and functionality gradually deteriorate, leading to the occurrence and advancement of age-related illnesses. Nicotinamide adenine dinucleotide (NAD+) is essential for metabolism and cellular energy generation. The significance of maintaining adequate the levels of NAD+ within biological systems to ameliorate age-related tissue degeneration and prevent age-related illnesses in senescent animals is now widely recognized, emphasizing the importance of increasing NAD+ levels. Cluster of differentiation 38 (CD38), a multifunctional enzyme, plays a significant role in maintaining the cellular equilibrium of NAD+ through the consumption of NAD+. Recent research has shown a correlation between aging and upregulation of CD38 expression, potentially resulting in a reduction in NAD+ with increasing age. In contrast, the lack of CD38 has been shown to have a beneficial effect on slowing the aging process. Consequently, CD38 has been increasingly identified as a potential therapeutic target for interventions aimed at combatting aging. This study investigated the physiological roles of CD38, its ramifications in the aging process, possible molecular mechanisms associated with its involvement in aging-related diseases, and possible therapeutic applications of small-molecule inhibitors targeting CD38 in the context of aging. In this review, we provide a comprehensive analysis of the potential applications and future opportunities of CD38 in anti-aging research.

Age- and diet-instructed metabolic rewiring of the tumor-immune microenvironment

The tumor-immune microenvironment (TIME) plays a critical role in tumor development and metastasis, as it influences the evolution of tumor cells and fosters an immunosuppressive state by intervening the metabolic reprogramming of infiltrating immune cells. Aging and diet significantly impact the metabolic reprogramming of the TIME, contributing to cancer progression and immune evasion. With aging, immune cell function declines, leading to a proinflammatory state and metabolic alterations such as increased oxidative stress and mitochondrial dysfunction, which compromise antitumor immunity. Similarly, dietary factors, particularly high-fat and high-sugar diets, promote metabolic shifts, creating a permissive TIME by fostering tumor-supportive immune cell phenotypes while impairing the tumoricidal activity of immune cells. In contrast, dietary restrictions have been shown to restore immune function by modulating metabolism and enhancing antitumor immune responses. Here, we discuss the intricate interplay between aging, diet, and metabolic reprogramming in shaping the TIME, with a particular focus on T cells, and highlight therapeutic strategies targeting these pathways to empower antitumor immunity.

Aging at the Crossroads of Organ Interactions: Implications for the Heart

Aging processes underlie common chronic cardiometabolic diseases such as heart failure and diabetes. Cross-organ/tissue interactions can accelerate aging through cellular senescence, tissue wasting, accelerated atherosclerosis, increased vascular stiffness, and reduction in blood flow, leading to organ remodeling and premature failure. This interorgan/tissue crosstalk can accelerate aging-related dysfunction through inflammation, senescence-associated secretome, and metabolic and mitochondrial changes resulting in increased oxidative stress, microvascular dysfunction, cellular reprogramming, and tissue fibrosis. This may also underscore the rising incidence and co-occurrence of multiorgan dysfunction in cardiometabolic aging in the population. Examples include interactions between the heart and the lungs, kidneys, liver, muscles, and brain, among others. However, this phenomenon can also present new translational opportunities for identifying diagnostic biomarkers to define early risks of multiorgan dysfunction, gain mechanistic insights, and help to design precision-directed therapeutic interventions. Indeed, this opens new opportunities for therapeutic development in targeting multiple organs simultaneously to disrupt the crosstalk-driven process of mutual disease acceleration. New therapeutic targets could provide synergistic benefits across multiple organ systems in the same at-risk patient. Ultimately, these approaches may together slow the aging process itself throughout the body. In the future, with patient-centered multisystem coordinated approaches, we can initiate a new paradigm of multiorgan early risk prediction and tailored intervention. With emerging tools including artificial intelligence-assisted risk profiling and novel preventive strategies (eg, RNA-based therapeutics), we may be able to mitigate multiorgan cardiometabolic dysfunction much earlier and, perhaps, even slow the aging process itself.

Age-associated nicotinamide adenine dinucleotide decline drives CAR-T cell failure

Chimeric antigen receptor (CAR) T cell therapy is one of the most promising cancer treatments. However, different hurdles are limiting its application and efficacy. In this context, how aging influences CAR-T cell outcomes is largely unknown. Here we show that CAR-T cells generated from aged female mice present a mitochondrial dysfunction derived from nicotinamide adenine dinucleotide (NAD) depletion that leads to poor stem-like properties and limited functionality in vivo. Moreover, human data analysis revealed that both age and NAD metabolism determine the responsiveness to CAR-T cell therapy. Targeting NAD pathways, we were able to recover the mitochondrial fitness and functionality of CAR-T cells derived from older adults. Altogether, our study demonstrates that aging is a limiting factor to successful CAR-T cell responses. Repairing metabolic and functional obstacles derived from age, such as NAD decline, is a promising strategy to improve current and future CAR-T cell therapies.

The Role of NAD+ Metabolism in Cardiovascular Diseases: Mechanisms and Prospects

Nicotinamide adenine dinucleotide (NAD+) is a promising anti-aging molecule that plays a role in cellular energy metabolism and maintains redox homeostasis. Additionally, NAD+ is involved in regulating deacetylases, DNA repair enzymes, inflammation, and epigenetics, making it indispensable in maintaining the basic functions of cells. Research on NAD+ has become a hotspot, particularly regarding its potential in cardiovascular disease (CVD). Many studies have demonstrated that NAD+ plays a crucial role in the occurrence and development of CVD. This review summarizes the biosynthesis and consumption of NAD+, along with its precursors and their effects on raising NAD+ levels. We also discuss new mechanisms of NAD+ regulation in cardiovascular risk factors and its effects of NAD+ on atherosclerosis, aortic aneurysm, heart failure, hypertension, myocardial ischemia-reperfusion injury, diabetic cardiomyopathy, and dilated cardiomyopathy, elucidating different mechanisms and potential treatments. NAD+-centered therapy holds promising advantages and prospects in the field of CVD.

NAD+ boosting increases atherosclerotic plaques and inflammation in Apoe knockout mice

BACKGROUND AND AIMS

NAD+ (nicotinamide adenine dinucleotide) is a cosubstrate of the sirtuins (SIRT) that are activated upon caloric restriction. Supplementing NAD+ precursors such as nicotinamide riboside (NR) has been reported to extend life span and combat metabolic syndrome through pan-sirtuin activation in mice. Notably, sirtuins compete with poly (ADP-ribose) polymerase (PARP)1 and CD38 for NAD+. Supplementing NAD+ precursors did not improve cardiovascular outcome in the AIM-HIGH trial. Recently, the terminal NAD+ metabolite 4PY (N1-methyl-4-pyridone-3-carboxamide) was reported to increase inflammation and to be associated with cardiovascular risk. We aimed to investigate whether NR provides atheroprotection.

METHODS

8-week-old male apolipoprotein E (Apoe) knockout mice were fed for 12 weeks a high-cholesterol diet supplemented with three NR doses: NR-, NR+, and NR++. RAW264.7 mouse macrophages and bone marrow macrophages were stimulated with oxLDL and NR.

RESULTS

NR++ enhanced plaque lesions in aortic sinus sections and increased plasma levels of TNFα, IL-6, and LDL-cholesterol. Liver and plasma NAD+ concentrations remained unchanged, but the downstream metabolite 4PY increased. In liver lysates, SIRT1 and lipoprotein receptors were decreased and CD38 increased in NR++; cleaved PARP1 and total PARylation decreased upon NR supplementation. In oxLDL-treated macrophages, high NR levels increased CD38 and CD86 expression.

CONCLUSIONS

High-dose NR supplementation in mice did not decrease but increase both aortic plaque lesions and systemic inflammation. These effects may be mediated by increased CD38 expression in macrophages, with NAD+ metabolism shifted from sirtuins towards CD38 and PARP1 pathways. Caution should be applied with presumed NAD+ boosters in patients with atherosclerosis.

A mixed-mode LC-MS-based method for comprehensive analysis of NAD and related metabolites from biological sample matrices

Nicotinamide adenine dinucleotide (NAD+) is an essential metabolite contributing to cellular energy needs and its decline is associated with age-related disorders. Comprehensive analysis of the NAD+ landscape following NAD+ supplementation therapies would provide a broader understanding of impacts on NAD+ pathway biology. However, the analysis of NAD+ and its metabolites is challenging owing to their polar nature and low retention on reverse phase columns. We have developed and optimized a mixed-mode (reverse-phase/anion-exchange) chromatography-tandem mass spectrometry (LC-MS/MS) method for analysis of NAD+ precursors and their metabolic products from biological sample matrices. Attributes including mobile phase ionic strength and column temperature effects on LC-MS/MS performance were evaluated. Fit-for purpose method qualification was performed with regard to linearity, accuracy, and precision. The method described was developed to be compatible with NAD-Glo assay (bioluminescence-based plate reader assay) conditions for purposes of further validating NAD-Glo and allow for expanded NAD+ pathway profiling in NAD-Glo samples. A strong correlation (R2 = 0.94) was demonstrated between the two assays for tissue NAD+ measurements in mice treated with NAM supplementation. The LC-MS/MS and NAD-Glo data confirmed dose-dependent NAD+ boosting in mice lung and skin tissues after NAM treatment. In addition, LC-MS/MS analysis revealed that the highest dose of NAM (900 mg/kg) significantly increased NR, NMN, ADPR, NAM, and m-NAM levels. Overall, we present an LC-MS/MS based orthogonal platform to confirm NAD-Glo data and show applicability of the method to more broadly evaluate the NAD+ metabolome.

Targeting CD38 immunometabolic checkpoint improves metabolic fitness and cognition in a mouse model of Alzheimer's disease

Protective immunity, essential for brain maintenance and repair, may be compromised in Alzheimer's disease (AD). Here, using high-dimensional single-cell mass cytometry, we find a unique immunometabolic signature in circulating CD4+ T cells preceding symptom onset in individuals with familial AD, featured by the elevation of CD38 expression. Using female 5xFAD mice, a mouse model of AD, we show that treatment with an antibody directed to CD38 leads to restored metabolic fitness, improved cognitive performance, and attenuated local neuroinflammation. Comprehensive profiling across distinct immunological niches in 5xFAD mice, reveals a high level of disease-associated CD4+ T cells that produce IL-17A in the dural meninges, previously linked to cognitive decline. Targeting CD38 leads to abrogation of meningeal TH17 immunity and cortical IL-1β, breaking the negative feedback loop between these two compartments. Taken together, the present findings suggest CD38 as an immunometabolic checkpoint that could be adopted as a pre-symptomatic biomarker for early diagnosis of AD, and might also be therapeutically targeted alone or in combination with other immunotherapies for disease modification.

Plant-derived nanovesicles as novel nanotherapeutics for alleviating endothelial cell senescence-associated vascular remodeling induced by hypertension

Endothelial cell senescence contributes to vascular remodeling in hypertension, a condition that lacks specific clinical treatments. While plant-derived nanovesicles have shown anti-inflammatory properties that reduce endothelial inflammation, their role in endothelial cell senescence is less understood. Here, we isolated and purified nanovesicles from Semen Sinapis albae (SDNVs), a traditional Chinese medicine with antihypertensive properties, and evaluated their therapeutic effects on vascular remodeling in spontaneously hypertensive rats (SHRs) compared to nifedipine, a standard antihypertensive drug. SDNVs were as effective as nifedipine in reducing blood pressure and exceeded nifedipine in mitigating vascular wall thickening, collagen fiber disarray, and in decreasing senescence markers in aortic tissues. In vitro, SDNVs inhibited angiotensin II-induced senescence in human umbilical vein endothelial cells (HUVECs). miRNA and mRNA sequencing revealed that SDNVs downregulate CD38 expression through miR393a delivery, mediating their anti-senescence effects. Our results suggest that SDNVs significantly alleviate hypertension-associated vascular remodeling by targeting CD38 via miR393a, thus reducing endothelial cell senescence. Compared to conventional drugs like nifedipine, SDNVs offer a potentially more effective approach to vascular remodeling. These insights may guide the development of novel therapeutics for hypertension-induced vascular remodeling.

ZDHHC9-mediated CD38 palmitoylation stabilizes CD38 expression and promotes pancreatic cancer growth

The cluster of differentiation 38 (CD38) is a multifunctional transmembrane protein involved in numerous physiological and pathological processes including aging, neurodegenerative diseases, and tumorigenesis, hence is an attractive drug target. However, the mechanisms underlying the regulation of CD38 expression remain enigmatic. Herein, we report for the first time that CD38 is palmitoylated at Cys16, and that S-palmitoylation is required to maintain CD38 protein expression in tumor cells. Furthermore, we identify DHHC9 as the palmitoyl transferase and APT1 as the acylprotein thioesterase responsible for this crucial post-translational modification. Finally, we designed a competitive peptide of CD38 palmitoylation that decreases CD38 expression in tumor cells and suppresses tumor progression in vivo. These findings provide novel insight into CD38 regulation and highlight potential therapeutic strategies targeting CD38 palmitoylation for cancer treatment.

CD38-mediated metabolic reprogramming promotes the stability and suppressive function of regulatory T cells in tumor

In the tumor microenvironment (TME), regulatory T cells (Tregs) adapt their metabolism to thrive in low-glucose, high-lactate conditions, but the mechanisms remain unclear. Our study identifies CD38 as a key regulator of this adaptation by depleting nicotinamide adenine dinucleotide (oxidized form) (NAD+), redirecting lactate-derived pyruvate toward phosphoenolpyruvate and bypassing the tricarboxylic acid (TCA) cycle. This prevents accumulation of α-ketoglutarate, which destabilizes Tregs by inducing hypermethylation at the Foxp3 locus. Restoring NAD+ with nicotinamide mononucleotide reverses this adaptation, pushing Tregs back to the TCA cycle and reducing their suppressive function. In YUMM1.7 melanoma-bearing mice, small-molecule CD38 inhibition selectively destabilizes intratumoral Tregs, sparking robust antitumor immunity. These findings reveal that targeting the CD38-NAD+ axis disrupts Tregs metabolic adaptation and offers a strategy to enhance antitumor responses.

Healthy and premature aging of monocytes and macrophages

Aging is associated with immunosenescence, a decline in immune functions, but also with inflammaging, a chronic, low-grade inflammation, contributing to immunosenescence. Monocytes and macrophages belong to the innate immune system and aging has a profound impact on these cells, leading to functional changes and most importantly, to the secretion of pro-inflammatory cytokines and thereby contributing to inflammaging. Rheumatoid arthritis (RA) is an autoimmune disease and age is an important risk factor for developing RA. RA is associated with the early development of age-related co-morbidities like cardiovascular manifestations and osteoporosis. The immune system of RA patients shows signs of premature aging like age-inappropriate increased production of myeloid cells, accelerated telomeric erosion, and the uncontrolled production of pro-inflammatory cytokines. In this review we discuss the influence of aging on monocytes and macrophages during healthy aging and premature aging in rheumatoid arthritis.

Exploration of the relationships between immune cells, metabolic mediators, and atrial fibrillation: A bidirectional Mendelian randomization study

Studies have shown a close correlation among immune cells, plasma metabolites, and atrial fibrillation (AF). However, it is not clear if this association is related, which we used Mendelian randomization (MR) to investigate. We analyzed the association between immune cells, plasma metabolites, and AF by using summarized data from genome-wide association studies. Among them, we explored the associations between immune cells and AF by using bidirectional MR analysis. Combined with mediation analysis and multivariable MR, we further identified potential mediating plasmic metabolites. Results shows that causal relationships between 8 immune cell phenotypes and AF were identified with all 8 exhibiting reverse causality. Furthermore, 22 plasma metabolites have a causal relationship with AF. In addition, 2 immune cell phenotypes including CD25 on IgD + CD38dim and CX3CR1 on CD14 + CD16-monocyte, which were found to have causal relationships with 4 plasma metabolites, including 4-acetamidobutanoate levels, Octadecanedioylcarnitine (C18-DC) levels, Linolenate [alpha or gamma; (18:3n3 or 6)] levels, and N-acetyl-aspartyl-glutamate levels, which might be mediators. Ultimately, only 4-acetamidobutanoate levels, CD25 on IgD + CD38dim, and AF did appear to function as mediators (P-value = .030 < .05). In conclusion, immune cells and plasma metabolites are causally associated with AF. We have identified that 4-acetamidobutanoate levels appear to mediate the pathway linking CD25 on IgD + CD38dim to AF. This finding provides a new perspective for the early prevention and diagnosis of preatrial AF.

CD38 mediates nicotinamide mononucleotide base exchange to yield nicotinic acid mononucleotide

Nicotinamide mononucleotide (NMN) is a widely investigated metabolic precursor to the prominent enzyme cofactor NAD+, where it is assumed that delivery of this compound results in its direct incorporation into NAD+via the canonical salvage/recycling pathway. Surprisingly, treatment with this salvage pathway intermediate leads to increases in nicotinic acid mononucleotide (NaMN) and nicotinic acid adenine dinucleotide, two members of the Preiss-Handler/de novo pathways. In mammals, these pathways are not known to intersect prior to the production of NAD+. Here, we show that the cell surface enzyme CD38 can mediate a base-exchange reaction on NMN, whereby the nicotinamide ring is exchanged with a free nicotinic acid to yield the Preiss-Handler/de novo pathway intermediate NaMN, with in vivo small molecule inhibition of CD38 abolishing the NMN-induced increase in NaMN and nicotinic acid adenine dinucleotide. Together, these data demonstrate a new mechanism by which the salvage pathway and Preiss-Handler/de novo pathways can exchange intermediates in mammalian NAD+ biosynthesis.

Estropausal gut microbiota transplant improves measures of ovarian function in adult mice

Decline in ovarian function with age not only affects fertility but is also linked to a higher risk of age-related diseases in women (e.g. osteoporosis, dementia). Intriguingly, earlier menopause is linked to shorter lifespan; however, the underlying molecular mechanisms of ovarian aging are not well understood. Recent evidence suggests the gut microbiota may influence ovarian health. In this study, we characterized ovarian aging associated microbial profiles in mice and investigated the effect of the gut microbiome from young and estropausal female mice on ovarian health through fecal microbiota transplantation. We demonstrate that the ovarian transcriptome can be broadly remodeled after heterochronic microbiota transplantation, with a reduction in inflammation-related gene expression and trends consistent with transcriptional rejuvenation. Consistently, these mice exhibited enhanced ovarian health and increased fertility. Using metagenomics-based causal mediation analyses and serum untargeted metabolomics, we identified candidate microbial species and metabolites that may contribute to the observed effects of fecal microbiota transplantation. Our findings reveal a direct link between the gut microbiota and ovarian health.

Cellular senescence: from homeostasis to pathological implications and therapeutic strategies

Cellular aging is a multifactorial and intricately regulated physiological process with profound implications. The interaction between cellular senescence and cancer is complex and multifaceted, senescence can both promote and inhibit tumor progression through various mechanisms. M6A methylation modification regulates the aging process of cells and tissues by modulating senescence-related genes. In this review, we comprehensively discuss the characteristics of cellular senescence, the signaling pathways regulating senescence, the biomarkers of senescence, and the mechanisms of anti-senescence drugs. Notably, this review also delves into the complex interactions between senescence and cancer, emphasizing the dual role of the senescent microenvironment in tumor initiation, progression, and treatment. Finally, we thoroughly explore the function and mechanism of m6A methylation modification in cellular senescence, revealing its critical role in regulating gene expression and maintaining cellular homeostasis. In conclusion, this review provides a comprehensive perspective on the molecular mechanisms and biological significance of cellular senescence and offers new insights for the development of anti-senescence strategies.

NAD World 3.0: the importance of the NMN transporter and eNAMPT in mammalian aging and longevity control

Over the past five years, systemic NAD+ (nicotinamide adenine dinucleotide) decline has been accepted to be a key driving force of aging in the field of aging research. The original version of the NAD World concept was proposed in 2009, providing an integrated view of the NAD+-centric, systemic regulatory network for mammalian aging and longevity control. The reformulated version of the concept, the NAD World 2.0, was then proposed in 2016, emphasizing the importance of the inter-tissue communications between the hypothalamus and peripheral tissues including adipose tissue and skeletal muscle. There has been significant progress in our understanding of the importance of nicotinamide mononucleotide (NMN), a key NAD+ intermediate, and nicotinamide phosphoribosyltransferase (NAMPT), particularly extracellular NAMPT (eNAMPT). With these exciting developments, the further reformulated version of the concept, the NAD World 3.0, is now proposed, featuring multi-layered feedback loops mediated by NMN and eNAMPT for mammalian aging and longevity control.

Chronological versus immunological aging: Immune rejuvenation to arrest cognitive decline

The contemporary understanding that the immune response significantly supports higher brain functions has emphasized the notion that the brain's condition is linked in a complex manner to the state of the immune system. It is therefore not surprising that immunity is a key factor in shaping brain aging. In this perspective article, we propose amending the Latin phrase "mens sana in corpore sano" ("a healthy mind in a healthy body") to "a healthy mind in a healthy immune system." Briefly, we discuss the emerging understanding of the pivotal role of the immune system in supporting lifelong brain maintenance, how the aging of the immune system impacts the brain, and how the potential rejuvenation of the immune system could, in turn, help revitalize brain function, with the ultimate ambitious goal of developing an anti-aging immune therapy.

Acute exercise boosts NAD+ metabolism of human peripheral blood mononuclear cells

Nicotinamide adenine dinucleotide (NAD+) coenzymes are the central electron carriers in biological energy metabolism. Low NAD+ levels are proposed as a hallmark of ageing and several diseases, which has given rise to therapeutic strategies that aim to tackle these conditions by boosting NAD+ levels. As a lifestyle factor with preventive and therapeutic effects, exercise increases NAD+ levels across various tissues, but so far human trials are mostly focused on skeletal muscle. Given that immune cells are mobilized and redistributed in response to acute exercise, we conducted two complementary trials to test the hypothesis that a single exercise session alters NAD+ metabolism of peripheral blood mononuclear cells (PBMCs). In a randomized crossover trial (DRKS00017686) with 24 young adults (12 female) we show that acute exercise increases gene expression and protein abundance of several key NAD+ metabolism enzymes with high conformity between high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT). In a longitudinal exercise trial (DRKS00029105) with 12 young adults (6 female) we confirm these results and reveal that - similar to skeletal muscle - NAD+ salvage is pivotal for PBMCs in response to exercise. Nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme of NAD+ salvage pathway, displayed a pronounced increase in gene expression during exercise, which was accompanied by elevated intracellular NAD+ levels and reduced serum levels of the NAD+ precursor nicotinamide. These results demonstrate that acute exercise triggers NAD+ biosynthesis of human PBMCs with potential implications for immunometabolism, immune effector function, and immunological exercise adaptions.

SARM1 deficiency induced depressive-like behavior via AMPKα/p-eEF2 axis to synapse dysfunction

Sterile Alpha and TIR Motif Containing 1 (SARM1) are proteins implicated in various neurological processes; however, their role in depression remains unexplored. This study investigated the contribution of SARM1 to depressive-like behaviors in a chronic stress-induced depression model and SARM1 knockout (KO) mice. Depressive-like behaviors were assessed using a battery of behavioral tests, including the Open Field Test (OFT), the Forced Swim Test (FST), the Sucrose Preference Test (SPT), and the Tail Suspension Test (TST). Mitochondrial energy metabolism alteration, cytokine level changes, and other related molecular signaling protein expression were evaluated using ELISA and western blotting techniques to investigate the underlying mechanisms. Behavioral assessments (OFT, FST, SPT, TST) revealed depressive-like phenotypes in SARM1 KO mice, accompanied by altered mitochondrial energy metabolism (NAD+, ATP) in the cortex. Intriguingly, SARM1 depletion led to peripheral inflammation, as evidenced by elevated cytokine levels in plasma but not in brain regions (cortex). In addition, we found dysregulated energy metabolism, AMPK signaling, and synaptic plasticity in the cortex of SARM1 KO mice. Notably, AICAR (Acadesine), an AMPK activator, ameliorated depressive-like behaviors and synaptic dysfunction, while Compound C, an AMPK inhibitor, reversed these effects. Additionally, NH125, an eEF2 kinase inhibitor, improved depressive-like behaviors in SARM1 KO mice. These findings demonstrate that SARM1 is critical in regulating depressive-like behaviours through the AMPKα/p-eEF2 signaling pathway. Targeting AMPK signaling and synaptic function may offer novel therapeutic avenues for depression.

Remodeling of tumor microenvironment by cellular senescence and immunosenescence in cervical cancer

Cellular senescence is a response to various stress signals, which is characterized by stable cell cycle arrest, alterations in cellular morphology, metabolic reprogramming and production of senescence-associated secretory phenotype (SASP). When it occurs in the immune system, it is called immunosenescence. Cervical cancer is a common gynecological malignancy, and cervical cancer screening is generally recommended before the age of 65. Elderly women (≥65 years) are more often diagnosed with advanced disease and have poorer prognosis compared to younger patients. Despite extensive research, the tumor microenvironment requires more in-depth exploration, particularly in elderly patients. In cervical cancer, senescent cells have a double-edged sword effect on tumor progression. Induction of preneoplastic cell senescence prevents tumor initiation, and several treatment approaches of cervical cancer act in part by inducing cancer cell senescence. However, senescent immune cell populations within the tumor microenvironment facilitate tumor development, recurrence, treatment resistance, etc. Amplification of beneficial effects and inhibition of aging-related pro-tumorigenic pathways contribute to improving antitumor effects. This review discusses senescent cancer and immune cells present in the tumor microenvironment of cervical cancer and how these senescent cells and their SASP remodel the tumor microenvironment, influence antitumor immunity and tumor initiation and development. Moreover, we discuss the significance of senotherapeutics that enable to eliminate senescent cells and prevent tumor progression and development through improving antitumor immunity and affecting the tumor microenvironment.

Decoding NAD+ Metabolism in COVID-19: Implications for Immune Modulation and Therapy

The persistent threat of COVID-19, particularly with the emergence of new variants, underscores the urgency for innovative therapeutic strategies beyond conventional antiviral treatments. Current immunotherapies, including IL-6/IL-6R monoclonal antibodies and JAK inhibitors, exhibit suboptimal efficacy, necessitating alternative approaches. Our review delves into the significance of NAD+ metabolism in COVID-19 pathology, marked by decreased NAD+ levels and upregulated NAD+-consuming enzymes such as CD38 and poly (ADP-ribose) polymerases (PARPs). Recognizing NAD+'s pivotal role in energy metabolism and immune modulation, we propose modulating NAD+ homeostasis could bolster the host's defensive capabilities against the virus. The article reviews the scientific rationale behind targeting NAD+ pathways for therapeutic benefit, utilizing strategies such as NAD+ precursor supplementation and enzyme inhibition to modulate immune function. While preliminary data are encouraging, the challenge lies in optimizing these interventions for clinical use. Future research should aim to unravel the intricate roles of key metabolites and enzymes in NAD+ metabolism and to elucidate their specific mechanisms of action. This will be essential for developing targeted NAD+ therapies, potentially transforming the management of COVID-19 and setting a precedent for addressing other infectious diseases.

Pathobiochemistry of Aging and Neurodegeneration: Deregulation of NAD+ Metabolism in Brain Cells

NAD+ plays a pivotal role in energy metabolism and adaptation to external stimuli and stressful conditions. A significant reduction in intracellular NAD+ levels is associated with aging and contributes to the development of chronic cardiovascular, neurodegenerative, and metabolic diseases. It is of particular importance to maintain optimal levels of NAD+ in cells with high energy consumption, particularly in the brain. Maintaining the tissue level of NAD+ with pharmacological tools has the potential to slow down the aging process, to prevent the development of age-related diseases. This review covers key aspects of NAD+ metabolism in terms of brain metabolic plasticity, including NAD+ biosynthesis and degradation in different types of brain cells, as well as its contribution to the development of neurodegeneration and aging, and highlights up-to-date approaches to modulate NAD+ levels in brain cells.

SenNet recommendations for detecting senescent cells in different tissues

Once considered a tissue culture-specific phenomenon, cellular senescence has now been linked to various biological processes with both beneficial and detrimental roles in humans, rodents and other species. Much of our understanding of senescent cell biology still originates from tissue culture studies, where each cell in the culture is driven to an irreversible cell cycle arrest. By contrast, in tissues, these cells are relatively rare and difficult to characterize, and it is now established that fully differentiated, postmitotic cells can also acquire a senescence phenotype. The SenNet Biomarkers Working Group was formed to provide recommendations for the use of cellular senescence markers to identify and characterize senescent cells in tissues. Here, we provide recommendations for detecting senescent cells in different tissues based on a comprehensive analysis of existing literature reporting senescence markers in 14 tissues in mice and humans. We discuss some of the recent advances in detecting and characterizing cellular senescence, including molecular senescence signatures and morphological features, and the use of circulating markers. We aim for this work to be a valuable resource for both seasoned investigators in senescence-related studies and newcomers to the field.

Nicotinamide Riboside and CD38: Covalent Inhibition and Live-Cell Labeling

Nicotinamide adenine dinucleotide (NAD+) is required for a myriad of metabolic, signaling, and post-translational events in cells. Its levels in tissues and organs are closely associated with health conditions. The homeostasis of NAD+ is regulated by biosynthetic pathways and consuming enzymes. As a membrane-bound protein with robust NAD+ hydrolase activity, cluster of differentiation 38 (CD38) is a major degrader of NAD+. Deficiency or inhibition of CD38 enhances NAD+ levels in vivo, resulting in various therapeutic benefits. As a metabolic precursor of NAD+, nicotinamide mononucleotide can be rapidly hydrolyzed by CD38, whereas nicotinamide riboside (NR) lacks CD38 substrate activity. Given their structural similarities, we explored the inhibition potential of NR. To our surprise, NR exhibits marked inhibitory activity against CD38 by forming a stable ribosyl-ester bond with the glutamate residue 226 at the active site. Inspired by this discovery, we designed and synthesized a clickable NR featuring an azido substitution at the 5'-OH position. This cell-permeable NR analogue enables covalent labeling and imaging of both extracellular and intracellular CD38 in live cells. Our work discovers an unrecognized molecular function of NR and generates a covalent probe for health-related CD38. These findings offer new insights into the role of NR in modulating NAD+ metabolism and CD38-mediated signaling as well as an innovative tool for in-depth studies of CD38 in physiology and pathophysiology.

Organoids as Tools for Investigating Skin Aging: Mechanisms, Applications, and Insights

Organoids have emerged as transformative tools in biomedical research, renowned for their ability to replicate the complexity construct of human tissues. Skin aging is a multifaceted biological process, influenced by both intrinsic factors and extrinsic factors. Traditional models for studying skin aging often fall short in capturing the intricate dynamics of human skin. In contrast, skin organoids offer a more physiologically relevant system, reflecting the structural and functional characteristics of native skin. These characteristics make skin organoids highly suitable for studying the mechanisms of skin aging, identifying novel therapeutic targets, and testing anti-aging interventions. Despite their promise, challenges such as limited scalability, reproducibility, and ethical considerations remain. Addressing these hurdles through interdisciplinary research and technological advancements will be essential to maximizing the potential of skin organoids for dermatological research and personalized anti-aging therapies.

Functional identification of soluble uric acid as an endogenous inhibitor of CD38

Excessive elevation or reduction of soluble uric acid (sUA) levels has been linked to some of pathological states, raising another subject that sUA at physiological levels may be essential for the maintenance of health. Yet, the fundamental physiological functions and molecular targets of sUA remain largely unknown. Using enzyme assays and in vitro and in vivo metabolic assays, we demonstrate that sUA directly inhibits the hydrolase and cyclase activities of CD38 via a reversible non-competitive mechanism, thereby limiting nicotinamide adenine dinucleotide (NAD+) degradation. CD38 inhibition is restricted to sUA in purine metabolism, and a structural comparison using methyl analogs of sUA such as caffeine metabolites shows that 1,3-dihydroimidazol-2-one is the main functional group. Moreover, sUA at physiological levels prevents crude lipopolysaccharide (cLPS)-induced systemic inflammation and monosodium urate (MSU) crystal-induced peritonitis in mice by interacting with CD38. Together, this study unveils an unexpected physiological role for sUA in controlling NAD+ availability and innate immunity through CD38 inhibition, providing a new perspective on sUA homeostasis and purine metabolism.

Immunometabolism: signaling pathways, homeostasis, and therapeutic targets

Immunometabolism plays a central role in sustaining immune system functionality and preserving physiological homeostasis within the organism. During the differentiation and activation, immune cells undergo metabolic reprogramming mediated by complex signaling pathways. Immune cells maintain homeostasis and are influenced by metabolic microenvironmental cues. A series of immunometabolic enzymes modulate immune cell function by metabolizing nutrients and accumulating metabolic products. These enzymes reverse immune cells' differentiation, disrupt intracellular signaling pathways, and regulate immune responses, thereby influencing disease progression. The huge population of immune metabolic enzymes, the ubiquity, and the complexity of metabolic regulation have kept the immune metabolic mechanisms related to many diseases from being discovered, and what has been revealed so far is only the tip of the iceberg. This review comprehensively summarized the immune metabolic enzymes' role in multiple immune cells such as T cells, macrophages, natural killer cells, and dendritic cells. By classifying and dissecting the immunometabolism mechanisms and the implications in diseases, summarizing and analyzing advancements in research and clinical applications of the inhibitors targeting these enzymes, this review is intended to provide a new perspective concerning immune metabolic enzymes for understanding the immune system, and offer novel insight into future therapeutic interventions.

Cellular senescence and its pathogenic and therapeutic implications in autoimmune hepatitis

INTRODUCTION

Senescent cells are characterized by replicative arrest and phenotypes that produce diverse pro-inflammatory and pro-oxidant mediators. The senescence of diverse hepatic cell types could constitute an unrecognized pathogenic mechanism and prognostic determinant in autoimmune hepatitis. The impact of cellular senescence in autoimmune hepatitis is unknown, and it may suggest adjunctive management strategies.

AREAS COVERED

This review describes the molecular mechanisms of cellular senescence, indicates its diagnostic features, suggests its consequences, presents possible therapeutic interventions, and encourages investigations of its pathogenic role and management in autoimmune hepatitis. Treatment prospects include elimination or reversal of senescent cells, generation of ectopic telomerase, reactivation of dormant telomerase, neutralization of specific pro-inflammatory secretory products, and mitigation of the effects of mitochondrial dysfunction.

EXPERT OPINION

The occurrence, nature, and consequences of cellular senescence in autoimmune hepatitis must be determined. The senescence of diverse hepatic cell types could affect the outcome of autoimmune hepatitis by impairing hepatic regeneration, intensifying liver inflammation, and worsening hepatic fibrosis. Cellular senescence could contribute to suboptimal responses during conventional glucocorticoid-based therapy. Interventions that target specific pro-inflammatory products of the senescent phenotype or selectively promote apoptosis of senescent cells may be preferred adjunctive treatments for autoimmune hepatitis depending on the cancer risk.

Deletion of CD38 mitigates the severity of NEC in experimental settings by modulating macrophage-mediated inflammation

Necrotizing enterocolitis (NEC) is a form of potentially lethal gastrointestinal inflammation that primarily affects preterm neonates. It is crucial to recognize that, while the disease carries significant risks, timely and effective medical intervention can greatly enhance the chances of survival. Additionally, NEC is closely linked to the activation of macrophages, highlighting the complex interplay between the immune response and disease progression. CD38, acting as an ectoenzyme, catalyzes the hydrolysis of NAD+ to produce cyclic ADP-ribose (cADPR), a reaction critical for modulating cellular redox balance and energy homeostasis. This enzymatic activity is particularly pertinent in the context of necrotizing enterocolitis (NEC). In this research, we investigated whether CD38 deletion can elevate NAD+ levels to reduce macrophage-mediated inflammation and improve NEC severity. We show that NEC patients was associated with the increased CD38 expression in intestine and blood. These results were also observed in NEC mice, and CD38 deletion ameliorated NEC intestinal injury. Mechanistically, CD38 deletion elevated NAD+ levels that reduced oxidative stress and intestinal inflammation. Furthermore, CD38 deletion promoted M2 macrophage polarization, inhibited macrophage activation and phagocytosis ability. Thus, our results reveal a critical role for CD38 as an intracellular immune regulator for regulating macrophage activation and intestinal inflammation in NEC. Targeting CD38 and NAD+ signal maybe a promising strategy for treatment of NEC.

TRPM2 channels are essential for regulation of cytokine production in lung interstitial macrophages

Interstitial macrophages (IMs) are essential for organ homeostasis, inflammation, and autonomous immune response in lung tissues, which are achieved through polarization to a pro-inflammatory M1 and an M2 state for tissue repair. Their remote parenchymal localization and low counts, however, are limiting factors for their isolation and molecular characterization of their specific role during tissue inflammation. We isolated viable murine IMs in sufficient quantities by coculturing them with stromal cells and analyzed mRNA expression patterns of transient receptor potential (TRP) channels in naïve and M1 polarized IMs after application of lipopolysaccharide (LPS) and interferon γ. M-RNAs for the second member of the melastatin family of TRP channels, TRPM2, were upregulated in the M1 state and functional channels were identified by their characteristic currents induced by ADP-ribose, its specific activator. Most interestingly, cytokine production and secretion of interleukin-1α (IL-1α), IL-6 and tumor necrosis factor-α in M1 polarized but TRPM2-deficient IMs was significantly enhanced compared to WT cells. Activation of TRPM2 channels by ADP-ribose (ADPR) released from mitochondria by ROS-produced H2O2 significantly increases plasma membrane depolarization, which inhibits production of reactive oxygen species by NADPH oxidases and reduces cytokine production and secretion in a negative feedback loop. Therefore, TRPM2 channels are essential for the regulation of cytokine production in M1-polarized murine IMs. Specific activation of these channels may promote an anti-inflammatory phenotype and prevent a harmful cytokine storm often observed in COVID-19 patients.

A biocompatible polydopamine platform for targeted delivery of nicotinamide mononucleotide and boosting NAD+ levels in the brain

Nicotinamide mononucleotide (NMN), a precursor of the coenzyme nicotinamide adenine dinucleotide (NAD+), has gained wide attention as an anti-aging agent, which plays a significant role in intracellular redox reactions. However, its effectiveness is limited by easy metabolism in the liver and subsequent excretion as nicotinamide, resulting in low bioavailability, particularly in the brain. Additionally, the blood-brain barrier (BBB) further hinders NMN supply to the brain, compromising its potential anti-aging effects. Herein, we developed a biocompatible polydopamine (PDA) platform to deliver NMN for boosting NAD+ levels in the brain for the first time. The lactoferrin (Lf) ligand was covalently attached to the PDA spheres to improve BBB transport efficiency. The resultant PDA-based system, referred to as PDA-Lf-NMN, not only exhibited superior BBB penetration ability but also improved the utilization rate of brain NMN in elevating NAD+ levels compared to NMN alone for both young (3 months) and old (21 months) mice. Moreover, after the old mice were treated with low-dose PDA-Lf-NMN (8 mg kg-1 day-1), they exhibited improved spatial cognition. Importantly, these nanomedicines did not induce any cellular necrosis or apoptosis. It provides a promising avenue for delivering NMN specifically to the brain, boosting NAD+ levels for promoting longevity and treating brain aging-related diseases.

Nerve-associated macrophages control adipose homeostasis across lifespan and restrain age-related inflammation

Age-related inflammation or inflammaging is a key mechanism that increases disease burden and may control lifespan. How adipose tissue macrophages (ATMs) control inflammaging is not well understood in part because the molecular identities of niche-specific ATMs are incompletely known. Using intravascular labeling to exclude circulating myeloid cells and subsequent single-cell sequencing with orthogonal validation, we define the diversity and alterations in niche resident ATMs through lifespan. Aging led to depletion of vessel-associated macrophages (VAMs), expansion of lipid-associated macrophages (LAMs), and emergence of a unique subset of CD38+ age-associated macrophages (AAMs) in visceral white adipose tissue (VAT). Interestingly, CD169+CD11c- ATMs are enriched in a subpopulation of nerve-associated macrophages (NAMs) that declines with age. Depletion of CD169+ NAMs in aged mice increases inflammaging and impairs lipolysis suggesting that they are necessary for preventing catecholamine resistance in VAT. These findings reveal specialized ATMs control adipose homeostasis and link inflammation to tissue dysfunction during aging.

Multiple myeloma and the potential of new checkpoint inhibitors for immunotherapy

Multiple myeloma (MM), a cancer of the bone marrow, is categorized as the second most common hematological malignancy of adults in the Western world. Despite dramatic improvements in immunotherapies in the field of cancers, MM immunotherapy has not been promising until now. Recent clinical studies of immune checkpoint inhibitor therapy, either alone or in combination with anticancer drugs, showed excessive side effects or low efficacy, particularly in advanced MM patients. In this context, lymphocyte levels of exhaustion markers play a pivotal role in the MM tumor microenvironment (TME). Hence in the present review, the mechanisms relevant to MM of five inhibitory molecules including T-cell immunoreceptor with Ig and ITIM domains (TIGIT), T-cell immunoglobulin, and mucin domain 3 (Tim-3), lymphocyte activation gene-3 (LAG-3), V-domain Ig Suppressor of T-cell activation and killer immunoglobulin-like receptors along with bispecific T-cell antibodies (BsAbs) will be discussed. Further, we summarized the underlying biology of these checkpoints in cancer and their rapidly emerging role in pathways in MM along with presenting recent clinical trials in context.

Multidimensional profiling of human T cells reveals high CD38 expression, marking recent thymic emigrants and age-related naive T cell remodeling

Thymic involution is a key factor in human immune aging, leading to reduced thymic output and a decline in recent thymic emigrant (RTE) naive T cells in circulation. Currently, the precise definition of human RTEs and their corresponding cell surface markers lacks clarity. Analysis of single-cell RNA-seq/ATAC-seq data distinguished RTEs by the expression of SOX4, IKZF2, and TOX and CD38 protein, whereby surface CD38hi expression universally identified CD8+ and CD4+ RTEs. We further determined the dynamics of RTEs and mature cells in a cohort of 158 individuals, including age-associated transcriptional reprogramming and shifts in cytokine production. Spectral cytometry profiling revealed two axes of aging common to naive CD8+ and CD4+ T cells: (1) a decrease in CD38++ cells (RTEs) and (2) an increase in CXCR3hi cells. Identification of RTEs enables direct assessment of thymic health. Furthermore, resolving the dynamics of naive T cell remodeling yields insight into vaccination and infection responsiveness throughout aging.

Connecting the Dots: Telomere Shortening and Rheumatic Diseases

Telomeres, repetitive sequences located at the extremities of chromosomes, play a pivotal role in sustaining chromosomal stability. Telomerase is a complex enzyme that can elongate telomeres by appending telomeric repeats to chromosome ends and acts as a critical factor in telomere dynamics. The gradual shortening of telomeres over time is a hallmark of cellular senescence and cellular death. Notably, telomere shortening appears to result from the complex interplay of two primary mechanisms: telomere shelterin complexes and telomerase activity. The intricate interplay of genetic, environmental, and lifestyle influences can perturb telomere replication, incite oxidative stress damage, and modulate telomerase activity, collectively resulting in shifts in telomere length. This age-related process of telomere shortening plays a considerable role in various chronic inflammatory and oxidative stress conditions, including cancer, cardiovascular disease, and rheumatic disease. Existing evidence has shown that abnormal telomere shortening or telomerase activity abnormalities are present in the pathophysiological processes of most rheumatic diseases, including different disease stages and cell types. The impact of telomere shortening on rheumatic diseases is multifaceted. This review summarizes the current understanding of the link between telomere length and rheumatic diseases in clinical patients and examines probable telomere shortening in peripheral blood mononuclear cells and histiocytes. Therefore, understanding the intricate interaction between telomere shortening and various rheumatic diseases will help in designing personalized treatment and control measures for rheumatic disease.

Metabolome and Transcriptome Profiling Reveals Age-Associated Variations in Meat Quality and Molecular Mechanisms of Taihe Black-Bone Silky Fowls

To explore the changes in meat quality and molecular mechanisms during the growth and development of Taihe black-bone silky fowl, this study employed liquid chromatography-mass spectrometry (LC-MS/MS) metabolomics to elucidate the dynamic changes of key differential metabolites (DMs) affecting meat quality, indicating that chicken at D120 had higher levels of ω-3 polyunsaturated fatty acids (PUFAs), creatine, anserine, and homocarnosine, while D150 had the most stachydrine and D210 had the most acylcarnitines. Additionally, D120 and D180 had more umami and sweet compounds. Furthermore, key metabolic pathways influenced by age included purine metabolism, the pentose phosphate pathway, nicotinate and nicotinamide metabolism, and taurine and hypotaurine metabolism. Transcriptomic identified differential expression genes (DEGs) are predominantly enriched in focal adhesion, the TGF-β signaling pathway, and the MAPK signaling pathway. Integrated metabolomics and transcriptomics revealed complex regulatory networks of DEGs and DMs in key metabolic pathways. This research enhanced our understanding of the biology of Taihe black-bone silky fowl meat quality, revealing possible biomarkers.

Regulation of and challenges in targeting NAD+ metabolism

Nicotinamide adenine dinucleotide, in its oxidized (NAD+) and reduced (NADH) forms, is a reduction-oxidation (redox) co-factor and substrate for signalling enzymes that have essential roles in metabolism. The recognition that NAD+ levels fall in response to stress and can be readily replenished through supplementation has fostered great interest in the potential benefits of increasing or restoring NAD+ levels in humans to prevent or delay diseases and degenerative processes. However, much about the biology of NAD+ and related molecules remains poorly understood. In this Review, we discuss the current knowledge of NAD+ metabolism, including limitations of, assumptions about and unappreciated factors that might influence the success or contribute to risks of NAD+ supplementation. We highlight several ongoing controversies in the field, and discuss the role of the microbiome in modulating the availability of NAD+ precursors such as nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN), the presence of multiple cellular compartments that have distinct pools of NAD+ and NADH, and non-canonical NAD+ and NADH degradation pathways. We conclude that a substantial investment in understanding the fundamental biology of NAD+, its detection and its metabolites in specific cells and cellular compartments is needed to support current translational efforts to safely boost NAD+ levels in humans.

CD38 and the mitochondrial calcium uniporter contribute to age-related hematopoietic stem cell dysfunction

Hematopoietic stem cells (HSCs) are the multipotent progenitors of all immune cells. During aging, their regenerative capacity decreases for reasons that are not well understood. Recently, Song et al investigated the roles of two metabolic proteins in age-related HSC dysfunction: CD38 (a membrane-bound NADase) and the mitochondrial calcium uniporter that transports calcium into the mitochondrial matrix. They found that the interplay between these proteins is deranged in aged HSCs, contributing to their diminished renewal capacity. These findings implicate compromised nicotinamide adenine dinucleotide metabolism as underlying HSC dysfunction in aging.

CD38 in SLE CD4 T cells promotes Ca2+ flux and suppresses interleukin-2 production by enhancing the expression of GM2 on the surface membrane

CD38 has emerged as a potential therapeutic target for patients with systemic lupus erythematosus (SLE) but it is not known whether CD38 alters CD4+ T cell function. Using primary human T cells and CD38-sufficient and CD38-deficient Jurkat T cells, we demonstrate that CD38 shifts the T cell lipid profile of gangliosides from GM3 to GM2 by upregulating B4GALNT1 in a Sirtuin 1-dependent manner. Enhanced expression of GM2 causes ER stress by enhancing Ca2+ flux through the PLCγ1-IP3 pathway. Interestingly, correction of the calcium overload by an IP3 receptor inhibitor, but not by a store-operated calcium entry (SOCE) inhibitor, improves IL-2 production by CD4+ T cells in SLE. This study demonstrates that CD38 affects calcium homeostasis in CD4+ T cells by controlling cell membrane lipid composition that results in suppressed IL-2 production. CD38 inhibition with biologics or small drugs should be expected to benefit patients with SLE.

The role of mitochondria in cytokine and chemokine signalling during ageing

Ageing is accompanied by a persistent, low-level inflammation, termed "inflammageing", which contributes to the pathogenesis of age-related diseases. Mitochondria fulfil multiple roles in host immune responses, while mitochondrial dysfunction, a hallmark of ageing, has been shown to promote chronic inflammatory states by regulating the production of cytokines and chemokines. In this review, we aim to disentangle the molecular mechanisms underlying this process. We describe the role of mitochondrial signalling components such as mitochondrial DNA, mitochondrial RNA, N-formylated peptides, ROS, cardiolipin, cytochrome c, mitochondrial metabolites, potassium efflux and mitochondrial calcium in the age-related immune system activation. Furthermore, we discuss the effect of age-related decline in mitochondrial quality control mechanisms, including mitochondrial biogenesis, dynamics, mitophagy and UPRmt, in inflammatory states upon ageing. In addition, we focus on the dynamic relationship between mitochondrial dysfunction and cellular senescence and its role in regulating the secretion of pro-inflammatory molecules by senescent cells. Finally, we review the existing literature regarding mitochondrial dysfunction and inflammation in specific age-related pathological conditions, including neurodegenerative diseases (Alzheimer's and Parkinson's disease, and amyotrophic lateral sclerosis), osteoarthritis and sarcopenia.

Research advances in the function and anti-aging effects of nicotinamide mononucleotide

Aging and age-related ailments have emerged as critical challenges and great burdens within the global contemporary society. Addressing these concerns is an imperative task, with the aims of postponing the aging process and finding effective treatments for age-related degenerative diseases. Recent investigations have highlighted the significant roles of nicotinamide adenine dinucleotide (NAD+) in the realm of anti-aging. It has been empirically evidenced that supplementation with nicotinamide mononucleotide (NMN) can elevate NAD+ levels in the body, thereby ameliorating certain age-related degenerative diseases. The principal anti-aging mechanisms of NMN essentially lie in its impact on cellular energy metabolism, inhibition of cell apoptosis, modulation of immune function, and preservation of genomic stability, which collectively contribute to the deferral of the aging process. This paper critically reviews and evaluates existing research on the anti-aging mechanisms of NMN, elucidates the inherent limitations of current research, and proposes novel avenues for anti-aging investigations.

IL36G-producing neutrophil-like monocytes promote cachexia in cancer

Most patients with advanced cancer develop cachexia, a multifactorial syndrome characterized by progressive skeletal muscle wasting. Despite its catastrophic impact on survival, the critical mediators responsible for cancer cachexia development remain poorly defined. Here, we show that a distinct subset of neutrophil-like monocytes, which we term cachexia-inducible monocytes (CiMs), emerges in the advanced cancer milieu and promotes skeletal muscle loss. Unbiased transcriptome analysis reveals that interleukin 36 gamma (IL36G)-producing CD38+ CiMs are induced in chronic monocytic blood cancer characterized by prominent cachexia. Notably, the emergence of CiMs and the activation of CiM-related gene signatures in monocytes are confirmed in various advanced solid cancers. Stimuli of toll-like receptor 4 signaling are responsible for the induction of CiMs. Genetic inhibition of IL36G-mediated signaling attenuates skeletal muscle loss and rescues cachexia phenotypes in advanced cancer models. These findings indicate that the IL36G-producing subset of neutrophil-like monocytes could be a potential therapeutic target in cancer cachexia.

Targeting Cell Senescence and Senolytics: Novel Interventions for Age-Related Endocrine Dysfunction

Multiple changes occur in hormonal regulation with aging and across various endocrine organs. These changes are associated with multiple age-related disorders and diseases. A better understanding of responsible underling biological mechanisms could help in the management of multiple endocrine disorders over and above hormone replacement therapy (HRT). Cellular senescence is involved in multiple biological aging processes and pathologies common in elderly individuals. Cellular senescence, which occurs in many older individuals but also across the lifespan in association with tissue damage, acute and chronic diseases, certain drugs, and genetic syndromes, may contribute to such endocrine disorders as osteoporosis, metabolic syndrome, and type 2 diabetes mellitus. Drugs that selectively induce senescent cell removal, "senolytics,", and drugs that attenuate the tissue-destructive secretory state of certain senescent cells, "senomorphics," appear to delay the onset of or alleviate multiple diseases, including but not limited to endocrine disorders such as diabetes, complications of obesity, age-related osteoporosis, and cancers as well as atherosclerosis, chronic kidney disease, neurodegenerative disorders, and many others. More than 30 clinical trials of senolytic and senomorphic agents have already been completed, are underway, or are planned for a variety of indications. Targeting senescent cells is a novel strategy that is distinct from conventional therapies such as HRT, and thus might address unmet medical needs and can potentially amplify effects of established endocrine drug regimens, perhaps allowing for dose decreases and reducing side effects.

Adipose tissue senescence: Biological changes, hallmarks and therapeutic approaches

Adipose tissue (AT), the largest energy storage reservoir and endocrine organ, plays a crucial role in regulating systemic energy metabolism. As one of the most vulnerable tissues during aging, the plasticity of AT is impaired. With age, AT undergoes redistribution, characterized by expansion of visceral adipose tissue (VAT) and reduction of peripheral subcutaneous adipose tissue (SAT). Additionally, age-related changes in AT include reduced adipogenesis of white adipocytes, decreased proliferation and differentiation capacity of mesenchymal stromal/stem cells (MSCs), diminished thermogenic capacity in brown/beige adipocytes, and dysregulation of immune cells. Specific and sensitive hallmarks enable the monitoring and evaluation of the biological changes associated with aging. In this study, we have innovatively proposed seven characteristic hallmarks of AT senescence, including telomere attrition, epigenetic alterations, genomic instability, mitochondrial dysfunction, disabled macroautophagy, cellular senescence, and chronic inflammation, which are intricately interconnected and mutually regulated. Finally, we discussed anti-aging strategies targeting AT, offering insights into mitigating or delaying metabolic disturbances caused by AT senescence.

The ecto-enzyme CD38 modulates CD4T cell immunometabolic responses and participates in HIV pathogenesis

Despite abundant evidence correlating T cell CD38 expression and HIV infection pathogenesis, its role as a CD4T cell immunometabolic regulator remains unclear. We find that CD38's extracellular glycohydrolase activity restricts metabolic reprogramming after T cell receptor (TCR)-engaging stimulation in Jurkat T CD4 cells, together with functional responses, while reducing intracellular nicotinamide adenine dinucleotide and nicotinamide mononucleotide concentrations. Selective elimination of CD38's ectoenzyme function licenses them to decrease the oxygen consumption rate/extracellular acidification rate ratio upon TCR signaling and to increase cycling, proliferation, survival, and CD40L induction. Pharmacological inhibition of ecto-CD38 catalytic activity in TM cells from chronic HIV-infected patients rescued TCR-triggered responses, including differentiation and effector functions, while reverting abnormally increased basal glycolysis, cycling, and spontaneous proinflammatory cytokine production. Additionally, ecto-CD38 blockage normalized basal and TCR-induced mitochondrial morphofunctionality, while increasing respiratory capacity in cells from HIV+ patients and healthy individuals. Ectoenzyme CD38's immunometabolic restriction of TCR-involving stimulation is relevant to CD4T cell biology and to the deleterious effects of CD38 overexpression in HIV disease.

T-Cell Senescence in Human Metabolic Diseases

Immunosenescence denotes a state of dysregulated immune cell function characterized by a confluence of factors, including arrested cell cycle, telomere shortening, markers of cellular stress, mitochondrial dysfunction, loss of proteostasis, epigenetic reprogramming, and secretion of proinflammatory mediators. This state primarily manifests during the aging process but can also be induced in various pathological conditions, encompassing chronic viral infections, autoimmune diseases, and metabolic disorders. Age-associated immune system alterations extend to innate and adaptive immune cells, with T-cells exhibiting heightened susceptibility to immunosenescence. In particular, senescent T-cells have been identified in the context of metabolic disorders such as obesity, diabetes, and cardiovascular diseases. Recent investigations suggest a direct link between T-cell senescence, inflammation, and insulin resistance. The perturbation of biological homeostasis by senescent T-cells appears intricately linked to the initiation and progression of metabolic diseases, particularly through inflammation-mediated insulin resistance. Consequently, senescent T-cells are emerging as a noteworthy therapeutic target. This review aims to elucidate the intricate relationship between metabolic diseases and T-cell senescence, providing insights into the potential roles of senescent T-cells in the pathogenesis of metabolic disorders. Through a comprehensive examination of current research findings, this review seeks to contribute to a deeper understanding of the complex interplay between immunosenescence and metabolic health.

Idebenone Antagonizes P53-Mediated Neuronal Oxidative Stress Injury by Regulating CD38-SIRT3 Protein Level

Idebenone, an antioxidant used in treating oxidative damage-related diseases, has unclear neuroprotective mechanisms. Oxidative stress affects cell and mitochondrial membranes, altering Adp-ribosyl cyclase (CD38) and Silent message regulator 3 (SIRT3) protein expression and possibly impacting SIRT3's ability to deacetylate Tumor protein p53 (P53). This study explores the relationship between CD38, SIRT3, and P53 in H2O2-injured HT22 cells treated with Idebenone. Apoptosis was detected using flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining after determining appropriate H2O2 and Idebenone concentrations.In this study, Idebenone was found to reduce apoptosis and decrease P53 and Caspase3 expression in H2O2-injured HT22 cells by detecting apoptosis-related protein expression. Through bioinformatics methods, CD38 was identified as the target of Idebenone, and it further demonstrated that Idebenone decreased the expression of CD38 and increased the level of SIRT3. An increased NAD+/NADH ratio was detected, suggesting Idebenone induces SIRT3 expression and protects HT22 cells by decreasing apoptosis-related proteins. Knocking down SIRT3 downregulated acetylated P53 (P53Ac), indicating SIRT3's importance in P53 deacetylation.These results supported that CD38 was used as a target of Idebenone to up-regulate SIRT3 to deacetylate activated P53, thereby protecting HT22 cells from oxidative stress injury. Thus, Idebenone is a drug that may show great potential in protecting against reactive oxygen species (ROS) induced diseases such as Parkinson's disease, and Alzheimer's disease. And it might be able to compensate for some of the defects associated with CD38-related diseases.

NAD+ metabolism and therapeutic strategies in cardiovascular diseases

Nicotinamide adenine dinucleotide (NAD+) is a central and pleiotropic metabolite involved in cellular energy metabolism, cell signaling, DNA repair, and protein modifications. Cardiovascular diseases (CVDs) are the leading cause of death worldwide. Metabolic stress and aging directly affect the cardiovascular system. Compelling data suggest that NAD + levels decrease with age, obesity, and hypertension, which are all notable risk factors for CVD. In addition, the therapeutic elevation of NAD + levels reduces chronic low-grade inflammation, reactivates autophagy and mitochondrial biogenesis, and enhances oxidative metabolism in vascular cells of humans and rodents with vascular disorders. In preclinical models, NAD + boosting can also expand the health span, prevent metabolic syndrome, and decrease blood pressure. Moreover, NAD + storage by genetic, pharmacological, or natural dietary NAD + -increasing strategies has recently been shown to be effective in improving the pathophysiology of cardiac and vascular health in different animal models, and human health. Here, we review and discuss NAD + -related mechanisms pivotal for vascular health and summarize recent experimental evidence in NAD + research directly related to vascular disease, including atherosclerosis, and coronary artery disease. Finally, we comparatively assess distinct NAD + precursors for their clinical efficacy and the efficiency of NAD + elevation in the treatment of major CVD. These findings may provide ideas for new therapeutic strategies to prevent and treat CVD in the clinic.