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Generally, fasting and refeeding confer anti- and proinflammatory effects, respectively. In humans, these caloric-load interventions function, in part, via regulation of CD4+ T cell biology. However, mechanisms orchestrating this regulation remain incomplete. We employed integrative bioinformatics of RNA sequencing and high-performance liquid chromatography–mass spectrometry data to measure serum metabolites and gene expression of peripheral blood mononuclear cells isolated from fasting and refeeding in volunteers to identify nutrient-load metabolite-driven immunoregulation. Propionate, a short chain fatty acid (SCFA), and the SCFA-sensing G protein–coupled receptor 43 (ffar2) were coordinately and inversely regulated by fasting and refeeding. Propionate and free fatty acid receptor agonists decreased interferon-γ and interleukin-17 and significantly blunted histone deacetylase activity in CD4+ T cells. Furthermore, propionate blunted nuclear factor κB activity and diminished interleukin-6 release. In parallel, propionate reduced phosphorylation of canonical T helper 1 (TH1) and TH17 regulators, STAT1 and STAT3, respectively. Conversely, knockdown of free fatty acid receptors significantly attenuated the anti-inflammatory role of propionate. Interestingly, propionate recapitulated the blunting of CD4+ TH cell activation in primary cells from obese individuals, extending the role of this metabolite to a disease associated with low-grade inflammation. Together, these data identify a nutrient-load responsive SCFA–G protein–coupled receptor linked pathway to regulate CD4+ TH cell immune responsiveness. Propionate blunts T helper cell responsiveness. [ABSTRACT FROM AUTHOR]

BACKGROUND. Fasting and [NAD.sup.+]-boosting compounds, including [NAD.sup.+] precursor nicotinamide riboside (NR), confer antiinflammatory effects. However, the underlying mechanisms and therapeutic potential are incompletely defined. METHODS. We explored the underlying biology in myeloid cells from healthy volunteers following in vivo placebo or NR administration and subsequently tested the findings in vitro in monocytes extracted from patients with systemic lupus erythematosus (SLE). RESULTS. RNA-Seq of unstimulated and LPS-activated monocytes implicated NR in the regulation of autophagy and type I IFN signaling. In primary monocytes, NR blunted LPS-induced IFN-[beta] production, and genetic or pharmacological disruption of autophagy phenocopied this effect. Given that [NAD.sup.+] is a coenzyme in oxidoreductive reactions, metabolomics was performed and identified that NR increased the inosine level. Inosine supplementation similarly blunted autophagy and IFN-[beta] release. Finally, because SLE exhibits type I IFN dysregulation, we assessed the NR effect on monocytes from patients with SLE and found that NR reduced autophagy and IFN-[beta] release. CONCLUSION. We conclude that NR, in an [NAD.sup.+]-dependent manner and in part via inosine signaling, mediated suppression of autophagy and attenuated type I IFN in myeloid cells, and we identified NR as a potential adjunct for SLE management. TRIAL REGISTRATION. ClinicalTrials.gov registration numbers NCT02812238, NCT00001846, and NCT00001372. FUNDING. This work was supported by the NHLBI and NIAMS Intramural Research divisions., Introduction Caloric restriction, intermittent fasting, time-restricted feeding, and fasting mimetic diets confer immunomodulatory effects, including amelioration of inflammatory diseases (1-6) and blunting of the NLRP3 inflammasome, circulating cytokines, and acute-phase [...]

Aims Prolyl hydroxylation is a post-translational modification that regulates protein stability, turnover, and activity. The proteins that catalyze prolyl hydroxylation belong to the 2-oxoglutarate- and iron-dependent oxygenase family of proteins. 2-oxoglutarate- and iron-dependent oxygenase domain-containing protein 1 (Ogfod1), which hydroxylates a proline in ribosomal protein s23 is a newly described member of this family. The aims of this study were to investigate roles for Ogfod1 in the heart, and in the heart's response to stress. Methods and results We isolated hearts from wild-type (WT) and Ogfod1 knockout (KO) mice and performed quantitative proteomics using tandem mass Tag labelling coupled to liquid chromatography and tandem mass spectrometry (LC-MS/MS) to identify protein changes. Ingenuity pathway analysis identified 'Urate Biosynthesis/Inosine 5′-phosphate Degradation' and 'Purine Nucleotides Degradation II (Aerobic)' as the most significantly enriched pathways. We performed metabolomics analysis and found that both purine and pyrimidine pathways were altered with the purine nucleotide inosine 5′-monophosphate showing a 3.5-fold enrichment in KO hearts (P = 0.011) and the pyrimidine catabolism product beta-alanine showing a 1.7-fold enrichment in KO hearts (P = 0.014). As changes in these pathways have been shown to contribute to cardioprotection, we subjected isolated perfused hearts to ischaemia and reperfusion (I/R). KO hearts showed a 41.4% decrease in infarct size and a 34% improvement in cardiac function compared to WT hearts. This protection was also evident in an in vivo I/R model. Additionally, our data show that treating isolated perfused WT hearts with carnosine, a metabolite of beta-alanine, improved protection in the context of I/R injury, whereas treating KO hearts with carnosine had no impact on recovery of function or infarct size. Conclusions Taken together, these data show that Ogfod1 deletion alters the myocardial proteome and metabolome to confer protection against I/R injury. [ABSTRACT FROM AUTHOR]

BACKGROUNDFasting and NAD+-boosting compounds, including NAD+ precursor nicotinamide riboside (NR), confer antiinflammatory effects. However, the underlying mechanisms and therapeutic potential are incompletely defined.METHODSWe explored the underlying biology in myeloid cells from healthy volunteers following in vivo placebo or NR administration and subsequently tested the findings in vitro in monocytes extracted from patients with systemic lupus erythematosus (SLE).RESULTSRNA-Seq of unstimulated and LPS-activated monocytes implicated NR in the regulation of autophagy and type I IFN signaling. In primary monocytes, NR blunted LPS-induced IFN-β production, and genetic or pharmacological disruption of autophagy phenocopied this effect. Given that NAD+ is a coenzyme in oxidoreductive reactions, metabolomics was performed and identified that NR increased the inosine level. Inosine supplementation similarly blunted autophagy and IFN-β release. Finally, because SLE exhibits type I IFN dysregulation, we assessed the NR effect on monocytes from patients with SLE and found that NR reduced autophagy and IFN-β release.CONCLUSIONWe conclude that NR, in an NAD+-dependent manner and in part via inosine signaling, mediated suppression of autophagy and attenuated type I IFN in myeloid cells, and we identified NR as a potential adjunct for SLE management.TRIAL REGISTRATIONClinicalTrials.gov registration numbers NCT02812238, NCT00001846, and NCT00001372.FUNDINGThis work was supported by the NHLBI and NIAMS Intramural Research divisions. [ABSTRACT FROM AUTHOR]

Mitochondrial adaptations are fundamental to differentiated function and energetic homeostasis in mammalian cells. But the mechanisms that underlie these relationships remain poorly understood. Here, we investigated organ‐specific mitochondrial morphology, connectivity and protein composition in a model of extreme mammalian metabolism, the least shrew (Cryptotis parva). This was achieved through a combination of high‐resolution 3D focused ion beam electron microscopy imaging and tandem mass tag mass spectrometry proteomics. We demonstrate that liver and kidney mitochondrial content are equivalent to the heart, permitting assessment of mitochondrial adaptations in different organs with similar metabolic demand. Muscle mitochondrial networks (cardiac and skeletal) are extensive, with a high incidence of nanotunnels – which collectively support the metabolism of large muscle cells. Mitochondrial networks were not detected in the liver and kidney as individual mitochondria are localized with sites of ATP consumption. This configuration is not observed in striated muscle, likely due to a homogeneous ATPase distribution and the structural requirements of contraction. These results demonstrate distinct, fundamental mitochondrial structural adaptations for similar metabolic demand that are dependent on the topology of energy utilization process in a mammalian model of extreme metabolism. Key points: Least shrews were studied to explore the relationship between metabolic function, mitochondrial morphology and protein content in different tissues.Liver and kidney mitochondrial content and enzymatic activity approaches that of the heart, indicating similar metabolic demand among tissues that contribute to basal and maximum metabolism. This allows an examination of mitochondrial structure and composition in tissues with similar maximum metabolic demands.Mitochondrial networks only occur in striated muscle. In contrast, the liver and kidney maintain individual mitochondria with limited reticulation.Muscle mitochondrial reticulation is the result of dense ATPase activity and cell‐spanning myofibrils which require networking for adequate metabolic support. In contrast, liver and kidney ATPase activity is localized to the endoplasmic reticulum and basolateral membrane, respectively, generating a locally balanced energy conversion and utilization.Mitochondrial morphology is not driven by maximum metabolic demand, but by the cytosolic distribution of energy‐utilizing systems set by the functions of the tissue. [ABSTRACT FROM AUTHOR]