Metabolic stress from a high-fat diet (HFD) impairs antitumor immunity through persistent metabolic rewiring, but its effects and long-term impact on CD8+ T cell metabolism remain unknown. Here, we found that even temporary exposure to a HFD impaired antitumor immunity 10 weeks after reversion to a normal diet. This was due to lasting metabolome changes that included enrichment in phospholipids sensitive to peroxidation and depletion of antioxidants, affecting the survival and function of CD8+ T cells. Under oxidative stress, CD8+ T cells utilized the xanthine salvage pathway to produce guanosine triphosphate, enhancing the amount of tetrahydrobiopterin. Xanthine supplementation reduced lipid peroxidation in tumor-draining lymph nodes and improved antitumor immunity in mice previously on a HFD. Our data indicate that metabolic stress in CD8+ T cells persists long after restoration of a balanced diet, and manifests as vulnerability to ferroptosis, which could be mitigated by replenishing biopterins through the xanthine salvage pathway.

Dynamic temperature gradients exist across the bodies of endothermic animals, from the core to peripheral organ, resulting in the physiological cold environment in superficial regions. Consequently, macrophages distributed throughout the body must be able to adapt not only to thermoneutral conditions but also to colder environments. In fact, it is known that environmental temperature influences macrophage immune responses. However, the thermo-responsive mechanisms of macrophage have been largely unexplored. Here we show that macrophage themselves maintains intracellular temperature under physiological cold condition by increasing proton leak index (defined as mitochondrial proton leak per spare respiratory capacity). We further identified a contribution of ADP/ATP carrier (AAC) to this increase in proton leak index. This cell-autonomous thermogenesis pathway, which does not depend on neural or hormonal inputs, highlights the potential for local and organ-specific temperature regulation. Moreover, cold stress reduced mitochondrial membrane potential, which in turn suppressed the expression of the antimicrobial peptide Resistin-like molecule alpha (RETNLA) and diminished antibacterial properties. Together, these findings suggest that macrophages generate heat whereas compromising antibacterial properties, thereby increasing susceptibility to bacterial infection in physiological cold environment. This adaptation mechanism may underscore the important role of temperature homeostasis in non-adipocyte cells. ### Competing Interest Statement The authors have declared no competing interest. JSPS (Japan Society for the Promotion of Science) KAKENHI (Grant-in-Aid for Scientific Research C), 21K06858, 24K10096, 25K11306 AMED (Japan Agency for Medical Research and Development), JP23gm6510023

Abstract Pregnancy is accompanied by profound endocrine remodeling, yet the mechanisms by which maternal hormonal signals establish long-term tissue homeostasis remain largely unknown. Here we identify maternal progesterone signaling as a developmental cue that establishes lifelong oral homeostasis through a hormone–lipid–microbiome axis. We show that the membrane progesterone receptor mPRδ is selectively expressed in the developing and maternal submandibular glands, where it mediates non-genomic progesterone signaling to promote epithelial differentiation by driving the selective mobilization of docosahexaenoic acid (DHA). Loss of this pathway disrupts salivary gland maturation, reshapes the oral microbial ecosystem through the selective expansion of Pasteurellaceae, and causes local inflammation as well as systemic metabolic dysfunction. Mechanistically, antibiotic treatment abolishes these phenotypes, whereas transfer of the oral microbiota recapitulates disease, demonstrating that developmental defects in the host are translated into long-term pathology through the oral microbiome. Remarkably, maternal—but not adult—DHA supplementation restores salivary gland development and microbial homeostasis and prevents adult disease phenotypes, identifying a critical developmental window during which oral homeostasis is durably established. Collectively, these findings reveal a previously unrecognized maternal endocrine mechanism that establishes lifelong host–microbiome homeostasis and identify developmental programming as a fundamental principle linking maternal physiology to adult health. Abstract Figure

Some major challenges faced in current bone substitutes are infection and poor bone regeneration capacity. Skeletal diseases, the associated postoperative infections, and the risk of bone regeneration failure are increasing because of the increase in the global aging population. We have developed materials for bone regeneration that were based on octacalcium phosphate (OCP), which is a highly biocompatible major inorganic component of immature bones, using the ionic insertion method. Herein, we developed functional OCP blocks by introducing silica and Ag in the OCP crystal structure and evaluated their bone regeneration capacity. Similar to OCPs containing only Ag, Ag-substituted OCP-silica blocks (OCP-silica:Ag blocks) exhibited crucial contact antimicrobial activity against Staphylococcus aureus. The bone regeneration capacity of OCP-silica:Ag blocks implanted into bone defects created in rabbit femurs was comparable with that of OCP-silica blocks, with a remarkably higher bone attachment. In particular, they exhibited a critical cortical bone regeneration, which was not observed when OCP-silica blocks were used. These results reveal that, unlike the Ag phosphate coating on the surface of carbonate apatite introduced in previous studies, the Ag addition to OCP crystals introduces antibacterial properties and enhances the OCP bone regeneration capacity.

Successful pregnancy requires coordinated regulation between the innate and adaptive immune systems. Regulatory T (Treg) cells are essential for establishing maternal immune tolerance to the semi-allogeneic fetus, but the innate immune cells that modulate this process remain poorly defined. Here, we identify CD169+ macrophages in the endometrium as critical regulators of Treg cell recruitment and implantation. These CD169+ macrophages are endometrial localized, exhibit an anti-inflammatory phenotype, and secrete chemokines that attract Treg cells to the endometrium. We also identified CD169+ macrophages in the human endometrium that express chemokines involved in Treg cell recruitment. Our findings identify endometrial CD169+ macrophages as key orchestrators of Treg cell accumulation at the maternal-fetal interface, providing mechanistic insight into implantation and conceptus development.

Interleukin-17-producing γδT cells (γδT17 cells) play a dual role in immune regulation, serving as both protectors in various tissues and orchestrators of inflammatory responses in autoimmune diseases, including experimental autoimmune encephalomyelitis (EAE), a rodent model of multiple sclerosis. However, the ontology and repertoires of encephalitogenic γδT17 cells remain unclear. In this study, we demonstrate that the encephalitogenicity of γδT17 cells is conferred through microfold cell (M cell)-dependent uptake of commensal bacteria in Peyer’s patches. Specifically, CXCR6 hi Vγ6 + Vδ1 + invariant γδT17 cells are activated by specific commensal bacteria such as Lactobacillus spp., which stimulate TCR of CXCR6 hi Vγ6 + Vδ1 + invariant γδT17 cells. During the early stages of EAE, γδT17 cells infiltrate the central nervous system (CNS), initiating a type 17 inflammatory response. Our findings illustrate that Peyer’s patch M cells serve as a critical bridge, linking the pathological association between commensal bacteria and the onset of CNS inflammation.

Pain transmission is considered a unilateral process; however, development of bilateral hyperalgesia, including mirror-image pain (MIP), challenges this notion. The neural basis underlying bilateral hyperalgesia remains unclear. We investigated whether microglial activation within the corpus callosum is associated with interhemispheric propagation of inflammatory responses contributing to MIP. In a photothrombotic reperfusion mouse model, lysophosphatidic acid (LPA) signalling was associated with microglial activation in the contralateral corpus callosum and MIP development. Furthermore, PF8380 or minocycline suppressed bilateral hyperalgesia with MIP, supporting the therapeutic relevance of targeting LPA signalling and microglial activation. Together, these data support a model of an inflammatory circuit involving ischemic-core LPA, callosal microglia, contralateral insular PGE₂ signalling, and contralateral ACC activation that contribute to MIP. Because dysregulated LPA signalling and microglial activation are features of other neuroinflammatory conditions, transcallosal glial crosstalk may also contribute to widespread pain syndromes. Our findings highlight the therapeutic potential of targeting LPA-related pathways.

SGLT2 inhibitors are widely used to treat patients with chronic heart failure, and several studies have shown that the efficacy of SGLT2 inhibitors also extends to acute heart failure. However, the mechanisms remain unknown. Here, using knockout mice and pharmacological approaches, we show that short-term SGLT2 inhibitor treatment activates hypoxia-inducible factor-1α (HIF-1α) signaling in cardiomyocytes, and further pharmacological studies raised the possibility that this effect is mediated by ketone body-derived succinate. One week of Dapagliflozin administration upregulated the expression of HIF-1α target genes, and the effect was abolished in cardiomyocyte-specific HIF-1α knockout mice. Metabolome analysis and enzyme-based assays revealed that, following one week of short-term Dapagliflozin treatment, ketone body levels in the heart increased, leading to an accumulation of succinate, which may act as a signaling metabolite that stabilizes HIF-1α. Administration of pimozide, which is a succinyl-CoA:3-ketoacid CoA transferase (SCOT) inhibitor that inhibits ketone body metabolism, abolished dapagliflozin-elicited activation of HIF-1α signaling. These results, although not conclusive, can be plausibly explained if short-term Dapagliflozin treatment activates HIF-1α signaling in cardiomyocytes via ketone body-derived succinate. Our study raises the possibility that HIF-1α plays a role in the effects of SGLT2 inhibitors and highlights HIF-1α as a speculative target for future studies.

Obesity imprints an epigenetic memory in adipose tissue macrophages (ATMs), allowing proinflammatory traits to persist after weight loss. However, mechanisms by which ATMs sustain efferocytosis and influence adipose tissue mass remain unclear. Here, we demonstrate that aberrant messenger RNA splicing, caused by dysfunction of the CWC22/exon junction complex, limits efferocytosis in macrophages during postobesity weight loss. Multiomics and gene-targeting approaches revealed that 51.9% of the obesity-induced differentially spliced genes in ATMs remained altered after weight loss, identifying persistent splicing alterations as a prominent component of obesity memory, with one-quarter of these changes dependent on CWC22. Scarb1 exon skipping increased scavenger receptor class B type II (SR-BII) expression, promoting the formation of SR-BI/SR-BII heterodimers that were subsequently targeted for endoplasmic reticulum-associated degradation. This reduced surface SR-BI in macrophages, suppressed efferocytosis and inosine release from dead cells, and impaired inosine-induced lipolysis in white adipose tissue. Restoring Scarb1 splicing with an antisense oligonucleotide rescued SR-BI expression, efferocytosis, inosine availability, and fat loss in Cwc22-deficient mice. Immunohistochemical analysis of human adipose tissue specimens revealed predominant nuclear localization of CWC22 in ATMs from lean individuals, whereas this nuclear localization was markedly diminished in ATMs from obese individuals. These findings reveal that aberrant alternative splicing in macrophages underlies resistance to postobesity weight loss and suggest that splicing-targeted therapies may counteract obesity memory.

No established blood markers can preoperatively predict postoperative delirium. Blood concentrations of amino acid catabolites and dipeptides, including those secreted extracellularly during T-lymphocyte activation, were investigated as predictors of postoperative delirium using metabolomic analyses to ascertain whether preoperative blood metabolites could predict postoperative delirium. Eighteen and 24 participants were included in the delirium and non-delirium groups, respectively. Higher preoperative levels of amino acid (tryptophan) catabolites, via the indoleamine 2,3-dioxygenase pathway, were observed in the delirium group and identified as potential predictors of postoperative delirium in this study. The delirium group had preoperatively elevated levels of tryptophan catabolites and only a limited increase postoperatively, suggesting that the tryptophan catabolic pathway may be activated preoperatively in patients at high risk of delirium. Non-targeted metabolomic analysis found a set of preoperatively elevated γ-glutamyl dipeptides as potential predictors of postoperative delirium. In vitro experiments showed that T-cell-receptor stimulation increases tryptophan metabolism and specific γ-glutamyl dipeptide secretion, offering a possible explanation for the increased levels of metabolites in postoperative delirium. This study showed that levels of amino acid metabolites associated with blood immune activity may have the potential to predict postoperative delirium.

Understanding the interactions between various aging processes and the resulting heterogeneity in aging is crucial for promoting healthy aging. Here, we provide evidence that heterogeneity in microbiome and host interactions contributes to diversifying aging phenotypes in sleep, gut integrity, and longevity in Drosophila. Aged flies exhibiting sleep fragmentation preserve gut integrity, accompanied by a shift in microbiota composition, particularly an increase in Acinetobacter junii. A. junii induces sleep fragmentation via its metabolite, urocanic acid, through serotonin receptor-dependent dopamine upregulation. In parallel, A. junii exploits the host response to promote its growth, leading to lifespan extension, which is recapitulated by genetically modified Escherichia coli, suggesting a trade-off between sleep quality and lifespan. Our study demonstrates a systematic mechanism underlying aging heterogeneity, suggesting interventions through bacterial supplements. ### Competing Interest Statement The authors have declared no competing interest.

OBJECTIVE:Hepatic steatosis, the early stage of nonalcoholic fatty liver disease (NAFLD), currently lacks targeted pharmacological treatments. G protein-coupled receptors (GPCRs) in hepatocytes differentially regulate lipid metabolism depending on their coupling profile of G protein subtypes. Unlike Gs, Gi, and Gq signaling, the role of G12 signaling in hepatic steatosis remains elusive. The objective of this study was to investigate the effect of G12 signaling on hepatic steatosis and obesity and its mechanisms. METHODS:We generated mice expressing a G12-coupled designer GPCR in a liver-specific manner. We performed phenotypic analysis in the mice under the condition of fasting (acute hepatic steatosis model) or high-fat diet feeding (chronic hepatic steatosis model). RESULTS:In acute and chronic hepatic steatosis models, chemogenetic activation of hepatic G12 signaling suppressed the progression of hepatic steatosis. The treatment led to an increased triglyceride secretion with little effect on mitochondrial respiratory activity, fatty acid oxidation, de novo lipogenesis, and fatty acid uptake. Furthermore, in a high-fat-diet-induced obesity model, activation of the G12-coupled designer GPCR exerted anti-obesity effects with increased whole-body energy expenditure and fat oxidation. Anti-FGF21 antibody treatment showed that the anti-obesity effects of the hepatic G12D activation relied in part on the hepatokine FGF21. CONCLUSIONS:Our findings indicate that the activation of G12 signaling in the liver has the potential to prevent hepatic steatosis and obesity. This discovery provides a strong rationale for the development of drugs targeting G12-coupled GPCRs expressed in the liver.

Taurine, the most abundant sulfonic amino acid in humans is largely obtained from diets rich in animal proteins. However, taurine is dietary non-essential because it can be synthesized from cysteine by activation of transsulfuration pathway (TSP) when food consumption is low or if the diet is predominantly plant based. The decline of taurine was proposed as the driver of aging through an undefined mechanism. Here, we found that mild food restriction in humans for one year that resulted in 14% reduction of calorie intake elevated the hypotaurine and taurine concentration in adipose tissue. Therefore, we investigated whether elevated taurine mimics caloric-restriction's beneficial effects on inflammation, a key mechanism of aging. Interestingly, aging increased the circulating and tissue concentrations of taurine suggesting that elevated taurine may serve as a hormetic stress response metabolite that regulates mechanism of age-related inflammation. The elevated taurine protected mice against mortality from sepsis and inhibited inflammasome-driven inflammation and gasdermin-D (GSDMD) mediated pyroptosis. Mechanistically, 'danger signals' including hypotonicity that activate NLRP3-inflammasome, caused upstream taurine efflux from macrophages, which triggered potassium (K+) release and downstream canonical NLRP3 inflammasome assembly, caspase-1 activation, GSDMD cleavage and IL-1β and IL-18 secretion that was reversed by taurine restoration. Notably, taurine does not efflux from GSDMD pore and inhibited IL-1β from macrophages independently of known transporters SLC6A6 and SLC36A1. Increased taurine in old mice promotes healthspan by inducing anti-inflammatory pathways previously linked to youthfulness. These findings demonstrate that taurine is an upstream metabolic sensor of cellular perturbations that control NLRP3 inflammasome and lowers age-related inflammation.

Abstract Background Delirium is a notable risk factor for cognitive dysfunction and poor prognosis. Despite its importance, there is currently no established blood marker that can predict postoperative delirium in the preoperative period. Aims & Objectives We aimed to examine that water-soluble metabolites, lipids, and cytokines in peripheral blood could uniquely classify postoperative delirium. In addition, we investigated whether changes in neuroinflammation-related and water-soluble metabolites in the indoleamine 2,3-dioxygenase (IDO) pathway could predict postoperative delirium. Method We designed a prospective cohort study of postoperative delirium and received approval from the Keio University School of Medicine Ethics Committee in December 2017. We used a comprehensive metabolomics and cytokine panel analysis involving 18 subjects in the delirium group and 24 subjects in the non-delirium group to determine whether preoperative blood metabolites, lipids, and cytokines could predict postoperative delirium. We also performed non-targeted metabolomics to investigate unanticipated small molecular weight metabolites in addition to IDO pathway metabolites and their correlations with cytokines indicative of an activated immune state. In addition, we conducted an in vitro experiment to test secretion with T-cell receptor stimulation on T cells. Results & Discussion We found that preoperative levels of amino acid catabolites, especially tryptophan catabolites produced via the IDO pathway, were higher in the delirium group than in the non-delirium group. These catabolites were validated as reliable predictors of postoperative delirium. Interestingly, the delirium group had elevated levels of tryptophan catabolites even before surgery, but only a limited increase in these levels was observed postoperatively. This suggests that the tryptophan catabolic pathway may be activated preoperatively in patients at high risk for developing delirium. In addition, our non-targeted metabolomic analysis identified a set of preoperatively elevated gamma-glutamyl dipeptides as significant discriminators of postoperative delirium. In vitro experiments showed that T- cell receptor stimulation resulted in increased tryptophan metabolism and specific gamma-glutamyl dipeptide secretion, which may explain increased metabolic byproducts in postoperative delirium. Conclusion Our study highlights the potential of blood concentrations of amino acid catabolites and dipeptides, including those secreted extracellularly upon T-cell activation, as reliable predictors of postoperative delirium.

The pathogenesis of metabolic dysfunction-associated steatohepatitis (MASH) is not well understood, and effective antifibrotic therapies are still lacking. Gut-liver interactions play a critical role in MASH progression. Fecal analysis of ten MASH patients and twelve healthy donors revealed a significant enrichment of Enterococcus faecalis in the MASH patients. Oral gavage of E. faecalis exacerbated liver fibrosis in a mouse model of MASH induced by a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD). Recombinant W27 (rW27) IgA, a mouse-derived monoclonal antibody, strongly binds to E. faecalis and potently inhibits its growth in vitro. Furthermore, the oral administration of rW27 IgA to E. faecalis-colonized MASH mice significantly reduced liver fibrosis by suppressing E. faecaliscolonization and restoring the gut microbiota. These results suggest a new therapeutic approach for MASH that involves the oral administration of rW27 IgA to inhibits the colonization of pathogenic E. faecalis, restores gut microbiota, and attenuates liver fibrosis.

Caloric restriction and methionine restriction-driven enhanced lifespan and healthspan induces 'browning' of white adipose tissue, a metabolic response that increases heat production to defend core body temperature. However, how specific dietary amino acids control adipose thermogenesis is unknown. Here, we identified that weight loss induced by caloric restriction in humans reduces thiol-containing sulfur amino acid cysteine in white adipose tissue. Systemic cysteine depletion in mice causes lethal weight loss with increased fat utilization and browning of adipocytes that is rescued upon restoration of cysteine in diet. Mechanistically, cysteine-restriction-induced adipose browning and weight loss requires sympathetic nervous system-derived noradrenaline signalling via β3-adrenergic-receptors that is independent of FGF21 and UCP1. In obese mice, cysteine deprivation induced rapid adipose browning, increased energy expenditure leading to 30% weight loss and reversed metabolic inflammation. These findings establish that cysteine is essential for organismal metabolism as removal of cysteine in the host triggers adipose browning and rapid weight loss.

Menstrual pain affects women’s quality of life and productivity, yet objective molecular markers for its severity have not been established owing to the variability in blood levels and chemical properties of potential markers such as plasma steroid hormones, lipid mediators, and hydrophilic metabolites. To address this, we conducted a metabolomics study using five analytical methods to identify biomarkers that differentiate menstrual pain severity. This study included 20 women, divided into mild (N = 12) and severe (N = 8) pain groups based on their numerical pain rating scale. We developed pretreatment procedures that allowed all analyses from only 100 µL of finger-prick blood collected across the menstrual cycle. Among the 692 quantified metabolites, branched-chain amino acids and specific phosphatidylinositol (PI), especially PI(36:2), were identified as potential biomarkers. Furthermore, the ratio of PI(36:2) to each BCAA or total BCAA effectively discriminated between the severity levels of menstrual pain. These ratios correlated positively with NPRS, indicating high accuracy in pain assessment. This study highlights the potential of small molecular markers to objectively assess menstrual pain severity, aiding evidence-based support and intervention.