Journal of Cachexia, Sarcopenia and Muscle

BackgroundCancer-associated cachexia is characterized by progressive loss of skeletal muscle and adipose tissue driven by systemic inflammation and metabolic dysregulation. AMP-activated protein kinase (AMPK) is a central regulator of energy homeostasis, but its role in cachexia and its therapeutic potential remains incompletely defined. We investigated AMPK signaling during cachexia and whether pharmacological AMPK activation alone or combined with ghrelin could ameliorate disease manifestations. MethodsCachexia was induced in male C57BL/6 mice by Lewis lung carcinoma (LLC) implantation. Additional models included fibrosarcoma (CHX and MN/MCA1) and chronic lymphocytic choriomeningitis virus (LCMV) infection. AMPK was activated using AICAR and BC1618 (AB), alone or combined with ghrelin (AB+G). Metabolic, inflammatory, and functional outcomes were assessed in hypothalamus, skeletal muscle, adipose tissue, and serum. ResultsLLC-bearing mice developed cachexia characterized by reduced body weight, lean and fat mass, hypophagia, and elevated circulating IL-6 and corticosterone. Cachectic LLC mice displayed increased Il6 and Il1{beta} expression in hypothalamus, skeletal muscle, and white adipose tissue (WAT). Furthermore, AMPK activation failed to increase in hypothalamus or peripheral tissues despite profound energy deficit. A similar defect in AMPK responsiveness was observed in CHX and LCMV models, indicating a conserved feature of cachexia. AB treatment in LLC mice reduced circulating IL-6 and corticosterone levels and decreased skeletal muscle atrogene expression and IL-6/STAT3 signaling, partially preserving muscle mass, fiber size, and grip strength. However, food intake remained low, and WAT was largely unresponsive, maintaining elevated Il6 expression and tissue loss. Ghrelin alone increased food intake in LLC mice but did not ameliorate the cachectic phenotype. In contrast, AB+G restored food intake and prevented loss of lean and fat mass. LLC AB+G mice exhibited reduced hypothalamic Il6 and serotonin transporter (Slc6a4) expression, normalized adipocyte morphology and serum leptin levels, decreased adipose Il6 and Atgl expression and reduced WAT sympathetic innervation. AB+G further lowered circulating corticosterone levels, and provided greater protection against muscle wasting, with increased Pgc1 expression and improved muscle function. Neither intervention affected tumor growth or tumor inflammatory gene expression. ConclusionsCancer cachexia is associated with a central and peripheral failure to appropriately activate AMPK signaling in response to the energetic stress imposed by cachexia. Combined AMPK activation and ghrelin administration exerted complementary effects on energy homeostasis, inflammation, and tissue wasting, resulting in greater protection against cachexia than either intervention alone. These findings support combined AMPK-ghrelin targeting as a promising therapeutic strategy for cancer cachexia.

BackgroundAberrant NAD+ metabolism has been implicated in the pathogenesis of cancer cachexia, highlighting this pathway as a potential therapeutic target to mitigate skeletal muscle wasting. However, it remains unclear whether chemotherapeutic agents contribute to the onset of cachexia by disrupting NAD+ metabolism. Here, we investigated the effects of commonly used chemotherapy regimens on NAD+ metabolism in skeletal muscle and liver of healthy mice. MethodsHealthy mice were treated with either 2-week regimens of folfiri or cisplatin, or 5-week regimens of folfiri or folfox, with vehicle-treated mice serving as controls. Cachexia-related outcomes were assessed, while skeletal muscle and liver tissues were analyzed for NAD metabolites and markers of NAD+ metabolism. Given the consistent downregulation of the NAD+ biosynthetic enzyme Nrk2 in cachectic chemotherapy-treated mice, we examined skeletal muscle Nrk2/NRK2 expression across published murine and human cachexia datasets, and in additional models of muscle wasting and hypertrophy. ResultsNAD+ loss was observed in atrophic muscle following administration of cisplatin (2-week treatment; -14% vs controls, p=0.047) and folfiri (5-week treatment; -18%, p=0.069). In contrast, muscle NAD+ levels were preserved in non-atrophic groups (2-week folfiri and 5-week folfox). Muscle Nrk2 was the most responsive NAD+ biosynthetic enzyme, showing consistent downregulation across chemotherapy models with ongoing or developing muscle loss: cisplatin (-93%, p<0.001), folfiri (-84%, p<0.001) and folfox (-92%, p<0.001). In the liver, NAD+ levels declined after prolonged 5-week folfiri (-20%, p=0.013) and folfox (-15%, p=0.043) treatments. These changes were accompanied by distinct alterations in NAD+ biosynthesis pathways, indicating treatment-specific reorganization of hepatic NAD+ metabolism. Cross-study analyses revealed early and consistent skeletal muscle Nrk2 downregulation across multiple murine cachexia models and human inactivity studies, whereas cachexia-targeted interventions in rodents and resistance training in humans increased its expression. ConclusionsThese findings demonstrate that chemotherapy distrupts tissue NAD+ metabolism, with skeletal muscle NAD+ loss accompanying muscle atrophy and hepatic NAD+ levels declining after prolonged treatment. The early and robust responsiveness of muscle Nrk2 expression to changes in muscle mass underscores its potential as a dynamic indicator for predicting treatment-induced changes in muscle mass. Together, these results provide new molecular insight into the metabolic basis of chemotherapy-induced muscle wasting and support further investigation of NAD+-targeted strategies in this context.

Regeneration of skeletal muscle preserves muscle mass and function, which decline with age. Here, we sought to identify long noncoding (lnc)RNAs involved in skeletal muscle myogenesis and potentially relevant to muscle aging. Cross-sectional analysis of skeletal muscle transcriptomes from healthy 22-through 89-year-old individuals revealed lncRNA LANCL1-AS1 among the top declining transcripts. Conversely, LANCL1-AS1 increased robustly during skeletal myogenesis and promoted myogenic differentiation in culture. Affinity pulldown by ChIRP followed by mass spectrometry revealed that LANCL1-AS1 associated with the mitochondrial protein LRPPRC, enhancing the formation of the chaperone complex LRPPRC-SLIRP, which maintains longer poly(A) tails of mitochondrial (mt-)mRNAs and stabilizes mt-mRNAs. Importantly, while myoblasts from old rhesus monkey muscle expressed lower levels of LANCL1-AS1 and mt-mRNAs, and displayed lower mitochondrial activity than young monkey myoblasts, overexpressing LANCL1-AS1 in old myoblasts restored mitochondrial activity and myogenesis. We propose that the age-associated reduction in LANCL1-AS1 contributes to impaired mitochondrial function and reduced myogenic capacity in aging skeletal muscle.

Skeletal muscle homeostasis depends on the coordinated regulation of protein turnover and mitochondrial quality control; however, the molecular mechanisms linking these processes remain unclear. In this study, we examined the physiological role of leucine aminopeptidase 3 (LAP3), a post-proteolytic aminopeptidase, using constitutive LAP3-deficient mice. LAP3 deficiency preferentially affected skeletal muscle, causing reduced muscle mass and mitochondrial enlargement in both sexes. Female LAP3-deficient mice also showed reduced myofiber size, impaired endurance capacity, increased energy expenditure, elevated lipid oxidation, and lipid droplet accumulation adjacent to the mitochondria. Proteomic analyses revealed remodeling of pathways related to lipid metabolism and protein homeostasis. Consistent with these findings, LAP3 deficiency increased the expression of Pink1 and Tax1bp1 and promoted the accumulation of ubiquitinated proteins, suggesting alterations in mitochondrial quality control and proteostatic regulation. In cultured myogenic cells, LAP3 localized to mitochondrial fractions, and both LAP3 knockdown and overexpression altered mitochondrial morphology. Taken together, these results identify LAP3 as a regulator of skeletal muscle homeostasis and support a role for LAP3 in linking intracellular peptide turnover to mitochondrial homeostasis, with female skeletal muscle showing greater susceptibility to LAP3 deficiency.

Glucagon-like peptide 1 receptor agonists (GLP-1RAs) have become defining therapies in the management of type 2 diabetes and obesity. Despite recent interest in the effects of GLP-1RA therapy on skeletal muscle, their influence on muscle repair after injury remains largely untested. Because GLP-1RA use is common in populations at heightened risk for diminished regenerative capacity, a critical unanswered question is whether GLP-1R agonism supports muscle regeneration or alters the normal course of recovery after injury. Using intramuscular glycerol injection as an adipogenic injury model, we assessed whether semaglutide, a widely prescribed GLP-1RA, alters the balance between myogenesis and adipogenesis during regeneration. Surprisingly, semaglutide treatment markedly increased the formation of intramuscular adipose tissue (IMAT) and inhibited the growth of regenerated fibers. These effects were injury-dependent, as uninjured muscle showed no detectable differences in IMAT or myofiber size. Together, these findings identify a previously underappreciated context in which GLP-1RA therapy may adversely affect muscle quality.

Background & aims: Autophagy activation is a promising strategy to counteract age-related cellular dysfunction. While preclinical studies suggest dietary protein restriction can induce autophagy via mTORC1 inhibition, direct human evidence using dynamic, flux-based measurements remains limited. The aim of this study was to determine whether a low protein diet could modulate autophagic flux in humans. Methods: We conducted a randomized crossover trial in which 74 healthy adults were randomized to receive two 4-week interventions of either average-protein (20% energy) or reduced-protein (10% energy) diets prescribed to maintain calculated energy balance, separated by a 4-week washout period. The primary outcome was autophagic flux measured in whole blood using a validated assay that preserves PBMCs in their physiological environment during lysosomal inhibition. Secondary outcomes included metabolic markers, body composition, and self-reported health metrics. Results: Sixty-three participants completed both interventions (mean {+/-} SD age 29.5 {+/-} 7.2 yrs; BMI 24.0 {+/-} 3.2 kg/m2). Reducing protein intake did not alter autophagic flux (adjusted mean difference: -8.46 ng LC3B-II/mg protein/h; 95% CI: -24.06 to 7.14; p = 0.28). Metabolomic profiling confirmed effective dietary separation, with lower circulating urea following reduced protein intake. Small differences in body weight and muscle mass were observed, while fat mass was unaffected. Fasting glucose, insulin, lipids, blood pressure, and quality of life did not differ between the two diets. Conclusions: Moderate protein restriction does not increase basal autophagy in circulating immune cells of healthy adults, suggesting protein reduction alone, without caloric deficit, may be insufficient to activate autophagy in human blood.

Laminin-2 (gene: LAMA2) is a key protein in the basement membrane of muscle and Schwann cells. A complete lack of this protein results in LAMA2-related congenital muscular dystrophy (LAMA2-RD), a severe muscle disease characterized by progressive muscle weakness, respiratory insufficiency, failure to thrive and shortened life span. One key signature of this disease is early onset of fibrosis coupled with poor muscle growth. We previously showed that TGF-{beta} and its activator, integrin-V, are elevated in dystrophic fibers of DyW mice, a mouse model of LAMA2- RD. Other than activating TGF-{beta}, integrin-V is also known to facilitate the transdifferentiation of various cell types to myofibroblasts. In this study we present evidence for transcriptional dysregulation of genes driving myofibroblast transdifferentiation and extracellular matrix (ECM) remodelling during the early development of DyW mice that is also reflected in muscle biopsies from young LAMA2-RD patients. We hypothesize that the early ECM remodelling, seen in both DyW mice and LAMA2-RD children, may explain the congenital onset of fibrosis with poor muscle growth seen in the disease.

IntroductionThe quality of preclinical studies for rare diseases, such as Duchenne muscular dystrophy (DMD), relies on the availability of comprehensive natural disease history data. In addition to the classic BL10-mdx mouse, in recent years, the D2-mdx model has increasingly been used as an alternative model due to its reportedly more severely impaired phenotype. To improve our understanding of disease progression in these two DMD models, we conducted a comprehensive natural history study. Materials and MethodsThis involved a cross-sectional analysis of key in vivo and ex vivo outcome measures performed in two independent laboratories, using the same study setup in compliance with TREAT-NMD Standard Operating Procedures (SOPs), while also taking advantage of site-specific expertise. Globally, largely comparable results were obtained across the two study sites. ResultsBody composition showed pronounced differences between the strains, with BL10-mdx mice displaying a hypertrophic and D2-mdx mice displaying an atrophic phenotype. Dystrophic mice of each strain exhibited significant alterations of disease-relevant indices related to muscle functionality and integrity, mostly worsening with age, in comparison to their wildtypes. Cardiac function was affected earlier and more severely in D2-mdx mice. DiscussionNotably, for some parameters, genetic-background related differences were observed, emphasizing the need to include control groups with matching genetic backgrounds in experimental designs. ConclusionsCollectively, our natural history study provides benchmark data for these two mdx mouse strains to guide model selection for preclinical DMD studies, allowing accurate data interpretation. HighlightsO_LIDistinct body composition phenotypes: BL10-mdx mice exhibit pseudohypertrophy while D2-mdx mice display pronounced atrophy. C_LIO_LIEarlier cardiac dysfunction in D2-mdx: D2-mdx mice develop reduced ejection fraction and stroke volume from 28 weeks, while BL10-mdx only at 52 weeks. C_LIO_LIGenetic background-dependent variations: Intrinsic deficits in wildtype D2 mice demonstrate that genetic background influences outcome measures independent of dystrophic pathology. C_LIO_LIComparable ex vivo muscle physiology: Despite divergent in vivo phenotypes, isolated muscle contractile parameters show similar impairment in both dystrophic models. C_LIO_LIMulti-site standardized validation: Cross-sectional study at two independent laboratories following harmonized TREAT-NMD Standard Operating Procedures. C_LI

The neuromuscular junction (NMJ) is a specialised synapse between motor neurons and skeletal muscle, and its progressive deterioration contributes to age-related and metabolic disease-associated declines in muscle function. Advanced glycation end-products (AGEs) accumulate in tissues during ageing, diabetes, and chronic metabolic dysfunction and have been implicated in neuromuscular degeneration, yet their effects on the intact NMJ have not previously been examined in a human model system. This study employed a fully human, serum-free, and neural growth factor-free NMJ co-culture system, combining neural progenitor cells with immortalised human myoblasts derived from an 83-year-old donor, to investigate the effects of AGE exposure on neuromuscular integrity across structural, metabolic, functional, and secretory outcomes. AGE exposure induced significant reductions in motor neuron axonal length, myotube remodelling with centralised nuclear positioning, mitochondrial membrane depolarisation, elevated mitochondrial superoxide production, mitochondrial uncoupling, and reductions in spontaneous contraction intensity and frequency. Neurotrophic and myogenic growth factor signalling was significantly downregulated in AGE-treated co-cultures. These findings identify the NMJ as a sensitive target of glycation stress and establish this fully human co-culture platform as a physiologically relevant model for investigating glycation-related neuromuscular pathology and evaluating candidate therapeutic interventions.

Neuromuscular contractures arising from neonatal brachial plexus injuries (NBPI) are highly disabling and currently incurable. We previously showed that contractures involve impaired longitudinal growth of denervated muscles, a defect mediated through myostatin (MSTN) signaling, a potent negative regulator of muscle size. However, MSTN-mediated contractures occur independent of canonical signaling pathways, including SMAD 2/3 and AKT/mTOR. Through a mouse model of NBPI, our present study extended these findings by revealing pharmacologic inhibition of JNK signaling, a noncanonical pathway downstream of MSTN, partially rescues contractures without restoring muscle length. Rather, JNK activation upregulates myofiber expression of the target gene Lmna, which encodes the nuclear envelope proteins Lamin A and Lamin C that are vital for nuclear stability, resulting in pervasive myonuclear displacement. These results suggest that other factors contribute to contracture pathology beyond deficits in longitudinal muscle growth. Further, while JNK inhibition does not restore length of denervated muscles, it impedes size and mass of normally innervated neonatal muscles, suggesting a requirement of JNK signaling for neonatal muscle growth. Our collective findings thereby establish new mechanistic insights into the molecular basis of aberrant muscle growth and neuromuscular contracture formation, potentially leading to novel targets for muscle restorative strategies and medical contracture prevention.

The endoplasmic reticulum (ER) and its muscle-specialized form, the sarcoplasmic reticulum (SR), are crucial organelles in muscle cells, involved notably in protein synthesis, calcium regulation and muscle contraction. A well-known process involved in ER remodeling and homeostasis is ER-phagy, also called reticulophagy, a selective form of autophagic process in which ER-phagy receptors mediate the delivery of ER portions to lysosomes for degradation. SH3KBP1 is an adaptor protein involved in membrane trafficking. Recently, it was shown to control ER morphology and SR formation in striated skeletal muscle. In this study, we demonstrate that SH3KBP1 can bind to LC3B and CKAP4 proteins, bridging ER to autophagosome membranes, and is degraded by autophagy, in developing muscle fibers. Moreover, SH3KBP1 down-regulation impacts basal autophagy efficiency and ER-phagy stimulation; it also impairs the turnover of numerous ER-resident proteins. Our work highlights a new role for SH3KBP1 as a soluble ER-phagy receptor in striated skeletal muscle.

Human skeletal muscle is the principal site of insulin-stimulated glucose disposal and a major mediator of exercise-induced metabolic benefits, yet human models that preserve metabolic and exercise responsiveness remain limited. We generated primary human skeletal muscle organoids from donor-derived CD56+ myoblasts using a collagen-based extracellular matrix and serum-free IGF1-guided differentiation. The organoids formed aligned contractile tissues containing oxidative and glycolytic fiber type-like myotubes, displayed enhanced mitochondrial respiration, insulin-stimulated glucose uptake, and reproducible force generation. Electrical pulse stimulation induced AMPK activation, increased glucose utilization and lactate production, and upregulated canonical exercise-responsive genes including NR4A3 and PPARGC1A. Notably, transcriptional responses to in vitro exercise overlapped with acute exercise responses observed in skeletal muscle biopsies from the same donors. The organoids further detected functional impairments of skeletal muscle performance induced by TGF-{beta}1 and metformin and increased speed generation by testosterone treatment. These findings establish a donor-specific human skeletal muscle platform that recapitulates key features of insulin action and exercise adaptation and may enable mechanistic studies of skeletal muscle metabolism, exercise responsiveness, and therapeutic interventions relevant to diabetes. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=148 SRC="FIGDIR/small/735246v1_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@2ea1c9org.highwire.dtl.DTLVardef@17fa8c1org.highwire.dtl.DTLVardef@2045d5org.highwire.dtl.DTLVardef@c8b059_HPS_FORMAT_FIGEXP M_FIG C_FIG Article highlightsWe generated primary human skeletal muscle organoids under serum-free IGF1-guided conditions to reproduce key metabolic and exercise-responsive features of skeletal muscle. The organoids were insulin-responsive, displayed enhanced mitochondrial function and force-generating contractility, reproduced hallmark molecular and metabolic responses to exercise, overlapping with exercise responses observed in the same donors in vivo. The organoids were suitable to detect functional alterations after treatment with endogenous hormones and cytokines and diabetes medication This platform provides a human donor-specific system for studying skeletal muscle mechanisms underlying insulin sensitivity, exercise benefits, and therapeutic responses relevant to diabetes and metabolic disease.

Objectives: To develop and validate a disease-specific patient-reported outcome (PRO) measure for spinal and bulbar muscular atrophy (SBMA). Methods: A three-stage sequential design was adopted. Items were generated through qualitative interviews with patients with SBMA and expert review, refined using quantitative analyses, and evaluated for reliability and validity in independent cohorts from Japan and the United States. Results: Interviews with 12 patients generated 234 candidate items, which were refined into a final 31-item SBMAPRO comprising five domains based on an online survey of 106 patients. Internal consistency across domains ranged from Cronbach's alpha values of 0.651 to 0.901. In the Japanese cohort, test-retest reliability yielded intraclass correlation coefficients of 0.941 for physical function, 0.877 for mental health, and 0.858 for social function. Construct validity was examined through correlations with disease-specific functional measurements and the 36-Item Short Form Survey (SF-36). The SBMAPRO correlated with the SBMA Functional Rating Scale (r = -0.826, p <0.001) and with the SF-36 mental health (r = -0.693, p <0.001) and social functioning (r = -0.617, p <0.001) domains. In subscale analyses, the SBMAPRO social domain was associated with trunk-lower limb-related functional impairment (r = -0.587, p < 0.001). Similar patterns were observed in the American cohort. Conclusion: The SBMAPRO demonstrated reliability and validity in Japanese and American cohorts. Associations between mental and social domains and trunk-lower limb dysfunction suggest that mobility impairment may contribute to psychological burden and restricted social participation in SBMA, indicating that this disease-specific PRO may complement clinician-rated measures.

Regular exercise induces adaptations in skeletal muscle and other organ systems to improve physical performance and overall health. Exercise results in phosphorylation of 5 AMP-activated protein kinase (AMPK) at threonine 172 (T172) of the 2 subunit; however, the role of this activation in cellular and functional adaptations has not been elucidated. To this end, we subjected non-activatable Ampk2(T172A) knock-in (KI) adult mice and wild-type (WT) littermates to 4 weeks of voluntary wheel running (VWR). Exercise training led to significant improvements in endurance capacity, maximal oxygen consumption ([Formula]O2max), and glucose tolerance, as well as skeletal muscle IIb-to-IIa fiber type shift in both WT and KI mice. Contrastingly, VWR resulted in increased mitochondrial OxPhos protein expression, mitochondrial volume density, and capillary density in skeletal muscle of WT but not KI mice. Exercise-induced improvements of mitochondrial respiration and conductance revealed by high-resolution respirometry of isolated mitochondria were blunted in KI mice. Therefore, for the first time, we reveal that AMPK2 T172 activation is required for exercise training-induced mitochondrial biogenesis, improvement of mitochondrial respiratory function, and angiogenesis in skeletal muscle, but that these adaptations are not solely responsible for improved [Formula]O2max and exercise endurance capacity. Significance StatementExercise is the most effective lifestyle intervention for promoting health and preventing chronic diseases through adaptive changes in skeletal muscle and many other tissues/organs. AMPK is an energy sensor and signaling regulator for exercise-induced skeletal muscle adaptation, yet its functional role and the impact on exercise capacity have been studied in mouse genetic models wherein protein stoichiometry is disrupted. Using non-activatable Ampk2(T172A) knock-in mice, we ascertained that AMPK2 activation via T172 phosphorylation is required for endurance training-induced mitochondrial and angiogenic adaptations in skeletal muscle. Importantly, these adaptations are not required for improved exercise capacity, challenging the prevailing concept that increased mitochondrial content and function and microvasculature are the sole driving factors for the performance gains with endurance training.

Abstract Introduction: The optimal examined lymph node (ELN) count after resection for pancreatic body/tail ductal adenocarcinoma (PDAC) remains uncertain. Guidelines recommend 12-15 nodes, but the value of higher thresholds is unclear. Method: SEER patients with pancreatic body/tail PDAC undergoing resection from 2000 to 2020 were analysed. Survival-anchored ELN thresholds were assessed using log-rank cut-point search, segmented Cox analysis, adjusted restricted cubic splines, and overlap-weighted restricted mean survival time (OW-RMST). A structured synthesis of 17 studies compared threshold attainment after conventional distal pancreatectomy (DP), radical antegrade modular pancreatosplenectomy (RAMPS), and posterior/artery-first approaches. Results: Among 5107 patients, 3630 deaths occurred (71.1%). Log-rank analysis identified ELN = 12 as the optimal binary cut-point; segmented Cox analysis identified ELN = 21 as a change point (bootstrap 95% CI 6.0-35.0). Adjusted splines showed a nonlinear inverse association between ELN and mortality, with attenuation beyond approximately 21 nodes. Each 5-node increase in ELN was associated with lower mortality (HR 0.964, 95% CI 0.949-0.980; P < 0.001). At 60 months, OW-RMST gains for ELN >= 12, >= 14, and >= 21 were 2.59, 2.31, and 2.60 months. Estimated probabilities of achieving ELN >= 21 were 16.5% after conventional DP, 40.0% after RAMPS, and 82.7% after posterior/artery-first approaches, with lowest certainty for the latter. Conclusion: ELN >= 12 is a minimum quality benchmark after resection for pancreatic body/tail PDAC, whereas approximately 21 nodes may be a higher-yield target. RAMPS may improve target attainment, but survival superiority remains unproven.

Abstract Background: The influence of taurine on biological ageing remains unclear, particularly whether it acts as a causal driver or a functional biomarker. We aimed to disentangle the distinct roles of plasma taurine relative abundance, dietary taurine supply, and genetic metabolic capacity on all-cause mortality and unhealthy ageing. Methods: This prospective study used data from the Korean Genome and Epidemiology Study (2001~2022). A subcohort of 2,321 participants (mean age 56.5 years; 51.4% female) with complete metabolomic, dietary, and genomic data was analyzed. Three independent pathways were evaluated: (1) plasma taurine/total amino acid (AA) ratio, (2) dietary taurine to protein ratio, and (3) a weighted genetic risk score (GRS) from 21 SNPs in taurine biosynthesis and transport genes. Primary outcomes were all-cause mortality and unhealthy ageing (Physiological Healthy Ageing Index [PHAI] score [&le;] 25th percentile). Results: A higher plasma taurine/total AA ratio was consistently associated with improved ageing outcomes. Participants in the highest quartile showed 29% lower all-cause mortality (Hazard Ratio [HR], 0.71; 95% Confidence Interval [CI], 0.52-0.98; P for trend = .04) and lower risk of PHAI-based unhealthy ageing (HR, 0.77; 95% CI, 0.59-1.00; P for trend = .04) versus the lowest quartile. Dietary taurine-to-protein ratio was not associated with mortality (P for trend = .70), nor was the GRS (P for trend = .74). Conclusions: The protective association of taurine was linked to its relative abundance within the systemic amino acid pool, rather than dietary intake or genetic predisposition, supporting taurine as a functional biomarker of metabolic efficiency rather than a deterministic causal driver of ageing.

Background: Early detection of pancreatic ductal adenocarcinoma (PDAC) is critical. While faecal elastase-1 (FE-1) is a standard clinical marker for pancreatic function, its diagnostic accuracy for malignancy is limited. We sought to identify plasma metabolites that enhance FE-1 performance in symptomatic "at-risk" patients. Methods: Using the DEPEND cohort (CRUK C45617/A29908), plasma metabolomics was performed on patients with resectable PDAC (n=23) and healthy volunteers (n=24). Predictive modelling included feature selection and cross-validation, with further validation in an independent external cohort. Results: Citrulline was identified as significantly depleted in PDAC patients across discovery and validation cohorts. In isolation, Citrulline achieved an AUC of 0.86 (internal) and 0.88 (external validation). Standalone FE-1 demonstrated an AUC of 0.67. However, combining Citrulline and FE-1 significantly improved diagnostic performance, achieving a combined AUC of 0.96. Stratification revealed distinct metabolomic signatures associated with poorly differentiated tumours, suggesting a link to histological grade. Conclusions: Integrating Citrulline with FE-1 testing substantially improves PDAC detection in symptomatic patients. This non-invasive panel offers high diagnostic potential, though prospective validation is required to establish clinical cut-offs for routine practice.

Abstract Background: Frailty reflects reduced physiological resilience and increased vulnerability to stressors, functioning as a key biological marker of ageing. Yet, the molecular and causal mechanisms linking frailty to chronic inflammatory conditions remain unclear. Methods: We integrate Mendelian randomisation (MR), pairwise genome-wide association (PW-GWAS), and epigenetic-protein prediction to dissect bidirectional biological pathways between frailty, chronic pain (CP), and rheumatoid arthritis (RA). Results: Across nine genetically defined frailty phenotypes - six domain-specific factors, a general frailty factor (GF), and two cumulative indices (Frailty Index - FI, Fried Frailty Score - FFS) - MR revealed widespread causal effects of CP and RA on frailty. Genetic liability to higher chronic pain robustly increased frailty severity across the cumulative frailty measures (FI and FFS) and the disability-related frailty domain (F6), with the strongest effect observed for the Frailty Index ({beta} = 0.70, p = 7.9 x 10-52), while cumulative frailty also elevated pain risk ({beta} = 0.37, p = 2.6 x 10-13), supporting a reciprocal feedback model. RA exerted more selective effects, increasing cumulative frailty (FI and FFS) and disability-related frailty (F6), whereas the general frailty factor increased RA susceptibility (OR = 4.59, p = 9.5 x 10-8). Notably, the multimorbidity-related frailty domain showed an inverse effect on RA risk (OR = 0.65, p = 0.0078), suggesting immune adaptation or exhaustion within advanced frailty states. PW-GWAS and fine-mapping revealed shared causal loci linking inflammation, metabolism, and neurostructural pathways - SLC39A8, NLGN1, IL2RA, ERBB3, and MAGI3 - highlighting neuroimmune and synaptic processes as convergent ageing pathways. Epigenetic-proteomic analyses further identified two opposing axes: inflammatory and complement proteins (CRP, C5, CCL18, STC1) positively associated with frailty, versus neuronal adhesion and extracellular matrix (ECM) proteins (NCAM1, CNTN4, NTRK3, ADAMTS13) conferring resilience. Conclusion: Together, these findings redefine frailty as a biologically dynamic interface between inflammation and structural maintenance, where opposing molecular pathways shape vulnerability and resilience. This integrative framework highlights frailty as both a biomarker and potential intervention target, linking inflammatory dysregulation to modifiable trajectories of functional ageing.

Background: Recreational physical activity has been shown to improve survival among colorectal cancer (CRC) patients. With a growing survivor population, it is necessary to understand whether there are survival benefits across physical activity levels and across sociodemographic and clinical features. Methods: Disparities and Cancer Epidemiology (DANCE) is a population-based cohort of CRC survivors from metro-Detroit and Louisiana. Self-reported moderate and vigorous recreational physical activity was modeled continuously and categorically as none, low (<7.5 MET-hrs/wk), and high (7.5+ MET-hrs/wk). Survival models estimated hazard ratios (HRs) for physical activity with all-cause and CRC-specific survival. Models were stratified by sociodemographic and clinical features; cross-product terms estimated interaction with physical activity. Results: Of 1,107 participants, 26.5% were inactive, 49.1% had low physical activity, and 24.5% had high physical activity. Compared to inactivity, low activity was associated with 44% higher overall survival (HR= 0.56, 95% CI: 0.42, 0.75), and high activity with 66% higher survival (HR=0.34, 95% CI: 0.22, 0.53; P-trend=0.01). Adjustment for comorbidities, quality of life, BMI, and BMI-change did not alter results. Results remained significant for CRC-specific survival (low: HR=0.65, 95% CI: 0.44, 0.96; high: HR=0.45, 95% CI: 0.25, 0.80). Associations were consistent across sociodemographic and clinical features other than BMI and race; survival benefits were larger among White survivors. Conclusion: Any recreational physical activity is associated with longer overall and CRC-specific survival, regardless of sociodemographic or clinical characteristics for the most part. Any physical activity may have survival benefits for CRC survivors, but meeting physical activity guidelines may have the greatest benefit.

Abstract Background: Sarcopenia is associated with anabolic resistance, a blunted muscle protein synthesis response to protein ingestion. Here, we hypothesized that anabolic resistance may be associated with a delayed postprandial decline in circulating plasma amino acids following protein ingestion. We therefore wanted to investigate whether an oral protein tolerance test (OPTT) combined with untargeted plasma metabolomics can detect age-related or sarcopenia-related differences in amino acid time courses consistent with altered postprandial amino acid handling, which could potentially reflect reduced anabolic sensitivity. Moreover, we investigated whether metabolites other than amino acids reacted to the OPTT. Methods: Twelve young healthy adults (controls: 22-28 years) and 12 older adults with clinically diagnosed probable or confirmed sarcopenia (70-91 years) ingested 20 g of whey protein after an overnight fast. We collected venous blood at baseline, 1 h, and 2 h post-ingestion and analyzed the samples by untargeted LC-HRMS plasma metabolomics. Linear mixed-effects models were fitted for 2,968 metabolic features with Benjamini-Hochberg FDR correction. For each category (branched-chain amino acid, essential amino acid [EAA], total amino acid) we summed the within-subject log2 fold changes (FC); fold changes (FC) of the constituent amino acids. This composite is reported as the summed log2FC. Results: 201 metabolites were structurally annotated including 58 amino acid-related metabolites and 97 lipids. Fourteen of 17 proteinogenic amino acids increased significantly after protein ingestion (FDR<0.05). In young controls, essential amino acids rose more steeply at 1 h than in sarcopenic individuals (+10.06 +/- 1.05 vs. +7.84 +/- 1.58 summed log2FC) and declined more between 1 and 2 h (-4.93 +/- 1.29 vs. -0.20 +/- 2.27 summed log2FC). Leucine exemplified this pattern best, rising 1.74 log2FC in controls and declining to 0.96 at 2 h, while remaining elevated at 1.61 log2FC in the sarcopenic group at 2 h (p=0.009). Beyond amino acids, whey protein lowered circulating free fatty acids in both groups (FA 18:2, FA 18:1, FA 16:0; all FDR<0.05). Medium- and long-chain acylcarnitines (Car 8:0, Car14:2) declined postprandially in controls but remained elevated in sarcopenic individuals (p<0.05), suggesting altered postprandial lipid metabolism. Conclusion: In this proof-of-concept study, an OPTT showed that plasma EAAs declined more slowly from their postprandial peak in older adults with sarcopenia than in young adults, consistent with altered postprandial amino acid handling that may reflect anabolic resistance. Whey protein ingestion additionally modulates lipid and acylcarnitine metabolism in an age-dependent manner, suggesting broader alterations in postprandial metabolic regulation in older adults with sarcopenia.