A fundamental question in physiology is understanding how tissues adapt and alter their cellular composition in response to dietary cues. The mammalian small intestine is maintained by rapidly renewing LGR5^(+) intestinal stem cells (ISCs) that respond to macronutrient changes such as fasting regimens and obesogenic diets, yet how specific amino acids control ISC function during homeostasis and injury remains unclear. Here we demonstrate that dietary cysteine, a semi-essential amino acid, enhances ISC-mediated intestinal regeneration following injury. Cysteine contributes to coenzyme A (CoA) biosynthesis in intestinal epithelial cells, which promotes expansion of intraepithelial CD8αβ^(+) T cells and their production of interleukin-22 (IL-22). This enhanced IL-22 signalling directly augments ISC reparative capacity after injury. The mechanistic involvement of the pathway in driving the effects of cysteine is demonstrated by several findings: CoA supplementation recapitulates cysteine effects, epithelial-specific loss of the cystine transporter SLC7A11 blocks the response, and mice with CD8αβ^(+) T cells lacking IL-22 or a depletion of CD8αβ^(+) T cells fail to show enhanced regeneration despite cysteine treatment. These findings highlight how coupled cysteine metabolism between ISCs and CD8^(+) T cells augments intestinal stemness, providing a dietary approach that exploits ISC and immune cell crosstalk for ameliorating intestinal damage.

https://www.nature.com/articles/s41586-025-09589-5

Sarcopenia and the age-related decline in muscular strength and regenerative capacity contribute directly to loss of autonomy, greater risk for hospitalization and healthcare utilization. One contributing cellular phenotype associated with skeletal muscle aging is a loss in the function and number of resident muscle stem cells (MuSCs) or satellite cells. MuSC activation leads to dramatic changes in cellular architecture and metabolic reprogramming, including both mitochondrial biogenesis and increased glycolysis. Despite these changes to increase energy production, high energy demands may not be fully met during periods of MuSC activation. Here we used in vitro and in vivo approaches in mice to demonstrate the function of glutaminase for age-related changes in MuSC function. By combining fluorescence-activated cell sorting (FACS) isolation with metabolomics and stable isotope tracing, we show an age-related decline in reductive (counterclockwise) flux of glutamine through the tricarboxylic acid (TCA) cycle, a pathway by which MuSCs build cellular fatty acid stores as necessary biomass for MuSC function.

https://www.nature.com/articles/s43587-026-01120-3

Highlights

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Multimodal clocks define a quantitative framework for human aging

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Aging biomarkers and trajectories are highly conserved across multiple centers

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Plasma proteomic signals provide a compact, sensitive readout of systemic aging

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Coagulation-factor accumulation is identified as both a biomarker and driver of aging

Summary

Human aging is characterized by complex structural and functional decline, but quantifying its heterogeneity and assessing biological age remain challenges. We present the mCAS (multicentric Chinese aging standardized cohort) developed from 2,019 Chinese individuals aged 18–91 years. Integrating high-dimensional clinical, physiological, and molecular-level data, we constructed a three-tiered aging framework: the core capacity clock (CC-clock) to quantify clinical physiological decline, the multimodal clock (MM-clock) with extensive parameter coverage and enhanced predictive precision, and organ-associated aging clocks. Cross-layer analysis demonstrates that plasma protein clocks not only capture chronological age but also serve as efficient proxies for systemic physiological capacity. Leveraging this framework for discovery, we identified the age-dependent accumulation of coagulation factors as a driver of multi-organ senescence and systemic inflammatory activation. This study provides a foundational framework that bridges molecular signatures with functional decline, identifies new biomarkers for aging assessment, and reveals a novel translational driver of aging.

https://www.cell.com/cell/abstract/S0092-8674(26)00460-5