Kuchel, George A.

Cellular senescence is an irreversible stress response, which leads to loss of cellular function and remodeling of the cellular secretory profile. In humans, pancreatic β cells undergo cellular senescence during the progression to type 2 diabetes (T2D). However, the mechanism linking β cell senescence to islet dysfunction remains unknown, and thus the therapeutic potential of targeting senescent cells in T2D is not established. Herein, we identified a subpopulation of senescent β cells expressing p21, which emerged early in the progression of T2D in humans and mice. Spatial transcriptomics and proteomics analyses confirmed senescence and loss of cellular identity in this subpopulation in humans. Functional analysis revealed lack of glucose responsiveness, high basal insulin secretion, and transcription of senescence-associated secretory phenotype (SASP) factors. SASP factors from p21 + β cells induced secondary senescence in neighboring cells, characterized by dysfunction and loss of identity. JAK inhibitors counteracted the induction of secondary senescence and restored β cell function in islets from humans with T2D and in mice fed a high-fat diet. These findings reveal the critical role of p21 + β cells in T2D pathogenesis and the therapeutic potential of targeting this pathophysiological process.

ABSTRACT Biological aging greatly impacts the body’s ability to handle glucose, and represents a major risk factor the development and progression of type 2 diabetes (T2D). Nonetheless, despite advances in cellular senescence research and the development of new senolytic therapies, the heterogeneity of cellular senescence in the human endocrine pancreas, as well as its roles in normal aging, remains to be elucidated at the single-cell level. Here, we performed single-cell–resolved spatial proteomics and transcriptomics on intact pancreas from 26 donors (ages 20–80) and multiplexed single-cell RNA sequencing and functional assays on dispersed islets from 14 donors (ages 34–69). We identify two discrete SnC subpopulations distinguished by relative expression of CDKN1A and CDKN2A. CDKN1A ⁺ senescent cells (SnCs) exhibit loss of β-cell identity, impaired insulin secretion, and a proinflammatory SASP associated with increased islet immune infiltration. In contrast, CDKN2A ⁺ SnCs retain transcriptional identity and functional competence, with lower inflammatory signaling. Together, these findings identify heterogeneous and functionally divergent senotypes in the human pancreas, distinguishing an adaptive ( CDKN2A ⁺) from a maladaptive ( CDKN1A ⁺) senescence program, thus providing a mechanism-guided framework for senescence-targeted therapies in T2D.

Abstract Approximately 17% of people aged 65 years and older are anemic, and 10% of death certificates report anemia as a secondary cause of death in the United States. Nonetheless, anemia remains unexplained in 30%-50% of older adults. This unexplained anemia of aging (UAA) is a diagnosis of exclusion. The mechanism, impact, and progression of UAA remain unknown. At older ages, anemia adds to pre-existing co-morbidities with significant adverse health consequences, representing a compelling unmet clinical concern. The National Institute on Aging held a workshop in 2024 to discuss current knowledge and research opportunities. Topics included the epidemiology of anemia at older age and its clinical implications; probable mechanism(s) underlying UAA, that is, low-grade inflammation’s effects on erythropoiesis; the role of microbiota in iron regulation in bone marrow; the importance of ruling out a diagnosis of leukemic clonal hematopoiesis (CH), which is more prevalent in older age; the role of senescence and aging governing hematopoiesis; and the effects of sex hormones on hematopoietic stem cell aging. Understanding the roles of these factors could reduce the proportion of the older anemic population whose anemia remains unexplained and offer insights into new potential diagnostic and intervention strategies. Speakers reviewed previous clinical trials in patients with UAA and CH. They discussed lessons learned and future research priorities, including efforts to develop new diagnostic algorithms and potential uses of machine learning.

ABSTRACT Cellular senescence is a stress response mechanism marked by irreversible growth arrest, upregulation of antiapoptotic pathways, loss of cellular function, and remodelling of the cellular secretory profile. In both humans and mice, pancreatic β-cells undergo senescence with age and insulin resistance. Targeted removal of senescent cells in mouse models of diabetes improves glucose homeostasis, demonstrating the role β-cell senescence in diabetes progression. In contrast, β-cell senescence also promotes immune surveillance, promoting β-cell survival and function. Thus, a better understanding of senescent cells’ phenotypic and functional heterogeneity is needed to develop effective therapeutic strategies. Herein, we show that subpopulations of senescent β-cells in mice and humans, which were identified through the expression of Cdkn1a (encoding p21 Cip1 ) and Cdkn2a (encoding p16 Ink4a ) by single-cell RNA sequencing (scRNA-seq), flow cytometry, spatial transcriptomics, and spatial proteomics, exhibit distinct transcriptional and functional identities. The predominant senescent β-cell subpopulation expressed Cdkn1a and was characterized by a lack of glucose responsiveness, high basal insulin secretion, and transcription of canonical SASP factors. The SASP of Cdkn1a -expressing β-cells had non-cell autonomous effects on neighbouring cells. A subset of four SASP factors from Cdkn1a + cells was sufficient to induce secondary senescence and β-cell dysfunction in vitro . JAK inhibitors (JAK1/2 and JAK1/3) counteracted secondary senescence induction and restored β-cell function in high-fat diet-fed mice and human islets from donors with or without type 2 diabetes. GRAPHICAL ABSTRACT

Abstract The National Institute on Aging-funded Geroscience Education and Training Network held the “Building an Interdisciplinary Workforce in Geroscience: Aligning Perspectives and Educational Goals” preconference workshop at the 2023 Gerontological Society of America’s Annual Meeting. Parties involved in geroscience education and interested stakeholders addressed the development of didactic educational materials, training, and career development opportunities to equip learners with the skills to meet the demands of the emerging field of geroscience, from research to clinic and industry. Recent successes were presented, existing opportunities, gaps, and challenges identified and discussed, and solutions and future directions described.

Abstract The inaugural Canadian Conferences on Translational Geroscience were held as 2 complementary sessions in October and November 2023. The conferences explored the profound interplay between the biology of aging, social determinants of health, the potential societal impact of geroscience, and the maintenance of health in aging individuals. Although topics such as cellular senescence, molecular and genetic determinants of aging, and prevention of chronic disease were addressed, the conferences went on to emphasize practical applications for enhancing older people’s quality of life. This article summarizes the proceeding and underscores the synergy between clinical and fundamental studies. Future directions highlight national and global collaborations and the crucial integration of early-career investigators. This work charts a course for a national framework for continued innovation and advancement in translational geroscience in Canada.

People with HIV on combination antiretroviral therapy (ART) have longer life expectancy and are increasingly experiencing age-related comorbidities. Thus, aging with HIV has become a central issue in clinical care and research, which has been particularly challenging with the intersection of the ongoing coronavirus (COVID)-19 pandemic. Since 2009, the International Workshop on HIV and Aging has served as a multidisciplinary platform to share research findings from cross-disciplinary fields along with community advocates to address critical issues in HIV and aging. In this article, we summarize the key oral presentations from the 12th Annual International Workshop on HIV and Aging, held virtually on September 23rd and 24 th , 2021. The topics ranged from basic science research on biological mechanisms of aging to quality of life and delivery of care under the COVID-19 pandemic. This workshop enriched our understanding of HIV and aging under the COVID-19 pandemic, identified challenges and opportunities to combat the impact of COVID-19 on HIV communities, and also provided updated research and future directions of the field to move HIV and aging research forward, with the ultimate goal of successful aging for older people with HIV.

This editorial comments on the article by Siddique et al .