Fight Aging!

Cartilage tissue exhibits a relatively poor capacity for regeneration even in youth, but this capacity for maintenance and repair diminishes with age. There are thus some gains to be made in understanding why this happens and developing means of rejuvenation, but ultimately some form of regenerative medicine above and beyond natural degrees of healing will be needed in order to completely address the very prevalent joint issues that occur in later life and culminate in disabling degrees of cartilage loss and osteoarthritis. While this is widely studied, cartilage has so far proven to be a difficult tissue for the tissue engineering community to reproduce and manipulate. The load-bearing capacity and resilience necessary for its function in the body requires an accurate recreation of the complex extracellular matrix structure and cell behavior; pseudo-tissues of the sort that work well in tissue engineering for many organs are not good enough for cartilage.

Returning to the question of why cartilage tissue becomes less regenerative with age, in today's open access paper the authors turn their attention to macrophages. Macrophages of the innate immune system are present in large numbers in tissues throughout the body, and are deeply involved in the intricate processes that accompany tissue regeneration and tissue maintenance. Researchers have discovered a regulatory gene for macrophage behavior in cartilage that biases these cells towards pro-regenerative, anti-inflammatory patterns of behavior. Expression declines with age, however, and thus macrophages become increasingly inflammatory, leading to a reduced capacity for cartilage tissue maintenance and regeneration. Given the expression of this gene as a target, therapies can now be designed and tested to improve cartilage maintenance in older individuals.

Single-cell omics reveals arg-1 as a key regulator of age-dependent macrophage-mediated cartilage repair

Aging is a significant factor influencing the recovery capacity following cartilage injury, with notable differences observed between older and younger animals. Studies indicate that younger animals exhibit enhanced regenerative potential, including better cartilage repair and reduced inflammatory responses, compared to their older counterparts. This disparity may be attributed to age-related declines in stem cell activity, extracellular matrix synthesis, and immune function.

Macrophages play a multifaceted and context-dependent role in the pathogenesis of cartilage injury, contributing to both inflammatory progression and tissue repair. In the synovial microenvironment, macrophages exhibit remarkable plasticity, dynamically shifting between pro-inflammatory (M1-like) and anti-inflammatory (M2-like) phenotypes in response to local signals. While M1-polarized macrophages drive joint inflammation through the production of cytokines such as tumor necrosis factor-α (TNF-α), Interleukin-1β (IL-1β), and Interleukin-6 (IL-6), M2-like macrophages promote resolution of inflammation and tissue remodeling. However, this dichotomy is oversimplified, as single-cell studies reveal a spectrum of macrophage activation states in cartilage injury, with distinct subsets associated with disease severity and treatment response. Furthermore, synovial macrophages interact with fibroblasts, T cells, and osteoclasts, forming a complex cellular network that perpetuates joint destruction.

Our study employed single-cell RNA sequencing (scRNA-seq) to investigate the differential recovery capacity between young and aged animals following cartilage injury, explicitly addressing the inherent heterogeneity of immune cells within the joint. Through comprehensive profiling of joint tissues before and after injury, we aimed to identify age-dependent molecular mechanisms that govern post-injury recovery. Our analysis revealed that young animals exhibit a significantly higher proportion of anti-inflammatory macrophage subsets compared to aged counterparts, suggesting a link between specific immune cell states and enhanced tissue repair potential.

Further network analysis pinpointed Arg-1 (Arginase-1) as a central regulator within anti-inflammatory macrophages. Functional validation through in vivo and in vitro experiments demonstrated that Arg-1 overexpression inhibited inflammation and reactive oxygen species release in aged animals, partially rescuing their impaired recovery phenotype. These results not only elucidate the mechanistic basis for age-related disparities in cartilage injury recovery but also highlight Arg-1 as a novel therapeutic target to improve joint repair in elderly individuals. By integrating single-cell omics with mechanistic validation, this study provides critical insights into anti-inflammation macrophage in cartilage injury and offers a potential strategy to mitigate age-associated decline in tissue regeneration.

As the understanding of more recently discovered modes of programmed cell death are fleshed out, they receive greater attention from various groups focused on specific aspects of aging. In this review the programmed cell death mechanism is PANoptosis and the area of focus is the aging of the heart. Some means of preventing overly aggressive, maladaptive programmed cell death in the context of aging have performed fairly well in animal studies, but the details matter and progress towards useful therapies is ever slow and uncertain.

As the vital power organ of the human body, the health of the heart directly determines an individual's quality of life and longevity. With the accelerating global aging population, cardiac aging-related diseases have become a major public health threat. Although existing interventions (e.g., senolytics) can delay cardiac aging to some extent, their efficacy remains limited, necessitating the exploration of novel mechanisms to develop more effective therapeutic strategies.

In recent years, PANoptosis - an integrated cell death pathway - has emerged as a new research focus in cardiac aging. PANoptosis, a recently defined lytic cell death modality, integrates core molecular mechanisms of pyroptosis, apoptosis, and necroptosis into a dynamically regulated "death signaling network". As a unique programmed cell death paradigm, it transcends classical boundaries of these pathways by forming the PANoptosome complex, which orchestrates caspase family members. It may contribute to cardiac functional decline by accelerating cardiomyocyte loss, fibrosis, and chronic inflammation.

Targeting PANoptosis-based intervention strategies (e.g., gene editing, RNAi, combination therapy, and novel delivery systems) has demonstrated significant therapeutic potential, offering new preclinical avenues to delay or alleviate cardiac aging. This review summarizes the molecular mechanisms and roles of PANoptosis in cardiac aging, including its regulatory networks, key evidence driving cardiac aging, and targeted intervention strategies, thereby providing a theoretical foundation for developing PANoptosis-targeted therapies against cardiac aging.

Link: https://doi.org/10.3389/fcvm.2026.1759908

Does the correlation between late life vaccination and reduced risk of neurodegenerative conditions such as Alzheimer's disease exist because vaccination produces benefits such as reduced chronic inflammation via trained immunity, or because people who undergo vaccination tend to be more diligence in all matters relating to health? Mechanistic or behavioral, or both? And if both, how much of the overall observed effect size arises from each side? Researchers here find a way to obtain more insight into this correlation, as they show that different vaccine doses correlate with different degrees of reduced dementia risk. We should not expect this to be the case unless the outcome is driven by biological mechanisms resulting from vaccination.

Previous studies, including large cohort analyses comparing vaccinated and unvaccinated adults, suggest that routine immunizations such as inactivated influenza vaccines (IIVs) may reduce Alzheimer dementia (AD) risk. Whether AD risk differs after high-dose IIV (H-IIV) vs standard-dose IIV (S-IIV) remains unexamined. We hypothesized that AD risk would be lower among adults ≥65 years after H-IIV compared with S-IIV.

This retrospective cohort study analyzed data spanning 2014-2019 from IQVIA PharMetrics Plus for Academics, a US health care claims database. Eligible participants were ≥65 years with ≥2 years of continuous medical and pharmaceutical coverage and no previous diagnostic or pharmacotherapeutic indicators of cognitive impairment. Vaccinations were identified by name and Current Procedural Terminology codes. Participants were followed for up to 3 years postvaccination. Incident AD was defined using International Classification of Diseases codes and AD medication dispenses (cholinesterase inhibitors, memantine).

The H-IIV group included 120,775 unique participants (185,183 person-trials; mean age 74.4 ± 5.5 years; 57.3% female), and the S-IIV group included 44,022 participants (53,918 person-trials; mean age 73.0 ± 6.1; 56.4% female). H-IIV was associated with significantly lower AD risk during months 1-25 postvaccination. Further research is needed to clarify whether the observed difference reflects protection against influenza infection or non-infection-related mechanisms.

Link: https://doi.org/10.1212/WNL.0000000000214782