Improved assessment of overall health in variably aged murine models of Multiple Sclerosis with a novel frailty index tool

Experimental autoimmune encephalomyelitis pathogenesis alters along animal age: impact of S100B expression

Multiple Sclerosis (MS) is the leading inflammatory and non-traumatic cause of disability in young adults, with late-onset MS emerging in middle-aged patients often resulting in poorer treatment responses and worse prognoses. The calcium-binding protein S100B is elevated in MS patients, and its targeting has shown promise in reducing disease severity in experimental autoimmune encephalomyelitis (EAE) models. However, most studies on MS pathology have focused on young animal models, leaving a gap in understanding the effects of age and S100B ablation on disease progression throughout the lifespan. This study aimed to characterize EAE in mice of different ages, examining demyelination, inflammation, and immune responses to determine whether S100B ablation could mitigate MS pathogenesis across the lifespan. EAE was induced in six cohorts of C57BL/6 mice: young adults (3 months), older adults (6 months), and middle-aged (12 months), including corresponding S100B knockout (KO) groups, followed for 23 days. Upon sacrifice, spinal cords were assessed via immunohistochemistry and Real-Time qPCR, while splenocytes were analyzed for immune cell characterization. Results indicated a more severe disease course in 12-month-old mice, marked by increased gliosis, inflammation, and impaired microglial phagocytic activity. Notably, S100B absence reduced gliosis and inflammatory markers across all ages, with 12-month-old S100B KO mice showing increased regulatory T cells. These findings highlight the exacerbating role of age and elevated S100B in MS progression, underscoring the importance of identifying age-specific MS markers and therapeutic targets.

Exploring In Vivo Models of Musculoskeletal Frailty: A Comprehensive Systematic Review

Musculoskeletal frailty-a common and debilitating condition linked to aging and chronic diseases-presents a major public health issue. In vivo models have become a key tool for researchers as they investigate the condition's underlying mechanisms and develop effective interventions. This systematic review examines the current body of research on in vivo models of musculoskeletal frailty, without any time constraints. To achieve this aim, we utilized three electronic databases and incorporated a total of 11 studies. Our investigation delves into varied animal models that simulate specific features of musculoskeletal frailty, including muscle loss, bone density reduction, and functional decline. Furthermore, we examine the translational prospects of these models in augmenting our comprehension of musculoskeletal frailty and streamlining the production of groundbreaking therapeutic approaches. This review provides significant insights and guidance for healthcare researchers and practitioners who aim to combat musculoskeletal frailty, ultimately enhancing the quality of life for older adults and individuals affected by this condition.

Frailty in rodents: Models, underlying mechanisms, and management

Frailty is a clinical geriatric syndrome characterized by decreased multisystem function and increased vulnerability to adverse outcomes. Although numerous studies have been conducted on frailty, the underlying mechanisms and management strategies remain unclear. As rodents share homology with humans, they are used extensively as animal models to study human diseases. Rodent frailty models can be classified broadly into the genetic modification and non-genetic modification models, the latter of which include frailty assessment models (based on the Fried frailty phenotype and frailty index methods) and induced frailty models. Such models were developed for use in investigating frailty-related physiological changes at the gene, cellular, molecular, and system levels, including the organ system level. Furthermore, exercise, diet, and medication interventions, in addition to their combinations, could improve frailty status in rodents. Rodent frailty models provide novel and effective tools for frailty research. In the present paper, we review research progress in rodent frailty models, mechanisms, and management, which could facilitate and guide further clinical research on frailty in older adults.