Immunosenescence is a therapeutic target for frailty in older adults: a narrative review

BACKGROUND AND OBJECTIVE: Aging refers to a progressive decrease in functional performance, leading to increased mortality risk. At present, life expectancy is increasing worldwide and is expected to exceed 80 years by 2040. However, this increase in life expectancy also indicates a rise in the incidence and prevalence of diseases, such as cardiovascular, neurological, musculoskeletal, and oncological diseases, which are associated with aging. The exact underlying mechanisms of aging remain unknown, and whether it is a programmed process or the consequence of an accumulation of stress events remains unclear. Thus, more scientific research is needed to improve the management of complex and frail patients. METHODS: Several databases were searched with the following key words: immunosenescence, inflamm-aging, frailty, sarcopenia and skeletal muscle, etc. KEY CONTENT AND FINDINGS: Skeletal muscle is the core phenotype of frailty and sarcopenia. Immune aging and skeletal muscle decline interplay with each other and form a vicious circle. Maintaining muscle health is beneficial for immune function and delays the onset of frailty. Particularly, in the context of the ongoing corona virus disease (COVID)-19 pandemic, studies have shown that the elderly are more prone to the consequences of the SARS-CoV-2 virus. It has been reported that the rates of hospitalization in the 65–74, 75–84, and ≥85 years old group were 5×, 8×, and 10× greater than the 18–29 years old group, with corresponding COVID-19-related deaths being 60×, 140×, and 330× that of the younger reference group, respectively. Considering the above, this review aims to discuss the relationship between immunosenescence, skeletal muscle, and frailty, and to explore immunosenescence as a potential therapeutic target to prevent frailty and extend healthspan, with some emphasis on the effects of the COVID-19 pandemic on the elderly. CONCLUSIONS: Immunosenescence is a promising potential therapeutic target for frailty and is worthy of further investigation.