Inflammatory biomarkers of frailty

Frailty is a functional term that describes a decline in physiological functions that leads to dependency, vulnerability to stressors, high risk for adverse health outcomes, increased risk of falls, and increased morbidity and mortality. The central role of inflammation and the cross-talk between frailty and sarcopenia have led to a condition termed physical frailty, in which muscle atrophy is viewed as the biological substratum of physical frailty. Different paradigms of ageing, including "inflamm-ageing", "oxi-inflamm-ageing", and "inflamm-inactivity" reveal inflammation as a common driver of age-related frailty. The key role of inflammation in frailty conditions have led to numerous studies screening for potential inflammatory biomarkers of frailty. This review summarizes the present knowledge of inflammatory biomarkers that are considered promising tools to evaluate frailty. Inflammatory biomarkers for different pathophysiological pathways have been identified, and can be divided into markers of inflammation, oxidative stress, muscle protein turnover and physical inactivity. Described candidate inflammatory biomarkers could support diagnosis, prognosis, and therapeutic decisions in frail elderly. Furthermore, exercise training and nutritional counselling could be implemented in the standard care of the elderly in order to prevent, delay, or ameliorate frailty and to reduce the levels of blood inflammatory biomarkers. Such tools and decision-making outcomes would improve selection and treatment of the elderly and contribute to the ultimate goal - healthy ageing.