Fasting and calorie restriction modulate age-associated immunosenescence and inflammaging

Aging is a multifaceted process impacting cells, tissues, organs, and organ systems of the body. Like other systems, aging affects both the adaptive and the innate components of the immune system, a phenomenon known as immunosenescence. The deregulation of the immune system puts elderly individuals at higher risk of infection, lower response to vaccines, and increased incidence of cancer. In the Western world, overnutrition has increased the incidence of obesity (linked with chronic inflammation) which increases the risk of metabolic syndrome, cardiovascular disease, and cancer. Aging is also associated with inflammaging a sterile chronic inflammation that predisposes individuals to age-associated disease. Genetic manipulation of the nutrient-sensing pathway, fasting, and calorie restriction (CR) has been shown to increase the lifespan of model organisms. As well in humans, fasting and CR have also been shown to improve different health parameters. Yet the direct effect of fasting and CR on the aging immune system needs to be further explored. Identifying the effect of fasting and CR on the immune system and how it modulates different parameters of immunosenescence could be important in designing pharmacological or nutritional interventions that slow or revert immunosenescence and strengthen the immune system of elderly individuals. Furthermore, clinical intervention can also be planned, by incorporating fasting or CR with medication, chemotherapy, and vaccination regimes. This review discusses age-associated changes in the immune system and how these changes are modified by fasting and CR which add information on interventions that promote healthy aging and longevity in the growing aging population. Aging is associated with the decline of immune function, increased incidence of infection, and cancer leading to an unhealthy and shorter lifespan. On the other hand, interventions like fasting and calorie restriction have been shown to promote healthier and longer lifespans by slowing/alerting the aging process.image