Inflammaging is the age-related tendency of the immune system to slip into chronic inflammation in the absence of any external provocation such as injury or infection. Research into this phenomenon has produced a list of many different contributing mechanisms: the growing burden of senescent cells that produce pro-inflammatory signaling; excess visceral fat tissue that encourages the creation of senescent cells and provides pro-inflammatory signaling of its own; mitochondrial dysfunction that leads to mitochondrial DNA fragments escaping into the cell cytosol to maladaptively trigger mechanisms evolved to sense the presence of foreign DNA; and so forth. The resulting continual, unresolved inflammation is disruptive to tissue structure and function, an important contribution to age-related disease and mortality.
Over the past decade or so, researchers have shown that a number of hunter-gatherer populations exhibit much lower degrees of age-related dysfunction and disease than is the case in the populations of wealthy regions: a slower onset of neurodegeneration, and lower incidence of cardiovascular disease, for example. Hunter-gatherers undertake a great deal of physical activity relative to wealthier populations, and their diet is somewhat different. Today's research materials is a companion to a recent publication on the failure of chronic inflammation to greatly increase with age in Tsimane hunter-gatherers. Here, the same researchers compare the Tsimane and Moseten, near neighbor groups with differing degrees of adoption of modernity. Their data supports the consensus position that some of modernity, particularly the processed dietary options and lack of physical activity, are not so good for us.
Inflammaging is minimal among forager-horticulturalists in the Bolivian Amazon
An increase in chronic systemic inflammation in later life, termed inflammaging, is implicated in health risk. However, it is unclear whether inflammaging develops in all human populations, or if it is the product of environmental mismatch. We assessed inflammaging in Tsimane forager-horticulturalists of the Bolivian Amazon, using serum cytokines in a primarily cross-sectional sample (1,134 samples from n = 714 individuals, age 39-94, 51.3% female).
IL-6 was positively associated with age (β = 0.013). However, other pro-inflammatory markers, including IL-1β and TNF-α, did not increase with age (β = -0.005 and β = -0.001, respectively). We then compared the Moseten, a neighbouring population that has experienced greater market integration (423 samples from n = 380 individuals, age 39-85, 48.2% female). The Moseten also showed a positive age association for IL-6 that attenuated at later ages (age β = 0.025; age2 β = -0.001). Further, IL-1β and TNF-α were both positively associated with age (β = 0.021 and β = 0.011, respectively).
Our results demonstrate minimal inflammaging in the Tsimane, highlighting variation across populations in this age-related process. They also suggest that inflammaging is exacerbated by lifestyle shifts.
View the full article at FightAging
