Longevity Briefs: Is Modernisation Messing With Your Immune System?

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

The problem:

Inflammageing is a term used to describe a rise in chronic inflammation with age. Inflammation is the immune system’s first line of defence against pathogens, helping to keep them at bay until the more targeted immune response involving T and B cells can come to the rescue. However, as we grow older, inflammation increasingly occurs throughout the body in the absence of any threat, and this slowly damages our tissues over time, driving many age-related diseases.

How does this happen? There are multiple contributing factors. For example, the ageing stem cells in the bone marrow tend to produce more inflammatory white blood cells with age. An increasing number of senescent cells also drive up inflammation by releasing a cocktail of inflammatory molecules. However, environmental factors are also likely to be important contributors. Consumption of ultra-processed food is associated with increased inflammation, as is a sedentary lifestyle. Modern hunter-gatherer tribes offer unique opportunities to study the effects of such lifestyle factors, as they are usually physically active by necessity and eat unprocessed foods almost exclusively throughout their lives. In this study, researchers ask to what extent inflammageing still progresses in such groups.

The discovery:

In the study, researchers took blood samples from 714 Tsimane adults. The Tsimane are an indigenous population of the Bolivian Amazon – you might even remember them from a previous study we covered. They used these blood samples to compare levels of different inflammatory molecules at different ages. They found that older age was associated with a significant increase in interleukin 6 (IL-6), an important inflammatory molecule that performs a range of functions. However, other notable inflammatory molecules like TNF-α (well documented to increase with age) and interleukin-1β (IL-1β) did not show statistically significant increases with age in the Tsimane population.

The researchers then compared these results to those of 423 blood samples from a neighbouring indigenous population: the Moseten. The Moseten have close historical ties to the Tsimane, but are more integrated with modern markets (they rely less on hunting and gathering) and live in closer proximity to industrialised societies. The researchers found that in this population, TNF-α and IL-1β both increased significantly with age in addition to IL-6.

The implications:

Modernisation has generally been an excellent thing for human health and life expectany – just look at how long people used to live a few hundred years ago. However, our relationship with modernisation is probably accelerating the rate at which we age in various ways.

This research suggests that inflammageing could be driven by environmental factors to a substantial degree, and that lifestyle factors like diet and exercise could have a very significant impact on inflammageing and thereby prevent age-related diseases. Though the Tsimane have lower life-expectancy than most industrialised societies (largely due to lack of healthcare access), they do appear to have fewer age-related diseases like dementia and cardiovascular diseases at a given age.

As with any observational study, it is impossible to prove causation here. We cannot know whether physical activity, diet, exposure to environmental pollution (due to proximity to major settlements), stress related to discrimination or some other unknown factor is responsible for the differences in inflammageing between the Tsimane and Moseten.