Study Shows Inflammation Not Always Linked to Ageing in Industrialized Indigenous Groups

Inflammation may not always be related to ageing and appears to be a consequence of industrialised lifestyles, researchers said, after they found high levels of inflammation in two indigenous populations, which neither increased with age nor led to chronic conditions.

The findings, published in the journal Nature Aging, challenge current notions around persistent inflammation related to ageing -- or 'inflammaging', the authors said.

'These results point to an evolutionary mismatch between our immune systems and the environments we now live in. Inflammaging may not be a direct product of ageing, but rather a response to industrialised conditions,' lead author Alan Cohen, associate professor of environmental health sciences at Columbia University, US, said.

They added that a holistic approach, looking at culture, environment and lifestyle factors, needs to be taken while studying ageing processes.

'In industrialised settings, we see clear links between inflammaging and diseases like chronic kidney disease,' Cohen said.

'But in populations with high infection rates, inflammation appears more reflective of infectious disease burden than of ageing itself,' the lead author said.

The researchers looked at four populations -- two industrialised ones from Italy and Singapore and two indigenous, non-industrialised communities, called the 'Tsimane' of the Bolivian Amazon and the 'Orang Asli' of peninsular Malaysia.

Inflammation levels due to ageing were found to be similar between the two industrialised populations studied, but did not hold in the indigenous groups, where inflammation was found to be driven largely by infection rather than age.

Further, the inflammation seen in the native communities did not increase with age and also did not result in chronic diseases -- such as diabetes, heart disease and Alzheimer's -- a regular feature of modern, industrialised societies, the researchers said.

'Infammaging, as measured in this manner in these cohorts, thus appears to be largely a byproduct of industrialised lifestyles, with major variation across environments and populations,' the authors wrote.

They added that chronic diseases are rare or even absent among native populations, meaning that even when the young in these communities have profiles that look similar on the surface to those of older industrialised adults, they do not lead to disease.

'These findings really call into question the idea that inflammation is bad per se. Rather, it appears that inflammation – and perhaps other aging mechanisms too – may be highly context dependent,' Cohen said.

'On one hand, that's challenging, because there won't be universal answers to scientific questions. On the other, it's promising, because it means we can intervene and change things,' the author said.

The study analysed a group of 19 cytokines -- proteins created during immune and inflammatory responses -- and found patterns in line with ageing among the Italian and Singaporean individuals, but not among the 'Tsimane' and 'Orang Asli'.

The immune systems of the indigenous populations were shaped by persistent infections and distinct environmental exposures, the researchers said.