The Impact of IL-6 on Future Aging Phenotypes

The Impact of IL-6 on Future Aging Phenotypes

Interelukin-6 is a proinflammatory cytokine. It is also known that IL-6 stimulates other downstream inflammatory markers like C-reactive protein and fibrinogen. A recent study has determined that chronically elevated levels of IL-6 are associated with unhealthy aging phenotypes and a decreased likelihood of successful aging.

This study was conducted over 10 years. I now appreciate this length of time more after reading previous research articles and comparing the span of this study to others. Additionally, the researchers included 3,044 participants in their study. I believe this is a substantial number of human participants and that this contributes to the credibility of their findings. The 3,044 included had no history of stroke, cancer, or myocardial infarction.

IL-6 was measured in the participants by using high sensitivity enzyme linked immunosorbent assay every five years for a period of 10 years. Health behaviors such as smoking status and activity level were also taken into consideration. Sociodemographic data on the participants’ age, sex, socioeconomic status was collected. At the 10 year follow up the patients were classified as one of four aging phenotypes: successful aging, normal aging, fatal or nonfatal cardiovascular disease (CVD) event, or non-CVD death.

There were 721 participants that were classified as successful aging, 321 had CVD events, 147 died from non-CVD events, and 1,855 were classified as normal aging. The IL-6 levels were compared between the four phenotypes. It was found that participants with high IL-6 at the baseline were significantly less likely to achieve successful aging, an increased risk of a CVD event, or death from a non-CVD cause over the 10 year follow up period. Additionally, participants with high IL-6 once or twice over the 5-year evaluation periods were less likely to achieve successful aging, increased risk of a CVD event, and increased risk of death from a non-CVD cause. High IL-6 levels measured twice over the 5-year exposure period were associated with half the odds of successful aging. The associations found were independent of socioeconomic factors, health behaviors, health conditions, and the use of inflammatory drugs. More simply, the results suggest that maintaining low IL-6 levels reduce the likelihood of impaired musculoskeletal and respiratory functioning and increase the likelihood of remaining diabetes free.

I thought the study was interesting and verified the relationship between IL-6 and chronic inflammation that we have discussed with previous articles. However, one important limitation of this study that the researchers noted is that elevated IL-6 levels at the beginning and end of a 5-year exposure period should not necessarily be regarded as an indicator of chronic inflammation, because repeated short-term inflammatory responses are also possible.

Sources:

Akbaraly, Tasnime N., Mark Hamer, Jane E. Ferrie, Gordon Lowe, G. Batty, Gareth Hagger-Johnson, Archana Sing-Manoux, Martin J. Shipley, and Mika Kivimaki. "Chronic Inflammation as a Determinant of Future Aging Phenotypes." Canadian Medical Association Journal (2013): n. pag. 16 Sept. 2013. Web. 11 Oct. 2013.