Aging and low-grade inflammation reduce renal function in middle-aged and older adults in Japan and the USA

Abstract

The objective of this study was to investigate the effects of low-grade inflammation on age-related changes in glomerular filtration rate (GFR) in middleaged and older white Americans, African-Americans, and Japanese adults. Serum creatinine, C-reactive protein (CRP), and interleukin-6 (IL-6) levels were determined for 1570 adult participants in two surveys of aging in the USA and Japan (N = 1188 and 382, respectively). Kidney function declined with age in both countries and was associated with IL-6 and CRP. IL-6 and CRP also influenced the extent of the arithmetic bias when calculating the GFR using the chronic kidney disease epidemiology (CKD-EPI) formula with just serum creatinine. Younger African-Americans initially had the highest GFR but showed a steep age-related decrement that was associated with elevated inflammation. Japanese adults had the lowest average GFR but evinced a large effect of increased inflammatory activity when over 70 years of age. Importantly, our results also indicate that low-grade inflammation is important to consider when evaluating kidney function solely from serum creatinine.

Renal Aging: Causes and Consequences

“…Inflammation is increased within the aging kidney in humans, with proinflammatory cytokines detectable in the serum correlating with age-related renal disease. 155,156…”

C‐reactive protein and ageing

“…In the current literature, the common ageing‐related diseases and conditions associated with increased CRP levels include CVD, hypertension, diabetes mellitus, chronic kidney injury, Alzheimer's disease and Parkinson's disease …”

“…Ethnic determinants may account for differences in CRP levels and their change over time, as studies have shown that younger African Americans have a steeper age‐related decline in eGFR, which is associated with increasing CRP, compared with non‐African Americans. Whereas Japanese elderly, for example, began to have steep changes in eGFR and indications of increased inflammatory activity after age 70 years …”

“…C‐reactive protein, an acute phase protein, is primarily produced and secreted by the liver and is an important risk factor associated with ageing‐related diseases including cardiovascular disease (CVD), hypertension, diabetes mellitus, kidney disease and cognitive decline . However, recent studies have also shown that CRP is an important immunologic effector molecule with vital physiological functions .…”

Age and Gender-Related Changes in Renal Haemodynamics of Albino Rats: The Possible Role of Cytokines and Prostaglandins

“…Inflammation is increased within the aging kidney in humans, with pro inflammatory cytokines detectable in the serum correlating with age-related renal disease [35,36] . The increase of IL-6 may contribute, along with other proinflammatory factors, to the onset of many of the chronic age related diseases [37] , and may also be associated with mortality [38] .…”