Circulating interleukin-37 declines with aging in healthy humans: relations to healthspan indicators and IL37 gene SNPs

Geroscience. 2023 Feb;45(1):65-84. doi: 10.1007/s11357-022-00587-3. Epub 2022 May 27.

Abstract

Aging is characterized by declines in physiological function that increase risk of age-associated diseases and limit healthspan, mediated in part by chronic low-grade inflammation. Interleukin (IL)-37 suppresses inflammation in pathophysiological states but has not been studied in the context of aging in otherwise healthy humans. Thus, we investigated associations between IL-37 and markers of healthspan in 271 young (18-39 years; n = 41), middle-aged (40-64 years; n = 162), and older (65 + years; n = 68) adults free of overt clinical disease. After conducting a thorough validation of AdipoGen's IL-37 ELISA, we found that plasma IL-37 is lower in older adults (young: 339 ± 240, middle-aged: 345 ± 234; older: 258 ± 175 pg/mL; P = 0.048), despite elevations in pro-inflammatory markers. As such, the ratios of circulating IL-37 to pro-inflammatory markers were considerably lower in older adults (e.g., IL-37 to C-reactive protein: young, 888 ± 918 vs. older, 337 ± 293; P = 0.02), indicating impaired IL-37 responsiveness to a pro-inflammatory state with aging and consistent with the notion of immunosenescence. These ratios were related to multiple indicators of healthspan, including positively to cardiorespiratory fitness (P < 0.01) and negatively to markers of adiposity, blood pressure, and blood glucose (all P < 0.05). Lastly, we correlated single-nucleotide polymorphisms (SNPs) in the IL37 and ILR8 (the co-receptor for IL-37) genes and found that variants in IL37 SNPs tended to be associated with blood pressure and adiposity (P = 0.08-0.09) but did not explain inter-individual variability in circulating IL-37 concentrations across age (P ≥ 0.23). Overall, our findings provide novel insights into a possible role of IL-37 in biological aging in humans.

Keywords: Anti-inflammatory; Cytokines; IL37; Immunosenescence; Single-nucleotide polymorphism.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • Aged
  • Aging* / genetics
  • C-Reactive Protein
  • Humans
  • Inflammation / genetics
  • Interleukin-1 / genetics
  • Interleukins / genetics
  • Middle Aged
  • Polymorphism, Single Nucleotide*

Substances

  • C-Reactive Protein
  • Interleukins
  • IL37 protein, human
  • Interleukin-1