Inflammaging markers characteristic of advanced age show similar levels with frailty and dependency

Abstract

The improvement of life quality and medical advances has resulted in increased life expectancy. Despite this, health status commonly worsens in the last years of life. Frailty is an intermediate and reversible state that often precedes dependency and therefore, its identification may be essential to prevent dependency. However, there is no consensus on the best tools to identify frailty. In this sense, diverse molecules have been proposed as potential biomarkers. Some investigations pointed to an increased chronic inflammation or inflammaging with frailty, while others did not report such differences. In this work, we evaluated the circulating concentration of the inflammaging markers in adults and older adults (aged over 70 years) by ELISA and Luminex techniques. The Barthel Index was applied for the evaluation of dependency and Timed up-and-go, Gait Speed, Short Physical Performance Battery, Tilburg Frailty Indicator and Gerontopole Frailty Screening Tool were used for the identification of frailty. CRP, TNF-α, IL-6 and albumin concentrations were measured, and we found that elevated inflammation is present in older adults, while no differences with frailty and dependency were reported. Our results were consistent for all the evaluated frailty scales, highlighting the need to reconsider increased inflammation as a biomarker of frailty.

Figure 1

Concentration of CRP in plasma. (A) There is elevated CRP (p < 0.0001****) in older adults (n = 111) compared to adults (n = 38). (B) Among older adults, CRP concentration has no correlation with age and (C) there is no significant difference between females and males. (D–H) No differences in CRP levels between robust and frail individuals were found for the 5 analysed frailty scales. (I) We also compared the individuals classified as robust or frail with all the tests (n = 40) or (J) with the 3 functional scales (TUG, GS and SPPB) (n = 63), but no differences were reported.

Figure 2

Concentration of TNF-α in plasma. (A) There is elevated TNF-α (p = 0.0006***) in older adults (n = 37) compared to adults (n = 39). (B) Among older adults, TNF-α concentration has no correlation with age and (C) there is no significant difference between females and males. (D–H) No differences in TNF-α levels between robust and frail individuals were found for the 5 analysed frailty scales. (I) We also compared the individuals classified as robust or frail with all the tests (n = 18) or (J) with the 3 functional scales (TUG, GS and SPPB) (n = 25), but no differences were reported.

Figure 3

Concentration of CRP in serum. (A) There is elevated CRP (p < 0.0001****) in older adults (n = 75) when compared to adults (n = 18). (B) Among older adults, CRP concentration has a positive correlation with age (p = 0.006**, r = 0.32 and 95% confidence interval 0.088–0.511) and (C) there is no significant difference between females and males. (D) Based on Barthel and TUG scales, no differences in CRP levels between robust, frail and non-autonomous individuals were found.

Figure 4

Concentration of TNF-α in serum. (A) There is elevated TNF-α concentration (p < 0.0001****) in older adults (n = 87) compared to adults (n = 18). (B) Among older adults, serum TNF-α concentration has a positive correlation with age (p = 0.0009***, r = 0.35 and 95% confidence interval 0.1425 to 0.5255) and (C) there is no significant difference between females and males. (D) Based on Barthel and TUG scales, there are no differences in TNF-α concentration between robust, frail and non-autonomous individuals.

Figure 5

Concentration of IL-6 in serum. (A) There is elevated IL-6 (p < 0.0001****) in older adults (n = 81) when compared to adults (n = 18). (B) Among older adults, serum IL-6 concentration has a positive correlation with age (p = 0.037*, r = 0.23 and 95% confidence interval 0.01–0.43) and (C) there is no significant difference between females and males. (D) Based on Barthel and TUG scales, no differences in IL-6 levels between robust, frail and non-autonomous individuals were reported.

Figure 6

Concentration of albumin in serum. (A) There are reduced levels of albumin (p = 0.0242*) in older adults (n = 87) when compared to adults (n = 18). (B) Among aged participants, albumin concentration has no correlation with age and (C) there is no significant difference between females and males. (D) Based on Barthel and TUG scales, no differences in albumin concentration between robust, frail and non-autonomous individuals were found.