Prospective effects of perceived stress on immunosenescent principal components in older adults

Abstract

Stress may drive aspects of immunological aging. The present investigation examined how perceived stress across five years predicts immunosenescence one year later, using principal component analysis as a dimension-reduction technique to characterize natural killer (NK) and T cell surface markers that independently contribute to variability in immunosenescence in older adults ( N = 140, 43% male, aged 60–92). Three principal components (PC) were identified. PC1 (49% variance explained) included indicators of NK cell exhaustion (NK56 dim : NKG2C+, FCR γ -, NKG2C + CD57+, NKG2C + FCR γ -, and FCR γ -CD57+). PC2 (23% variance explained) included indicators of T cell senescence (CD8+: CD28-, CD57+, and CD56+). PC3 (10% variance explained) included NK56dimCD57+. In a subset of older adults ( n = 68), perceived stress was measured biannually for up to five years preceding immune assessment. Person-specific perceived stress slopes and intercepts (centered at the last time point) were outputted and tested as main and interacting effects on PCs in regressions. There was a significant stress slope*intercept interaction predicting PC2 ( b = −53.5, SE = 18.85, p = 0.006). Older adults who decreased over time and ended low in perceived stress had the lowest PC2 levels ( b = 1.33, p = 0.004), whereas older adults who increased over time in stress had similar (high) PC2 levels whether or not they ended low/high in stress ( b = −0.81, p = 0.14). Ultimately, decreasing stress to low levels may retard age-associated aspects of T cell senescence and to a greater degree than NK cell aging in older adults.