Age-related Differences in T-cell Subsets and Markers of Subclinical Inflammation in Aging Are Independently Associated With Type 2 Diabetes in the Health and Retirement Study

OBJECTIVES

Age-related changes in adaptive immunity and subclinical inflammation are both important risk factors for diabetes in older adults. We evaluated the independent association between T-cell subsets, subclinical inflammation, and diabetes risk in the Health and Retirement Study (HRS).

METHODS

We measured 11 T-cell subsets, 5 pro-inflammatory markers, and 2 anti-inflammatory markers from the 2016 wave of the HRS (baseline). Diabetes/prediabetes status was estimated at the 2016, 2018, and 2020 waves of HRS, based on levels of blood glucose/glycated hemoglobin in plasma or self-reported status. We used survey generalized logit models to evaluate the cross-sectional associations and Cox proportional hazard models to evaluate longitudinal associations.

RESULTS

Among 8,540 participants (56 to 107 years of age), 27.6% had prevalent type 2 diabetes and 31.1% had prediabetes in the 2016 survey. After adjusting for age, sex, race/ethnicity, education, obesity, smoking, comorbidity index, and cytomegalovirus seropositivity, individuals with type 2 diabetes had lower naive T cells and higher memory and terminal effector T cells as compared with normoglycemic individuals. Among 3,230 normoglycemic participants in the 2016 survey, the incidence of diabetes was 1.8% over 4 years of follow-up. The baseline percentage of CD4+ effector memory T cells was associated with a lower risk of incident diabetes (hazard ratio [HR]=0.63, 95% confidence interval [CI] 0.49 to 0.80, p=0.0003) after adjustment for covariates. Baseline level of interleukin-6 (IL-6) was associated with risk of incident diabetes (HR=1.52, 95% CI 1.18 to 1.97, p=0.002). The associations between age-related changes in CD4+ effector memory T cells and risk of incident diabetes remained unchanged after adjustment for subclinical inflammation, although adjusting for CD4+ effector memory T cells nullified the association between IL-6 and incident diabetes.

CONCLUSIONS

This study showed that the baseline percentage of CD4+ effector memory T cells was inversely associated with incident diabetes independent of subclinical inflammation, but CD4+ effector memory T-cell subsets affected the relationship between IL-6 and incident diabetes. Further studies are needed to confirm and investigate mechanisms by which T-cell immunity affects diabetes risk.

Cross sectional association between cytomegalovirus seropositivity, inflammation and cognitive impairment in elderly cancer survivors

PURPOSE

The higher prevalence of cognitive impairment/ dementia among cancer survivors is likely multifactorial. Since both exposures to cytomegalovirus (CMV) and inflammation are common among elderly cancer survivors, we evaluated their contribution towards dementia.

METHODS

Data from 1387 cancer survivors and 7004 participants without cancer in the 2016 wave of the Health and Retirement Study (HRS) was used in this study. Two inflammatory biomarkers, C-reactive protein (CRP) and neutrophil-lymphocyte ratio (NLR), were used to create an inflammation score. We used survey logistic regression adjusted for survey design parameters.

RESULTS

CMV seropositivity was not associated with cognitive impairment among cancer survivors (p = 0.2). In addition, inflammation was associated with elevated odds of cognitive impairment (OR = 2.2, 95% CI [1.2, 4.2]). Cancer survivors who were both CMV seropositive and had increased inflammation had the highest odds of cognitive impairment compared to those who were CMV seronegative and had low inflammation (OR = 3.8, 95% CI [1.5, 9.4]). The stratified analysis among cancer survivors showed this association was seen only among cancer survivors in whom the cancer was diagnosed within three years of measurement of inflammation score and CMV serostatus (OR = 18.5; 95% CI [6.1, 56.1]).

CONCLUSION

The CMV seropositivity and high inflammation was associated with higher cognitive impairment among cancer survivors. The stronger associations seen among cancer survivors diagnosed within the last three years suggest that strategies to reduce CMV activation and inflammation during or immediately after cancer treatment may be important in reducing the prevalence of cognitive impairment/ dementia among cancer survivors.