Assessment of immune cell profiles among post-menopausal women in the Women's Health Initiative using DNA methylation-based methods.

BACKGROUND: Over the past decade, DNA methylation (DNAm)-based deconvolution methods that leverage cell-specific DNAm markers of immune cell types have been developed to provide accurate estimates of the proportions of leukocytes in peripheral blood. Immune cell phenotyping using DNAm markers, termed immunomethylomics or methylation cytometry, offers a solution for determining the body's immune cell landscape that does not require fresh blood and is scalable to large sample sizes. Despite significant advances in DNAm-based deconvolution, references at the population level are needed for clinical and research interpretation of these additional immune layers. Here we aim to provide some references for immune populations in a group of multi-ethnic post-menopausal American women. RESULTS: We applied DNAm-based deconvolution to a large sample of post-menopausal women enrolled in the Women's Health Initiative (baseline, N = 58) or the ancillary Long Life Study (WHI-LLS, N = 1237) to determine the reference ranges of 58 immune parameters, including proportions and absolute counts for 19 leukocyte subsets and 20 derived cell ratios. Participants were 50-94 years old at the time of blood draw, and N = 898 (69.3%) self-identified as White. Using linear regression models, we observed significant associations between age at blood draw and absolute counts and proportions of naïve B, memory CD4+, naïve CD4+, naïve CD8+, memory CD8+ memory, neutrophils, and natural killer cells. We also assessed the same immune profiles in a subset of paired longitudinal samples collected 14-18 years apart across N = 52 participants. Our results demonstrate high inter-individual variability in rates of change of leukocyte subsets over this time. And, when conducting paired t tests to test the difference in counts and proportions between the baseline visit and LLS visit, there were significant changes in naïve B, memory CD4+, naïve CD4+, naïve CD8+, memory CD8+ cells and neutrophils, similar to the results seen when analyzing the association with age in the entire cohort. CONCLUSIONS: Here, we show that derived cell counts largely reflect the immune profile associated with proportions and that these novel methods replicate the known immune profiles associated with age. Further, we demonstrate the value this methylation cytometry approach can add as a potential application in epidemiological studies.

Associations between perceived discrimination and immune cell composition in the Jackson Heart Study.

African American adults suffer disproportionately from several non-communicable and infectious diseases. Among numerous contributing factors, perceived discrimination is considered a stressor for members of historically marginalized groups that contributes to health risk, although biological pathways are incompletely understood. Previous studies have reported associations between stress and both an up-regulation of non-specific (innate) inflammation and down-regulation of specific (adaptive) immunity. While associations between perceived discrimination and markers of inflammation have been explored, it is unclear if this is part of an overall shift that also includes down-regulated adaptive immunity. Relying on a large cross-section of African American adults (n = 3,319) from the Jackson Heart Study (JHS) in Jackson, Mississippi, we tested whether perceived everyday and lifetime discrimination as well as perceived burden from lifetime discrimination were associated with counts of neutrophils (innate), monocytes (innate), lymphocytes (adaptive), and the neutrophil-to-lymphocyte ratio (NLR), derived from complete white blood cell counts with differential. In addition, DNA methylation (DNAm) was measured on the EPIC array in a sub-sample (n = 1,023) of participants, allowing estimation of CD4T, CD8T and B lymphocyte proportions. Unexpectedly, high lifetime discrimination compared to low was significantly associated with lower neutrophils (b : -0.14, [95% CI: -0.24, -0.04]) and a lower NLR (b : -0.15, [95% CI: -0.25, -0.05]) after controlling for confounders. However, high perceived burden from lifetime discrimination was significantly associated with higher neutrophils (b : 0.17, [95% CI: 0.05, 0.30]) and a higher NLR (b : 0.16, [95% CI: 0.03, 0.29]). High perceived burden was also associated with lower lymphocytes among older men, which our analysis suggested might have been attributable to differences in CD4T cells. These findings highlight immune function as a potentially important pathway linking perceived discrimination to health outcomes.