T-helper type 1 bias in healthy people is associated with cytomegalovirus serology and atherosclerosis: the Multi-Ethnic Study of Atherosclerosis

Abstract

Background: Although T-helper type 1 (Th1) cells are considered important in atherosclerosis, the relationships between Th1 and Th2 cells and atherosclerosis have not been examined in population-based studies.

Methods and results: We measured Th cells as a percentage of lymphocytes by flow cytometry using CD4 staining (%CD4) in 917 participants of the Multi-Ethnic Study of Atherosclerosis. We also measured interferon gamma-positive and interleukin-4-positive CD4(+) cells, representing Th1 and Th2 subpopulations (%Th1 and %Th2), respectively. We found that %CD4 was 1.5% lower per 10 years of age (P<0.0001). Whites had higher %CD4 and lower %Th1 and %Th2 values than other race/ethnic groups. Body mass index (BMI) and blood pressure were associated with %CD4, but no traditional cardiovascular disease (CVD) risk factors were associated with %Th1 or %Th2. In multivariable models, the major independent variable associated with %Th1 was cytomegalovirus (CMV) antibody titer, with minor contributions from age, sex, seasonality, and interleukin-6. In models with coronary artery calcification level as the outcome, significant independent variables included age, sex, smoking status, and %Th1 (β=0.25; P ≤ 0.01). Both %Th1 and %Th2 were associated with common carotid intimal media thickness (β=0.02 and -0.02, respectively; both P<0.05), as were age, sex, race/ethnicity, blood pressure, and BMI.

Conclusions: Th1 bias is associated with subclinical atherosclerosis in a multiethnic population. The main Th1 correlate was CMV infectious burden. These findings are consistent with a role of Th1 cells in atherosclerosis and suggest the importance of prospective studies of T-helper cell biasing in CVD.

Keywords: T‐helper cell; atherosclerosis; epidemiology; immunology; inflammation.

Figure 1.

Linear regression analyses of cellular measurements in fresh whole blood versus 24‐hour postdraw samples. The x axis represents values from freshly processed whole blood, and the y axis represents values from 24‐hour postdraw processing of whole blood. A, %CD4⁺ cells from peripheral blood mononuclear cells (PBMCs); B, %Th1 cells; C, log %Th2 cells.

Figure 2.

CD4, Th1, and Th2 flow‐cytometry gating strategies. The lymphocyte population is gated based on forward (y axis) and side (x axis) scatter plots using a fluorescently labeled sample (D) compared with an isotype control (A). Th1 cells are identified as those cells that are CD4⁺ (y axis) and IFN‐γ⁺ (x axis) (E) when compared with an isotype control (B). Th2 cells are identified as those cells that are CD4⁺ (y axis) and IL‐4⁺ (x axis) (F) compared with an isotype control (C). FSC indicates forward scatter; SSC, side scatter; FITC IFNg, fluorescein isothiocyanate‐conjugated anti‐IFN‐γ; PE IL4, R‐phycoerythrin‐conjugated anti‐IL‐4; IFN‐γ, interferon gamma.

Figure 3.

Distributions of cell phenotypes in Multi‐Ethnic Study of Atherosclerosis (MESA)–Inflammation. y Axis, count; x axis, value. A, %CD4; B, %Th1; C, %Th2.

Figure 4.

Distribution of %Th1 cells by category of CMV antibody titer. Mean (SEM) values of %Th1 cells are shown by category of CMV antibody titer. CMV categories were defined as 0.0 ELISA units (EU)/mL, 0.1 to 99.9 EU/mL, 100 to 199.9 EU/mL, and 200 to 299.9 EU/mL. CMV indicates cytomegalovirus; SEM, standard error of the mean.