Abstract MP05: The Impact Of Neighborhood Social Environment On Natural Killer Cells In A Community-based Cohort Of African American Women
Authors: Baez Andrew S , Baumer Yvonne , Gray Veronica , Neally Sam , Gutierrez-Huerta Cristhian , Turner Briana , Mitchell Valerie , Collins Billy , Powell-Wiley Tiffany M 
Published: April 2022

Introduction:
Chronic exposure to environmental stressors is associated with racial and ethnic disparities in cardiovascular disease (CVD) risk factors. African American (AA) women are at highest risk for obesity and subsequent CVD development. Obesity as a CVD risk factor and psychosocial stressors have been associated with altered Natural Killer (NK) cell distribution and function. Less is known about how perceived and objective neighborhood social environment relates to NK cell distribution and function.

Hypothesis:
More favorable neighborhood social environment would associate with a greater number and more functional NK cell population.

Methods:
We recruited 40 AA women from a Washington, DC community-based cohort and determined the NK cell profile using flow cytometry according to their CD3/CD56 expression on the cell surface. Neighborhood social environment was measured by neighborhood environment (NE) perceptions and objective neighborhood deprivation index (NDI). NE perceptions were measured using validated questionnaires to calculate overall NE perceptions, perceived neighborhood violence, physical/social environment, social cohesion, and safety (higher score=more favorable perceptions). NDI was measured using U.S. Census data on census-tract level features (i.e., housing characteristics, education, income, poverty) where higher NDI=lower NE socioeconomic level. Multivariable regression models were used to determine associations between neighborhood social environment and NK cell number. Additionally, regression models were adjusted for Atherosclerotic Cardiovascular Disease (ASCVD) risk and BMI, unless otherwise specified.

Results:
Among this community-based cohort of AA women (N=40 mean age 58.8 ±12.0; BMI 34.2 ±6.9), overall NE perceptions were associated with overall NK cell numbers before and after adjustments for ASCVD and BMI (β=0.48, p=0.007, β=0.50, p=0.004). Perceived lack of violence was associated with increased NK cell number (β=0.38, p=0.04) even after the adjustment for ASCVD and BMI (β=0.39, p=0.03). Similar trends were observed with social cohesion and NK cells (β=0.32, p=0.06) and with perceived favorable physical/social environment and NK cells (β=0.34, p=0.07). In contrast, we found that safety did not show any significant association with NK cell numbers (β=0.28, p=0.13). Finally, NDI as an objective measure of neighborhood SES did not associate with NK cell numbers (β=-0.05, p=0.74).

Conclusion:
Together, our data suggest that perceived neighborhood social environment associates with NK cell numbers, while objective measures do not. These findings suggest that changes in NK cell populations may be driven by perceived social environment factors and could alter CV risk. Future studies are needed to determine the potential impact of social environment stressors on NK cell subtypes, receptor expression, and function.