Early life stress (ELS) promotes B cell expansion and aortic pathology in a mouse model of systemic lupus erythematosus (SLE)
Authors: Kellum Cailin , Colson Jack , Kelly Gillian , Pollock Jennifer 
Published: May 2023

SLE is an autoimmune disease that primarily affects young women and is associated with high rates of cardiovascular disease (CVD). Exposure to ELS (adversity in childhood such as verbal and physical abuse and/or familial dysfunction) is an independent risk factor for CVD and SLE. ELS heightens the risk of developing SLE and SLE patient-reported disease activity, however the underlying mechanism is unclear. We previously showed in a mouse model of ELS, maternal separation with early weaning (MSEW), that mice with pristane-induced SLE develop autoantibodies and increased aortic stiffness earlier in disease progression compared to normally reared (NR) SLE mice. We hypothesized that disease acceleration in MSEW+SLE mice compared to NR+SLE mice is associated with an expansion of B-cells and aortic structural changes. The pristane-induced model of SLE uses an intraperitoneal injection (i.p.) to induce SLE-like symptoms in female mice. The MSEW protocol separates pups from the dam 4h/day (postnatal, PD 2 to 5) and 8h/day (PD 6 to 16) with weaning at PD17. NR litters are weaned at PD21. At 6-8 weeks of age, female mice were randomly assigned to control (CON) or SLE groups: CON received an i.p. PBS injection, while NR+SLE and MSEW+SLE received an i.p. pristane injection. Spleen and thymus were weighed and collected for B-cell subset analysis with flow cytometry and aorta were dissected for histological assessments. At 4 months-post pristane, spleen weights did not differ between groups, however, we observed that MSEW+SLE mice had significantly larger thymus/body weight (BW) compared to CON and NR+SLE mice (p=0.0004 F=7.5 n=4). At 7 months post-pristane or PBS injection, MSEW+SLE mice and NR+SLE mice had significantly higher splenic weights/BW compared to CON mice (p=0.03 F=4.36, n=6) as expected. Using flow cytometry, we found increased thymic %age of CD19+ B-cells in both NR+SLE and MSEW+SLE compared to CON (p<0.0001 F=57.33, n=8,4,4), whereas we found similar %age of CD19+ B-cells in the aorta or spleen of mice in all groups. MSEW+SLE mice had increased germinal center B-cells compared to CON (CON: 0.77%, NR+SLE: 6.0%, MSEW+SLE 7.4%, p=0.008 F=7.08 n=8,4,4) while NR+SLE mice had increased plasma cells compared to CON (CON: 0.08%, NR+SLE: 1.3%, MSEW+SLE 0.68%, p=0.015 F=5.92 n=8,4,4). At 7 months post-pristane, MSEW+SLE mice had significantly greater aortic wall thickness (um) compared to NR+SLE and NR+CON mice (p=0.008 F=11.99, n=3,3,3), however, aortic collagen content (picrosirius red) was similar. These data suggest a difference in B-cell subset expansion and aortic structural changes may contribute to the MSEW driven acceleration of disease activity. Understanding how ELS accelerates autoimmunity and CVD risk is crucial to preventing worsened outcomes in vulnerable populations of individuals exposed to ELS with SLE. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.