Early Life Stress (ELS) Accelerates Autoimmunity and Synergistically Increases Risk for Cardiovascular Disease (CVD) in the Pristane‐Induced Model of Systemic Lupus Erythematosus (SLE) in Mice

ELS is defined as exposure to childhood adversity such as maltreatment (e.g., verbal and physical abuse), sexual abuse, and household dysfunction occurring prior to age 18. ELS is associated with increased risk of CVD and poorer health outcomes earlier in adulthood. SLE is an autoimmune disease with high CVD burden and influenced by environmental factors including psychosocial stress such as ELS. We hypothesized that a mouse model of ELS, maternal separation with early weaning, MSEW, would develop autoimmunity in response to the pristane-induced model of SLE earlier and at higher levels than normally reared (NR) SLE mice. We further hypothesized that MSEW+SLE mice would have earlier onset of increased CVD risk determined by aortic stiffness and vascular dysfunction. MSEW entails separating pups from the dam 4h/day (postnatal, PD 2 to 5) and 8h/day (PD 6 to 16) followed by weaning at PD17. NR litters remain with the dam and are weaned at PD21. The pristane-induced model of SLE uses a single intraperitoneal (i.p.) injection to induce SLE-like symptoms in female mice that include autoantibody production, vascular dysfunction, kidney damage, and increased blood pressure. At 6-8 weeks of age, female mice were grouped accordingly: NR control (NR+CON) received an i.p. saline injection, while NR+SLE and MSEW+SLE received an i.p. pristane injection. To measure autoimmunity, anti-Smith autoantibodies associated with the pristane model and IgG antibodies were measured at 4 months post-pristane injection. MSEW+SLE mice developed significantly higher levels of anti-Smith autoantibodies while NR+SLE mice had similar levels to NR+CON mice (total arbitrary units; MSEW+SLE: 2.7, NR+SLE: 1.4, NR+CON:1.5, p=0.04). At five months post-pristane injection, MSEW+SLE and NR+SLE mice had similar levels of anti-Smith autoantibody levels (p=0.76). Similarly, at 4 months post-pristane injection Total Igg was increased in MSEW SLE animals compared to N+CON, but not in NR+SLE mice(OD 450; MSEW+SLE: 0.72, NR+SLE: 0.47, NR+CON:0.24, p=0.01). Aortic stiffness (increased pulse wave velocity, PWV) is a CVD risk marker and was assessed at 4 months post-pristane injection. PWV was significantly increased in MSEW+SLE mice (mm/sec; NR+CON: 1.5, NR+SLE: 1.5, MSEW+SLE 2.7, p=<0.0001). To assess aortic dysfunction, concentration response curves to phenylephrine (PE)-mediated constriction and acetylcholine (Ach)-mediated relaxation were completed from MSEW+SLE and NR+SLE mice at 7 months post-pristane injection. MSEW+SLE mice showed increased sensitivity to PE (log[PE], M; MSEW+SLE: -6.5, NR+SLE: -6.11, p=0.02), but no differences in Ach relaxation were observed. These results show that MSEW mice exposed to the environmental trigger for SLE, pristane, develop autoimmunity earlier and to a higher level as well as increased aortic stiffness compared to NR+SLE mice. This mouse model of ELS and SLE will allow in-depth studies to understand the ELS-specific mechanisms driving early development of autoimmunity and CVD risk. In conclusion, ELS accelerates autoimmunity and is associated with CVD risk which models the impact of ELS on humans with SLE.