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Patients with systemic autoimmune diseases such as systemic lupus erythematosus (SLE) have an increased risk of suffering a myocardial infarction (MI), and are also more likely to die, develop heart failure, or suffer a second cardiac event than patients without an autoimmune disease. SLE primarily affects women and is characterized by autoreactive T and B lymphocytes that lead to widespread production of autoantibodies to a variety of nuclear and cytoplasmic antigens. Autoantibody-antigen immune complexes deposit in tissues and activate downstream inflammatory pathways leading to end-organ damage to tissues such as the heart, lungs, kidneys, and vasculature. However, the mechanisms whereby SLE disease may exacerbate MI and lead to poor outcomes in autoimmune patients is not well understood. The purpose of the present study was to test the hypothesis that SLE disease pathogenesis contributes to worsened outcomes after MI because of systemic inflammatory processes taking place. To test this hypothesis, saline (control, n=7) and pristane-treated (SLE, n=8) C57BL/6 mice were subjected to permanent coronary artery ligation (MI) and studied at 7 days post MI. Left ventricular (LV) function was examined at baseline (D0) and D7 using echocardiography (VEVO 3100). Control and SLE mice had similar LV parameters at baseline, but SLE mice had significantly more wall thinning in the infarct area (Control: 0.54±0.05 vs. SLE: 0.36±0.03 mm, p=0.005) as well as in the remote area (Control: 0.59±0.07 vs. SLE: 0.38±0.03 mm, p=0.01). SLE mice also displayed increased LV dilation (Control: 61.7±5.3 vs. SLE: 78.9±3.8 μL, p=0.02) at 7 days post MI. Ejection fraction was significantly lower in SLE mice as well (Control: 26.3±2.0% vs. 19.0±2.5%, p=0.045). We examined expression of inflammatory cytokines and collagen subunit genes in infarcted heart tissue using qPCR. SLE mice had increased expression of several inflammatory cytokines, including IL-6 and IL-18, while other cytokines such as IL-1β and TNF-α were not significantly different between the groups. In addition, SLE mice had decreased expression of the Col1a1, which encodes the alpha subunit of Type I Collagen, and Cd31, an endothelial cell marker, suggesting impairment of scar formation and angiogenesis post MI in SLE mice. Flow cytometric analyses of infiltrating LV immune cells showed increased total CD45 + cells in the infarcted area of SLE mice (Control: 10.6±1.2% vs. SLE: 13.8±0.6%, p=0.03), and a trend for an increase in CD45R + B cells (Control: 7.5±1.1% vs. SLE: 12.5±2.1%, p=0.05). Taken together, these data indicate that SLE disease impacted recovery post MI, possibly due to increased B cell infiltration in the heart. Future studies will assess outcomes at later time points and also examine the progression of renal injury post MI. NIH/NHLBI R00 HL146888 and U54 HL169191 to Taylor NHLBI R01 HL166737 and AHA CDA856365 to Mouton NIGMS P20 GM104357 and P30 GM149404 to Department of Physiology and Biophysics. This is the full abstract presented at the American Physiology Summit 2024 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.
Taylor et al. (Wed,) studied this question.