Reduced C3 Levels Link Dyslipidemia and Renal Involvement in Systemic Lupus Erythematosus

Background: Dyslipidemia is more frequently observed in systemic lupus erythematosus (SLE) patients with hypocomplementemia, suggesting potential connections between immune dysregulation and lipid metabolism. This study aims to explore the association between complement components and lipid profiles, and investigate the influence in organ involvement among SLE patients. Methods: A total of 935 patients diagnosed with SLE were enrolled and stratified based on their baseline lipid profiles. Logistic regression, stratified analyses and ROC curves analyses were employed to evaluate the predictive value of complements with other factors for dyslipidemia and organ involvement. Results: Among the 935 enrolled SLE patients, 527 (56.4%) were diagnosed with dyslipidemia. Patients in the dyslipidemia group exhibited higher erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and lower complement 3 (C3) levels compared to those without dyslipidemia. Lower C3 levels were independently associated with an increased risk of dyslipidemia (OR = 0.29, 95% CI: 0.18– 0.47, P < 0.0001) and renal involvement (OR = 0.21, 95% CI: 0.12– 0.37, P < 0.0001). This association of dyslipidemia were further strengthened in patients with C3 ≤ 0.7 g/L (OR = 0.08, 95% CI: 0.01– 0.48, P = 0.0061). In addition, a predictive model for dyslipidemia risk among SLE patients was developed. Using criteria of C3 (≤ 0.68 g/L) and ESR (≥ 33.65 mm/h), the model achieved 64.1% sensitivity, 74.7% specificity, and an AUC of 0.71 for dyslipidemia prediction. Conclusion: Reduced C3 levels serve as a significant independent risk factor for dyslipidemia and renal involvement. Furthermore, the combination of C3 and ESR enhances the identification of dyslipidemia.