miR-155-3p in Systemic Lupus Erythematosus: Association with Immune Activation and Renal-Related Parameters

Systemic lupus erythematosus (SLE) is an autoimmune illness that affects multiple organs, causes hematological abnormalities, and alters immunological regulation. Identifying reliable biomarkers is critical for improving the diagnosis and monitoring of disease activity. This study aimed to evaluate clinical, biochemical, immunological, and molecular alterations in SLE patients compared with healthy controls, with a focus on the exploratory discrimination of whole-blood miRNA expression and conventional serological markers. A total of 100 SLE patients and 50 age-and gender-matched healthy controls were evaluated. Hematological, biochemical, and immunological markers were examined with miR-21-5p and miR-155-3p expression. Clinical relevance was determined using correlation analyses and ROC curve evaluations. SLE patients had significantly lower hemoglobin, WBCs, and platelets compared to controls (p < 0.001). Inflammatory indicators, such as CRP and ESR, were significantly higher (p < 0.001). Immunological testing showed significant increases in ANA, anti-dsDNA, and anti-Smith antibodies, as well as decreased complement (C3, C4) levels (all p < 0.001). miR-155-3p was considerably elevated in SLE patients and linked with anti-Smith antibodies and creatinine (p < 0.05), but miR-21-5p had no diagnostic significance. ROC analysis showed excellent diagnostic performance for ANA (AUC = 0.992) and anti-dsDNA (AUC = 0.973), with good accuracy for miR-155-3p (AUC = 0.813, p < 0.001). SLE patients have significant hematological, immunological, and renal changes. Among molecular indicators, miR-155-3p is associated with immune activation and selected renal-related laboratory parameters, including serum creatinine, without implying definitive renal involvement, indicating its potential as a complementary biomarker. These findings suggest that miR-155-3p may serve as an exploratory complementary biomarker alongside conventional serological markers; however, its incremental diagnostic value requires validation using multivariable diagnostic models in prospective studies.