Background: Systemic lupus erythematosus (SLE) is an autoimmune disorder affecting various organ systems with unknown etiology. Interleukin-6 (IL-6) and interferon-alpha (IFN-α) have been shown to have a major role in disease pathogenesis, and they correlate with SLE disease activity, but reports in the literature are conflicting. The present study aims to investigate the significance of IL-6 and IFN-α levels in SLE pathogenesis in an eastern Indian cohort.
Material and methods: 70 SLE patients fulfilled SLICC 2012 criteria, and 40 age- and gender-matched healthy controls (HC) were enrolled. Baseline characteristics along with disease activity were recorded for all patients. Levels of IL-6 and IFN-α were measured by using ELISA. For the meta-analysis, published articles were searched through different databases. Two independent researchers extracted data, and the meta-analysis was performed with CMA v3.1.
Results: The plasma levels of IL-6 and IFN-α in SLE patients were significantly elevated compared to HC (IL-6: p < .0001, IFN-α: p = 0.01). SLEDAI score correlated positively with plasma IL-6 (p < .0001, r = 0.46) and IFN-α levels (p < .0001; r = 0.47). Meta-analysis of previous reports, including our case-control data, revealed higher IL-6 (p < .0001) and IFN-α (p = .005) in SLE patients compared to HC. Furthermore, IL-6 (p < .0001, r = 0.526) and IFN-α (p < .0001; r = 0.371) levels positively correlated with the disease activity.
Conclusion: IL-6 and IFN-α levels are elevated in SLE and they correlate with disease activity. Further studies with a larger sample size in different populations are required to validate our findings.
Keywords: Interferon-alpha; Interleukin-6; SLE disease activity scores; Systemic lupus erythematosus; meta-analysis.