Inducible nitric oxide synthase and systemic lupus erythematosus: a systematic review and meta-analysis

BACKGROUND: There is a growing body of evidences indicating iNOS has involved in the pathogenesis of SLE. However, the role of iNOS in SLE is inconsistency. This systematic review was designed to evaluate the association between iNOS and SLE. RESULTS: Six studies were included, reporting on a total of 277 patients with SLE. The meta-analysis showed that SLE patients had higher expression of iNOS at mRNA level than control subjects (SMD = 2.671, 95%CI = 0.446–4.897, z = 2.35, p = 0.019), and a similar trend was noted at the protein level (SMD = 3.602, 95%CI = 1.144–6.059, z = 2.87, p = 0.004) and positive rate of iNOS (OR = 9.515, 95%CI = 1.915–47.281, z = 2.76, p = 0.006) were significantly higher in SLE group compared with control group. No significant difference was observed on serum nitrite level between SLE patients and control subjects (SMD = 2.203, 95%CI = -0.386–4.793, z = 1.64, p = 0.095). The results did not modify from different sensitivity analysis, representing the robustness of this study. No significant publication bias was detected from Egger’s test. CONCLUSIONS: There was a positive correlation between increasing iNOS and SLE. However, the source of iNOS is unknown. Besides NO pathway, other pathways also should be considered. More prospective random studies are needed in order to certify our results.