Urinary lipoxin A4 as a biomarker for systemic lupus erythematosus

Introduction Systemic lupus erythematosus (SLE) is an autoimmune disorder that has multiorgan involvement. The continuation of inflammation in lupus could be attributed to failure of the resolution process because of deficiency of potent endogenous proresolution-inducing molecules such as lipoxin A4 (LXA4), leading to progression and flares of lupus and lupus nephritis. Objective The aim of this study was to assess the levels of urinary LXA4 in SLE patients and in healthy controls, and to correlate them with various clinical and laboratory data as well as renal biopsy and disease activity indices (DAIs). Patients and methods A total of 40 adult female SLE patients were included in this study. Forty healthy women age-matched with SLE patients served as the control group. All patients were subjected to a full assessment of history, clinical examination, assessment of DAIs (SLEDAI and renal SLEDAI), and laboratory investigations including the urinary LXA4/creatinine ratio assessed by enzyme linked immunosorbent assay. Results Urinary LXA4/creatinine ratio levels were found to be significantly higher in all SLE patients compared with the healthy controls (P = 0.037). The median level of the urinary LXA4/creatinine ratio was lower in SLE patients with nephritis than in patients without nephritis (0.1 and 0.3 ng/ml, respectively), but with no statistical significance (P = 0.11). The urinary LXA4/creatinine ratio levels were found to be significantly lower in SLE patients with cardiovascular manifestations as well as those with neuropsychiatric manifestations (P = 0.009, 0.04 respectively). Conclusion This was a novel study that was carried out to assess the levels of urinary LXA4 in SLE patients. It showed that the urinary LXA4/creatinine ratio levels were significantly lower in SLE patients with cardiovascular and neuropsychiatric manifestations and nonsignificantly lower in patients with nephritis, suggesting that insufficiency of LXA4 in the human body may be responsible for major organ involvement in SLE patients. Accordingly, LXA4 is suggested to be an inflammatory biomarker not only for lupus nephritis but also for other systemic manifestations in SLE