Genetic variations of interleukin 32(rs28372698) and interleukin 37 (rs3811047), and their serum levels in systemic lupus erythematosus patients

Background

Systemic lupus erythematosus (SLE) is a complex autoimmune disease. The underlying pathogenesis still needs to be elucidated.

Aim of the work

To investigate interleukin-32 (IL-32) (rs28372698) and interleukin-37 (IL-37) (rs3811047) genetic variations, measure their serum levels in SLE patients, and evaluate their relation with disease parameters.

Patients and methods

This work included 46 SLE patients and 43 matched controls. The SLE disease activity index (SLEDAI) and SLE damage index (SDI) were recorded. Genetic variations were assessed by real-time polymerase chain reaction (RT-PCR), and serum levels of IL-32 and IL-37 were measured by enzyme-linked immune-sorbent assay (ELISA).

Results

The mean age of the patients was 29.2 ± 6.1 years, and the female: male ratio was 45:1. IL-37 genetic variation (rs3811047) GG was significantly more frequent in SLE patients (24/46,52.2 %) (p = 0.024), those with lupus nephritis (LN)(18/27,66.7 %) (p = 0.038), and active disease (15/21,68.2 %) (p = 0.002). The IL-37 G allele was significantly more represented in lupus patients (68/92,73.9 %)(p = 0.008), with IL-37 serum levels significantly increased in SLE patients (855.7 ± 465.4) compared to the control (504.1 ± 553.8) (p = 0.002). Although serum IL-32 was significantly higher in patients who received cyclophosphamide (CYC),and significantly correlated with total cholesterol, on regression analysis neither CYC nor cholesterol were significant factor for serum IL-32. The area under the curve for IL-37 serum levels to distinguish SLE patients from controls was 0.71, (CI 0.601–0.827; p = 0.001).

Conclusion

The IL-37 genetic variation (rs3811047) GG was significantly elevated in SLE, LN, and active patients. G allele was significantly more represented in lupus patients. IL-37 serum levels were significantly increased in SLE patients.