Serum levels of Interleukin-2 in a cohort of Egyptian systemic lupus erythematosus patients with glomerulonephritis

Abstract

Summary Systemic lupus erythematosus (SLE) is a multisystem autoimmune disorder of connective tissue characterized by remissions and flares, and highly variable clinical presentation, disease course, and prognosis. Lupus nephritis (LN) is a serious potential feature of systemic lupus erythematous (SLE) due to deposition of immune complexes in the kidneys. Interleukin-2 (IL-2), a type of cytokine predominantly secreted by activated T cells and represents a key player in the cell-mediated immune response. Impaired IL-2 production by T cells has been confirmed in autoimmune conditions such as lupus-prone mice models and SLE patients. The aim of this work was to evaluate the relationship between serum Interleukin-2(IL-2) level and renal involvement in the Systemic lupus erythematosus (SLE) patients. This cross-sectional study has been conducted on 60 Egyptian patients with SLE fulfilling 2012 SLICC classification criteria for systemic lupus erythematous. All patients were subjected to detailed medical history taking and full clinical examination and rheumatological examination for clinical evaluation of lupus, assessment of SLE activity according to SLEDAI index, laboratory investigations including CBC, ESR, CRP, BUN, serum creatinine, urine analysis, protein creatinine ratio, ANA, anti-dsDNA antibodies and serum IL-2 level by ELISA. All data were collected, tabulated, and statistically analysed. The patients were subdivided into 2 groups, group 1, included 30 SLE patients with nephritis and group 2 included 30 SLE patients without nephritis, after exclusion of patients less than 18 years old, diabetic patients and those with other autoimmune diseases. Our study included 56 female patients (93.3%) and 4 male patients (6.7%), their ages ranged from 19 to 58 years, the with median disease duration was 4 (0.25-24). According to Parameters of disease activity of studied groups, the commonest presenting clinical feature in group1, was proteinuria (100%) while it was arthritis (50%) in group2 Regarding laboratory investigations among studied groups: serum creatinine was statistically significant higher in (group 1) 1.15 mg/dl ranged from 0.5 to 3.7 mg/dl as compared to 0.7 mg/dl ranged from 0.1 to 0.9 mg/dl in group 2 (p≤0.001), protein creatinine ratio (p/c ratio) was statistically significant higher in (group 1)1.10 ranged from 0.27 to 8.6 as compared to 0.11 ranged from 0.04 to 0.19 in (group 2)(p≤0.001) on the other hand no statistically significant difference was found between the 2 studied groups regarding the remaining studied parameters (p > 0.05) Regarding Immune data among the studied groups, there was statistically insignificant difference (p > 0.05) as regards the presence or absence of ANA and Anti-ds-DNA. Regarding the drug history, most of our patients in (Group1) received steroids (93%), (100%) received Immunosuppressive drugs, (30%) of them received azathioprine, (13%) received mycophenolate and (57%) received cyclophosphamide, (93%) received HCQ, and (13%) received NSAIDs but in (Group2) all patients received steroids(100%), only (60%) received Immunosuppressive drugs, (43%)of them received azathioprine, (10%) received mycophenolate and (7%) received cyclophosphamide, (80%) received HCQ, and (20%) received NSAIDs. Regarding Renal biopsy, it was done in group 1 and the commonest pathological type was Class II (56.6%). Regarding SLEDAI score and SLE disease activity between the two studied groups, there was statistically insignificant difference (p > 0.05). Regarding serum Interleukin-2 levels between the two groups, the median Interleukin-2 level was significantly lower in (group 1) 25.5 ng/L ranged from 5 to 90 ng/L than in (group 2) 53.5 ng/L ranged from 29 to165 ng/L with highly statistically significant difference (p≤0.001). There was statistically highly significant negative correlation between serum IL-2 and serum creatinine (r= -0.494 p≤0.001) and between serum IL-2 and protein/creatinine ratio (r=-0.512 p≤0.001), but no correlation was found between IL-2 and other variables (p > 0.05). Although there was no relationship between SLE disease activity and serum IL-2; we noticed that the level of serum IL-2 was higher with mild SLE disease activity ranged from 45 to 60 ng/L followed by moderate activity ranged from 15 to135 ng/L and the lower level was associated with high activity ranged from 5-165 ng/L. According to the study we may predict the occurrence of lupus nephritis by measuring serum interleukin-2 as we found that decreased serum interleukin-2 had an independent effect on increasing probability of occurrence of nephritis in SLE patients.