#3564 DIAGNOSTIC AND PROGNOSTIC SIGNIFICANCE OF INTERLEUKIN-6 IN LUPUS NEPHRITIS
Authors: Kar Deba , Mohanty Bishwa 
Published: June 2023

Abstract

Background and Aims
Lupus nephritis is a frequent and potentially serious complication of SLE. The present study is aimed to evaluate the usefulness of urinary IL-6 as a non-invasive diagnostic & prognostic biomarkers of disease activity in LN.

Method
The study was done in IMS and Sum hospital, Bhubaneswar, India from January, 2018 to July 2022. The study included 20 healthy controls and 32 patients of SLE diagnosed based of Systemic Lupus International Collaborating Clinic (SLICC) criteria, who presented with renal involvement. The exclusion criteria was inability to obtain informed consent and SLE patients without renal involvement. Urinary IL-6 levels were assessed in patients before initiation of therapy and in controls by quantitative sandwich EASIA technique using human IL-6 EASIA kit (DIA Source Belgium). All patients underwent ultrasound guided renal biopsy and the results were classified according to the ISN/RPS classification of LN. Treatment was started in all patients according to class of LN as per KDIGO guidelines. Urinary IL-6 levels were again assessed in all patients after 6 months of induction phase treatment.

Results
In our 32 patients, female to male ratio was 7:1 with a mean age of 28.68 ± 9.28 years. In our study, ANA was positive in 96.8%, anti-dsDNA Ab in 78%, C3 was low in 78% & C4 was low in 72% of LN patients. Based on renal biopsy findings, there were 2 cases of Class II LN, 6 cases of Class III LN, 19 cases of Class IV LN and 5 cases of Class V LN. In our study, patients with LN have significantly higher urinary IL-6 levels (301.58 ± 483.96 pg/ml) as compared to 20 healthy controls (4.7±2.282 pg/ml) with a p-value = 0.001. The mean urinary IL-6 levels in different ISN/RPS classes of LN patients based on renal biopsy showed a statistically significant difference between different classes (p-value = 0.005). Highest values of urinary IL-6 (475.126 ± 580.90 pg/ml) was seen in Class-IV LN which is most active form of LN and lowest values (28.28 ±7.30pg/ml) were seen in Class-II LN. In our study, a significant correlation was found between serum creatinine & presence of active urinary sediment with urinary IL-6 levels but there was no correlation between 24 hour urinary protein with urinary IL-6 levels in patients of LN (p value = 0.799). In our study 2 patients (6.25%) died, 3 patients (9.37%) lost follow up, 16 patients (50%) achieved complete remission, 8 patients (25%) achieved partial remission and 3 patients (9.37%) did not show any improvement after 6 months treatment. Urinary IL-6 levels were near normal among 12 patients (75%) out of 16 patients who achieved remission after 6 months of induction treatment (p-value = 0.001). Urinary IL-6 levels remained elevated in all 8 patients (100%) who achieved partial remission (p-value = 0.028, and also remained elevated in all 3 patients who had no remission at all (p-value = 0.109).

Conclusion
Urinary IL-6 may provide a simple non-invasive potential biomarker of disease activity of renal involvement in patients with SLE and may be used to monitor therapy.