Exostosin 1 and 2 protein markers predict prognosis of membranous lupus nephritis,finds study

It is well documented that in patients with secondary (autoimmune) membranous nephropathy, two novel proteins, Exostosin 1 and Exostosin 2 (EXT1/EXT2), are potential disease antigens, biomarkers, or both. So researchers aimed to validate the EXT1/EXT2 findings in a large cohort of membranous lupus nephritis.

The study was conducted as a retrospective cohort study of patients with membranous lupus nephritis, and performed immunohistochemistry studies on the kidney biopsy specimens against EXT1 and EXT2. Clinicopathologic features and outcomes of EXT1/EXT2-positive versus EXT1/EXT2-negative patients were compared.

Results put forth some interesting facts.

• The  study cohort included 374 biopsy-proven membranous lupus nephritis cases, of which 122 (32.6%) were EXT1/EXT2-positive and 252 (67.4%) were EXT1/EXT2-negative.
• EXT1/EXT2-positive patients were significantly younger (P=0.01), had significantly lower serum creatinine levels (P=0.02), were significantly more likely to present with proteinuria ≥3.5 g/24 h (P=0.009), and had significantly less chronicity features (glomerulosclerosis, P=0.001 or interstitial fibrosis and tubular atrophy, P<0.001) on kidney biopsy.
• Clinical follow-up data were available for 160 patients, of which 64 (40%) biopsy results were EXT1/EXT2-positive and 96 (60%) were EXT1/EXT2-negative.
• The proportion of patients with class 3/4 lupus nephritis coexisting with membranous lupus nephritis was not different between the EXT1/EXT2-positive and EXT1/EXT2-negative groups (25.0% versus 32.3%; P=0.32).
• The patients who were EXT1/EXT2-negative evolved to ESKD faster and more frequently compared with EXT1/EXT2-positive patients (18.8% versus 3.1%; P=0.003).

Observing the results, the team concluded that , "The extent of chronic changes, including global glomerulosclerosis and tubular atrophy and interstitial fibrosis, in EXT1/EXT2-positive LMN are less compared with EXT1/EXT2-negative LMN. EXT1/EXT2-positive LMN rarely progress into ESKD, compared with EXT1/EXT2-negative LMN. These findings have significant bearing when considering the high burden of SLE in worldwide. Furthermore, the mortality rate is increased to approximately 2.6-fold in SLE, and the risk of mortality is the highest in patients with kidney disease. LN is the most common renal manifestation in SLE: almost 10% of the patients will develop ESKD, and 20% of LN biopsies show LMN with or without concurrent class 3/4 LMN."

For full article follow the link: https://doi.org/10.1681/ASN.2020081181

Source: Journal of American Society of Nephrology