Emerging Biomarkers in Diabetic Kidney Disease: The Role of Serum Renalase and Fatty Acid Binding Proteins in T2DM Patients

Abstract

Background: Diabetic kidney disease (DKD) remains a major cause of end-stage renal disease, with current diagnostic methods often failing to detect damage in its early stages. This has led to an increased focus on novel biomarkers that can provide a more comprehensive view of the disease's progression. Renalase, a circulating enzyme primarily secreted by the kidneys, functions to metabolize catecholamines and possesses anti-inflammatory and anti-fibrotic properties. While its levels rise in DKD as a compensatory, protective response to systemic and renal stress, this elevation negatively correlates with kidney function, making it a potential biomarker for monitoring disease severity. The FABP family, particularly liver-type FABP (L-FABP) and adipocyte-type FABP (A-FABP), plays a crucial role in lipid metabolism. In DKD, lipid overload in the renal tubules leads to cellular injury and increased expression of L-FABP. The release of L-FABP into the urine serves as a highly sensitive indicator of early tubular damage, often preceding the onset of microalbuminuria. Similarly, elevated serum A-FABP levels are linked to increased inflammation and a higher risk of renal function decline. This paper examines the significance of two such protein families, renalase and fatty acid-binding proteins (FABPs), which are significantly increased in DKD

Methods: About 60 study participants were selected from the General Medicine OPD based on the age and gender matched depending on the on the inclusion and exclusion criteria. All the biochemical parameters were analysed by using biochemistry auto analyser and FABP-1and Renalase by sandwitch ELISA method. Statistical Analysis: Data analysis involved descriptive statistics, analysis of variance (ANOVA), Tukey HSD post hoc tests. We employed pearman’s correlation to examine relationships between relevant variables. The p value significant at <0.05.Finally, receiver operating characteristic (ROC) analysis was performed to evaluate the diagnostic performance of Renalase and FABP.

Results: Serum RNLS levels and FABP levels were significantly higher in DKD patients compared to T2DM and controls (0.042, 0.77 & 0.65), p < 0.01). Receiver operating characteristic curve analysis demonstrated the diagnostic value of RNLS and FABP in DKD is (1 (95% confidence interval (CI) = 0.70–0.82, p < 0.01)) and 0.77 (95% CI = 0.66–0.84, p < 0.01) respectively

Conclusion: The increased levels of renalase and FABPs in DKD highlight the complex interplay of compensatory and injurious mechanisms in the disease's pathogenesis. These proteins offer promising avenues for more effective early diagnosis and prognosis by providing insights into both systemic responses and specific cellular damage within the kidney.