SALIVARY AND URINARY METABOLOMICS STUDY IN IGA NEPHROPATHY PATIENTS

Abstract

Objective: Immunoglobulin A nephropathy (IgAN) is the most common form of glomerulonephritis worldwide with a strong autoimmune component. Metabolites will allow us to evaluate such diseases by analyzing body fluids. We aim to evaluate the disease from a different perspective including saliva and differences between healthy people and IgAN patients. And show the correlation between saliva and urine of the IgAN patients. Materials-Methods: This study was based on healthy controls and IgAN patients groups which presented Bezmialem Vakıf University. Stimulated salivary samples and spot urine samples were collected from both groups. Collected samples were processed to full metabolome analysis in Liquid Chromatography-Mass Spectrometry device. Results: 16 participants whose mean age was 54.31±6.651 for IgAN and 10 participants whose mean age were 41.46±6.009 for the healthycontrols were enrolled in this study. Metabolomic analysis identified 4 saliva and 19 urine metabolites that significantly dysregulated in IgAN patients (Figure 1 and Figure 2). The metabolic pathway analysis of saliva and urine samples showed several imparied pathways. Conclusion: Results showed N-Acetylneuraminic acid was dysregulated both in urine and saliva samples. N-Acetylneuraminic acid was significantly downregulated in saliva and upregulated in urine compared to the healthy controls (p=0,048729 and p=0,000941653). Review of the known literature suggests that this pattern contradicts the metabolomic results that belong to chronic kidney disease. So this pattern could be a possible marker that differentiates IgAN from other chronic kidney disease and healthy people. Also purine metabolism, glutamatergic synapse and GABAergic synapse which were impaired in saliva of IgAN patients, the metabolites that belong to these pathways which are Uric acid and L-glutamine were found downregulated in urine. Further studies with greater numbers of participants with multiple sample collections in different times will be beneficial to showing affected and changed metabolites and pathways as the course of the disease changes. Keywords: Immunoglobulin A Nephropathy, metabolomics, salivary metabolomics, urinary metabolomics.