Discovery and longitudinal assesment of candidate biomarkers of development and progression of nephropathy in Fabry disease

Fabry disease (FD) is a clinically heterogeneous disease and factors that influence the clinical course are not fully known. Nephropathy contributes significantly to the morbidity and mortality of FD. Therefore, this study focuses on the discovery and assessment of biomarkers influencing the development and progression of nephropathy in Fabry patients through longitudinal analysis of samples collected over the past decade. Disease-causing GLA gene variants are associated with clinical manifestations of FD, but the influence of additional genetic factors is not fully known and is proposed to be investigated in this study. Transcriptome studies evaluating mRNA profiles enable us to bridge the gap between genetic factors and functional molecules in the cells. Dysregulated gene expression was observed in chronic kidney disease but not yet in FD. Therefore, the proposed longitudinal evaluation of mRNA profiles is an innovative approach that may allow the identification of biological pathways involved in the development and progression of Fabry nephropathy. Moreover, this would be a continuation of our previous work, as we have already identified microRNA species known to be dysregulated in Fabry patients with stable and/or progressive nephropathy, but whose mRNA targets remain to be assessed. Oxidative stress affects telomere length and thus premature cell aging and contributes to the progression of renal dysfunction. We have already demonstrated shorter telomeres lengths in a small FD cohort. Therefore, further assessment of the dynamics of telomere attrition, in addition to the chronological assessment of biochemical markers of senescence, oxidative stress, and kidney injury in patients with a different pace of disease progression would contribute to a better understanding of the role of cell aging in FD on the biochemical level. Targeted metabolomic studies have identified plasma metabolites that are differently expressed in FD, whereas studies investigating changes in the metabolome during the progression of Fabry nephropathy, as proposed in this project, have not yet been performed. The proposed protocol will include FD patients with different progression of nephropathy, namely approximately 40 Slovenian patients, their age- and sex-matched control subjects, and at least 150 foreign patients. In the clinical part, we will investigate the clinical characteristics of the patients in the last decade, with an emphasis on nephropathy. In the experimental part of the study, we will perform NGS-based genomic sequencing of the entire cohort. In chronological blood and/or urine samples from Slovenian Fabry patients and controls we will investigate a) expression of mRNAs with NGS, b) telomere length attrition with qPCR, biomarkers of cellular senescence, oxidative stress, and kidney damage with ELISA or LC/MS-MS, and c) NMR-based metabolome profiles. The final part will focus on the construction of a predictive model integrating all the data obtained in the experimental part of the study, with the main aim of elucidating the collective value of the analysed biomarkers in the development and progression of Fabry nephropathy. We believe that the longitudinal design of the study (10 years) and the comprehensive state-of-the-art study approach targeting different types of biomarkers are the most original points of the proposal and should provide scientifically valuable results. We will combine genomic data with data from other modalities such as transcriptomics and metabolomics, to uncover specific pathways involved in the pathophysiological process underlying the Fabry nephropathy. We expect to identify molecular processes and associated biomarkers that influence the development and rate of progression of Fabry nephropathy. In the future, understanding these factors may provide the basis for early identification of patients at risk and may create novel options for effective treatment, as well as for slowing or even preventing its development.