Background: Fabry disease (FD) is an X-linked lysosomal storage disorder caused by disease-causing variants in the GLA gene, leading to deficient activity of the enzyme α-galactosidase A, glycosphingolipid accumulation, and the development of a clinical picture. Fabry nephropathy is a complication of FB that contributes significantly to morbidity and mortality, but the pathophysiologic processes of Fabry nephropathy are not yet fully understood. Early detection of Fabry nephropathy is currently a challenge as only late biomarkers of nephropathy are available in clinical practice.
Aim: Identification of epigenetic, genetic and biochemical biomarkers for the development and progression of Fabry nephropathy.
Methods: We included 39 Slovenian patients managed at the Center for Diagnosis and Treatment of Fabry Disease and 261 foreign patients. In addition, 35 age- and sex-matched control subjects were enrolled. We also included longitudinal samples from Slovenian and Swiss patients collected over a 10-year period during regular annual examinations. Urinary extracellular vesicles were isolated by size exclusion chromatography followed by RNA extraction. The expression of microRNA (miRNA) was determined by quantitative PCR. DNA was isolated from whole blood. The relative leukocyte telomere length (LTL) was determined by monochromatic multiplex quantitative PCR. Urinary oxidative stress markers were determined by ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Genetic variants were determined by whole-exome sequencing.
Results: We identified five miRNAs isolated from urinary extracellular vesicles with altered expression. The expression of miR-21-5p and miR-222-3p was statistically significantly higher in patients with stable kidney function and in patients with progressive nephropathy compared to control subjects. The expression of miR-30a-5p, miR-10b-5p and miR-204-5p was lower in the group of patients with progressive nephropathy, while a decrease in miR-204-5p expression was observed in the longitudinal samples. Some of the identified hub genes, which are regulated by deregulated miRNAs, have already been associated with kidney impairment in other kidney diseases. Enrichment analysis revealed that several signaling pathways involved in the pathophysiology of FD were enriched. We found no differences in LTL between Fabry patients and control subjects. However, there was a statistically significant difference in LTL between male patients and their control subjects. In both cross-sectional and longitudinal studies, we found no association between LTL and advanced organ involvement and/or the presence and number of late complications in Fabry patients (which include nephropathy, left ventricular hypertrophy and stroke). LTL was also not associated with the presence of nephropathy. Urinary 8-hydroxy-2'-deoxyguanosine and malondialdehyde levels were not associated with LTL and did not differ between patients and control subjects or between patients with different kidney functions. We also identified the variant rs749735949 in the coding region of the FAT1 gene, which was associated with progressive nephropathy. The odds ratio was 14.9 (95% confidence interval = 1.8–685.8), suggesting that carriers of this variant have an approximately 15-fold increased odds of developing progressive nephropathy.
Conclusion: Our study identified epigenetic and genetic biomarkers associated with the development and progression of Fabry nephropathy. Deregulated miRNAs such as miR-21-5p, miR-222-3p, miR-30a-5p, miR-10b-5p and miR-204-5p as well as the genetic variant rs749735949 in the FAT1 gene, which increases the odds of progressive nephropathy, offer new insights into the pathophysiological mechanisms of the disease. Although the results show that LTL and the analyzed oxidative stress biomarkers are not associated with disease progression, they support further research on these markers to improve early detection and management of Fabry nephropathy.
|
