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BACKGROUND AND AIMS Fabry disease (FD) is a rare lysosomal storage disease causing progressive kidney, nervous system and heart disorders. Specific therapy may stop or mitigate disease progression, but is very expensive and results depend significantly on early initiation of treatment. Thus, clear criteria for treatment options are necessary. Kidney biopsy in FD has important diagnostic, prognostic and therapeutically implications. Some countries already decided to include as a criterion for reimbursement of FD-specific therapy in presence of renal biopsy evidence related to FD. National criteria for starting FD specific therapy according to renal involvement include eGFR 300 mg/day. METHOD The aim of our retrospective study is to evaluate clinical and histological aspects of renal involvement in untreated female patients diagnosed with FD by genetic test between 2015 and 2021 in our center. Biological renal manifestations using serum creatinine, albumin creatinine ratio and proteinuria. Also, presence of neurological involvement was assessed by clinical exam, electroneurographic exam and brain magnetic resonance, and heart manifestations were assessed by echocardiography, electrocardiogram (ECG), ECG Holter and cardiac magnetic resonance. Kidney biopsy specimens were analyzed by light and electron microscopy. Specific renal FD lesions, as well as general lesions of progression, were evaluated according to the International Study Group of Fabry Nephropathy Score Sheet. RESULTS From a total of 25 female patients, we enrolled 11 female patients in which kidney biopsy was performed. The mean age at diagnosis was 47.7 ± 12 years (range 30–65 years), although mean age of symptoms onset was 36.1 years. The mean eGFR was 72.7 ± 19.8 mL/min/1.72 m2 while mean proteinuria was 0.72 ± 1.3 mg/day. Average Mainz score was 16.6 ± 11.5. Heart involvement was found in five patients (45.5%), and neurological manifestations were present in five patients. Co-morbidities were as follows: arterial hypertension in six patients, diabetes mellitus in one patient and obesity in two patients. All kidney biopsies showed lysosomal accumulation in the podocytes, in the parietal cells of the Bowman capsule and in the tubules, while vascular inclusions were found in nine cases. Also, we observed segmental glomerular sclerosis in four cases and global glomerular sclerosis in three cases, interstitial fibrosis in six cases, tubular atrophy in five cases, arteriosclerosis in four cases and arteriolar hyalinosis in five cases. Considering national criteria for initiation of FD therapy, five patients (54.6%) fulfilled the renal criteria, three patients (27.3%) presented criteria for other organs involvement, while three patients (mean age 37.7 years) did not fulfill any criteria. We emphasize that, even in our six patients without renal criteria for FD therapy, kidney biopsy showed FD-specific lesions (lysosomal accumulation) in all cases, associated with segmental glomerular sclerosis in one case, interstitial fibrosis in four cases, tubular atrophy in three cases, arteriosclerosis in one case and arteriolar hyalinosis in three cases. Thus, in our three patients without clinical, biological and imaging criteria for FD therapy, evidence of specific FD lesions in kidney biopsy supported our recommendation to initiate FD treatment. CONCLUSION The data from our small cohort of females with Fabry disease underline the importance of kidney biopsy for detection of early kidney involvement and provide additional support to the consideration of early initiation of FD-specific therapy, potentially improving long-term outcome. Thus, proof of specific FD renal lesions as revealed by kidney biopsy could become a distinct criterion for initiation of FD therapy, in the absence of other criteria according to current guidelines. Future studies are necessary in order to specify the role of renal histology in the establishment of the proper timing to start the FD treatment, especially in young patients.

Chronic kidney disease (CKD) is an irreversible loss of kidney function, and it represents a major global public health burden due to both its prevalence and its continuously increasing incidence. Mineral bone disorders (MBDs) constitute a hallmark of CKD, and alongside cardiovascular complications, they underlie a poor prognosis for these patients. Thus, our study focused on novel CKD biomarker patterns and their impact on the clinical staging of the disease. As a first testing approach, the relative expression levels of 105 proteins were assessed by the Proteome Profiler Cytokine Array Kit for pooled CKD stage 2–4 serum samples to establish an overall view regarding the proteins involved in CKD pathogenesis. Among the molecules that displayed significant dysregulation in the CKD stages, we further explored the involvement of Dickkopf-related protein 1 (Dkk-1), a recognised inhibitor of the Wnt signalling pathway, and its crosstalk with 1,25OH2D3 (calcitriol) as new players in renal bone and vascular disease. The serum levels of these two molecules were quantified by an ELISA (76 samples), and the results reveal decreasing circulating levels of Dkk-1 and calcitriol in advanced CKD stages, with their circulating expression showing a downward trend as the CKD develops. In the next step, we analysed the inflammation and MBD biomarkers’ expression in CKD (by xMAP array). Our results show that the molecules involved in orchestrating the inflammatory response, interleukin-6 (IL-6) and tumour necrosis factor alpha (TNFα), as well as the mineral biomarkers osteoprotegerin (OPG), osteocalcin (OC), osteopontin (OPN), and fibroblast growth factor 23 (FGF-23), correlate with Dkk-1 and calcitriol, raising the possibility of them being potential useful CKD biomarkers. These results reveal the impact of different biomarker patterns in CKD staging and severity, thus opening up novel approaches to be explored in CKD clinical management.

Chronic kidney disease, despite being a “silent epidemic” disease, represents one of the main causes of mortality in general population, along with cardiovascular disease, which is the leading cause of poor prognosis for these patients. The specific objective of our study was to characterize the relationship between the inflammatory status, the bone disorders markers, and kidney failure in chronic kidney disease patient stages 2–4, in order to design a novel biomarker panel that improves early disease diagnosis and therapeutic response, thus being further integrated into clinical applications. A panel of proteomic biomarkers, assessed by xMAP array, which includes mediators of inflammation (IL-6, TNF-α) and mineral and bone disorder biomarkers (OPG, OPN, OCN, FGF-23, and Fetuin-A), was found to be more relevant than a single biomarker to detect early CKD stages. The association between inflammatory cytokines and bone disorders markers, IL-6, TNF-α, OPN, OPG, and FGF-23, reflects the severity of vascular changes in CKD and predicts disease progression. Proteomic xMAP analyses shed light on a new approach to clinical evaluation for CKD staging and prognosis.