Interfering parameters in the determination of urinary globotriaosylceramide (Gb3) in patients with chronic kidney disease

The MicroRNA Prediction Models as Ancillary Diagnosis Biomarkers for Urothelial Carcinoma in Patients With Chronic Kidney Disease

Urothelial carcinoma is a common urological cancer in chronic kidney disease patients. Cystoscopy and urine cytology are the clinical diagnostic tools for UC. However, cystoscopy is an invasive procedure, while urine cytology showed low sensitivity for low-grade urothelial tumors. High accuracy with non-invasive tools for UC is needed for CKD patients. Our study collected a total of 272 urine and 138 plasma samples to detect the miRNA expression levels for establishing UC signatures from CKD patients. Seventeen candidate miRNAs of biofluids were selected and confirmed by qRT-PCR. Our results showed that urinary miR-1274a and miR-30a-5p expression levels were significantly lower but miR-19a-5p expression levels were higher in UC when compared with CKD. In plasma samples, miR-155-5p, miR-19b-1-5p, miR-378, and miR-636 showed significantly lower expression in UC compared to those with CKD. The Kaplan-Meier curve showed that lower expression of miR-19a, miR-19b, miR-636 and miR-378, and higher expression of miR-708-5p were associated with poor prognosis in patients with bladder cancer. In addition, we produced classifiers for predicting UC by multiple logistic regression. The urine signature was developed with four miRNAs, and the AUC was 0.8211. Eight miRNA expression levels from both urine and plasma samples were examined, and the AUC was 0.8595. Two miRNA classifiers and the nomograms could improve the drawbacks of current UC biomarker screenings for patients with CKD.

Comparative urinary globotriaosylceramide analysis by thin-layer chromatography-immunostaining and liquid chromatography-tandem mass spectrometry in patients with Fabry disease

In Fabry disease, accumulation of glycolipids, predominantly globotriaosylceramide (Gb3), affects the kidneys, and nephropathy is one of the important disorders that influence the disease severity and prognosis of patients. Urinary Gb3 has been analyzed for diagnosis and monitoring of Fabry disease. In this study, we analyzed urinary Gb3 by thin-layer chromatography (TLC)-immunostaining and liquid chromatography (LC)-tandem mass spectrometry (MS/MS). An improved qualitative method, TLC-immunostaining, revealed excessive urinary Gb3 excretion in 100 (8/8), 88 (14/16), and 74% (45/61) of the classic Fabry males, later-onset Fabry males, and Fabry females examined, respectively. This authentic method is robust, easy, economic, and hardly affected by abundant urinary sediment, and this is useful for diagnosing individual Fabry patients. LC-MS/MS can determine the level of Gb3 in urine with high sensitivity, and it revealed that the Gb3 excretion level was higher in the order of classic Fabry males, later-onset Fabry males, Fabry females, and controls, respectively, and this is expected to be a useful quantitative method not only for diagnosis but also for predicting the progression of Fabry nephropathy. As to the relation of the urinary Gb3 level and renal events, our study revealed that the urinary Gb3 level in Fabry patients experiencing renal events tended to be higher than that in ones who did not have any renal events in each phenotypic group of the disease.

An antibody binding-based fluorescent assay for the rapid quantification of globotriaosylceramide levels in human Fabry cells

Fabry disease is caused by reduced α-GAL A activity and accumulation of globotriaosylceramide (Gb₃). Here, we describe a microplate Gb₃ assay using fluorophore-tagged antibody and crude cellular lipid extracts. The assay is able to detect higher Gb₃ concentrations in human Fabry cells compared to non-diseased cells. This result was verified by immunofluorescence staining that revealed large amounts of Gb₃ deposits in Fabry cell lines, demonstrating the accuracy of this method. This assay may provide the basis for detecting Fabry disease by quantifying Gb₃ deposits from human biological samples, for example, from urine and blood.

Fabry Nephropathy: An Evidence-Based Narrative Review

Fabry disease (FD) is a rare, X-linked disorder caused by mutations in the GLA gene encoding the enzyme α-galactosidase A. Complete or partial deficiency in this enzyme leads to intracellular accumulation of globotriaosylceramide (Gb3) and other glycosphingolipids in many cell types throughout the body, including the kidney. Progressive accumulation of Gb3 in podocytes, endothelial cells, epithelial cells, and tubular cells contribute to the renal symptoms of FD, which manifest as proteinuria and reduced glomerular filtration rate leading to renal insufficiency. A correct diagnosis of FD, although challenging, has considerable implications regarding treatment, management, and counseling. The diagnosis may be confirmed by demonstrating the enzyme deficiency in males and by identifying the specific GLA gene mutation in male and female patients. Treatment with enzyme replacement therapy, as part of the therapeutic strategy to prevent complications of the disease, may be beneficial in stabilizing renal function or slowing its decline, particularly in the early stages of the disease. Emergent treatments for FD include the recently approved chaperone molecule migalastat for patients with amenable mutations. The objective of this report is to provide an updated overview on Fabry nephropathy, with a focus on the most relevant aspects of its epidemiology, diagnosis, pathophysiology, and treatment options.

Tandem Mass Spectrometry of Sphingolipids: Applications for Diagnosis of Sphingolipidoses

In recent years, mass spectrometry (MS) has become the dominant technology in lipidomic analysis. It is widely used in diagnosis and research of lipid metabolism disorders including those characterized by impairment of lysosomal functions and storage of nondegraded-degraded substrates. These rare diseases, which include sphingolipidoses, have severe and often fatal clinical consequences. Modern MS methods have contributed significantly to achieve a definitive diagnosis, which is essential in clinical practice to begin properly targeted patient care. Here we summarize MS and tandem MS methods used for qualitative and quantitative analysis of sphingolipids (SL) relative to the diagnostic process for sphingolipidoses and studies focusing on alterations in cell functions due to these disorders. This review covers the following topics: Tandem MS is sensitive and robust in determining the composition of sphingolipid classes in various biological materials. Its ability to establish SL metabolomic profiles using MS bench-top analyzers, significantly benefits the first stages of a diagnosis as well as metabolic studies of these disorders. It can thus contribute to a better understanding of the biological significance of SL.

Podocyturia is significantly elevated in untreated vs treated Fabry adult patients

BACKGROUND

Proteinuria suggests kidney involvement in Fabry disease. We assessed podocyturia, an early biomarker, in controls and patients with and without enzyme therapy, correlating podocyturia with proteinuria and renal function.

METHODS

Cross-sectional study (n = 67): controls (Group 1, n = 30) vs. Fabry disease (Group 2, n = 37) subdivided into untreated (2A, n = 19) and treated (2B, n = 18). Variables evaluated: age, gender, creatinine, CKD-EPI, proteinuria, podocyte count/10 20× microscopy power fields, podocytes/100 ml urine, podocytes/g creatininuria (results expressed as median and range).

RESULTS

Group 1 vs. 2 did not differ concerning age, gender and CKD-EPI, but differed regarding proteinuria and podocyturia. Group 2A vs. 2B: age: 29 (18-74) vs. 43 (18-65) years (p = ns); gender: males n = 3 (16 %) vs. n = 9 (50 %). Proteinuria was significantly higher in Fabry treated patients, while CKD-EPI and podocyturia were significantly elevated in untreated individuals. Significant correlations: group 2A: age-proteinuria, ρ = 0.62 (p = 0.0044); age-CKD-EPI, ρ = -0.84 (p < 0.0001); podocyturia-podocytes/100 ml urine, ρ = 0.99 (p = 0.0001); podocyturia-podocytes/g creatininuria ρ = 0.86 (p = 0.0003), podocytes/100 ml urine-podocytes/g urinary creatinine, ρ = 0.84 (p = 0.0004); proteinuria-CKD-EPI, ρ = -0.68 (p = 0.0013). Group 2B: podocyturia-podocytes/100 ml urine, ρ = 0.88 (p < 0.0001); podocyturia-podocytes/g creatininuria, ρ = 0.84 (p < 0.0001); podocytes/100 ml urine-podocytes/g creatininuria, ρ = 0.94 (p < 0.0001); CKD-EPI-proteinuria, ρ = -0.66 (p = 0.0028).

CONCLUSIONS

Patients with Fabry disease display heavy podocyturia; those untreated present significantly higher podocyturia, lower proteinuria and better renal function than those who are treated, suggesting that therapy may be started at advanced stages. Podocyturia may antedate proteinuria, and enzyme therapy may protect against podocyte loss.

Screening for Fabry Disease by Urinary Globotriaosylceramide Isoforms Measurement in Patients with Left Ventricular Hypertrophy

BACKGROUND

Left ventricular hypertrophy (LVH) is a frequent echocardiographic feature in Fabry disease (FD) and in severe cases may be confused with hypertrophic cardiomyopathy (HCM) of other origin. The prevalence of FD in patients primarily diagnosed with HCM varies considerably in screening and case finding studies, respectively. In a significant proportion of patients, presenting with only mild or moderate LVH and unspecific clinical signs FD may remain undiagnosed. Urinary Gb3 isoforms have been shown to detect FD in both, women and men. We examined whether this non-invasive method would help to identify new FD cases in a non-selected cohort of patients with various degree of LVH.

METHODS AND RESULTS

Consecutive patients older than 18 years with a diastolic interventricular septal wall thickness of ≥12mm determined by echocardiography were included. Referral diagnosis was documented and spot urine was collected. Gb3 was measured by mass spectroscopy. Subjects with an elevated Gb3-24:18 ratio were clinically examined for signs of FD, α-galactosidase-A activity in leukocytes was determined and GLA-mutation-analysis was performed. We examined 2596 patients. In 99 subjects urinary Gb3 isoforms excretion were elevated. In these patients no new cases of FD were identified by extended FD assessment. In two of three patients formerly diagnosed with FD Gb3-24:18 ratio was elevated and would have led to further diagnostic evaluation.

CONCLUSION

Measurement of urinary Gb3 isoforms in a non-selected cohort with LVH was unable to identify new cases of FD. False positive results may be prevented by more restricted inclusion criteria and may improve diagnostic accuracy of this method.