Evaluation of Beta 2-Microglobulin, Cystatin C, and Lipocalin-2 as Renal Biomarkers for Patients with Fabry Disease.

BACKGROUND: Since renal failure is one of the main causes of death in patients with Fabry disease (FD), renal follow-up is an important part of clinical monitoring in these patients. Despite its known limitations, serum creatinine is still the most widely used biomarker. While new renal biomarkers are described, their effectiveness has not yet been fully evaluated in relation to FD. OBJECTIVES: This study aimed to compare renal biomarkers commonly and rarely used in the evaluation of FD patients. METHOD: The usual biomarkers for renal monitoring (microalbuminuria, proteinuria, and creatinine) and some more rarely used (cystatin C, beta 2-microglobulin [ß2M], neutrophil gelatinase-associated lipocalin/lipocalin-2) were quantified in the blood and/or urine samples of 40 FD patients, 39 controls without chronic kidney disease (CKD) paired by age and sex and 38 controls with CKD undergoing hemodialysis. RESULTS: Significant statistical differences (p < 0.05) were observed for cystatin C and lipocalin-2 in plasma levels, for ß2M and serum creatinine levels and by estimated glomerular filtration rate when compared FD patients and control group with CKD and for proteinuria and microalbuminuria in urine samples and for lipocalin-2 in plasma levels when compared FD patients and control group without CKD. Urine creatinine (UCreat), pH, and urine specific gravity did not present a significant statistical difference between groups. CONCLUSION: Considering serum creatinine as gold standard, all renal parameters evaluated, including receiver operating characteristic curve, indicated ß2M as the best biomarker, followed by cystatin C, proteinuria and microalbuminuria, while the results for lipocalin-2 and UCreat do not indicate good predictors of renal impairment. It suggests that at least 2 altered biomarkers should be considered to characterize a renal alteration, thereby establishing a better therapeutic course for FD patients. If possible, along with serum creatinine, measurement of ß2M or cystatin C for renal evaluation of Fabry's patients should be considered.

Rhythmic changes in Fabry disease: Inversion and non-oscillatory pattern in 6-sulfatoxymelatonin daily profile.

Fabry disease is a progressive disease characterized by an enzymatic deficiency of acid alpha-galactosidase and glycosphingolipids storage within the lysosomes. The disease has two phenotypes: classic and nonclassic. Excessive daytime sleepiness is a common sign reported by patients and can be caused by a circadian rhythm sleep disorder. Activity and rest cycle, variation of body temperature and melatonin biosynthesis are known rhythmicity markers. In the face of these evidences, our goal was to evaluate the rhythmic profile in Fabry's disease patients using rhythmicity markers. For this purpose, we recruited 17 patients diagnosed with Fabry disease (11 classic and 6 nonclassic variant) that answered the Epworth Sleepiness Scale and the Morningness-Eveningness questionnaire adapted from Horne and Ostberg; recorded activity and body temperature rhythms by an actigraphy during at least 10 days and collected urine to assess 6-sulfatoxymelatonin excretion load during the day (from the second urine in the morning until 7 p.m.) and night (starting from 7 p.m. until the first urine in the morning of the following day). We observed that control subjects presented higher excretion load of 6-sulfatoxymelatonin during the night (p < 0.05, d = 7.8), as expected. Patients with the nonclassic variant presented an inversion on 6-sulfatoxymelatonin daily profile (p < 0.05, d = 3.8) and there was no difference between the day and night profile of classic variant patients when compared to the other two groups. Patients with the classic variant also presented temperature period greater than 24 hours (p < 0.05, d = 2.0). Therefore, we came to the conclusion that there is an alteration in the circadian rhythms in Fabry disease patients, evidenced by modifications in the 6-sulfatoxymelatonin daily profile and in the body temperature rhythm period.

CD77 levels over enzyme replacement treatment in Fabry Disease Family (V269M) / Níveis de CD77 ao longo do tratamento de reposição enzimática em família com Doença de Fabry (V269M)

ABSTRACT Introduction: Fabry disease (FD) is a disorder caused by mutations in the gene encoding for lysosomal enzyme α-galactosidase A (α-GAL). Reduced α-GAL activity leads to progressive accumulation of globotriaosylceramide (Gb3), also known as CD77. The recent report of increased expression of CD77 in blood cells of patients with FD indicated that this molecule can be used as a potential marker for monitoring enzyme replacement therapy (ERT). Objective: The purpose of this study was to evaluate the CD77 levels throughout ERT in FD patients (V269M mutation). Methods: We evaluated the fluctuations in PBMC (peripheral blood mononuclear cell) membrane CD77 expression in FD patients undergoing ERT and correlated these levels with those observed in different cell types. Results: A greater CD77 expression was found in phagocytes of patients compared to controls at baseline. Interestingly, the variability in CD77 levels is larger in patients at baseline (340 - 1619 MIF) and after 12 months of ERT (240 - 530 MIF) compared with the control group (131 - 331 MFI). Furthermore, by analyzing the levels of CD77 in phagocytes from patients throughout ERT, we found a constant decrease in CD77 levels. Conclusion: The increased CD77 levels in the phagocytes of Fabry carriers together with the decrease in CD77 levels throughout ERT suggest that measuring CD77 levels in phagocytes is a promising tool for monitoring the response to ERT in FD.

RESUMO Introdução: A doença de Fabry (DF) é um distúrbio causado por mutações no gene que codifica a enzima lisossômica α-galactosidase A (α-GAL). A redução da atividade de α-GAL leva ao acúmulo progressivo de globotriaosilceramida (Gb3), também conhecida como CD77. O recente relato de aumento da expressão de CD77 em células sanguíneas de pacientes com DF indicou que essa molécula pode ser utilizada como um potencial marcador para o monitoramento da terapia de reposição enzimática (TRE). Objetivo: O objetivo deste estudo foi avaliar os níveis de CD77 ao longo da TRE em pacientes com DF (mutação V269M). Métodos: Foram avaliadas as flutuações na expressão de CD77 nas membranas das CMSP (células mononucleares do sangue periférico) em pacientes com DF submetidos à TRE e correlacionados com aqueles observados em diferentes tipos de células. Resultados: Uma maior expressão de CD77 foi encontrada em fagócitos de pacientes em comparação aos controles no início do estudo. Curiosamente, a variabilidade nos níveis de CD77 é maior em pacientes no início do estudo (340 - 1619 MIF) e após 12 meses de TRE (240 - 530 MIF) em comparação com o grupo controle (131 - 331 MFI). Além disso, analisando os níveis de CD77 em fagócitos de pacientes ao longo da TRE, encontramos uma diminuição constante nos níveis de CD77. Conclusão: O aumento nos níveis de CD77 nos fagócitos de portadores de Fabry, juntamente com a diminuição nos níveis de CD77 ao longo da TRE, sugerem que medir os níveis de CD77 nos fagócitos é uma ferramenta promissora para monitorar a resposta à TRE na DF.

Clinical parameters, LysoGb3, podocyturia, and kidney biopsy in children with Fabry disease: is a correlation possible?

BACKGROUND: Fabry disease is an X-linked lysosomal storage disorder caused by α-galactosidase enzyme deficiency. We present clinical, biochemical, and histologic findings in children with classical phenotypic presentation of Fabry disease. METHODS: A retrospective analysis was performed using charts from 14 children with confirmed diagnosis. Clinical parameters were evaluated. Globotriaosylsphingosine -lysoGb3- detection in plasma, podocyturia, and kidney biopsy were carried out in all cases. RESULTS: All patients except one demonstrated at least one symptom of Fabry disease. LysoGb3 levels were above the normal range in all patients. Podocyturia was documented in all patients. Kidney biopsy revealed glomerular, interstitial, vascular, and tubular changes on light microscopy in nearly all patients. Electron microscopy showed podocyte inclusions in all patients. CONCLUSIONS: No difference in symptomatology was discernible between boys and girls. Podocyturia was detectable in children serving as a possible early marker of kidney injury. LysoGb3 was elevated in all cases, emphasizing the importance for diagnosis especially in female patients with normal αGal A activity. A possible association between lysoGb3 and symptom severity and histological involvement in kidney biopsy should be assessed in prospective studies with enough statistical power to determine if lysoGb3 can be used to predict nephropathy in children with Fabry disease.

CD77 levels over enzyme replacement treatment in Fabry Disease Family (V269M).

INTRODUCTION: Fabry disease (FD) is a disorder caused by mutations in the gene encoding for lysosomal enzyme α-galactosidase A (α-GAL). Reduced α-GAL activity leads to progressive accumulation of globotriaosylceramide (Gb3), also known as CD77. The recent report of increased expression of CD77 in blood cells of patients with FD indicated that this molecule can be used as a potential marker for monitoring enzyme replacement therapy (ERT). OBJECTIVE: The purpose of this study was to evaluate the CD77 levels throughout ERT in FD patients (V269M mutation). METHODS: We evaluated the fluctuations in PBMC (peripheral blood mononuclear cell) membrane CD77 expression in FD patients undergoing ERT and correlated these levels with those observed in different cell types. RESULTS: A greater CD77 expression was found in phagocytes of patients compared to controls at baseline. Interestingly, the variability in CD77 levels is larger in patients at baseline (340 - 1619 MIF) and after 12 months of ERT (240 - 530 MIF) compared with the control group (131 - 331 MFI). Furthermore, by analyzing the levels of CD77 in phagocytes from patients throughout ERT, we found a constant decrease in CD77 levels. CONCLUSION: The increased CD77 levels in the phagocytes of Fabry carriers together with the decrease in CD77 levels throughout ERT suggest that measuring CD77 levels in phagocytes is a promising tool for monitoring the response to ERT in FD.

Comparing the alpha-galactosidase A biochemical properties from healthy individuals and Fabry disease patients.

BACKGROUND: Due to the importance and the difficulty still present in determining the biochemical diagnosis of Fabry disease (FD), the aim of this study was to establish and compare the biochemical and kinetic properties of alpha-galactosidase A (GLA) in dried blood spots (DBS), plasma and leukocyte samples of FD patients and healthy subjects to evaluate the possible use of these parameters as an auxiliary tool in the diagnosis of this disease. METHODS: GLA activity in DBS, plasma and leukocyte samples from Fabry disease patients and healthy subjects was compared and characterized in terms of optimal pH, Km and Vmax and heat stability. RESULTS: A difference was observed between the Km and Vmax of FD patients and healthy controls using DBS, plasma and leukocyte samples. In leukocytes, pre-incubation at 50°C for 60 min was effective to differentiate FD patients from healthy controls. CONCLUSION: These results can be used as an auxiliary method to the FD diagnosis, especially in cases of patients whose GLA activity is within normal range.

Identification of infants at risk for developing Fabry, Pompe, or mucopolysaccharidosis-I from newborn blood spots by tandem mass spectrometry.

OBJECTIVE: To assess the performance of a tandem mass spectrometry (MS/MS) technology in a newborn screening laboratory to simultaneously measure α-galactosidase, acid-α-glucosidase, and α-L-iduronidase for the detection of infants at risk to develop Fabry, Pompe, or mucopolysaccharidosis (MPS)-I diseases. STUDY DESIGN: Enzyme activity was assayed from a 3.2-mm punch from 100,000+ anonymous newborn blood spots. Punches with low enzyme activity were further evaluated by nucleotide sequence analysis of the responsible gene. Confirmation of affected infants was dependent on identification of mutations compatible with diminished enzyme activity. RESULTS: The technology for simultaneously measuring multiple enzyme activities by MS/MS was successful. The confirmation of diagnosis for Fabry, Pompe, or MPS-I, by DNA sequencing estimated the prevalence of Fabry disease at 1/7800 males (95% CI 1/17,800-1/3600); Pompe disease at 1/27,800 newborns (95% CI 1/90,000-1/10,200); and MPS-I at 1/35,500 newborns (95% CI 1/143,000-1/11,100). These estimates of prevalence are 2 to 4 times greater than the prevalence estimated by clinical diagnosis. The combined prevalence for the 3 disorders was 1/7500 newborns (95% CI 1/13,500-1/4500). CONCLUSIONS: MS/MS for the simultaneous assay of multiple lysosomal enzymes can be successfully introduced into a routine newborn screening laboratory. The technology has a positive predictive value equal to, or better, than methods currently used for the detection of nonlysosomal disorders. Using newborn blood spots, the combined prevalence of Fabry, Pompe, and MPS-I is estimated at 1/7500 newborns based on low-enzyme activity and confirmation by mutation analysis.

Fabry disease peripheral blood immune cells release inflammatory cytokines: role of globotriaosylceramide.

Fabry disease is an X-linked lysosomal disorder (LD) due to deficiency of the enzyme α-galactosidase A (αGal), which leads to the accumulation of neutral glycosphingolipids, mainly globotriaosylceramide (Gb3). Several mechanisms contribute to the diverse physiopathological alterations observed in this disease, and it has been suggested that an underlying proinflammatory state could play a significant role. The aim of this study is to investigate the presence of a proinflammatory state in the different subsets of peripheral blood mononuclear cells (PBMC) and to understand the mechanisms that contribute to its onset and perpetuation. We have shown that cultured PBMC from Fabry patients present a higher proinflammatory cytokine expression and production. Moreover, we determined that among PBMC, dendritic cells and monocytes present a basal proinflammatory cytokine production profile, which is further exacerbated with an inflammatory stimulus. Finally we established that normal, monocyte-derived dendritic cells and macrophages display the same proinflammatory profile when cultured in the presence of Gb3 and an inhibitor of αGal. Furthermore, this effect can be abolished using a TLR4 blocking antibody, indicating that TLR4 is necessary in the process. In summary, our results demonstrate the presence of a proinflammatory state involving two key subsets of innate immunity, and provide direct evidence of Gb3 having a proinflammatory role, likely mediated by TLR4, a finding that could help in the understanding of the underlying causes of the inflammatory pathogenesis of Fabry disease.

Comparison between alpha-galactosidase A activity in blood samples collected on filter paper, leukocytes and plasma.

OBJECTIVES: To compare alpha-galactosidase A activity in dried blood spots on filter paper, plasma, and leukocytes of Fabry disease patients and healthy controls, and to develop a miniaturization approach of the techniques to measure activity using plasma and leukocytes. DESIGN AND METHODS: Blood was collected from healthy controls and Fabry disease patients. Two drops were spotted on filter paper. Plasma and leukocytes were separated from the remaining sample. Enzyme activity was assessed by fluorometry. RESULTS: Significant positive correlation between standard and miniaturized techniques was observed. Alpha-galactosidase activity differed for male and female subjects when analyzed using filter paper and plasma. New reference and cutoff values were established based on the differences in alpha-galactosidase activity between genders. A good correlation was observed across biological materials assessed. CONCLUSIONS: The establishment of specific values for men and women increases reliability of commonly used techniques to screen and diagnose Fabry disease.

Leukocyte perturbation associated with Fabry disease.

Fabry disease is an X-linked lysosomal storage disorder of glycosphingolipid catabolism due to the deficient activity of the enzyme alpha-galactosidase A. The non-degraded substrate, mainly globotriaosylceramide (Galα1-4Galß1-4Glcß1-1Cer; Gb(3)) accumulates progressively in the lysosome of various cells. The aim of this work was to analyse changes in leukocyte subpopulations and surface markers and to determine whether Gb(3) is increased in leukocytes of patients with untreated and treated Fabry disease. Blood samples obtained from 22 male Fabry patients (11 untreated and 11 on enzyme replacement therapy) and 22 normal controls were subjected to flow cytometric analysis of Gb(3) intracellular content, leukocyte subpopulations and cell markers. Based on the fluorescence intensity of bound monoclonal antibody, and relative to normal control leukocytes, Gb(3) appeared significantly increased in lymphocytes (but not in monocytes or granulocytes) from patients with Fabry disease. A significantly higher percentage of lymphocytes and CD19(+) cells and a reduced proportion of monocytes, CD8(+) cells and myeloid dendritic cells were detected in samples from Fabry patients compared with normal controls. CD1d expression was significantly lower and MHC class II surface expression was significantly higher in monocytes from Fabry patients than in normal controls. As previously observed for other adhesion molecules, the expression of CD31 (PECAM) was higher in leukocytes from Fabry patients. In conclusion, the differences recorded in this study reveal a leukocyte perturbation associated with the disease state in Fabry patients, whereas some abnormalities are less marked in treated patients.

Safety and efficacy of enzyme replacement therapy with agalsidase beta: an international, open-label study in pediatric patients with Fabry disease.

OBJECTIVE: To evaluate the safety and explore the efficacy of enzyme replacement therapy with agalsidase beta (recombinant human alpha-galactosidase A; Fabrazyme [Genzyme Corporation, Cambridge, MA]) in pediatric patients with Fabry disease, a genetic disorder in which deficient endogenous enzyme causes pathogenic tissue accumulation of globotriaosylceramide (GL-3). STUDY DESIGN: Fourteen male and 2 female patients, 8 to 16 years old, were treated in this open-label study. A 12-week observation period to collect baseline data preceded the 48-week treatment period when agalsidase beta (1 mg/kg) was infused intravenously every 2 weeks. No primary efficacy end point was specified. RESULTS: Before treatment, results of skin biopsies from 12 male patients showed moderate or severe GL-3 accumulation in superficial dermal capillary endothelial cells; with treatment, these cells were completely cleared of GL-3 in week-24 biopsies from all 12 male patients and in all available week-48 biopsies. With treatment, reports of gastrointestinal symptoms declined steadily. Patient diaries documented significant reductions in school absences due to sickness. Agalsidase beta was generally well tolerated; most treatment-related adverse events were mild or moderate infusion-associated reactions involving rigors, fever, or rhinitis. CONCLUSIONS: Agalsidase beta safely and effectively reduced the GL-3 accumulation in dermal endothelium already evident in children with Fabry disease. Early intervention may prevent irreversible end-organ damage from chronic GL-3 deposition.

High incidence of autoantibodies in Fabry disease patients.

Fabry disease (FD) is an X-linked disorder of glycosphingolipid catabolism that results from a deficiency of the lysosomal enzyme alpha-galactosidase A. This defect leads to the accumulation of its substrates, mainly globotriaosylceramide, in lysosomes of cells of different tissues. Different studies have shown the involvement of immunopathologies in different sphingolipidoses. The coexistence of FD and immune disorders such as systemic lupus erythematosus, rheumatoid arthritis and IgA nephropathy, has been described in the literature. The aim of this study was to evaluate the prevalence of a group of autoantibodies in a series of Argentine FD patients. Autoantibodies against extractable nuclear antigens (ENAs), double-stranded DNA, anticardiolipin and phosphatidylserine were assayed by ELISA. Lupus anticoagulants were also tested. Fifty-seven per cent of the samples showed reactivity with at least one autoantigen. Such reactivities were more frequent among males than among females. Antiphospholipid autoantibodies were detected in 45% of our patients. The high rate of thrombosis associated with FD could be related, at least in part, to the presence of antiphospholipid autoantibodies in Fabry patients. We found the presence of ENAs, which are a characteristic finding of rheumatological diseases, previous a frequent misdiagnosis of FD, in around 39% of the cases. The detection of a high level of autoantibodies must be correlated clinically to determine the existence of an underlying autoimmune disease. With the recent development of therapy, the life expectancy in FD will increase and autoimmune diseases might play an important role in the morbidity of FD.