Sandro Feriozzi

Discovery of new risk loci for IgA nephropathy implicates genes involved in immunity against intestinal pathogens

We performed a genome-wide association study (GWAS) of IgA nephropathy (IgAN), the most common form of glomerulonephritis, with discovery and follow-up in 20,612 individuals of European and East Asian ancestry. We identified six new genome-wide significant associations, four in ITGAM-ITGAX, VAV3 and CARD9 and two new independent signals at HLA-DQB1 and DEFA. We replicated the nine previously reported signals, including known SNPs in the HLA-DQB1 and DEFA loci. The cumulative burden of risk alleles is strongly associated with age at disease onset. Most loci are either directly associated with risk of inflammatory bowel disease (IBD) or maintenance of the intestinal epithelial barrier and response to mucosal pathogens. The geospatial distribution of risk alleles is highly suggestive of multi-locus adaptation, and genetic risk correlates strongly with variation in local pathogens, particularly helminth diversity, suggesting a possible role for host–intestinal pathogen interactions in shaping the genetic landscape of IgAN.

Validation of the Oxford classification of IgA nephropathy in cohorts with different presentations and treatments

The Oxford Classification of IgA Nephropathy (IgAN) identified mesangial hypercellularity (M), endocapillary proliferation (E), segmental glomerulosclerosis (S), and tubular atrophy/interstitial fibrosis (T) as independent predictors of outcome. Whether it applies to individuals excluded from the original study and how therapy influences the predictive value of pathology remain uncertain. The VALIGA study examined 1147 patients from 13 European countries that encompassed the whole spectrum of IgAN. Over a median follow-up of 4.7 years, 86% received renin–angiotensin system blockade and 42% glucocorticoid/immunosuppressive drugs. M, S, and T lesions independently predicted the loss of estimated glomerular filtration rate (eGFR) and a lower renal survival. Their value was also assessed in patients not represented in the Oxford cohort. In individuals with eGFR less than 30 ml/min per 1.73 m2, the M and T lesions independently predicted a poor survival. In those with proteinuria under 0.5 g/day, both M and E lesions were associated with a rise in proteinuria to 1 or 2 g/day or more. The addition of M, S, and T lesions to clinical variables significantly enhanced the ability to predict progression only in those who did not receive immunosuppression (net reclassification index 11.5%). The VALIGA study provides a validation of the Oxford classification in a large European cohort of IgAN patients across the whole spectrum of the disease. The independent predictive value of pathology MEST score is reduced by glucocorticoid/immunosuppressive therapy.

Agalsidase Alfa Slows the Decline in Renal Function in Patients with Fabry Disease

The aim of this study was to determine the effects of enzyme replacement therapy with agalsidase α on renal function in patients with Fabry nephropathy. Serum creatinine data were collected from 165 adult patients during 3 years of treatment. Serum creatinine increased in all men whereas it was stable in women, except in stage II renal disease (Kidney Disease Outcomes Quality Initiative). The estimated glomerular filtration rate (eGFR) declined in males with stage I and II (from 115.0 ± 22.2 to 98.3 ± 27.3 and from 76.5 ± 8.1 to 66.3 ±21.6 ml/min/1.73 m2, respectively; both p < 0.01), whereas eGFR was stable in stage III. In females, eGFR was stable in stages I and III, and decreased in stage II (from 72.5 ± 8.3 to 67.3 ± 13.6 ml/min/1.73 m2; p = 0.01). The 24-hour proteinuria was <1 g in all patients, and most patients (96%) were treated with angiotensin receptor blockers (ARBs) or angiotensin-converting enzyme (ACE) inhibitors. Agalsidase α in combination with ACE inhibitors/ARB may be effective in slowing the deterioration in renal function in Fabry nephropathy.

The Effectiveness of Long-Term Agalsidase Alfa Therapy in the Treatment of Fabry Nephropathy

BACKGROUND AND OBJECTIVES Fabry disease is a rare X-linked disease with multisystemic manifestations. This study investigated the effectiveness of long-term enzyme replacement therapy with agalsidase alfa in Fabry nephropathy treatment. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS In this observational study, data on patients receiving agalsidase alfa (0.2 mg/kg every other week) were extracted from the Fabry Outcome Survey, an international registry of patients with Fabry disease. Serum creatinine and estimated GFR (eGFR) at baseline and after ≥5 years of treatment were assessed; 24-hour urinary protein excretion and BP measurements were also reviewed. The eGFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration formula. Patients with an eGFR <30 ml/min per 1.73 m(2) were excluded. RESULTS Renal function was assessed in 208 patients (mean enzyme replacement therapy, 7.4 years; range, 5.0-11.2 years). Mean yearly change in eGFR was -2.2 ml/min per 1.73 m(2) in men and -0.7 ml/min per 1.73 m(2) in women (95% confidence limits, -2.8; -1.7 and -1.4; 0.0, respectively). Patients with 24-hour protein excretion >1 g/24 h had poorer renal function at baseline and follow-up compared with patients with protein excretion of 500-1000 mg/24 h or with proteinuria <500 mg/24 h. Renal function was worse in patients with baseline arterial hypertension, and there was a more rapid yearly decline compared with normotensive patients. CONCLUSIONS This study suggests that long-term agalsidase alfa therapy is able to stabilize the rate of Fabry nephropathy progression in women and is associated with a mild to moderate decline of renal function in men.

Fabry nephropathy: a review – how can we optimize the management of Fabry nephropathy?

Fabry disease is a rare, X-linked, lysosomal storage disease caused by mutations in the gene encoding the enzyme alpha-galactosidase A. Complete or partial deficiency in this enzyme leads to intracellular accumulation of globotriaosylceramide (Gb3) and related glycosphingolipids in many cell types throughout the body, including the kidney. Progressive accumulation of Gb3 in podocytes, epithelial cells and the tubular cells of the distal tubule and loop of Henle contribute to the renal symptoms of Fabry disease, which manifest as proteinuria and reduced glomerular filtration rate leading to chronic kidney disease and progression to end-stage renal disease. Early diagnosis and timely initiation of treatment of Fabry renal disease is an important facet of disease management. Initiating treatment with enzyme replacement therapy (ERT; agalsidase alfa, Replagal®, Shire; agalsidase beta, Fabrazyme®, Genzyme) as part of a comprehensive strategy to prevent complications of the disease, may be beneficial in stabilizing renal function or slowing its decline. Early initiation of ERT may also be more effective than initiating therapy in patients with more advanced disease. Several strategies are required to complement the use of ERT and treat the myriad of associated symptoms and organ involvements. In particular, patients with renal Fabry disease are at risk of cardiovascular events, such as high blood pressure, cardiac arrhythmias and stroke. This review discusses the management of renal involvement in Fabry disease, including diagnosis, treatments, and follow-up, and explores recent advances in the use of biomarkers to assist with diagnosis, monitoring disease progression and response to treatment.

Kidney transplantation in patients with Fabry disease

Little is known about the effects of enzyme replacement therapy (ERT) in kidney transplant recipients with Fabry disease. Clinical characteristics of transplant recipients in the Fabry Outcome Survey (FOS) were therefore examined in patients with Fabry disease with or without ERT. Of the 837 European patients in FOS (March 2006), 34 male patients and two female patients had received kidney transplants. Mean age at transplantation was 37.6 ± 10.9 years, mean time since transplantation was 7.7 ± 6.4 years, median estimated glomerular filtration rate (eGFR) was 44.4 ml/min/1.73 m2, and median proteinuria was 296 mg/24 h. Of 27 patients with baseline data, 59% had hypertension, 74% had left ventricular hypertrophy, 22% had cardiac valve disease, 30% had arrhythmia, and 22% had transient ischaemic attacks and 15% stroke. Twenty patients (74%; two female patients, 18 male patients) were receiving ERT with agalsidase alfa. At enrolment or at the start of ERT, median eGFRs were 59 and 35 ml/min/1.73 m2 (P = 0.05) and median proteinuria levels were 240 and 420 mg/24 h (not significant) in treated and untreated patients respectively. Renal function remained stable in patients receiving ERT. In conclusion, agalsidase alfa is well tolerated in patients with Fabry disease who have undergone renal transplantation.

Screening, diagnosis, and management of patients with Fabry disease: conclusions from a “Kidney Disease: Improving Global Outcomes” (KDIGO) Controversies Conference

Patients with Fabry disease (FD) are at a high risk for developing chronic kidney disease and cardiovascular disease. The availability of specific but costly therapy has elevated the profile of this rare condition. This KDIGO conference addressed controversial areas in the diagnosis, screening, and management of FD, and included enzyme replacement therapy and nonspecific standard-of-care therapy for the various manifestations of FD. Despite marked advances in patient care and improved overall outlook, there is a need to better understand the pathogenesis of this glycosphingolipidosis and to determine the appropriate age to initiate therapy in all types of patients. The need to develop more effective specific therapies was also emphasized.

Dialysis and Transplantation in Fabry Disease: Indications for Enzyme Replacement Therapy

ESRD is a major cause of morbidity and premature mortality in Fabry disease, particularly in classically affected males. The decline of renal function in Fabry nephropathy is adversely affected by male gender, advanced chronic kidney disease (CKD), and severe proteinuria. The diagnosis of Fabry nephropathy may be missed if not specifically addressed in progressive CKD and patients have been first identified in screening programs of dialysis patients. Fabry patients have worse 3-year survival rates on dialysis as compared with nondiabetic controls. The 5-year survival rate of transplanted Fabry patients is also lower than that of controls. However, because Fabry nephropathy does not recur in the allograft and transplanted Fabry patients appear to have better overall outcomes than those maintained on dialysis, kidney transplantation should be recommended as a first choice in renal replacement therapy (RRT) for Fabry disease. Appropriately designed and powered studies are not available to answer the question whether enzyme replacement therapy (ERT) influences outcomes, the course of cardiomyopathy, events, or survival in Fabry patients on RRT. The authors are not aware of compelling indications for ERT in RRT patients because progression of cardiomyopathy was documented during ERT. Whether the excess mortality risk of Fabry patients on RRT can be prevented by ERT is unknown. Despite observational reports of symptomatic improvement, the available evidence supporting ERT for such patients is not compelling enough. To clarify this issue, studies are needed to test the effectiveness of agalsidases in preventing cardiac and cerebrovascular complications in Fabry patients with ESRD.

Tonsillectomy in a European Cohort of 1,147 Patients with IgA Nephropathy

Background: Tonsillectomy has been considered a treatment for IgA nephropathy (IgAN). It is aimed at removing a source of pathogens, reducing mucosa-associated lymphoid tissue and decreasing polymeric IgA synthesis. However, its beneficial effect is still controversial. In Asia, favorable outcomes have been claimed mostly in association with corticosteroids. In Europe, small, single-center uncontrolled studies have failed to show benefits. Methods: The European validation study of the Oxford classification of IgAN (VALIGA) collected data from 1,147 patients with IgAN over a follow-up of 4.7 years. We investigated the outcome of progression to end-stage renal disease (ESRD) and/or 50% loss of estimated glomerular filtration rate (eGFR) and the annual loss of eGFR in 61 patients who had had tonsillectomy. Results: Using the propensity score, which is a logistic regression model, we paired 41 patients with tonsillectomy and 41 without tonsillectomy with similar risk of progression (gender, age, race, mean blood pressure, proteinuria, eGFR at renal biopsy, previous treatments and Oxford MEST scores). No significant difference was found in the outcome. Moreover, we performed an additional propensity score pairing 17 patients who underwent tonsillectomy after the diagnosis of IgAN and 51 without tonsillectomy with similar risk of progression at renal biopsy and subsequent treatments. No significant difference was found in changes in proteinuria, or in the renal end point of 50% reduction in GFR and/or ESRD, or in the annual loss of eGFR. Conclusion: In the large VALIGA cohort of European subjects with IgAN, no significant correlation was found between tonsillectomy and renal function decline.

Kidney transplantation and enzyme replacement therapy in patients with Fabry disease.

During Fabry disease, progressive glycosphingolipid deposition in the kidney causes gradual deterioration of renal function with proteinuria, uremia and hypertension. This results in end-stage renal disease (ESRD) which is one of the leading causes of morbidity and premature mortality in affected patients. Given the excellent graft and patient survival generally nowadays, kidney transplantation is the first choice to correct renal dysfunction and improve the overall prognosis of patients with renal failure because of Fabry disease. The benefit of enzyme-replacement therapy (ERT) in kidney transplanted Fabry patients has been controversially discussed and long-term trials focusing on the effectiveness of agalsidase in this patient population are needed.