David Ribes

Pregnancy-Associated Hemolytic Uremic Syndrome Revisited in the Era of Complement Gene Mutations

In contrast to pregnancy-associated thrombotic thrombocytopenic purpura, the pathogenesis and presentation of pregnancy-associated atypical hemolytic uremic syndrome (P-aHUS) remain ill-defined. We conducted a retrospective study to assess the presentation and outcomes of patients presenting with P-aHUS and the prevalence of alternative C3 convertase dysregulation. P-aHUS occurred in 21 of the 100 adult female patients with atypical HUS, with 79% presenting postpartum. We detected complement abnormalities in 18 of the 21 patients. The outcomes were poor: 62% reached ESRD by 1 month and 76% by last follow-up. The risk for P-aHUS was highest during a second pregnancy. Thirty-five women, 26 (74%) of whom had complement abnormalities, had at least one pregnancy before the onset of a non-pregnancy-related aHUS. Outcomes did not differ between patients with pregnancy-related and non-pregnancy-related aHUS. Mutations in the SCR19-20 domains of factor H were less frequent in P-aHUS patients compared with non-pregnancy-related aHUS. Pregnancies in female patients with complement abnormalities (n = 44) were complicated by fetal loss and preeclampsia in 4.8% and 7.7%, respectively. Better understanding of complement dysregulation in pregnancy complications is essential, especially to guide development of pharmacologic agents to modulate this system.

Incidence and Predictive Factors for Infectious Disease after Rituximab Therapy in Kidney-Transplant Patients

Rituximab off‐label use includes organ transplantation. We review the occurrence of infectious disease and its outcome after rituximab therapy. Between April 2004 and August 2008, 77 kidney‐transplant patients received rituximab therapy [2–8 courses (median 4) of 375 mg/m2 each] for various reasons. Their results were compared with a control group (n = 902) who had received no rituximab. After a median follow‐up of 16.5 (1–55) months for rituximab patients and 60.9 (1.25–142.7) months for control patients, the incidence of infectious disease was 45.45% and 53.9% (ns), respectively. The incidence of bacterial infection was similar between the two groups, whereas the viral‐infection rate was significantly lower, and the rate of fungal infection was significantly higher in the rituximab group. Nine out of 77 patients (11.68%) died after rituximab therapy, of which seven deaths (9.09%) were related to an infectious disease, compared to 1.55% in the controls (p = 0.0007). In the whole population, the independent predictive factors for infection‐induced death were the combined use of rituximab and antithymocyte‐globulin given for induction or anti‐rejection therapy, recipient age, and bacterial and fungal infections. After kidney transplantation, the use of rituximab is associated with a high risk of infectious disease and death related to infectious disease.

Hyperfunctional C3 convertase leads to complement deposition on endothelial cells and contributes to atypical hemolytic uremic syndrome

Complement is a major innate immune defense against pathogens, tightly regulated to prevent host tissue damage. Atypical hemolytic uremic syndrome (aHUS) is characterized by endothelial damage leading to renal failure and is highly associated with abnormal alternative pathway regulation. We characterized the functional consequences of 2 aHUS-associated mutations (D(254)G and K(325)N) in factor B, a key participant in the alternative C3 convertase. Mutant proteins formed high-affinity C3-binding site, leading to a hyperfunctional C3 convertase, resistant to decay by factor H. This led to enhanced complement deposition on the surface of alternative pathway activator cells. In contrast to native factor B, the 2 mutants bound to inactivated C3 and induced formation of functional C3-convertase on iC3b-coated surface. We demonstrated for the first time that factor B mutations lead to enhanced C3-fragment deposition on quiescent and adherent human glomerular cells (GEnCs) and human umbilical vein endothelial cells (HUVECs), together with the formation of sC5b-9 complexes. These results could explain the occurrence of the disease, since excessive complement deposition on endothelial cells is a central event in the pathogenesis of aHUS. Therefore, risk factors for aHUS are not only mutations leading to loss of regulation, but also mutations, resulting in hyperactive C3 convertase.

Efficacy and Safety of Sofosbuvir-Based Antiviral Therapy to Treat Hepatitis C Virus Infection After Kidney Transplantation.

There is no approved therapy for hepatitis C virus (HCV) infection after kidney transplantation, and no data regarding the use of new‐generation direct antiviral agents (DAAs) have been published so far. The aims of this pilot study were to assess the efficacy and safety of an interferon‐free sofosbuvir‐based regimen to treat chronic HCV infection in kidney transplant recipients. Twenty‐five kidney transplant recipients with chronic HCV infection were given, for 12 (n = 19) or 24 weeks (n = 6), sofosbuvir plus ribavirin (n = 3); sofosbuvir plus daclatasvir (n = 4); sofosbuvir plus simeprevir, with (n = 1) or without ribavirin (n = 6); sofosbuvir plus ledipasvir, with (n = 1) or without ribavirin (n = 9); and sofosbuvir plus pegylated‐interferon plus ribavirin (n = 1). A rapid virological response, defined by undetectable viremia at week 4 after starting DAA therapy, was observed in 22 of the 25 patients (88%). At the end of therapy, HCV RNA was undetectable in all patients. At 4 and 12 weeks after completing DAA therapy, all had a sustained virological response. The tolerance to anti‐HCV therapy was excellent and no adverse event was observed. A significant decrease in calcineurin inhibitor levels was observed after HCV clearance. New‐generation oral DAAs are efficient and safe to treat HCV infection after kidney transplantation.

Hepatitis E virus and the kidney in solid-organ transplant patients.

Background. Hepatitis E virus (HEV) infection is an emerging disease in industrialized countries. Few data regarding genotype 3 HEV extrahepatic manifestations exist. Methods. We assessed kidney function and histology in solid-organ transplant patients during HEV infection. In all, 51 cases of genotype 3 HEV infections were diagnosed (34 kidney, 14 liver, and 3 kidney-pancreas transplant patients). Of these, 43.2% were cleared of the virus spontaneously within 6 months of infection, whereas 56.8% evolved to chronic hepatitis. Twelve of these patients completed a 3-month antiviral therapy and were followed up for 6 months posttreatment. Kidney function (estimated glomerular filtration rate [eGFR] obtained by the Modification of Diet in Renal Disease equation) and proteinuria were assessed before infection, during HEV infection and during follow-up. Kidney biopsies were obtained from patients with high proteinuria and decreased eGFR levels. Results. During HEV infection, there was a significant decrease in eGFR in both kidney- and liver-transplant patients. Glomerular diseases were observed in kidney biopsies obtained during the acute and chronic phases. This included membranoproliferative glomerulonephritis and relapses in IgA nephropathy. The majority of patients had cryoglobulinemia that became negative after HEV clearance. Kidney function improved and proteinuria decreased after HEV clearance. Conclusion. HEV-associated glomerulonephritis seems to be an HEV-related extrahepatic manifestation. Further studies are required to confirm these observations.

Leflunomide treatment for polyomavirus BK-associated nephropathy after kidney transplantation.

Polyomavirus‐associated nephropathy (PVAN) affects 1–10% of kidney‐transplant (KT) patients, with graft failure/loss in approximately 90% of cases. Reducing immunosuppression is the key treatment option, but addition of leflunomide may improve BK Virus (BKV) clearance and graft survival. In a prospective open‐labeled study, 12 KT patients with biopsy‐proven PVAN were treated with reduced immunosuppression and leflunomide. BKV viremia and graft function were followed. PVAN was diagnosed at 6 months (3–192) post‐transplant; median serum creatinine concentration (sCC) was 189 μmol/l (92–265). After 16 months (8–30) of follow‐up, the sCC was 150 μmol/l (90–378, NS). Renal function improved in six cases (50%), remained stable in two (16.6%) and deteriorated in four (33.4%), with graft loss in two (17%). Clearance of BKV viremia was observed in five (42%) cases. Side effects included anemia in six cases leading to leflunomide withdrawal in two patients, and mild thrombocytopenia. In KT patients diagnosed with PVAN, leflunomide plus reduced immunosuppression improved graft function in 66.6%, cleared BKV viremia in 42%, and resulted in side effects in 17%. This limited efficacy contrasts with other reports and falls short of expectation. We conclude that active screening, earlier diagnosis and intervention remain the cornerstones of treatment.

Long-Term Ribavirin Therapy in Hepatitis C Virus-Positive Renal Transplant Patients: Effects on Renal Function and Liver Histology

BACKGROUND Long-term renal transplant (RT) recipient mortality and graft loss increase significantly in hepatitis C virus positive (HCV-[+]ve) patients. Treatment with alpha-interferon in this population is associated with a high rate of acute rejection. The aims of this study were the evaluation of the efficacy and the safety of ribavirin monotherapy in 16 HCV-(+) RT patients (group A) matched to 32 HCV-(+) RT patients (group B) who did not receive ribavirin. METHODS Ribavirin was started at a daily dose of 1,000 mg and then adapted to hemoglobin level. The study was scheduled for 1 year. RESULTS Ribavirin monotherapy was associated with a decrease in liver enzymes and serum creatinine levels. When proteinuria was present, this decreased or disappeared. There were no significant changes in HCV viremia. There was a significant progression in liver fibrosis with no improvement in inflammation scores. Hemoglobin levels fall dramatically, despite an important support by recombinant erythropoeitin (median, 20,000 IU/wk). In 3 cases, ribavirin therapy had to be stopped. In the control group, after 1 year of follow-up, there was a significant increase in serum alanine aminotransferase and creatinine values. Proteinuria decreased in only 2 of 12 patients (P = 0.03 as compared with group A). CONCLUSION One year of ribavirin monotherapy seems to have, at best, no beneficial effect on liver histology, although it improves liver enzyme levels. Despite its efficiency to dramatically decrease proteinuria, its impact on renal function remains unknown.

Predictive Factors of Anemia within the First Year Post Renal Transplant

Background. The aim of our study was to identify the independent factors that might predict anemia at 6 (M6) and 12 (M12) months posttransplantation. Methods. Postrenal transplant anemia (PTA) was defined as having a hemoglobin (Hb) level below 13 g/dl for men and below 12 g/dL for women. In this study, we included all the recipients who received a renal transplant in 2001 at our department, and for whom the graft was still functioning 1 year later (n=92). Results. Anemia was observed in 78%, 35.5% and 25% of patients at day (D)0 and at M6 and M12, respectively. Iron deficiency was found in 14% of patients at D0 and in 13% of patients at M12. A total of 59.8% of patients had received at least one blood transfusion in the postoperative period, whereas 41.3% of patients had received recombinant erythropoietin (rEpo) therapy within the first months posttransplantation. In multivariate analysis, the independent predictive factors of anemia at M6 were Epo level at D0, initial nephropathy (polycystic kidney disease vs. others), posttransplantation rEpo therapy, hematocrit at M3, platelets at D7, and sirolimus therapy. The independent predictive factors of anemia at M12 were Epo level at D0, platelets at D7, delayed graft function (DGF), creatinine clearance at M12, serum creatinine at M12, and Hb level at M6. Conclusions. The prevalence of PTA was 25% at M12. DGF, renal function at M12, and anemia at M6 were independent risk factors for still having anemia at M12.

Oxalate Nephropathy Associated with Chronic Pancreatitis

BACKGROUND AND OBJECTIVES Enteric overabsorption of oxalate may lead to hyperoxaluria and subsequent acute oxalate nephritis (AON). AON related to chronic pancreatitis is a rare and poorly described condition precluding early recognition and treatment. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We collected the clinical characteristics, treatment, and renal outcome of 12 patients with chronic pancreatitis-associated AON followed in four French renal units. RESULTS Before AON, mild to moderate chronic kidney disease was present in all patients, diabetes mellitus in eight (insulin [n = 6]; oral antidiabetic drugs [n = 2]), and known chronic pancreatitis in only eight. At presentation, pancreas imaging showed gland atrophy/heterogeneity, Wirsung duct dilation, calcification, or pseudocyst. Renal findings consisted of rapidly progressive renal failure with tubulointerstitial profile. Acute modification of glomerular filtration preceded the AON (i.e., diarrhea and diuretics). Increase in urinary oxalate excretion was found in all tested patients and hypocalcemia in nine (<1.5 mmol/L in four patients). Renal biopsy showed diffuse crystal deposits, highly suggestive of oxalate crystals, with tubular necrosis and interstitial inflammatory cell infiltrates. Treatment consisted of pancreatic enzyme supplementation, oral calcium intake, and an oxalate-free diet in all patients and renal replacement therapy in five patients. After a median follow-up of 7 months, three of 12 patients reached end-stage renal disease. CONCLUSION AON is an under-recognized severe crystal-induced renal disease with features of tubulointerstitial nephritis that may occur in patients with a long history of chronic pancreatitis or reveal the pancreatic disease. Extrinsic triggering factors should be prevented.

Reversible posterior leukoencephalopathy syndrome in hepatitis C virus-positive long-term hemodialysis patients.

Chronic hepatitis C virus (HCV) infection is quite prevalent in long-term hemodialysis (HD) patients. Patients who are candidates for renal transplantation might be treated, before grafting, with interferon-alpha (IFN-alpha). Among 39 HCV-positive long-term HD patients treated with IFN-alpha, we observed three cases of reversible posterior leukoencephalopathy syndrome (PLES). PLES included headaches in three patients, confusion in three patients, cortical blindness in two patients, visual hallucinations in one patient, seizures in three patients, and respiratory distress in one patient in a context of fluid overload and severe hypertension in all cases. The three patients were receiving IFN-alpha and recombinant erythropoietin therapies simultaneously for de novo anemia. Contrast-enhanced computed tomography scan or magnetic resonance imaging showed low-density areas in the occipital lobes (in three patients), frontal lobes (in one patient), and temporal lobes (in one patient). After withdrawal of IFN-alpha and recombinant erythropoietin therapies, hemodiafiltration, and symptomatic treatment of seizures and hypertension, PLES was reversible within 1 week in one patient, 10 days in one patient, and 2 months in the third patient. Our case reports show the occurrence of reversible PLES in HCV-positive long-term HD patients treated with IFN-alpha. Physicians caring for HCV-positive long-term HD patients treated with IFN-alpha need to be particularly cautious when these patients receive simultaneously recombinant erythropoietin and when IFN-alpha therapy induces a weight loss, which indicates a reduction in dry weight.