How I diagnose and treat atypical hemolytic uremic syndrome.

Our understanding and management of atypical hemolytic uremic syndrome (aHUS) have dramatically improved in the last decade. aHUS has been established as a prototypic disease resulting from a dysregulation of the complement alternative C3 convertase. Subsequently, prospective nonrandomized studies and retrospective series have shown the efficacy of C5 blockade in the treatment of this devastating disease. C5 blockade has become the cornerstone of the treatment of aHUS. This therapeutic breakthrough has been dulled by persistent difficulties in the positive diagnosis of aHUS, and the latter remains, to date, a diagnosis by exclusion. Furthermore, the precise spectrum of complement-mediated renal thrombotic microangiopathy is still a matter of debate. Nevertheless, long-term management of aHUS is increasingly individualized and lifelong C5 blockade is no longer a paradigm that applies to all patients with this disease. The potential benefit of complement blockade in other forms of HUS, notably secondary HUS, remains uncertain.

Non-plasmapheresis Approaches for Managing Severe Renal Thrombotic Microangiopathy: A Report of 7 Cases.

C5-blockers are the established treatment for complement-mediated hemolytic uremic syndrome (CM-HUS). However, CM-HUS, lacking a definitive test, prompts plasma exchanges as a common first-line therapy, pending further assessments, despite complications and limited evidence in this indication. Recent experts' opinion endorses C5-blockers as the initial treatment for severe renal thrombotic microangiopathy (TMA). This retrospective, single-center study reports a series of 7 patients treated with a plasmapheresis-free approach. All patients presented with severe renal TMA symptoms and low French score and received prompt 900mg eculizumab within a median of 9 hours from admission. Hematological recovery was rapid, and renal function improved in 6 patients within 6.5 days, with a median hospital stay of 16 days. No rescue plasmapheresis was used. We report 7 cases of an early C5-blocker and plasmapheresis-free strategy in severe renal TMA suspicious for CM-HUS, demonstrating promising initial results. Clinical trials are needed to confirm the efficacy and safety of this approach. Addressing the high cost of C5-blocking therapies and exploring cost-effective alternatives is also crucial for broader implementation and accessibility in targeted therapies for adult renal TMA.

Hot Spot of Complement Factor I Rare Variant p.Ile357Met in Patients With Hemolytic Uremic Syndrome.

Atypical hemolytic uremic syndrome (aHUS) is a rare kidney disease due to a dysregulation of the complement alternative pathway. Complement factor I (CFI) negatively regulates the alternative pathway and CFI gene rare variants have been associated to aHUS with a low disease penetrance. We report 10 unrelated cases of HUS associated to a rare CFI variant, p.Ile357Met (c.1071T>G). All patients with isolated p.Ile357Met CFI missense variant were retrospectively identified among patients included between January 2007 and January 2022 in the French HUS Registry. We identified 10 unrelated patients (70% women; median age at HUS diagnosis, 36.5 years) who carry the same rare variant p.Ile357Met in the CFI gene. Seven patients (cases 1-7) presented with aHUS in the native kidney associated with malignant hypertension in 5 patients. None received a C5 inhibitor. Two of these cases occurred in the peripartum period with complete recovery of kidney function, while 5 of these patients reached kidney failure requiring replacement therapy (KFRT). Four patients with KFRT subsequently underwent kidney transplantation. Three later developed C3 glomerulopathy in their kidney graft, but none had aHUS recurrence. Three other patients (cases 8-10) experienced de novo thrombotic microangiopathy after kidney transplantation, precipitated by various triggers. The rare CFI variant p.Ile357Met appears to be a facilitating genetic factor for HUS and for some forms of secondary HUS.

Targeting the Complement Pathway in Kidney Transplantation.

The complement system is paramount in the clearance of pathogens and cell debris, yet is increasingly recognized as a key component in several pathways leading to allograft injury. There is thus a growing interest in new biomarkers to assess complement activation and guide tailored therapies after kidney transplantation (KTx). C5 blockade has revolutionized post-transplant management of atypical hemolytic uremic syndrome, a paradigm of complement-driven disease. Similarly, new drugs targeting the complement amplification loop hold much promise in the treatment and prevention of recurrence of C3 glomerulopathy. Although unduly activation of the complement pathway has been described after brain death and ischemia reperfusion, any clinical attempts to mitigate the ensuing renal insults have so far provided mixed results. However, the intervention timing, strategy, and type of complement blocker need to be optimized in these settings. Furthermore, the fast-moving field of ex vivo organ perfusion technology opens new avenues to deliver complement-targeted drugs to kidney allografts with limited iatrogenic risks. Complement plays also a key role in the pathogenesis of donor-specific ABO- and HLA-targeted alloantibodies. However, C5 blockade failed overall to improve outcomes in highly sensitized patients and prevent the progression to chronic antibody-mediated rejection (ABMR). Similarly, well-conducted studies with C1 inhibitors in sensitized recipients yielded disappointing results so far, in part, because of subtherapeutic dosage used in clinical studies. The emergence of new complement blockers raises hope to significantly reduce the negative effect of ischemia reperfusion, ABMR, and nephropathy recurrence on outcomes after KTx.

[Change in the prevention of kidney stones]. / Lithiase rénale, un changement de paradigme?

Kidney stone is one of the most frequent disorders of the urinary tract. Once the stone has passed, the management should be oriented on prevention. If changes in lifestyle and diet should be implemented in a true therapeutic education of the patient, prescription of drugs has been recently challenged by the NOSTONE trial. This randomized controlled trial did not show any benefit of hydrochlorothiazide in the prevention of recurrence of kidney stone event in patients with calcium-containing stone. Therefore, prescription of thiazide in the sole purpose of decreasing kidney stone recurrence should be limited and the risk/benefit of this treatment should be carefully balanced for each case.

La maladie rénale lithiasique est une des affections les plus fréquentes de l'axe urinaire. Une fois l'expulsion du calcul obtenue, la prise en charge est orientée sur la prévention. Si les modifications diététiques et comportementales doivent être implémentées dans le cadre d'une véritable éducation thérapeutique, la prescription de traitements médicamenteux préventifs est remise en question par l'étude NOSTONE. Cette étude randomisée contrôlée n'a pas montré de bénéfice de l'hydrochlorothiazide dans la prévention de la récidive des calculs à contenu calcique. Dès lors, la prescription de thiazide en monothérapie dans le but de diminuer les récidives de calculs doit être limitée et le risque/bénéfice soigneusement évalué dans chaque cas.

Glomerular diseases in pregnancy: pragmatic recommendations for clinical management.

Our understanding of the various aspects of pregnancy in women with kidney diseases has significantly improved in the last decades. Nevertheless, little is known about specific kidney diseases. Glomerular diseases are not only a frequent cause of chronic kidney disease in young women, but combine many challenges in pregnancy: immunologic diseases, hypertension, proteinuria, and kidney tissue damage. An international working group undertook the review of available current literature and elicited expert opinions on glomerular diseases in pregnancy with the aim to provide pragmatic information for nephrologists according to the present state-of-the-art knowledge. This work also highlights areas of clinical uncertainty and emphasizes the need for further collaborative studies to improve maternal and fetal health.

[Management of hyperuricemia in chronic kidney disease]. / Hyperuricémie et maladie rénale : prise en charge.

Hyperuricemia is often encountered as glomerular filtration rate decreased. It is associated with a more rapid decline of the renal function, but causality has not been demonstrated. Recent studies showed that treatment of hyperuricemia did not affect the progression in chronic kidney disease (CKD) patients. Thus, treatment with hypouricemic drugs of patients suffering of CKD and displaying asymptomatic hyperuricemia is not recommended. However, patients with CKD present often with acute flairs of gout, which might be difficult to treat. Therapeutic options are discussed in this article.

Une hyperuricémie apparaît précocement en cas de diminution de la filtration glomérulaire et de maladie rénale chronique. Elle est associée à un déclin plus rapide de la fonction rénale, mais un lien de causalité n'a pas été démontré. Plusieurs études récentes n'ont pas montré d'effet bénéfique d'un traitement hypo-uricémiant sur l'évolution de la fonction rénale. Ainsi, en cas d'hyper uricémie asymptomatique chez un patient souffrant de maladie rénale chronique, un traitement hypo-uricémiant n'est pas indiqué. Cependant, les patients souffrant de maladie rénale chronique font plus fréquemment des crises de goutte, et leur prise en charge est complexe car la maladie est à la fois plus résistante au traitement et les options thérapeutiques sont limitées. Celles-ci sont revues dans cet article.

[Hypertension after kidney transplantation]. / Hypertension après transplantation rénale.

Kidney transplantation is the treatment of choice for end-stage renal disease. While graft survival has considerably improved with current immunosuppressive strategies, long-term prognosis is dependent on cardiovascular complications. There is a high prevalence of arterial hypertension after kidney transplantation. Hypertension can be associated with traditional risk factors or directly linked with the anatomy and the function of the kidney allograft, as well as with the immunosuppressive treatment. Current blood pressure targets are <130/80 mmHg, but there is a lack of evidence regarding the impact on cardiovascular and graft outcomes. In this review, we discuss the epidemiology, the causes as well as the management of hypertension after kidney transplantation.

La transplantation rénale est le traitement de choix de l'insuffisance rénale terminale. Si la survie des greffons s'est considérablement améliorée avec les traitements immunosuppresseurs actuels, le pronostic à long terme dépend en grande partie des complications cardiovasculaires. L'hypertention artérielle (HTA) est très fréquente après une transplantation rénale. Elle peut être associée aux facteurs de risque traditionnels ou être plus spécifiquement en lien avec l'anatomie et la fonction du greffon ainsi qu'avec les médicaments antirejet. Les cibles tensionnelles recommandées sont des valeurs < 130/80 mmHg, mais les évidences manquent concernant l'impact sur les complications cardiovasculaires et la survie du greffon. Dans cet article, nous discutons l'épidémiologie, les causes et la prise en charge de l'HTA après transplantation rénale.

Upfront use of eculizumab to treat early acute antibody-mediated rejection after kidney allotransplantation and relevance for xenotransplantation.

Acute antibody-mediated rejection (AMR) early after transplant remains a challenge, both in allotransplantation and in xenotransplantation. We report the case of an early and severe acute AMR episode in a kidney transplant recipient that was successfully treated with upfront eculizumab. A 58-year-old woman had been on dialysis since 2014. She underwent a first kidney transplant in 2018 with primary non-function and received several blood transfusions. Postoperatively, she developed anti-HLA antibodies. One year later, she received a second allograft from a deceased donor. At day 0, there was only one preformed low-level donor-specific antibody (DSA) anti-DQ7. After initial excellent allograft function, serum creatinine increased on days 7-9, and this was associated with oligo-anuria. On day 7, there was an increase in her DSA anti-DQ7 and 4 de novo DSA had developed at high MFI values. Allograft biopsy showed severe active AMR with diffuse C4d deposits in peritubular capillaries. The early acute AMR episode was treated with upfront eculizumab administration (2 doses) with efficient CH50 blockade (< 10% CH50). Rituximab was also administered on day 12, and intravenous immunoglobulin (IVIG) was given over the following days. There was an excellent clinical response to eculizumab administration. Eculizumab administration rapidly reversed the acute AMR episode without the need for plasmapheresis. Rituximab and IVIG were also used as B-cell immunomodulators to decrease DSA. Blocking efficiently the terminal complement pathway may become a useful strategy to treat acute AMR in sensitized recipients of allografts, and possibly in recipients of discordant xenografts.

[Post-transplantation diabetes in kidney transplant: from the diabetologist point of view]. / Diabète post-transplantation rénale: le point de vue du diabétologue.

Post-transplantation diabetes (PTDM) exposes to increased morbidity (cardiovascular or infectious complications, early graft dysfunction) and to a risk of premature death. Recognition of risk factors is essential for early and individualized care. The management of a PTDM requires the use of oral antidiabetic treatments (metformin or DPP4 inhibitors) or GLP1 receptor agonists for their favorable effects on weight and kidney that seem ideal in this context. Corticosteroid-induced diabetes or the rare occurrence of diabetic ketoacidosis require insulin therapy. In the long term, the main objective remains to integrate PTDM treatment in a more comprehensive management, targeting the reduction of cardiovascular risk of vulnerable transplant patients.

Le diabète post-transplantation (PTDM) expose le patient à une morbidité accrue (cardiovasculaire, infectieuse ou dysfonction précoce du greffon), ainsi qu'à un risque de décès prématuré. La reconnaissance des facteurs de risque est primordiale pour une prise en charge précoce et individualisée. La prise en charge d'un PTDM d'apparition progressive recourt à l'utilisation d'antidiabétiques oraux (metformine ou inhibiteurs de la dipeptidyl peptidase 4) ou aux agonistes du récepteur du glucagon-like peptide-1 dont l'effet pondéral et néphroprotecteur semble idéal dans ce contexte. Un diabète cortico-induit ou, plus rare, une acidocétose aiguë seront traités par une insulinothérapie précoce. À long terme, l'objectif reste d'intégrer le traitement du PTDM dans une prise en charge plus globale ciblant la réduction du risque cardiovasculaire de ces patients transplantés fragiles.

[Challenges in managing diabetes in chronic hemodialysis]. / Défis dans la prise en charge du diabète en hémodialyse chronique.

Hemodialysis (HD) centers are facing an increasing number of patients with diabetes. These cases require an intensive multidisciplinary approach of the consequences of renal failure, glycemic control and nutrition and the management of frequent co-morbidities, in particular the diabetic foot. A major challenge is to decrease glycemic variability and the risk of hypoglycemia. Because of increased risk of hypoglycemia-associated mortality, the HbA1C target is loosened in the majority of HD patients. Continuous glucose monitoring technology has identified important glycemic fluctuations during and after dialysis. However, their reliability in HD needs to be improved. New therapeutic pathways that decrease glucose excursions and hypoglycemia, such as GLP1 receptor agonists and sensor-coupled insulin pumps, have yet to be validated in HD.

Les centres d'hémodialyse (HD) sont confrontés à un nombre croissant de patients diabétiques. Leur prise en charge multidisciplinaire tient compte de l'insuffisance rénale, du contrôle glycémique, de la nutrition et des comorbidités fréquentes, en particulier le pied diabétique. La réduction de la variabilité glycémique et des hypoglycémies qui sont associées à une mortalité accrue reste un défi. La cible de l'HbA1C est assouplie chez la majorité des patients. L'usage du contrôle en continu de la glycémie permet d'identifier les fluctuations glycémiques per et interdialytiques importantes. Sa fiabilité doit cependant être améliorée en HD. Les nouvelles voies thérapeutiques qui diminuent les excursions glycémiques et le risque d'hypoglycémie comme les GLP1 agonistes et les pompes à insuline couplées aux sensors restent à valider en HD.

[Preventive measures of acute renal failure]. / Mesures préventives de l'insuffisance rénale aiguë.

Many conditions can lead to acute renal failure. Some of them are intrinsic renal diseases whose natural history cannot be anticipated. On the other hand, others correspond to external aggressions driven by various hemodynamic or toxic events. To some extent, these can be partially prevented by relatively simple measures. The recognition of these situations which may benefit from a preventive strategy can significantly reduce morbidity or mortality associated with the incidence of acute renal failure.

Optimal culture incubation time in orthopedic device-associated infections: a retrospective analysis of prolonged 14-day incubation.

Accurate diagnosis of orthopedic device-associated infections can be challenging. Culture of tissue biopsy specimens is often considered the gold standard; however, there is currently no consensus on the ideal incubation time for specimens. The aim of our study was to assess the yield of a 14-day incubation protocol for tissue biopsy specimens from revision surgery (joint replacements and internal fixation devices) in a general orthopedic and trauma surgery setting. Medical records were reviewed retrospectively in order to identify cases of infection according to predefined diagnostic criteria. From August 2009 to March 2012, 499 tissue biopsy specimens were sampled from 117 cases. In 70 cases (59.8%), at least one sample showed microbiological growth. Among them, 58 cases (82.9%) were considered infections and 12 cases (17.1%) were classified as contaminations. The median time to positivity in the cases of infection was 1 day (range, 1 to 10 days), compared to 6 days (range, 1 to 11 days) in the cases of contamination (P < 0.001). Fifty-six (96.6%) of the infection cases were diagnosed within 7 days of incubation. In conclusion, the results of our study show that the incubation of tissue biopsy specimens beyond 7 days is not productive in a general orthopedic and trauma surgery setting. Prolonged 14-day incubation might be of interest in particular situations, however, in which the prevalence of slow-growing microorganisms and anaerobes is higher.

Prevalence of hypertension and uncontrolled hypertension after solid organ transplantation: a 5-year follow-up of the Swiss Transplant Cohort Study.

OBJECTIVE: Hypertension (HTN) increases cardiovascular risk and is a frequent finding across all solid organ transplant recipients. We describe the prevalence of HTN and uncontrolled HTN, as well as details on pharmacologic treatment of HTN across solid organs transplant recipients up to five years after transplantation. METHODS: This retrospective study is nested in the prospective Swiss Transplant Cohort Study (www.stcs.ch) that includes kidney, heart, lung, and liver transplantation. Data extraction from 2008 to 2019 was used for this study and follow-up data at 6, 12 and 60 months was analyzed. RESULTS: A total of 3865 transplant recipients were included for analysis. The prevalence of HTN at 6 and 60 months was 88.9% and 90.4% in kidney (P = 0.21), 61.8% and 76.1% in liver (P < 0.01), 72.6% and 84.9% in lung (P < 0.01), and 89.3% and 85.8% in heart (P = 0.33) transplant recipients, respectively. The prevalence of uncontrolled HTN at 6 and 60 months was 40.3% and 38.9% in kidney (P = 0.48), 21.2% and 30.5% in liver (P = 0.05), 26.0% and 36.8% in lung (P = 0.03) and 38.9% and 18.5% in heart (P < 0.01) transplant recipients, respectively. At 12 months, compared to heart transplant recipients, kidney [odds ratio (OR) = 1.6, 95% confidence interval (CI) 1.1-2.1], liver (OR = 1.7, 95% CI 1.1-2.6) and lung (OR = 2.6, 95% CI 1.6-4.0) transplant recipients had a higher likelihood of presenting with uncontrolled HTN. CONCLUSION: HTN prevalence after solid organ transplantation is high. Uncontrolled and untreated HTN remain a major issue post transplantation, particularly in organ recipients not necessarily suffering from cardiovascular diseases such as liver or lung transplant recipients.

Thrombotic Microangiopathy as an Emerging Complication of Viral Vector-Based Gene Therapy.

Gene therapy has brought tremendous hope for patients with severe life-threatening monogenic diseases. Although studies have shown the efficacy of gene therapy, serious adverse events have also emerged, including thrombotic microangiopathy (TMA) following viral vector-based gene therapy. In this review, we briefly summarize the concept of gene therapy, and the immune response triggered by viral vectors. We also discuss the incidence, presentation, and potential underlying mechanisms, including complement activation, of gene therapy-associated TMA. Further studies are needed to better define the pathogenesis of this severe complication of gene therapy, and the optimal measures to prevent it.

The Rational Use of Complement Inhibitors in Kidney Diseases.

The development of complement inhibitors represented one of the major breakthroughs in clinical nephrology in the last decade. Complement inhibition has dramatically transformed the outcome of one of the most severe kidney diseases, the atypical hemolytic uremic syndrome (aHUS), a prototypic complement-mediated disorder. The availability of complement inhibitors has also opened new promising perspectives for the management of several other kidney diseases in which complement activation is involved to a variable extent. With the rapidly growing number of complement inhibitors tested in a rapidly increasing number of indications, a rational use of this innovative and expensive new therapeutic class has become crucial. The present review aims to summarize what we know, and what we still ignore, regarding complement activation and therapeutic inhibition in kidney diseases. It also provides some clues and elements of thoughts for a rational approach of complement modulation in kidney diseases.

Spectrum of Kidney Involvement in Patients with Myelodysplastic Syndromes.

INTRODUCTION: Myelodysplastic syndromes (MDS) are characterized by a high prevalence of associated autoimmune manifestations. Kidney involvement has been rarely reported in MDS patients. We report on the spectrum of kidney pathological findings in MDS patients. METHODS: We retrospectively identified MDS patients who had undergone a kidney biopsy between 2001 and 2019 in nine Swiss and French nephrology centres. RESULTS: Nineteen patients (median age 74 years [63-83]) were included. At the time of kidney biopsy, eleven (58%) patients had extra-renal auto-immune manifestations and sixteen (84%) presented with acute kidney injury. Median serum creatinine at diagnosis was 2.8 mg/dL [0.6-8.3] and median urinary protein to creatinine ratio was 1.2 g/g [0.2-11]. Acute tubulo-interstitial nephritis (TIN) was present in seven (37%) patients. Immunofluorescence study in one patient with acute TIN disclosed intense IgG deposits along the tubular basement membrane and Bowman's capsule. Other kidney pathological features included ANCA-negative pauci-immune necrotizing and crescentic glomerulonephritis (n = 3), membranous nephropathy (n = 2), IgA nephropathy (n = 1), IgA vasculitis (n = 1), immunoglobulin-associated membrano-proliferative glomerulonephritis type I (n=1), crescentic C3 glomerulopathy (n = 1), fibrillary glomerulonephritis (n = 1) and minimal change disease (n = 1). Eleven (58%) patients received immunosuppressive treatments, among whom one developed a severe infectious complication. After a median follow-up of 7 month [1-96], nine (47%) patients had chronic kidney disease stage 3 (n = 6) or 4 (n = 3) and five (26%) progressed to end-stage kidney disease. Three patients died. CONCLUSIONS: MDS are associated to several autoimmune kidney manifestations, predominantly acute TIN. MDS are to be listed among the potential causes of autoimmune TIN.

Water-Soluble Vitamin Levels and Supplementation in Chronic Online Hemodiafiltration Patients.

INTRODUCTION: Supplementation of water-soluble vitamins is a common practice in hemodialysis patients, but dosages are largely based on conventional hemodialysis techniques. The aim of this study was to assess the status of water-soluble vitamins in patients on hemodiafiltration (HDF), and attempt to determine optimal dose of vitamin supplements. METHODS: This monocentric study included 40 patients on thrice-weekly chronic HDF. At baseline, all patients received 2 tablets of Dialvit containing B and C vitamins after each dialysis session. Predialysis samples of B and C vitamins were measured in both blood (n = 40) and a subgroup of dialysate (n = 6) samples. A second blood sample was obtained in 24 patients 3 months after dose adjustment of the vitamin supplement. RESULTS: At baseline, B-vitamin levels were high with, respectively, 0.4%, 10.0%, and 89.6% of patients in the low, normal, and high reference range. For vitamin C, most patients were in the normal range (5.0%, 82.5%, and 12.5% in low, normal, and high reference range). Three months after dose reduction, B vitamin levels decreased but stayed mostly at or above the normal range (1.4%, 25.7%, 72.9% in low, normal, and high reference range). Three patients (12.5%) developed vitamin C deficiency on low-dose substititon. CONCLUSION: This study shows that the levels of most vitamins are above the normal range in patients on HDF receiving a classic dose of vitamin supplements, vitamin C excepted. Our study suggests that the classic dose of postdialysis vitamin B supplements may be reduced.