Severe Thrombotic Microangiopathy Research Articles

Post-COVID-19 complement-mediated TMA: A case report.

Systemic COVID-19 disease is associated with a variety of organ involvement in infected patients. A rarely reported complication is the induction of complement-mediated thrombotic microangiopathy (TMA). TMA is an extremely rare pathological condition that results in thrombosis in capillaries and small arterioles, due to an endothelial injury. It is often combined with thrombocytopenia, Coombs-negative hemolytic anemia, and end-organ damage. This case involves a patient who was admitted to our hospital for the purpose of diagnosis and treatment of acute kidney injury (AKIN 3) with severe proteinuria after a preceding SARS-CoV-2 infection. A 77-year-old male patient had COVID-19 pneumonia in January 2021 with the need of high-flow oxygen therapy in the intensive care unit. In March 2021, he was hospitalized again due to elevated serum creatinine levels and proteinuria. The patient exhibited normal vital parameters. A renal biopsy showed severe TMA. A diagnosis of COVID-19-associated TMA was made, and treatment with high-dose glucocorticoid therapy and plasma exchange was initiated. Additionally, therapy with eculizumab was established. Unfortunately, the kidney failure was initially progressive, so that hemodialysis (HD) was temporarily necessary. In May 2021, kidney function recovered to an estimated glomerular filtration rate of ~ 30 mL/min/1.73m2 corresponding to chronic kidney disease stage 3bA3 - 4A3. COVID-19-associated TMA is an extremely rare disease. TMA may be a possible long-term complication with the risk of end-stage renal disease if not properly diagnosed and treated.

Atypical Presentations of Pediatric-acquired Thrombotic Thrombocytopenic Purpura.

Immune thrombotic thrombocytopenic purpura (iTTP) in children is a rare, severe thrombotic microangiopathy. This condition is characterized by microangiopathic hemolytic anemia, severe thrombocytopenia, and organ ischemia due to reduced activity of the von Willebrand factor-cleaving protease ADAMTS13. A retrospective case series evaluating data collected from the medical files of 4 children diagnosed with iTTP. The presented case series depicts a variety of iTTP presentations: 1 case of primary iTTP, 1 case induced by Shiga toxin, 1 associated with RAS-associated autoimmune leukoproliferative disease (RALD), and 1 initial manifestation of systemic lupus erythematosus (SLE). Notably, 2 patients recovered without undergoing plasma exchange. Early ADAMTS13 testing in children with unexplained hemolysis or thrombocytopenia is crucial. The diverse underlying causes, including infections and autoimmune disorders, underscore the complexity of iTTP in the pediatric population. These cases highlight the necessity for personalized treatment approaches that consider each patient's unique clinical situation and potential alternatives or modifications to conventional therapeutic regimens.

Post-transplant CFHR5 mutation-related atypical HUS: The need for pre-transplant diagnosis

Atypical hemolytic uremic syndrome (aHUS) is a rare form of thrombotic microangiopathy (TMA) affecting multiple organs and can be sporadic or familial. It is most commonly caused by dysregulation of the alternative complement pathway. aHUS can occur at any age with a high rate of progression to end-stage kidney disease. We describe the case of a 24-year-old man with chronic kidney disease, severe hypertension, and antineutrophilic antibody by IF positive. On biopsy, diffuse global glomerulosclerosis with TMA and IF findings of full house pattern suggestive of lupus nephritis were present. Considering a lupus nephritis case, after 2 years of hemodialysis underwent live-related renal transplant (Father Donor). Immediate post-transplant period developed severe cortical necrosis and TMA. An etiological workup was done to ascertain the cause of post-transplant TMA. After excluding common causes of antibody-mediated rejection (C4d and donor-specific alloantibody neg), calcineurin inhibitor toxicity, and infection, we detected an abnormal complement CFHR5 mutation with an autosomal dominant pattern of inheritance. Pre-transplant diagnosis could have prevented taking the kidney from the father for transplant and further prevented recurrence. Systemic lupus erythematosus and TMA both can have alternate complement pathway dysregulation leading to full house IF pattern and misdiagnosis.

#5386 ONCO-NEPHROLOGY: THE ROLE OF KIDNEY BIOPSY IN THE MANAGEMENT OF SIDE EFFECTS OF TARGETED THERAPIES

Abstract Background and Aims The introduction of innovative therapies, resulting from revisiting cancer as a disease of the immune system, has changed the scenario of complications. These new classes of drugs, such as targeted therapies and immune checkpoint inhibitors, assure substantial advantages in cancer therapy, despite some side affecting various organs, including the kidney. Histological evaluations of kidney disorders induced by targeted/immunotherapy are limited. Method In this study we examined the histological features of patients treated with new cancer agents who underwent kidney biopsy for new onset kidney failure and/or urinary abnormalities. Results The cohort included 30 adult patients. The most frequently administered therapies were immunotherapy (30%), targeted therapy (26.7%), immunotherapy plus targeted therapy (13.3%), immunotherapy plus chemotherapy (13.3%), targeted therapy plus chemotherapy (16.7%). The most common histological finding was tubular interstitial nephritis (30%) that was associated with acute tubular necrosis in 4 cases, and thrombotic microangiopathy (23.3%). After kidney biopsy, 16 of the 30 patients were treated according to the histological diagnosis. Fourteen patients were treated with steroids. One patient with membranous nephropathy was treated with a single dose of rituximab. A patient with severe thrombotic microangiopathy requiring dialysis received a treatment with eculizumab for 3 months. Overall some renal response was obtained in all patients treated with glucocorticoids, while complete kidney response was achieved in the patient treated with rituximab. Cancer treatment was resumed without change in 21 out of 30 patients. Conclusion Kidney biopsy is critical for the management of kidney toxicities and should be strongly encouraged for patients showing adverse kidney effects of novel cancer agents.

Thrombotic thrombocytopenic purpura in a patient on long-term alpha-interferon therapy for essential thrombocythemia: a case report

BackgroundThrombotic thrombocytopenic purpura (TTP) is rare and severe thrombotic microangiopathy characterized by thrombocytopenia, hemolytic anemia, and renal dysfunction. In contrast, essential thrombocythemia (ET) is a myeloproliferative disease associated with an abnormal increase in platelet numbers. Previous studies reported several cases of the development of ET in patients with TTP. However, the case of an ET patient complicated with TTP has not been previously reported. In this case study, we present a patient with TTP who was previously diagnosed with ET. Therefore, to the best of our knowledge, this is the first report of TTP in ET.Case presentationA 31-year-old Chinese female who was previously diagnosed with ET presented with anemia and renal dysfunction. The patient had been on long-term treatment with hydroxyurea, aspirin, and alpha interferon (INF-α) for ten years. The diagnosis of TTP was confirmed by clinical features, schistocytes noted on the peripheral blood smear, and lower ADAMTS13 activity (8.5%), together with the renal biopsy results. INF-α was discontinued, and the patient was then treated with plasma exchange and corticosteroids. After one year of follow-up, the patient had a normal hemoglobin level and platelet numbers, and her ADAMTS13 activity had improved. However, the patient’s renal function remains impaired.ConclusionsWe report a case of an ET patient complicated with TTP that was possibly due to INF-α, highlighting the potential complications associated with long-term ET therapy. The case also highlights the importance of considering TTP in patients with pre-existing ET who present with anemia and renal dysfunction, extending the spectrum of known studies.

The need for kidney biopsy in the management of side effects of target and immunotherapy.

The introduction of innovative therapies, resulting from revisiting cancer as a disease of the immune system, has changed the scenario of complications. These new classes of drugs, such as targeted therapies and immune checkpoint inhibitors, assure substantial advantages in cancer therapy, despite some side effects affecting various organs, including the kidney. Histological evaluations of kidney disorders induced by targeted/immunotherapy are limited. In this study we examined the histological features of patients treated with new cancer agents who underwent a kidney biopsy for new onset kidney failure and/or urinary abnormalities. The cohort included 30 adult patients. The most frequently administered therapies were immunotherapy (30%), targeted therapy (26.7%), immunotherapy plus targeted therapy (13.3%), immunotherapy plus chemotherapy (13.3%), targeted therapy plus chemotherapy (16.7%). The most common histological finding was tubular interstitial nephritis (30%) that was associated with acute tubular necrosis in 4 cases, and thrombotic microangiopathy (23.3%). After kidney biopsy, 16 of the 30 patients were treated according to the histological diagnosis. Fourteen patients were treated with steroids. One patient with membranous nephropathy was treated with a single dose of rituximab. A patient with severe thrombotic microangiopathy requiring dialysis received a treatment with eculizumab for 3 months. Overall some renal response was obtained in all patients treated with glucocorticoids, while complete kidney response was achieved in the patient treated with rituximab. Cancer treatment was resumed without change in 21 out of 30 patients. Kidney biopsy is critical for the management of kidney toxicities and should be strongly encouraged for patients showing adverse kidney effects of novel cancer agents.

Is Endothelial Activation a Critical Event in Thrombotic Thrombocytopenic Purpura?

Thrombotic thrombocytopenic purpura (TTP) is a severe thrombotic microangiopathy. The current pathophysiologic paradigm suggests that the ADAMTS13 deficiency leads to Ultra Large-Von Willebrand Factor multimers accumulation with generation of disseminated microthrombi. Nevertheless, the role of endothelial cells in this pathology remains an issue. In this review, we discuss the various clinical, in vitro and in vivo experimental data that support the important role of the endothelium in this pathology, suggesting that ADAMTS13 deficiency may be a necessary but not sufficient condition to induce TTP. The "second hit" model suggests that in TTP, in addition to ADAMTS13 deficiency, endogenous or exogenous factors induce endothelial activation affecting mainly microvascular cells. This leads to Weibel-Palade bodies degranulation, resulting in UL-VWF accumulation in microcirculation. This endothelial activation seems to be worsened by various amplification loops, such as the complement system, nucleosomes and free heme.

X-linked C1GALT1C1 mutation causes atypical hemolytic uremic syndrome.

Hemolytic-uremic syndrome (HUS), mostly secondary to infectious diseases, is a common cause of acute kidney injury in children. It is characterized by progressive acute kidney failure due to severe thrombotic microangiopathy, associated with nonimmune, Coombs-negative hemolytic anemia and thrombocytopenia. HUS is caused mostly by Shiga toxin-producing E. Coli, and to a lesser extent by Streptococcus pneumonia. In Streptococcus pneumonia HUS (pHUS), bacterial neuraminidase A exposes masked O-glycan sugar residues on erythrocytes, known as the T antigen, triggering a complement cascade causing thrombotic microangiopathy. Atypical HUS (aHUS) is a life-threatening genetic form of the disease, whose molecular mechanism is only partly understood. Through genetic studies, we demonstrate a novel X-linked form of aHUS that is caused by a de-novo missense mutation in C1GALT1C1:c.266 C > T,p.(T89I), encoding a T-synthase chaperone essential for the proper formation and incorporation of the T antigen on erythrocytes. We demonstrate the presence of exposed T antigen on the surface of mutant erythrocytes, causing aHUS in a mechanism similar to that suggested in pHUS. Our findings suggest that both aHUS caused by mutated C1GALT1C1 and pHUS are mediated by the lectin-complement-pathway, not comprehensively studied in aHUS. We thus delineate a shared molecular basis of aHUS and pHUS, highlighting possible therapeutic opportunities.

MO071: Hemolysis is Associated with Altered Heparan Sulfate of Endothelial Glycocalyx And with Local Complement Activation in Thrombotic Microangiopathies

Abstract BACKGROUND AND AIMS The complement system plays a key role in the pathophysiology of renal thrombotic microangiopathies (TMA), as illustrated by atypical hemolytic uremic syndrome (HUS) characterized by a high rate of mutations in complement proteins. However, complement abnormalities are not fully sufficient to drive to TMA lesions. Among other suspected pathophysiological actors, we hypothesize that the alteration of heparan sulfate (HS) of endothelial glycocalyx—a cell membrane glycoaminoglycans and glycoproteins matrix able of regulating complement by binding factor H—may play a significant role. METHOD We recorded clinical and histological features in native kidney biopsies from a monocentric retrospective cohort of 72 TMA-patients. Glomerular HS integrity and local complement activation markers (C3 and C5b9 staining) were analyzed by immunofluorescence (IF) and immunohistochemistry. Using an in vitro endothelial cells model (human umbilical vein endothelial cells, HUVECs), we studied the impact of heme exposure (30’, 37°C)—a major product of hemolysis—on endothelial HS integrity by IF and flow cytometry (FCM). Heme-induced HS disruption was studied by slot blot of HS core-protein Syndecan (SDC) 1 and 4 in cells supernatant. Artificial enzymatic degradation of HS was achieved after exposure of HUVECs to a combination of heparinases I, II and III (30', 37°C), and we studied its effect on the ability of the HS-free cell membrane to locally activate complement by analyzing C3b deposition by IF and FCM, and the release of complement anaphylatoxins C3a and soluble attack complex membrane s-C5b9 in the cell supernatants by ELISA. The HS remodeling process induced by heme exposure (16 h, 37°C) were indirectly analyzed via a transcriptional profiling of the expression of the key enzymes involved in HS synthesis by RT–qPCR. RESULTS Glomerular HS staining decreased in 57 TMA-patients (79%), moderately (2+) or strongly (0–1+) in 20 (28%) and 37 (51%) cases, respectively. Reduced HS density was significantly associated with hemolysis at the time of biopsy (P = 0.008) and local complement activation (C3d and/or C5b-9 deposits, P < 0.001). Hemolysis at the time of biopsy was associated with more severe glomerular TMA lesions (P = 0.025), the presence of vascular thrombi (P = 0.007) and local complement activation (C3d and/or C5b-9 deposits, P = 0.006). On endothelial cells (HUVECs), we confirmed that HS expression was decreased after heme exposure in IF and FCM (P < 0.01). Coherently, HS core-proteins SDC-1 and 4 were significantly increased in HUVECs supernatant (P < 0.05), suggesting a negative heme-driven impact on HS integrity. Artificial HS degradation increased C3b membrane deposition on HUVECs on average ∼ 3 fold by FCM and ∼ 10 by IF, and we observed an increased release of complement C3a and s-C5b9 in cells supernatant (P < 0.05). Finally, we showed that prolonged exposure to heme induced a decreased of genic expression of C5-Epimerase and an increase in 6-OST1 and 3-OST1 expression (P < 0.05), the very three crucial genes of HS remodeling specifically and sequentially involved in the generation of anti-thrombin pattern, the well-known key regulator of the HS/heparin-driven inhibition of coagulation. CONCLUSION This study highlights the impact of hemolysis on the integrity of endothelial glycocalyx HS, both in kidney biopsy of TMA-patients and in an in vitro endothelial cell model, and suggests that acute alteration of HS is a mechanism of heme-induced complement activation. The endothelial glycocalyx appears then to be an important key in the understanding of TMA and could lead to the development of therapeutics targeting its preservation and/or reconstitution, in order to better control the disease.

Monoclonal gammopathy of renal significance presenting with cryoglobulinaemia type I associated severe thrombotic microangiopathy

ABSTRACTWe report a 53-year-old man who presented with acute renal failure. His medical history revealed a spondyloarthropathy, for which secukinumab was started recently, and a monoclonal gammopathy of unknown significance. Kidney function deteriorated despite the withdrawal of secukinumab and dialysis was started. In the serum, type 1 cryoglobulins were present and a kidney biopsy showed ischaemic glomeruli, with thrombosis of the larger interlobular arteries. Other causes of thrombotic microangiopathy were excluded. Bone marrow immunophenotyping showed 1% monoclonal plasma cells. A diagnosis of monoclonal gammopathy of renal significance was made. Haematological treatment resulted in haematological and renal response.

Síndrome hemolítico urémico asociado a toxina Shiga con hipocomplementemia en edad atípica. Caso clínico

The Shiga toxin associated (Stx) hemolytic uremic syndrome (HUS) is an important cause of acute renal failure (ARF) and the most common cause of thrombotic microangiopathy (TMA) in pediatrics. Primary atypical HUS (aHUS) is a rare disease due to a genetic defect in the alternative complement pathway. Both diseases may share clinical and laboratory elements, making differential diagnosis difficult, such as the presence of diarrhea in aHUS or complement alterations in HUS-Stx. The treatment and prognosis of both diseases is completely different. We report a 15-year-old male with severe HUS. After a self-limited diarrheal syndrome, he had a severe TMA and ARF, requiring renal replacement therapy. An extensive etiological study was carried out, ruling out the main causes of TMA. Alterations in complement factors were observed. Finally, the diagnosis of HUS-Stx was established. The patient evolved favorably with recovery of renal function.

IgM Autoantibodies to Complement Factor H in Atypical Hemolytic Uremic Syndrome.

Atypical hemolytic uremic syndrome (aHUS), a severe thrombotic microangiopathy, is often related to complement dysregulation, but the pathomechanisms remain unknown in at least 30% of patients. Researchers have described autoantibodies to complement factor H of the IgG class in 10% of patients with aHUS but have not reported anti-factor H autoantibodies of the IgM class. In 186 patients with thrombotic microangiopathy clinically presented as aHUS, we searched for anti-factor H autoantibodies of the IgM class and those of the IgG and IgA classes. We used immunochromatography to purify anti-factor H IgM autoantibodies and immunoenzymatic methods and a competition assay with mapping mAbs to characterize interaction with the target protein. We detected anti-factor H autoantibodies of the IgM class in seven of 186 (3.8%) patients with thrombotic microangiopathy presented as aHUS. No association was observed between anti-factor H IgM and homozygous deletions involving CFHR3-CFHR1. A significantly higher proportion of patients with bone marrow transplant-related thrombotic microangiopathy had anti-factor H IgM autoantibodies versus other patients with aHUS: three of 20 (15%) versus four of 166 (2.4%), respectively. The identified IgM autoantibodies recognize the SCR domain 19 of factor H molecule in all patients and interact with the factor H molecule, inhibiting its binding to C3b. Detectable autoantibodies to factor H of the IgM class may be present in patients with aHUS, and their frequency is six-fold higher in thrombotic microangiopathy forms associated with bone marrow transplant. The autoantibody interaction with factor H's active site may support an autoimmune mechanism in some cases previously considered to be of unknown origin.

New in the differential diagnosis of different variants of thrombotic microangiopathies in obstetrics

All variants of thrombotic microangiopathy (TMA) in obstetric practice develop in an avalanche-like manner and require a rapid decision on the choice of treatment tactics. Although all these diseases have similar features, typical of the TMA syndrome as a whole, they are separate diseases with differing etiology and pathogenesis. Because the manifestations of TMA are almost identical in the different diseases, they may all imitate pre-eclampsia and the therapeutic approaches differ, a differential diagnosis is essential and often determines the prognosis.The differential diagnostic search between the different TMA variants that can develop in pregnancy is described, as the prognosis of life often depends on the correct diagnosis. The main differences between pre-eclampsia/HELLP syndrome and life-threatening conditions such as atypical hemolytic-uremic syndrome, thrombotic thrombocytopenic purpura and catastrophic antiphospholipid syndrome are considered. Algorithms of diagnostic search are proposed. Attention is drawn to the fact that existing algorithms for the diagnosis of severe TMA prior to ADAMTS 13 results, based on the severity of thrombocytopenia and azotemia as well as scoring during pregnancy can serve as a guide, but not as a defining feature of the diagnosis.The key to the differential diagnosis is the effect of delivery on the regression of TMA: if hemolysis and thrombocytopenia decrease after delivery, one can speak of ‘pure’ pre-eclampsia (PE) or HELLP-syndrome. If persistent or increasing, thrombotic thrombocytopenic purpura (TTP) and aHUS should be considered. With an ADAMTS 13 level of less than 10%, a diagnosis of TTP is made. With ADAMTS 13 over 10-20%, the patient falls into the «grey zone» and a repeat enzyme test is required. If there are signs of fulminant multiple organ failure, especially in a patient with initial suspicion of APS, CAPS can be suspected. To confirm it, high titres of APA are required. In addition, TMA may cause: sepsis and various urgent obstetric conditions complicated by the development of DIC.

Tackling COVID-19 infection through complement-targeted immunotherapy.

The complement system is an ancient part of innate immunity sensing highly pathogenic coronaviruses by mannan‐binding lectin (MBL) resulting in lectin pathway activation and subsequent generation of the anaphylatoxins (ATs) C3a and C5a as important effector molecules. Complement deposition on endothelial cells and high blood C5a serum levels have been reported in COVID‐19 patients with severe illness, suggesting vigorous complement activation leading to systemic thrombotic microangiopathy (TMA). Complement regulator gene variants prevalent in African‐Americans have been associated with a higher risk for severe TMA and multi‐organ injury. Strikingly, severe acute respiratory syndrome Coronavirus 2 (SARS‐CoV‐2)‐infected African‐Americans suffer from high mortality. These findings allow us to apply our knowledge from other complement‐mediated diseases to COVID‐19 infection to better understand severe disease pathogenesis. Here, we discuss the multiple aspects of complement activation, regulation, crosstalk with other parts of the immune system, and the options to target complement in COVID‐19 patients to halt disease progression and death.Linked ArticlesThis article is part of a themed issue on Canonical and non‐canonical functions of the complement system in health and disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.14/issuetoc

Pembrolizumab-associated thrombotic microangiopathy in a patient with urothelial cancer: a case report and literature review

BackgroundPembrolizumab, a highly selective humanized monoclonal IgG4κ isotype antibody against PD-1, is one of the immune checkpoint inhibitors approved for treatment of various cancers. The most frequent immune-related adverse events include skin, gastrointestinal, and endocrine abnormalities. In rare cases, however, adverse events on the kidney do occur.Case presentationWe here report a case of acute kidney injury presenting thrombocytopenia and hemolytic anemia with the presence of schistocytes, which developed in a 68-year-old man with urothelial cancer, 7 months after initiation of pembrolizumab treatment (10 cycles) and 3 weeks after treatment cessation. The patient had previously undergone unilateral nephrectomy and prior treatment with combined gemcitabine and carboplatin regimen. Although corticosteroid, hemodialysis, and plasma exchange were initiated, the patient died within a few days of respiratory failure. Pathological examination at autopsy revealed multiple carcinomas including the lung, liver, and spine, together with the diagnosis of thrombotic microangiopathy by electron microscopy findings of the renal tissue. To our knowledge, this is the first report describing severe thrombotic microangiopathy in a patient possibly associated with pembrolizumab, leading to death.ConclusionPhysicians should be aware of this potential side effect in patients presenting acute kidney injury and thrombocytopenia.

P0097IDENTIFICATION OF TWO NOVELS SINGLE NUCLEOTIDE VARIANTS OF THE COMPLEMENT GENES IN A PATIENT WITH THE ASSOCIATION OF PREGNANCY ATYPICAL HEMOLYTIC UREMIC SYNDROME AND C3 GLOMERULOPATHY

Abstract Background and Aims Advances in the past 2 decades have shown atypical hemolytic uremic syndrome (aHUS) to be a disorder of the alternative pathway of complement. Most aHUS cases involve sequence variations in genes encoding complement proteins The term pregnancy associated aHUS (P-aHUS) refer to the thrombotic microangiopathy (TMA) that result from uncontrolled complement activation during pregnancy or the postpartum period. P-aHUS is a devastating systemic disease, with high maternal mortality and morbidity rates, in the pre-eculizumab era. The term ‘C3 glomerulopathy’ (C3GN) encompasses a heterogeneous spectrum of immune-mediated nephropathies that share a common pathological feature, glomerular deposition of C3. This entity may progress to advanced stages of chronic kidney disease and shares a common genetic risk factors with aHUS. Even more, some authors even suggest that C3GN and aHUS represent two forms of a disease spectrum with a common pathogenic principle. Here, we report this rare association and describe the family genetic variants that could cause it Method We describe the clinical and laboratoy data of a patient with the association of aHUS and C3 Glomerulopathy. A genetic study was performed and her available relatives were also screened for mutations/polymorphisms in aHUS-associated complement genes. After extracting gDNA from whole blood (Wizard Genomic DNA Purification Kit, Promega), PCR products of coding sequences and intronic flanking regions of complement genes were sequenced by ABI PRISM 310 Genetic Analyzer (Applied Biosystems). In silico analysis for pathogenicity was completed with Polyphen2-HDIV, PhyloP/Phastcons (MutationTaster), SIFT and PANTHER. All the participants provided informed written consent Results In 3/2012 a 27-year-old patient, with no family history, started his current illness one month after his first natural birth, with acute renal failure and microangiopathic hemolytic anemia, demonstrating a severe TMA in a renal biopsy. Laboratory results showed low C3 serum levels, but C4 were normal, haptoglobine was undetectably low, and all ADAMTS13 parameters were normal. Her urine tests showed also glomerular hematuria and proteinuria in the nephrotic range. She was treated with plasmapheresis and fresh frozen plasma with hematological improvement, but hemodialysis was required for more than 3 months. Despite partial recovery of renal function, six months later reappeared anemia and developed severe arterial hypertension, congestive heart failure and progressive renal insufficiency. Diagnosis of aHUS was made and start treatment with eculizumab with progressive recovery of renal function in the following months. Nevertheless the C3 serum levels persisted low and the proteinuria and hematuria did not change even after long term treatment with eculizumab. Retrospectively, her urynalisis before the pregnant showed proteinuria and hematuria, and a revision of a renal biopsy revealed the presence of dominant C3 deposits in the immunofluorescence, and electrondense deposits in the electronic microscopy, suggesting the diagnostic of C3GN. In a genetic study two novel single nucleotide variants were founded (CFH c.575G>A, p.C192Y (exon 5) (NM_000186), predicted to be pathogenic by 4 of 5 available pathogenicity prediction programs; and CFI c.1189G>T, p.V397L (exon 11) (NM_000204), predicted pathogenic by 0 of 6 available pathogenicity prediction programs). (Figure 1) Conclusion We present here the family genetic bases of a patient who developed a C3GN and a aHUS with a different response to treatment with eculizumab. In this case we identified two novel genetic variants in the CFH and CFI genes in a patient with aHUS, who inherited one variant from each parent. Although the CFI variant is predicted to be benign, the CFH variant is predicted to be damaging. It is located in exon 5, which encodes a portion of the factor H protein implicated in binding to C3b

Isolated thrombotic microangiopathy of the small intestine in a patient with atypical hemolytic uremic syndrome \u2013 a case report

BackgroundAtypical hemolytic uremic syndrome (aHUS) is a rare disease characterized by systemic thrombotic microangiopathy (TMA) reflected by hemolysis, anemia, thrombocytopenia and systemic organ injury. The optimal management of aHUS-patients when undergoing kidney transplantation to prevent recurrence in the allograft is eculizumab, an approved recombinant antibody targeting human complement component C5.Case presentationA 39 year-old woman presented with severe abdominal pain, diarrhea and emesis for 3 days. In her past medical history she had experienced an episode of aHUS leading to end stage renal disease (ESRD) in 2007 and a genetic workup revealed a heterozygous mutation in the membrane cofactor protein gene. In 2014 she underwent cadaveric kidney transplantation. Four years later she had to go back on hemodialysis due to allograft failure following a severe systemic cytomegalovirus infection resulting in transplant failure. At presentation she still received calcineurin-inhibitor therapy and reported subfebrile temperatures and pain projecting over the transplant prior to the current symptoms. A contrast enhanced CT-scan of the abdomen revealed inflammatory wall thickening of the small intestine. Diagnostic endoscopy discovered fresh blood in the small intestine without a clear source of bleeding. Histopathology of the small intestine biopsies showed severe thrombotic microangiopathy. Of note, the patient persistently had no signs of systemic hemolysis. Since the TMA of the small intestine was most likely due to aHUS, eculizumab treatment was initiated which abolished the symptoms.ConclusionHere we report a patient with thrombotic microangiopathy with predominant manifestation in a single organ, the small intestine, due to aHUS with absence of systemic signs and symptoms. aHUS patients usually require a secondary trigger for the disease to manifest. In this case, the trigger may be attributed to the dysfunctional renal transplant, which was subsequently explanted. Histology of the explanted kidney showed severe inflammation due to purulent nephritis and signs of cellular rejection. After nephrectomy, we continued eculizumab therapy until the patient completely recovered. No signs of TMA recurred after discontinuation of eculizumab, further supporting the concept of the renal transplant as the main trigger of TMA of the small intestine in our patient.

Peri- and Post-operative Evaluation and Management of Atypical Hemolytic Uremic Syndrome (aHUS) in Kidney Transplantation.

Atypical hemolytic uremic syndrome (aHUS) is a severe thrombotic microangiopathy characterized by over-activation of the alternative complement pathway. The etiology of the dysregulated complement system is commonly a genetic variant in one or more complement proteins as identified in ∼ 60%-70% patients. The risk of recurrence after a kidney transplantation is high and depends on the underlying complement abnormality. For a long time, kidney transplantation was contraindicated in these patients because of the high rate of recurrence and subsequent allograft loss. Over the past decade, advancements in the understanding of etiopathogenesis of aHUS and approval of the anti-complement drug, eculizumab, have allowed for successful kidney transplantation in these patients. All patients with ESRD due to aHUS should undergo screening for complement genetic variants. Patients in whom a genetic variant is not identified or in whom a genetic variant of uncertain significance is identified should undergo further testing to determine etiology of disease. This review aims to shed light on the diagnostic and therapeutic considerations in patients with aHUS preceding and following kidney transplantation.

Combination of plasma exchange and haemofiltration for treating thrombotic microangiopathy in children.

ObjectiveTo investigate the therapeutic effects of a combination of plasma exchange (PE) and haemofiltration (HF) for the treatment for paediatric patients with severe thrombotic microangiopathy (TMA).MethodsThis retrospective study analysed data from paediatric patients who were diagnosed with severe TMA and managed with either supportive therapy and additional PE and HF (PE + HF group) or supportive therapy alone (control group). Demographic and clinical characteristics, haemopurification and blood parameters and survival of the patients were compared between the two groups.ResultsThis study enrolled 32 patients: PE + HF group (n = 15) and control group (n = 17). There were no significant differences between the two groups at baseline, including specific features for differentiating the two categories of TMA. The median time between onset and recovery, defined by the markers of platelet count, lactate dehydrogenase, blood urine nitrogen and hospital stay, were all significantly longer in the control group compared with the PE + HF group. Kaplan–Meier curve analysis demonstrated that the cumulative survival rate was significantly higher in the PE + HF group compared with the control group.ConclusionThe combination of PE and HF could be considered as one of the treatment choices for TMA.

Results from an Expanded Access Program of Anti-CD3/CD7 Immunotoxin Combination (T-Guard®) for the Treatment of Steroid-Refractory Acute Gvhd

Background More effective therapies for treating steroid-refractory acute GVHD (SR-aGVHD) are urgently needed. In our recent phase I/II study, we showed that anti-CD3/anti-CD7 immunotoxin (IT) therapy T-Guard was both safe and well tolerated, and yielded both a high rate of CR and high 6-month OS in high-risk patients (Groth et al. BBMT 2019). Following this study, patients with SR-aGVHD were offered T-Guard via an expanded access treatment program (EAP). Objectives We evaluated patients' outcome after receiving T-Guard for SR-aGVHD. In addition, we examined the relationship between plasma citrulline levels (a biomarker of enterocyte mass) and the response to T-Guard in a subset of patients with SR-aGVHD of the gut, combining 16 patients from the phase I/II trial and 9 patients in the EAP group. Methods An EAP was started after completion of the phase I/II trial. This program was approved by the local ethics committee and the Health and Youth Care Inspectorate of the Dutch government. Adult patients with grade II-IV SR-aGVHD were eligible to receive T-Guard as their second- or third-line treatment for aGVHD. Patients with an uncontrolled infection, signs of moderate-severe chronic GVHD, and/or severe renal impairment were not eligible to receive T-Guard. Eligible patients received four 4-hour i.v. infusions of 4 mg/m2 T-Guard delivered at 48-hour intervals. In addition, plasma citrulline levels were measured at baseline and every 7 days after the start of T-Guard therapy using HPLC with mass spectrometry. A plasma citrulline level <10 µmol/L was considered to indicate severe GI-GVHD. Results From Jan. 2017 through Dec. 2018, 12 patients (8 male, 4 female; median age: 54 yr, range: 20-70 yr) who had received an allogeneic stem cell transplantation for myeloid or lymphoid malignancy were treated with T-Guard. T-Guard was given as the second-line therapy to 10 patients; the remaining 2 patients received T-Guard as the third-line therapy after receiving ruxolitinib (N=1) or cyclosporin-UVB (N=1). The median time between aGVHD onset and the start of T-Guard therapy was 7 days (range: 3-55 days). SR-aGVHD was classified as grade II, III, or IV in 1, 7, and 4 patients, respectively. Nine patients (75%) had GI involvement, and the skin and liver were involved in 6 and 2 cases, respectively. All 12 patients were classified as high-risk in accordance with MacMillan et al. (BJH 2012), and the median albumin level at baseline was 23 g/L (range: 13-32 g/L). By treatment day 28, 9 patients (75%) had achieved a clinical response, with 5 achieving complete remission. After a median follow-up of 16 months, 7 patients were alive; the 6-month and 1-year OS rate was 75% and 58%, respectively, which was significantly higher than historical controls; Figure 1. The cause of death in the other five patients was refractory aGVHD (N=3), relapse AML (N=1), and GVHD after undergoing a second stem cell transplantation for relapse AML (N=1). No significant infusion-related reactions were recorded. As expected, the overall rate of infection was high, but was comparable to other cohorts; 1 and 2 patients developed an EBV or CMV infection, respectively, but these were manageable. The most common potentially treatment-related adverse events were transient worsening of hypoalbuminemia and thrombocytopenia. One patient developed grade 2 vascular leak syndrome, but this was easily managed. One patient developed severe thrombotic microangiopathy with renal insufficiency, but several contributing factors other than the use of T-Guard were present in this patient, including calcineurin toxicity, severe GI-GVHD, and CMV disease. Our preliminary analysis of citrulline levels in 16 patients with GI-GVHD showed that mean baseline levels were extremely low (4.3 µmol/L; range: 2.9-17.9 µmol/L); 28 days after the start of T-guard, citrulline levels had increased significantly in the 9 patients who achieved complete remission; Figure 2. Conclusion Consistent with our recent phase I/II trial, our expanded access program in which 12 patients with high-risk SR-aGVHD received T-guard confirms that this treatment is safe and significantly improves patient outcome. A multicenter phase III study is planned to start in 2019 (BMT-CTN 1802). Disclosures Hooren: Xenikos BV: Employment. van Oosterhout:Xenikos BV: Employment.