Anti-factor H antibody-positive C3 glomerulonephritis secondary to poststreptococcal acute glomerulonephritis with diabetic nephropathy.

Poststreptococcal acute kidney glomerulonephritis (PSAGN) has been seen in adults in recent years, especially in patients with type 2 diabetes mellitus, and the renal prognosis has not always been good. There have been cases of PSAGN in which complete remission was not achieved and hematuria and proteinuria persisted, leading to end-stage renal disease. Previous reports showed that the patients subjected to PSAGN have an underlying defect in regulating the alternative pathway of complement, and they identified that antibodies to the C3 convertase, C3 nephritic factors (C3NeF), are involved. C3NeF stabilizes C3 convertase, sustains C3 activation, and causes C3 glomerulonephritis (C3GN). On the other hand, factor H is a glycoprotein that suppresses the overactivation of the alternative pathway by decaying the C3 convertase. Anti-factor H (aFH) antibodies interfere with factor H and cause the same activation of the alternative pathway as C3NeF. However, a limited number of reports describe the clinical course of C3GN with aFH antibodies. We encountered a 49-year-old Japanese man with type 2 diabetes mellitus. He was referred to our hospital because of his elevated serum creatinine, proteinuria, hematuria, and developed edema on both legs. He was diagnosed as PSAGN at the first kidney biopsy, and his renal function improved and edema and hematuria disappeared, but proteinuria persisted after 5 months. He was diagnosed as C3GN at the second kidney biopsy. In our case, no C3NeF was detected. However, a high titer of aFH antibodies was detected in stored serum from the initial presentation, providing a unified diagnosis of aFH antibody-positive C3GN secondary to PSAGN. He progressed to end-stage renal disease (ESRD) and hemodialysis was started. The persistence of high levels of aFH autoantibodies may have caused C3GN secondary to PSAGN due to activating the alternative complement pathway, which eventually worsened the nephropathy and led to ESRD.

Immunoelectron microscopy findings in a patient with C3 glomerulonephritis.

We performed a kidney biopsy in a 36-year-old man to evaluate microscopic hematuria and proteinuria. Light microscopy showed increased mesangial matrix and partial swelling of the glomerular basement membrane (GBM), and immunofluorescence showed positive staining only for C3. Immunoelectron microscopy showed that gold particle-labeled C3 was localized in the electron-dense and moderately electron-dense deposits shown by electron microscopy in the mesangium, the thickened GBM near the paramesangium, and the thickened distal portion of the GBM but was not localized in the non-thickened GBM. Gold-labeled immunoglobulin G, κ, and λ were not seen. C3 glomerulonephritis was more evident in gold-labeled electron microscopy, which further clarified the localization of C3 deposition.

Immunohistochemistry May Not Replace Immunofluorescence in Paraffin-embedded Tissue for Detecting Masked Monoclonal Immunoglobulin Deposits.

An 84-year-old man developed a membranoproliferative glomerulonephritis pattern of injury, and the most likely cause detected during a workup was monoclonal IgG-λ in the urine and serum. Predominant IgG and λ light chain deposition was confirmed only by immunofluorescence using formalin-fixed, paraffin-embedded tissue and not by immunohistochemistry. A smaller and non-linear dynamic range of immunohistochemistry makes it less quantitative than immunofluorescence staining and may explain why immunohistochemistry failed to detect the light chain restriction. This case suggests that immunohistochemistry may not serve as a substitute for immunofluorescence on formalin-fixed, paraffin-embedded tissue in detecting masked monoclonal immunoglobulin deposits, although further research is warranted.

Anti-Factor H Antibodies in Egyptian Children with Hemolytic Uremic Syndrome.

BACKGROUND: Atypical hemolytic uremic syndrome (aHUS) is an important cause of acute kidney injury in children. It is primarily caused by dysregulation of the complement alternative pathway due to genetic mutations, mainly in complement factor H genes, or due to anti-factor H autoantibodies (anti-FH), leading to uncontrolled overactivation of the complement system. Early diagnosis and treatment of autoimmune HUS (AI-HUS) is essential and leads to a favorable outcome. METHODS: Fifty pediatric HUS patients and 50 age- and sex-matched controls were included in the study. Patients were subjected to full history taking, clinical examination, and laboratory testing. All candidates were subjected to an assessment of anti-FH in serum by a homemade enzyme-linked immunosorbent assay technique. RESULTS: A high frequency of serum anti-FH was detected in our aHUS patients. The disease onset of AI-HUS was mainly observed in March and April, with significantly higher rates in school-aged males. All patients who started immunosuppressives early together with plasmapheresis upon detection of their anti-FH had complete renal function recovery. CONCLUSION: The high frequency of AI-HUS revealed in Egyptian HUS children in our study highlights the importance of implementing anti-FH testing in Egypt to provide early recognition for immediate proper management, including early immunosuppressive therapy, and hence improving patient outcomes.

Systematic Review of Genotype-Phenotype Correlations in Frasier Syndrome.

INTRODUCTION: Frasier syndrome (FS) is a rare inherited kidney disease caused by intron 9 splicing variants of WT1. For wild-type WT1, 2 active splice donor sites in intron 9 cause a mixture of 2 essential transcripts (with or without lysine-threonine-serine [+/KTS or -KTS]), and imbalance of the +KTS/-KTS ratio results in the development of FS. To date, 6 causative intron 9 variants have been identified; however, detailed transcript analysis has not yet been conducted and the genotype-phenotype correlation also remains to be elucidated. METHODS: We conducted an in vitro minigene splicing assay for 6 reported causative variants and in vivo RNA sequencing to determine the +KTS/-KTS ratio using patients' samples. We also performed a systematic review of reported FS cases with a description of the renal phenotype. RESULTS: The in vitro assay revealed that although all mutant alleles produced -KTS transcripts only, the wild-type allele produced both +KTS and -KTS transcripts at a 1:1 ratio. In vivo RNA sequencing showed that patients' samples with all heterozygous variants produced similar ratios of +KTS to -KTS (1:3.2-1:3.5) and wild-type kidney showed almost a 1:1 ratio (1:0.85). A systematic review of 126 cases clarified that the median age of developing ESKD was 16 years in all FS patients, and there were no statistically significant differences between the genotypes or sex chromosome karyotypes in terms of the renal survival period. CONCLUSION: Our study suggested no differences in splicing pattern or renal survival period among reported intron 9 variants causative of FS.

Mean of creatinine clearance and urea clearance examined over 1 h estimates glomerular filtration rate accurately and precisely in children.

AIM: Accurate and precise estimation of glomerular filtration rate (GFR) is essential in kidney disease. We evaluated the usefulness of the mean of creatinine clearance (CCr ) and urea clearance (CUN ) examined over a 1-h urine collection period (1-h (CCr + CUN )/2) in a retrospective, cross-sectional study across two centres, as a relatively simple method for estimating GFR in children. METHODS: Children aged ≤18 years who underwent inulin clearance (CIn ) tests were eligible. Two clearance values were obtained during a 2-h test consisting of two periods of 1 h each. The mean clearance in two periods was defined as 1-h clearance. 1-h (CCr + CUN )/2, 1-h CCr , 1-h CUN and GFR estimated by Cr-based and cystatin C (CysC)-based formulas for Japanese children were compared with CIn . Bland-Altman plots were used to evaluate correlations. The primary outcome measure was the correlation between 1-h (CCr + CUN )/2 and CIn . RESULTS: Fifty-three children were analysed. Their median age was 10.9 (interquartile range [IQR] 5.3-14.2) years, and median CIn and 1-h (CCr + CUN )/2 were 77.0 (IQR: 51.5-95.1) and 81.0 (IQR: 64.1-97.7) ml/min/1.73 m2 , respectively. Percentage difference of CIn and 1-h (CCr + CUN )/2 in the Bland-Altman plot was -11.2% (95% confidence interval - 15.3% - -7.1%), with 95% lower and upper limits of agreement of -40.3% and 18.0%, respectively. Thus, 1-h (CCr + CUN )/2 was 1.12 times CIn . CONCLUSION: 1 h (CCr + CUN )/2 was almost concordant with CIn . 1-h (CCr + CUN )/2 can estimate GFR accurately and precisely, making it a simple and speedy test for use in clinical practice.

Association between plasma complement factor H concentration and clinical outcomes in patients with sepsis.

AIM: The complement system is important for defending against pathogens, however, excessive complement activation is associated with a poor prognosis and organ dysfunction in sepsis. Complement factor H (CFH) acts to prevent excessive complement activation and damage to the self through the regulation of the complement alternative pathway. We investigated the association between plasma CFH levels on admission to the intensive care unit (ICU) and 90-day mortality, severity scores, and organ dysfunction in patients with sepsis. METHODS: We assessed the relationship between the plasma CFH on admission to the ICU and 90-day mortality, severity scores such as the Acute Physiology and Chronic Health Evaluation II score, Sequential Organ Failure Assessment score, and Simplified Acute Physiology Score 2, and organ dysfunction. RESULTS: This analysis included 62 patients. The plasma CFH levels were significantly lower in 90-day non-survivors than in survivors (70.0 µg/mL [interquartile range, 51.2-97.6] versus 104.8 µg/mL [interquartile range, 66.8-124.2]; P = 0.006) . The plasma CFH levels were associated with 90-day mortality (odds ratio 0.977; 95% confidence interval, 0.957-0.994; P = 0.01). The plasma CFH levels were negatively correlated with severity scores. The Sequential Organ Failure Assessment scores for the coagulation and neurological components were negatively correlated with the CFH concentration. CONCLUSION: Lower plasma levels of CFH were associated with increased severity and mortality in patients with sepsis on admission to the ICU and were correlated with central nervous system dysfunction and coagulopathy.

Uptake of further investigations following universal urinary screening among elementary and junior high school students in Shiga Prefecture, Japan: A retrospective cohort study.

AIM: This study aimed to investigate the current progression status from screening phase to further investigation phase in the Japanese school urine mass screening (SUS) project. METHODS: This retrospective cohort study on the SUS project across the Shiga Prefecture during 2012 to 2017 analysed data from school life instruction sheets, which are principal documents in the SUS project, regarding urinalysis, attendance at follow-up and diagnoses. RESULTS: Between the years 2012 to 2017, a median of 107 out of 83 749 elementary school students (aged 6-11 years) and 215 out of 42 870 junior high students (aged 12-14 years) had urine abnormalities identified for the first time in the SUS project. Among those with urine abnormalities, a mean of 4.2% of elementary school and 1.8% of junior high school students, respectively, were diagnosed with suspected glomerulonephritis for the first time. Overall, 5.9% (95% confidence interval [CI] 4.1, 7.7) and 23.6% (95% CI 21.3, 25.9) of proteinuria-positive elementary and junior high school students, respectively, did not undergo further investigations. The probability of a student undergoing further investigations was not affected by the local availability of medical care benefits. CONCLUSION: In the current SUS project, screening frequently does not lead to further investigation, especially among junior high school students. To maintain the integrity of the SUS project and to prevent the progression of renal disease in young students, efforts including elucidation of barriers to further investigations should be made to reduce the proportions of students not undergoing further investigations for abnormal urinalysis findings.

Eculizumab for Severe Thrombotic Microangiopathy Secondary to Surgical Invasive Stress and Bleeding.

Atypical hemolytic uremic syndrome (aHUS) is an extremely rare condition caused by an excessive activation of the complement pathway based on genetic or acquired dysfunctions in complement regulation, leading to thrombotic microangiopathy (TMA). A complement-amplifying condition (CAC) can trigger aHUS occurrence along with complement abnormality. We herein report a case of severe TMA after laparoscopic myomectomy in a healthy woman. This case was eventually diagnosed as complement-mediated TMA secondary to surgical invasive stress as a CAC, with no definitive diagnosis of aHUS despite a genetic test. The patient fully recovered after several eculizumab administrations.

Functional splicing analysis in an infantile case of atypical hemolytic uremic syndrome caused by digenic mutations in C3 and MCP genes.

Pathogenic variants in specific complement-related genes lead to atypical hemolytic uremic syndrome (aHUS). Some reports have indicated that patients with digenic variants in these genes might present severer phenotypes. Upon detecting novel intronic variants, transcriptional analysis is necessary to prove pathogenicity; however, when intronic variants are located in intron 1 and, as a result, no transcript is produced, no appropriate method had been established to reveal the pathogenicity. Recently, the minigene assay was used to assess the pathogenicity of intronic variants. Here, we report an infantile case of aHUS caused by digenic mutations in two different complement-related genes, C3 and MCP. Targeted sequencing detected a known variant in C3 and a novel variant in the intron 1 splicing donor site of MCP. To assess the pathogenicity of this intronic variant, we conducted functional splicing assay using a minigene construct and quantitative PCR analysis of the MCP transcript, revealing the pathogenicity of the intronic variant. In conclusion, the minigene assay revealed the pathogenicity of the intron 1 splicing donor site variant for the first time. This case showed a severe phenotype of infantile-onset aHUS associated with digenic variants in two complement-related genes.

Clinical features in a series of 258 Japanese pediatric patients with thrombotic microangiopathy.

BACKGROUND: Thrombotic microangiopathy (TMA) includes hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP). This study examined the epidemiological characteristics of pediatric patients with TMA classified according to etiology. METHODS: The survey evaluated 258 Japanese pediatric patients diagnosed with TMA between 2012 and 2015. RESULTS: The primary diseases responsible for TMA were categorized as TTP (15 cases), Shiga toxin-producing Escherichia coli-associated HUS (STEC-HUS) (166 cases), atypical HUS (aHUS) (40 cases), and secondary TMA (27 cases). The remaining 10 cases were unable to be classified to one of the four categories of the primary disease. Renal replacement therapy was required in the acute phase in 103 patients with TMA, including 65 with STEC-HUS, 22 with aHUS, two with TTP, 10 with secondary TMA, and four unclassified cases. The last observational findings were normal renal function in 95 patients and chronic kidney disease (CKD) stage 1 in 62. For 31 patients, chronic renal insufficiency (CKD stage 2-5) persisted, including four patients with end-stage kidney disease (CKD stage 5). Seventeen patients suffered recurrence of TMA, and eight patients died. CONCLUSION: This study clarified differences in the relative proportions of primary diseases between patients from Japan and North America and Europe. The difference may be attributable to the lower estimated incidence of STEC-HUS in Japan.

A preliminary study of gut dysbiosis in children with food allergy.

Gut microbiota of food allergic children was analyzed by high throughput 16S rRNA gene sequencing. Signs of gut dysbiosis, which is likely associated with gut inflammation, was observed in children with food allergies. For example, decreased abundance of genus Akkermansia but increased abundance of Veillonella was found in children with food allergy in comparison with healthy control children.

A preliminary investigation on the relationship between gut microbiota and gene expressions in peripheral mononuclear cells of infants with autism spectrum disorders.

Fecal and blood samples of infants with autism spectrum disorders (ASD) and healthy infants were analyzed to investigate the association of altered gut microbiota and ASD development. 16S rRNA gene-based sequencing found that, unlike those of healthy infants, feces of ASD infants had significantly higher and lower abundance of genera Faecalibacterium and Blautia, respectively. Moreover, DNA microarray analysis of peripheral blood mononuclear cells (PBMC) detected more highly than low expressed genes in ASD infants than in healthy infants. Gene Ontology analysis revealed that differentially expressed genes between ASD and healthy infants were involved in interferon (IFN)-γ and type-I IFN signaling pathways. Finally, strong positive correlations between expression of IFN signaling-associated genes in PBMC and fecal abundance of Faecalibacterium were found. Our results strongly suggested that altered gut microbiota in infants resulted from ASD development and was associated with systemic immunity dysregulation, especially chronic inflammation.

Clinical guides for atypical hemolytic uremic syndrome in Japan.

Atypical hemolytic uremic syndrome (aHUS) is a rare disease characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. In 2013, we developed diagnostic criteria to enable early diagnosis and timely initiation of appropriate treatment for aHUS. Recent clinical and molecular findings have resulted in several proposed classifications and definitions of thrombotic microangiopathy and aHUS. Based on recent advances in this field and the emerging international consensus to exclude secondary TMAs from the definition of aHUS, we have redefined aHUS and proposed diagnostic algorithms, differential diagnosis, and therapeutic strategies for aHUS.

Clinical guides for atypical hemolytic uremic syndrome in Japan.

Atypical hemolytic uremic syndrome (aHUS) is a rare disease characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. In 2013, we developed diagnostic criteria to enable early diagnosis and timely initiation of appropriate treatment for aHUS. Recent clinical and molecular findings have resulted in several proposed classifications and definitions of thrombotic microangiopathy and aHUS. Based on recent advances in this field and the emerging international consensus to exclude secondary TMAs from the definition of aHUS, we have redefined aHUS and proposed diagnostic algorithms, differential diagnosis, and therapeutic strategies for aHUS.

Escherichia coli O121:H19 infection identified on microagglutination assay and PCR.

Non-O157 Shiga toxin-producing Escherichia coli (STEC) strains are increasingly recognized as foodborne pathogens that trigger hemolytic uremic syndrome (HUS). The detection and isolation of these strains is important, but distinguishing their bacteriological profiles is difficult. A 2-year-old girl developed HUS with mild renal involvement 22 days after consuming barbecued meat. Clinical and laboratory findings gradually improved without specific treatment. Because neither enterohemorrhagic E. coli (EHEC) nor Shiga toxins were detected in stool cultures in a clinical laboratory and the patient tested negative for circulating antibodies to O157 lipopolysaccharide, the case was initially diagnosed as probable atypical HUS. Subsequent serodiagnostic microagglutination assay and polymerase chain reaction-based molecular testing, however, indicated the presence of the EHEC O121:H19 strain with stx2. Thus, to correctly diagnose and treat HUS, a system for detecting non-O157 STEC in a clinical setting is urgently needed.

Diagnostic criteria for atypical hemolytic uremic syndrome proposed by the Joint Committee of the Japanese Society of Nephrology and the Japan Pediatric Society.

Atypical hemolytic uremic syndrome (aHUS) is rare and comprises the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Recently, abnormalities in the mechanisms underlying complement regulation have been focused upon as causes of aHUS. The prognosis for patients who present with aHUS is very poor, with the first aHUS attack being associated with a mortality rate of approximately 25%, and with approximately 50% of cases resulting in end-stage renal disease requiring dialysis. If treatment is delayed, there is a high risk of this syndrome progressing to renal failure. Therefore, we have developed diagnostic criteria for aHUS to enable its early diagnosis and to facilitate the timely initiation of appropriate treatment. We hope these diagnostic criteria will be disseminated to as many clinicians as possible and that they will be used widely.