Protocol for the nationwide registry of patients with polycystic kidney disease: japanese national registry of PKD (JRP).

BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD) and autosomal recessive polycystic kidney disease (ARPKD) are major genetic polycystic kidney diseases that can progress to end-stage kidney disease (ESKD). Longitudinal data on the clinical characteristics associated with clinical outcomes in polycystic kidney disease (PKD), including the development of ESKD and cardiovascular disease (CVD) are lacking in Japan. To address this unmet need the authors are establishing a novel, web-based, Nationwide Cohort Registry Study-the Japanese Registry of PKD (JRP). METHODS: The JRP is a prospective cohort study for ADPKD (aim to recruit n = 1000 patients), and both a retrospective and prospective study for ARPKD (aim to recruit n = 100). In the prospective registry, patients will be followed-up for 10 years every 6 months and 12 months for patients with ADPKD and ARPKD, respectively. Data collection will be recorded on Research Electronic Data Capture (REDCap) starting on April 1, 2024, with recruitment ending on March 31, 2029. (jRCT 1030230618). RESULTS: Data to be collected include: baseline data, demographics, diagnostic and genetic information, radiological and laboratory findings, and therapeutic interventions. During follow-up, clinical events such as development of ESKD, hospitalization, occurrence of extra kidney complications including CVD events, and death will be recorded, as well as patient-reported health-related quality of life for patients with ADPKD. CONCLUSIONS: The JRP is the first nationwide registry study for patients with ADPKD and ARPKD in Japan, providing researchers with opportunities to advance knowledge and treatments for ADPKD and ARPKD, and to inform disease management and future clinical practice.

Genetic Analysis of Severe Polycystic Liver Disease in Japan.

BACKGROUND: Polycystic liver disease (PLD) is present in most patients with autosomal dominant polycystic kidney disease (ADPKD). PLD can alternatively be found with few, if any, kidney cysts as a diagnosis of isolated polycystic liver disease (ADPLD). Several genes are identified as causative for this spectrum of phenotypes, however, the relative incidence of genetic etiologies amongst patients with severe PLD is unknown. METHODS: Patients with ADPKD or ADPLD having severe PLD defined as height-adjusted total liver volume (hTLV) over 1,800mL/m were recruited. Subsequent clinical care was followed. Genetic analysis was performed using whole exome sequencing. RESULT: We enrolled and sequenced 49 patients (38 females, 11 males). Pathogenic or suspected pathogenic variants in polycystic disease genes were found in 44 out of 49 patients (90%). The disease gene was PKD1 in 20/44 (45%), PKD2 in 15/44 (34%), PRKCSH in 5/44 (11%), GANAB in 2/44 (5%), SEC63 in 1/44 (2%), and ALG8 in 1/44 (2%). The median hTLV was no different between genetically-defined ADPKD and ADPLD groups (4431 (range 1817-9148) versus 3437 (range 1860-8211) mL, p=0.77), whereas height-adjusted kidney volume (hTKV) was larger as expected in ADPKD than ADPLD (607 (range 190-2842) versus 179 (range 138-234) mL/m, p<0.01). Of the clinically-defined ADPKD cases, 20/38 (53%) were PKD1, 15/38 (39%) were PKD2, and 3 (8%) remain genetically unsolved. Among patients with a pathogenic PKD1 or PKD2 variant, we found three cases with a liver-dominant ADPKD (severe PLD with hTKV <250mL/m). CONCLUSION: ADPLD-related genes represent 20% of severe PLD patients in our cohort. Of those enrolled with ADPKD, we observed a higher frequency of PKD2 carriers than in any previously reported ADPKD cohorts. While there was no significant difference in the hTLV between PKD1 versus PKD2 patients in this cohort, our data suggests that enrollment on the basis of severe PLD may enrich for PKD2 patients.

CFAP47 is a novel causative gene implicated in X-linked polycystic kidney disease.

Autosomal dominant polycystic kidney disease (ADPKD) is a well-described condition in which ~80% of cases have a genetic explanation, while the genetic basis of sporadic cystic kidney disease in adults remains unclear in ~30% of cases. This study aimed to identify novel genes associated with polycystic kidney disease (PKD) in patients with sporadic cystic kidney disease in which a clear genetic change was not identified in established genes. A next-generation sequencing panel analyzed known genes related to renal cysts in 118 sporadic cases, followed by whole-genome sequencing on 47 unrelated individuals without identified candidate variants. Three male patients were found to have rare missense variants in the X-linked gene Cilia And Flagella Associated Protein 47 (CFAP47). CFAP47 was expressed in primary cilia of human renal tubules, and knockout mice exhibited vacuolation of tubular cells and tubular dilation, providing evidence that CFAP47 is a causative gene involved in cyst formation. This discovery of CFAP47 as a newly identified gene associated with PKD, displaying X-linked inheritance, emphasizes the need for further cases to understand the role of CFAP47 in PKD.

De novo posttransplant membranous nephropathy after COVID-19 vaccination 9 years after renal transplantation in a patient with polycystic kidney disease.

A 63-year-old man with polycystic kidney disease underwent kidney transplantation from his wife. Nine years later, after the first and second doses of the COVID-19 vaccination, he developed proteinuria, hematuria, and elevated C-reactive protein. Kidney biopsy 7 months after the initial appearance of proteinuria showed immunoglobulin (Ig)-G granular stain, predominantly IgG1, and spike formation in the glomerular basement membrane. Electron microscopy revealed mainly subepithelial deposits, which corresponds to membranous nephropathy (MN) stage 3 of the Ehrenreich-Churg classification indicating chronic disease, but it also showed electron-dense deposits and endothelial damage. Because a kidney biopsy was performed 1 h after renal transplantation and a biopsy of the patient's native kidney showed intact glomeruli, atypical de novo posttransplant membranous nephropathy (MN) was diagnosed, and a close relationship with COVID-19 vaccination was assumed. Clinicians should consider the involvement of COVID-19 vaccination in de novo posttransplant MN with unclear pathogenesis.

Is Podocytopathy Associated with Gross Hematuria after COVID-19 Vaccination in Patients with Immunoglobulin A Nephropathy?

We experienced three cases of a fever and subsequent severe, prolonged gross hematuria after COVID-19 vaccination. A kidney biopsy revealed immunoglobulin A (IgA) nephropathy, and electron microscopy showed two types of podocytopathy (podocyte damage): loss of foot processes from the glomerular basement membrane and foot process effacement. Mesangial interposition was also present in cases 1 and 3 but not in case 2. Podocytopathy is known to be a cause of proteinuria; however, the reactions to COVID-19 vaccination described here suggest that it may also be related to hematuria in IgA nephropathy.

Trajectory of GFR Decline and Fluctuation in Albuminuria Leading to End-Stage Kidney Disease in Patients With Biopsy-Confirmed Diabetic Kidney Disease.

Introduction: Data on longitudinal trajectory of kidney function decline and fluctuation in albuminuria leading to end-stage kidney disease (ESKD) is sparse in patients with type 2 diabetes. Methods: Using data from an observational study of patients with type 2 diabetes and biopsy-confirmed diabetic kidney disease (DKD), generalized additive mixed models (GAMMs) were performed to quantify patterns of longitudinal trajectory of estimated glomerular filtration rate (eGFR) decline to ESKD associated with repeated measures of urine albumin-to-creatinine ratio (ACR). Results: Over a median follow-up period of 3.3 years, 155 of 319 patients progressed to ESKD. Among these patients, 91.6% exhibited a curvilinear pattern in their eGFR trajectory. The median coefficient of variation for ACR, representing the variability in ACR measurements, was 48.9 (interquartile range: 36.9, 68.2). The median compound annual growth rate (CAGR) for ACR, reflecting the variation in ACR progression over time, was 43.6% (interquartile range: 0.0, 102.5); and 84.5% of patients developed nephrotic-range albuminuria, with a majority remaining nephrotic and subsequently progressing to ESKD. There was a positive association between the instantaneous speed of eGFR decline and ACR. Conclusion: The observed curvilinear pattern in eGFR trajectory, high variability in ACR progression over time, and positive correlation between the speed of eGFR decline and ACR highlight the complex dynamics of disease progression and emphasize close monitoring of ACR fluctuation over time in patients with DKD.

Autopsy of a 45-year-old Man with Liver Failure Due to Polycystic Liver Disease.

A 37-year-old man with autosomal polycystic kidney disease (ADPKD) was admitted to our hospital with a liver volume of 8,000 cm3. Hepatic arterial embolization was performed using a microcoil but was ineffective. Eight years later, the hepatomegaly progressed to liver failure and death. At autopsy, the liver weighed 21.5 kg, and the entire liver had been replaced by cysts; in the few remaining areas of liver parenchyma, microscopic, small cysts of various sizes and fibrosis were evident, with only a few normal hepatocytes observed. Hepatic arterial branches developed; however, the portal vein could not be observed.

Immunoglobulin G4-related Dacryoadenitis Successfully Treated with Baricitinib.

A 48-year-old woman visited our hospital because of bilateral lacrimal gland enlargement. Her serum immunoglobulin G4 (IgG4) level was high, and positron emission tomography-computed tomography showed significant positive findings in the bilateral lacrimal gland. A biopsy revealed a considerable increase in IgG4/CD138, leading to a diagnosis of IgG4-related dacryoadenitis. The disease did not respond to steroid therapy, so treatment was started with baricitinib because of exacerbation of the original atopic dermatitis and dacryoadenitis after the second dose of the coronavirus disease 2019 (COVID-19) vaccine. Baricitinib was effective for resolving both dermatitis and dacryoadenitis, and steroids were able to be discontinued. The IgG4 level also improved.

Histologically Proven Recurrent Synovitis after Nivolumab Treatment.

A 58-year-old woman with rheumatoid arthritis was diagnosed with methotrexate-associated Hodgkin lymphoma. After receiving several chemotherapy regimens, she started nivolumab treatment. Two weeks later, she was hospitalized with worsening finger, wrist, and elbow joint pain. A synovial biopsy of the wrist joint showed villous synovial proliferation and linear infiltration of CD68-/CD3-positive T cells (with more CD8 than CD4 T cells) but no CD20-positive B cells or CD138-positive macrophages. These findings corresponded to synovitis associated with immune-related adverse events, which are induced mainly by T cells and are different from typical rheumatoid arthritis (RA), in which B cells play a central role.

A Case of Autosomal Dominant Polycystic Kidney Disease With Resolution of Massive Pericardial Effusion After Renal Transcatheter Artery Embolization.

A 68-year-old woman being treated with hemodialysis for autosomal dominant polycystic kidney disease was admitted for progressive dyspnea over 6 months. On chest radiography, her cardiothoracic ratio had increased from 52.2% 6 months prior, to 71%, and echocardiography revealed diffuse pericardial effusion and right ventricular diastolic insufficiency. A resultant pericardial tamponade was thought to be the cause of the patient's dyspnea, and therefore a pericardiocentesis was performed, with a total of 2,000mL of fluid removed. However, 21 days later the same amount of pericardial fluid had reaccumulated. The second pericardiocentesis was performed, followed by transcatheter renal artery embolization (TAE). The kidneys, which were hard on palpation before TAE, softened immediately after TAE. After resolution of the pericardial effusion was confirmed, the patient was discharged after 24 days in hospital. Twelve months later, the patient was asymptomatic, the cardiothoracic ratio decreased to 48% on chest radiography and computed tomography revealed no reaccumulation of pericardial effusion. This case illustrates a potential relationship between enlarged kidneys in autosomal dominant polycystic kidney disease and pericardial effusion.

A case of bullous pemphigoid and renal disease after dipeptidyl peptidase 4 inhibitor administration.

A 62-year-old man with type 2 diabetes was admitted because of a decrease in estimated glomerular filtration rate from 72 to 17.5 mL/min/1.73 m2 in 10 years and development of widespread bullous skin lesions. His hemoglobin A1c level had been maintained at 6.0-7.0% for 10 years with a dipeptidyl peptidase (DPP)-4 inhibitor. Skin biopsy showed typical bullous pemphigoid, and kidney biopsy showed tubulointerstitial nephritis with eosinophilic infiltration and glomerular endothelial cell proliferation. After discontinuing the DPP-4 inhibitor, skin lesions improved, and renal decline slowed. This case indicates that DPP-4 inhibitors can cause not only skin lesions but also renal disease.

A Case of Glomerular Microangiopathy-like Nephropathy Caused by Hyperthyroidism.

A 49-year-old Japanese woman was admitted to our hospital with weight loss of 15 kg, nephrotic-range proteinuria (4.5 g/g.Cre), and hematuria over a 6-month period. She had received two doses of the COVID-19 vaccine one year before the onset of the disease, after which the estimated glomerular filtration rate increased. Laboratory tests and other tests led to a diagnosis of hyperthyroidism, and a kidney biopsy showed thrombotic microangiopathy-like glomerular microangiopathy comprising mainly glomerular endothelial cell damage. Thiamazole (30 mg) was started for the hyperthyroidism. Three months later, the thyroid function normalized, and two months later, the proteinuria and hematuria disappeared, suggesting that COVID-19 vaccination and these events were related.

Syphilis-related Membranous Nephropathy in a 35-year-old Woman.

A 35-year-old woman was admitted for the examination of lower leg edema and proteinuria. A kidney biopsy showed membranous nephropathy (MN) with fine granular deposits of IgG along the glomerular capillary and poor spike formation, differing from primary MN in the presence of positive IgG3 and C1q. Lupus nephritis was excluded because serum complement and anti-dsDNA antibody, anti-Smith antibody, and anti-cardiolipin antibody tests were negative. The serological test for syphilis was positive, as was the Treponema pallidum hemagglutination test. The patient was diagnosed with syphilis, and the proteinuria disappeared with antibiotic treatment. In MN with positive IgG3 and C1q, syphilis nephropathy may be a differential diagnosis.

Dipeptidyl peptidase-4 inhibitor-related renal disease.

BACKGROUND: Dipeptidyl peptidase-4 (DPP-4) inhibitors are widely used to treat type 2 diabetes (T2D). Lowering blood glucose is expected also to reduce the progression of diabetic nephropathy. We experienced a patient with T2D who achieved good glycemic control with a DPP-4 inhibitor but experienced rapid deterioration of renal function. Therefore, we performed a retrospective study of similar patients treated at our hospital. METHODS: Out of 56 patients with biopsy-proven diabetic nephropathy who underwent native kidney biopsy at Toranomon Hospital from January 2018 through December 2022, we selected 22 patients who had been receiving DPP-4 inhibitors for at least 9 months at the time of kidney biopsy. Of these patients, we evaluated 16 diagnosed with class IIa diabetic nephropathy according to Tervaert's pathologic classification. The yearly estimated glomerular filtration rate (eGFR) slope in the 16 patients was arranged from the highest to the lowest slope. Ten patients with a large eGFR slope had thrombotic microangiopathy (TMA)-like lesions characterized by glomerular endothelial cell proliferation and GBM duplication on kidney biopsy (group A), whereas the remaining 6 patients did not have TMA-like lesions (group B). RESULTS: Group A had a median (interquartile range [IQR]) eGFR of 18.2 (16.2, 26.2) and a yearly median (IQR) eGFR slope of -11.2 (-17.6, -9.2) mL/min/1.73 m2 after of DPP-4 administration, whereas group B had a median (IQR) eGFR of 31.5 (21.9, 34.8) mL/min/1.73 m2 and a yearly median (IQR) eGFR slope of -1.6 (-3.1, -0.3). Renal function declined significantly more rapidly in group A than in group B, and proteinuria was higher in group A than in group B (median [IQR], 3.4 [2.6, 4.4] g/day vs 0.8 [0.4, 1.3] g/day, respectively). Five patients in group A progressed to dialysis during follow-up, but none of the patients in group B did. Median (IQR) hemoglobin A1c was 6.2 % (6.0 %, 6.6 %) in group A and 5.8 % (5.7 %, 6.6 %) in group B. CONCLUSION: DPP-4 inhibitors promote vascular endothelial regeneration, but when this effect occurs in the glomerulus, glomerular endothelial cell proliferation leads to TMA-like lesions, which may cause an increase in proteinuria and rapid decline in renal function.

Apolipoprotein E-associated Lipoprotein Glomerulo-tubulopathy.

A 32-year-old man was admitted for the evaluation of proteinuria (5.69 g/day). A light microscopic examination showed markedly dilated glomerular capillary loops with vacuolated areas in many glomeruli, and vacuolated areas were seen on peritubular capillaries in the tubulointerstitium. When electron microscopy specimens prepared by pre-fixation with glutaraldehyde and post-fixation with osmium tetroxide were used for oil red staining, the deposition was confirmed on the affected areas. A genetic analysis of apoE showed that the lipoprotein glomerulopathy was due to apoE-Sendai (Arg145Pro, p.R163P) heterozygosity, which was found in not only the patient but also his mother and twin brother.

Public support for patients with intractable diseases in Japan: impact on clinical indicators from nationwide registries in patients with autosomal dominant polycystic kidney disease.

BACKGROUND: Clinical practice guidelines recommend antihypertensive and tolvaptan therapies for patients with autosomal dominant polycystic kidney disease (ADPKD) in Japan. However, tolvaptan therapy may pose an economic burden. The Japanese Ministry of Health, Labour and Welfare supports patients with intractable diseases. This study aimed to confirm the impact of the intractable disease system in Japan on the clinical treatment of ADPKD. METHODS: We analyzed the data of 3768 patients with ADPKD having a medical subsidy certificate from the Japanese Ministry of Health, Labour and Welfare in 2015-2016. The following quality indicators were use: the adherence rate to the 2014 clinical practice guideline for polycystic kidney disease (prescription rates of antihypertensive agents and tolvaptan in this cohort) and the number of Japanese patients with ADPKD nationwide started on renal replacement therapy in 2014 and 2020. RESULTS: Compared with new applications from 2015 to 2016, the prescription rates of antihypertensives and tolvaptan for the indicated patients at the 2017 renewal application increased by 2.0% (odds ratio = 1.41, p = 0.008) and 47.4% (odds ratio = 10.1, p > 0.001), respectively. These quality indicators improved with antihypertensive treatment, especially in patients with chronic kidney disease stages 1-2 (odds ratio = 1.79, p = 0.013) and in those aged < 50 years (odds ratio = 1.70, p = 0.003). The number of patients with ADPKD who were started on renal replacement therapy in Japan decreased from 999 in 2014 to 884 in 2020 in the nationwide database (odds ratio = 0.83, p < 0.001). CONCLUSIONS: The Japanese public intractable disease support system contributes to improvement of ADPKD treatment.

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.

Can Takayasu Arteritis Cause Hydronephrosis?

A 74-year-old woman was admitted because of malaise and a low-grade fever. Her C-reactive protein level was 0.96 mg/dL. Computed tomography (CT) revealed diffuse uniform thickening of the arterial wall from the abdominal aorta to the common iliac artery and right hydronephrosis. 18F-fluordesoxyglucose positron emission tomography-CT showed an accumulation in the same area. These findings suggested Takayasu arteritis and retroperitoneal fibrosis as differential diagnoses. Takayasu arteritis is characterized by thickening of the arterial walls, and retroperitoneal fibrosis is characterized by membranous lesions covering the outer surface of the arterial walls. Thus, Takayasu arteritis was deemed the most likely diagnosis. Steroid treatment was effective.

Successful peficitinib monotherapy for the new-onset skin manifestations of rheumatoid vasculitis after long-term treatment with tocilizumab for rheumatoid arthritis.

Rheumatoid vasculitis (RV) is a severe extra-articular systemic manifestation of rheumatoid arthritis (RA). Its prevalence has been decreasing for decades because of improved early diagnosis of RA and advances in RA treatment, but it remains a life-threatening disease. The standard treatment for RV has been a glucocorticoid and disease-modifying antirheumatic drugs. Biological agents, including antitumour necrosis factor inhibitors, are also recommended for refractory cases. However, there are no reports of Janus kinase (JAK) inhibitor use in RV. We experienced a case of an 85-year-old woman with a 57-year history of RA who had been treated with tocilizumab for 9 years after receiving three different biological agents over 2 years. Her RA seemed to be in remission in her joints, and her serum C-reactive protein had decreased to 0.0 mg/dL, but she developed multiple cutaneous leg ulcers associated with RV. Because of her advanced age, we changed her RA treatment from tocilizumab to the JAK inhibitor peficitinib in monotherapy, after which the ulcers improved within 6 months. This is the first report to indicate that peficitinib is a potential treatment option for RV that can be used in monotherapy without glucocorticoids or other immunosuppressants.