Quantitative assessment of glomerular basement membrane collagen IV α chains in paraffin sections from patients with focal segmental glomerulosclerosis and Alport gene variants

Focal segmental glomerulosclerosis (FSGS) lesions have been linked to variants in COL4A3/A4/A5 genes, which are also mutated in Alport syndrome. Although it could be useful for diagnosis, quantitative evaluation of glomerular basement membrane (GBM) type IV collagen (colIV) networks is not widely used to assess these patients. To do so, we developed immunofluorescence imaging for collagen α5(IV) and α1/2(IV) on kidney paraffin sections with Airyscan confocal microscopy that clearly distinguishes GBM collagen α3α4α5(IV) and α1α1α2(IV) as two distinct layers, allowing quantitative assessment of both colIV networks. The ratios of collagen α5(IV):α1/2(IV) mean fluorescence intensities (α5:α1/2 intensity ratios) and thicknesses (α5:α1/2 thickness ratios) were calculated to represent the levels of collagen α3α4α5(IV) relative to α1α1α2(IV). The α5:α1/2 intensity and thickness ratios were comparable across all 11 control samples, while both ratios were significantly and markedly decreased in all patients with pathogenic or likely pathogenic Alport COL4A variants, supporting validity of this approach. Thus, with further validation of this technique, quantitative measurement of GBM colIV subtype abundance by immunofluorescence, may potentially serve to identify the subgroup of patients with FSGS lesions likely to harbor pathogenic COL4A variants who could benefit from genetic testing.

Clinicopathological Characteristics and Impacts on Clinical Outcomes of Thrombotic Microangiopathy Lesions in Patients with Immunoglobulin A Nephropathy in Thailand

INTRODUCTION

More reports of thrombotic microangiopathy (TMA) in immunoglobulin A (IgA) nephropathy suggest its association with poor clinical outcomes. However, the prevalence and clinical significance of TMA in IgA nephropathy have not been widely studied in different populations.

METHODS

Kidney biopsies of all patients with primary IgA nephropathy from 1995 to 2015 at the King Chulalongkorn Memorial Hospital, Thailand, were retrospectively reviewed and reclassified by two pathologists following the Oxford MEST-C classification. TMA lesions were detected based solely on light microscopic findings. Associations between the presence of TMA and clinical data, other pathologic findings, and clinical outcomes were studied.

RESULTS

Among 267 patients with primary IgA nephropathy, 166 had adequate clinical data and kidney tissues for the analysis. TMA was observed in 21 patients (13%) and was associated with higher mean arterial pressure (MAP), history of malignant hypertension, higher proteinuria, and lower estimated glomerular filtration rate (eGFR) at diagnosis compared to those without TMA. According to the Oxford MEST-C classification, TMA showed a significant association with severe tubular atrophy/interstitial fibrosis (T2) but not with mesangial hypercellularity (M1), endocapillary hypercellularity (E1), segmental glomerulosclerosis (S1), or crescents (C1-2). After a median follow-up of 50 months, patients with TMA had a significantly higher risk of progression to end-stage kidney disease (ESKD) (hazard ratio [HR] 5.8, 95% confidence interval [CI]: 3.1-10.9) and all-cause mortality (HR 3.4, 95% CI: 1.3-8.8). After adjusting for baseline eGFR, MAP, proteinuria, and other pathological lesions, TMA remained an independent predictor of ESKD (adjusted HR 2.4, 95% CI: 1.1-5.4).

CONCLUSIONS

Kidney TMA in IgA nephropathy is associated with advanced disease stages, carries a poor prognosis, and thus should be considered in the pathological classification of IgA nephropathy.

Pathological Approach to Kidney Allograft Infection

Infectious agents can pose a significant challenge in kidney transplantation, as they have the potential to cause direct infections in the transplanted kidney. These infections can lead to a decline in kidney function and reduce the longevity of the transplanted kidney. Common post-transplant allograft infections include bacterial pyelonephritis and the BK virus infection, while adenovirus, JC virus, and cytomegalovirus are less frequent but can also lead to significant allograft dysfunctions. The histopathological features of these infections are characterized by the infiltration of inflammatory cells in the kidney interstitial area and the presence of viral nuclear inclusions or cytopathic changes in the renal tubular epithelial cells. The confirmation of causative organisms can be achieved by immunohistochemical staining or the visualization of viral particles using electron microscopic examination. However, these methods typically require a longer turnaround time and are not readily available in developing countries, unlike standard hematoxylin-eosin staining. Notably, the differential diagnosis of interstitial inflammation in kidney allografts almost always includes T cell-mediated rejection, which has a different treatment approach than allograft infections. The aim of this review was to prompt clinicians to identify diverse pathological alterations as observed in kidney allograft biopsies, thereby facilitating further investigations and the management of suspected kidney allograft infections.

ANCA Associated Glomerulonephritis Following SARS-CoV-2 Vaccination: A Case Series and Systematic Review

Vaccines against SARS-CoV-2 (COVID-19) proved beneficial for COVID-19 disease attenuation and preventing virus spreading. Cumulative reports of the rarity of antineutrophil cytoplasmic autoantibodies (ANCA)-associated vasculitis (AAV) raise concerns about its relationship with COVID-19 vaccination. Several case reports described ANCA-associated pauci-immune glomerulonephritis (ANCA-GN) following COVID-19 vaccination with some uniqueness. We systematically reviewed COVID-19 vaccine-induced ANCA-GN from PubMed, SCOPUS, and Cochrane library databases until 1 January 2023 according to PRISMA guidelines and presented our three cases. Twenty-six cases from 25 articles, including our 3 cases, were analyzed. Most cases were diagnosed following the second dose of the COVID-19 vaccine (59%) with a median (IQR) interval onset of 14 (16) days. The highest prevalence was related to the mRNA-type vaccine. Anti-myeloperoxidase (MPO) ANCA was far more common than the other ANCAs, with various positive autoantibodies. Fourteen cases (out of 29 cases, 48%) had extra-kidney AAV manifestation. Although severe kidney injury was observed in 10/29 (34%), remission was achieved in 89% (25/28) with no death. The mechanisms of the vaccine-inducing ANCA-GN were postulated here. Since ANCA-GN after the COVID-19 vaccine was rare, the benefit of the COVID-19 vaccine could outweigh the risk of ANCA-GN side effects in the pandemic era.

Detectable serum IgM monoclonal gammopathy in non-hepatitis-associated mixed cryoglobulinemic glomerulonephritis: A case report and literature review

Cryoglobulinemia is the presence of circulating cryoglobulin which can cause systemic vasculitis and glomerulonephritis. Monoclonal gammopathy of renal significance is strongly associated with type I cryoglobulinemia, but the role of detectable serum monoclonal gammopathy in mixed (type II) cryoglobulinemia is not clearly established. We report a case of a 71-year-old woman who presented with skin rash, leg edema, and azotemia. Investigations showed a positive result for rheumatoid factor, low complement C4 level, positive result for serum cryoglobulin, and positive M-spike on serum protein electrophoresis and IgM kappa monoclonal gammopathy on serum immunofixation. Kidney biopsy revealed membranoproliferative glomerulonephritis, polytypic IgM-dominant deposits in an immunofluorescence study, and microtubular substructures in an electron microscopic study. After an extensive workup, no evidence of myeloma or lymphoma was found. A diagnosis of monoclonal gammopathy of renal significance-associated mixed cryoglobulinemic glomerulonephritis was made. Due to the detectable IgM kappa monoclonal gammopathy in the patient's serum, clonal-directed therapy was administered. The patient had been in clinical remission after treatment with clone-directed therapy with cyclophosphamide and steroids. The literature review for cases of type II cryoglobulinemic glomerulonephritis that have detectable serum monoclonal gammopathy are summarized in this study.

Tenofovir alafenamide nephrotoxicity: a case report and literature review

Background

Tenofovir alafenamide (TAF), a novel prodrug of tenofovir (TFV), has become the preferred drug for the treatment of HIV-1 and chronic hepatitis B infection in clinical practice. Results from clinical trials showed that it had better renal and bone mineral outcomes compared to tenofovir disoproxil fumarate (TDF). However, as we have seen with TDF, side effects from the new medication can be more prevalent and recognized after extensive use in real world situations. Sporadic cases of acute kidney injury in patients using TAF have started to emerge.

Case presentation

We report a case of 49-year-old Thai, HIV treatment-experienced female with hypertension presented with worsening renal function after switching her antiretroviral regimen from TDF, emtricitabine (FTC), and lopinavir/ritonavir (LPV/r) to TAF, FTC and dolutegravir (DTG) for 3 months. Kidney biopsy showed distinctive picture of tenofovir nephrotoxicity with acute tubular injury and mitochondrial injury. The possible causes of acute kidney injury and nephrotoxicity from TAF for this patient were discussed. We have extensively reviewed all published case reports of TAF-associated nephrotoxicity and summarized the essential information in this article.

Conclusion

Although TAF has less nephrotoxicity compared with TDF; renal function should always be monitored after the initiation of both drugs. Future large cohort studies are required to identify the risk factors of TAF-associated nephrotoxicity and to design an effective preventive strategy.

The first report of kidney transplantation in a human immunodeficiency virus-positive recipient in Thailand and literature review: Encouragement for developing countries in Southeast Asia

Patients with human immunodeficiency virus infection are at risk of chronic kidney disease and end-stage renal disease. Human immunodeficiency virus infection impedes patients' accessibility to transplantation in Thailand and other developing countries in Southeast Asia, where the burdens of human immunodeficiency virus infection and chronic kidney disease are rapidly increasing. We report the successful kidney transplantation in a human immunodeficiency virus-positive recipient in Thailand and provide brief information about the current knowledge of human immunodeficiency virus medicine and transplantation that are needed for conducting kidney transplantations in such patients. Patient selection and evaluation, the choice of antiretroviral therapy, immunosuppressive regimens, and infectious complications are reviewed and discussed. The aim is to encourage kidney transplantation in end-stage renal disease patients with well-controlled human immunodeficiency virus infection, especially in countries where the prevalence of human immunodeficiency virus infection is high and the accessibility to transplantation is still limited.

Paraganglioma of the organ of Zuckerkandl and FH gene mutation

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Leiomyosarcoma of the renal pelvis diagnosed by percutaneous endoscopic resection

We present a case of leiomyosarcoma arising from the renal pelvis, which is a rare clinical entity. A percutaneous endoscopic resection led to the final histopathological diagnosis. The patient underwent radical nephrectomy and did not receive adjuvant therapy. Based on follow-up CT scans, he remains recurrence-free one year after surgery.

Urinary sulfated glycosaminoglycan insufficiency and chondroitin sulfate supplement in urolithiasis

Familial members of urolithiasis have high risk for stone development. We observed the low sulfated glycosaminoglycan (GAG) excretion in urolithiasis patients and their descendants. In this study, we investigated urinary excretion of sulfated GAG, chondroitin sulfate (CS), heparan sulfate (HS) and hyaluronic acid (HA) in urolithiasis and their children, and explored the effect of CS and HA supplement in urolithic hyperoxaluric rats. The 24-hour urines were collected from urolithiasis patients (28) and their children (40), as well as healthy controls (45) and their children (33) to measure urinary sulfated GAG, CS, HS and HA excretion rate. Our result showed that urinary sulfated GAG and CS were diminished in both urolithiasis patients and their children, while decreased HS and increased HA were observed only in urolithiasis patients. Percentage of HS per sulfated GAG increased in both urolithiasis patients and their children. In hyperoxaluric rats induced by ethylene glycol and vitamin D, we found that CS supplement could prevent stone formation, while HA supplement had no effect on stone formation. Our study revealed that decreased urinary GAG and CS excretion are common in familial members of urolithiasis patients, and CS supplement might be beneficial in calcium oxalate urolithiasis prophylaxis for hyperoxaluric patients.

Furosemide Stress Test as a Predicting Biomarker for Delayed Graft Function in Kidney Transplantation

BACKGROUND

Delayed graft function (DGF) could worsen early and long-term outcomes of kidney transplantation (KT). DGF is caused by several pre-transplantation and perioperative factors in both donors and recipients. At present, there are no biomarkers or tests during the immediate post-KT period that can accurately predict the development of DGF.

MATERIALS AND METHODS

This prospective study was conducted in deceased donor KT (DDKT) at King Chulalongkorn Memorial Hospital, Thailand. All recipients underwent furosemide stress test (FST) by receiving a single dose of intravenous furosemide, 1.5 mg/kg at 3 h after allograft reperfusion. We determined the correlations between DGF (requiring dialysis within the first week after transplantation) and the values of urine volume recorded hourly after FST until 6 h, the parameters of postoperative dynamic tests, including resistive index (RI) of renal arteries and effective renal plasma flow (ERPF), and urine neutrophil gelatinase-associated lipocalin (NGAL).

RESULTS

Of the 59 total DDKT recipients enrolled, 24 developed DGF. The FST is a more accurate biomarker than urine NGAL, RI of renal arteries, and ERPF in the prediction of DGF. The 4-h urine volume less than 350 mL (FST non-responsive) was the best cut-off value in predicting DGF with 87.5% sensitivity, 82.9% specificity, and 82.5% accuracy. Multiple logistic regression analyses showed an odds ratio of 0.993 (0.986-0.999, p = 0.035) for the 4-h urine volume to predict DGF.

CONCLUSIONS

The FST is a simple and accurate biomarker for predicting DGF in early post-KT period. Close monitoring and well prepared dialysis are suggested in patients with urine volume < 350 mL after 4 h of FST. The FST non-responsive patients could be the target for further DGF preventive intervention. ClinicalTrials.gov identifier: NCT03071536.

The Cytochrome P450 3A5 Non-Expressor Kidney Allograft as a Risk Factor for Calcineurin Inhibitor Nephrotoxicity

BACKGROUND

Tacrolimus is mainly metabolized by cytochrome P450 3A5 (CYP3A5), which is expressed in the liver. However, CYP3A5 is also expressed in the kidney tissue and may contribute to local tacrolimus clearance in the kidney allograft. We aimed to evaluate the association between the allograft CYP3A5 genotype and transplant outcomes.

METHODS

We conducted a retrospective cohort study at the King Chulalongkorn Memorial Hospital, Thailand, comparing 2 groups of donor and recipient CYP3A5 genotypes, the expressor (*1/*1 and *1/*3) and the non-expressor (*3/*3). The primary outcomes were allograft complications including calcineurin inhibitor (CNI) nephrotoxicity and acute rejection episode.

RESULTS

Of the 50 enrolled patients, 21 donors were expressors and 29 donors were the non-expressors. Tacrolimus trough concentrations were similar between the 2 genotypes. The incidence of CNI nephrotoxicity was higher in recipients with non-expressor donor genotype compared with the expressor donor genotype (72.4 vs. 33.3%, p = 0.006). CNI nephrotoxicity incidence was not different when recipient's genotypes were compared. Multivariate analysis from Cox-regression showed a hazard ratio of 3.18 (p = 0.026) for CNI nephrotoxicity in the non-expressor compared with the expressor donor. The recipient CYP3A5 genotypes did not significantly contribute to CNI nephrotoxicity. Kaplan-Meier analysis demonstrated the lowest CNI nephrotoxicity-free survival in recipients with the expressor genotype who received allograft from the non-expressor donors (p = 0.005).

CONCLUSION

In conclusion, our results suggest that donor CYP3A5 non-expressor genotype (*3/*3) is a risk for CNI nephrotoxicity.