In search of a better understanding of IgA nephropathy-associated hematuria

A case report and literature review of IgA nephropathy presenting as nephrotic syndrome in polycythemia vera

A 66-year-old non-smoker presented with a 2-week history of new-onset pedal oedema and gross haematuria. On evaluation, he was found to be hypertensive and oedematous with a haemoglobin of 19.1 g/dl, platelet count of 546,000/mm3, and creatinine of 2.6 mg/dl. Urine examination revealed abundant RBCs with 3+ albumin on three separate occasions. His 24-h urine protein level was 3830 mg/day, with a serum cholesterol level of 303 mg/dl. Secondary erythrocytosis and thrombocytosis tests were negative. Bone marrow examination revealed hypercellularity, erythroid hyperplasia, tight clusters of large megakaryocytes, and megakaryocytic hyperplasia suggestive of polycythemia vera. PCR analysis revealed a JAK2V617 F (exon 14) mutation. In view of nephrotic syndrome, azotemia, and microscopic haematuria, a renal biopsy was performed, which revealed features of IgA nephropathy with advanced interstitial fibrosis and tubular atrophy. He was started on angiotensin receptor blockers with hydroxy urea as a part of treatment. This case report highlights the association of glomerular disease with polycythaemia vera and the need of prompt renal biopsy for diagnosis and management.

Predictors of Gross Hematuria After SARS-CoV-2 mRNA Vaccination in Patients with IgA Nephropathy

Key Points

Little is known about the clinical characteristics of patients with immunoglobulin A nephropathy (IgAN) who present with gross hematuria in relation to SARS-CoV-2 mRNA vaccination. The relationship between the clinical features in patients with IgAN at the time of SARS-CoV-2 mRNA vaccination and the subsequent appearance of gross hematuria was investigated. This study demonstrates the clinical significance of microscopic hematuria in patients with IgAN as a predictor of gross hematuria after SARS-CoV-2 mRNA vaccination.

Background

There have been several reports of immunoglobulin A nephropathy (IgAN) patients with gross hematuria and acute deterioration of urinary findings and kidney function after severe acute respiratory syndrome coronavirus 2 mRNA vaccination. Recent case series studies have indicated a possible link between the status of urinary findings at the time of vaccination and the subsequent appearance of gross hematuria. In this study, we aimed to determine whether the status of prevaccination urinary findings was associated with postvaccination gross hematuria in patients already diagnosed with IgAN.

Methods

Outpatients with IgAN who had been followed up before vaccination were included. We analyzed the association between the remission of prevaccination microscopic hematuria (urine sediment <5 red blood cells/high-power field) or proteinuria (<0.3 g/gCr) and postvaccination gross hematuria.

Results

A total of 417 Japanese patients with IgAN (median age, 51 years; 56% female; eGFR, 58 ml/min per 1.73 m2) were included. The frequency of gross hematuria after vaccination was higher in 20 of 123 patients (16.3%) with microscopic hematuria than in 5 of 294 patients (1.7%) without microscopic hematuria before vaccination (P < 0.001). There was no association between prevaccination proteinuria and postvaccination gross hematuria. After adjusting for potential confounders, such as sex (female), age (younger than 50 years), eGFR (≥60 ml/min per 1.73 m2), and histories of tonsillectomy and corticosteroid therapy, prevaccination microscopic hematuria was still associated with postvaccination gross hematuria (odds ratio, 8.98; P < 0.001). As the severity of prevaccination microscopic hematuria increased, the incidence of postvaccination gross hematuria increased (P < 0.001).

Conclusions

Prevaccination microscopic hematuria in patients with IgAN is a major predictor of postvaccination gross hematuria, regardless of potential confounders, including previous treatments of IgAN.

Clinical, pathological characteristics and outcomes of immunoglobulin A nephropathy patients with different ages

AIM

To determine the clinical and pathological differences in immunoglobulin A (IgA) nephropathy (IgAN) with different ages, and to determine whether age is a risk factor for progression of IgAN.

METHODS

This was a single centre retrospective cohort study. Patients with biopsy-diagnosed primary IgAN were stratified into three groups: young-aged (14-29 years), middle-aged (30-49 years) and older-age (≥50 years). The primary outcome was end-stage renal disease (estimated glomerular filtration rate [eGFR] <15 mL/min/1.73 m² , dialysis or renal transplantation) or doubling of the baseline serum creatinine.

RESULTS

A total of 981 patients were enrolled, including 65 (6.6%) patients in older-age group, 517 (52.7%) in middle-aged group and 399 (40.7%) in young-aged group. The older-age group had significantly higher levels of serum IgA, cholesterol, triglycerides and creatinine, and a reduced eGFR. In contrast to the young adults who had a higher percentage of crescent formation in glomeruli, the older-aged patients had more severe chronic pathological changes including global glomerulosclerosis and vascular lesions (p < .01). The cumulative renal survival in the older-age group was slightly shorter than that in the young adult or middle-aged group, but not achieving significant (p > .05). The 3- and 5-year renal survival rates were similar among the three groups. A multivariate Cox regression analysis showed that age was not an independent predictor of an unfavourable prognosis.

CONCLUSION

The IgAN patients with aged 50 years or older had different clinical pathological changes as compared with younger patients. However, aging was not found as an independently predictor of renal progression of IgAN. Prolonged follow up is necessary to confirm this trend.

Decreased Expression of Urinary Mammalian Target of Rapamycin mRNA Is Related to Chronic Renal Fibrosis in IgAN

Background

Renal fibrosis is a common outcome of all pathological types of chronic kidney disease (CKD). However, the noninvasive detection of renal fibrosis remains a challenge.

Methods

We collected urine samples from 154 biopsy-proven IgA nephropathy (IgAN) patients and 61 healthy controls. The expression of mTOR was measured and the correlation with renal function parameter and pathological indicators. The receiver operating characteristic (ROC) curve for the diagnosis of IgAN and renal fibrosis was calculated.

Results

The urinary mammalian target of rapamycin (mTOR) expression was decreased in IgAN patients. The expression of mTOR was correlated with serum creatinine, blood urea nitrogen, estimated glomerular filtration rate, 24 h proteinuria, and cystatin C. Further, the urinary mTOR expression was significantly decreased in severe renal fibrosis patients compared with mild or moderate renal fibrosis patients. Urinary mTOR expression was correlated with score of tubulointerstitial fibrosis (TIF) and score of glomerular sclerosis. The ROC curve showed that mTOR can diagnose IgAN at a cut-off value of 0.930 with the sensitivity of 90.2% and specificity of 73.8% and renal fibrosis at a cut-off value of 0.301 with the sensitivity of 71.7% and specificity of 64.8%.

Conclusion

Urinary mTOR mRNA expression was a potential biomarker for diagnosis of IgAN and renal fibrosis in IgAN patients.

CX3CL1/CX3CR1 Axis, as the Therapeutic Potential in Renal Diseases: Friend or Foe?

The fractalkine receptor chemokine (C-X3-C motif) receptor 1 (CX3CR1) and its highly selective ligand CX3CL1 mediate chemotaxis and adhesion of immune cells, which are involved in the pathogenesis and progression of numerous inflammatory disorders and malignancies. The CX3CL1/CX3CR1 axis has recently drawn attention as a potential therapeutic target because it is involved in the ontogeny, homeostatic migration, or colonization of renal phagocytes. We performed a Medline/PubMed search to detect recently published studies that explored the relationship between the CX3CL1/CX3CR1 axis and renal diseases and disorders, including diabetic nephropathy, renal allograft rejection, infectious renal diseases, IgA nephropathy, fibrotic kidney disease, lupus nephritis and glomerulonephritis, acute kidney injury and renal carcinoma. Most studies demonstrated its role in promoting renal pathopoiesis; however, several recent studies showed that the CX3CL1/CX3CR1 axis could also reduce renal pathopoiesis. Thus, the CX3CL1/CX3CR1 axis is now considered to be a double-edged sword that could provide novel perspectives into the pathogenesis and treatment of renal diseases and disorders.

Long-term outcome of IgA nephropathy patients with recurrent macroscopic hematuria

BACKGROUND/AIMS

The long-term renal outcomes of patients with IgA nephropathy (IgAN) who present with recurrent macroscopic hematuria (RMH) have not been described in previous studies.

METHODS

Patients with biopsy-proven primary IgAN in Jinling Hospital were divided into three groups according to different patterns of macroscopic hematuria (MH): RMH, isolated MH (IMH), and those without a history of MH (NMH).

RESULTS

A total of 1,155 patients were enrolled in the study (158 in the RMH group, 256 in the IMH group, and 741 in the NMH group). At biopsy, patients with RMH were younger, had lower median proteinuria, a lower incidence of hypertension, and a higher estimated glomerular filtration rate than those in the NMH group. Pathologically, patients with RMH had a lower level of mesangial hypercellularity and segmental glomerulosclerosis as well as less tubular atrophy than those with NMH. The demographic and clinical features of patients with IMH fell between patients with RMH and those with NMH. During a median follow-up of 7.9 years, the 5-, 10- and 20-year cumulative renal survival after biopsy, as calculated by K-M methods, were 98, 91, and 91% in the RMH group, 95, 89, and 64% in the IMH group, and 95, 79, and 57% in the NMH group. The renal survival in patients with RMH was significantly better than patients with NMH or IMH.

CONCLUSIONS

The long-term prognosis of patients who present with RMH is significantly better than patients with NMH or IMH.

Primary glomerulonephritis: A review of important recent discoveries

The publication of the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines on the treatment of glomerular diseases in 2012 marked a milestone in this field, as it is the first time that comprehensive guidelines are provided for such disease entities. The current review focuses on major findings, both pathogenesis related and clinical, in the primary glomerulonephritis that have been made after the guidelines came into effect.