Malignant hypertension in IgA nephropathy was not associated with background pathological phenotypes of glomerular lesions

A new pathological perspective on thrombotic microangiopathy

Thrombotic microangiopathy (TMA) refers to a condition caused by microvascular injury that includes thrombosis, hemolytic anemia, and thrombocytopenia. There are two classic TMAs, hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura, as well as an atypical HUS (aHUS). aHUS includes a broad spectrum of disorders with diverse etiologies and shares clinical manifestations with classic TMA; however, it frequently lacks typical clinical and laboratory findings. These traits can confuse clinicians and pathologists in terms of renal pathologic diagnosis, especially in cases where TMA is associated with other glomerulopathies or hypertensive renal disease. In this review, new paradigms for classifying TMA and the diversity of histopathologic changes including associated renal diseases are discussed. Renal biopsy is an important and useful diagnostic tool for diagnosing TMA and identifying TMA changes in other renal diseases, including hypertension. Adopting the term “TMA features” for TMA-like changes in glomerulus or artery/arteriole in addition to the pathological diagnosis of glomerulopathy would be informative to clinicians for a prompt diagnosis and treatment of aHUS.

Glomerular endothelial activation, C4d deposits and microangiopathy in immunoglobulin A nephropathy

Immunoglobulin A nephropathy (IgAN) is considered as mesangiopathy since it initiates in the mesangium; however, other glomerular components are involved and the glomerular capillary wall offers the first contact to circulating macromolecular IgA1. Acute and active forms of IgAN are associated with endocapillary hypercellularity and vascular damage of various degrees, in severe cases with microangiopathy (MA) without or with thrombosis [thrombotic microangiopathy (TMA)]. Vascular damage activates complement and coagulation cascades. A defective complement regulation has recently been detected in active and progressive cases of IgAN. C4d deposits in renal biopsies have been found to be an early risk factor. These observations have raised interest in manifestation of MA and TMA in progressive cases of IgAN. MA-TMA lesions have been found in various percentages (2-53%) of patients with IgAN according to patients' selection and pathology definition of TMA. The association with hypertension (HTN) was so strong that it led to the hypothesis that MA/TMA in IgAN was a mere consequence of severe HTN. Old and new clinical and experimental data indicate that in IgAN the interaction of the glomerular capillary wall with immune reactants and complement uncontrolled activation leading to C4b deposits favours the development of MA-TMA, which plays a role in progression and renal function decline. The central role of complement activation is relevant also for the new therapeutic interventions offered by the pharma.

A rare case of malignant hypertension with splenic rupture and thrombotic microangiopathy: A case report

INTRODUCTION

Thrombotic microangiopathy (TMA) is characterized by endothelial injury followed by formation of multiple microthrombi in the target organs due to various causes, including malignant hypertension (MHT). Here, we reported a rare case of MHT with splenic TMA changes.

CASE CONCERNS

A 27-year-old Chinese Han male with a history of hypertension and proteinuria, admitted to our hospital because of renal failure with MHT and thrombocytopenia.

DIAGNOSIS

This case diagnosed with TMA based on the patient's MHT and thrombocytopenia. The patient final diagnosis was confirmed by the spleen pathological findings, other differential diagnoses were ruled out.

INTERVENTIONS

The patient was treated with hemodialysis and intravenous antihypertensive agents, and his condition gradually improved. However, he suddenly complained of abdominal pain and went into hemorrhagic shock, which was due to spontaneous spleen rupture on the third day of hospitalization. The pathological evidence after splenectomy showed splenic TMA.

OUTCOMES

Hemodialysis was continued and the blood pressure was under control until his discharge from our hospital.

CONCLUSION

Spontaneous splenic rupture could be a rare and critical complication associated with MHT-induced TMA, and it requires careful clinical attention.

Clinicopathological analysis of IgA nephropathy combined with other glomerular diseases

It is not rare to find Immunoglobulin A (IgA) nephropathy (IgAN) combined with other glomerular diseases, which can be called compound IgAN (cIgAN). Till now, clinical-pathological investigation of cIgAN was lacking, especially the severity of "background IgAN lesions." This research aimed to investigate the incidence, clinical and pathological characteristics of cIgAN, and thus improve the understanding of the clinical significance of this combination.Patients with cIgAN diagnosed in Peking University People's Hospital from November 2012 to April 2018 were retrospectively analyzed. Patients with IgAN without compound glomerular diseases (sIgAN) were enrolled as a control group.Among 1407 patients diagnosed with IgAN, 80 (5.69%) were cIgAN patients. Compared with sIgAN, cIgAN patients had a significantly lower prevalence of microscopic hematuria and more urine protein. There were 10 pathological types of glomerular diseases combined with IgAN, led by diabetic nephropathy 37 (46.25%) and membranous nephropathy 14 (17.5%). Histologically, although the mesangial hypercellularity was comparable in 2 groups, cIgAN patients had a lower prevalence of endocapillary proliferation, segmental glomerulosclerosis, and cellular or fibrocellular crescents formation, as well as weaker immunofluorescence intensity for IgA and C3 (all P < .05). Eight out of 27 (29.63%) cIgAN patients with follow-up data (5-48 months) developed irreversible end-stage renal disease requiring dialysis.The order of incidence of concomitant diseases was similar to that of the pure diseases. The "background IgAN associated lesions" except mesangial hypercellularity were relatively mild in cIgAN group. Those might suggest that in some cases, IgAN seems to be a chance finding, and the combined diseases may play a more important role in the clinicopathological features of the patients than the nephritis caused by IgA deposition. While diagnosing IgAN, other combined glomerular diseases need to be carefully considered by nephrologists and pathologists.

[IgA nephropathy: Unusual forms]

IgA nephropathy can have various initial presentation and evolutive characteristics. In this article, specific forms of IgA nephropathy are described, such as hypertensive emergency, nephrotic syndrome, rapidly progressive glomerulonephritis, monotypic IgA deposits, or IgA nephropathy associated with inflammatory diseases. Identification of these specific forms is needed to better characterize and treat these rare pathologies.

Elevated soluble VEGF receptor sFlt-1 correlates with endothelial injury in IgA nephropathy

BACKGROUND

Endothelial injury, which may present clinically as hypertension, proteinuria and increased von Willebrand Factor (vWF) level, is a common manifestation in IgA nephropathy (IgAN). However, causal factors for endothelial injury in IgAN are not completely understood. An imbalance of vascular endothelial growth factor/Soluble fms-like tyrosine kinase-1 (VEGF/sFlt-1) has been observed in many diseases with endothelial dysfunction, including pre-eclampsia and diabetic retinopathy, but whether it contributes to endothelial injury in IgAN requires further exploration.

METHODS

Initially, 96 IgAN patients and 22 healthy volunteers were enrolled as a discovery cohort. VEGF/sFlt-1, sFlt-1 and VEGF levels were compared between patients with IgAN and healthy volunteers to explore the underlying factors that contribute to endothelial injury in IgAN. The identified contributor (sFlt-1) was further confirmed in a replication cohort, which included 109 IgAN patients and 30 healthy volunteers. Correlations of sFlt-1 with hypertension, proteinuria, Oxford-E score and plasma vWF were further evaluated in the combined 205 patients with IgAN.

RESULTS

VEGF/sFlt-1 levels were significantly lower in IgAN patients than healthy volunteers (0.33±0.27 vs. 0.43±0.22, p = 0.02) in the discovery cohort. Within the ratio, plasma sFlt-1 levels were significantly elevated (101.18±25.19 vs. 79.73±18.85 pg/ml, p<0.001), but plasma VEGF levels showed no significant differences. Elevated sFlt-1 levels in the replication cohort were confirmed in IgAN patients (93.40±39.78 vs. 71.92±15.78 pg/ml, p<0.001). Plasma sFlt-1 levels in IgAN patients correlated with proteinuria (severe (>3.5 g/d) vs. moderate (1-3.5 g/d) vs. mild (<1 g/d) proteinuria: 115.95±39.09 vs. 99.89±28.55 vs. 83.24±33.92 pg/ml; severe vs. mild: p<0.001, moderate vs. mild p = 0.001, severe vs. moderate: p = 0.014), hypertension (with vs. without hypertension: 107.87±31.94 vs. 87.32±32.76 pg/ml, p = 0.015) and vWF levels (r = 0.161, p = 0.021).

CONCLUSIONS

The present study found elevated sFlt-1 in IgAN patients and further identified its correlation with proteinuria, hypertension and vWF levels. These results suggested that elevated sFlt-1 contributes to endothelial injury in IgAN.

Association of C4d deposition with clinical outcomes in IgA nephropathy

BACKGROUND AND OBJECTIVES

Several studies have suggested that activation of the complement system is a contributing pathogenic mechanism in IgA nephropathy (IgAN). C4d staining is an inexpensive and easy-to-perform method for the analysis of renal biopsies. This study aimed to assess the clinical and prognostic implications of C4d staining in IgAN.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This retrospective cohort study included 283 patients with IgAN in 11 hospitals in Spain who underwent a renal biopsy between 1979 and 2010. The primary predictor was mesangial C4d staining. Secondary predictors included demographic, clinical, and laboratory characteristics, and Oxford pathologic classification criteria. The primary end point was the cumulative percentage of patients who developed ESRD, defined as onset of chronic dialysis or renal transplantation. C4d was analyzed by immunohistochemical staining using a polyclonal antibody. Kaplan-Meier and Cox proportional hazards analyses were performed to evaluate the effect of C4d staining on renal survival.

RESULTS

There were 109 patients (38.5%) and 174 patients (61.5%) who were classified as C4d positive and C4d negative, respectively. Renal survival at 20 years was 28% in C4d-positive patients versus 85% in C4d-negative patients (P<0.001). Independent risk factors associated with ESRD were as follows: proteinuria (hazard ratio [HR] per every 1 g/d increase. 1.16; 95% confidence interval [95% CI], 1.03 to 1.31; P=0.01), eGFR (HR per every 1 ml/min per 1.73 m(2) increase, 0.96; 95% CI, 0.94 to 0.97; P<0.001), T2 Oxford classification (tubular atrophy/interstitial fibrosis, >50%; HR, 4.42; 95% CI, 1.40 to 13.88; P=0.01), and C4d-positive staining (HR, 2.45; 95% CI, 1.30 to 4.64; P=0.01).

CONCLUSIONS

C4d-positive staining is an independent risk factor for the development of ESRD in IgAN. This finding is consistent with the possibility that complement activation is involved in the pathogenesis of this disease.

Clinicopathological and immunohistological features in childhood IgA nephropathy: a single-centre experience

Background

IgA nephropathy is a glomerular disease diagnosed by renal biopsy and is characterized by a highly variable course ranging from a completely benign condition to rapidly progressive renal failure. We aimed to evaluate the clinical, histopathological and inflammatory characteristics of children with IgA nephropathy.

Methods

Data of 37 patients with IgA nephropathy diagnosed between the years 1980 and 2008 were retrospectively reviewed. Immunohistochemistry was performed in 24 patients. Expression of CD3, CD4, CD8, CD20, CD68, IL-1β, IL-10, IL-17, TGF-β, TNF-α and the newly proposed tubulointerstitial fibrosis marker nestin were evaluated.

Results

The median age at diagnosis was 10 years. Recurrent macroscopic haematuria (66%) was the most common clinical manifestation, and 35% of the patients had synpharyngitic presentation. A significant correlation was found between proteinuria and increase in mesangial matrix (r = 0.406, P = 0.013). The presence of CD4+ T lymphocytes and CD68+ macrophages were also significantly associated with proteinuria >1 g/day. While cytokines IL-1β, IL-10 and TNF-α were mainly expressed in tubular epithelial cells, TGF-β was evident in glomeruli but they had no correlation to clinical features and severity of the disease. Nestin was detected at the tubules in almost half of the patients with no correlation to proteinuria and tubulointersititial fibrosis.

Conclusions

We found a correlation between proteinuria and mesangial matrix expansion. The presence of CD4+ T-lymphocytes and CD68+ macrophages were also significantly associated with proteinuria >1 g/day. Although there are many evidences, for immunological basis of IgA nephropathy, the immunological markers were not fully expressed in children to evaluate glomerular and tubulointerstitial inflammation, and progression of the disease. Further studies with the extended number of children are needed to shed light on the immunological basis of the disease.

Hemolytic-uremic syndrome, malignant hypertension and IgA nephropathy: successful treatment with plasma exchange therapy

A young patient with hemolytic-uremic syndrome and malignant hypertension with serious deterioration of renal function is described whose biopsy specimen showed additional IgA mesangial deposits. The patient responded to steroid treatment and to plasma exchange therapy without the need of hemodialysis sessions. In the following years, he achieved clinical remission and his blood pressure was in normal ranges without any further complications. IgA glomerulonephritis is rarely associated to hemolytic-uremic syndrome and malignant hypertension, with only a few previously described cases. We present an overview of potential pathophysiological connections between these diseases.

A clinicopathologic study of thrombotic microangiopathy in IgA nephropathy

Thrombotic microangiopathy (TMA) occurs in IgA nephropathy, but its clinical significance is not well described. We retrospectively examined a series of 128 patients diagnosed with IgA nephropathy between 2002 and 2008 who had a mean follow-up of 44±27 months. In our series, 53% presented with lesions of TMA, acute or organized, in arteries and/or arterioles. Among patients with TMA, 4% were normotensive, 25% had controlled hypertension, and 71% had uncontrolled hypertension. Of those with uncontrolled hypertension, 26% had malignant hypertension. Histologically, the group with TMA had a significantly greater percentage of sclerotic glomeruli and worse tubulointerstitial fibrosis than those of the group without TMA. However, a significant minority of patients had near-normal histology, with minimal tubular atrophy (20%) and/or <20% interstitial fibrosis (24%). TMA rarely occurred in the absence of significant proteinuria. During follow-up, a doubling of serum creatinine or ESRD occurred in all patients with laboratory evidence of TMA, in 42% of those with morphologic evidence but no laboratory evidence of TMA, and in 11% of those without TMA. In summary, lesions of TMA are frequent in IgA nephropathy and may occur in normotensive patients with near-normal renal histology. Although the pathophysiologic mechanisms involved remain undetermined, the current study rules out severe hypertension or advanced renal disease as sole causes.