Steroid-responsive idiopathic glomerular capillary endotheliosis: case report and literature review

Glomerular Endotheliosis in COVID-19-Associated Acute Kidney Injury

Acute kidney injury (AKI) has been seen in patients hospitalized with a SARS-CoV-2 (COVID-19) infection,but the pathophysiology of glomerular injury is not yet fully understood. We present a case of COVID-19-related “glomerular endotheliosis” in which a 51-year-old female with a 13-year history of class IV lupus nephritis was admitted for COVID-19 pneumonia. Her lupus nephritis had been in complete renal remission for the past 10 years with a baseline serum creatinine level of 1.3 mg/dL and no proteinuria. Her serological workup, including complement levels, was unremarkable. Due to the worsening renal function and persistent proteinuria, she underwent a kidney biopsy that revealed diffuse glomerular endothelial cell swelling, also known as glomerular endotheliosis. Her clinical course unfortunately deteriorated and she succumbed to acute respiratory distress syndrome. As circulating anti-angiogenic factors may contribute to the pathogenesis of endothelial dysfunction leading to glomerular endotheliosis, we propose that a similar circulating antiangiogenic factor may have been triggered by COVID-19 and played a role in our patient’s progressive renal failure.

Ockham's razor defeated: about two atypical cases of hemolytic uremic syndrome

Background

Medical investigation is a favorite application of Ockham’s razor, in virtue of which when presented with competing hypotheses, the solution with the fewest assumptions should be privileged. Hemolytic uremic syndrome (HUS) encompasses diseases with distinct pathological mechanisms, such as HUS due to shiga-like toxin-producing bacteria (STEC-HUS) and atypical HUS, linked to defects in the alternate complement pathway. Other etiologies such as Parvovirus B19 infection are exceptional. All these causes are rare to such extent that we usually consider them mutually exclusive. We report here two cases of HUS that could be traced to multiple causes.

Cases presentation

Case 1 presented as vomiting and diarrhea. All biological characteristics of HUS were present. STEC was found in stool (by PCR and culture). After initial remission, a recurrence occurred and patient was started on Eculizumab. Genetic analysis revealed the heterozygous presence of a CFHR1/CFH hybrid gene. The issue was favorable under treatment.

In case 2, HUS presented as fever, vomiting and purpura of the lower limbs. Skin lesions and erythroblastopenia led to suspect Parvovirus B19 primo-infection, which was confirmed by peripheral blood and medullar PCR. Concurrently, stool culture and PCR revealed the presence of STEC. Evolution showed spontaneous recovery.

Conclusions

Both cases defy Ockham’s razor in the sense that multiple causes could be traced to a single outcome; furthermore, they invite us to reflect on the physiopathology of HUS as they question the classical distinction between STEC-HUS and atypical HUS. We propose a two-hit mechanism model leading to HUS. Indeed, in case 1, HUS unfolded as a result of the synergistic interaction between an infectious trigger and a genetic predisposition. In case 2 however, it is the simultaneous occurrence of two infectious triggers that led to HUS. In dissent from Ockham’s razor, an exceptional disease such as HUS may stem from the sequential occurrence or co-occurrence of several rare conditions.

Steroid Responsive Atypical Hemolytic Uremic Syndrome Triggered by Influenza B Infection

Atypical hemolytic uremic syndrome (aHUS) is characterized by uncontrolled complement activation leading to thrombotic microangiopathy and severe end-organ damage. The most common trigger for an episode of aHUS in the background of genetic deregulation of the alternative complement pathway is systemic infection. There are only 4 reported cases of aHUS triggered by influenza B thus far. Current accepted therapies for aHUS include plasma exchange and eculizumab. We describe a unique patient with aHUS with a rare membrane cofactor protein mutation triggered by influenza B infection, who achieved complete remission with treatment with high-dose corticosteroids after failure of plasmapheresis.

ABCB1 polymorphisms and steroid treatment in children with idiopathic nephrotic syndrome

BACKGROUND

The most common cause of nephrotic syndrome (NS) is idiopathic nephrotic syndrome (INS), also called nephrosis. Although most patients respond to steroid therapy, there is unequal response to treatment suggesting the involvement of genetic factors. The current study was conducted to evaluate the influence of two single nucleotide polymorphisms (SNPs) in ABCB1 (C3435T and C1236T) on the steroid treatment response in INS children.

MATERIALS AND METHODS

Genotyping of ABCB1 C3435T and C1236T polymorphisms by real time PCR were conducted on 120 INS children, 80 steroid sensitive (SS) and 40 steroid resistant (SR).

RESULTS

A significant difference in the distribution of ABCB1 C3435T and C1236T genotypes was observed between SS and SR patients. C1236T polymorphism was associated with steroid resistance in INS children (odds ratio: 2.27, 95 % confidence interval: 1.2-4.4; P = 0.012). The frequency of the T allele was significantly higher in SR than in SS patients (81.2 vs. 65.6%, respectively). The odds ratio for the C3435T polymorphism in response to steroid treatment was smaller than that of the polymorphism C1236T, and did not reach statistical significance (odds ratio: 1.1, 95 % confidence interval: 0.6-1.9; P = 0.77).

CONCLUSION

Our results suggested that C1236T polymorphism in ABCB1 gene was associated with steroid resistance. A higher proportion of SR children had C1236T TT genotype and T allele, these patients may require other therapeutic strategies.

A brief overview of preeclampsia

Preeclampsia (PE) is a leading cause of maternal mortality and morbidity worldwide. It occurs in women with first or multiple pregnancies and is characterized by new onset hypertension and proteinuria. Improper placentation is mainly responsible for the disease. If PE remains untreated, it moves towards more serious condition known as eclampsia. Hypertension, diabetes mellitus, proteinuria, obesity, family history, nulliparity, multiple pregnancies and thrombotic vascular disease contribute as the risk factors for PE. PE triggered metabolic stress causes vascular injury, thus contributing to the development of cardiovascular disease (CVD) and/or chronic kidney disease (CKD) in future. This risk appears to be increased especially in women with a history of recurrent PE and eclampsia. Clinically increased serum levels of sFlt-1 and decreased placental growth factor (PIGF) and vascular endothelial growth factor (VEGF) represent the severe condition of PE. The clinical findings of sever PE are assorted by the presence of systemic endothelial dysfunction, microangiopathy, the liver (hemolysis, elevated liver function tests and low platelet count, namely HELLP syndrome) and the kidney (proteinuria). The early detection of PE is one of the most important goals in obstetrics.

Genetic polymorphisms influence the steroid treatment of children with idiopathic nephrotic syndrome

BACKGROUND

Idiopathic nephrotic syndrome (INS) is the most frequent type of nephrotic syndrome that occurs in children. Its response to treatment with steroids varies. The aim of this study was to analyze the correlation between steroid metabolism-related genes and the response to steroid treatment.

METHODS

The patient cohort comprised 74 children with INS, of whom were 58 steroid-sensitive (SS) cases and 16 steroid-resistant (SR) cases. The genetic polymorphisms analyzed were those of the CYP3A5 gene (A6986G) and ABCB1 gene (C1236T, G2677T/A, and C3435T), and the polymorphisms between SS and SR children were compared.

RESULTS

C1236T in ABCB1 was associated with steroid resistance in INS children [odds ratio (OR) 2.65, 95 % confidence interval (CI) 1.01-6.94; p = 0.042] The frequency of the T allele was significantly higher in SR subjects than in SS subjects (0.81 vs. 0.62, respectively). A6986G in CYP3A5 showed a trend of association, but this association did not reach statistical significance (OR 2.63, 95 % CI 0.94-7.37; p = 0.059). No significant correlation was found between treatment response and G2677T/A or C3435T in ABCB1.

CONCLUSIONS

Our results indicate that among our pediatric patients with INS the C1236T polymorphism in the ABCB1 gene was associated with steroid resistance, while the A6986G polymorphism in the CYP3A5 gene showed a trend of association, but did not reach statistical significance, requiring further analysis.

Pre-eclampsia and the kidney

Pre-eclampsia is a multisystem disorder that is unique to pregnancy, affecting at least 5% of all gravidas. The mainstay of this diagnosis is a combination of new-onset hypertension and proteinuria. The kidney deserves particular attention because of the physiologic as well as pathologic changes that can affect this vital organ in pregnancy. In fact, there is a major interplay between renal disease and pre-eclampsia. Proteinuria is universal to all cases of pre-eclampsia, yet some cases can progress to acute renal failure. Furthermore, it is well-established that the latter is more frequent in women with underlying renal disease. This chapter reviews the physiologic changes that the human kidney adapts during pregnancy, the impact of pre-eclampsia on the kidney and its function, and the risk of pre-eclampsia in women with chronic renal disease. Two groups that warrant special consideration are pregnant women with systemic lupus erythematosus and those with history of renal transplantation.

The Glomerular Injury of Preeclampsia: Figure 1

Preeclampsia is a pregnancy-specific disorder that complicates approximately 5% of all pregnancies, making it perhaps the most common glomerular disease in the world. It is characterized by new-onset hypertension and proteinuria, in association with a characteristic glomerular lesion, endotheliosis. "Glomerular endotheliosis" represents a specific variant of thrombotic microangiopathy that is characterized by glomerular endothelial swelling with loss of endothelial fenestrae and occlusion of the capillary lumens. Associated thrombosis is unusual. Recent evidence suggests that this unusual glomerular lesion is mediated by a soluble vascular endothelial growth factor receptor that deprives glomerular endothelial cells of the vascular endothelial growth factor that they require, leading to cellular injury and disruption of the filtration apparatus with subsequent proteinuria. This review summarizes the histologic changes and the pathogenesis of the glomerular lesions of preeclampsia.