De novo CMV-associated collapsing focal segmental glomerulosclerosis in a kidney transplant recipient

Podocytopathies related to either COVID-19 infection or its vaccination, our experience and literature review

Coronavirus disease 2019 (COVID-19) affects several organs including the kidney resulting in acute kidney injury (AKI) and variants of podocytopathies. From the beginning to the middle period of the COVID-19 pandemic, we have collected eight renal biopsies with various renal diseases including 4 podocytopathies. In addition, from the middle period to the near end of the COVID-19 pandemic, we have seen two of the patients who developed nephrotic syndrome following COVID-19 vaccination. Three of 4 podocytopathies were collapsing glomerulopathy (also called collapsing focal segmental glomerulosclerosis) and the fourth was a minimal change disease (MCD). Two of three collapsing glomerulopathy were found in African American patients, one of who was tested positive for having the high-risk allele APOL-1 G1. In addition, the two renal biopsies showed either MCD or replaced MCD following COVID-19 vaccination. MCD can be a rare complication following COVID-19 infection and COVID-19 vaccination, raising the question if there are similar antigens induced by the infection or by the vaccination that trigger the MCD. This article reports our experience of diagnosing podocytopathies related to either COVID-19 infection or its vaccination and provides a literature review regarding the incidence and potential pathophysiology in the field.

CMV-associated collapsing focal segmental glomerulosclerosis after kidney transplant in a pediatric patient

BACKGROUND

Cytomegalovirus (CMV) is a significant cause of morbidity among immunocompromised patients who have undergone kidney transplantation and is known to rarely induce collapsing focal segmental glomerulosclerosis (FSGS) among adults.

METHODS

We present the first reported case of CMV-induced collapsing FSGS in a pediatric patient after kidney transplant.

RESULTS

Our patient underwent a deceased donor kidney transplant due to end-stage renal disease secondary to lupus nephritis. Approximately 4 months after transplantation, he developed signs of worsening kidney function in the setting of CMV viremia and was found to have collapsing features of FSGS on kidney transplant biopsy. He was managed with a prompt escalation of antiviral therapy along with a reduction of immunosuppression and recovered without significant complication. At follow-up, he continued to have undetectable CMV titers, creatinine within normal limits, and no significant proteinuria.

CONCLUSION

This report demonstrates CMV as a cause of collapsing FSGS and should be considered among pediatric transplant recipients who present with acute kidney injury, as should early assessment of APOL1 genetic status in both donor and recipient.

Collapsing Focal Segmental Glomerulosclerosis After Kidney Transplantation: Is It a Consequence of Viral Infections?

BACKGROUND

The aim of this case study was to explore the possible link between viral infections and collapsing focal segmental glomerulosclerosis (cFSGS) in patients who underwent kidney transplantation.

METHODS

This case study included 3 case reports of patients who underwent kidney transplantation. The case reports were presented clinically and pathohistologically with cFsGS as a possible consequence of viral infections.

RESULTS

The first patient developed cFSGS after polymerase chain reaction for SARS-CoV2 was positive twice. He gradually developed terminal stage chronic kidney disease. The second patient developed cFSGS with high range proteinuria after cytomegalovirus infection, which has been treated with 3 lines of antiviral medicaments. The third patient developed cFSGS as a possible consequence of hepatitis B virus infection.

CONCLUSIONS

This case study highlighted the importance of viral etiology in the pathway of cFSGS. Pathogenic links between viral infections and concomitant glomerulopathies are challenging, especially in immunocompromised transplanted patients.

Role of progenitor cell marker CD133 in supporting diagnosis of collapsing glomerulopathy

Purpose

A previous immunofluorescent study suggests that, in collapsing glomerulopathy, most hyperplastic podocytes that stained positively for a progenitor cell marker CD133 are derived from CD133 + parietal epithelial cells. In pathology practice, not all renal biopsies with collapsing glomerulopathy show the typical morphologic features for this entity, which include florid podocyte hyperplasia, collapsing glomerular capillary loops, and cystic tubular dilation. This study was made to determine if CD133 staining using an immunohistochemical method can be used to confirm hyperplastic podocytes and identify extensive acute tubular injury in collapsing glomerulopathy.

Methods

Twenty-one collapsing glomerulopathy biopsies were stained for CD133 and compared with 15 biopsies with focal segmental glomerulosclerosis, not otherwise specified (FSGS).

Results

All patients with collapsing glomerulopathy were of African American descent with prominent renal failure and nephrotic range proteinuria. In contrast, the FSGS group consisted of patients from a variety of ethnic backgrounds with nephrotic range proteinuria but relatively low serum creatinine. The striking finding was that all collapsing glomerulopathy cases showed positive CD133 staining in the clusters of hyperplastic podocytes. There was significantly higher CD133-positive staining rate for hyperplastic podocytes (38%) in the glomeruli of the collapsing glomerulopathy group when compared to small clusters of hyperplastic podocytes in the FSGS group (8%). In addition, when compared to the relatively weak CD133 staining in the proximal tubules of the FSGS group, the proximal tubules of the collapsing glomerulopathy group all showed diffuse and strong CD133 staining as a feature of severe acute tubular injury, which corresponded to the high serum creatinine levels in these patients.

Conclusion

Our data indicate that the combination of the distinctive mosaic CD133 staining in hyperplastic podocytes and the diffuse tubular CD133 staining is helpful in supporting a diagnosis of collapsing glomerulopathy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11255-021-03078-0.

Cytomegalovirus-Associated Nephrotic Syndrome in a Patient with Myasthenia Gravis Treated with Azathioprine: A Case Report

BACKGROUND Patients taking azathioprine (AZA) are very susceptible to development of cytomegalovirus (CMV) infection. The symptoms of CMV infection are varied. In some rare cases, CMV infection can even result in nephrotic syndrome. CASE REPORT Here, we present a rare case of nephrotic syndrome associated with CMV infection, induced by azathioprine intake. The patient, diagnosed with myasthenia gravis, was initially treated with azathioprine for 2 years. Then, the patient was admitted to the hospital due to nephrotic syndrome and acute kidney injury. Minimal change disease with acute tubular necrosis were diagnosed through biopsy. After an initial good response to hemodialysis and steroids, the patient developed severe pneumonia and oral ulcers. Further anti-CMV IHC staining of kidney tissues showed positive cells in tubules, indicating nephrotic syndrome secondary to CMV infection. CONCLUSIONS This case reminded us that CMV may be an under-recognized cause of nephrotic syndrome. Patients treated with azathioprine are very susceptible to developing CMV infection. During the diagnosis of nephrotic syndrome, we should always take CMV infection into consideration, especially in patients with on azathioprine.

Early diagnosis and successful treatment of cytomegalovirus peritonitis in children with primary nephrotic syndrome: case series and literature review

Cytomegalovirus (CMV) is a major pathogen in immunocompromised population and CMV infections in immunocompromised patients cause substantial morbidity and mortality. The common clinical manifestations of CMV infection are pneumonia, hepatitis, colitis and so on, while CMV peritonitis without gut perforation is rare. Reviewing the literature, CMV peritonitis in patients with nephrotic syndrome (NS) had not been reported. Only four cases of CMV peritonitis without gut perforation were reported in adults with other diseases. Two cases were diagnosed by reverse-transcription polymerase chain reaction (RT-PCR) of ascites while the other two cases by histopathological examination of peritoneal tissue. We report four cases of primary nephrotic syndrome complicated with CMV peritonitis. Four cases all diagnosed by RT-PCR of ascites (659–455 000 copies/mL). We mainly discusses the diagnosis and treatment of CMV peritonitis without gut perforation.

Extracellular vesicles mediate cellular interactions in renal diseases-Novel views of intercellular communications in the kidney

The kidney is a complicated and important internal organ receiving approximately 20% of the cardiac output and mediates numerous pathophysiologic actions. These include selectively filtering macromolecules of the blood, exquisite reclaimation of electrolyctes, urine concentration via an elegant osmotic mechanism, and excretion of an acid load. In addition, the renal tubules carry out secretory functions and produce hormones and cytokines. The kidney receives innervation and hormonal regulation. Therefore, dysfunction of the kidney leads to retention of metabolic waste products, and/or significant proteinuria and hematuria. In the past several decades, the role of extracellular vesicles (EVs) in intercellular communications, and the uptake of EVs by recipient cells through phagocytosis and endocytosis have been elucidated. The new knowledge on EVs expands over the classical mechanisms of cellular interaction, and may change our way of thinking of renal pathophysiology in the subcellular scale. Based on some ultrastructural discoveries in the kidney, this review will focus on the role of EVs in intercellular communications, their internalization by recipient cells, and their relationship to renal pathology.

Focal segmental glomerulosclerosis associated with acute cytomegalovirus infection in a renal transplant

Focal segmental glomerulosclerosis (FSGS) occurring in association with cytomegalovirus (CMV) infection in a renal transplant patient with no previous history of FSGS has rarely been reported. We present a case of a 16-year-old renal transplant recipient who developed acute hepatitis, leukopenia, nephrotic syndrome, and progressive renal dysfunction in the setting of acute infection with CMV. The cytomegalovirus infection was successfully treated with IV ganciclovir followed by oral valganciclovir but renal function deterioration and massive proteinuria continued. Features of FSGS were found on two renal allograft biopsies. Plasmapheresis and cyclophosphamide treatment was instituted with no clear effect on disease progress.

Expanding the spectrum of APOL1-related renal disease: de novo collapsing glomerulopathy following kidney transplant

Santoriello et al. report a series of 38 cases of de novo collapsing glomerulopathy following kidney transplant. Associations included acute rejection, viral infection, and APOL1 high-risk genotype (the latter in 9 cases). Risk factors for collapsing glomerulopathy included acute rejection, viral infection, acute vaso-occlusive disease, and an African American donor. The data are suggestive of, but do not directly establish, a role for interferon in these associations.