Multicenter Clinicopathologic Correlation of Kidney Biopsies Performed in COVID-19 Patients Presenting With Acute Kidney Injury or Proteinuria

Incidence, pathophysiology, risk factors, histopathology, and outcomes of COVID-19-induced acute kidney injury: A narrative review

The COVID-19 pandemic, caused by the SARS-CoV-2 virus, has led to a significant burden on global healthcare systems. COVID-19-induced acute kidney injury (AKI) is among one of the complications, that has emerged as a critical and frequent condition in COVID-19 patients. This AKI among COVID-19 patients is associated with poor outcomes, and high mortality rates, especially in those with severe AKI or requiring renal replacement therapy. COVID-19-induced AKI represents a significant complication with complex pathophysiology and multifactorial risk factors. Indeed, several pathophysiological mechanisms, including direct viral invasion of renal cells, systemic inflammation, endothelial and thrombotic abnormalities as well as nephrotoxic drugs and rhabdomyolysis are believed to underlie this condition. Moreover, histopathological and immunohistopathological findings commonly observed in postmortem studies include acute tubular necrosis, glomerular injury, and the presence of viral particles within renal tissue and urine. Identified risk factors for developing AKI vary among studies, depending on regions, underlying conditions, and the severity of the disease. Moreover, histopathological and immunohistopathological findings commonly observed in postmortem studies include show acute tubular necrosis, glomerular injury, and viral particles within renal tissue and urine. While, identified risk factors for developing AKI vary among studies, according to regions, underlying conditions, and the gravity of the disease. This narrative review aims to synthesize current knowledge on the incidence, pathophysiology, risk factors, histopathology, and outcomes of AKI induced by COVID-19.

Podocyte-Specific Protein Expression in Urine Exosome Acts as a Marker for Renal Injury in Post-COVID State

Introduction: Severe acute respiratory syndrome Coronavirus-2 (SARS-CoV-2) has been associated with the development of COVID-19. COVID-19 may cause endothelial cell dysfunction (ECD), which can lead to cardiometabolic diseases and podocytopathy. In this study, we explored whether presence of hyperglycemia predisposes to SARS-CoV-2 infection, in vitro, and whether COVID-19 can put an individual at a higher risk of persistent renal damage in the long-term following acute COVID infection. To estimate renal damage, we evaluated albuminuria and podocytopathy. Podocytopathy was estimated by measuring podocyte-specific protein levels in urine-derived exosomes from patients who were admitted with acute COVID-19 at 10 days, 6 months, and 12 months post-acute SARS-CoV-2 infection. Methods: Blood and urine samples from patients with SARS-CoV-2 post-infection were procured from the George Washington University COVID repository. Peripheral blood mononuclear cells and urine exosomes were isolated. Podocyte-specific proteins Podocalyxin (PODXL) and Nephrin (NEPH) were identified from urine exosomes. Results: Urine exosomal podocalyxin levels were significantly high at 10 week (n = 18; P = 0.001), 6 month (n = 25; P = 0.003) and 12 month (n = 14; P = 0.0001) time points. Nephrin levels were also noted to be high at 10 week (n = 18; P = 0.001) and 12 month (n = 14; P = 0.007) time points, compared with urine samples obtained from type 2 diabetes subjects who never had COVID-19. Though urinary podocyte-specific proteins were high, compared to control, there were no significant differences noted on urine albumin:creatinine ratios (UACR) between the groups. Conclusion: Persistent high levels of podocyte-specific proteins noted in urinary exosomes even at 12 months post-Covid may lead to the development of chronic kidney disease.

Anti-glomerular basement membrane disease superimposed on membranous nephropathy after coronavirus disease 2019: A case report

Membranous nephropathy concurrent with anti-glomerular basement membrane disease is rarely reported. Acute kidney injury is prominent when these diseases coexist. Coronavirus disease 2019 may trigger this superimposition. Herein, we report the case of a 60-year-old woman with pathologically confirmed anti-phospholipase A2 receptor-associated membranous nephropathy. She experienced complete remission of membranous nephropathy after non-immunosuppressive treatment. One month before admission, she experienced fever and her coronavirus disease 2019 antigen test was positive. She developed gross hematuria, progressively worsening fatigue, and poor appetite, even after the coronavirus disease 2019 antigen test returned negative. Her urinalysis showed positive proteinuria and hematuria. Her serum creatinine levels increased rapidly. Her anti-phospholipase A2 receptor antibody was borderline positive. Anti-glomerular basement membrane disease was diagnosed with high anti-glomerular basement membrane antibody titer. She responded well to corticosteroids, cyclophosphamide, and plasmapheresis. We further reviewed several cases of concurrent anti-glomerular basement membrane disease and membranous nephropathy. Phospholipase A2 receptor positivity was not rare in these patients, and their renal outcome was not optimistic. Thus, when the clinical manifestation changes in patients with pathologically confirmed glomerular disease, superimposition on other disease should be considered.

Influence of Baseline Kidney Function on Patient and Kidney Outcomes in Patients with COVID-19: A Multi-National Observational Study

Background/Objectives: Acute kidney injury (AKI) is a common complication of coronavirus disease-19 (COVID-19), but the impact of baseline kidney function and care processes on outcomes is not well understood. We hypothesized that baseline kidney health status may influence courses and outcomes of AKI. Methods: This is a multinational, multicenter, retrospective cohort study. We included hospitalized adult COVID-19 patients with kidney disease (AKI, end-stage kidney disease (ESKD), chronic kidney disease (CKD), or kidney transplant (KT) recipients) from 1 January 2020 to 31 March 2022, across 52 centers in 23 countries. Patients with no prior kidney function information were classified as acute kidney disease (AKD) if estimated glomerular filtration rate (eGFR) at admission was <60 mL/min/1.73 m2 and as no known kidney disease (NKD) if eGFR was ≥60 mL/min/1.73 m2. We defined combined outcome as death or non-kidney recovery at hospital discharge. Multivariable binary regression models were applied. Results: Among 4158 patients, 882 had ESKD, and 3038 developed AKI. AKI patients were categorized as NKD (31.8%), AKD (38.6%), CKD (23.3%), and KT recipients (3.3%). NKD patients had higher AKI severity and more intensive care unit care needs. In the multivariable analyses, the risk of the combined outcome was higher in AKD (OR 1.459 [1.061, 2.005]) or CKD (OR 1.705 [1.206, 2.410]) patients, although the risk of in-hospital mortality was similar to NKD. Among the survivors at hospital discharge, the risk of partial or non-recovery was higher in CKD (OR 5.445 [3.864, 7.672]) or KT recipients (OR 4.208 [2.383, 7.429]) compared to NKD. These findings were consistent across income categories. Conclusions: Among AKI patients with COVID-19, nearly two-thirds had underlying kidney dysfunction, with 55% identified as having baseline AKD, which had higher risk of death or non-kidney recovery at discharge compared to NKD.

A guide to studying 3D genome structure and dynamics in the kidney

The human genome is tightly packed into the 3D environment of the cell nucleus. Rapidly evolving and sophisticated methods of mapping 3D genome architecture have shed light on fundamental principles of genome organization and gene regulation. The genome is physically organized on different scales, from individual genes to entire chromosomes. Nuclear landmarks such as the nuclear envelope and nucleoli have important roles in compartmentalizing the genome within the nucleus. Genome activity (for example, gene transcription) is also functionally partitioned within this 3D organization. Rather than being static, the 3D organization of the genome is tightly regulated over various time scales. These dynamic changes in genome structure over time represent the fourth dimension of the genome. Innovative methods have been used to map the dynamic regulation of genome structure during important cellular processes including organism development, responses to stimuli, cell division and senescence. Furthermore, disruptions to the 4D genome have been linked to various diseases, including of the kidney. As tools and approaches to studying the 4D genome become more readily available, future studies that apply these methods to study kidney biology will provide insights into kidney function in health and disease.

A Case of Autoimmune Hemolytic Anemia Following COVID-19 Infection Accompanied by Acute Tubulointerstitial Nephritis in a Kidney Transplant Recipient

BACKGROUND

Acute tubular injury is one of the main causes of acute tubular injury (acute kidney injury ) in patients with COVID-19 infection. Autoimmune hemolytic anemia (AIHA) is also one of the autoimmune complications of COVID-19. However, AIHA accompanied by acute tubulointerstitial nephritis (ATIN) caused by SARS-CoV-2 is rarely reported. Here, we report a kidney transplant recipient who underwent graftectomy owing to ATIN accompanied by AIHA, possibly exacerbated by COVID-19 infection.

CASE PRESENTATION

A 32-year-old male renal allograft recipient owing to immunoglobulin A nephropathy visited the emergency department owing to dyspnea and general weakness. Three weeks earlier, the patient had been transplanted with deceased-donor kidney with full HLA-A, -B, -DR match, and had been on tacrolimus, prednisolone, and mycophenolate since then. At the time of the visit, laboratory findings revealed hemoglobin of 2.4 g/dL, reticulocyte of 21.7%, total bilirubin of 1.9 mg/dL, direct bilirubin of 0.3 mg/dL, lactate dehydrogenase of 946 U/L, haptoglobin of <10 mg/dL, and severe red cell agglutination on peripheral blood smear, which suggested AIHA. In addition, his SARS-CoV-2 real-time polymerase chain reaction test was positive. During steroid treatment for AIHA, a sudden decrease in urine volume, estimated glomerular filtration rate (from 64.9 to 35.1 mL/min/1.73 m2) and increase of creatinine (from 1.42 to 2.36 mg/dL) indicated renal function deterioration, so steroid was increased to 500 mg. On the third day of renal function deterioration, dialysis was started owing to anuria and fluid retention. On renal biopsy, C4d was absent; however, ATIN with eosinophilic infiltration was observed. On renal ultrasound examination, a severely enlarged kidney with edema was observed. At the same time, the patient had a high fever with increased C-reactive protein and procalcitonin. Graftectomy was performed to prevent secondary infection. The postgraftectomy renal biopsy showed renal parenchymal and hilar inflammatory change, endotheliitis, and lymphocytic infiltration of peripheral nerve fibers. After graftectomy, dialysis was maintained and AIHA had ameliorated.

CONCLUSION

The patient had to have his allografted kidney removed owing to ATIN possibly caused by COVID-19 infection. Acute kidney injury caused by SARS-CoV-2 can be either by direct viral infection or as consequence of immunological response. The exact immunological mechanism of AIHA secondary to COVID-19 infection remains to be elucidated.

ACE2 and TMPRSS2 in human kidney tissue and urine extracellular vesicles with age, sex, and COVID-19

SARS-CoV-2 virus infects cells by engaging with ACE2 requiring protease TMPRSS2. ACE2 is highly expressed in kidneys. Predictors for severe disease are high age and male sex. We hypothesized that ACE2 and TMPRSS2 proteins are more abundant (1) in males and with increasing age in kidney and (2) in urine and extracellular vesicles (EVs) from male patients with COVID-19 and (3) SARS-CoV-2 is present in urine and EVs during infection. Kidney cortex samples from patients subjected to cancer nephrectomy (male/female; < 50 years/˃75 years, n = 24; ˃80 years, n = 15) were analyzed for ACE2 and TMPRSS2 protein levels. Urine from patients hospitalized with SARS-CoV-2 infection was analyzed for ACE2 and TMPRSS2. uEVs were used for immunoblotting and SARS-CoV-2 mRNA and antigen detection. Tissue ACE2 and TMPRSS2 protein levels did not change with age. ACE2 was not more abundant in male kidneys in any age group. ACE2 protein was associated with proximal tubule apical membranes in cortex. TMPRSS2 was observed predominantly in the medulla. ACE2 was elevated significantly in uEVs and urine from patients with COVID-19 with no sex difference compared with urine from controls w/wo albuminuria. TMPRSS2 was elevated in uEVs from males compared to female. ACE2 and TMPRSS2 did not co-localize in uEVs/apical membranes. SARS-CoV-2 nucleoprotein and mRNA were not detected in urine. Higher kidney ACE2 protein abundance is unlikely to explain higher susceptibility to SARS-CoV-2 infection in males. Kidney tubular cells appear not highly susceptible to SARS-CoV-2 infection. Loss of ACE2 into urine in COVID could impact susceptibility and angiotensin metabolism.

Kidney damage associated with COVID-19: from the acute to the chronic phase

Severe acute respiratory syndrome coronavirus-2 (SARS-COV-2) infection is well established as a systemic disease including kidney damage. The entry point into the renal cell remains the angiotensin-converting enzyme 2 (ACE-2) receptor and the spectrum of renal lesions is broad, with a clear predominance of structural and functional tubular lesions. The most common form of glomerular injury is collapsing glomerulopathy (CG), which is strongly associated with apolipoprotein L1(APOL-1) risk variants. These acute lesions, which are secondary to the direct or indirect effects of SARS-CoV-2, can progress to chronicity and are specific to long COVID-19 in the absence of any other cause. Residual inflammation associated with SARS-CoV-2 infection, in addition to acute kidney injury (AKI) as a transitional state with or without severe histological lesions, may be responsible for greater kidney function decline in mild-to-moderate COVID-19. This review discusses the evidence for renal histological markers of chronicity in COVID-19 patients and triggers of low-grade inflammation that may explain the decline in kidney function in the post-COVID-19 period.

SARS-CoV-2 infection causes a decline in renal megalin expression and affects vitamin D metabolism in the kidney of K18-hACE2 mice

Patients with coronavirus disease 2019 (COVID-19) often experience acute kidney injury, linked to disease severity or mortality, along with renal tubular dysfunction and megalin loss in proximal tubules. Megalin plays a crucial role in kidney vitamin D metabolism. However, the impact of megalin loss on vitamin D metabolism during COVID-19 is unclear. This study investigated whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection reduces megalin expression in proximal tubules and its subsequent effect on vitamin D metabolism in mice expressing human angiotensin converting enzyme 2 (K18-hACE2 mice). Histological and immunohistochemical staining analyses revealed glomerular and capillary congestion, and elevated renal neutrophil gelatinase-associated lipocalin levels, indicative of acute kidney injury in K18-hACE2 mice. In SARS-CoV-2-infected mice, immunohistochemical staining revealed suppressed megalin protein levels. Decreased vitamin D receptor (VDR) localization in the nucleus and increased mRNA expression of VDR, CYP27B1, and CYP24A1 were observed by quantitative PCR in SARS-CoV-2-infected mice. Serum vitamin D levels remained similar in infected and vehicle-treated mice, but an increase in tumor necrosis factor-alpha and a decrease in IL-4 mRNA expression were observed in the kidneys of the SARS-CoV-2 group. These findings suggest that megalin loss in SARS-CoV-2 infection may impact the local role of vitamin D in kidney immunomodulation, even when blood vitamin D levels remain unchanged.

Nephrotic Syndrome Throughout Childhood: Diagnosing Podocytopathies From the Womb to the Dorm

The etiologies of podocyte dysfunction that lead to pediatric nephrotic syndrome (NS) are vast and vary with age at presentation. The discovery of numerous novel genetic podocytopathies and the evolution of diagnostic technologies has transformed the investigation of steroid-resistant NS while simultaneously promoting the replacement of traditional morphology-based disease classifications with a mechanistic approach. Podocytopathies associated with primary and secondary steroid-resistant NS manifest as diffuse mesangial sclerosis, minimal change disease, focal segmental glomerulosclerosis, and collapsing glomerulopathy. Molecular testing, once an ancillary option, has become a vital component of the clinical investigation and when paired with kidney biopsy findings, provides data that can optimize treatment and prognosis. This review focuses on the causes including selected monogenic defects, clinical phenotypes, histopathologic findings, and age-appropriate differential diagnoses of nephrotic syndrome in the pediatric population with an emphasis on podocytopathies.

The interplay of COVID-19 and HIV: A comprehensive review of clinical outcomes and demographic associations

AIM

The COVID-19 pandemic posed unprecedented challenges to global healthcare, particularly affecting respiratory systems and impacting individuals with pre-existing conditions, including those with HIV.

METHOD

HIV's impact on clinical outcomes was assessed in four Statistical Population, synchronized with control groups. The study also explored the influence of SARS-CoV-2 and COVID-19 treatments. Ultimately, a comparison was drawn between patients with and without HIV.

RESULTS

In the first Statistical Population of COVID-19 patients with HIV, predominantly African-American men with risk factors such as obesity, hypertension, and diabetes were present. Diagnostic results showed no significant differences between the two groups. In the second Statistical Population, half of the patients were asymptomatic, with diagnoses mostly based on clinical symptoms; 6 individuals developed severe respiratory illness. In the third Statistical Population, 81 % of patients were treated at home, and all hospitalized patients had CD4+ lymphocyte counts above 350 cells/mm³. Most patients improved, with fatalities attributed to comorbid conditions. In the fourth Statistical Population, HIV patients were less likely to benefit from antimicrobial drugs, and mortality was higher, though synchronized analysis did not reveal significant differences.

CONCLUSION

HIV patients are more susceptible to COVID-19, but the direct impact is less significant than other factors. Additional factors contribute to increased risk, while early improvement, accurate diagnosis, and intensive care reduce fatalities.

Serological responses and clinical outcomes following a three-dose primary COVID-19 vaccine schedule in kidney transplant recipients and people on dialysis

Objectives

Despite vaccination strategies, people with chronic kidney disease, particularly kidney transplant recipients (KTRs), remained at high risk of poor COVID-19 outcomes. We assessed serological responses to the three-dose COVID-19 vaccine schedule in KTRs and people on dialysis, as well as seroresponse predictors and the relationship between responses and breakthrough infection.

Methods

Plasma from 30 KTRs and 17 people receiving dialysis was tested for anti-Spike receptor binding domain (RBD) IgG and neutralising antibodies (NAb) to the ancestral and Omicron BA.2 variant after Doses 2 and 3 of vaccination.

Results

After three doses, KTRs achieved lower anti-Spike RBD IgG levels (P < 0.001) and NAb titres than people receiving dialysis (P = 0.002). Seropositive cross-reactive Omicron neutralisation levels were achieved in 11/27 (40.7%) KTRs and 11/14 (78.6%) dialysis recipients. ChAdOx1/viral-vector vaccine type, higher mycophenolate dose (> 1 g per day) and lower absolute B-cell counts predicted poor serological responses in KTRs. ChAdOx-1 vaccine type and higher monocyte counts were negative predictors in dialysis recipients. Among ancestral NAb seroresponders, higher NAb levels positively correlated with higher Omicron neutralisation (R = 0.9, P < 0.001). More KTRs contracted SARS-CoV-2 infection (14/30; 47%) than dialysis recipients (5/17; 29%) and had more severe disease. Those with breakthrough infections had significantly lower median interdose incremental change in anti-Spike RBD IgG and ancestral NAb titres.

Conclusion

Serological responses to COVID-19 vaccines in KTRs lag behind their dialysis counterparts. KTRs remained at high risk of breakthrough infection after their primary vaccination schedule underlining their need for booster doses, strict infection prevention measures and close surveillance.

The Time-Varying Impact of COVID-19 on the Acute Kidney Disorders: A Historical Matched Cohort Study and Mendelian Randomization Analysis

Background: This study aimed to explore the time-varying impact of COVID-19 on acute kidney disorders, including acute kidney injury and other acute kidney diseases. Methods: From the UK Biobank, 10,121 participants with COVID-19 were matched with up to 3 historically unexposed controls by age, sex, Townsend deprivation index, and the status of hospitalization or receiving critical care. We investigated the association between COVID-19 and incidence of acute kidney disorders, within the first 4 weeks after infection, using conditional and time-varying Cox proportional hazard regression. In addition, one-sample Mendelian randomization, utilizing the polygenic risk score for COVID-19 as an instrumental variable, was conducted to explore the potential causality of the association. Results: In the matched cohort study, we observed a significant association between COVID-19 and acute kidney disorders predominantly within the first 3 weeks. The impact of COVID-19 was time dependent, peaking in the second week (hazard ratio, 12.77; 95% confidence interval, 5.93 to 27.70) and decreasing by the fourth week (hazard ratio, 2.28; 95% confidence interval, 0.75 to 6.93). In subgroup analyses, only moderate to severe COVID-19 cases were associated with acute worsening of renal function in a time-dependent pattern. One-sample Mendelian randomization analyses further showed that COVID-19 might exert a "short-term" causal effect on the risk of acute kidney disorders, primarily confined to the first week after infection. Conclusions: The risk of acute kidney disorders following COVID-19 demonstrates a time-varying pattern. Hazard effects were observed only in patients with moderate or severe but not mild COVID-19.

An Update on Viral Infection-Associated Collapsing Glomerulopathy

The COVID-19 era has been a reminder to clinicians around the world of the important role that viral infections play in promoting glomerular disease. Several viral infections including human immunodeficiency virus (HIV), severe acute respiratory syndrome coronavirus 2, Epstein-Barr virus, cytomegalovirus, and parvovirus B19 can cause podocyte injury and present with a collapsing glomerulopathy (CG) variant of focal segmental glomerulosclerosis or minimal change disease. CG associated with COVID-19 has been termed COVID-19-associated nephropathy due to its striking resemblance to HIV-associated nephropathy. Host susceptibility is a major determinant of viral infection-associated CG, and the presence of two APOL1 risk variants explains most of the racial predilection to viral-associated CG observed in individuals of African ancestry. Interactions between APOL1 risk variants, viral genes, and the systemic inflammatory response to viral infection all contribute to kidney injury. This review will summarize our current knowledge of viral infection-associated CG, focusing primarily on the clinical presentation, histological features, mechanisms, and disease course of HIV-associated nephropathy and COVID-19-associated nephropathy.

Collapsing Glomerulopathy

Collapsing glomerulopathy (CG) is a pattern of kidney injury characterized by segmental or global collapse of the glomerular tuft associated with overlying epithelial cell hyperplasia. Although CG may be idiopathic, a wide range of etiologies have been identified that can lead to this pattern of injury. Recent advances have highlighted the role of inflammatory and interferon signaling pathways and upregulation of apolipoprotein L1 (APOL1) within podocytes in those carrying a high-risk APOL1 genotype. In this review, we describe the etiology, pathogenesis, pathology, and clinical course of CG, focusing on nonviral etiologies. We also describe current treatments and explore potential therapeutic options targeting interferon/APOL1 pathways in CG.

An unprecedented global challenge, emerging trends and innovations in the fight against COVID-19: A comprehensive review

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a highly contagious and dangerous virus that caused the global COVID-19 pandemic in early 2020. It primarily affects the respiratory system, leading to severe illness and high rates of mortality worldwide. The virus enters the body by binding to a receptor called ACE2, which is present in specific cells of the lungs known as type 2 alveolar epithelial cells. Numerous studies have investigated the consequences of SARS-CoV-2 infection, revealing various impacts on the body. This review provides an overview of SARS-CoV-2, including its structure and how it infects cells. It also examines the different variants of concern, such as Alpha, Beta, Gamma, Delta, and the more recent Omicron variant, discussing their characteristics and the level of damage they cause. The usage of drugs to treat COVID-19 is another aspect that has been covered and compares the effectiveness and use of antiviral drugs in the treatment and its potential benefits in COVID-19 treatment. Furthermore, this review explores the consequences and abnormalities associated with SARS-CoV-2 infection, including its impact on various organs and systems in the body. And also discussing the different COVID-19 vaccines available and their effectiveness in preventing infection and reducing the severity of illness. The current review ensures the recent update of the COVID research with expert's knowledge, collection of numerous data from reliable sources and methodologies as well as update of findings based on reviews. This review also provided clear contextual explanations to aid the interpretation and application of the results. The main motto and limitation of this manuscript are to address the computational methods of drug discovery against the rapidly evolving SARS-CoV-2 virus, which has been discussed. Additionally, current computational approaches which are cost effective and can able to predict the therapeutic agents for the treatment against the virus have also been discussed.

Minimal Change Disease Associated with SARS-CoV-2 (COVID-19) Infection among Adult Filipinos: A Report of Two Cases and Review of Related Literature

A 40-year-old Filipino female with a history of right total mastectomy for a low-grade phyllodes tumor was admitted due to stillbirth. Her laboratory results revealed an incidental finding of a positive COVID-19 RT-PCR swab, serum creatinine 1.04 mg/dL, urine RBC 1/HPF, and a 24-hour urine protein of 9.22 grams with hypoalbuminemia and dyslipidemia. Serologic workup was noted to be negative. A kidney biopsy was performed which demonstrated unremarkable light microscopy (LM) and immunofluorescence (IF) with widespread podocyte-foot process effacement, consistent with minimal change disease. She was started on prednisone (1 mg/kg/day) and achieved complete remission after six weeks. A 61-year-old Filipino male with a history of Type 2 Diabetes Mellitus, Hypertension, Dyslipidemia, and mild COVID-19 infection four months prior, now presented with diarrhea. On admission, his COVID-19 RT-PCR swab revealed a reinfection. Workup demonstrated a serum creatinine 3.39 mg/dL, urine RBC 2/HPF, and urine ACR 2.6 g/g. Serologic tests were negative. He was diagnosed with Nephrotic Syndrome and underwent kidney biopsy. Findings showed an unremarkable LM and IF with widespread podocyte-foot process effacement, consistent with minimal change disease. He was started on prednisone (1 mg/kg/day) and achieved complete remission after eight weeks. SARS-CoV-2 (COVID-19) may present with a variety of kidney involvement which includes glomerulopathies such as MCD. An accurate diagnosis using the patient's clinical presentation, renal histopathology, and adjunct laboratory examinations, is essential to direct effective management and good outcomes.

The relation between proteinuria and the severity of COVID-19

BACKGROUND

The association between proteinuria, which is also an indicator of chronic kidney disease (CKD), and coronavirus disease 2019 (COVID-19) severity is unclear.

METHODS

We selected 342 hospitalized patients with COVID-19 diagnosed via polymerase chain reaction testing between February 2020 and October 2022 and who had at least one urinalysis 14-365 days before admission.

RESULTS

Proteinuria before admission was associated neither with oxygen administration nor developing pneumonia in multivariate analysis (odds ratio [OR] 1.03; 95% confidence interval (CI) 0.44-2.40, p = 0.95 and OR 1.01; 95% CI 0.47-2.17, p = 0.98, respectively). Proteinuria on admission was associated both with oxygen administration and developing pneumonia in multivariate analysis (OR 3.29; 95% CI 1.37-7.88, p < 0.01 and OR 3.81; 95% CI 1.68-8.62, p < 0.01, respectively). The percentage of patients with proteinuria on admission was significantly higher than those before admission (37.4% vs. 17.8%; p < 0.01). In the subgroup analysis, proteinuria on admission among patients with eGFR ≥ 60 mL/min/1.73 m2 was associated with both oxygen administration and developing pneumonia (OR 4.86; 95% CI 1.22-19.38, p = 0.03, OR 3.65; 95% CI 1.06-12.58, p = 0.04, respectively). In contrast, proteinuria on admission among patients with eGFR < 60 mL/min/1.73 m2 was associated with developing pneumonia (OR 6.45; 95%CI 1.78-23.35, p = 0.01), not with oxygen administration (OR 3.28; 95% CI 0.92-11.72, p = 0.07).

CONCLUSIONS

Although underlying proteinuria before admission was not associated with COVID-19 severity, proteinuria on admission was associated with oxygen demand and developing pneumonia.

Multi-omics Approach in Kidney Transplant: Lessons Learned from COVID-19 Pandemic

Purpose of Review

Multi-omics approach has advanced our knowledge on transplantation-associated clinical outcomes, such as acute rejection and infection, and emerging omics data are becoming available in kidney transplant and COVID-19. Herein, we discuss updated findings of multi-omics data on kidney transplant outcomes, as well as COVID-19 and kidney transplant.

Recent Findings

Transcriptomics, proteomics, and metabolomics revealed various inflammation pathways associated with kidney transplantation-related outcomes and COVID-19. Although multi-omics data on kidney transplant and COVID-19 is limited, activation of innate immune pathways and suppression of adaptive immune pathways were observed in the active phase of COVID-19 in kidney transplant recipients.

Summary

Multi-omics analysis has led us to a deeper exploration and a more comprehensive understanding of key biological pathways in complex clinical settings, such as kidney transplantation and COVID-19. Future multi-omics analysis leveraging multi-center biobank collaborative will further advance our knowledge on the precise immunological responses to allograft and emerging pathogens.

Coronavirus disease 2019-associated thrombotic microangiopathy treated with plasma exchange and antihypertensive therapy in a patient with HIV: A case report with literature review

RATIONALE

Coronavirus disease 2019 (COVID-19) is an infectious disease that often causes complications in multiple organs and thrombosis due to abnormal blood coagulation. This case report aimed to describe the clinical course of COVID-19-associated thrombotic microangiopathy (TMA) and reviewed the comprehensive information on TMA, thrombotic thrombocytopenic purpura (TTP), and atypical hemolytic uremic syndrome associated with COVID-19 in the past literature.

PATIENT CONCERNS

A 46-year-old Japanese man was diagnosed with human immunodeficiency virus infection 10 years ago and treated with antiretroviral therapy. The patient presented with fever, malaise, hematuria, and bilateral upper abdominal discomfort for the past 4 days.

DIAGNOSES

COVID-19-associated TMA was diagnosed based on a positive polymerase chain reaction for severe acute respiratory syndrome coronavirus 2 and laboratory findings such as thrombocytopenia, acute kidney injury, and hemolytic anemia. Malignant hypertension and human immunodeficiency virus infection were also considered as differential diagnoses of TMA.

INTERVENTIONS

Considering the possibility of TTP, plasma exchange was performed, and glucocorticoids were administered. Hemodialysis was performed for acute kidney injury. Antihypertensive drugs were administered to control the high blood pressure.

OUTCOMES

Platelet count and renal function improved, and hemodialysis was no longer required. The patient was in good general condition and was discharged from the hospital.

LESSONS

COVID-19-associated TMA should be considered as a differential diagnosis during the COVID-19 epidemic. Excessive inflammation and severe COVID-19 are not essential for TMA development. Early intervention using conventional TMA treatments, such as plasma exchange and corticosteroids, might be important in improving prognosis while differentiating between TTP and atypical hemolytic uremic syndrome. Antihypertensive therapy may be helpful in the treatment of COVID-19-associated TMA.

Sustained Response to Eculizumab in a Patient With COVID-19-Associated Acute Thrombotic Microangiopathy of the Allograft Kidney: A Case Report

Acute thrombotic microangiopathy (TMA) developing in association with SARS-CoV-2 infection is a rare but recognized phenomenon in native kidneys. In the allograft kidney, a diagnosis of TMA has a broad etiologic differential, including antibody-mediated rejection and recurrent and de novo causes of TMA that affect the native kidney. Prior case reports have described plasma exchange or eculizumab use in patients with COVID-19-associated TMA. Herein, we describe the course of a kidney transplant patient with COVID-19-associated TMA with response to eculizumab that was sustained after medication withdrawal and review the literature on COVID-19-associated TMA of the allograft kidney.

Kidney complications associated with COVID-19 infection and vaccination in children and adolescents: a brief review

Coronavirus disease 2019 (COVID-19) has spread considerably across the globe, affecting numerous children and adolescents besides adults. Despite its relatively lower incidence rates in children and adolescents than in adults, some infected children and adolescents exhibit a severe postinflammatory response known as multisystem inflammatory syndrome in children, followed by acute kidney injury, a common complication. Meanwhile, few reports have been available regarding kidney complications such as idiopathic nephrotic syndrome and other glomerulopathies associated with COVID-19 infection and vaccination in children and adolescents. However, the morbidity and mortality of these complications are not exceptionally high; more importantly, causality has yet to be clearly established. Finally, vaccine hesitancy in these age groups should be addressed, considering the strong evidence of COVID-19 vaccine safety and efficacy.

COVID and the Kidney: An Update

Coronavirus disease-2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2, has led to a global pandemic that continues to be responsible for ongoing health issues for people worldwide. Immunocompromised individuals such as kidney transplant recipients and dialysis patients have been and continue to be among the most affected, with poorer outcomes after infection, impaired response to COVID-19 vaccines, and protracted infection. The pandemic also has had a significant impact on patients with underlying chronic kidney disease (CKD), with CKD increasing susceptibility to COVID-19, risk of hospital admission, and mortality. COVID-19 also has been shown to lead to acute kidney injury (AKI) through both direct and indirect mechanisms. The incidence of COVID-19 AKI has been decreasing as the pandemic has evolved, but continues to be associated with adverse patient outcomes correlating with the severity of AKI. There is also increasing evidence examining the longer-term effect of COVID-19 on the kidney demonstrating continued decline in kidney function several months after infection. This review summarizes the current evidence examining the impact of COVID-19 on the kidney, covering both the impact on patients with CKD, including patients receiving kidney replacement therapy, in addition to discussing COVID-19 AKI.

Inhibition of Toll-like receptor 4 and Interleukin-1 receptor prevent SARS-CoV-2 mediated kidney injury

Acute kidney injury (AKI) is a common and severe complication of the coronavirus disease 2019 (COVID-19). Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) directly affects the glomerular and tubular epithelial cells to induce AKI; however, its pathophysiology remains unclear. Here, we explored the underlying mechanisms and therapeutic targets of renal involvement in COVID-19. We developed an in vitro human kidney cellular model, including immortalized tubular epithelial and endothelial cell lines, demonstrating that SARS-CoV-2 directly triggers cell death. To identify the molecular targets in the process of SARS-CoV-2-mediated cell injury, we performed transcriptional analysis using RNA sequencing. Tubular epithelial cells were more prone to dying by SARS-CoV-2 than endothelial cells; however, SARS-CoV-2 did not replicate in renal cells, distinct from VeroE6/transmembrane protease serine 2 cells. Transcriptomic analysis revealed increased inflammatory and immune-related gene expression levels in renal cells incubated with SARS-CoV-2. Toll-like receptor (TLR) 3 in renal cells recognized viral RNA and underwent cell death. Furthermore, analysis of upstream regulators identified several key transcriptional regulators. Among them, inhibition of the interleukin-1 receptor (IL-1R) and TLR4 pathways protects tubular epithelial and endothelial cells from injury via regulation of the signal transducer and activator of transcription protein-3/nuclear factor-kB pathway. Our results reveal that SARS-CoV-2 directly injures renal cells via the proinflammatory response without viral replication, and that IL-1R and TLR4 may be used as therapeutic targets for SARS-CoV-2 mediated kidney injury.

Acute and chronic histopathological findings in renal biopsies in COVID-19

The dominant ICU admission diagnosis of COVID-19 patients is respiratory insufficiency, but 32-57% of hospitalized COVID-19 patients develop acute kidney injury (COVID-AKI). The renal histopathological changes accompanying COVID-AKI are not yet fully described. To obtain a detailed insight into renal histopathological features of COVID-19, we conducted a review including all studies reporting histopathological findings of diagnostic and postmortem kidney biopsies from patients with COVID-19 published between January 1, 2020, and January 31, 2021. A total of 89 diagnostic and 194 postmortem renal biopsies from individual patients in 39 published studies were investigated and were included in the analysis. In the diagnostic biopsy group, mean age was 56 years and AKI incidence was 96%. In the postmortem biopsy group, mean age was 69 years and AKI incidence was 80%. In the diagnostic biopsy group, the prevalence of acute glomerular diseases was 74%. The most common glomerular lesions were collapsing focal segmental glomerulosclerosis (c-FSGS) in 54% and thrombotic microangiopathy (TMA) in 9% of patients. TMA was also found in 10% of patients in the postmortem biopsy group. The most common acute tubular lesions was acute tubular necrosis (ATN) which was present in 87% of patients in the diagnostic and in 77% of patients in the postmortem biopsy group. Additionally, we observed a high prevalence of preexisting chronic lesions in both groups such as atherosclerosis and glomerulosclerosis. Histopathological changes in renal biopsies of COVID-19 patients show a heterogeneous picture with acute glomerular lesions, predominantly c-FSGS and TMA, and acute tubular lesions, predominantly ATN. In many patients, these lesions were present on a background of chronic renal injury.

Post-acute sequelae of COVID-19: understanding and addressing the burden of multisystem manifestations

Individuals with SARS-CoV-2 infection can develop symptoms that persist well beyond the acute phase of COVID-19 or emerge after the acute phase, lasting for weeks or months after the initial acute illness. The post-acute sequelae of COVID-19, which include physical, cognitive, and mental health impairments, are known collectively as long COVID or post-COVID-19 condition. The substantial burden of this multisystem condition is felt at individual, health-care system, and socioeconomic levels, on an unprecedented scale. Survivors of COVID-19-related critical illness are at risk of the well known sequelae of acute respiratory distress syndrome, sepsis, and chronic critical illness, and these multidimensional morbidities might be difficult to differentiate from the specific effects of SARS-CoV-2 and COVID-19. We provide an overview of the manifestations of post-COVID-19 condition after critical illness in adults. We explore the effects on various organ systems, describe potential pathophysiological mechanisms, and consider the challenges of providing clinical care and support for survivors of critical illness with multisystem manifestations. Research is needed to reduce the incidence of post-acute sequelae of COVID-19-related critical illness and to optimise therapeutic and rehabilitative care and support for patients.

Management of immunosuppressive therapy in kidney transplant recipients with COVID-19. A multicentre national study derived from the Spanish Society of Nephrology COVID registry

INTRODUCTION

SARS CoV2 infection has had a major impact on renal transplant patients with a high mortality in the first months of the pandemic. Intentional reduction of immunosuppressive therapy has been postulated as one of the cornerstone in the management of the infection in the absence of targeted antiviral treatment. This has been modified according to the patient`s clinical situation and its effect on renal function or anti-HLA antibodies in the medium term has not been evaluated.

OBJECTIVES

Evaluate the management of immunosuppressive therapy made during SARS-CoV2 infection, as well as renal function and anti-HLA antibodies in kidney transplant patients 6 months after COVID19 diagnosis.

MATERIAL AND METHODS

Retrospective, national multicentre, retrospective study (30 centres) of kidney transplant recipients with COVID19 from 01/02/20 to 31/12/20. Clinical variables were collected from medical records and included in an anonymised database. SPSS statistical software was used for data analysis.

RESULTS

renal transplant recipients with COVID19 were included (62.6% male), with a mean age of 57.5 years. The predominant immunosuppressive treatment prior to COVID19 was triple therapy with prednisone, tacrolimus and mycophenolic acid (54.6%) followed by m-TOR inhibitor regimens (18.6%). After diagnosis of infection, mycophenolic acid was discontinued in 73.8% of patients, m-TOR inhibitor in 41.4%, tacrolimus in 10.5% and cyclosporin A in 10%. In turn, 26.9% received dexamethasone and 50.9% were started on or had their baseline prednisone dose increased. Mean creatinine before diagnosis of COVID19, at diagnosis and at 6 months was: 1.7 ± 0.8, 2.1 ± 1.2 and 1.8 ± 1 mg/dl respectively (p < 0.001). 56.9% of the patients (N = 350) were monitored for anti-HLA antibodies. 94% (N = 329) had no anti-HLA changes, while 6% (N = 21) had positive anti-HLA antibodies. Among the patients with donor-specific antibodies post-COVID19 (N = 9), 7 patients (3.1%) had one immunosuppressant discontinued (5 patients had mycophenolic acid and 2 had tacrolimus), 1 patient had both immunosuppressants discontinued (3.4%) and 1 patient had no change in immunosuppression (1.1%), these differences were not significant.

CONCLUSIONS

The management of immunosuppressive therapy after diagnosis of COVID19 was primarily based on discontinuation of mycophenolic acid with very discrete reductions or discontinuations of calcineurin inhibitors. This immunosuppression management did not influence renal function or changes in anti-HLA antibodies 6 months after diagnosis.

The Prediction Score of Acute Kidney Injury in Patients with Severe COVID-19 Infection

BACKGROUND

The incidence and risk factors for acute kidney injury in COVID-19 patients vary across studies, and predicting models for AKI are limited. This study aimed to identify the risk factors for AKI in severe COVID-19 infection and develop a predictive model for AKI.

METHOD

Data were collected from patients admitted to the ICU at Thammasat University Hospital in Thailand with PCR-confirmed COVID-19 between 1 January 2021, and 30 June 2022.

RESULTS

Among the 215 severe-COVID-19-infected patients, 102 (47.4%) experienced AKI. Of these, 45 (44.1%), 29 (28.4%), and 28 (27.4%) patients were classified as AKI stage 1, 2, and 3, respectively. AKI was associated with 30-day mortality. Multivariate logistic regression analysis revealed that prior diuretic use (odds ratio [OR] 7.87, 95% confidence interval [CI] 1.98-31.3; p = 0.003), use of a mechanical ventilator (MV) (OR 5.34, 95%CI 1.76-16.18; p = 0.003), and an APACHE II score ≥ 12 (OR 1.14, 95%CI 1.05-1.24; p = 0.002) were independent risk factors for AKI. A predictive model for AKI demonstrated good performance (AUROC 0.814, 95%CI 0.757-0.870).

CONCLUSIONS

Our study identified risk factors for AKI in severe COVID-19 infection, including prior diuretic use, an APACHE II score ≥ 12, and the use of a MV. The predictive tool exhibited good performance for predicting AKI.

Kidney Allograft Rejection and Coronavirus Disease 2019 Infection: A Narrative Review

The world has experienced a global medical and socioeconomic burden following the coronavirus disease 2019 (COVID-19) pandemic. COVID-19 is a systemic disease and may affect different organs including the kidneys. Current literature contains reports on COVID-19-related conditions such as acute kidney injury, and complications experienced by chronic kidney disease, end stage kidney disease, and kidney transplant patients. Here, we discuss the incidence of kidney allograft rejection, immunosuppression management and rejection risk, donor-specific antibodies and previous rejection episodes, and rejection outcomes in kidney transplant recipients with COVID-19 by reviewing current studies.

Exacerbation of Intimal Fibrosis and Endarteritis in a Kidney Transplant Recipient with Chronic Active Antibody-Mediated Rejection and COVID-19: A Case Report

Kidney transplant recipients are immunocompromised hosts at risk for comorbidity and mortality due to infection. Currently, there are no established guidelines for the management of immunosuppressed transplant recipients with coronavirus disease 2019 (COVID-19). The impact of COVID-19 and its therapeutic management on chronic active antibody-mediated rejection (CAAMR) are still unclear. Here, we report a case of CAAMR exacerbation with endarteritis and intimal fibrosis after COVID-19. A 41-year-old female kidney transplant recipient with CAAMR was admitted to a local hospital with moderately severe COVID-19. Her doses of tacrolimus and mycophenolate mofetil were reduced, and she was administered methylprednisolone pulse and antiviral drugs. This resulted in a good clinical course and she was discharged in 15 days. During and after hospitalization, the immunosuppressants were gradually returned to the baseline levels. However, about 1.5 months after discharge, the serum creatinine level became elevated. An indication kidney biopsy showed CAAMR with intimal fibrosis and endarteritis in all interlobular arteries. An increase of immunosuppressant led to a decrease of the serum creatinine level. Factors contributing to CAAMR with intimal fibrosis and endarteritis may include (1) insufficient immunosuppression due to changes in the levels of immunosuppressive; (2) overlap with endothelial cell injury caused by COVID-19, and (3) an immune-activated state associated with COVID-19. COVID-19 is a life-threatening disease that can result in unexpected changes in immunological status. Possible allograft rejection should be carefully managed in such patients.

Severe Acute Respiratory Syndrome Coronavirus 2 Vasculopathy in a Syrian Golden Hamster Model

Clinical evidence of vascular dysfunction and hypercoagulability as well as pulmonary vascular damage and microthrombosis are frequently reported in severe cases of human coronavirus disease 2019 (COVID-19). Syrian golden hamsters recapitulate histopathologic pulmonary vascular lesions reported in patients with COVID-19. Herein, special staining techniques and transmission electron microscopy further define vascular pathologies in a Syrian golden hamster model of human COVID-19. The results show that regions of active pulmonary inflammation in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are characterized by ultrastructural evidence of endothelial damage with platelet marginalization and both perivascular and subendothelial macrophage infiltration. SARS-CoV-2 antigen/RNA was not detectable within affected blood vessels. Taken together, these findings suggest that the prominent microscopic vascular lesions in SARS-CoV-2-inoculated hamsters likely occur due to endothelial damage followed by platelet and macrophage infiltration.

Tubulointerstitial nephritis and uveitis in children during the COVID-19 pandemic: report of four cases

Tubulointerstitial nephritis and uveitis (TINU) is a rare autoimmune disorder often triggered by drugs and infections. Since the onset of the COVID-19 pandemic, we have observed an unusual cluster of paediatric cases. Four children (3 females) were diagnosed with TINU (median age 13 years) following a kidney biopsy and ophthalmologic assessment. Presenting symptoms included abdominal pain (3 cases), fatigue, weight loss and vomiting (2 cases). At presentation, median eGFR was 50.3 ml/min/1.73m2 (range 19.2-69.3). Anaemia was common (3 cases) with median haemoglobin of 10.45 g/dL (range 8.4-12.1). Two patients were hypokalaemic and 3 had non-hyperglycaemic glycosuria. Median urine protein:creatinine ratio was 117 mg/mmol (range 68-167). SARS-CoV-2 antibodies were detected in 3 cases at presentation. All were asymptomatic for COVID-19 with a negative PCR. Kidney function improved following high-dose steroids. However, disease relapse was observed during steroid tapering (2 cases) and upon discontinuation (2 cases). All patients responded well to further high dose steroids. Mycophenolate mofetil was introduced as a steroid-sparing agent. At latest follow up (range 11-16 months), median eGFR was 109.8 ml/min/1.73m2. All four patients continue on mycophenolate mofetil, with 2 patients applying topical steroids for uveitis. Our data suggest that SARS-CoV-2 infection might be a trigger for TINU.

Complement-Mediated Thrombotic Microangiopathy Related to COVID-19 or SARS-CoV-2 Vaccination

Introduction

Infectious diseases and vaccinations are trigger factors for thrombotic microangiopathy. Consequently, the COVID-19 pandemic could have an effect on disease manifestation or relapse in patients with atypical hemolytic syndrome/complement-mediated thrombotic microangiopathy (aHUS/cTMA).

Methods

We employed the Vienna TMA cohort database to examine the incidence of COVID-19 related and of SARS-CoV-2 vaccination-related relapse of aHUS/cTMA among patients previously diagnosed with aHUS/cTMA during the first 2.5 years of the COVID-19 pandemic. We calculated incidence rates, including respective confidence intervals (CIs) and used Cox proportional hazard models for comparison of aHUS/cTMA episodes following infection or vaccination.

Results

Among 27 patients with aHUS/cTMA, 13 infections triggered 3 (23%) TMA episodes, whereas 70 vaccinations triggered 1 TMA episode (1%; odds ratio 0.04; 95% CI 0.003-0.37, P = 0.01). In total, the incidence of TMA after COVID-19 or SARS-CoV-2 vaccination was 6 cases per 100 patient years (95% CI 0.017-0.164) (4.5/100 patient years for COVID-19 and 1.5/100 patient years for SARS-CoV-2 vaccination). The mean follow-up time was 2.31 ± 0.26 years (total amount: 22,118 days; 62.5 years) to either the end of the follow-up or TMA relapse (outcome). Between 2012 and 2022 we did not find a significant increase in the incidence of aHUS/cTMA.

Conclusion

COVID-19 is associated with a higher risk for aHUS/cTMA recurrence when compared to SARS-CoV-2 vaccination. Overall, the incidence of aHUS/cTMA after COVID-19 infection or SARS-CoV-2 vaccination is low and comparable to that described in the literature.

Risk Factors and Clinical Characteristics of Acute Kidney Injury in Patients with COVID-19: A Systematic Review and Meta-Analysis

Acute kidney injury (AKI) is associated with a worse prognosis in coronavirus disease 2019 (COVID-19) patients. Identification of AKI, particularly in COVID-19 patients, is important for improving patients' management. The study aims to assess risk factors and comorbidities of AKI in COVID-19 patients. We systematically searched PubMed and DOAJ databases for relevant studies involving confirmed COVID-19 patients with data on risk factors and comorbidities of AKI. The risk factors and comorbidities were compared between AKI and non-AKI patients. A total of 30 studies involving 22385 confirmed COVID-19 patients were included. Male (OR: 1.74 (1.47, 2.05)), diabetes (OR: 1.65 (1.54, 1.76)), hypertension (OR: 1.82 (1.12, 2.95)), ischemic cardiac disease (OR: 1.70 (1.48, 1.95)), heart failure (OR: 2.29 (2.01, 2.59)), chronic kidney disease (CKD) (OR: 3.24 (2.20, 4.79)), chronic obstructive pulmonary disease (COPD) (OR: 1.86 (1.35, 2.57)), peripheral vascular disease (OR: 2.34 (1.20, 4.56)), and history of nonsteroidal anti-inflammatory drugs (NSAID) (OR: 1.59 (1.29, 1.98)) were independent risk factors associated with COVID-19 patients with AKI. Patients with AKI presented with proteinuria (OR: 3.31 (2.59, 4.23)), hematuria (OR: 3.25 (2.59, 4.08)), and invasive mechanical ventilation (OR: 13.88 (8.23, 23.40)). For COVID-19 patients, male gender, diabetes, hypertension, ischemic cardiac disease, heart failure, CKD, COPD, peripheral vascular disease, and history of use of NSAIDs are associated with a higher risk of AKI.

FSGS and COVID-19 in Non-African American Patients

Collapsing Focal Segmental Glomerulosclerosis (FSGS) has been reported relatively frequently in African American (AA) patients with coronavirus disease 2019 (COVID-19), and it is associated almost always with Apolipoprotein L gen 1 (APOL1) high-risk variants. We reviewed the published literature from April 2020 to November 2022 searching for non-African American (non-AA) patients with FSGS associated with COVID-19 (eight White patients, six Hispanic patients, three Asian patients, one Indian patient, and one Asian Indian patient). The following histologic patterns were found: collapsing (n=11), not otherwise specified (n=5), tip (n=2), and perihilar (n=1). Fifteen of the 19 patients had AKI. The APOL1 genotype was reported in only six of the 19 non-AA patients. Three of them (two Hispanic patients and one White patient) with collapsing FSGS had high-risk APOL1 variants. The other three patients (two White patients and one Hispanic patient with the collapsing variant, tip variant, and not otherwise specified) had low-risk APOL1 variants. Among 53 African American patients with collapsing FSGS associated with COVID-19, 48 had high-risk APOL1 variants and five had low-risk APOL1 variants. We conclude that in non-AA patients, FSGS is a rare complication of COVID-19. FSGS associated with COVID-19 can occur rarely with low-risk APOL1 variants in non-AA and AA patients. Non-AA patients reported to be associated with high-risk APOL1 variants possibly reflect inaccuracy of self-reported race with AA admixture because of unknown ancestry. Given the importance of APOL1 in the pathogenesis of FSGS associated with viral infection and to avoid racial bias, it seems appropriate that APOL1 testing be considered in patients with FSGS associated with COVID-19, regardless of self-reported race.

Collapsing glomerulopathy: unraveling varied pathogeneses

PURPOSE OF REVIEW

Collapsing glomerulopathy presents clinically with nephrotic syndrome and rapid progressive loss of kidney function. Animal models and patient studies have uncovered numerous clinical and genetic conditions associated with collapsing glomerulopathy, as well as putative mechanisms, which will be reviewed here.

RECENT FINDINGS

Collapsing glomerulopathy is classified pathologically as a variant of focal and segmental glomerulosclerosis (FSGS). As such, most research efforts have focused on the causative role of podocyte injury in driving the disease. However, studies have also shown that injury to the glomerular endothelium or interruption of the podocyte-glomerular endothelial cell signaling axis can also cause collapsing glomerulopathy. Furthermore, emerging technologies are now enabling exploration of diverse molecular pathways that can precipitate collapsing glomerulopathy using biopsies from patients with the disease.

SUMMARY

Since its original description in the 1980s, collapsing glomerulopathy has been the subject of intense study, and these efforts have uncovered numerous insights into potential disease mechanisms. Newer technologies will enable profiling of the intra-patient and inter-patient variability in collapsing glomerulopathy mechanisms directly in patient biopsies, which will improve the diagnosis and classification of collapsing glomerulopathy.

Kidney Biopsy Findings in Patients with SARS-CoV-2 Infection or After COVID-19 Vaccination

BACKGROUND

Emerging case series described a temporal association between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination and de novo or relapsing kidney diseases. We aimed to further understand vaccination- and coronavirus disease 2019 (COVID-19)-associated kidney diseases.

METHODS

We present findings from native kidney biopsies of patients recently vaccinated against SARS-CoV-2 ( n =27) and those with COVID-19 ( n =15), reviewed at a single German center. Diagnoses were compared among all native kidney biopsies ( n =10,206) obtained between the prepandemic (2019), pandemic (2020), and vaccination periods (2021) to determine whether there was an increase in kidney diseases in the observed periods.

RESULTS

Biopsy indication was increased serum creatinine and/or new-onset proteinuria. Glomerulopathies (20/27, 74%) were more common than tubulointerstitial diseases in postvaccination patients, with necrotizing GN (8/27, 30%) and primary podocytopathies and other GN types (6/27, 22% each) the most common forms. Acute tubular injury was the most common kidney disease in patients with COVID-19, followed by thrombotic microangiopathy (TMA) and necrotizing GN. The postvaccination and COVID-19 infection groups had similar kidney function recovery rates (69% and 73%, respectively). Furthermore, the frequencies of necrotizing GN, pauci-immune GN, TMA, or primary podocytopathies at our center did not increase between 2019 and 2021.

CONCLUSIONS

We observed differences in entity frequencies between the SARS-CoV-2 vaccination or COVID-19 groups, with glomerulopathies being more common in patients after vaccination and tubulointerstitial diseases in patients with COVID-19. Cases of TMA were observed only in the COVID-19 group. We detected no increase in the frequency of necrotizing GN, TMA, or podocytopathies between 2019 and 2021.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Kidney Histopathology After COVID-19 and SARS-CoV-2 Vaccination, NCT05043168.

PODCAST

This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/CJASN/2023_05_08_CJN0000000000000106.mp3.

Modified Banff Criteria in Assessing SARS-CoV-2-Associated Renal Pathology: An Autopsy Study

Introduction SARS-CoV-2 is an epitheliotropic viral agent with epithelial tropism. Although the clinical significance and severity of affection is the most pronounced in the respiratory system, other organs and systems are also infected and, hence affected, such as the central nervous system, gastrointestinal tract, cardiovascular, and urinary systems. Herein, we set out to evaluate the presence and degree of morphological changes within the renal parenchyma and its relation to disease outcome. Materials and methods A retrospective non-clinical approach was utilized for the means of the study. All patients with real-time reverse transcriptase-polymerase chain reaction proven infection, subject to an autopsy performed in a period of two calendar years, were included in the study. Kidney tissue histopathology samples were analyzed using a modified Banff criteria system for acute onset and chronic changes. The results were compared for statistical significance with overall patient survival from symptom onset to death. Furthermore, SARS-CoV-2 viral presence was evaluated in renal structures by means of immunohistochemistry. Results A total of 40 patients were included in the study. Immunohistochemistry showed viral presence within a myriad of renal structured - endothelial cells, tubular cells, and podocytes. Modified Banff criteria showed significant acute changes within the parenchyma, including endotheliitis, glomerulitis, mesangial matrix expansion, tubulitis, capillaritis, arteritis, thrombosis (including thrombotic microangiopathy in four patients), and hemorrhages. Individual cases also presented with signs of rhabdomyolysis - myoglobulin casts. Signs of chronic injury were also present in most patients. However, when calculated as scores, neither acute nor chronic changes showed a correlation with time from symptom onset to death. Conclusion The results of the present study show both viral presence and a myriad of induced changes in the contents of SARS-CoV-2 infection within the renal parenchyma. The lack of correlation with the degree of changes, when compared to survival, is an encouraging fact that the changes are unlikely to play a role in direct tanatogenesis while having the potential to manifest as chronic kidney disease in the future.

COVID-19 and glomerular diseases

COVID (Coronavirus disease)-19 is a systemic disease and the kidney is one of the target organs of infection. Kidney injury is common and can occur in up to 40% of patients. Several glomerular diseases have been reported in association with COVID-19. Some are likely related to COVID-19 whereas many are likely coincidental. Glomerular diseases that are frequently reported in COVID-19 and have a plausible mechanistic explanation, are likely to be related to COVID-19. On the other hand, glomerular diseases that are seldom reported and have no known plausible mechanism, are likely to be unrelated. Collapsing glomerulopathy (CG) is by far the most prevalent. Its association with COVID-19, resembling human immunodeficiency virus (HIV) and CG, led to the newly proposed term “COVID-19 associated nephropathy” or “COVAN”. High-risk APOL1 genotypes are the major risk factor in COVAN patients. Podocytopathy, membranous nephropathy, pauci-immune crescentic glomerulonephritis, and thrombotic microangiopathy are also reported. In kidney allografts, CG remains the most common glomerular pathology. Patients typically present with acute kidney injury (AKI) or abnormal urinary findings at the time of or shortly after COVID-19 diagnosis. Treatment of glomerular disease in COVID-19 patients is challenging. Providers should cautiously consider balancing risks and benefit of immunosuppression, particularly in patients with active diseases. Short-term outcomes vary but generally remain poor with high morbidity and mortality. Future study of long-term outcomes is needed to improve our understanding of glomerular disease associated with COVID-19.

A specific molecular signature in SARS-CoV-2-infected kidney biopsies

Acute kidney injury is one of the most important complications in patients with COVID-19 and is considered a negative prognostic factor with respect to patient survival. The occurrence of direct infection of the kidney by SARS-CoV-2, and its contribution to the renal deterioration process, remain controversial issues. By studying 32 renal biopsies from patients with COVID-19, we verified that the major pathological feature of COVID-19 is acute tubular injury (ATI). Using single-molecule fluorescence in situ hybridization, we showed that SARS-CoV-2 infected living renal cells and that infection, which paralleled renal angiotensin-converting enzyme 2 expression levels, was associated with increased death. Mechanistically, a transcriptomic analysis uncovered specific molecular signatures in SARS-CoV-2-infected kidneys as compared with healthy kidneys and non-COVID-19 ATI kidneys. On the other hand, we demonstrated that SARS-CoV-2 and hantavirus, 2 RNA viruses, activated different genetic networks despite triggering the same pathological lesions. Finally, we identified X-linked inhibitor of apoptosis-associated factor 1 as a critical target of SARS-CoV-2 infection. In conclusion, this study demonstrated that SARS-CoV-2 can directly infect living renal cells and identified specific druggable molecular targets that can potentially aid in the design of novel therapeutic strategies to preserve renal function in patients with COVID-19.

Urinary albumin-to-creatinine ratio and serum albumin are predictors of acute kidney injury in non-ventilated COVID-19 patients: a single-center prospective cohort study

PURPOSE

Acute kidney injury (AKI) is a frequent complication among COVID-19 patients in the intensive care unit, but it is less frequently investigated in general internal medicine wards. We aimed to examine the incidence, the predictors of AKI, and AKI-associated mortality in a prospective cohort of non-ventilated COVID-19 patients. We aimed to describe the natural history of AKI by describing trajectories of urinary markers of hemodynamic, glomerular, and tubular injury.

METHODS

141 COVID-19 patients were enrolled to the study. AKI was defined according to KDIGO guidelines. Urine and renal function parameters were followed twice a week. Multivariate logistic regression was used to determine the predictors of AKI and mortality. Trajectories of urinary markers were described by unadjusted linear mixed models.

RESULTS

19.7% patients developed AKI. According to multiple logistic regression, higher urinary albumin-to-creatinine ratio (OR 1.48, 95% CI 1.04-2.12/1 mg/mmol) and lower serum albumin (OR 0.86, 95% CI 0.77-0.94/1 g/L) were independent predictors of AKI. Mortality was 42.8% in the AKI and 8.8% in the group free from AKI (p < 0.0001). According to multiple logistic regression, older age, lower albumin, and AKI (OR 3.9, 95% CI 1.24-12.21) remained independent predictors of mortality. Urinary protein-to-creatinine trajectories were diverging with decreasing values in those without incident AKI.

CONCLUSION

We found high incidence of AKI and mortality among moderately severe, non-ventilated COVID-19 patients. Its development is predicted by higher albuminuria suggesting that the originally damaged renal structure may be more susceptible for virus-associated effects. No clear relationship was found with a prerenal mechanism, and the higher proteinuria during follow-up may point toward tubular damage.

Renal Allograft Cortical Necrosis in a COVID-19 Positive Patient

The incidence of acute kidney injury (AKI) has been reported to be higher in kidney transplant recipients infected with SARS-CoV-2 compared with the general population. Here, we report a case of cortical necrosis in the graft kidney due to COVID infection in a patient with stable graft function over the years. The patient was started on hemodialysis and treated with steroids, and anticoagulants for COVID infection. Later, he had gradual improvement in his graft function and became dialysis independent on follow up.

Evidence of SARS-CoV-2 infection in postmortem lung, kidney, and liver samples, revealing cellular targets involved in COVID-19 pathogenesis

There is an urgent need to understand severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-host interactions involved in virus spread and pathogenesis, which might contribute to the identification of new therapeutic targets. In this study, we investigated the presence of SARS-CoV-2 in postmortem lung, kidney, and liver samples of patients who died with coronavirus disease (COVID-19) and its relationship with host factors involved in virus spread and pathogenesis, using microscopy-based methods. The cases analyzed showed advanced stages of diffuse acute alveolar damage and fibrosis. We identified the SARS-CoV-2 nucleocapsid (NC) in a variety of cells, colocalizing with mitochondrial proteins, lipid droplets (LDs), and key host proteins that have been implicated in inflammation, tissue repair, and the SARS-CoV-2 life cycle (vimentin, NLRP3, fibronectin, LC3B, DDX3X, and PPARγ), pointing to vimentin and LDs as platforms involved not only in the viral life cycle but also in inflammation and pathogenesis. SARS-CoV-2 isolated from a patient´s nasal swab was grown in cell culture and used to infect hamsters. Target cells identified in human tissue samples included lung epithelial and endothelial cells; lipogenic fibroblast-like cells (FLCs) showing features of lipofibroblasts such as activated PPARγ signaling and LDs; lung FLCs expressing fibronectin and vimentin and macrophages, both with evidence of NLRP3- and IL1β-induced responses; regulatory cells expressing immune-checkpoint proteins involved in lung repair responses and contributing to inflammatory responses in the lung; CD34⁺ liver endothelial cells and hepatocytes expressing vimentin; renal interstitial cells; and the juxtaglomerular apparatus. This suggests that SARS-CoV-2 may directly interfere with critical lung, renal, and liver functions involved in COVID-19-pathogenesis.

Collapsing focal segmental glomerulosclerosis secondary to COVID-19: A systematic review and meta-analysis

The renal system manifestations of coronavirus disease-2019 have been documented extensively; however, scientific literature remains scarce regarding collapsing glomerulopathy hence the need for this investigation.

Methods

A comprehensive review was conducted covering a timeline from 1 January 2020 to 5 February 2022 without any restrictions. The data extraction was conducted independently, and articles were assessed for the risk of bias. Data analysis was conducted using Comprehensive Meta-Analysis version 3.3.070 and RevMan version 5.4 for pooled proportions and risk ratio (RR) between dialysis-dependent and independent treatment groups with a P-value less than 0.05 considered significant.

Results

A total of 38 studies were included in this review, including 74 (65.9%) males. The mean age was 54.2 years old. The most common symptoms reported were related to the respiratory system (59.6%, 95% CI: 50.4-68.2%) and hematuria (34.2%, 95% CI: 26.1-43.4). Antibiotics (25.9%, 95% CI: 12.9-45.3%) was the commonest management used. Proteinuria was the most reported laboratory finding at 89.5% (95% CI: 82.4-93.9%), while the commonest microscopic finding was acute tubular injury (77.2%, 95% CI: 68.6-84.0%). An increased risk of the presence of symptoms (P=0.005) and microscopic findings (P=0.0003) related to collapsing glomerulopathy in dialysis-dependent group was noted with increased management (P=0.01) used in this group for coronavirus disease-2019 infection.

Conclusion

The findings of this study portray the prognostic value of the variables (symptoms and microscopic findings, etc.) reported in the analysis. Hence this study serves as a foundation for future investigations that minimize the study's limitations to provide a more robust conclusion.

Two-Hit Kidney Allograft Injury by SARS-CoV-2

Coronavirus disease 2019 (COVID-19) has been associated with acute kidney injury in kidney transplant recipients by several mechanisms. The authors report a case of acute kidney allograft dysfunction in a 48-year-old patient who presented in the emergency room with anasarca and nephrotic syndrome close after mild COVID-19 and no other clinical condition. Histopathology of the allograft biopsy revealed two distinct and simultaneous kidney lesions, collapsing glomerulopathy and thrombotic microangiopathy. Renal function persistently deteriorated, and definitive dialysis was initiated. After excluding other plausible causes for the findings, this case strengthens the hypothesis that the kidney allograft is also a target of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

COVID-19 and Kidney Disease

COVID-19 can cause acute kidney injury and may cause or exacerbate chronic kidney diseases, including glomerular diseases. SARS-CoV-2 infection of kidney cells has been reported, but it remains unclear if viral infection of kidney cells causes disease. The most important causes of kidney injury in patients with COVID-19 include impaired renal perfusion and immune dysregulation. Chronic kidney disease, especially kidney failure with kidney replacement therapy and kidney transplant, is associated with markedly increased COVID-19 mortality. Persons with severe kidney disease have been excluded from most clinical trials of COVID-19 therapies, so therapeutic approaches must be extrapolated from studies of patients without kidney disease. Some medications used to treat COVID-19 should be avoided or used at reduced dosages in patients with severe kidney disease and in kidney transplant recipients. Additional research is needed to determine the optimal strategies to prevent and treat COVID-19 in patients with kidney disease.

Kidney Disease and Viral Infection in COVID-19: Why Are Kidney Organoid and Biopsy Studies Not in Agreement?

CONTEXT

The clinical course of coronavirus disease-19 (COVID-19) can be complicated by acute kidney injury and proteinuria. Kidney cells express receptors for SARS-CoV-2, the virus responsible for COVID-19. Direct infection of the kidney parenchyma by SARS-CoV-2 has been proposed as the cause of renal dysfunction in COVID-19. Subject of Review: Kidney organoids derived from human embryonic stem cells or induced pluripotent cells can be reproducibly infected by SARS-CoV-2 in vitro and used to study therapeutics. However, kidney biopsy studies of COVID-19 patients with renal dysfunction have shown no evidence of viral infection. Second Opinion: Kidney organoids are susceptible to SARS-CoV-2 infection, which is probably facilitated by their limited architectural complexity and maturation compared to the intact organ and by the in vitro culture conditions. Conversely, kidneys in COVID-19 patients appear resistant to infection and may be injured through indirect mechanisms mediated by the host response to the respiratory viral infection, genetic susceptibility to the immune response, physiological disturbances, and therapies. More studies are needed to better understand why kidney organoids are more susceptible than mature kidneys to SARS-CoV-2 infection and further characterize the mechanisms of kidney injury in COVID-19.

Diffuse proliferative glomerulonephritis in a patient with COVID-19 infection

COVID-19 primarily presents with respiratory involvement. Extrapulmonary manifestations as the sole manifestation also occur although rare. The kidney, being one of the organs with the greatest number of ACE receptors, is usually reported as part of multiorgan involvement. We report an early adolescent boy who presented with nephrotic-nephritic syndrome with severe kidney dysfunction from COVID-19 infection. He had low C3 and undetected antineutrophil cytoplasmic antibodies, antinuclear antibody and antistreptolysin O. Kidney biopsy revealed findings consistent with diffuse proliferative glomerulonephritis with a focal glomerular crescent formation and thin basement nephropathy. Due to the rapidly progressive deterioration of kidney function, he was given pulse methylprednisolone therapy followed by oral prednisone. Complete recovery was documented 12 weeks after the onset of post-infectious glomerulonephritis. The possible pathogenesis of glomerulonephritis in a patient with COVID-19, its differential diagnosis and treatment are discussed.

Renal biopsy in systemic infections: expect the unexpected

Infection-related glomerulonephritis is well recognized in patients with ongoing infections. It can be missed, however, if the infection is unusual or undetected. We present three cases where the renal biopsy findings prompted the identification or treatment of systemic infections.Case 1: A 84-year-old male presented with acute kidney injury (AKI) and IgA vasculitis on skin biopsy. A renal biopsy showed active glomerulonephritis with abundant neutrophils and predominantly mesangial immune complex deposits containing IgA. The findings prompted an infectious workup which was positive for COVID-19, suggesting exacerbation of IgA nephropathy by recent COVID-19 infection. Case 2: A 31-year-old female status post kidney transplant for granulomatosis with polyangiitis (GPA) had recent pregnancy with preterm delivery, disseminated herpes simplex virus (HSV) infection with HSV hepatitis, E. coli on urine culture, and AKI. A renal biopsy showed proliferative glomerulonephritis with subendothelial and mesangial immune complex deposits containing IgG and C3. The findings were most consistent with infection-related immune complex glomerulonephritis, most likely HSV-related. Case 3: A 78-year-old female presented with AKI, proteinuria, hematuria, and positive p-ANCA. Clinically, ANCA vasculitis was suspected, and renal biopsy did show focal, segmental, necrotizing glomerulonephritis. However, immunofluorescence and electron microscopy showed IgM-rich deposits in the mesangium. The unusual presentation prompted an infectious workup including a Bartonella antibody panel which showed very high titers, suggesting Bartonella endocarditis.Infection-related glomerulonephritis has a wide variety of presentations histologically and clinically. The three cases we present here emphasize the importance of recognizing these entities to help guide treatment and improve patient care.

Pathogenesis and histological changes of nephropathy associated with COVID-19

Coronavirus disease 2019 (COVID-19) can cause damage to multiple organ, not only to the lungs, but also to the kidneys. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can cause acute and chronic kidney disease through direct viral infection, indirect injury, and vaccination-related injury. Like lung injury, kidney injury is also an important aspect affecting the severity and prognosis of SARS-CoV-2. This article summarizes the pathogenesis, pathological manifestations, and clinical features of SARS-CoV-2 direct or indirect renal injury. Including direct injury, indirect injury, special comorbidities (receiving kidney transplantation and chronic kidney disease), and vaccine-related renal injury, and exploring the possible therapeutic effect of anti-SARS-CoV-2 therapy on renal injury. The purpose is to provide reference for understanding COVID-19-related renal injury, guiding clinical and pathological diagnosis and treatment, and evaluating prognosis.