Clinical and pathological findings of SARS-CoV-2 infection and concurrent IgA nephropathy: a case report

Incidence and pathological features of IgA nephropathy before and during the COVID-19 pandemic

IgA nephropathy (IgAN) imposes a substantial burden of illness and death. However, a systematic evaluation of the impact of the COVID-19 pandemic on the incidence and pathology of IgAN has yet to be performed. In this study, we analyzed kidney biopsy results from two medical institutions, covering the timeframe from January 2016 to May 2023. We conducted statistical analyses on various glomerular diseases according to their corresponding pathological diagnoses. Our objective was to compare the incidence of different glomerular diseases before and during the COVID-19 pandemic. The study focused on variations in the incidence of IgAN, and collected clinical and pathological data to assess pathological changes using the Oxford Classification (MEST-C). The findings revealed a significant increase in the incidence of IgAN during the COVID-19 pandemic, from 39.9% prior to the pandemic to 46.3% during it, representing a net increase of 6.4% (P < 0.001). Although clinical manifestations and laboratory indicators of disease activity in IgAN patients remained consistent over both periods, observable changes occurred in pathological features. Specifically, the proportions of M1 and E1 lesions according to the Oxford classification significantly increased during the pandemic, with odds ratios of 11.764 (95% CI 5.583-24.789, P < 0.001) and 1.718 (95% CI 1.114-2.649, P = 0.014), respectively. Our results indicate that the incidence of IgAN has risen during the COVID-19 pandemic, along with exacerbated renal damage and elevated proportions of M1 and E1 in the Oxford classification.

IgA Nephropathy Secondary to COVID-19 Infection - A Case Report

We present a case of a 73-year-old African American lady with COVID-19 infection who developed acute Kidney Injury (AKI) and significant proteinuria. Renal biopsy showed IgA nephropathy. Patient was eventually diagnosed with IgA nephropathy secondary to COVID Infection. This unique case highlights the complexity of renal involvement in COVID-19. Notably, the onset of IgA nephropathy in the patient occurred several weeks after her COVID-19 diagnosis, deviating from the typical synpharyngitic presentation. This article contributes to the growing body of evidence regarding renal complications associated with COVID-19 and highlights the need for vigilance in assessing and managing renal conditions in COVID-19 patients, especially when atypical presentations occur.

The impact of mild and moderate COVID-19 infection on the progression of kidney dysfunction in patients with IgA nephropathy

Background

Previous research indicates that coronavirus disease 2019 (COVID-19) infection may have a role in triggering immunoglobulin A (IgA) nephropathy. However, limited research has explored the clinical implications of COVID-19 infection in individuals already diagnosed with IgA nephropathy. This study aimed to determine whether COVID-19 infection independently affects the subsequent trajectory of kidney function in IgA nephropathy patients.

Methods

This was a single-center cohort study. The study included 199 patients diagnosed with IgA nephropathy. The COVID-19 infection status was determined using a combined method: a questionnaire and the Health Code application, both administered at the end of 2022 in northern China. Kidney function trajectory was assessed by the estimated glomerular filtration rate (eGFR), calculated based on serum creatinine levels measured during follow-up outpatient visits. The primary endpoint of interest was the eGFR trajectory.

Results

Out of the 199 participants, 75% (n = 181) reported a confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, determined through antigen or polymerase chain reaction tests, accounting for 79% (n = 143) of the infected patients. A significant majority (98%) experienced mild to moderate symptoms. Over a median follow-up period of 10.7 months post-COVID-19 infection, notable clinical events included gross hematuria in 30 patients (16.6%), which normalized within an average of 3 days. Additionally, a 2-fold increase in proteinuria or progression to the nephrotic range was observed in 10 individuals (5.5%). No cases of acute kidney injury were noted. COVID-19 exposure was associated with an absolute change in eGFR of 2.98 mL/min/1.73 m2 per month (95% confidence interval 0.46 to 5.50). However, in a fully adjusted model, the estimated changes in eGFR slope post-COVID-19 were -0.39 mL/min/1.73 m2 per month (95% confidence interval -0.83 to 0.06, P = .088) which included the possibility of no significant effect. Notably, a higher rate of kidney function decline was primarily observed in patients with a baseline eGFR <45 mL/min/1.73 m2 [-0.56 mL/min/1.73 m2 (-1.11 to -0.01), P = .048]. In the cohort, there were few instances of severe COVID-19 cases. The absence of long-term follow-up outcomes was observed.

Conclusions

Overall, mild to moderate COVID-19 infection does not appear to significantly exacerbate the subsequent decline in kidney function among IgA nephropathy patients, particularly in those with preserved baseline kidney function.

Clinical and pathological findings of IgA nephropathy following SARS-CoV-2 infection

The features of IgA nephropathy (IgAN) after SARS-CoV-2 infection have not been well characterized. In this study, we compared the clinical and pathological characteristics of patients with IgAN who had experienced SARS-CoV-2 infection to those who had not. We conducted a retrospective study that enrolled 38 patients with biopsy-proven IgAN following SARS-CoV-2 infection with 4 months (post-SARS-CoV-2 infection group) and 1154 patients with IgAN prior to the pandemic (pre-SARS-CoV-2 infection group). Among the SARS-CoV-2 group cases, 61% were females. The average duration from SARS-CoV-2 infection to renal biopsy was 78.6 days. Prior to SARS-CoV-2 infection, the patients had different presentations of nephropathy. One patient had isolated hematuria, two had isolated proteinuria, twenty presented with both hematuria and proteinuria, and one patient had elevated serum creatinine. Additionally, there were eight cases with uncertain nephropathy history, and six cases did not have a history of nephropathy. Following SARS-CoV-2 infection, five patients experienced gross hematuria, one case exhibited creatinine elevation, and five cases showed an increase in proteinuria. The group of patients infected with SARS-CoV-2 after the COVID-19 pandemic exhibited older age, higher hypertension ratio and lower eGFR values compared to the pre-SARS-CoV-2 infection group. As for pathological parameters, a higher proportion of patients in the post-SARS-CoV-2 infection group exhibited a higher percentage of sclerotic glomeruli and glomerular ischemic sclerosis. There were no significant differences observed between the two groups in terms of therapy involving steroids, immunosuppressants, or RAS inhibitors. IgA nephropathy patients who were infected with SARS-CoV-2 were generally older and experienced more severe kidney damage compared to those without SARS-CoV-2 infection.

Identifying functional subtypes of IgA nephropathy based on three machine learning algorithms and WGCNA

BACKGROUND

IgA nephropathy (IgAN) is one of the most common primary glomerulonephritis, which is a significant cause of renal failure. At present, the classification of IgAN is often limited to pathology, and its molecular mechanism has not been established. Therefore we aim to identify subtypes of IgAN at the molecular level and explore the heterogeneity of subtypes in terms of immune cell infiltration, functional level.

METHODS

Two microarray datasets (GSE116626 and GSE115857) were downloaded from GEO. Differential expression genes (DEGs) for IgAN were screened with limma. Three unsupervised clustering algorithms (hclust, PAM, and ConsensusClusterPlus) were combined to develop a single-sample subtype random forest classifier (SSRC). Functional subtypes of IgAN were defined based on functional analysis and current IgAN findings. Then the correlation between IgAN subtypes and clinical features such as eGFR and proteinuria was evaluated by using Pearson method. Subsequently, subtype heterogeneity was verified by subtype-specific modules identification based on weighted gene co-expression network analysis(WGCNA) and immune cell infiltration analysis based on CIBERSORT algorithm.

RESULTS

We identified 102 DEGs as marker genes for IgAN and three functional subtypes namely: viral-hormonal, bacterial-immune and mixed type. We screened seventeen genes specific to viral hormonal type (ATF3, JUN and FOS etc.), and seven genes specific to bacterial immune type (LIF, C19orf51 and SLPI etc.). The subtype-specific genes showed significantly high correlation with proteinuria and eGFR. The WGCNA modules were in keeping with functions of the IgAN subtypes where the MEcyan module was specific to the viral-hormonal type and the MElightgreen module was specific to the bacterial-immune type. The results of immune cell infiltration revealed subtype-specific cell heterogeneity which included significant differences in T follicular helper cells, resting NK cells between viral-hormone type and control group; significant differences in eosinophils, monocytes, macrophages, mast cells and other cells between bacterial-immune type and control.

CONCLUSION

In this study, we identified three functional subtypes of IgAN for the first time and specific expressed genes for each subtype. Then we constructed a subtype classifier and classify IgAN patients into specific subtypes, which may be benefit for the precise treatment of IgAN patients in future.

Autoimmunity and Infection in Glomerular Disease

The ongoing glomerular damage of infections is not limited to the most widely known form of post-streptococcal glomerulonephritis, which is today less common in the Western world; other forms of glomerulonephritis are associated with several bacterial, viral and parasitic pathogens. The mechanisms responsible range from the direct damage of glomerular cells to the formation and deposition of immunocomplexes to molecular mimicry to the secretion of superantigens. Similarly, in the course of glomerular disease, infections are more frequent than in the general population due to the loss of immunoglobulins in urine and the immunosuppressive agents used to treat the autoimmune disease that decrease the activity of the immune system. Recognizing this two-way link, understanding its pathogenetic mechanism, and identifying the most appropriate therapeutic choice are essential for the personalized management of patients. In this continuously developing field, this short review summarizes the current state of the art as support for physicians, who are increasingly involved in managing patients with glomerular disease and infections.

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.

SARS-CoV-2 infection: a possible trigger for the recurrence of IgA nephropathy after kidney transplantation?

Immunoglobulin A nephropathy, the most common primary glomerulonephritis worldwide, is a leading cause of chronic kidney disease and end-stage kidney failure. Several cases of immunoglobulin A nephropathy relapse in native kidneys have been described after COVID-19 vaccination or SARS-CoV-2 infection. Here, we report the case of a 52-year-old kidney transplant recipient who had a stable transplant function for more than 14 years, with a glomerular filtration rate above 30 ml/min/1.73 m². The patient had been vaccinated against COVID-19 four times with the Pfizer-BioNTech vaccine, most recently in March 2022. Eight weeks after a symptomatic SARS-CoV-2 infection in June 2022, his glomerular filtration rate had decreased by more than 50%, and his proteinuria increased to 17.5 g per day. A renal biopsy indicated highly active immunoglobulin A nephritis. Despite steroid therapy, the function of the transplanted kidney deteriorated, and long-term dialysis became necessary because of recurrence of his underlying renal disease. This case report provides what is, to our knowledge, the first description of recurrent immunoglobulin A nephropathy in a kidney transplant recipient after SARS-CoV-2 infection leading to severe transplant failure and finally graft loss.

Secondary IgA Nephropathy and IgA-Associated Nephropathy: A Systematic Review of Case Reports

Primary (pIgAN), secondary IgA nephropathy (sIgAN), and IgA-associated nephropathy can be distinguished. While pIgAN has been thoroughly studied, information about the etiology of sIgAN remains scarce. As concerns sIgAN, several studies suggest that different etiologic factors play a role and ultimately lead to a pathophysiologic process similar to that of pIgAN. In this article, we review a vast number of cases in order to determine the novel putative underlying diseases of sIgAN. Moreover, updates on the common pathophysiology of primary disorders and sIgAN are presented. We identified liver, gastrointestinal, oncological, dermatological, autoimmune, and respiratory diseases, as well as infectious, iatrogenic, and environmental factors, as triggers of sIgAN. As novel biological therapies for listed underlying diseases emerge, we suggest implementing drug-induced sIgAN as a new significant category. Clinicians should acknowledge the possibility of sIgAN progression in patients treated with TNF-α inhibitors, IL-12/IL-23-inhibitors, immune checkpoint inhibitors, CTLA-4, oral anticoagulants, thioureylene derivatives, and anti-vascular endothelial growth factor drugs.

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.

Gross Hematuria Following SARS-CoV-2 Infection in IgA Nephropathy: A Report of 5 Cases

Gross hematuria after upper respiratory tract infections is a well-known characteristic symptom of immunoglobulin A nephropathy (IgAN). In recent years, there have been several reports of existing or newly diagnosed patients with IgAN susceptible to gross hematuria after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. However, reports of patients with IgAN and gross hematuria after SARS-CoV-2 infection are extremely rare despite a considerable number of patients with coronavirus disease 2019 (COVID-19) who preferentially present with upper respiratory symptoms. Here, we report the cases of 5 Japanese patients with IgAN who developed gross hematuria associated with SARS-CoV-2 infection. These patients presented with fever and other COVID-19-related symptoms, followed by the appearance of gross hematuria within 2 days, which lasted for 1-7 days. Acute kidney injury occurred after gross hematuria in 1 case. In all cases, microhematuria was identified before gross hematuria associated with SARS-CoV-2 infection, and it persisted after the gross hematuria episode. Because repeated gross hematuria and persistent microhematuria may lead to irreversible kidney injury, the clinical manifestations of patients with IgAN during the COVID-19 pandemic should be carefully monitored.

Adult-Onset IgA Vasculitis Associated With Pulmonary-Renal Syndrome Following COVID-19 Infection: A Case Report and Literature Review

Immunoglobulin A (IgA) vasculitis, also known as Henoch-Schönlein purpura (HSP), is an immune complex-mediated inflammation of small blood vessels that leads to tissue destruction with or without organ damage. We described a case of a 41-year-old otherwise healthy female who presented with an ascending rash distributed on both lower extremities and arthralgia. Blood testing revealed high blood urea nitrogen (BUN), creatinine, and inflammatory markers, as well as a negative autoimmune panel. Urinalysis revealed proteinuria and hematuria. A kidney biopsy was performed, which revealed abnormalities. She was started on intravenous (IV) methylprednisolone pulse therapy. Suddenly, she complained of epistaxis and became desaturated. Computed tomography revealed bilateral pleural effusion, and she was transferred to the ICU. Bronchoalveolar lavage was performed and was consistent with an increasing bloodier return. Plasma exchange was performed. The rash and clinical symptoms improved dramatically. This study reports a case of IgA vasculitis based on The European Alliance of Associations for Rheumatology/Pediatric Rheumatology International Trials Organization/Pediatric Rheumatology European Society (EULAR/PRINTO/PRES) criteria associated with pulmonary-renal syndrome following a case of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

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.

Kidney injury associated with COVID-19 infection and vaccine: A narrative review

The respiratory tract is the main infection site for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), resulting in many admissions to intensive care centers in several countries. However, in addition to lung involvement, kidney injury caused by the novel coronavirus has proven to be a significant factor related to high morbidity and mortality, alarming experts worldwide. The number of deaths has drastically reduced with the advent of large-scale immunization, highlighting the importance of vaccination as the best way to combat the pandemic. Despite the undeniable efficacy of the vaccine, the renal side effects associated with its use deserve to be highlighted, especially the emergence or reactivation of glomerulopathies mentioned in some case reports. This study aimed to identify the main renal morphological findings correlated with COVID-19 infection and its vaccination, seeking to understand the pathophysiological mechanisms, main clinical features, and outcomes.

Do we miss rare adverse events induced by COVID-19 vaccination?

Although severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has caused many complications, the invention of coronavirus disease 2019 (COVID-19) vaccines has also brought about several adverse events, from common side effects to unexpected and rare ones. Common vaccine-related adverse reactions manifest locally or systematically following any vaccine, including COVID-19 vaccines. Specific side effects, known as adverse events of particular interest (AESI), are unusual and need more evaluation. Here, we discuss some of the most critical rare adverse events of COVID-19 vaccines.

Coronavirus disease 2019, vaccination against coronavirus and immunoglobulin A-mediated diseases: systematic literature review

Coronavirus disease 2019 (COVID-19) and vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been associated with autoimmune phenomena. However, the interplay between COVID-19 or vaccination against SARS-CoV-2 and Berger glomerulonephritis or Henoch-Schönlein vasculitis, two diseases mediated by immunoglobulin A, has never been comprehensively investigated. Therefore, we carried out a systematic review of the literature on this topic. Following databases were used: Google Scholar, Excerpta Medica and the United States National Library of Medicine. Eighty-seven patients with immunoglobulin A-mediated diseases associated with SARS-CoV-2 infection or vaccination against coronavirus were sorted out (53% males, 47% females; 34 17-51 years of age, median and interquartile range): 47 cases of Berger glomerulonephritis and 40 of Henoch-Schönlein vasculitis. Approximately 50% (N = 24) of Berger glomerulonephritis and 10% (N = 4) of Henoch-Schönlein vasculitis patients presented with a pre-existing history of immunoglobulin A-mediated disease. Almost all cases of Berger glomerulonephritis were vaccine-associated (N = 44; 94%), while most cases of Henoch-Schönlein vasculitis were infection-associated (N = 23; 57%). Among vaccine-associated immunoglobulin A diseases, about 90% were associated to mRNA-based vaccines. Our analysis supports the hypothesis that COVID-19 and vaccination against SARS-CoV-2 may trigger or exacerbate an immunoglobulin A-mediated diseases.

Immunoglobulin A Nephropathy in a SARS-CoV-2-Positive Patient With Coexistent Metabolic Syndrome

SARS-CoV-2 viral infection though primarily affects the respiratory system, but concurrent renal involvement is been reported in the medical literature. Acute kidney injury (AKI) is a common finding in SARS-CoV-2-positive patients. An isolated case of IgA nephropathy in a SARS-CoV-2 virus-infected patient has been already reported in the medical literature. Incidence of metabolic syndromes is on the rise considering the change in lifestyle and food habits and the global pandemic of obesity. Renal manifestations of metabolic syndrome are myriad with IgA nephropathy being an occasional manifestation in such patients. We reported a case of IgA nephropathy in a patient in her fourth decade of life diagnosed as metabolic syndrome with concomitant SARS-CoV-2 infection that progressed to chronic kidney damage (CKD) subsequently. In this case report, we postulate that cytokine storm along with hypoxemia secondary to SARS-CoV-2 infection may accelerate the declining renal function however further studies are necessary to confirm this hypothesis considering the rarity of such cases.

Vasculitis flare after COVID-19: report of two cases in patients with preexistent controlled IgA vasculitis and review of the literature

COVID-19 has been related to several autoimmune diseases, triggering the appearance of autoantibodies and endothelial dysfunction. Current evidence has drawn attention to vasculitis-like phenomena and leukocytoclastic vasculitis in some COVID-19 patients. Moreover, it has been hypothesized that COVID-19 could induce flares of preexisting autoimmune disorders. Here, we present two patients with previously controlled IgA vasculitis who developed a renal and cutaneous flare of vasculitis after mild COVID-19, one of them with new-onset ANCA vasculitis. These patients were treated with glucocorticoids and immunosuppressants achieving successful response. We also provide a focused literature review and conclude that COVID-19 may be associated with triggering of vasculitis and could induce flares of previous autoimmune diseases.

IgA vasculitis with nephritis (Henoch-Schönlein purpura) after COVID-19: A case series and review of the literature

COVID-19 most related glomerular disease to date seems to be collapsing glomerulopathy, mostly in young Afroamerican patients with APOL1 gene risk alleles. However, in our population, predominant in elderly Caucasian patients, most biopsied pathology since the beginning of the pandemic has been IgA nephritis or Schönlein-Henoch purpura. Since the description of the first case of this entity after SARS-CoV-2 infection by our research group, three more cases have arisen, which are described in the following article. In contrast to the rest of IgA vasculitis cases reported, our patients presented more renal function deterioration and all of them required immunosupresive therapy. Moreover, some showed incomplete recovery of renal function. This case series strengthens the hypothesis that SARS-CoV-2 infection may be another trigger of this pathology.

Renal autoimmunity: The role of bacterial and viral infections, an extensive review

Autoimmunity is a process by which the loss of self-tolerance results in an immune attack against the body own tissues and organs. For autoimmunity to occur, various elements serving as triggers were described by which infections are considered one of the leading factors. In turn, renal involvement in autoimmune diseases, whether by an organ-specific attack, or as part of a systemic disease process, is well known. As bacterial and viral infections are considered to be common triggers for autoimmunity in general, we aimed to study their association with renal autoimmunity in particular. We performed an extensive search of the recent and relevant medical literature regarding renal autoimmunity syndromes such as infection-associated glomerulonephritis and vasculitis, associated with bacterial and viral infections. By utilizing PubMed and Google Scholar search engines, over 200 articles and case reports were reviewed. Among other mechanisms, direct infection of the renal parenchyma, molecular mimicry, induction of B-cells or secretion of superantigens, bacterial and viral pathogens were found to correlate with the development of renal autoimmunity. Nevertheless, this was not true for all pathogens, as some mimic autoimmune diseases and others show a surprisingly protective effect. The exact immunopathogenesis is yet to be determined, however. For conclusion, bacterial and viral infections are linked to renal autoimmunity by both direct damage and as mediators of systemic diseases. Further research particularly on the immunopathogenetic mechanisms of renal autoimmunity associated with infections is required.

A case of crescentic glomerulonephritis in a patient with COVID-19 infection: A case report and literature review

RATIONALE

Kidney involvement with COVID-19 infection is a well-known complication, and the majority of kidney involvement is related to ischemic injury/acute tubular injury. However, there are some cases of glomerulonephritis, the etiology of which is not yet known, but an immune process is likely to be the trigger.

PATIENT CONCERNS

A 27-year-old man presented to our hospital with facial puffiness and lower-limb swelling.

DIAGNOSIS

Laboratory assessment revealed features of impaired kidney function with proteinuria and hematuria; COVID-19 polymerase chain reaction was positive, which was consistent with pauci-immune crescentic focal segmental glomerulonephritis.

INTERVENTION

After renal biopsy, the patient was started on methylprednisolone and rituximab. Due to worsening kidney parameters, he underwent intermittent hemodialysis as needed.

OUTCOME

Kidney function tests partially improved; he was discharged on oral steroids with follow-up in the nephrology clinic to observe for the need for further hemodialysis.

LESSONS

We conducted a literature review of cases of glomerulonephritis associated with COVID-19 and described numerous types of glomerulonephritis. This report highlights the importance of recognizing emerging glomerulonephritis with COVID-19, the different pathological patterns of renal biopsies, and management interventions and responses.

Spectrum of Kidney Injury Following COVID-19 Disease: Renal Biopsy Findings in a Single Italian Pathology Service

The onset of coronavirus disease (COVID-19) as a pandemic infection, has led to increasing insights on its pathophysiology and clinical features being revealed, such as a noticeable kidney involvement. In this study, we describe the histopathological, immunofluorescence, and ultrastructural features of biopsy-proven kidney injury observed in a series of SARS-CoV-2 positive cases in our institution from April 2020 to November 2021. We retrieved and retrospectively reviewed nine cases (two pediatric and seven adults) that experienced nephrotic syndrome (six cases), acute kidney injury (two cases), and a clinically silent microhematuria and leukocyturia. Kidney biopsies were investigated by means of light microscopy, direct immunofluorescence, and electron microscopy. The primary diagnoses were minimal change disease (four cases), acute tubular necrosis (two cases), collapsing glomerulopathy (two cases), and C3 glomerulopathy (one case). None of the cases showed viral or viral-like particles on ultrastructural analysis. Novel and specific histologic features on kidney biopsy related to SARS-CoV-2 infection have been gradually disclosed and reported, harboring relevant clinical and therapeutic implications. Recognizing and properly diagnosing renal involvement in patients experiencing COVID-19 could be challenging (due to the lack of direct proof of viral infection, e.g., viral particles) and requires a proper integration of clinical and pathological data.

The pathogenesis of COVID-19-induced IgA nephropathy and IgA vasculitis: A systematic review

OBJECTIVE

IgA nephropathy (IgAN) and IgA vasculitis (IgAV) are part of a similar clinical spectrum. Both clinical conditions occur with the coronavirus disease 2019 (COVID-19). This review aims to recognize the novel association of IgAN and IgAV with COVID-19 and describe its underlying pathogenesis.

METHODS

We conducted a systematic literature search and data extraction from PubMed, Cochrane, ScienceDirect, and Google Scholar following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Our search identified 13 cases reporting IgAV and IgAN associated with COVID-19 infection and 4 cases of IgAN following COVID-19 vaccination. The mean, mode, and median ages of patients were 23.8, 4, and 8 years, respectively. Most cases associated with COVID-19 infection were reported in males (77%). Rash and purpura (85%) were the most common clinical features, followed by gastrointestinal symptoms (62%). In symptomatic cases, skin or renal biopsy and immunofluorescence confirmed the diagnosis of IgAN or IgAV. Most patients were treated with steroids and reported recovery or improvement; however, death was reported in two patients.

CONCLUSION

There is a paucity of scientific evidence on the pathogenesis of the association of IgAN and IgAV with COVID-19, which thus needs further study. Current research suggests the role of IgA-mediated immune response, evidenced by early seroconversion to IgA in COVID-19 patients and the role of IgA in immune hyperactivation as the predominant mediator of the disease process. Clinicians, especially nephrologists and paediatricians, need to recognize this association, as this disease is usually self-limited and can lead to complete recovery if prompt diagnosis and treatment are provided.

Kidneys in SARS-CoV-2 Era; a challenge of multiple faces

INTRODUCTION

With the evolution of SARS-CoV-2 pandemic, it was believed to be a direct respiratory virus. But, its deleterious effects were observed on different body systems, including kidneys.

AIM OF WORK

In this review, we tried as much as we can to summarize what has been discussed in the literature about the relation between SARS-CoV-2 infection and kidneys since December, 2019.

METHODS

Each part of the review was assigned to one or two authors to search for relevant articles in three databases (Pubmed, Scopus and Google scholar) and collected data were summarized and revised by two independent researchers.

CONCLUSION

The complexity of COVID-19 pandemic and kidney could be attributed to the direct effect of SARS-CoV-2 infection on the kidneys, different clinical presentation, difficulties confronting dialysis patients, restrictions of the organ transplant programs, poor outcomes and bad prognosis in patients with known history of kidney diseases who got infected with SARS-CoV-2. This article is protected by copyright. All rights reserved.

Canagliflozin Markedly Decreased Proteinuria in a Patient With IgA Nephropathy

IgA nephropathy (IgAN) remains one of the most common forms of glomerulonephritis, especially in developed countries with a low prevalence of infectious diseases. Despite supportive measures that slow the rate of progression of chronic kidney disease (CKD) in IgAN, many patients still progress to end-stage kidney disease. Proteinuria has been shown to be an adverse prognostic factor in IgAN. Data support the use of proteinuria reduction as a reasonably likely surrogate endpoint for a treatment’s effect on progression to end-stage renal disease (ESRD) in IgAN. Currently employed immunosuppressive strategies lack conclusive efficacy data, while there is evidence for treatment-induced toxicity. The current standard of care for the management of IgAN is intensive goal-directed supportive care. Recently the role of sodium-glucose cotransporter 2 (SGLT2) inhibitors in decreasing proteinuria and progression of CKD is widely being recognized. In this case report, we present a 44-year-old male with proteinuria and biopsy-proven IgAN who remained in remission after six months of steroids using the Pozzi protocol. He developed proteinuria five years after remission. At this point, canagliflozin was added to his angiotensin-receptor blocker (ARB) therapy resulting in a significant reduction in his proteinuria. Our case report may intrigue researchers to look into the role of canagliflozin in decreasing albuminuria in non-diabetic kidney disease, thus slowing the progression to ESRD.

Native and transplant kidney histopathological manifestations in association with COVID-19 infection: A systematic review

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can result in clinically significant multi-system disease including involvement in the kidney. The underlying histopathological processes were unknown at the start of the pandemic. As case reports and series have been published describing the underlying renal histopathology from kidney biopsies, we have started to gain an insight into the renal manifestations of this novel disease.

AIM

To provide an overview of the current literature on the renal histopathological features and mechanistic insights described in association with coronavirus disease 2019 (COVID-19) infection.

METHODS

A systematic review was performed by conducting a literature search in the following websites-‘PubMed’, ‘Web of Science’, ‘Embase’ and ‘Medline-ProQuest’ with the following search terms-“COVID-19 AND kidney biopsy”, “COVID-19 AND renal biopsy”, “SARS-CoV-2 AND kidney biopsy” and “SARS-CoV-2 AND renal biopsy”. We have included published data up until February 15, 2021, which includes kidney biopsies (native, transplant and postmortem) from patients with COVID-19. Data on clinical presentation, histopathological features, management and outcome was extracted from the reported studies.

RESULTS

The total number of biopsies reported on here is 288, of which 189 are postmortem, 84 native and 15 transplants. The results are varied and show underlying pathologies ranging from collapsing glomerulopathy and acute tubular injury (ATI) to anti-nuclear cytoplasmic antibody associated vasculitis and pigment nephropathy. There was variation in the specific treatment used for the various renal conditions, which included steroids, hydroxychloroquine, eculizumab, convalescent plasma, rituximab, anakinra, cyclophosphamide and renal replacement therapy, amongst others. The pathological process which occurs in the kidney following COVID-19 infection and leads to the described biopsy findings has been hypothesized in some conditions but not others (for example, sepsis related hypoperfusion for ATI). It is important to note that this represents a very small minority of the total number of cases of COVID-19 related kidney disease, and as such there may be inherent selection bias in the results described. Further work will be required to determine the pathogenetic link, if any, between COVID-19 and the other renal pathologies.

CONCLUSION

This report has clinical relevance as certain renal pathologies have specific management, with the implication that kidney biopsy in the setting of renal disease and COVID-19 should be an early consideration, dependent upon the clinical presentation.

Evidence For and Against Direct Kidney Infection by SARS-CoV-2 in Patients with COVID-19

Despite evidence of multiorgan tropism of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in patients with coronavirus disease 2019 (COVID-19), direct viral kidney invasion has been difficult to demonstrate. The question of whether SARS-CoV2 can directly infect the kidney is relevant to the understanding of pathogenesis of AKI and collapsing glomerulopathy in patients with COVID-19. Methodologies to document SARS-CoV-2 infection that have been used include immunohistochemistry, immunofluorescence, RT-PCR, in situ hybridization, and electron microscopy. In our review of studies to date, we found that SARS-CoV-2 in the kidneys of patients with COVID-19 was detected in 18 of 94 (19%) by immunohistochemistry, 71 of 144 (49%) by RT-PCR, and 11 of 84 (13%) by in situ hybridization. In a smaller number of patients with COVID-19 examined by immunofluorescence, SARS-CoV-2 was detected in 10 of 13 (77%). In total, in kidneys from 102 of 235 patients (43%), the presence of SARS-CoV-2 was suggested by at least one of the methods used. Despite these positive findings, caution is needed because many other studies have been negative for SARS-CoV-2 and it should be noted that when detected, it was only in kidneys obtained at autopsy. There is a clear need for studies from kidney biopsies, including those performed at early stages of the COVID-19-associated kidney disease. Development of tests to detect kidney viral infection in urine samples would be more practical as a noninvasive way to evaluate SARS-CoV-2 infection during the evolution of COVID-19-associated kidney disease.

Henoch-Schönlein Purpura Following the First Dose of COVID-19 Viral Vector Vaccine: A Case Report

A 76 year-old female came to our observation one week after the vaccination with ChAdOx1 nCoV-19 AZD1222 for the onset of purpuric rash on her gluteal and legs regions associated with coxalgia and episodes of macrohaematuria. Henoch-Schönlein purpura (HSP) was diagnosed on the basis of the revised criteria developed by the European League Against Rheumatism, the Paediatric Rheumatology International Trials Organization, and the Paediatric Rheumatology European Society (EULAR/PRINTO/PRES). HSP is a common IgA-mediated small vessel vasculitis, typical of childhood, that affects several systems and is characterized by a tetrad of dermatological, abdominal, joint, and renal manifestations. The Etiology of HSP is not completely understood, but it was observed following upper respiratory tract infections, medications, vaccinations, and malignancies. HSP has previously been reported following immunization with various vaccines, mostly within 12 weeks post, suggesting a possible correlation. To our knowledge, this is the first report of the possible association between COVID-19 ChAdOx1 nCoV-19 AZD1222 and the onset of HSP in a previously healthy woman. No similar cases were reported amongst 23.848 participants in the ChAdOx1 nCoV-19 AZD1222 trial.

COVID-19 and APOL-1 High-Risk Genotype-Associated Collapsing Glomerulonephritis

Coronavirus Disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) primarily affects the lungs and can lead to acute respiratory distress syndrome (ARDS). The ongoing global pandemic has created healthcare and economic crisis for almost every nation of the world. Though primarily affecting the lungs, it has also affected the kidney in various ways including acute kidney injury (AKI), proteinuria, and hematuria. It has been increasingly shown that African American (AA) individuals affected with COVID-19 and presenting with AKI and nephrotic-range proteinuria are very susceptible to focal segmental glomerulosclerosis (FSGS). The APOL-1 gene, associated with the African American population, has been increasingly recognized as a risk factor for FSGS affected with COVID-19. Our case highlights a similar case of COVID-19 in a 65-year-old AA descendant with biopsy-proven FSGS and genetically confirmed APOL-1 alleles.

[Ig a vasculitis with nephritis (henoch-schönlein purpura) after covid-19: a case series and review of the literature.]

La patología glomerular más relacionada con enfermedad COVID-19 hasta la fecha parece ser la glomerulopatía colapsante, principalmente en pacientes de raza afroamericana y con alelos de riesgo para el gen APOL1. No obstante, en nuestra población, conformada por pacientes adultos mayores de raza caucásica, la patología más biopsiada desde el inicio de la pandemia ha sido la nefritis IgA o púrpura de Schönlein-Henoch.

Desde la descripción del primer caso de esta entidad tras infección por SARS-CoV-2 por nuestro grupo de investigación hemos objetivado otros tres, los cuales se describen a continuación. En contraste con el resto de los casos publicados de vasculitis IgA, nuestros pacientes presentaban mayor deterioro de función renal y todos requirieron tratamiento inmunosupresor. Además, algunos presentaron recuperación incompleta de función renal. Esta serie de casos afianza la posibilidad de que la infección por SARS-CoV-2 sea un desencadenante más de esta patología.

A multi-center retrospective cohort study defines the spectrum of kidney pathology in Coronavirus 2019 Disease (COVID-19)

Kidney failure is common in patients with Coronavirus Disease-19 (COVID-19) resulting in increased morbidity and mortality. In an international collaboration, 284 kidney biopsies were evaluated to improve understanding of kidney disease in COVID-19. Diagnoses were compared to five years of 63,575 native biopsies prior to the pandemic and 13,955 allograft biopsies to identify diseases increased in patients with COVID-19. Genotyping for APOL1 G1 and G2 alleles was performed in 107 African American and Hispanic patients. Immunohistochemistry for SARS-CoV-2 was utilized to assess direct viral infection in 273 cases along with clinical information at the time of biopsy. The leading indication for native biopsy was acute kidney injury (45.4%), followed by proteinuria with or without concurrent acute kidney injury (42.6%). There were more African American patients (44.6%) than patients of other ethnicities. The most common diagnosis in native biopsies was collapsing glomerulopathy (25.8%) which associated with high-risk APOL1 genotypes in 91.7% of cases. Compared to the five-year biopsy database, the frequency of myoglobin cast nephropathy and proliferative glomerulonephritis with monoclonal IgG deposits was also increased in patients with COVID-19 (3.3% and 1.7%, respectively), while there was a reduced frequency of chronic conditions (including diabetes mellitus, IgA nephropathy, and arterionephrosclerosis) as the primary diagnosis. In transplants, the leading indication was acute kidney injury (86.4%), for which rejection was the predominant diagnosis (61.4%). Direct SARS-CoV-2 viral infection was not identified. Thus, our multi-center large case series identified kidney diseases that disproportionately affect patients with COVID-19, demonstrated a high frequency of APOL1 high-risk genotypes within this group, with no evidence of direct viral infection within the kidney.

Current Understanding of Clinical Manifestations of COVID-19 in Glomerular Disease

Background

The novel coronavirus disease (COVID-19), also known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is an evolving pandemic with significant mortality. Information about the impact of infection on glomerular disease patients in particular has been lacking. Understanding the virus's effect in glomerular disease is constantly changing. This review article summarizes the data published thus far on COVID-19 and its manifestations in pre-existing and de novo glomerular disease.

Summary

While patients with glomerular disease may be at higher risk of severe COVID-19 due to their immunosuppressed status, some data suggest that a low amount of immunosuppression may be helpful in mitigating the systemic inflammatory response which is associated with high mortality rates in COVID-19. There have been a few case reports on COVID-19 causing glomerular disease relapse in patients. Multiple mechanisms have been proposed for kidney injury, proteinuria, and hematuria in the setting of COVID-19. More commonly, these are caused by direct tubular injury due to hemodynamic instability and hypoxic injury. However, the cytokine storm induced by COVID-19 may trigger common post-viral glomerular disease such as IgA nephropathy, anti-GBM, and ANCA vasculitis that have also been described in COVID-19 patients. Collapsing glomerulopathy, a hallmark of HIV-associated nephropathy, is being reported SARS-CoV-2 cases, particularly in patients with high-risk APOL1 alleles. Direct viral invasion of glomerular structures is hypothesized to cause a podocytopathy due to virus's affinity to ACE2, but evidence for this remains under study.

Key Messages

Infection with SARS-CoV-2 may cause glomerular disease in certain patients. The mechanism of de novo glomerular disease in the setting of COVID-19 is under study. The management of patients with existing glomerular disease poses unique challenges, especially with regard to immunosuppression management. Further studies are needed to inform clinician decisions about the management of these patients during the COVID-19 pandemic.

Pathophysiology of infection with SARS-CoV-2-What is known and what remains a mystery

Coronavirus disease 2019 (COVID‐19), caused by coronavirus severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), has caused extensive disruption and mortality since its recent emergence. Concomitantly, there has been a race to understand the virus and its pathophysiology. The clinical manifestations of COVID‐19 are manifold and not restricted to the respiratory tract. Extrapulmonary manifestations involving the gastrointestinal tract, hepatobiliary system, cardiovascular and renal systems have been widely reported. However, the pathophysiology of many of these manifestations is controversial with questionable support for direct viral invasion and an abundance of alternative explanations such as pre‐existing medical conditions and critical illness. Prior research on SARS‐Co‐V and NL63 was rapidly leveraged to identify angiotensin‐converting enzyme 2 (ACE2) receptor as the key cell surface receptor for SARS‐CoV‐2. The distribution of ACE2 has been used as a starting point for estimating vulnerability of various tissue types to SARS‐CoV‐2 infection. Sophisticated organoid and animal models have been used to demonstrate such infectivity of extrapulmonary tissues in vitro, but the clinical relevance of these findings remains uncertain. Clinical autopsy studies are typically small and inevitably biased towards patients with severe COVID‐19 and prolonged hospitalization. Technical issues such as delay between time of death and autopsy, use of inappropriate antibodies for paraffin‐embedded tissue sections and misinterpretation of cellular structures as virus particles on electron micrograph images are additional problems encountered in the extant literature. Given that SARS‐CoV‐2 is likely to circulate permanently in human populations, there is no doubt that further work is required to clarify the pathobiology of COVID‐19.