BackgroundReports show that AKI is a common complication of severe coronavirus disease 2019 (COVID-19) in hospitalized patients. Studies have also observed proteinuria and microscopic hematuria in such patients. Although a recent autopsy series of patients who died with severe COVID-19 in China found acute tubular necrosis in the kidney, a few patient reports have also described collapsing glomerulopathy in COVID-19.MethodsWe evaluated biopsied kidney samples from ten patients at our institution who had COVID-19 and clinical features of AKI, including proteinuria with or without hematuria. We documented clinical features, pathologic findings, and outcomes.ResultsOur analysis included ten patients who underwent kidney biopsy (mean age: 65 years); five patients were black, three were Hispanic, and two were white. All patients had proteinuria. Eight patients had severe AKI, necessitating RRT. All biopsy samples showed varying degrees of acute tubular necrosis, and one patient had associated widespread myoglobin casts. In addition, two patients had findings of thrombotic microangiopathy, one had pauci-immune crescentic GN, and another had global as well as segmental glomerulosclerosis with features of healed collapsing glomerulopathy. Interestingly, although the patients had confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection by RT-PCR, immunohistochemical staining of kidney biopsy samples for SARS-CoV-2 was negative in all ten patients. Also, ultrastructural examination by electron microscopy showed no evidence of viral particles in the biopsy samples.ConclusionsThe most common finding in our kidney biopsy samples from ten hospitalized patients with AKI and COVID-19 was acute tubular necrosis. There was no evidence of SARS-CoV-2 in the biopsied kidney tissue.

Chronic kidney disease (CKD) remains one of the leading causes of death in the developed world and acute kidney injury (AKI) is now recognized as a major risk factor in its development. Understanding the factors leading to CKD after acute injury are limited by current animal models of AKI which concurrently target various kidney cell types such as epithelial, endothelial and inflammatory cells. Here we developed a mouse model of kidney injury using the Six2-Cre-LoxP technology to selectively activate expression of the simian diphtheria toxin receptor in renal epithelia derived from the metanephric mesenchyme. By adjusting the timing and dose of diphtheria toxin a highly selective model of tubular injury was created to define the acute and chronic consequences of isolated epithelial injury. The diphtheria toxin-induced sublethal tubular epithelial injury was confined to the S1 and S2 segments of the proximal tubule rather than being widespread in the metanephric mesenchyme derived epithelial lineage. Acute injury was promptly followed by inflammatory cell infiltration and robust tubular cell proliferation leading to complete recovery after a single toxin insult. In striking contrast, three insults to renal epithelial cells at one week intervals resulted in maladaptive repair with interstitial capillary loss, fibrosis and glomerulosclerosis which was highly correlated with the degree of interstitial fibrosis. Thus, selective epithelial injury can drive the formation of interstitial fibrosis, capillary rarefaction and potentially glomerulosclerosis, substantiating a direct role for damaged tubule epithelium in the pathogenesis of CKD.

Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre-including this research content-immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active. cyclosporine. The patient was hydrated, and antibiotic prophylaxis was started (Table 1). Unfortunately, the patient's respiratory function further deteriorated, and laboratory findings were suggestive of cytokine release syndrome with remarkably elevated (431 pg/ml) serum interleukin-6 levels. A single i.v. infusion of tocilizumab (8 mg/kg per d) was attempted. Two days after, oxygen was no longer required (Figure 1). The patient was discharged home and completely recovered from acute kidney injury. Early detection of cytokine release syndrome biomarkers is recommended and should prompt anti-inflammatory interventions. Larger studies are needed to confirm the utility and safety of interleukin-6 inhibition combined with dexamethasone in kidney transplant recipients with COVID-19. 1. Qin C, Zhou L, Hu Z, et al. Dysregulation of immune response in patients with COVID-19 in Wuhan, China [e-pub ahead of print]. Clin Infect Dis.

No abstract

No abstract

MicroRNAs (miRNAs) are endogenous noncoding RNA molecules that are involved in post-transcriptional gene silencing. Using global miRNA expression profiling, we found miR-21, -155, and 18a to be highly upregulated in rat kidneys following tubular injury induced by ischemia/reperfusion (I/R) or gentamicin administration. Mir-21 and -155 also showed decreased expression patterns in blood and urinary supernatants in both models of kidney injury. Furthermore, urinary levels of miR-21 increased 1.2-fold in patients with clinical diagnosis of acute kidney injury (AKI) (n = 22) as compared with healthy volunteers (n = 25) (p < 0.05), and miR-155 decreased 1.5-fold in patients with AKI (p < 0.01). We identified 29 messenger RNA core targets of these 3 miRNAs using the context likelihood of relatedness algorithm and found these predicted gene targets to be highly enriched for genes associated with apoptosis or cell proliferation. Taken together, these results suggest that miRNA-21 and -155 could potentially serve as translational biomarkers for detection of AKI and may play a critical role in the pathogenesis of kidney injury and tissue repair process.

Acute kidney injury (AKI) is common among hospitalized patients with Coronavirus Infectious Disease 2019 (COVID-19), with the occurrence of AKI ranging from 0.5% to 80%. The variability in the occurrence of AKI has been attributed to the difference in geographic locations, race/ethnicity, and severity of illness. AKI among hospitalized patients is associated with increased length of stay and in-hospital deaths. Even patients with AKI who survive to hospital discharge are at risk of developing chronic kidney disease (CKD) or end-stage kidney disease (ESKD). An improved knowledge of the pathophysiology of AKI in COVID-19 is crucial to mitigate and manage AKI and to improve the survival of patients who developed AKI during COVID-19. The goal of this article is to provide our current understanding of the etiology and the pathophysiology of AKI in the setting of COVID-19.

Pathologic changes in nonneoplastic renal parenchyma of nephrectomy specimens for renal tumors and the significance of these changes with regard to the outcome of contralateral kidney function have not been studied previously. We examined the nonneoplastic renal parenchymal changes in 110 consecutive tumor nephrectomy specimens, and we correlated our findings with patients' clinical information. The material was examined for the presence of any glomerular, tubulointerstitial, or vascular pathology. In our analysis, only about 10% of cases had unremarkable renal parenchyma and vasculature. A further 28% of cases had unremarkable parenchyma, but some degree of vascular sclerosis was noted. The remaining cases (>60%) had evident pathologic abnormalities, most commonly related to vascular disease or diabetes mellitus. Regardless of the type of renal cancer they have, the majority of our cases can be placed in one of three principal groups: 1) unremarkable kidney parenchyma, with or without vascular sclerosis (38%); 2) parenchymal scarring and marked vascular changes, including cases of atheroembolic disease, and chronic thrombotic microangiopathy (28%); and 3) changes related to diabetes mellitus, such as glomerular hypertrophy, mesangial expansion, and diffuse glomerulosclerosis (24%). Follow-up data on serum creatinine 6 months postoperatively were available in a third of our patients. Patients with severe histopathologic findings (parenchymal scarring with >20% global glomerulosclerosis and advanced diffuse diabetic glomerulosclerosis) showed a significant change in serum creatinine from the preoperative period to 6 months after radical nephrectomy (P=0.001), indicative of progressive worsening of renal function; this change is significantly greater than that seen in patients with unremarkable renal parenchyma (P=0.01). We conclude that adequate examination of nonneoplastic renal parenchyma is an important tool in recognizing patients at risk for progressive renal disease after nephrectomy and could be an essential step in providing early preventive and treatment measures and better medical care of patients undergoing nephrectomy for neoplastic processes.