Multidisciplinary basic and clinical research of acute kidney injury with COVID-19: Pathophysiology, mechanisms, incidence, management and kidney transplantation

Crescentic Glomerulonephritis Possibly Caused by COVID-19 Infection

Background: The COVID-19 (coronavirus disease 2019) pandemic has presented a serious challenge to nephrologists, since it can lead to severe kidney injury in the form of acute tubular necrosis, with many patients requiring renal replacement therapy. This is predominantly seen in people who develop severe respiratory manifestations like ARDS (acute respiratory distress syndrome) from the viral infection, a cytokine storm or septic shock with unstable hemodynamics. It also presents with various glomerular injuries, mainly collapsing glomerulopathy in high-risk APOL1 (Apolipoprotein L1) genotype patients, thrombotic microangiopathy-related renal failure due to hyper coagulopathy and occasionally pauci-immune glomerulonephritis due to immune dysregulation. All the glomerular disorders that are caused by COVID-19 infection have been described under the designation COVAN (COVID-19-associated nephropathy). Proteinuria is a predominant presentation in glomerular disorders. Gross hematuria and AKI without any respiratory symptoms from COVID-19 infection have not been described so far in the literature. We are presenting one such rare case here. Methods: We have encountered a rare case of gross hematuria and severe acute renal failure. His serological work up was negative for all autoimmune etiologies that can cause Glomerulonephritis. He was found to have infection-related crescentic glomerulonephritis due to active COVID-19 infections discovered via kidney biopsy. He tested positive for SARS-CoV-2 but didn't have any clinical respiratory symptoms. He has responded well to treatment with a steroid taper and antiviral medication (Remdesivir). This is a very rare renal manifestation of COVID-19 infection. Results: COVID-19 infection can result in crescentic glomerulonephritis. This can be diagnosed by kidney biopsy which shows extensive c3 deposits, tubuloreticular inclusion bodies along with crescentic lesions. This responds to treatment with steroids and Antiviral agents. Conclusions: Crescentic Glomerulonephritis should be considered as a possible etiology for severe acute kidney injury with hematuria in patients with active covid-19 infection without any respiratory symptoms. Kidney biopsy helps in diagnosing it and responds to treatment with steroids and antivirals.

New insights into kidney disease after COVID-19 infection and vaccination: histopathological and clinical findings

In addition to its pulmonary effects, coronavirus disease 2019 (COVID-19) has also been found to cause acute kidney injury (AKI), which has been linked to high mortality rates. In this review, we collected data from 20 clinical studies on post-COVID-19-related AKI and 97 cases of AKI associated with COVID-19 vaccination. Acute tubular injury was by far the most common finding in the kidneys of patients with COVID-19-related AKI. Among patients hospitalized for COVID-19, 34.0% developed AKI, of which 59.0%, 19.1% and 21.9% were Stages 1, 2 and 3, respectively. Though kidney disease and other adverse effects after COVID-19 vaccination overall appear rare, case reports have accumulated suggesting that COVID-19 vaccination may be associated with a risk of subsequent kidney disease. Among the patients with post-vaccination AKI, the most common pathologic findings include crescentic glomerulonephritis (29.9%), acute tubular injury (23.7%), IgA nephropathy (18.6%), antineutrophil cytoplasmic autoantibody-associated vasculitis (17.5%), minimal change disease (17.5%) and thrombotic microangiopathy (10.3%). It is important to note that crescentic glomerulonephritis appears to be more prevalent in patients who have newly diagnosed renal involvement. The proportions of patients with AKI Stages 1, 2 and 3 after COVID-19 vaccination in case reports were 30.9%, 22.7% and 46.4%, respectively. In general, clinical cases of new-onset and recurrent nephropathy with AKI after COVID-19 vaccination have a positive prognosis. In this article, we also explore the underlying pathophysiological mechanisms of AKI associated with COVID-19 infection and its vaccination by describing key renal morphological and clinical features and prognostic findings.

The nuclear factor kappa B signaling pathway is a master regulator of renal fibrosis

Renal fibrosis is increasingly recognized as a global public health problem. Acute kidney injury (AKI) and chronic kidney disease (CKD) both result in renal fibrosis. Oxidative stress and inflammation play central roles in progressive renal fibrosis. Oxidative stress and inflammation are closely linked and form a vicious cycle in which oxidative stress induces inflammation through various molecular mechanisms. Ample evidence has indicated that a hyperactive nuclear factor kappa B (NF-ƙB) signaling pathway plays a pivotal role in renal fibrosis. Hyperactive NF-ƙB causes the activation and recruitment of immune cells. Inflammation, in turn, triggers oxidative stress through the production of reactive oxygen species and nitrogen species by activating leukocytes and resident cells. These events mediate organ injury through apoptosis, necrosis, and fibrosis. Therefore, developing a strategy to target the NF-ƙB signaling pathway is important for the effective treatment of renal fibrosis. This Review summarizes the effect of the NF-ƙB signaling pathway on renal fibrosis in the context of AKI and CKD (immunoglobulin A nephropathy, membranous nephropathy, diabetic nephropathy, hypertensive nephropathy, and kidney transplantation). Therapies targeting the NF-ƙB signaling pathway, including natural products, are also discussed. In addition, NF-ƙB-dependent non-coding RNAs are involved in renal inflammation and fibrosis and are crucial targets in the development of effective treatments for kidney disease. This Review provides a clear pathophysiological rationale and specific concept-driven therapeutic strategy for the treatment of renal fibrosis by targeting the NF-ƙB signaling pathway.

Prognostic significance of early acute kidney injury in COVID-19 patients requiring mechanical ventilation: a single-center retrospective analysis

Acute kidney injury (AKI) is associated with impaired outcomes in critically ill COVID-19 patients. However, the prognostic significance of early AKI is poorly described. We aimed to determine whether AKI on admission to the intensive care unit (ICU) and its development within the first 48 h predict the need for renal replacement therapy (RRT) and increased mortality. An analysis of 372 patients with COVID-19 pneumonia requiring mechanical ventilation without advanced chronic kidney disease from 2020 to 2021 was performed. The AKI stages on ICU admission and Day 2 were determined using adapted KDIGO criteria. The early development of renal function was assessed by the change in AKI score and the Day-2/Day-0 creatinine ratio. Data were compared between three consecutive COVID-19 waves and with data before the pandemic. Both ICU and 90-day mortality (79% and 93% vs. 35% and 44%) and the need for RRT increased markedly with advanced AKI stage on ICU admission. Similarly, an early increase in AKI stage and creatinine implied highly increased mortality. RRT was associated with very high ICU and 90-day mortality (72% and 85%), even surpassing that of patients on ECMO. No difference was found between consecutive COVID-19 waves, except for a lower mortality in the patients on RRT in the last omicron wave. Mortality and need for RRT were comparable in the COVID-19 and pre-COVID-19 patients, except that RRT did not increase ICU mortality in the pre-COVID-19 era. In conclusion, we confirmed the prognostic significance of both AKI on ICU admission and its early development in patients with severe COVID-19 pneumonia.

Transforming growth factor-β signaling: From tissue fibrosis to therapeutic opportunities

Fibrosis refers to the excessive deposition of extracellular matrix components in the processes of wound repair or tissue regeneration after tissue damage. Fibrosis occurs in various organs such as lung, heart, liver, and kidney tissues, resulting in the failure of organ structural integrity and its functional impairment. It has long been thought to be relentlessly progressive and irreversible process, but both preclinical models and clinical trials in multiorgans have shown that fibrosis is a highly dynamic process. Transforming growth factor-beta (TGF-β) is a superfamily of related growth factors. Many studies have described that activation of profibrotic TGF-β signaling promotes infiltration and/or proliferation of preexisting fibroblasts, generation of myofibroblasts, extracellular matrix deposition, and inhibition of collagenolysis, which leads to fibrosis in the pathological milieu. This review describes the effect of TGF-β signaling in fibrotic-associate lung, heart, liver, and kidney tissues, followed by a detailed discussion of canonical and non-canonical TGF-β signaling pathway. In addition, this review also discusses therapeutic options by using natural products and chemical agents, for targeting tissue fibrosis via modulating TGF-β signaling to provide a more specific concept-driven therapy strategy for multiorgan fibrosis.

Acute Kidney Injury in COVID-19 Patients: Pathogenesis, Clinical Characteristics, Therapy, and Mortality

Coronavirus disease 2019 (COVID-19) is a disease caused by infection with the SARS-CoV-2 virus and has represented one of the greatest challenges humanity has faced in recent years. The virus can infect a large number of organs, including the lungs and upper respiratory tract, brain, liver, kidneys, and intestines, among many others. Although the greatest damage occurs in the lungs, the kidneys are not exempt, and acute kidney injury (AKI) can occur in patients with COVID-19. Indeed, AKI is one of the most frequent and serious organic complications of COVID-19. The incidence of COVID-19 AKI varies widely, and the exact mechanisms of how the virus damages the kidney are still unknown. For this reason, the purpose of this review was to assess current findings on the pathogenesis, clinical features, therapy, and mortality of COVID-19 AKI.