Pathophysiology and Clinical Manifestations of COVID-19-Related Acute Kidney Injury-The Current State of Knowledge and Future Perspectives

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.

Atypical Hemolytic Uremic Syndrome Associated with BNT162b2 mRNA COVID-19 Vaccine in a Kidney Transplant Recipient: A Case Report and Literature Review

Case Report: We report a case of a 37-year-old female with kidney transplant, who was admitted at our hospital due to worsening renal function, nephrotic proteinuria, and anemia developed 21 days after the second dose of BNT162b2 COVID-19 vaccine (Pfizer-BioNTech). Laboratory tests revealed hemolytic anemia, thrombocytopenia, and acute kidney injury. Given the clinical picture of Thrombotic Micro-angiopathy (TMA) and severe renal impairment, plasma exchange (PEX) and dialysis were immediately started. Laboratory workup showed low C3 and C4 levels, normal activity of ADAMTS13, and the absence of anti-factor H antibodies. Molecular biology investigations revealed a heterozygous variant in exon 22 (SCR20) of the CFH gene (c.3628C>T; p.Arg1210Cys) described as an atypical Hemolytic Uremic Syndrome (aHUS) causative mutation. Our patient completed two sessions of PEX followed by eculizumab treatment with hematological improvement but no recovery of renal function. This is the first reported case of aHUS triggered by SARS-CoV-2 vaccination in a kidney transplant patient without recovery of renal function. Conclusion: Although rare, clinicians should be aware of possible nephrological complications that may appear after vaccination.

Metabolism configures immune response across multi-systems: Lessons from COVID-19

Several studies over the last decade demonstrate the recruitment of immune cells, increased inflammatory cytokines, and chemokine in patients with metabolic diseases, including heart failure, parenchymal inflammation, obesity, tuberculosis, and diabetes mellitus. Metabolic rewiring of immune cells is associated with the severity and prevalence of these diseases. The risk of developing COVID-19/SARS-CoV-2 infection increases in patients with metabolic dysfunction (heart failure, diabetes mellitus, and obesity). Several etiologies, including fatigue, dyspnea, and dizziness, persist even months after COVID-19 infection, commonly known as Post-Acute Sequelae of CoV-2 (PASC) or long COVID. A chronic inflammatory state and metabolic dysfunction are the factors that contribute to long COVID. Here, this study explores the potential link between pathogenic metabolic and immune alterations across different organ systems that could underlie COVID-19 and PASC. These interactions could be utilized for targeted future therapeutic approaches.

Acute kidney injury in patients with COVID-19 compared to those with influenza: a systematic review and meta-analysis

Background

COVID-19 and influenza can both lead to acute kidney injury (AKI) as a common complication. However, no meta-analysis has been conducted to directly compare the incidence of AKI between hospitalized patients with COVID-19 and influenza. The objective of our study aims to investigate the incidence and outcomes of AKI among hospitalized patients between these two groups.

Materials and methods

A systematic search of PubMed, Embase, and Cochrane databases was conducted from December 2019 to August 2023 to identify studies examining AKI and clinical outcomes among hospitalized patients with COVID-19 and influenza. The primary outcome of interest was the incidence of AKI, while secondary outcomes included in-hospital mortality, recovery from AKI, hospital and ICU stay duration. The quality of evidence was evaluated using Cochrane and GRADE methods.

Results

Twelve retrospective cohort studies, involving 17,618 hospitalized patients with COVID-19 and influenza, were analyzed. COVID-19 patients showed higher AKI incidence (29.37% vs. 20.98%, OR: 1.67, 95% CI 1.56-1.80, p < 0.01, I2 = 92.42%), and in-hospital mortality (30.95% vs. 5.51%, OR: 8.16, 95% CI 6.17-10.80, p < 0.01, I2 = 84.92%) compared to influenza patients with AKI. Recovery from AKI was lower in COVID-19 patients (57.02% vs., 80.23%, OR: 0.33, 95% CI 0.27-0.40, p < 0.01, I2 = 85.17%). COVID-19 patients also had a longer hospital stay (SMD: 0.69, 95% CI 0.65-0.72, p < 0.01, I2 = 98.94%) and longer ICU stay (SMD: 0.61, 95% CI 0.50-0.73, p < 0.01, I2 = 94.80%) than influenza patients. In our study, evidence quality was high (NOS score 7-9), with low certainty for AKI incidence and moderate certainty for recovery form AKI by GRADE assessment.

Conclusion

COVID-19 patients had higher risk of developing AKI, experiencing in-hospital mortality, and enduring prolonged hospital/ICU stays in comparison to influenza patients. Additionally, the likelihood of AKI recovery was lower among COVID-19 patients.

Crosstalk between COVID-19 Infection and Kidney Diseases: A Review on the Metabolomic Approaches

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19, a respiratory disorder. Various organ injuries have been reported in response to this virus, including kidney injury and, in particular, kidney tubular injury. It has been discovered that infection with the virus does not only cause new kidney disease but also increases treatment difficulty and mortality rates in people with kidney diseases. In individuals hospitalized with COVID-19, urinary metabolites from several metabolic pathways are used to distinguish between patients with acute kidney injury (AKI) and those without. This review summarizes the pathogenesis, pathophysiology, treatment strategies, and role of metabolomics in relation to AKI in COVID-19 patients. Metabolomics is likely to play a greater role in predicting outcomes for patients with kidney disease and COVID-19 with varying levels of severity in the near future as data on metabolic profiles expand rapidly. Here, we also discuss the correlation between COVID-19 and kidney diseases and the available metabolomics approaches.

Targeting TLR-4 Signaling to Treat COVID-19-induced Acute Kidney Injury

The newly discovered severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) has turned into a potentially fatal pandemic illness. Numerous acute kidney injury (AKI) cases have been reported, although diffuse alveolar destruction and acute respiratory failure are the major symptoms of SARS-CoV-2 infection. The AKI, often known as a sudden loss of kidney function, carries a greater risk of mortality and morbidity. AKI was the second most frequent cause of death after acute respiratory distress syndrome (ARDS) in critically ill patients with coronavirus disease 2019 (COVID-19). While most patients with COVID-19 have moderate symptoms, some have severe symptoms, such as septic shock and ARDS. Also, it has been proven that some patients have severe symptoms, such as the failure of several organs. The kidneys are often affected either directly or indirectly. The major signs of kidney involvement are proteinuria and AKI. It is hypothesized that multiple mechanisms contribute to kidney injury in COVID-19. Direct infection of podocytes and proximal tubular cells in the kidneys may lead to acute tubular necrosis and collapsing glomerulopathy. SARS-CoV2 may also trigger a cascade of immunological responses that lead to AKI, including cytokine storm (CS), macrophage activation syndrome, and Toll-like receptor type-4 activation (TLR-4). Other proposed processes of AKI include interactions between organs, endothelial failure, hypercoagulability, rhabdomyolysis, and sepsis.

Furthermore, ischemic damage to the kidney might result from the decreased oxygen supply. This article focuses on kidney injury’s epidemiology, etiology, and pathophysiological processes. Specifically, it focuses on the CS and the role of TLR-4 in this process. To effectively manage and treat acute kidney damage and AKI in COVID-19, it is crucial to understand the underlying molecular pathways and pathophysiology.

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.

Exploring Urinary Extracellular Vesicles and Immune Mediators as Biomarkers of Kidney Injury in COVID-19 Hospitalized Patients

Kidney injury is an important outcome associated with COVID-19 severity. In this regard, alterations in urinary extracellular vesicles (uEVs) could be detected in the early phases of renal injury and may be reflective of the inflammatory process. This is an observational study performed with a case series of COVID-19 hospitalized patients presenting mild-to-critical disease. Total and podocyte-derived uEVs were identified by nanoscale flow cytometry, and urinary immune mediators were assessed by a multiplex assay. We studied 36 patients, where 24 (66.7%) were considered as mild/moderate and 12 (33.3%) as severe/critical. Increased levels of total uEVs were observed (p = 0.0001). Importantly, total uEVs were significantly higher in severe/critical patients who underwent hemodialysis (p = 0.03) and were able to predict this clinical outcome (AUC 0.93, p = 0.02). Severe/critical patients also presented elevated urinary levels (p < 0.05) of IL-1β, IL-4, IL-6, IL-7, IL-16, IL-17A, LIF, CCL-2, CCL-3, CCL-11, CXCL-10, FGFb, M-CSF, and CTAcK. Lastly, we observed that total uEVs were associated with urinary immune mediators. In conclusion, our results show that early alterations in urinary EVs could identify patients at higher risk of developing renal dysfunction in COVID-19. This could also be relevant in different scenarios of systemic and/or infectious disease.

Suppressed renoprotective purines in COVID-19 patients with acute kidney injury

Acute kidney injury (AKI) is common in patients hospitalized for COVID-19, complicating their clinical course and contributing to worse outcomes. Animal studies show that adenosine, inosine and guanosine protect the kidney against some types of AKI. However, until now there was no evidence in patients supporting the possibility that abnormally low kidney levels of adenosine, inosine and guanosine contribute to AKI. Here, we addressed the question as to whether these renoprotective purines are altered in the urine of COVID-19 patients with AKI. Purines were measured by employing ultra-high-performance liquid chromatography-tandem mass spectrometry with stable-isotope-labeled internal standards for each purine of interest. Compared with COVID-19 patients without AKI (n = 23), COVID-19 patients with AKI (n = 20) had significantly lower urine levels of adenosine (P < 0.0001), inosine (P = 0.0008), and guanosine (P = 0.0008) (medians reduced by 85%, 48% and 61%, respectively) and lower levels (P = 0.0003; median reduced by 67%) of the 2nd messenger for A2A and A2B adenosine receptors, i.e., 3',5'-cAMP. Moreover, in COVID-19 patients with AKI, urine levels of 8-aminoguanine (endogenous inhibitor of inosine and guanosine metabolism) were nearly abolished (P < 0.0001). In contrast, the "upstream" precursors of renoprotective purines, namely 5'-AMP and 5'-GMP, were not significantly altered in COVID-19 patients with AKI, suggesting defective conversion of these precursors by CD73 (converts 5'-AMP to adenosine and 5'-GMP to guanosine). These findings imply that an imbalance in renoprotective purines may contribute to AKI in COVID-19 patients and that pharmacotherapy targeted to restore levels of renoprotective purines may attenuate the risk of AKI in susceptible patients with COVID-19.

Molecular Mechanisms of Rhabdomyolysis-Induced Kidney Injury: From Bench to Bedside

Rhabdomyolysis-induced acute kidney injury (RIAKI) occurs following damage to the muscular sarcolemma sheath, resulting in the leakage of myoglobin and other metabolites that cause kidney damage. Currently, the sole recommended clinical treatment for RIAKI is aggressive fluid resuscitation, but other potential therapies, including pretreatments for those at risk for developing RIAKI, are under investigation. This review outlines the mechanisms and clinical significance of RIAKI, investigational treatments and their specific targets, and the status of ongoing research trials.

Atypical Hemolytic Uremic Syndrome after SARS-CoV-2 Infection: Report of Two Cases

Atypical hemolytic uremic syndrome (aHUS) is a life-threatening disease causing systemic thrombotic microangiopathy (TMA) due to the fact of complement dysregulation. Immune activation by viruses, including SARS-CoV-2, can lead to the development of an episode of aHUS against a background of genetic dysregulation in the complement pathway. This paper presents an analysis of two cases of aHUS-siblings diagnosed with familial disease, with a genetic predisposition to aHUS, in whom infection with SARS-CoV-2 was a strong trigger of disease recurrence. The quick recognition and treatment with eculizumab in the early stage of the disease resulted in a rapid improvement in clinical conditions and laboratory parameters.

Acute kidney injury associated to COVID-19 leads to a strong unbalance of circulant immune mediators

BACKGROUND

Severe cases of coronavirus disease 2019 (COVID-19) have increased risk for acute kidney injury (AKI). The exacerbation of the immune response seems to contribute to AKI development, but the immunopathological process is not completely understood.

OBJECTIVES

To analyze levels of circulant immune mediators in COVID-19 patients evolving with or without AKI. We have also investigated possible associations of these mediators with viral load and clinical outcomes.

METHODS

This is a longitudinal study performed with hospitalized patients with moderate to severe COVID-19. Serum levels of 27 immune mediators were measured by a multiplex immunoassay. Data were analyzed at two timepoints during the follow-up: within the first 13 days of the disease onset (early sample) and from the 14th day to death or hospital discharge (follow-up sample).

RESULTS

We studied 82 COVID-19 patients (59.5 ± 17.5 years, 54.9% male). Of these, 34 (41.5%) developed AKI. These patients presented higher SARS-CoV-2 viral load (P = 0.03), higher frequency of diabetes (P = 0.01) and death (P = 0.0004). Overall, AKI patients presented significantly higher and sustained levels (P < 0.05) of CCL-2, CCL-3, CCL-4, CXCL-8, CXCL-10, IFN-γ, IL-2, IL-6, TNF-α, IL-1Ra, IL-10 and VEGF. Importantly, higher levels of CCL-2, CXCL-10, IL-2, TNF-α, IL-10, FGFb, and VEGF were observed in AKI patients independently of death. ROC curves demonstrated that early alterations in CCL-2, CXCL-8, CXCL-10, IFN-γ, IL-6, IL-1Ra and IL-10 show a good predictive value regarding AKI development. Lastly, immune mediators were significantly associated with each other and with SARS-CoV-2 viral load in AKI patients.

CONCLUSIONS

COVID-19 associated AKI is accompanied by substantial alterations in circulant levels of immune mediators, which could significantly contribute to the establishment of kidney injury.

How Does SARS-CoV-2 Affect Our Eyes-What Have We Learnt So Far about the Ophthalmic Manifestations of COVID-19?

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection has become a worldwide threat resulting in a pandemic in 2020. SARS-CoV-2 infection manifests itself as coronavirus disease 2019 (COVID-19) that is evidenced in a vast number of either specific or nonspecific symptoms. Except for typical (but nonspecific) symptoms such as fever, dry cough, or muscle weakness, the infected patients might also present atypical symptoms including neurological, dermatological, or ophthalmic manifestations. This paper summarizes the current state of knowledge regarding the onset, progression, and types of ophthalmic symptoms induced by SARS-CoV-2 infection recognized amongst the infected patients.

Circulating Microparticles in the Pathogenesis and Early Anticoagulation of Thrombosis in COVID-19 With Kidney Injury

As more is learned about the pathophysiological mechanisms of COVID-19, systemic thrombosis has been recognized as being associated with more severe clinical manifestations, mortality and sequelae. As many as 40% of patients admitted to the hospital due to COVID-19 have acute kidney injury, with coagulation abnormalities the main cause of impaired function. However, the mechanism of renal thrombosis and the process leading to kidney injury are unclear. Microparticles (MPs) are membrane bubbles released in response to activation, injury or apoptosis of cells. The phosphatidylserine (PS) exposed on the surface of MPs provides binding sites for endogenous and exogenous FXase complexes and prothrombin complexes, thus providing a platform for the coagulation cascade reaction and facilitating clot formation. In the context of COVID-19 infection, viral attack leads immune cells to release cytokines that damage circulating blood cells and vascular endothelial cells, resulting in increased MPs levels. Therefore, MPs can be used as a risk factor to predict renal microthrombosis and kidney injury. In this paper, we have summarized the latest data on the pathophysiological mechanism and treatment of renal thrombosis caused by MPs in COVID-19, revealing that the coagulation abnormality caused by MP and PS storms is a universal progression that aggravates the mortality and sequelae of COVID-19 and potentially other pandemic diseases. This paper also describes the risk factors affecting renal thrombosis in COVID-19 from the perspective of the Virchow’s triad: blood hypercoagulability, vascular endothelial injury, and decreased blood flow velocity. In summary, given the serious consequences of thrombosis, current guidelines and clinical studies suggest that early prophylactic anticoagulant therapy reduces mortality and improves clinical outcomes. Early anticoagulation, through inhibition of PS-mediated coagulopathy, allows maintenance of unobstructed blood circulation and oxygen delivery thereby facilitating the removal of inflammatory factors, viruses, MPs, and dead or damaged cells, and expediting patient rehabilitation.