ACE and ACE2 in kidney disease

The Influence of Anti-PAR 1 and Anti-ACE 2 Antibody Levels on the Course of Specific Glomerulonephritis Types

Background: Anti-PAR 1 (protease-activated receptor 1) and anti-ACE 2 (angiotensin 2-converting enzyme 2) antibodies are a kind of non-HLA (human leukocyte antigens) antibodies postulated to be of significance in autoimmunological diseases and organ transplantation. Methods: We assessed anti-PAR 1 and anti-ACE 2 antibody levels in patients with membranous nephropathy n= 18, focal and segmental glomerulosclerosis (FSGS) n = 25, lupus nephritis (LN) n = 17, IgA nephropathy n = 14, mesangial proliferative (non-IgA) glomerulonephritis n = 6, c-ANCA (cytoplasmic anti-neutrophil cytoplasmic antibodies) vasculitis n = 40, p (perinuclear)-ANCA vasculitis n = 16, and compared them with a healthy control group n = 22. Next, we observed the clinical course of the patients (creatinine, total protein, and albumin) up to 2 years and correlated the results with the level of antibodies. Results: The anti-PAR 1 antibody level was lower in membranous nephropathy and FSGS compared to the control group. Anti-PAR 1 antibody levels were higher in secondary compared to primary glomerulonephritis. Both anti-PAR 1 and anti-ACE 2 antibody levels correlated positively (in focal and segmental glomerulosclerosis) or negatively (in lupus nephritis) with total protein and albumin at different time points of observation. Anti-PAR 1 and anti-ACE 2 antibody levels correlated also with creatinine level at one time point of observation in IgA nephropathy. Anti-PAR 1 and anti-ACE 2 antibodies correlated with each other in membranous nephropathy, FSGS, and p- and c-ANCA vasculitis (p < 0.05). Conclusions: The anti-PAR 1 antibody level was lower in membranous nephropathy and focal and segmental glomerulosclerosis compared to the control group. Anti-PAR 1 antibody levels tend to be higher in secondary compared to primary glomerulonephritis.

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.

Novel Antihypertensive Medications to Target the Renin-Angiotensin System: Mechanisms and Research

An estimated 1.28 billion individuals in the global population suffer from hypertension. Importantly, uncontrolled hypertension is strongly linked to various cardiovascular and cerebrovascular diseases. The role of the renin-angiotensin system (RAS) is widely acknowledged in the development and progression of hypertension. This system comprises angiotensinogen, the renin/(pro)renin/(pro)renin receptor (PRR) axis, the renin/angiotensin-converting enzyme/angiotensin (Ang) II/Ang II type I receptor (AT1R) axis, the renin/angiotensin-converting enzyme (ACE) 2/Ang (1-7)/Mas receptor (MasR) axis, the alamandine/Mas-related G protein-coupled D (MrgD) receptor axis, and the renin/ACE/Ang II/Ang II type II receptor (AT2R) axis. Additionally, brain Ang III plays a vital role in regulating central blood pressure. The current overview presents the latest research findings on the mechanisms through which novel anti-hypertensive medications target the RAS. These include zilebesiran (targeting angiotensinogen), PRO20 (targeting the renin/(pro)renin/PRR axis), sacubitril/valsartan (targeting the renin/ACE/Ang II/AT1R axis), GSK2586881, Ang (1-7) and AVE0991 (targeting the renin/ACE2/Ang (1-7)/MasR axis), alamandine (targeting the alamandine/MrgD receptor axis), C21 and β-Pro7-Ang III (targeting the renin/ACE/Ang II/AT2R axis), EC33, and firibastat and NI956 (targeting brain Ang III).

Renal mitochondria response to sepsis: a sequential biopsy evaluation of experimental porcine model

BACKGROUND

The pathophysiology of sepsis-induced acute kidney injury remains elusive. Although mitochondrial dysfunction is often perceived as the main culprit, data from preclinical models yielded conflicting results so far. The aim of this study was to assess the immune-metabolic background of sepsis-associated renal dysfunction using sequential biopsy approach with mitochondria function evaluation in a large clinically relevant porcine models mimicking two different paces and severity of sepsis and couple this approach with traditional parameters of renal physiology.

METHODS

In this randomized, open-label study, 15 anaesthetized, mechanically ventilated and instrumented (renal artery flow probe and renal vein catheter) pigs were randomized in two disease severity groups-low severity (LS) sepsis (0.5 g/kg of autologous faeces intraperitoneally) and high severity (HS) sepsis (1 g/kg of autologous faeces intraperitoneally). Sequential cortical biopsies of the left kidney were performed and a pyramid-shaped kidney specimen with cortex, medulla and renal papilla was resected and processed at the end of the experiment. Oxygraphic data and western blot analysis of proteins involved in mitochondrial biogenesis and degradation were obtained.

RESULTS

In contrast to increased mitochondrial activity observed in LS sepsis, a significant decrease in the oxidative phosphorylation capacity together with an increase in the respiratory system uncoupling was observed during the first 24 h after sepsis induction in the HS group. Those changes preceded alterations of renal haemodynamics. Furthermore, serum creatinine rose significantly during the first 24 h, indicating that renal dysfunction is not primarily driven by haemodynamic changes. Compared to cortex, renal medulla had significantly lower oxidative phosphorylation capacity and electron-transport system activity. PGC-1-alfa, a marker of mitochondrial biogenesis, was significantly decreased in HS group.

CONCLUSIONS

In this experimental model, unique sequential tissue data show that the nature and dynamics of renal mitochondrial responses to sepsis are profoundly determined by the severity of infectious challenge and resulting magnitude of inflammatory insult. High disease severity is associated with early and stepwise progression of mitochondria dysfunction and acute kidney injury, both occurring independently from later renal macro-haemodynamic alterations. Our data may help explain the conflicting results of preclinical studies and suggest that sepsis encompasses a very broad spectrum of sepsis-induced acute kidney injury endotypes.

β-Caryophyllene attenuates oxidative stress and inflammatory response in LPS induced acute lung injury by targeting ACE2/MasR and Nrf2/HO-1/NF-κB axis

Acute lung injury (ALI) and its severe form, acute respiratory distress syndrome (ARDS), is a clinical syndrome that can cause pulmonary edema, inflammation, oxidative stress, and immunological dysregulations. β-Caryophyllene (BCP), a natural bicyclic sesquiterpene, possesses a variety of pharmacological properties and has the potential to be a therapeutic agent. This study aimed to comprehend the effect of BCP on Nrf2/HO-1/NF-κB and ACE2/MasR axis in a rat model of ALI by lipopolysaccharide (LPS) and the underlying mechanisms during this process. The study also examined pulmonary edema, BALF, and cytokine production to investigate inflammation and oxidative stress. In the LPS group, Western blot analysis showed decreased Nrf2/HO-1 and ACE2/MasR, including increased lung edema, elevated vascular permeability, neutrophil infiltration in BALF, increased cytokine levels, and histological changes. In comparison to the LPS group, BCP dramatically reduced lung edema, vascular permeability, and histological changes. Additionally, by lowering malondialdehyde and myeloperoxidase activity in lung tissues, it also reduced oxidative stress. BCP boosted IL-10 production and decreased the levels of pro-inflammatory cytokines and neutrophil infiltration. BCP administration decreased VEGF-A and SP-D expression, subsequently lowering NF-κB activation and cytokine production. Further, BCP altered ACE2 expression, indicating its involvement by activating the ACE2/Angiotensin (1-7)/MasR axis. In addition, BCP could stimulate the Nrf2/HO-1 anti-oxidant axis to suppress NF-κB and reduce inflammation. BCP modulation of the ACE2/MasR and Nrf2/HO-1/NF-κB axis impedes the course of ALI by influencing immunological response including but not limited to oxidative stress, the influx of neutrophils, and cytokine production. Hence, BCP may act as a potential candidate for management of ALI.

SARS-CoV-2 Spike Protein Amplifies the Immunogenicity of Healthy Renal Epithelium in the Presence of Renal Cell Carcinoma

Renal cell carcinoma (RCC) is the most common form of kidney cancer, known for its immune evasion and resistance to chemotherapy. Evidence indicates that the SARS-CoV-2 virus may worsen outcomes for RCC patients, as well as patients with diminished renal function. Evidence suggests that the SARS-CoV-2 virus may exacerbate outcomes in RCC patients and those with impaired renal function. This study explored the unidirectional effects of RCC cells and the SARS-CoV-2 spike protein (S protein) on human renal proximal tubule epithelial cells (RPTECs) using a microphysiological approach. We co-cultured RCC cells (Caki-1) with RPTEC and exposed them to the SARS-CoV-2 S protein under dynamic 3D conditions. The impact on metabolic activity, gene expression, immune secretions, and S protein internalization was evaluated. The SARS-CoV-2 S protein was internalized by RPTEC but poorly interacted with RCC cells. RPTECs exposed to RCC cells and the S protein exhibited upregulated expression of genes involved in immunogenic pathways, particularly those related to antigen processing and presentation via the major histocompatibility complex I (MHCI). Additionally, increased TNF-α secretion suggested a pro-inflammatory response. Metabolic shifts toward glycolysis were observed in RCC co-culture, while the presence of the S protein led to minor changes. The presence of RCC cells amplified the immune-modulatory effects of the SARS-CoV-2 S protein on the renal epithelium, potentially exacerbating renal inflammation and fostering tumor-supportive conditions. These findings suggest that COVID-19 infections can impact renal function in the presence of kidney cancer.

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.

Potential Nephroprotective Effect of uPA against Ischemia/Reperfusion-Induced Acute Kidney Injury in αMUPA Mice and HEK-293 Cells

Background/Objectives: The incidence of acute kidney injury (AKI) has been steadily increasing. Despite its high prevalence, there is no pathogenetically rational therapy for AKI. This deficiency stems from the poor understanding of the pathogenesis of AKI. Renal ischemia/hypoxia is one of the leading causes of clinical AKI. This study investigates whether αMUPA mice, overexpressing the urokinase plasminogen activator (uPA) gene are protected against ischemic AKI, thus unraveling a potential renal damage treatment target. Methods: We utilized an in vivo model of I/R-induced AKI in αMUPA mice and in vitro experiments of uPA-treated HEK-293 cells. We evaluated renal injury markers, histological changes, mRNA expression of inflammatory, apoptotic, and autophagy markers, as compared with wild-type animals. Results: the αMUPA mice exhibited less renal injury post-AKI, as was evident by lower SCr, BUN, and renal NGAL and KIM-1 along attenuated adverse histological alterations. Notably, the αMUPA mice exhibited decreased levels pro-inflammatory, fibrotic, apoptotic, and autophagy markers like TGF-β, IL-6, STAT3, IKB, MAPK, Caspase-3, and LC3. By contrast, ACE-2, p-eNOS, and PGC1α were higher in the kidneys of the αMUPA mice. In vitro results of the uPA-treated HEK-293 cells mirrored the in vivo findings. Conclusions: These results indicate that uPA modulates key pathways involved in AKI, offering potential therapeutic targets for mitigating renal damage.

C-reactive Protein (CRP) in Patients With Myocarditis: A Systematic Review and Meta-Analysis

Myocarditis is a type of cardiovascular disease related to inflammation of cardiac muscle which can be even fatal to some extent. Early and simple diagnosis is crucial for this complication; however, complex or machine-based methods, such as histological tests, x-rays, electrocardiograms, etc., are usually used for its detection. C-reactive protein (CRP) is a biomarker that naturally elevates during inflammation. Therefore, we tried to understand the correlation between CRP and myocarditis. We primarily identified 451 studies from PubMed, Google Scholar, and ScienceDirect and ultimately selected four studies as eligible. We identified the mean difference (MD) in CRP levels between the myocarditis patients and healthy controls. The study quality, outliers, sensitivity, significance, and heterogeneity were also checked. The MD (6.03 (95%CI: 2.41-9.64), p<0.00001) corresponds to a higher and significant CRP level in myocarditis as compared to the control group. The study quality was found to be high with no bias or outliers and the heterogeneity was also determined to be high (I2=99%). Using the fixed effect model, the forest plot determined a similar result as the main outcome (MD: 5.08 (95%CI: 4.85-5.32)) proving higher sensitivity and reproducibility. These findings indicated the possibility of CRP being an established biomarker for an accurate diagnosis and prognosis of myocarditis.

Targeting the epidermal growth factor receptor (EGFR/ErbB) for the potential treatment of renal pathologies

Epidermal growth factor receptor (EGFR), which is referred to as ErbB1/HER1, is the prototype of the EGFR family of receptor tyrosine kinases which also comprises ErbB2 (Neu, HER2), ErbB3 (HER3), and ErbB4 (HER4). EGFR, along with other ErbBs, is expressed in the kidney tubules and is physiologically involved in nephrogenesis and tissue repair, mainly following acute kidney injury. However, its sustained activation is linked to several kidney pathologies, including diabetic nephropathy, hypertensive nephropathy, glomerulonephritis, chronic kidney disease, and renal fibrosis. This review aims to provide a summary of the recent findings regarding the consequences of EGFR activation in several key renal pathologies. We also discuss the potential interplay between EGFR and the reno-protective angiotensin-(1-7) (Ang-(1-7), a heptapeptide member of the renin-angiotensin-aldosterone system that counter-regulates the actions of angiotensin II. Ang-(1-7)-mediated inhibition of EGFR transactivation might represent a potential mechanism of action for its renoprotection. Our review suggests that there is a significant body of evidence supporting the potential inhibition of EGFR/ErbB, and/or administration of Ang-(1-7), as potential novel therapeutic strategies in the treatment of renal pathologies. Thus, EGFR inhibitors such as Gefitinib and Erlinotib that have an acceptable safety profile and have been clinically used in cancer chemotherapy since their FDA approval in the early 2000s, might be considered for repurposing in the treatment of renal pathologies.

Ultrasmall Polyphenol-NAD+ Nanoparticle-Mediated Renal Delivery for Mitochondrial Repair and Anti-Inflammatory Treatment of AKI-to-CKD Progression

As a central metabolic molecule, nicotinamide adenine dinucleotide (NAD+) can potentially treat acute kidney injury (AKI) and chronic kidney disease (CKD); however, its bioavailability is poor due to short half-life, instability, the deficiency of targeting, and difficulties in transmembrane transport. Here a physiologically adaptive gallic acid-NAD+ nanoparticle is designed, which has ultrasmall size and pH-responsiveness, passes through the glomerular filtration membrane to reach injured renal tubules, and efficiently delivers NAD+ into the kidneys. With an effective accumulation in the kidneys, it restores renal function, immune microenvironment homeostasis, and mitochondrial homeostasis of AKI mice via the NAD+-Sirtuin-1 axis, and exerts strong antifibrotic effects on the AKI-to-CKD transition by inhibiting TGF-β signaling. It also exhibits excellent stability, biodegradable, and biocompatible properties, ensuring its long-term safety, practicality, and clinical translational feasibility. The present study shows a potential modality of mitochondrial repair and immunomodulation through nanoagents for the efficient and safe treatment of AKI and CKD.

Urinary angiotensin-converting enzyme 2 and its activity in cats with chronic kidney disease

Introduction

Angiotensin-converting enzyme 2 (ACE2) played an important role in the renin-angiotensin-aldosterone system (RAAS) and it was proved to be renoprotective in renal disease. Urinary angiotensin-converting enzyme 2 (uACE2) has been shown to reflect renal injury in human and experimental studies, but its role in feline kidney disease remains unknown.

Aims

Our objectives involve comparing uACE2 concentrations and activities in cats across CKD stages with healthy controls, investigating the relationship between uACE2 concentrations, activities, and clinicopathological data in feline CKD patients, and assessing the predictive abilities of both for CKD progression.

Methods

A retrospective, case-control study. The concentration and activity of uACE2 were measured by commercial ELISA and fluorometric assay kits, respectively. The concentration was adjusted to give uACE2 concentration-to-creatinine ratios (UACCRs).

Results

In total, 67 cats consisting of 24 control and 43 chronic kidney disease (CKD), including 24 early-stage CKD and 19 late-stage CKD, were enrolled in this study. UACCR values were significantly higher in both early-stage (2.100 [1.142-4.242] x 10-6) and late-stage feline CKD (4.343 [2.992-5.0.71] x 10-6) compared to healthy controls (0.894 [0.610-1.076] x 10-6; p < 0.001), and there was also significant difference between-early stage group and late-stage group (p = 0.026). Urinary ACE2 activity (UAA) was significantly lower in CKD cats (1.338 [0.644-2.755] x pmol/min/ml) compared to the healthy cats (7.989 [3.711-15.903] x pmol/min/ml; p < 0.001). UACCR demonstrated an independent, positive correlation with BUN (p < 0.001), and UAA exhibited an independent, negative correlation with plasma creatinine (p < 0.001). Both UACCR and UAA did not yield significant results in predicting CKD progression based on the ROC curve analysis.

Conclusion and clinical importance

uACE2 concentration and activity exhibit varying changes as renal function declines, particularly in advanced CKD cats.

The Fatty Liver Index's Association with Incident Chronic Kidney Disease in Korean Middle-Aged Adults: A Community-Based Cohort Study

(1) Background: The relationship between nonalcoholic fatty liver disease (NAFLD) and incident chronic kidney disease (CKD) is unclear, and long-term follow-up data are limited. Therefore, this study aimed to evaluate whether NAFLD, as assessed by the fatty liver index (FLI), could predict the development of CKD in a community-based Korean cohort over 16 years. (2) Methods: Among the 10,030 total participants, 7778 patients without CKD were selected from the Korean Genome and Epidemiology Study (KoGES). The FLI grade ranged from 0 to 100 and was divided into three groups: low (FLI, <30), intermediate (FLI, 30-59), and high (FLI, ≥60). An estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73 m2 or the development of proteinuria was considered to indicate incident CKD. (3) Results: During the 16-year follow-up period, 919 individuals (11.8%) developed CKD. The HRs of incident CKD in the intermediate FLI group (30-59) and high FLI group (≥60) increased compared with the reference low FLI group (<30) after adjusting for potentially confounding variables. NAFLD, as assessed by the FLI, was an independent risk factor for CKD. (4) Conclusions: Our findings suggest that the FLI, a simple surrogate biomarker of fatty liver disease, may be used to identify people at high risk of incident CKD in clinical practice.

Comprehensive strategy for identifying extracellular vesicle surface proteins as biomarkers for chronic kidney disease

Chronic kidney disease (CKD) poses a significant health burden worldwide. Especially, obesity-induced chronic kidney disease (OCKD) is associated with a lack of accuracy in disease diagnostic methods. The identification of reliable biomarkers for the early diagnosis and monitoring of CKD and OCKD is crucial for improving patient outcomes. Extracellular vesicles (EVs) have emerged as potential biomarkers in the context of CKD. In this review, we focused on the role of EVs as potential biomarkers in CKD and OCKD and developed a comprehensive list of EV membrane proteins that could aid in the diagnosis and monitoring of the disease. To assemble our list, we employed a multi-step strategy. Initially, we conducted a thorough review of the literature on EV protein biomarkers in kidney diseases. Additionally, we explored papers investigating circulating proteins as biomarkers in kidney diseases. To further refine our list, we utilized the EV database Vesiclepedia.org to evaluate the qualifications of each identified protein. Furthermore, we consulted the Human Protein Atlas to assess the localization of these candidates, with a particular focus on membrane proteins. By integrating the information from the reviewed literature, Vesiclepedia.org, and the Human Protein Atlas, we compiled a comprehensive list of potential EV membrane protein biomarkers for CKD and OCKD. Overall, our review underscores the potential of EVs as biomarkers in the field of CKD research, providing a foundation for future studies aimed at improving CKD and OCKD diagnosis and treatment.

Review on Kidney-Liver Crosstalk: Pathophysiology of Their Disorders

Kidney-liver crosstalk plays a crucial role in normal and certain pathological conditions. In pathologic states, both renal-induced liver damage and liver-induced kidney diseases may happen through these kidney-liver interactions. This bidirectional crosstalk takes place through the systemic conditions that mutually influence both the liver and kidneys. Ischemia and reperfusion, cytokine release and pro-inflammatory signaling pathways, metabolic acidosis, oxidative stress, and altered enzyme activity and metabolic pathways establish the base of this interaction between the kidneys and liver. In these concomitant kidney-liver diseases, the survival rates strongly correlate with early intervention and treatment of organ dysfunction. Proper care of a nephrologist and hepatologist and the identification of pathological conditions using biomarkers at early stages are necessary to prevent the complications induced by this complex and potentially vicious cycle. Therefore, understanding the characteristics of this crosstalk is essential for better management. In this review, we discussed the available literature concerning the detrimental effects of kidney failure on liver functions and liver-induced kidney diseases.

Significance of Chronic Kidney Disease on Morbidity and Mortality in Hospitalized Patients With COVID-19

Background

Patients with comorbid illnesses are at risk for worse outcomes with a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2; COVID-19). Our research examined patients with chronic kidney disease (CKD) to establish whether it remains an independent risk factor for mortality and morbidity in patients with COVID-19.

Methods

We conducted a retrospective cohort study using an electronic patient database in 2020. An observational dataset from 149 hospitals comprising a United States-based health system (HCA Healthcare) was analyzed. Hospitalized patients (N=11 086), aged 18 and above, with a COVID-19 polymerase chain reaction positive result between January 1, 2020, and September 1, 2020, were included in the initial data set.Primary outcomes were in-hospital death or discharge to hospice in patients with COVID-19. Secondary outcomes were individual components of the primary outcome including intensive care unit (ICU) admission, ventilator dependency, development of acute kidney injury (AKI), and in-hospital death. Baseline patient characteristics were recorded, including demographic variables and comorbidities.

Results

A total of 11 086 patients were included in the analysis. The study group included patients with CKD (5543 patients). Patients in the control group (5543 patients) were propensity matched for age, race, sex, and ethnicity. The primary outcome of in-hospital death or discharge to hospice was observed in 20.96% of patients with CKD compared to 11.91% of the control group with an odds ratio of 1.58 (confidence interval 1.37-1.80). ICU admission was required for 37.20% of patients in the CKD group and 21.63% of patients in the control group (P < .001). Ventilator dependency was found in 14.41% of patients in the CKD group and 8.59% of patients in the control group (P < .01). Development of AKI was seen in 5.65% of patients in the CKD group and 2.90% of patients in the control group (P < .01). A logistic regression model confirmed an independent association between underlying CKD and in-hospital death or discharge to hospice in patients with COVID-19.

Conclusion

Our study confirms an independent association between underlying CKD and poor outcomes among hospitalized patients with COVID-19, including in-hospital death or discharge to hospice.

New Insights into the Link between SARS-CoV-2 Infection and Renal Cancer

Cancer has been described as a risk factor for greater susceptibility to SARS-CoV-2 infection and severe COVID-19, mainly for patients with metastatic disease. Conversely, to that reported for most solid and hematological malignancies, the few available clinical studies reported that the infection did not increase the risk of death in renal cancer patients. The expression on proximal tubular renal cells of the key players in cellular viral uptake, ACE2, TMPRSS2, and NRP1, seems to be the mechanism for the direct kidney injury seen in patients with COVID-19. Interestingly, data from The Cancer Genome Atlas and experimental analyses on various renal cancer cell lines demonstrated that the above-reported receptors/cofactors are maintained by renal cancer cells. However, whether SARS-CoV-2 infection directly kills renal cancer cells or generates enhanced immunogenicity is a question worth investigating. In addition, some researchers have further addressed the topic by studying the expression and prognostic significance of gene signatures related to SARS-CoV-2 infection in renal cancer patients. The emerging data highlights the importance of better understanding the existence of a link between renal cancer and COVID-19 since it could lead to the identification of new prognostic factors and the development of new therapeutic targets in the management of renal cancer patients.

Studying the Roles of the Renin-Angiotensin System in Accelerating the Disease of High-Fat-Diet-Induced Diabetic Nephropathy in a db/db and ACE2 Double-Gene-Knockout Mouse Model

Diabetic nephropathy (DN) is a crucial metabolic health problem. The renin-angiotensin system (RAS) is well known to play an important role in DN. Abnormal RAS activity can cause the over-accumulation of angiotensin II (Ang II). Angiotensin-converting enzyme inhibitor (ACEI) administration has been proposed as a therapy, but previous studies have also indicated that chymase, the enzyme that hydrolyzes angiotensin I to Ang II in an ACE-independent pathway, may play an important role in the progression of DN. Therefore, this study established a model of severe DN progression in a db/db and ACE2 KO mouse model (db and ACE2 double-gene-knockout mice) to explore the roles of RAS factors in DNA and changes in their activity after short-term (only 4 weeks) feeding of a high-fat diet (HFD) to 8-week-old mice. The results indicate that FD-fed db/db and ACE2 KO mice fed an HFD represent a good model for investigating the role of RAS in DN. An HFD promotes the activation of MAPK, including p-JNK and p-p38, as well as the RAS signaling pathway, leading to renal damage in mice. Blocking Ang II/AT1R could alleviate the progression of DN after administration of ACEI or chymase inhibitor (CI). Both ACE and chymase are highly involved in Ang II generation in HFD-induced DN; therefore, ACEI and CI are potential treatments for DN.

Mendelian randomization indicates causal effects of estradiol levels on kidney function in males

Context

Chronic kidney disease (CKD) is a public health burden worldwide. Epidemiological studies observed an association between sex hormones, including estradiol, and kidney function.

Objective

We conducted a Mendelian randomization (MR) study to assess a possible causal effect of estradiol levels on kidney function in males and females.

Design

We performed a bidirectional two-sample MR using published genetic associations of serum levels of estradiol in men (n = 206,927) and women (n = 229,966), and of kidney traits represented by estimated glomerular filtration rate (eGFR, n = 567,460), urine albumin-to-creatinine ratio (UACR, n = 547,361), and CKD (n = 41,395 cases and n = 439,303 controls) using data obtained from the CKDGen Consortium. Additionally, we conducted a genome-wide association study using UK Biobank cohort study data (n = 11,798 men and n = 6,835 women) to identify novel genetic associations with levels of estradiol, and then used these variants as instruments in a one-sample MR.

Results

The two-sample MR indicated that genetically predicted estradiol levels are significantly associated with eGFR in men (beta = 0.077; p = 5.2E-05). We identified a single locus at chromosome 14 associated with estradiol levels in men being significant in the one-sample MR on eGFR (beta = 0.199; p = 0.017). We revealed significant results with eGFR in postmenopausal women and with UACR in premenopausal women, which did not reach statistical significance in the sensitivity MR analyses. No causal effect of eGFR or UACR on estradiol levels was found.

Conclusions

We conclude that serum estradiol levels may have a causal effect on kidney function. Our MR results provide starting points for studies to develop therapeutic strategies to reduce kidney disease.

Increased Estimated GFR Is Negatively Associated With the Risk of SARS-CoV-2 Infection and Severe COVID-19 Within Normal to Mildly Decreased Levels: Nested Case-Control Study

BACKGROUND

While accumulating evidence indicates chronic kidney disease as a risk factor for coronavirus disease 2019 (COVID-19), the association between normal or mildly decreased kidney function and COVID-19 is unaddressed. Here, we have examined the association of an increase in estimated glomerular filtration rate (eGFR) with the incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and severe COVID-19 outcomes among patients within normal to mildly decreased kidney function.

METHODS

The patients who participated in both health screenings from period I (2017-2018) to II (2019-2020) were enrolled to our study. All participants were categorized into four groups according to the changes in eGFR stage from period I to II: 1) persistently stage G1, 2) from stage G2 to G1, 3) from stage G1 to G2, 4) persistently stage G2. In addition, the changes in eGFR value were defined by subtracting its value of period I from II. Patients were followed up for SARS-CoV-2 infection from January 1, 2021 to any diagnosis of COVID-19 or December 31, 2021, whichever happened first. In addition, those with SARS-CoV-2 infection were followed-up for one month after diagnosis to analyze severe COVID-19. Adjusted odds ratio (aOR) was calculated using multivariable-adjusted logistic regression.

RESULTS

We identified 159,427 patients with and 1,804,798 patients without SARS-CoV-2 infection. The risk of SARS-CoV-2 infection decreased when eGFR stage changed from G2 to G1 (aOR, 0.957; 95% confidence interval [CI], 0.938-0.977) and persistently maintained at G1 (aOR, 0.966; 95% CI, 0.943-0.990), compared with the persistently stage G2 group. In addition, the risk showed an inverse relationship with changes in eGFR value, which was depicted by restricted cubic spline curves. For the overall risk of severe COVID-19, the persistently stage G1 showed the lowest risk (aOR, 0.897; 95% CI, 0.827-0.972), followed by those from stage G1 to G2 (aOR, 0.900; 95% CI, 0.828-0.978) and those from stage G2 to G1 (aOR, 0.931; 95% CI, 0.871-0.995), compared with the persistently stage G2 group.

CONCLUSION

An increase in eGFR was negatively associated with the risk of SARS-CoV-2 infection and severe COVID-19 among normal or mildly decreased kidney function. For severe COVID-19, maintaining higher baseline eGFR may act as a protective factor against its risk.

Nephroprotective effects of diminazene on doxorubicin-induced acute kidney injury in rats

This study aimed to investigate the potential protective effects of diminazene, an activator of angiotensin II converting enzyme (ACE2), on kidney function and structure in rats with acute kidney injury (AKI) induced by the anticancer drug doxorubicin (DOX). The impact of diminazene was compared to that of two other drugs: the ACE inhibitor lisinopril and the angiotensin II type 1 (AT1) receptor blocker valsartan. Rats were subjected to a single intraperitoneal injection of DOX (13.5 mg/kg) on the 5th day, either alone or in combination with diminazene (15 mg/kg/day), lisinopril (10 mg/kg/day), or valsartan (30 mg/kg/day) for 8 consecutive days. Various markers related to kidney function, oxidative stress, and inflammation were measured in plasma and urine. Additionally, kidney tissues were assessed histopathologically. DOX-induced nephrotoxicity was confirmed by elevated levels of plasma urea, creatinine, and neutrophil gelatinase-associated lipocalin (NGAL). DOX also led to increased urinary N-acetyl-β-D-glucosaminidase (NAG) activity and decreased creatinine clearance, albumin levels, and osmolality. Moreover, DOX caused a reduction in renal oxidative stress markers, including superoxide dismutase (SOD), glutathione reductase (GR), and catalase activities, while increasing malondialdehyde (MDA) levels. It also raised plasma inflammatory markers, tumor necrosis factor alpha (TNF-α) and interleukin 1 beta (IL-1β). Concurrently administering diminazene significantly mitigated these DOX-induced changes, including histopathological alterations like renal tubule necrosis, tubular casts, shrunken glomeruli, and increased renal fibrosis. Similar protective effects were observed with lisinopril and valsartan. These protective effects, at least in part, appear to result from the anti-inflammatory and antioxidant properties of these drugs. In summary, this study suggests that the administration of diminazene, lisinopril, or valsartan had comparable effects in ameliorating the biochemical and histopathological aspects of DOX-induced acute kidney injury in rats.

Catecholamine Vasopressor Exposure Is Associated With Early Poor Allograft Function and Adverse Events in Living Donor Kidney Transplant Recipients

BACKGROUND

Hypoperfusion leads to allograft injury during kidney transplantation. Catecholamine vasopressors are used to maintain blood pressure in the perioperative period but have demonstrated negative outcomes in the deceased-donor kidney transplant population. Little is known regarding living donor kidney transplants (LDKTs) and vasopressor use. The aim of this study is to describe the incidence of vasopressor use in LDKT and characterize its effects on allograft function and patient outcomes.

METHODS

This retrospective, observational cohort study included adult patients who underwent an isolated LDKT between August 1, 2017, and September 1, 2018. Patients were divided into those who received perioperative vasopressors and those who did not. The primary objective was to compare allograft function between LDKT recipients that received vasopressors and those who did not. Secondary outcomes included safety endpoints and the identification of clinical variables associated with vasopressor use.

RESULTS

A total of 67 patients received an LDKT during the study period. Of those, 25 (37%) received perioperative vasopressors, and 42 (62%) did not. Poor graft function, as defined by the development of slow or delayed graft function, occurred more frequently in patients receiving perioperative vasopressors compared with those who did not (6 [24%] vs 1 [2.4%], P = .016). In multivariable regression modeling, only perioperative vasopressors were statistically significantly associated with poor graft function. In addition, patients exposed to vasopressors experienced more postoperative arrhythmias (8 [32%] vs 1 [4.8%], P = .0025).

CONCLUSION

Using perioperative vasopressors was independently associated with worsened early renal allograft function, including delayed graft function and adverse events in the LDKT population.

ACE2 and a Traditional Chinese Medicine Formula NRICM101 Could Alleviate the Inflammation and Pathogenic Process of Acute Lung Injury

COVID-19 is a highly transmittable respiratory illness caused by SARS-CoV-2, and acute lung injury (ALI) is the major complication of COVID-19. The challenge in studying SARS-CoV-2 pathogenicity is the limited availability of animal models. Therefore, it is necessary to establish animal models that can reproduce multiple characteristics of ALI to study therapeutic applications. The present study established a mouse model that has features of ALI that are similar to COVID-19 syndrome to investigate the role of ACE2 and the administration of the Chinese herbal prescription NRICM101 in ALI. Mice with genetic modifications, including overexpression of human ACE2 (K18-hACE2 TG) and absence of ACE2 (mACE2 KO), were intratracheally instillated with hydrochloric acid. The acid intratracheal instillation induced severe immune cell infiltration, cytokine storms, and pulmonary disease in mice. Compared with K18-hACE2 TG mice, mACE2 KO mice exhibited dramatically increased levels of multiple inflammatory cytokines (IL-6 and TNF-α) in bronchoalveolar lavage fluid, histological evidence of lung injury, and dysregulation of MAPK and MMP activation. In mACE2 KO mice, NRICM101 could ameliorate the disease progression of acid-induced ALI. In conclusion, the established mouse model provided an effective platform for researchers to investigate pathological mechanisms and develop therapeutic strategies for ALI, including COVID-19-related ALI.

All-trans retinoic acid inhibits oxidative stress via ACE2/Ang (1-7)/MasR pathway in renal tubular epithelial cells stimulated with high glucose

The aim of this study was to investigate the effects of all-trans retinoic acid (atRA) on oxidative stress in renal tubular epithelial cells induced by high glucose (HG) and its potential mechanism. We investigated the effects of atRA in HG-induced renal epithelial cell line HK-2. Seven groups were designed for this experiment: negative control, mannitol, high-glucose (HG), HG combined with a low concentration of atRA, HG combined with a middle concentration of atRA, HG combined with a high concentration of atRA, and HG combined with captopril. After 48 h of incubation, oxidative stress factor expression in the supernatant was detected by enzyme-linked immunosorbent assay. Reactive oxygen species and cell apoptosis expression were assessed by flow cytometry. NADPH oxidase, fibrosis factor, and angiotensin-converting enzyme 2/angiotensin (1-7)/mas receptor (ACE2/Ang (1-7)/MasR) pathway-related protein expressions were determined by western blot analysis. The expressions of oxidative stress factors, NADPH oxidase components, and fibrosis factors were significantly higher after HG treatment. Apoptosis of HK2 cells in the HG group was also significantly higher. AtRA could reverse the above abnormal changes in a concentration-dependent manner. HG significantly promoted the expression of ACE, Ang II, and Ang II type 1 receptor (AT1R), whereas it inhibited the expression of ACE2, Ang (1-7), and MasR. With the elevation of concentration, atRA could gradually suppress the expression of ACE, Ang II, and AT1R, but facilitate ACE2, Ang (1-7), and MasR. These results were statistically significant. AtRA could significantly inhibit oxidative stress and apoptosis of renal tubular epithelial cells induced by HG. The mechanism may inhibit the ACE/Ang II/AT1R pathway and/or activate ACE2/Ang (1-7)/MasR pathway.

Nonalcoholic Fatty Liver Disease and Chronic Kidney Disease Cross Talk

Nonalcoholic fatty liver disease is a multisystem condition with effects beyond the liver. The identification of chronic kidney disease as an independent mediator of nonalcoholic fatty liver disease or associated entity with shared cardiometabolic risk factors remains controversial and continues to draw scientific interest. With increasing prevalence of nonalcoholic fatty liver disease and lack of Food and Drug Administration approved therapies, these shared cardiometabolic risk factors have drawn significant attention. In this article, we review shared pathophysiological mechanisms between nonalcoholic fatty liver disease and chronic kidney disease along with current treatment strategies that might be useful for both disease processes.

Ang-(1-7) attenuates podocyte injury induced by high glucose in vitro

Objective

The incidence of diabetic nephropathy (DN) is gradually increasing worldwide. Podocyte injury, such as podocyte apoptosis and loss of the slit diaphragm (SD)-specific markers are early pathogenic features of DN.

Materials and methods

The cultured mouse podocytes were separated into a high glucose-treated (HG, 30mM) group to mimic DN in vitro, a low glucose-treated (LG, 5mM) group as a control and HG+ angiotensin-(1-7)(Ang-(1-7)) and HG+Ang-(1-7) + D-Ala7-Ang-(1-7) (A779, Ang-(1-7)/Mas receptor antagonist) experimental groups. The Cell Counting Kit-8 (CCK-8) method and flow cytometry was used to detect podocyte activity and podocyte apoptosis respectively. The expression of angiotensin type 1 receptor (AT1R), Mas receptor (MasR) and podocyte-specific markers were examined by q-PCR and Western blot, respectively.

Results

The results showed that the decrease in podocyte activity; the increase in podocyte apoptosis; the decreased mRNA and protein expression of nephrin, podocin, WT-1 and MasR; and the upregulated expression of AT1R induced by HG could be reversed by Ang-(1-7). However, these effects were blocked by A779. The possible mechanisms of the Ang-(1-7)-mediated effect depended on MasR. In addition, the protective effect of Ang-(1-7) on podocyte activity was dose-dependent and most obvious at 10 µM. A779 had the greatest antagonistic action against Ang-(1-7) at a concentration of 10 μM.

Conclusion

This study reveals that binding of Ang-(1-7) to its specific receptor MasR may counteract the effects of Ang II mediated by AT1R to significantly attenuate podocyte injury induced by high glucose. Ang-(1-7)/MasR targeting in podocytes may be a therapeutic approach to attenuate renal injury in DN.

Integrin β1 is a key determinant of the expression of angiotensin-converting enzyme 2 (ACE2) in the kidney epithelial cells

The expression of the angiotensin-converting enzyme 2 (ACE2) is altered in multiple chronic kidney diseases like hypertension and renal fibrosis, where the signaling from the basal membrane proteins is critical for the development and progression of the various pathologies. Integrins are heterodimeric cell surface receptors that have important roles in the progression of these chronic kidney diseases by altering various cell signaling pathways in response to changes in the basement membrane proteins. It is unclear whether integrin or integrin-mediated signaling affects the ACE2 expression in the kidney. The current study tests the hypothesis that integrin β1 regulates the expression of ACE2 in kidney epithelial cells. The role of integrin β1 in ACE2 expression in renal epithelial cells was investigated by shRNA-mediated knockdown and pharmacological inhibition. In vivo studies were carried out using epithelial cell-specific deletion of integrin β1 in the kidneys. Deletion of integrin β1 from the mouse renal epithelial cells reduced the expression of ACE2 in the kidney. Furthermore, the downregulation of integrin β1 using shRNA decreased ACE2 expression in human renal epithelial cells. ACE2 expression levels were also decreased in renal epithelial cells and cancer cells when treated with an integrin α2β1 antagonist, BTT 3033. SARS-CoV-2 viral entry to human renal epithelial cells and cancer cells was also inhibited by BTT 3033. This study demonstrates that integrin β1 positively regulates the expression of ACE2, which is required for the entry of SARS-CoV-2 into kidney cells.

Identification of the regulatory mechanism of ACE2 in COVID-19-induced kidney damage with systems genetics approach

Studies showed that SARS-CoV-2 can directly target the kidney and induce renal damage. As the cell surface receptor for SARS-CoV-2 infection, the angiotensin-converting enzyme 2 (ACE2) plays a pivotal role for renal physiology and function. Thus, it is important to understand ACE2 through which pathway influences the pathogenesis of renal damage induced by COVID-19. In this study, we first performed an eQTL mapping for Ace2 in kidney tissues in 53 BXD mice strains. Results demonstrated that Ace2 is highly expressed and strongly controlled by a genetic locus on chromosome 16 in the kidney, with six genes (Dnase1, Vasn, Usp7, Abat, Mgrn1, and Rbfox1) dominated as the upstream modulator, as they are highly correlated with Ace2 expression. Gene co-expression analysis showed that Ace2 co-variates are significantly involved in the renin-angiotensin system (RAS) pathway which acts as a reno-protector. Importantly, we also found that Ace2 is positively correlated with Pdgf family members, particularly Pdgfc, which showed the most association among the 76 investigated growth factors. Mammalian Phenotype Ontology enrichment indicated that the cognate transcripts for both Ace2 and Pdgfc were mainly involved in regulating renal physiology and morphology. Among which, Cd44, Egfr, Met, Smad3, and Stat3 were identified as hub genes through protein-protein interaction analysis. Finally, in aligning with our systems genetics findings, we found ACE2, pdgf family members, and RAS genes decreased significantly in the CAKI-1 kidney cancer cells treated with S protein and receptor binding domain structural protein. Collectively, our data suggested that ACE2 work with RAS, PDGFC, as well as their cognate hub genes to regulate renal function, which could guide for future clinical prevention and targeted treatment for COVID-19-induced renal damage outcomes. KEY MESSAGES: • Ace2 is highly expressed and strongly controlled by a genetic locus on chromosome 16 in the kidney. • Ace2 co-variates are enriched in the RAS pathway. • Ace2 is strongly correlated with the growth factor Pdgfc. • Ace2 and Pdgfc co-expressed genes involved in the regulation of renal physiology and morphology. • SARS-CoV-2 spike glycoprotein induces down-regulation of Ace2, RAS, and Pdgfc.

Exploring the Role of ACE2 as a Connecting Link between COVID-19 and Parkinson's Disease

Coronavirus disease 2019 (COVID-19) is frequently accompanied by neurological manifestations such as headache, delirium, and epileptic seizures, whereas ageusia and anosmia may appear before respiratory symptoms. Among the various neurological COVID-19-related comorbidities, Parkinson's disease (PD) has gained increasing attention. Some cases of PD disease have been linked to COVID-19, and both motor and non-motor symptoms in Parkinson's disease patients frequently worsen following SARS-CoV-2 infection. Although it is still unclear whether PD increases the susceptibility to SARS-CoV-2 infection or whether COVID-19 increases the risk of or unmasks future cases of PD, emerging evidence sheds more light on the molecular mechanisms underlying the relationship between these two diseases. Among them, angiotensin-converting enzyme 2 (ACE2), a significant component of the renin-angiotensin system (RAS), seems to play a pivotal role. ACE2 is required for the entry of SARS-CoV-2 to the human host cells, and ACE2 dysregulation is implicated in the severity of COVID-19-related acute respiratory distress syndrome (ARDS). ACE2 imbalance is implicated in core shared pathophysiological mechanisms between PD and COVID-19, including aberrant inflammatory responses, oxidative stress, mitochondrial dysfunction, and immune dysregulation. ACE2 may also be implicated in alpha-synuclein-induced dopaminergic degeneration, gut-brain axis dysregulation, blood-brain axis disruption, autonomic dysfunction, depression, anxiety, and hyposmia, which are key features of PD.

ACE2-Inhibitory Effects of Bromelain and Ficin in Colon Cancer Cells

Background and Objectives: Bromelain and ficin are aqueous extracts from fruits of Ananas comosus and Ficus carcia plants, used widely for medical applications. Angiotensin-converting enzyme 2 (ACE2) is a homolog of ACE, degrading Ang II to angiotensin 1-7 and decreasing the cellular concentration of Ang II. Materials and Methods: In this study, we investigated the ACE2-inhibitory, antiproliferative, and apoptosis-inducing effects of ficin and bromelain on caco-2 cells. Results: We found that bromelain and ficin significantly reduced the viability of human colon cancer cells with IC₅₀ value concentrations of 8.8 and 4.2 mg/mL for bromelain after 24 and 48 h treatments, and 8.8 and 4.2 mg/mL for ficin after 24 and 48 h treatments, respectively. The apoptosis of the caco-2 cell line treated with bromelain was 81.04% and 56.70%, observed after 24 and 48 h. Total apoptotic proportions in caco-2 cells treated with ficin after 24 and 48 h were 83.7% and 73.0%. An amount of 1.6 mg/mL of bromelain and ficin treatments on caco-2 cells after 24 h revealed a higher decrease than that of other concentrations in the expression of ACE2 protein. Conclusions: In conclusion, bromelain and ficin can dose-dependently decrease the expression of ACE2 protein in caco-2 cells.

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.

The association between liver fibrosis scores and chronic kidney disease

Purpose

This study aimed to clarify the relationship between liver fibrosis scores (Fibrosis-4, BARD score, and BAAT score) and chronic kidney disease (CKD).

Methods

We collected a range of data from 11,503 subjects (5,326 men and 6,177 women) from the rural regions of Northeastern China. Three liver fibrosis scores (LFSs) including fibrosis-4 (FIB-4), BARD score, and BAAT score were adopted. A logistic regression analysis was used to calculate odds ratios and the 95% confidence interval. A subgroup analysis showed the association between LFSs and CKD under different stratifications. Restricted cubic spline could further explore whether there is a linear relationship between LFSs and CKD. Finally, we used C-statistics, Net Reclassification Index (NRI), and Integrated Discrimination Improvement (IDI) to assess the effect of each LFS on CKD.

Results

Through the baseline characteristics, we observed that LFSs were higher in the CKD population than in non-CKD. The proportion of participants with CKD also increased with LFSs. In a multivariate logistic regression analysis, the ORs of CKD were 6.71 (4.45-10.13) in FIB-4, 1.88 (1.29-2.75) in the BAAT score, and 1.72 (1.28-2.31) in the BARD score by comparing the high level with the low level in each LFSs. Moreover, after adding LFSs to the original risk prediction model, which consisted of age, sex, drinking, smoking, diabetes, low-density lipoprotein cholesterol, total cholesterol, triglycerides, and mean waist circumference, we found the new models have higher C-statistics. Furthermore, NRI and IDI both indicate LFSs had a positive effect on the model.

Conclusions

Our study showed that LFSs are associated with CKD among middle-aged populations in rural areas of northeastern China.

Endosulfan induced kidney cell injury by modulating ACE2 through up-regulating miR-429 in HK-2 cells

Endosulfan, a typical organochlorine pesticide, is widely used in agricultural countries and was detected in blood samples from the general population. Studies have shown a positive correlation between chronic kidney disease of unknown aetiology (CKDu) and endosulfan. CKDu has become endemic in agricultural countries, with clinical manifestations of tubulointerstitial fibrosis.The goal of this study was to investigate the effects of endosulfan in kidney cell injury in human renal tubular epithelial cells (HK-2), focusing on apoptosis, inflammatory response, and epithelial-mesenchymal transition (EMT). We found that endosulfan induced apoptosis in HK-2 cells by up-regulating the expression of BAX, APAF-1, Caspase-3 and mitochondrial Cytochrome c was released into the cytosol. Endosulfan caused an inflammatory response, showing the increase in the secretion and mRNA expression levels of IL-6/IL-8. Endosulfan triggered EMT, characterized by downregulation of E-cadherin and upregulation of Vimentin. Western blot results showed that p-Smad3 and Smad3 protein expression were elevated while the expression of Smad7 were decreased in endosulfan-exposed groups. Dual luciferase reporter assay confirmed the potential binding capacity of miR-429 to 3'-UTR of ACE2. Endosulfan causes upregulation of miR-429 and downregulation of ACE2 in HK-2 cells. Overexpression of miR-429 or silencing of ACE2 in HK-2 cells caused apoptosis, inflammation and EMT through TGF signaling pathway. These findings suggest that endosulfan can lead to kidney cell injury by modulating ACE2 through up-regulating miR-429, providing new evidence for the pathogenesis of CKDu.

COVID-19 and Acute Kidney Injury - Direct and Indirect Pathophysiological Mechanisms Underlying Lesion Development

COVID-19 is a pandemic disease caused by the SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) responsible for millions of deaths worldwide. Although the respiratory system is the main target of COVID-19, the disease can affect other organs, including the kidneys. Acute Kidney Injury (AKI), commonly seen in patients infected with COVID-19, has a multifactorial cause. Several studies associate this injury with the direct involvement of the virus in renal cells and the indirect damage stimulated by the infection. The direct cytopathic effects of SARS-CoV-2 are due to the entry and replication of the virus in renal cells, changing several regulatory pathways, especially the renin-angiotensin-aldosterone system (RAAS), with repercussions on the kallikrein-kinin system (KKS). Furthermore, the virus can deregulate the immune system, leading to an exaggerated response of inflammatory cells, characterizing the state of hypercytokinemia. The such exaggerated inflammatory response is commonly associated with hemodynamic changes, reduced renal perfusion, tissue hypoxia, generation of reactive oxygen species (ROS), endothelial damage, and coagulopathies, which can result in severe damage to the renal parenchyma. Thereby, understanding the molecular mechanisms and pathophysiology of kidney injuries induced by SARS-COV-2 is of fundamental importance to obtaining new therapeutic insights for the prevention and management of AKI.

Human lungs show limited permissiveness for SARS-CoV-2 due to scarce ACE2 levels but virus-induced expansion of inflammatory macrophages

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) utilises the angiotensin-converting enzyme 2 (ACE2) transmembrane peptidase as cellular entry receptor. However, whether SARS-CoV-2 in the alveolar compartment is strictly ACE2-dependent and to what extent virus-induced tissue damage and/or direct immune activation determines early pathogenesis is still elusive.

METHODS

Spectral microscopy, single-cell/-nucleus RNA sequencing or ACE2 "gain-of-function" experiments were applied to infected human lung explants and adult stem cell derived human lung organoids to correlate ACE2 and related host factors with SARS-CoV-2 tropism, propagation, virulence and immune activation compared to SARS-CoV, influenza and Middle East respiratory syndrome coronavirus (MERS-CoV). Coronavirus disease 2019 (COVID-19) autopsy material was used to validate ex vivo results.

RESULTS

We provide evidence that alveolar ACE2 expression must be considered scarce, thereby limiting SARS-CoV-2 propagation and virus-induced tissue damage in the human alveolus. Instead, ex vivo infected human lungs and COVID-19 autopsy samples showed that alveolar macrophages were frequently positive for SARS-CoV-2. Single-cell/-nucleus transcriptomics further revealed nonproductive virus uptake and a related inflammatory and anti-viral activation, especially in "inflammatory alveolar macrophages", comparable to those induced by SARS-CoV and MERS-CoV, but different from NL63 or influenza virus infection.

CONCLUSIONS

Collectively, our findings indicate that severe lung injury in COVID-19 probably results from a macrophage-triggered immune activation rather than direct viral damage of the alveolar compartment.

Mechanisms underlying acupuncture therapy in chronic kidney disease: A narrative overview of preclinical studies and clinical trials

Chronic kidney disease (CKD) is associated with high incidence, low awareness, and high disability rates among the population. Moreover, the disease significantly affects the physical and mental health of patients. Approximately 25% of patients with CKD develop end-stage renal disease (ESRD) within 20 years of diagnosis and have to rely on renal replacement therapy, which is associated with high mortality, heavy economic burden, and symptoms including fatigue, pain, insomnia, uremia pruritus, and restless leg syndrome. Currently, the means to delay the progress of CKD are insufficient; therefore, developing strategies for delaying CKD progression has important practical implications. In recent years, more and more people are accepting the traditional Chinese medical technique "acupuncture." Acupuncture has been shown to improve the uncomfortable symptoms of various diseases through stimulation (needling, medicinal moxibustion, infrared radiation, and acupressure) of acupoints. Its application has been known for thousands of years, and its safety and efficacy have been verified. As a convenient and inexpensive complementary therapy for CKD, acupuncture has recently been gaining interest among clinicians and scientists. Nevertheless, although clinical trials and meta-analysis findings have demonstrated the efficacy of acupuncture in reducing albuminuria, improving glomerular filtration rate, relieving symptoms, and improving the quality of life of patients with CKD, the underlying mechanisms involved are still not completely understood. Few studies explored the correlation between acupuncture and renal pathological diagnosis. The aim of this study was to conduct a literature review summarizing the currently known mechanisms by which acupuncture could delay the progress of CKD and improve symptoms in patients with ESRD. This review help provide a theoretical basis for further research regarding the influence of acupuncture on renal pathology in patients with CKD, as well as the differences between specific therapeutic mechanisms of acupuncture in different renal pathological diagnosis. The evidence in this review indicates that acupuncture may produce marked effects on blocking and reversing the critical risk factors of CKD progression (e.g., hyperglycemia, hypertension, hyperlipidemia, obesity, aging, and anemia) to improve the survival of patients with CKD via mechanisms including oxidative stress inhibition, reducing inflammatory effects, improving hemodynamics, maintaining podocyte structure, and increasing energy metabolism.

View of the Renin-Angiotensin System in Acute Kidney Injury Induced by Renal Ischemia-Reperfusion Injury

Renal ischemia-reperfusion injury (RIRI) is a sequence of complicated events that is defined as a reduction of the blood supply followed by reperfusion. RIRI is the leading cause of acute kidney injury (AKI). Among the diverse mediators that take part in RIRI-induced AKI, the renin-angiotensin system (RAS) plays an important role via conventional (angiotensinogen, renin, angiotensin-converting enzyme (ACE), angiotensin (Ang) II, and Ang II type 1 receptor (AT1R)) and nonconventional (ACE2, Ang 1-7, Ang 1-9, AT2 receptor (AT2R), and Mas receptor (MasR)) axes. RIRI alters the balance of both axes so that RAS can affect RIRI-induced AKI. In overall, the alteration of Ang II/AT1R and AKI by RIRI is important to consider. This review has looked for the effects and interactions of RAS activities during RIRI conditions.

Renal Denervation Influences Angiotensin II Types 1 and 2 Receptors

The sympathetic and renin-angiotensin systems (RAS) are two critical regulatory systems in the kidney which affect renal hemodynamics and function. These two systems interact with each other so that angiotensin II (Ang II) has the presynaptic effect on the norepinephrine secretion. Another aspect of this interaction is that the sympathetic nervous system affects the function and expression of local RAS receptors, mainly Ang II receptors. Therefore, in many pathological conditions associated with an increased renal sympathetic tone, these receptors' expression changes and renal denervation can normalize these changes and improve the diseases. It seems that the renal sympathectomy can alter Ang II receptors expression and the distribution of RAS receptors in the kidneys, which influence renal functions.

COVID-19 Pathology in the Lung, Kidney, Heart and Brain: The Different Roles of T-Cells, Macrophages, and Microthrombosis

Here, we aim to describe COVID-19 pathology across different tissues to clarify the disease's pathophysiology. Lungs, kidneys, hearts, and brains from nine COVID-19 autopsies were compared by using antibodies against SARS-CoV-2, macrophages-microglia, T-lymphocytes, B-lymphocytes, and activated platelets. Alzheimer's Disease pathology was also assessed. PCR techniques were used to verify the presence of viral RNA. COVID-19 cases had a short clinical course (0-32 days) and their mean age was 77.4 y/o. Hypoxic changes and inflammatory infiltrates were present across all tissues. The lymphocytic component in the lungs and kidneys was predominant over that of other tissues (p < 0.001), with a significantly greater presence of T-lymphocytes in the lungs (p = 0.020), which showed the greatest presence of viral antigens. The heart showed scant SARS-CoV-2 traces in the endothelium-endocardium, foci of activated macrophages, and rare lymphocytes. The brain showed scarce SARS-CoV-2 traces, prominent microglial activation, and rare lymphocytes. The pons exhibited the highest microglial activation (p = 0.017). Microthrombosis was significantly higher in COVID-19 lungs (p = 0.023) compared with controls. The most characteristic pathological features of COVID-19 were an abundance of T-lymphocytes and microthrombosis in the lung and relevant microglial hyperactivation in the brainstem. This study suggests that the long-term sequelae of COVID-19 derive from persistent inflammation, rather than persistent viral replication.

Angiotensin-converting enzyme 2 and transmembrane protease serine 2 in female and male patients with end-stage kidney disease

BACKGROUND

Individuals with chronic kidney disease are affected by acute respiratory syndrome coronavirus 2 (SARS-CoV-2) due to multiple comorbidities and altered immune system. The first step of the infection process is the binding of SARS-CoV-2 with angiotensin-converting enzyme 2 (ACE2) receptor, followed by its priming by transmembrane protease serine 2 (TMPRSS2). We hypothesized that circulating soluble ACE2 levels, as well as the expressions of ACE2 and TMPRSS2 in the microvasculature, are increased in patients with end-stage kidney disease (ESKD).

METHODS

A total of 210 participants were enrolled, representing 80 ESKD patients and 73 non-CKD controls for soluble ACE2, and 31 ESKD and 26 non-CKD controls for vasculature and fat tissue bioassays. We have assessed ACE2 expression in blood using ELISA and in tissue using immunofluorescence.

RESULTS

Soluble ACE2 levels were higher in ESKD patients compared to controls; however, there is no sex difference observed. In ESKD and controls, soluble ACE2 positively correlated with Interleukin 6 (IL-6) and C-reactive protein (CRP), respectively. Similarly, ACE2 tissue expression in the vasculature was higher in ESKD patients; moreover, this higher ACE2 expression was observed only in male ESKD patients. In addition, TMPRSS2 expression was observed in vessels from males and females but showed no sex difference. The expression of ACE2 receptor was higher in ESKD patients on ACE-inhibitor/angiotensin blocker treatment.

CONCLUSION

ESKD is associated with increased ACE2 levels in the circulation and pronounced in male vasculature; however, further studies are warranted to assess possible sex differences on specific treatment regime(s) for different comorbidities present in ESKD.

Targeting ACE2 as a potential prophylactic strategy against COVID-19-induced exacerbation of chronic kidney disease

Patients with chronic kidney disease (CKD) are at higher risk for severe coronavirus disease 2019 (COVID-19). Such patients are more likely to develop “COVID-19-induced acute kidney injury (AKI)”, which exacerbates the pre-existing CKD and increases the mortality rate of the patients. COVID-19-induced AKI is pathologically characterized by acute tubular necrosis and the interstitial infiltration of proinflammatory leukocytes. In our rat model with advanced CKD, immunohistochemistry for angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2) demonstrated their strong expression in the cytoplasm of damaged proximal tubular cells and the infiltrating leukocytes within the cortical interstitium, which overlapped with the lesions of COVID-19-induced AKI. Since ACE2 and TMPRSS2 are enzymes that facilitate the viral entry into the cells and trigger the onset of cytokine storm, the renal distribution of these proteins in advanced CKD was thought to be responsible for the development of COVID-19-induced AKI. Concerning such mechanisms, the pharmacological blockade of ACE2 or the use of soluble forms of the ACE2 protein may halt the entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) into host cells. This would protect against the COVID-19-induced exacerbation of pre-existing CKD by preventing the development of AKI.

Potential Similarities in Sex Difference in Key Genes and Their Expression, Network, EQTL and Pathways between COVID-19 and Chronic Kidney Disease Based on Mouse Model

COVID-19 and chronic kidney disease (CKD) share similarity in sex bias and key genes in the disease pathway of sex difference. We investigated the sex difference of molecular pathways of four key players of these two diseases using an existing large set of whole genome expression profiles from the kidneys of female and male mouse models. Our data show that there is little to no correlation at the whole genome expression level between female and male mice among these four genes. There are considerable sex differences among genes in upstream regulation, Ace2 complex interaction, and downstream pathways. Snap25 and Plcb4 may play important roles in the regulation of the expression level of Adam17, Tmprss2, and Cd146 in females. In males, Adh4 is a candidate gene for the regulation of Adam17, while Asl, Auts2, and Rabger1 are candidates for Tmprss2. Within the Ace2 complex, Cd146 directly influences the expression level of Adam17 and Ace2 in the female, while in the male Adam potentially has a stronger influence on Ace2 than that of Tmprss2. Among the top 100 most related genes, only one or two genes from four key genes and 11 from the control B-Actin were found to be the same between sexes. Among the top 10 sets of genes in the downstream pathway of Ace2, only two sets are the same between the sexes. We concluded that these known key genes and novel genes in CKD may play significant roles in the sex difference in the CKD and COVID-19 disease pathways.

The Race for ACE: Targeting Angiotensin-Converting Enzymes (ACE) in SARS-CoV-2 Infection

The SARS-CoV-2 virus is spreading around the world, and its clinical manifestation COVID-19 is challenging medical, economic, and social systems. With more and more scientific and social media reports on the COVID-19 pandemic appearing, differences in geographical presentations and clinical management occur. Since ACE2 (angiotensin-converting enzyme 2) is the gatekeeper receptor for the SARS-CoV-2 virus in the upper bronchial system, we here focus on the central role of the renin-angiotensin aldosterone system (RAAS) in the SARS-CoV-2 virus infection, the role of pharmacological RAAS inhibitors, and specific genetic aspects, i.e., single nucleotide polymorphisms (SNP) for the clinical outcome of COVID-19. We aimed to bring together clinical, epidemiological, molecular, and pathophysiological and pharmacological data/observations on cardiovascular aspects in the actual SARS-CoV-2 virus pandemic. In detail, we will report controversies about the Yin-Yan between ACE2 and ACE1 and potential implications for the treatment of hypertension, coronary artery disease, and heart failure. Here, we summarize the encouraging and dynamic global effort of multiple biomedical disciplines resulted in astonishing fight against COVID-19 targeting the renin-angiotensin-aldosterone system, yet the race for ACE just begun.

sFlt-1 Is an Independent Predictor of Adverse Maternal Outcomes in Women With SARS-CoV-2 Infection and Hypertensive Disorders of Pregnancy

Background

Preeclampsia (PE) and COVID-19 share a common vascular–endothelial physiopathological pathway that may aggravate or worsen women's outcomes when both coexist. This study aims to evaluate the association of sFlt-1 levels and adverse maternal outcomes among positive SARS-CoV-2 pregnant women with and without hypertensive disorders of pregnancy (HDP).

Methods

We performed a multicenter retrospective cohort study of pregnant women with confirmed SARS-CoV-2 infection that required hospital admission. The exposed cohort comprised women with a diagnosis of an HDP. The primary outcome was a composite definition of adverse maternal outcome. The association between predictors and the main and secondary outcomes was assessed using an elastic-net regression which comprised a Lasso and Ridge regression method for automatic variable selection and penalization of non-statistically significant coefficients using a 10-fold cross-validation where the best model if automatically chosen by the lowest Akaike information criterion (AIC) and Bayesian information criteria (BIC).

Results

Among 148 pregnant women with COVID-19, the best predictive model comprised sFlt-1 MoMs [odds ratio (OR): 5.13; 95% CI: 2.19–12.05], and HDP (OR: 32.76; 95% CI: 5.24–205). sFlt-1 MoMs were independently associated with an increased probability of an adverse maternal outcome despite adjusting for HDP.

Conclusions

Our study shows that sFlt-1 is an independent predictor of adverse outcomes in women with SARS-CoV-2 despite hypertension status.

COVID-19 and Acute Kidney Injury: A Systematic Review

Introduction

Acute kidney injury (AKI) has been associated with an increased mortality rate among hospitalized patients with Coronavirus disease 2019 (COVID-19). The current review aimed to evaluate the symptoms, complications, and treatments performed to manage AKI in patients with COVID-19.

Methods

We searched PubMed/Medline, Web of Science, and Embase for the relevant scientific literature published up to February 1, 2022. The following keywords were used: “COVID-19”, “SARS-CoV-2”, and “Acute kidney injury”.

Results

Forty-four studies with a total number of 114 COVID-19 patients with AKI (Mean age: 53.6 years) were included in our systematic review. The most common comorbidities in patients with COVID-19 suffering from AKI were the history of diabetes, hypertension, and hyperlipidemia. Twelve out of the 44 included studies reported a history of chronic kidney disease (CKD) in this group of patients. Focal segmental glomerulosclerosis (FSGS) and acute tubular necrosis (ATN) were the most common pathological evidence. The average length of hospital stay was 19 days, and the average duration of need for mechanical ventilation was 3 days.

Conclusions

The current systematic review shows that AKI frequently complicates the course of COVID-19 hospitalizations and is associated with increased severity of illness, prolonged duration of hospitalization, and poor prognosis. Given the extent of the adverse impact of AKI, early detection of comorbidities and renal complications is essential to improve the outcomes of COVID-19 patients.

SARS-CoV-2 Employ BSG/CD147 and ACE2 Receptors to Directly Infect Human Induced Pluripotent Stem Cell-Derived Kidney Podocytes

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes the Coronavirus disease 2019 (COVID-19), which has resulted in over 5.9 million deaths worldwide. While cells in the respiratory system are the initial target of SARS-CoV-2, there is mounting evidence that COVID-19 is a multi-organ disease. Still, the direct affinity of SARS-CoV-2 for cells in other organs such as the kidneys, which are often targeted in severe COVID-19, remains poorly understood. We employed a human induced pluripotent stem (iPS) cell-derived model to investigate the affinity of SARS-CoV-2 for kidney glomerular podocytes, and examined the expression of host factors for binding and processing of the virus. We studied cellular uptake of the live SARS-CoV-2 virus as well as a pseudotyped virus. Infection of podocytes with live SARS-CoV-2 or spike-pseudotyped lentiviral particles revealed cellular uptake even at low multiplicity of infection (MOI) of 0.01. We found that direct infection of human iPS cell-derived podocytes by SARS-CoV-2 virus can cause cell death and podocyte foot process retraction, a hallmark of podocytopathies and progressive glomerular diseases including collapsing glomerulopathy observed in patients with severe COVID-19 disease. We identified BSG/CD147 and ACE2 receptors as key mediators of spike binding activity in human iPS cell-derived podocytes. These results show that SARS-CoV-2 can infect kidney glomerular podocytes in vitro via multiple binding interactions and partners, which may underlie the high affinity of SARS-CoV-2 for kidney tissues. This stem cell-derived model is potentially useful for kidney-specific antiviral drug screening and mechanistic studies of COVID-19 organotropism.

Functional ACE2 deficiency leading to angiotensin imbalance in the pathophysiology of COVID-19

SARS-CoV-2, the virus responsible for COVID-19, uses angiotensin converting enzyme 2 (ACE2) as its primary cell-surface receptor. ACE2 is a key enzyme in the counter-regulatory pathway of the broader renin-angiotensin system (RAS) that has been implicated in a broad array of human pathology. The RAS is composed of two competing pathways that work in opposition to each other: the "conventional" arm involving angiotensin converting enzyme (ACE) generating angiotensin-2 and the more recently identified ACE2 pathway that generates angiotensin (1-7). Following the original SARS pandemic, additional studies suggested that coronaviral binding to ACE2 resulted in downregulation of the membrane-bound enzyme. Given the similarities between the two viruses, many have posited a similar process with SARS-CoV-2. Proponents of this ACE2 deficiency model argue that downregulation of ACE2 limits its enzymatic function, thereby skewing the delicate balance between the two competing arms of the RAS. In this review we critically examine this model. The available data remain incomplete but are consistent with the possibility that the broad multisystem dysfunction of COVID-19 is due in large part to functional ACE2 deficiency leading to angiotensin imbalance with consequent immune dysregulation and endothelial cell dysfunction.

Research status and progress of metabolic associated fatty liver disease

Metabolic associated fatty liver disease (MAFLD) is a more appropriate general predicate to describe non-alcoholic fatty liver disease. The new definition lists metabolic dysfunction as an important cause of liver disease, demonstrates the high heterogeneity of this condition, and speeds up the transformation path to new treatment. The incidence of extrahepatic complications and related diseases of MAFLD far exceed that of the liver disease itself, which seriously threatens human health. In view of the current insufficient understanding of its severity, and the imperfect understanding of the disease scope, pathogenesis, and diagnosis of extrahepatic complications, especially the lack of effective drug treatment, this paper introduces and reviews the research status and progress of extrahepatic complications of MAFLD.