Alteration and association between serum ACE2/ angiotensin(1-7)/Mas axis and oxidative stress in chronic kidney disease: A pilot study

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.

Impact of the ACE2 activator xanthenone on tacrolimus nephrotoxicity: Modulation of uric acid/ERK/p38 MAPK and Nrf2/SOD3/GCLC signaling pathways

AIMS

The calcineurin inhibitor tacrolimus is an effective and widely used immunosuppressant after organ transplantation to reduce graft rejection. However, its nephrotoxic effect could compel the patients to treatment discontinuation. The beneficial effects of angiotensin-converting enzyme 2 (ACE2) on the kidney and other organs have been investigated in several studies, but its role in tacrolimus nephrotoxicity still needs to be elucidated. Our study was designed to investigate effects of the ACE2 activator xanthenone on tacrolimus-induced renal injury.

MATERIALS AND METHODS

Male Wistar rats were administered xanthenone (2 mg/kg) concurrently with tacrolimus (1 mg/kg) for 3 weeks, then blood and kidney tissue samples were collected for biochemical and molecular investigations.

KEY FINDINGS

Co-administration of xanthenone significantly improved renal functions in tacrolimus-treated rats, where serum creatinine, urea, and uric acid levels were close to those of the normal control. Besides, xanthenone reduced renal angiotensin (ANG) II content, while elevated ANG (1-7). Relative protein expressions of p-ERK/ERK and p-p38 MAPK/p38 MAPK inflammatory signals were downregulated upon xanthenone administration with tacrolimus. In addition, xanthenone reinforced antioxidant defense against tacrolimus by enhancing protein expression of the transcription factor Nrf2 with subsequently increased mRNA expressions of the antioxidants SOD3 and GCLC.

SIGNIFICANCE

These protective effects of xanthenone could be attributed to ANG II degradation to ANG (1-7) by ACE2 activation resulting in regulated inflammatory and oxidative responses in the kidney. Therefore, administration of xanthenone along with tacrolimus could be a promising therapeutic strategy to reduce the adverse effects and increase the tolerability to tacrolimus immunosuppressive therapy.

Renal biomarkers of acute kidney injury in response to increasing intermittent hypoxia episodes in the neonatal rat

BACKGROUND

We tested the hypotheses that: 1) early exposure to increasing episodes of clinically relevant intermittent hypoxia (IH) is detrimental to the developing kidneys; and 2) there is a critical number of daily IH episodes which will result in irreparable renal damage that may involve angiotensin (Ang) II and endothelin (ET)-1.

METHODS

At birth (P0), neonatal rat pups were exposed to brief IH episodes from the first day of life (P0) to P7 or from P0-P14. Pups were either euthanized immediately or placed in room air (RA) until P21. RA littermates served as controls. Kidneys were harvested at P7, P14, and P21 for histopathology; angiotensin converting enzyme (ACE), ACE-2, ET-1, big ET-1, and malondialdehyde (MDA) levels; immunoreactivity of ACE, ACE-2, ET-1, ET-2, ET receptors (ETAR, ETBR), and hypoxia inducible factor (HIF)1α; and apoptosis (TUNEL stain).

RESULTS

Histopathology showed increased renal damage with 8-12 IH episodes/day, and was associated with Ang II, ACE, HIF1α, and apoptosis. ACE-2 was not expressed at P7, and minimally increased at P14. However, a robust ACE-2 response was seen during recovery with maximum levels noted in the groups recovering from 8 IH episodes/day. ET-1, big ET-1, ETAR, ETBR, and MDA increased with increasing levels of neonatal IH.

CONCLUSIONS

Chronic neonatal IH causes severe damage to the developing kidney with associated elevations in vasoconstrictors, suggesting hypertension, particularly with 8 neonatal IH episodes. ACE-2 is not activated in early postnatal life, and this may contribute to IH-induced vasoconstriction. Therapeutic targeting of ACE and ET-1 may help decrease the risk for kidney injury in the developing neonate to prevent and/or treat neonatal acute kidney injury and/or chronic kidney disease.

Outcomes of coronavirus 2019 infection in patients with chronic kidney disease: a systematic review and meta-analysis

BACKGROUND

Information on coronavirus disease 2019 (COVID-19) infection in patients with chronic kidney disease (CKD) remains limited. To understand the influence of COVID-19 infection in patients with pre-existing CKD, we conducted a systematic review and meta-analysis to evaluate and compare the risks of all-cause mortality, hospitalization, and critical progression between patients with and without CKD.

METHODS

We selected randomized controlled trials (RCTs), prospective or retrospective observational, case-control, cross-sectional, and case-series studies analyzing outcomes of COVID-19 infection in patients with pre-existing CKD from the PubMed, Embase, and Cochrane Central Register of Controlled Trials databases published on the Internet before 16 July 2020.

RESULTS

A total of 27 studies comprising 77,856 patients with COVID-19 infection was identified; 3922 patients with pre-existing CKD were assigned CKD group, and 73,934 patients were assigned to the non-CKD group. The pooled analysis showed that patients with CKD had a significantly higher risk of all-cause mortality and hospitalization than those without CKD [odds ratio (OR) 2.25, 95% confidence interval (CI) 1.91-2.66, p < 0.001; OR 4.29, 95% CI 2.93-6.28, p < 0.001; respectively]. Patients with CKD had a higher risk of critically ill conditions than those without CKD in the pooled analysis of studies with multivariable adjustment (adjusted OR 2.12, 95% CI 0.95-4.77, p = 0.07) and in the analysis of all included studies (OR 1.27, 95% CI 0.71-2.26, p = 0.41), but both analyses did not attain statistical significance.

CONCLUSION

COVID-19 infected patients with CKD had significantly increased risks of all-cause mortality and hospitalization compared with those without CKD.

COVID-19

In 2019, a novel coronavirus infection was detected in humans. As coronavirus disease 2019 (COVID-19) spread around the world, often confusing and contradictory information about the disease proliferated rapidly. This article reviews what is currently known about COVID-19, including transmission, epidemiology, immunologic responses, clinical manifestations, and disease management.

In 2019, a novel coronavirus infection was detected in humans. As coronavirus disease 2019 (COVID-19) spread around the world, often confusing and contradictory information about the disease proliferated rapidly. This article reviews what is currently known about COVID-19, including transmission, epidemiology, immunologic responses, clinical manifestations, and disease management.