Long-term renal outcomes of patients with COVID-19: a meta-analysis of observational studies.

BACKGROUND: Kidney involvement is common in hospitalized coronavirus disease 2019 (COVID-19) patients during the acute phase, little is known about the long-term impact of COVID-19 on the kidney. METHODS: This is a systematic review and meta-analysis on long-term renal outcomes among COVID-19 patients. We carried out a systematic literature search in PUBMED, EMBASE, SCOPUS, and Cochrane COVID-19 study register and performed the random-effects meta-analysis of rates. The search was last updated on November 23, 2022. RESULTS: The study included 12 moderate to high-quality cohort studies involving 6976 patients with COVID-19-associated acute kidney injury and 5223 COVID-19 patients without acute kidney injury. The summarized long-term renal non-recovery rate, dialysis-dependent rate, and complete recovery rate among patients with COVID-19-associated AKI was 22% (12-33%), 6% (2-12%), and 63% (44-81%) during a follow-up of 90-326.5 days. Heterogeneity could be explained by differences in the prevalence of chronic kidney disease and proportion of acute kidney injury requiring renal replacement therapy using meta-regression; patients with more comorbidities or higher renal replacement therapy rate had higher non-recovery rates. The summarized long-term kidney function decrease rate among patients without acute kidney injury was 22% (3-51%) in 90-199 days, with heterogeneity partially explained by severity of infection. CONCLUSION: Patients with more comorbidities tend to have a higher renal non recovery rate after COVID-19-associated acute kidney injury; for COVID-19 patients without acute kidney injury, decrease in kidney function may occur during long-term follow-up. Regular evaluation of kidney function during the post-COVID-19 follow-up among high-risk patients may be necessary.

Clinicopathological Features of Kidney Injury Related to Immune Checkpoint Inhibitors: A Systematic Review.

(1) Background: Despite increasing recognition of immune checkpoint inhibitors (ICIs) and kidney immune-related adverse events (IRAEs), no large-sample studies have assessed the pathological characteristics and outcomes of biopsy-proven kidney IRAEs. (2) Methods: We comprehensively searched PubMed, Embase, Web of Science, and Cochrane for case reports, case series, and cohort studies for patients with biopsy-proven kidney IRAEs. All data were used to describe pathological characteristics and outcomes, and individual-level data from case reports and case series were pooled to analyze risk factors associated with different pathologies and prognoses. (3) Results: In total, 384 patients from 127 studies were enrolled. Most patients were treated with PD-1/PD-L1 inhibitors (76%), and 95% presented with acute kidney disease (AKD). Acute tubulointerstitial nephritis/acute interstitial nephritis (ATIN/AIN) was the most common pathologic type (72%). Most patients (89%) received steroid therapy, and 14% (42/292) required RRT. Among AKD patients, 17% (48/287) had no kidney recovery. Analyses of pooled individual-level data from 221 patients revealed that male sex, older age, and proton pump inhibitor (PPI) exposure were associated with ICI-associated ATIN/AIN. Patients with glomerular injury had an increased risk of tumor progression (OR 2.975; 95% CI, 1.176, 7.527; p = 0.021), and ATIN/AIN posed a decreased risk of death (OR 0.164; 95% CI, 0.057, 0.473; p = 0.001). (4) Conclusions: We provide the first systematic review of biopsy-proven ICI-kidney IRAEs of interest to clinicians. Oncologists and nephrologists should consider obtaining a kidney biopsy when clinically indicated.

Human Amnion Epithelial Cells and Their Derived Exosomes Alleviate Sepsis-Associated Acute Kidney Injury via Mitigating Endothelial Dysfunction.

Background: Sepsis is characterized by organ dysfunction resulting from a patient's dysregulated response to infection. Sepsis-associated acute kidney injury (S-AKI) is the most frequent complication contributing to the morbidity and mortality of sepsis. The prevention and treatment of S-AKI remains a significant challenge worldwide. In the recent years, human amnion epithelial cells (hAECs) have drawn much attention in regenerative medicine, yet the therapeutic efficiency of hAECs in S-AKI has not been evaluated. Methods: Septic mice were induced by cecal ligation and puncture (CLP) operation. hAECs and their derived exosomes (EXOs) were injected into the mice via tail vein right after CLP surgery. The 7-day survival rate was observed. Serum creatinine level was measured and H&E staining of tissue sections were performed 16 h after CLP. Transmission electron microscopy was used to examine the renal endothelial integrity in CLP mice. Human umbilical vein endothelial cells (HUVECs) were treated with lipopolysaccharide (LPS) and EXOs. Zonula occludens-1 (ZO-1) localization was observed by immunofluorescence staining. Expression of phosphor-p65 (p-p65), p65, vascular cell adhesion molecule-1 (VCAM-1), and ZO-1 in the kidney were determined by Western blot. Results: hAECs decreased the mortality of CLP mice, ameliorated septic injury in the kidney, and improved kidney function. More precisely, hAECs suppressed systemic inflammation and maintained the renal endothelial integrity in septic animals. EXOs from hAECs exhibited similar renal protective effects as their parental cells. EXOs maintained endothelial cell adhesion junction in vitro and inhibited endothelial cell hyperactivation in vivo. Mechanistically, EXOs suppressed proinflammatory nuclear factor kappa B (NF-κB) pathway activation in LPS-treated HUVECs and in CLP mice kidneys. Conclusion: Our results indicate that hAECs and their derived EXOs may ameliorate S-AKI via the prevention of endothelial dysfunction in the early stage of sepsis in mice. Stem cell or exosome-based therapy targeting endothelial disorders may be a promising alternative for treatment of S-AKI.

Joint Predictive Value of cTnI and NT-proBNP on Mortality in Patients with Coronavirus Disease 2019: A Retrospective Research in Wuhan, China.

BACKGROUND AND OBJECTIVES: The pandemic of coronavirus disease 2019 (COVID-19) remains to be the biggest public threat all over the world. Because of the rapid deterioration in some patients, markers that could predict poor clinical outcomes are urgently required. This study was to evaluate the predictive values of cardiac injury parameters, including cardiac troponin I (cTnI) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels, on mortality in COVID-19 patients. METHODS: COVID-19 patients in Zhongfaxincheng branch of Tongji Hospital (Wuhan, China) from February 8-28, 2020, were enrolled in this study. We followed up the patients for 30 days after admission. RESULTS: A total of 134 patients were included in the study. Multivariate Cox regression showed that 1) patients with elevated cTnI levels had a higher risk of death (hazard ratio [HR] 7.33, 95% confidence interval [CI] 2.56-21.00) than patients with normal cTnI levels; 2) patients with elevated NT-proBNP levels had a higher risk of death (HR 27.88, 95% CI 3.55-218.78) than patients with normal NT-proBNP levels; 3) patients with both elevated cTnI and NT-proBNP levels had a significantly higher risk of death (HR 53.87, 95% CI 6.31-459.91, P < 0.001) compared to patients without elevated cTnI or NT-proBNP levels; 4) the progressions of cTnI and NT-proBNP levels were also correlated with death (HR 12.70, 95% CI 3.94-40.88, P < 0.001 and HR 51.09, 95% CI 5.82-448.26, P < 0.001). CONCLUSIONS: In COVID-19 patients, cTnI and NT-proBNP levels could be monitored to identify patients at a high risk of death in their later course of disease.

Effect of clinical decision support systems on clinical outcome for acute kidney injury: a systematic review and meta-analysis.

BACKGROUND: Clinical decision support systems including both electronic alerts and care bundles have been developed for hospitalized patients with acute kidney injury. METHODS: Electronic databases were searched for randomized, before-after and cohort studies that implemented a clinical decision support system for hospitalized patients with acute kidney injury between 1990 and 2019. The studies must describe their impact on care processes, patient-related outcomes, or hospital length of stay. The clinical decision support system included both electronic alerts and care bundles. RESULTS: We identified seven studies involving 32,846 participants. Clinical decision support system implementation significantly reduced mortality (OR 0.86; 95 % CI, 0.75-0.99; p = 0.040, I2 = 65.3 %; n = 5 studies; N = 30,791 participants) and increased the proportion of acute kidney injury recognition (OR 3.12; 95 % CI, 2.37-4.10; p < 0.001, I2 = 77.1 %; n = 2 studies; N = 25,121 participants), and investigations (OR 3.07; 95 % CI, 2.91-3.24; p < 0.001, I2 = 0.0 %; n = 2 studies; N = 25,121 participants). CONCLUSIONS: Nonrandomized controlled trials of clinical decision support systems for acute kidney injury have yielded evidence of improved patient-centered outcomes and care processes. This review is limited by the low number of randomized trials and the relatively short follow-up period.

A cross-sectional study of chemotherapy-related AKI.

PURPOSE: This study aims to detail the characteristics of chemotherapy-related acute kidney injury (CR-AKI) and investigate its effect on patient outcomes. METHODS: This is a multicenter cross-sectional study of cancer patients with CR-AKI screened from hospital-acquired adult AKI patients based on a nationwide AKI survey in China. RESULTS: Of the 3468 patients with hospital-acquired AKI, 258 cases of CR-AKI were identified. Of the patients, 20.1% (52/258) were ≥ 70 years old. Among the 258 CR-AKI cases, 61 (23.6%) reached AKI stage 3, and 75 (29.1%) reached AKI stage 2. The remaining 122 (47.3%) remained at AKI stage 1. A total of 413 chemotherapeutic agents were related to AKI, of which platinum compounds (24.5%, 101/413) were the most common. In-hospital mortality was 14.7% (38/258), and the rate of AKI non-recovery was 48.3% (100/207). AKI stage 3 (OR 2.930, 95% CI 1.156-7.427) and age ≥ 70 years (OR 3.138, 95% CI 1.309-7.519) were independent risk factors for in-hospital death. Compared to stage 2 or 3 AKI cases, a higher proportion of patients with stage 1 AKI did not recover their renal function (57.1% vs. 41.4% vs. 36.4%, P = 0.032). More AKI episodes were not recognized in patients with stage 1 AKI compared with the other two groups (82.8% vs. 60.0% vs. 36.1%, P < 0.001). CONCLUSIONS: CR-AKI accounted for a noteworthy proportion of hospital-acquired AKI, and severe CR-AKI increased in-hospital mortality. Mild CR-AKI was more likely to be overlooked, and sustained kidney injury was common in this situation. Recognizing CR-AKI at an early stage and personalizing treatment should be emphasized in those undergoing chemotherapy.

Association Between Average Plasma Potassium Levels and 30-day Mortality During Hospitalization in Patients with COVID-19 in Wuhan, China.

Background: Coronavirus disease 2019 (COVID-19) has resulted in more than 610,000 deaths worldwide since December 2019. Given the rapid deterioration of patients' condition before death, markers with efficient prognostic values are urgently required. During the treatment process, notable changes in plasma potassium levels have been observed among severely ill patients. We aimed to evaluate the association between average plasma potassium (Ka +) levels during hospitalization and 30-day mortality in patients with COVID-19. Methods: Consecutive patients with COVID-19 hospitalized in the Zhongfaxincheng branch of Tongji Hospital in Wuhan, China from February 8 to 28, 2020 were enrolled in this study. We followed patients up to 30 days after admission. Results: A total of 136 patients were included in the study. The average age was 62.1±14.6 years and 51.5% of patients were male. The median baseline potassium level was 4.3 (3.9-4.6) mmol/L and Ka + level during hospitalization was 4.4 (4.2-4.7) mmol/L; the median number of times that we measured potassium was 4 (3-5). The 30-day mortality was 19.1%. A J-shaped association was observed between Ka + and 30-day mortality. Multivariate Cox regression showed that compared with the reference group (Ka + 4.0 to <4.5 mmol/L), 30-day mortality was 1.99 (95% confidence interval [CI]=0.54-7.35, P=0.300), 1.14 (95% CI=0.39-3.32, P=0.810), and 4.14 (95% CI=1.29-13.29, P=0.017) times higher in patients with COVID-19 who had Ka + <4.0, 4.5 to <5.0, and ≥5.0 mmol/L, respectively. Conclusion: Patients with COVID-19 who had a Ka + level ≥5.0 mmol/L had a significantly increased 30-day mortality compared with those who had a Ka + level 4.0 to <4.5 mmol/L. Plasma potassium levels should be monitored routinely and maintained within appropriate ranges in patients with COVID-19.

Elevated resting heart rates are a risk factor for mortality among patients with coronavirus disease 2019 in Wuhan, China.

BACKGROUND: We evaluated the association between higher resting heart rates (RHRs) and adverse events in COVID-19 patients. METHODS: One hundred and thirty-six patients with laboratory-confirmed COVID-19 were admitted. Outcomes of patients with different RHRs were compared. RESULTS: Twenty-nine patients had RHRs of <80 bpm (beat per min), 85 had 80-99 bpm and 22 had ≥100 bpm as tachycardia. Those with higher RHRs had lower pulse oxygen saturation (SpO2) and higher temperatures, and there was a higher proportion of men upon admission (all P < 0.05). Patients with higher RHRs showed higher white blood cell counts and D-dimer, cardiac troponin I (TnI), N-terminal pro-B-type natriuretic peptide and hypersensitive C-reactive protein levels, but lower albumin levels (all P < 0.05) after admission. During follow-up, 26 patients died (mortality rate, 19.1%). The mortality rate was significantly higher among patients with tachycardia than among the moderate and low RHR groups (all P < 0.001). Kaplan-Meier survival curves showed that the risks of death and ventilation use increased for patients with tachycardia (P < 0.001). Elevated RHR as a continuous variable and a mean RHR as tachycardia were independent risk factors for mortality and ventilator use (all P < 0.05) in the multivariable adjusted Cox proportional hazards regression model. CONCLUSIONS: Elevated average RHRs during the first 3 days of hospitalisation were associated with adverse outcomes in COVID-19 patients. Average RHRs as tachycardia can independently predict all-cause mortality.

Acute Kidney Injury Relevant to Tubulointerstitial Nephritis with Late-Onset Uveitis Superimposed by Thrombotic Microangiopathy: A Case Report and Review of the Literature.

BACKGROUND: The syndrome of tubulointerstitial nephritis and uveitis (TINU) is an uncommon and multisystemic autoimmune disorder. This review reports a rare case of TINU being superimposed on thrombotic microangiopathy (TMA) and, by comparing with the available literature, also summarizes the clinical features, associated conditions, treatment, and outcome of patients with TINU. SUMMARY: Herein, we report the case of a 37-year-old male patient with acute kidney injury (AKI) clinicopathologically identified as malignant hypertension-induced TMA superimposed by acute tubulointerstitial nephritis, which was suspected to be related to drug hypersensitivity. After treatment with oral prednisone combined with a renin-angiotensin system inhibitor, the patient achieved partial renal recovery and was withdrawn from hemodialysis. Recurrent AKI concomitant with new-onset asymptomatic uveitis was detected during routine clinical follow-up after cessation of prednisone. TINU was then diagnosed, and prednisone followed by cyclophosphamide was prescribed. The patient achieved better renal recovery than in the first round of treatment and maintained stable renal function afterward. By reviewing the literature, 36 cases were reported as TINU superimposed on other conditions, including thyroiditis, osteoarthropathy, and sarcoid-like noncaseating granulomas. KEY MESSAGES: TINU could be complicated by many other conditions, among which TMA is very rare. When presented as AKI, kidney biopsy is important for differential diagnosis. The case also shows that recurrent AKI with concomitant uveitis after prednisone withdrawal strongly suggested the need for long-term follow-up and elongated prednisone therapy for TINU syndrome.

Early predictive factors of progression from severe type to critical ill type in patients with Coronavirus Disease 2019: A retrospective cohort study.

BACKGROUND: The current worldwide pandemic of Coronavirus Disease 2019 (COVID-19) has posed a serious threat to global public health, and the mortality rate of critical ill patients remains high. The purpose of this study was to identify factors that early predict the progression of COVID-19 from severe to critical illness. METHODS: This retrospective cohort study included adult patients with severe or critical ill COVID-19 who were consecutively admitted to the Zhongfaxincheng campus of Tongji Hospital (Wuhan, China) from February 8 to 18, 2020. Baseline variables, data at hospital admission and during hospital stay, as well as clinical outcomes were collected from electronic medical records system. The primary endpoint was the development of critical illness. A multivariable logistic regression model was used to identify independent factors that were associated with the progression from severe to critical illness. RESULTS: A total of 138 patients were included in the analysis; of them 119 were diagnosed as severe cases and 16 as critical ill cases at hospital admission. During hospital stay, 19 more severe cases progressed to critical illness. For all enrolled patients, longer duration from diagnosis to admission (odds ratio [OR] 1.108, 95% CI 1.022-1.202; P = 0.013), pulse oxygen saturation at admission <93% (OR 5.775, 95% CI 1.257-26.535; P = 0.024), higher neutrophil count (OR 1.495, 95% CI 1.177-1.899; P = 0.001) and higher creatine kinase-MB level at admission (OR 2.449, 95% CI 1.089-5.511; P = 0.030) were associated with a higher risk, whereas higher lymphocyte count at admission (OR 0.149, 95% CI 0.026-0.852; P = 0.032) was associated with a lower risk of critical illness development. For the subgroup of severe cases at hospital admission, the above factors except creatine kinase-MB level were also found to have similar correlation with critical illness development. CONCLUSIONS: Higher neutrophil count and lower lymphocyte count at admission were early independent predictors of progression to critical illness in severe COVID-19 patients.

Acute Kidney Injury in COVID-19: The Chinese Experience.

Coronavirus disease 2019 (COVID-19) is spreading rapidly worldwide. Here, we review recently published studies on COVID-19-associated acute kidney injury (AKI) in China. The pooled incidence of AKI in all reported COVID-19 patients was 6.5%, with a much higher rate in patients from the intensive care unit (32.5%). AKI is associated with the severity of COVID-19 and mortality rates, which is similar to other kidney abnormalities including proteinuria and hematuria. The renal tubule is the main site of injury in COVID-19 patients, and the etiology of renal impairment in COVID-19 patients likely is diverse and multifactorial. Apart from direct viral attack via angiotensin-converting enzyme 2 and transmembrane serine proteases 2, hypoxia and hypercoagulability also may contribute to the occurrence of renal injury. To date, there is only randomized controlled trial evidence to support the use of dexamethasone in patients requiring oxygen therapy and remdesivir for shortening the time to recovery, with no specific treatment for COVID-19-associated AKI. Studies researching kidney pathologies or reporting renal outcome and prognosis are in urgent need. Further studies are urgently warranted to identify risk factors, to predict prognosis and renal outcome, to explore the exact mechanisms of renal injury, and to suggest targeted interventions.

Elevation of erythrocyte sedimentation rate and C-reactive protein levels reflects renal interstitial inflammation in drug-induced acute tubulointerstitial nephritis.

BACKGROUND: A renal biopsy is needed to define active inflammatory infiltration and guide therapeutic management in drug-induced acute tubulointerstitial nephritis (D-ATIN). However, factors such as various contraindications, refusal of informed consent and limited technical support may stop the biopsy process. It is thus of great importance to explore approaches that could deduce probable pathologic changes. METHODS: A total of 81 biopsy-proven D-ATIN patients were enrolled from a prospective cohort of ATIN patients at Peking University First Hospital. The systemic inflammation score (SIS) was developed based on the CRP and ESR levels at biopsy, and patients were divided into high-SIS, median-SIS, and low-SIS groups. The demographic data, clinicopathologic features, and renal outcomes were compared. RESULTS: The SIS was positively correlated with inflammatory cell infiltration and was inversely correlated with interstitial fibrosis. The number of interstitial inflammatory cells increased significantly with increasing SISs. The proportions of neutrophils and plasma cells were the highest in the high-SIS group compared with the other two groups. Prednisone (30-40 mg/day) was prescribed in all patients. The high-SIS group tended to have more favorable renal restoration than the other two groups. By 12 months postbiopsy, a decreased eGFR (< 60 mL/min/1.73 m2) was observed in 66.7% of medium-SIS patients, 32.4% of high-SIS patients, and 30.4% of low-SIS patients. CONCLUSION: The SIS was positively correlated with active tubulointerstitial inflammation and therefore could help to aid therapeutic decisions in D-ATIN.

Prevalence of Kidney Injury and Associations with Critical Illness and Death in Patients with COVID-19.

BACKGROUND AND OBJECTIVES: Coronavirus disease 2019 is spreading rapidly across the world. This study aimed to assess the characteristics of kidney injury and its association with disease progression and death of patients with coronavirus disease 2019. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This is a retrospective study. Two representative cohorts were included. Cohort 1 involved severe and critical patients with coronavirus disease 2019 from Wuhan, China. Cohort 2 was all patients with coronavirus disease 2019 in Shenzhen city (Guangdong province, China). Any kidney injury was defined as the presence of any of the following: hematuria, proteinuria, in-hospital AKI, or prehospital AKI. AKI was defined according to the Kidney Disease Improving Global Outcomes (KDIGO) creatinine criteria. The primary outcome was death at the end of follow-up. The secondary outcome was progression to critical illness during the study period. RESULTS: A total of 555 patients were enrolled; 42% of the cases (229 of 549) were detected with any kidney injury, 33% of the cases (174 of 520) were detected with proteinuria, 22% of the cases (112 of 520) were detected with hematuria, and 6% of the cases (29 of 520) were detected with AKI. Of the 29 patients with AKI, 21 cases were recognized as in-hospital AKI, and eight were recognized as prehospital AKI. Altogether, 27 (5%) patients died at the end of follow-up. The death rate was 11% (20 of 174) in patients with proteinuria, 16% (18 of 112) in patients with hematuria, and 41% (12 of 29) in the AKI settings. Multivariable Cox regression analysis showed that proteinuria (hazard ratio, 4.42; 95% confidence interval, 1.22 to 15.94), hematuria (hazard ratio, 4.71; 95% confidence interval, 1.61 to 13.81), and in-hospital AKI (hazard ratio, 6.84; 95% confidence interval, 2.42 to 19.31) were associated with death. Among the 520 patients with noncritical illness at admission, proteinuria (hazard ratio, 2.61; 95% confidence interval, 1.22 to 5.56) and hematuria (hazard ratio, 2.50; 95% confidence interval, 1.23 to 5.08) were found to be associated with progression to critical illness during the study period. CONCLUSIONS: Kidney injury is common in coronavirus disease 2019, and it is associated with poor clinical outcomes. PODCAST: This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2020_09_18_CJN04780420.mp3.

Human amniotic epithelial cells ameliorate kidney damage in ischemia-reperfusion mouse model of acute kidney injury.

BACKGROUND: Acute kidney injury (AKI) is a common clinical disease with complex pathophysiology and limited therapeutic choices. This prompts the need for novel therapy targeting multiple aspects of this disease. Human amnion epithelial cell (hAEC) is an ideal stem cell source. Increasing evidence suggests that exosomes may act as critical cell-cell communicators. Accordingly, we assessed the therapeutic potential of hAECs and their derived exosomes (hAECs-EXO) in ischemia reperfusion mouse model of AKI and explored the underlying mechanisms. METHODS: The hAECs were primary cultured, and hAECs-EXO were isolated and characterized. An ischemic-reperfusion injury-induced AKI (IRI-AKI) mouse model was established to mimic clinical ischemic kidney injury with different disease severity. Mouse blood creatinine level was used to assess renal function, and kidney specimens were processed to detect cell proliferation, apoptosis, and capillary density. Macrophage infiltration was analyzed by flow cytometry. hAEC-derived exosomes (hAECs-EXO) were used to treat hypoxia-reoxygenation (H/R) injured HK-2 cells and mouse bone marrow-derived macrophages to evaluate their protective effect in vitro. Furthermore, hAECs-EXO were subjected to liquid chromatography-tandem mass spectrometry for proteomic profiling. RESULTS: We found that systematically administered hAECs could improve mortality and renal function in IRI-AKI mice, decrease the number of apoptotic cells, prevent peritubular capillary loss, and modulate kidney local immune response. However, hAECs showed very low kidney tissue integration. Exosomes isolated from hAECs recapitulated the renal protective effects of their source cells. In vitro, hAECs-EXO protected HK-2 cells from H/R injury-induced apoptosis and promoted bone marrow-derived macrophage polarization toward M2 phenotype. Proteomic analysis on hAECs-EXO revealed proteins involved in extracellular matrix organization, growth factor signaling pathways, cytokine production, and immunomodulation. These findings demonstrated that paracrine of exosomes might be the key mechanism of hAECs in alleviating renal ischemia reperfusion injury. CONCLUSIONS: We reported hAECs could improve survival and ameliorate renal injury in mice with IRI-AKI. The anti-apoptotic, pro-angiogenetic, and immunomodulatory capabilities of hAECs are at least partially, through paracrine pathways. hAECs-EXO might be a promising clinical therapeutic tool, overcoming the weaknesses and risks associated with the use of native stem cells, for patients with AKI.

Apocynin attenuates renal fibrosis via inhibition of NOXs-ROS-ERK-myofibroblast accumulation in UUO rats.

BACKGROUND: Oxidative stress has been identified as an important pathogenesis mechanism in the development of renal interstitial fibrosis in unilateral ureteral obstruction (UUO). Previous studies have demonstrated increased expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOXs) in response to UUO. We aimed to investigate whether NOXs activation was involved in the development of renal fibrosis in UUO by contribution to oxidative stress and the potential mechanism in the present study. METHODS: Apocynin, a NOXs inhibitor, was initiated immediately by gavage after UUO was performed on Wistar rats and continued until 7 days after UUO. Changes of markers of oxidative stress, renal macrophage infiltration and fibrosis, TGF-ß1 expression, NOXs expression and activity, and ERK activation were evaluated. RESULTS: Apocynin significantly attenuated the activity of NOXs, accompanied with decreased expression of NOX2, NOX4, and oxidative stress markers in the obstructed kidneys of UUO. Additionally, collagen deposition and renal fibrosis induced by UUO were attenuated by apocynin treatment. Furthermore, apocynin treatment significantly attenuated the phosphorylation of ERK, accumulation of myofibroblast and infiltration of macrophage in obstructed kidneys. No significant effect of apocynin on UUO-induced increased TGF-ß1 expression could be observed. And there was no significant change of anti-oxidants enzyme activities in the obstructed kidneys of apocynin-treated rats. CONCLUSIONS: These results suggested that apocynin might exert beneficial effects on renal fibrosis by inhibition of NOXs activation and subsequent reduction of oxidative stress, ERK activation, and myofibroblast accumulation in UUO rats. Targeting NOXs may serve as a therapeutic strategy for the treatment of renal fibrosis.