Background. This study evaluated whether the change in the renin-angiotensin system (RAS) is associated with arterial aging in mice. Methods. Histologic changes and expressions of transforming growth factor-β (TGF-β), collagen IV, fibronectin, angiotensin II (Ang II), angiotensin-converting enzyme (ACE), angiotensin-converting enzyme 2 (ACE2), angiotensin II type 1 receptor (AT1R), angiotensin II type 2 receptor (AT2R), prorenin receptor (PRR), Mas receptor (MasR), endothelial nitric oxide synthase (eNOS), NADPH oxidase 2 and oxidase 4 (Nox2 and Nox4), 8-hydroxy-2′-deoxyguanosine (8-OHdG), 3-nitrotyrosine, and superoxide dismutase 1 and dismutase 2 (SOD1 and SOD2) were measured in the thoracic aortas from 2-month-old, 12-month-old, and 24-month-old C57/BL6 mice. Results. Twenty-four-month-old mice showed significantly increased aortic media thickness and expressions of TGF-β, collagen IV, and fibronectin, compared to 2-month-old and 12-month-old mice. The expressions of PRR, ACE, and Ang II, and AT1R-positive area significantly increased, whereas expressions of ACE2 and MasR and AT2R-positive area decreased with age. The expressions of phosphorylated serine1177-eNOS, SOD1, and SOD2 decreased, and the 8-OHdG-positive area and the 3-nitrotyrosine-positive area increased with age. The expression of Nox2 significantly increased with age, but that of Nox4 did not change. Conclusions. The enhanced PRR-ACE-Ang II-AT1R axis and reduced ACE2-MasR axis were associated with arterial aging in mice.

Background. Two important issues in the aging kidney are mitochondrial dysfunction and oxidative stress. An Nrf2 activator, resveratrol, is known to have various effects. Resveratrol may prevent inflammation and oxidative stress by activating Nrf2 and SIRT1 signaling. We examined whether resveratrol could potentially ameliorate the cellular condition, such as renal injury due to cellular oxidative stress and mitochondrial dysfunction caused by aging. Methods. Male 18-month-old C57BL/6 mice were used. Resveratrol (40 mg/kg) was administered to aged mice for 6 months. We compared histological changes, oxidative stress, and aging-related protein expression in the kidney between the resveratrol-treated group (RSV) and the control group (cont). We performed experiments using small-interfering RNAs (siRNAs) for Nrf2 and SIRT1 in cultured HK2 cells. Results. Resveratrol improved renal function, proteinuria, histological changes and inflammation in aging mice. Also, expression of Nrf2-HO-1-NOQ-1 signaling and SIRT1-AMPK-PGC-1α signaling was increased in the RSV group. Transfection with Nrf2 and SIRT1 siRNA prevented resveratrol-induced anti-oxidative effect in HK2 cells in media treated with H 2 O 2 . Conclusions. Activation of the Nrf2 and SIRT1 signaling pathways ameliorated oxidative stress and mitochondrial dysfunction. Pharmacological targeting of Nrf2 signaling molecules may reduce the pathologic changes of aging in the kidney.

The renin-angiotensin system (RAS), especially the angiotensin II (Ang II)/angiotensin II type 1 receptor (AT1R) axis, plays an important role in the aging process of the kidney, through increased tissue reactive oxygen species production and progressively increased oxidative stress. In contrast, the angiotensin 1-7 (Ang 1-7)/Mas receptor (MasR) axis, which counteracts the effects of Ang II, is protective for end-organ damage. To evaluate the ability of resveratrol (RSV) to modulate the RAS in aging kidneys, eighteen-month-old male C57BL/6 mice were divided into two groups that received either normal mouse chow or chow containing resveratrol, for six months. Renal expressions of RAS components, as well as pro- and antioxidant enzymes, were measured and mouse kidneys were isolated for histopathology. Resveratrol-treated mice demonstrated better renal function and reduced albuminuria, with improved renal histologic findings. Resveratrol suppressed the Ang II/AT1R axis and enhanced the AT2R/Ang 1-7/MasR axis. Additionally, the expression of nicotinamide adenine dinucleotide phosphate oxidase 4, 8-hydroxy-2′-deoxyguanosine, 3-nitrotyrosine, collagen IV, and fibronectin was decreased, while the expression of endothelial nitric oxide synthase and superoxide dismutase 2 was increased by resveratrol treatment. These findings demonstrate that resveratrol exerts protective effects on aging kidneys by reducing oxidative stress, inflammation, and fibrosis, through Ang II suppression and MasR activation.

Background The Korean Society of Nephrology (KSN) has maintained a nationwide end-stage renal disease (ESRD) registry data from Korean Renal Data System (KORDS) since 1985, as the representative registry of ESRD patients in Korea. This review is aimed to update the status of domestic ESRD and to provide evidence on the direction of dialysis therapy. Methods The KORDS Committee of KSN has collected data on dialysis centers and patients through an online registry program, and the data from 1986 to 2019 were analyzed. Results The incidence and prevalence of ESRD patients in Korea are increasing. The ESRD population numbered more than 100,000 in 2019, doubling during the 10 years since 2010. The proportion of diabetes mellitus as a major cause of ESRD seems to have reached a plateau. The increasing number of elderly dialysis patients is a constant trend, with more than half for the proportion of patients older than 65 years old in 2019. All-cause mortality decreased for the last approximately 20 years, regardless of sex, age, and cause of ESRD. The 5-year patient survival rate in both hemodialysis and peritoneal dialysis increased from 2001 to 2013. Since 2013, the patient survival rates in peritoneal dialysis were similar to those in hemodialysis. Cardiovascular complications were the leading cause of death in ESRD patients. Conclusion The incidence and prevalence of Korean ESRD patients have increased over time, although patient survival has also steadily increased. The establishment of a surveillance method to address the major cause of mortality in ESRD patients will help improve outcomes.

Toxic megacolon is a rare clinical complication of fulminant Clostridium difficile infection. The mortality rate of fulminant C. difficile infection is reported to be as high as 50%. Fecal microbiota transplantation is a highly effective treatment in patients with recurrent or refractory C. difficile infection. However, there are few published articles on the use of such transplantation for fulminant C. difficile infection. Here, we report on a patient with toxic megacolon complicated by C. difficile infection who was treated successfully with fecal microbiota transplantation.

Thrombotic microangiopathy (TMA) is defined by specific clinical characteristics, including microangiopathic hemolytic anemia, thrombocytopenia, and pathologic evidence of endothelial cell damage, as well as the resulting ischemic end-organ injuries. A variety of clinical scenarios have features of TMA, including infection, pregnancy, malignancy, autoimmune disease, and medications. These overlapping manifestations hamper differential diagnosis of the underlying pathogenesis, despite recent advances in understanding the mechanisms of several types of TMA syndrome. Atypical hemolytic uremic syndrome (aHUS) is caused by a genetic or acquired defect in regulation of the alternative complement pathway. It is important to consider the possibility of aHUS in all patients who exhibit TMA with triggering conditions because of the incomplete genetic penetrance of aHUS. Therapeutic strategies for aHUS are based on functional restoration of the complement system. Eculizumab, a monoclonal antibody against the terminal complement component 5 inhibitor, yields good outcomes that include prevention of organ damage and premature death. However, there remain unresolved challenges in terms of treatment duration, cost, and infectious complications. A consensus regarding diagnosis and management of TMA syndrome would enhance understanding of the disease and enable treatment decision-making.

IntroductionComplement binding activity of donor-specific HLA antibodies (DSA) has been suggested as a new tool to stratify immunologic risk in kidney transplantation (KT). The objective of this study was to evaluate the clinical implication of C1q/C3d binding activity of de novo DSA (dnDSA) in KT recipients.Material and methodsA total of 161 pretransplant DSA-negative recipients were monitored for dnDSA at the time of biopsy. C1q/C3d binding activities of dnDSA were assessed using C1qScreen assay (One lambda, USA) and Lifecodes C3d detection assay (Immucor, USA), respectively. Clinical outcomes including biopsy-proven antibody mediated rejection (AMR), C4d detection and post-biopsy graft survival were investigated.ResultsDe-novo DSAs were detected in fifty-four (33.5%) patients (HLA class I only, n = 19; class II only, n = 29; both class I and II, n = 6). Of them, complement binding activities were detected in 26 (48.1%) patients, including 17 C1q+ and 24 C3d+ patients. Both C1q and C3d positivity were associated with increased mean fluorescence intensity values of dnDSA. Complement binding activity of dnDSA enhanced the incidence of AMR (25.0% in C1q-C3d-, 36.4% in C1q+/C3d- or C1q-/C3d+, and 60.0% in C1q+/C3d+ patients) (P <0.001). The incidence of AMR was not different between patients with C1q+ and those with C3d+ dnDSA (64.7%, 11/17 versus 45.8%, 11/24, P = 0.238). In comparison between C1q and C3d assay according to HLA specificity, C1q+ HLA class I ± II dnDSA was the best predictor for AMR (odds ratio: 27.2). C1q+/C3d+ dnDSA was associated with more C4d deposition in allograft tissue and inferior post-biopsy graft survival. Clinical outcomes were not significantly different between C1q+ and C3d+ dnDSA-positive patients.ConclusionDetection of complement binding activity using both C1q and C3d assays can be a further prognostic marker for predicting AMR and allograft outcome in dnDSA+ kidney transplant patients.

Background/AimsThe true incidence of aristolochic acid nephropathy (AAN) is thought to be underestimated because numerous ingredients known or suspected to contain aristolochic acid (AA) are used in traditional medicine in Korea.MethodsWe collected data on cases of AAN since 1996 via a database in Korea. We evaluated the year of AAN development, route to obtaining AA-containing herbal medicine, gender, reason for taking AA-containing herbal medicine, clinical manifestations, histological findings, phytochemical analysis, and prognosis of patients with AAN.ResultsData on 16 cases of AAN were collected. Thirteen cases developed AAN before and three cases after the prohibition of AA-containing herbal medicine by the Korea Food and Drug Administration. Patients were prescribed AA-containing herbal medicine from oriental clinics or had purchased it from traditional markets. AAN was distributed in all age groups. Young females were most commonly exposed to AA-containing herbal medicine for slimming purposes and postpartum health promotion, while older adults took AA-containing compounds for the treatment of chronic diseases. The most common symptoms presented at hospitalization were nausea and vomiting, and acute kidney injury was accompanied by Fanconi syndrome in almost half of the patients. Phytochemical analysis of AA in herbal medicine was available in six cases. Progression to end stage renal disease (ESRD) was observed in seven patients (43.8%), and five patients (31.3%) had progressed to ESRD within 6 months of diagnosis.ConclusionsOur report shows that patients were still exposed to AA-containing herbal medicine and that there is a possibility of underdiagnosis of AAN in Korea. A stronger national supervision system of herbal ingredients and remedies in oriental medicine is needed to prevent AAN.