MiR-21 alleviates renal tubular epithelial cells injury induced by ischemia by targeting TLR4.

Renal ischemia is the initial stage of kidney damage, leading to mitochondrial metabolism disorders and cell necrosis. In this study, we aimed to investigate the biological functions and potential mechanisms of miR-21 in protecting renal tubular epithelial cells from oxidative stress and apoptosis following oxygen glucose deprivation (OGD). Following an OGD injury, miR-21 levels increased in HK-2 renal tubular epithelial cells. Overexpression of miR-21 decreased the protein expressions of cleaved caspase-3, BAX, P53, cell apoptosis and increased Bcl-2 expression in HK-2 cells with OGD injury. In vivo studies found that miR-21 agomir reduced renal tissue apoptosis, while miR-21 antagomir increased it. In addition, overexpression of miR-21 reduced levels of reactive oxygen species (ROS), malondialdehyde (MDA) and lactate dehydrogenase (LDH) in HK-2 cells with OGD injury. However, miR-21 inhibition exhibited the opposite effect. A dual-luciferase reporter assay demonstrated that miR-21 directly regulates Toll-like receptor 4 (TLR4) by targeting the 3'-UTR of TLR4 mRNA. Overexpression of miR-21 led to decreased TLR4 protein expression, and TLR4 knockdown was shown to greatly increase AKT activity in HK-2 cells by in vitro kinase assay. Additionally, TLR4 knockdown promoted AKT phosphorylation and hypoxia-inducible factor-1α (HIF-1α) expression, while TLR4 overexpression inhibited these processes. Furthermore, AKT activation abolished the effect of TLR4 on HIF-1α, while AKT inhibition decreased the expression of TLR4 on HIF-1α in TLR4 knockdown HK-2 cells. Further study revealed that HIF-1α inhibition abolished the protective effect of miR-21 overexpression on ROS, LDH levels and cell apoptosis in HK-2 cells after OGD injury, which is indicated by increased levels of ROS and LDH, as well as increased cell apoptosis after HIF-1α inhibition in miR-21-treated HK-2 cells. In conclusion, miR-21 defends OGD-induced HK-2 cell injury via the TLR4/AKT/HIF-1α axis.

Evaluation of Renal Impairment in Patients with Diabetic Kidney Disease by Integrated Chinese and Western Medicine.

OBJECTIVE: To investigate the factors related to renal impairment in patients with diabetic kidney disease (DKD) from the perspective of integrated Chinese and Western medicine. METHODS: Totally 492 patients with DKD in 8 Chinese hospitals from October 2017 to July 2019 were included. According to Kidney Disease Improving Global Outcomes (KDIGO) staging guidelines, patients were divided into a chronic kidney disease (CKD) 1-3 group and a CKD 4-5 group. Clinical data were collected, and logistic regression was used to analyze the factors related to different CKD stages in DKD patients. RESULTS: Demographically, male was a factor related to increased CKD staging in patients with DKD (OR=3.100, P=0.002). In clinical characteristics, course of diabetes >60 months (OR=3.562, P=0.010), anemia (OR=4.176, P<0.001), hyperuricemia (OR=3.352, P<0.001), massive albuminuria (OR=4.058, P=0.002), atherosclerosis (OR=2.153, P=0.007) and blood deficiency syndrome (OR=1.945, P=0.020) were factors related to increased CKD staging in patients with DKD. CONCLUSIONS: Male, course of diabetes >60 months, anemia, hyperuricemia, massive proteinuria, atherosclerosis, and blood deficiency syndrome might indicate more severe degree of renal function damage in patients with DKD. (Registration No. NCT03865914).

Comparison of two fluid solutions for resuscitation in a rabbit model of crush syndrome.

BACKGROUND: Crush syndrome is a common injury, the main characteristics of which include acute kidney injury. However, there is still lack of reliable animal model of crush syndrome, and it also remains controversial as to which type of fluid should be chosen as a more appropriate treatment option for prevention and treatment of acute kidney injury. METHODS: The rabbits were crushed at the lower limbs for 6 h with 36 times the body weight, which means the pressure of each leg was also 36 times the body weight. Fluid resuscitation was performed from 1 h prior to the end of the crush treatment until 24 h after the reperfusion. Tissue, blood and urine samples were collected at predetermined time points before and after reperfusion. Twelve rabbits in each group were taken for survival observation for 72 h. RESULTS: The model group showed elevated serum creatine kinase, aspartate aminotransferase, alanine aminotransferase, and K(+) level, reduced serum Ca(2+) level and Na(+) level, and increased serum creatinine and blood urea nitrogen levels, neutrophil gelatinase-associated lipocalin, and kidney injury molecule-1 (p < 0.05). The 0.9 % normal saline (SAL) group and SAL plus 6 % hydroxyethyl starch 130/0.4 SAL/HES group showed reduced serum creatinine and blood urea nitrogen levels (p < 0.05). The SAL/HES group also showed reduced serum IL-6 and IL-10 levels (p < 0.05). The 72 h survival rate of the SAL/HES group was higher than that of the model group (p < 0.05). CONCLUSION: The rabbit model of crush syndrome showed clinical features consistent with those of crush syndrome. There was no significant difference in the ability of preventing AKI after a crush injury between the two fluid solutions, while SAL/HES can improve the survival rate.

Proximal tubule toll-like receptor 4 expression linked to inflammation and apoptosis following hypoxia/reoxygenation injury.

BACKGROUND: Toll-like receptor 4 (TLR4) plays a key role in mediating kidney damage during ischemia/reperfusion (I/R) injury, and its expression is enhanced following renal I/R injury. Our study focused on TLR4 silencing-mediated downstream antiapoptotic pathways during hypoxia/reoxygenation (H/R) and investigated whether TLR4 overexpression exacerbates the renal damage induced by I/R injury. METHODS: Proximal tubule epithelial cells (PTECs) were isolated and H/R injury mediated by ATP depletion, and replenishment was performed to mimic in vivo I/R injury. PTECs were transfected with either TLR4 siRNA or TLR4-overexpressing vectors to determine the contribution of TLR4 to H/R injury-induced apoptosis and inflammatory response. RESULTS: H/R injury significantly enhanced PTEC apoptosis (p < 0.01) and the production of tumor necrosis factor (TNF)-α and interleukin (IL)-8; however, TLR4 silencing significantly reversed these effects (p < 0.05). Moreover, compared to PTECs or PTECs-siCon exposed to H/R injury, overexpression of TLR4 further upregulated TNF-α and IL-8 (p < 0.05), but did not enhance apoptosis. The expression of cytochrome C and caspases 3, 8, and 9 was decreased in the siTLR4 group compared to controls after H/R injury, whereas TLR4 silencing did not alter CHOP expression. TLR4 overexpression failed to promote the expression of cytochrome C and caspases 3, 8, and 9, and reduced the expression of CHOP and GPR78. CONCLUSIONS: Knockdown of TLR4 could protect PTECs from H/R injury via inhibiting mitochondrial and death receptor pathways. TLR4 overexpression did not increase PTEC apoptosis induced by H/R injury due in part to the downregulation of CHOP.

Mesenchymal stem cells ameliorate sepsis-associated acute kidney injury in mice.

OBJECTIVE: Significant progress has been made in critical care medicine during the past several decades. However, the mortality rate is still high in patients with sepsis, especially with acute kidney injury (AKI). Mesenchymal stem cells (MSCs) possess an ability to ameliorate renal injury from ischemia-reperfusion, but it is still unknown whether they have the ability to reduce sepsis-associated AKI. METHODS: Male C57BL/6 mice underwent cecal ligation and puncture operation to induce sepsis and then received either normal saline or MSCs (1 × 10 cells intravenously) 3 h after surgery. RESULTS: Within 24 h after cecal ligation and puncture operation, the septic mice developed kidney injury and exhibited a higher mortality. Treatment with MSCs decreased serum creatinine and blood urea nitrogen levels and improved recovery of tubular function. mRNA levels of interleukin 6 (IL-6), IL-17, tumor necrosis factor α, interferon γ, CXCL1, CXCL2, CXCL5, CCL2, and CCL3 in kidney tissue were dramatically decreased after MSC treatment. Neutrophil infiltration in kidney and blood bacterial loads were attenuated after MSC injection. Moreover, mice treated with MSCs had a higher survival rate than the saline treatment group. Injected MSCs were mainly localized in the lungs, spleen, and abdominal cavity lymph node, but not in the kidneys. CONCLUSIONS: Treatment with MSCs can alleviate sepsis-associated AKI and improve survival in mice with polymicrobial sepsis. These effects may be mediated by the inhibition of IL-17 secretion and balance of the proinflammatory and anti-inflammatory states. Mesenchymal stem cells may be a potential new therapeutic agent for the prevention or reduction of sepsis-associated AKI.

Antithrombotic drug therapy for IgA nephropathy: a meta analysis of randomized controlled trials.

BACKGROUND: Antithrombotic agents, including antiplatelet agents, anticoagulants and thrombolysis agents, have been widely used in the management of immunoglobulin A (IgA) nephropathy in Chinese and Japanese populations. To systematically evaluate the effects of antithrombotic agents for IgA nephropathy. METHODS: Data sources consisted of MEDLINE, EMBASE, the Cochrane Library, Chinese Biomedical Literature Database (CBM), Chinese Science and Technology Periodicals Databases (CNKI) and Japana Centra Revuo Medicina (http://www.jamas.gr.jp) up to April 5, 2011. The quality of the studies was evaluated from the intention to treat analysis and allocation concealment, as well as by the Jadad method. Meta-analyses were performed on the outcomes of proteinuria and renal function. RESULTS: Six articles met the predetermined inclusion criteria. Antithrombotic agents showed statistically significant effects on proteinuria (p<0.0001) but not on the protection of renal function (p=0.07). The pooled risk ratio for proteinuria was 0.53, [95% confidence intervals (CI): 0.41-0.68; I(2)=0%] and for renal function it was 0.42 (95% CI 0.17-1.06; I(2)=72%). Subgroup analysis showed that dipyridamole was beneficial for proteinuria (p=0.0003) but had no significant effects on protecting renal function. Urokinase had statistically significant effects both on the reduction of proteinuria (p=0.0005) and protecting renal function (p<0.00001) when compared with the control group. CONCLUSION: Antithrombotic agents had statistically significant effects on the reduction of proteinuria but not on the protection of renal function in patients with IgAN. Urokinase had statistically significant effects both on the reduction of proteinuria and on protecting renal function. Urokinase was shown to be a promising medication and should be investigated further.