IL-17C neutralization protects the kidney against acute injury and chronic injury.

BACKGROUND: Interleukin-17C (IL-17C), a member of the IL-17 cytokine family, plays a pathogenic role in kidney diseases. Our previous studies have shown that pre-administration of IL-17C neutralizing antibody attenuated acute kidney injury (AKI, a common acute inflammation associated renal disease). In this study, we explored whether post-ischemia reperfusion (IR) of IL-17C blockade has therapeutic effects on AKI and whether IL-17C is involved in the pathogenesis of diabetic nephropathy (DN), a major type of chronic inflammation-associated kidney disease. METHODS: 12-week-old male C57BL/6JGpt mice were treated with IL-17C neutralizing antibody or normal IgG control antibody at 3 h after reperfusion. Renal injury, inflammation, and oxidative stress were assessed. Additionally, we examined renal IL-17C expression in patients with DN and db/db mice and evaluated albuminuria, mesangial matrix accumulation and podocyte loss in db/db mice with IL-17C neutralization. Knockdown of NF-κB p65 using siRNA, and blocking Hypoxia-inducible factor-1α (HIF-1α) using YC-1 in mice and HIF-1α Decoy in HK2 cells were investigated to explore the possible signaling pathway involved in IL-17C regulation. FINDINGS: We found that delayed IL-17C neutralization had similar reno-protective effects on renal ischemia-reperfusion injury (IRI). Additionally, renal IL-17C expression was increased in patients with DN and db/db mice, while IL-17C blockade significantly attenuated DN, accompanied with blunted albuminuria, mesangial matrix accumulation, and podocyte loss. Moreover, IL-17C neutralization significantly repressed the expression of downstream pro-inflammatory cytokines, inflammatory cell infiltration, and Th17/IL-17A activation both in mice with renal IRI and DN. Mechanistical studies demonstrated that hypoxia or high glucose-induced IL-17C up-regulation was predominantly mediated by NF-κB pathway. INTERPRETATION: IL-17C participates in the pathogenesis of AKI and DN and inhibition of IL-17C shows potential as a therapeutic strategy for AKI and DN. FUNDING: The National Natural Science Foundation of China (81770741, 81700601 and 81870504).

A FoxA2+ long-term stem cell population is necessary for growth plate cartilage regeneration after injury.

Longitudinal bone growth, achieved through endochondral ossification, is accomplished by a cartilaginous structure, the physis or growth plate, comprised of morphologically distinct zones related to chondrocyte function: resting, proliferating and hypertrophic zones. The resting zone is a stem cell-rich region that gives rise to the growth plate, and exhibits regenerative capabilities in response to injury. We discovered a FoxA2+group of long-term skeletal stem cells, situated at the top of resting zone, adjacent the secondary ossification center, distinct from the previously characterized PTHrP+ stem cells. Compared to PTHrP+ cells, FoxA2+ cells exhibit higher clonogenicity and longevity. FoxA2+ cells exhibit dual osteo-chondro-progenitor activity during early postnatal development (P0-P28) and chondrogenic potential beyond P28. When the growth plate is injured, FoxA2+ cells expand in response to trauma, and produce physeal cartilage for growth plate tissue regeneration.

IL-17C has a pathogenic role in kidney ischemia/reperfusion injury.

Cytokines are necessary to trigger the inflammatory response in kidney ischemia/reperfusion injury. Interleukin-17C (IL-17C), a unique member of the IL-17 family, is a cytokine produced by epithelial cells implicated in host defense and autoimmune diseases. However, little is known about the role of IL-17C in acute kidney injury. We investigated this and found that IL-17C was significantly increased in kidney biopsies of patients and mice with acute kidney injury. Exposure to hypoxia induced upregulation of IL-17C in kidney tubular epithelial cells. To further investigate the role of IL-17C, kidney ischemia/reperfusion injury was induced in mice. Inhibition of IL-17C action with a neutralizing antibody or IL-17 receptor E (IL-17RE) knockout attenuated tubular injury, kidney oxidative stress, and kidney inflammation. Mechanistically, both IL-17C neutralization and IL-17RE knockout attenuated TH17 activation and IL-17A expression in kidneys of mice with acute kidney injury. TNF-α and IL-1ß, downstream cytokines of IL-17C, were also reduced in IL-17C antibody pretreated and IL-17RE knockout mice. Additionally, IL-17C knockdown with siRNA decreased hypoxia-induced inflammation in kidney tubular cells and silencing IL-17RE abrogated the effects of IL-17C in kidney tubular cells. Thus, IL-17C may participate in the inflammatory response of acute kidney injury and inhibition of IL-17C or blockade of IL-17 RE may be a novel therapeutic strategy for the treatment of acute kidney injury.

A protective role of renalase in diabetic nephropathy.

Renalase, a recently discovered secreted flavoprotein, exerts anti-apoptotic and anti-inflammatory effects against renal injury in acute and chronic animal models. However, whether Renalase elicits similar effects in the development of diabetic nephropathy (DN) remains unclear. The studies presented here tested the hypothesis that Renalase may play a key role in the development of DN and may have therapeutic potential for DN. Renalase expression was measured in human kidney biopsies with DN and in kidneys of db/db mice. The role of Renalase in the development of DN was examined using a genetically engineered mouse model: Renalase knockout mice with db/db background. The renoprotective effects of Renalase in DN was evaluated in db/db mice with Renalase overexpression. In addition, the effects of Renalase on high glucose-induced mesangial cells were investigated. Renalase was down-regulated in human diabetic kidneys and in kidneys of db/db mice compared with healthy controls or db/m mice. Renalase homozygous knockout increased arterial blood pressure significantly in db/db mice while heterozygous knockout did not. Renalase heterozygous knockout resulted in elevated albuminuria and increased renal mesangial expansion in db/db mice. Mesangial hypertrophy, renal inflammation, and pathological injury in diabetic Renalase heterozygous knockout mice were significantly exacerbated compared with wild-type littermates. Moreover, Renalase overexpression significantly ameliorated renal injury in db/db mice. Mechanistically, Renalase attenuated high glucose-induced profibrotic gene expression and p21 expression through inhibiting extracellular regulated protein kinases (ERK1/2). The present study suggested that Renalase protected against the progression of DN and might be a novel therapeutic target for the treatment of DN.

Long Noncoding RNA: Genomics and Relevance to Physiology.

The mammalian cell expresses thousands of long noncoding RNAs (lncRNAs) that are longer than 200 nucleotides but do not encode any protein. lncRNAs can change the expression of protein-coding genes through both cis and trans mechanisms, including imprinting and other types of transcriptional regulation, and posttranscriptional regulation including serving as molecular sponges. Deep sequencing, coupled with analysis of sequence characteristics, is the primary method used to identify lncRNAs. Physiological roles of specific lncRNAs can be examined using genetic targeting or knockdown with modified oligonucleotides. Identification of nucleic acids or proteins with which an lncRNA interacts is essential for understanding the molecular mechanism underlying its physiological role. lncRNAs have been reported to contribute to the regulation of physiological functions and disease development in several organ systems, including the cardiovascular, renal, muscular, endocrine, digestive, nervous, respiratory, and reproductive systems. The physiological role of the majority of lncRNAs, many of which are species and tissue specific, remains to be determined. © 2019 American Physiological Society. Compr Physiol 9:933-946, 2019.

MiR-192-5p in the Kidney Protects Against the Development of Hypertension.

MicroRNA miR-192-5p is one of the most abundant microRNAs in the kidney and targets the mRNA for ATP1B1 (ß1 subunit of Na+/K+-ATPase). Na+/K+-ATPase drives renal tubular reabsorption. We hypothesized that miR-192-5p in the kidney would protect against the development of hypertension. We found miR-192-5p levels were significantly lower in kidney biopsy specimens from patients with hypertension (n=8) or hypertensive nephrosclerosis (n=32) compared with levels in controls (n=10). Similarly, Dahl salt-sensitive (SS) rats showed a reduced abundance of miR-192-5p in the renal cortex compared with congenic SS.13BN26 rats that had reduced salt sensitivity (n=9; P<0.05). Treatment with anti-miR-192-5p delivered through renal artery injection in uninephrectomized SS.13BN26 rats exacerbated hypertension significantly. Mean arterial pressure on a 4% NaCl high-salt diet at day 14 post anti-miR-192-5p treatment was 16 mm Hg higher than in rats treated with scrambled anti-miR (n=8 and 6; P<0.05). Similarly, Mir192 knockout mice on the high-salt diet treated with Ang II (angiotensin II) for 14 days exhibited a mean arterial pressure 22 mm Hg higher than wild-type mice (n=9 and 5; P<0.05). Furthermore, protein levels of ATP1B1 were higher in Dahl SS rats than in SS.13BN26 rats. Na+/K+-ATPase activity increased in the renal cortex of SS.13BN26 rats 9 days posttreatment with anti-miR-192-5p compared with that of control anti-miR treated rats. Intrarenal knockdown of ATP1B1 attenuated hypertension in SS.13BN26 rats with intrarenal knockdown of miR-192-5p. In conclusion, miR-192-5p in the kidney protects against the development of hypertension, which is mediated, at least in part, by targeting Atp1b1.

MicroRNA-214-3p in the Kidney Contributes to the Development of Hypertension.

BACKGROUND: In spite of extensive study, the mechanisms for salt sensitivity of BP in humans and rodent models remain poorly understood. Several microRNAs (miRNAs) have been associated with hypertension, but few have been shown to contribute to its development. METHODS: We examined miRNA expression profiles in human kidney biopsy samples and rat models using small RNA deep sequencing. To inhibit an miRNA specifically in the kidney in conscious, freely moving rats, we placed indwelling catheters to allow both renal interstitial administration of a specific anti-miR and measurement of BP. A rat with heterozygous disruption of the gene encoding endothelial nitric oxide synthase (eNOS) was developed. We used bioinformatic analysis to evaluate the relationship between 283 BP-associated human single-nucleotide polymorphisms (SNPs) and 1870 human miRNA precursors, as well as other molecular and cellular methods. RESULTS: Compared with salt-insensitive SS.13BN26 rats, Dahl salt-sensitive (SS) rats showed an upregulation of miR-214-3p, encoded by a gene in the SS.13BN26 congenic region. Kidney-specific inhibition of miR-214-3p significantly attenuated salt-induced hypertension and albuminuria in SS rats. miR-214-3p directly targeted eNOS. The effect of miR-214-3p inhibition on hypertension and albuminuria was abrogated in SS rats with heterozygous loss of eNOS. Human kidney biopsy specimens from patients with hypertension or hypertensive nephrosclerosis showed upregulation of miR-214-3p; the gene encoding miR-214-3p was one of several differentially expressed miRNA genes located in proximity to human BP-associated SNPs. CONCLUSIONS: Renal miR-214-3p plays a functional and potentially genetic role in the development of hypertension, which might be mediated in part by targeting eNOS.

Antithrombin â ¢ is a Novel Predictor for Contrast Induced Nephropathy After Coronary Angiography.

BACKGROUND/AIMS: Antithrombin Ⅲ (AT Ⅲ) is an important endogenous anticoagulant and has strong anti-inflammatory properties. Low ATⅢ activity is considered to be a predictor of poor outcomes in several conditions, including acute kidney injury after cardiac surgery. However, the association between the ATⅢ level and the occurrence of contrast induced nephropathy (CIN) has not been elucidated. In this study, our aim was to identify the potential predictive value of ATⅢ for CIN. METHODS: We enrolled a total of 460 patients who underwent coronary angiography (CAG) from January 2015 to December 2016 in coronary care units (CCU). ATⅢ activity in plasma collected before CAG was measured and <75% was considered low activity according to reference values. A cross-sectional study on CIN after CAG was conducted and the risk factors were analyzed. CIN was diagnosed according to the KDIGO guideline. RESULTS: Of these 460 patients undergoing CAG, 125 (27.17%) progressed to CIN. The incidence of CIN was significantly higher in patients with low ATⅢ activity compared to patients with normal ATⅢ activity (Pearson's chi-squared test P=0.002). As ATⅢ activity declined, the prevalence of CIN progressively increased, with the highest value (58.8%) in patients with an ATⅢ activity <60%. Moreover, the ATⅢ activity was significantly lower in CIN patients than in non-CIN patients (84.43±16.3% vs. 92.14±13.94%, P<0.001). After multivariable analysis, ATⅢ activity <75% remained a significant independent predictor of CIN (OR 2.207,95%CI [1.29-3.777]; P=0.004) as well as baseline serum creatinine (OR 1.009,95%CI [1.001-1.016]; P=0.026). CONCLUSIONS: Patients with low ATⅢ activity had a higher risk of developing CIN after CAG. The initial ATⅢ activity may be a novel independent predictor for CIN.

Antithrombin III Attenuates AKI Following Acute Severe Pancreatitis.

BACKGROUND: Antithrombin III (ATIII), the predominant coagulation factor inhibitor, possesses anti-inflammatory properties and exerts renoprotective effects on renal ischemia-reperfusion injury in animal models. However, the ATIII's protective effects of ATIII on acute kidney injury (AKI) following severe acute pancreatitis (SAP) need to be confirmed. METHODS: We assessed the association between ATIII activities and the incidence of AKI in patients with SAP, and explored therapeutic effects and potential mechanisms of ATIII on kidney injury in sodium taurocholate induced SAP rat model. Rats were intravenously injected with ATIII (500 µg/kg) before or after the induction of SAP. RESULTS: The results demonstrated ATIII did not attenuate pancreatic injury, but significantly ameliorate renal dysfunction and renal histological injury. ATIII administration alleviated renal inflammation response, oxidative stress, and cell apoptosis. Moreover, ATIII attenuated tumor necrosis factor α (TNFα)-stimulated intercellular cell adhesion molecule 1(ICAM-1) and monocyte chemotactic protein 1 (MCP-1) upregulation in cultured renal tubular epithelial cells. CONCLUSION: ATIII appears to ameliorate SAP-induced kidney injury by inhibiting inflammation, oxidative stress, and apoptosis. ATIII supplementation may have a potential prophylactic and therapeutic effect on SAP induced AKI.

Antithrombin III prevents progression of chronic kidney disease following experimental ischaemic-reperfusion injury.

Acute kidney disease (AKI) leads to increased risk of progression to chronic kidney disease (CKD). Antithrombin III (ATIII) is a potent anticoagulant with anti-inflammatory properties, and we previously reported that insufficiencies of ATIII exacerbated renal ischaemia-reperfusion injury (IRI) in rats. In this study, we examined the characteristic of AKI-CKD transition in rats with two distinct AKI models. Based on our observation, left IRI plus right nephrectomy (NX-IRI) was used to determine whether ATIII had therapeutic effects in preventing CKD progression after AKI. It was observed that NX-IRI resulted in significant functional and histological damage at 5 weeks after NX-IRI compared with sham rats, which was mitigated by ATIII administration. Besides, we noticed that ATIII administration significantly reduced NX-IRI-induced interstitial fibrosis. Consistently, renal expression of collagen-1, α-smooth muscle actin and fibronectin were substantial diminished in ATIII-administered rats compared with un-treated NX-IRI rats. Furthermore, the beneficial effects of ATIII were accompanied with decreased M1-like macrophage recruitment and down-regulation of M1-like macrophage-dependent pro-inflammatory cytokines such as tumour necrosis factor α, inducible nitric oxide synthase and interleukin-1ß, indicating that ATIII prevented AKI-CKD transition via inhibiting inflammation. Overall, ATIII shows potential as a therapeutic strategy for the prevention of CKD progression after AKI.

Tanshinone IIA attenuates renal damage in STZ-induced diabetic rats via inhibiting oxidative stress and inflammation.

Oxidative stress and inflammation have been demonstrated to be involved in the onset and promotion of diabetic nephropathy (DN).Tanshinone IIA (Tan) possesses both antioxidant and anti-inflammatory properties. Here, the aim of the present study was to explore whether Tan could attenuate renal damage in the rats with streptozotocin (STZ)-induced diabetes and its potential mechanisms. Tan was gavaged to STZ-induced diabetic rats at the dose of 10mg/kg once a day for 12 weeks. Tan treatment significantly attenuated albuminuria and renal histopathology in diabetic rats. Besides, Tan treatment also effectively inhibited oxidative stress and inflammatory reaction in the kidneys of diabetic rats. Our study provided evidence that the protective effect of Tan on diabetes-induced renal injury is associated with inhibition of oxidative stress and inflammation. Tan may be a potential candidate for the treatment of DN.

Sulodexide Protects Contrast-Induced Nephropathy in Sprague-Dawley Rats.

BACKGROUND: Sulodexide is a powerful antithrombin agent with reno-protective property. However, whether it has beneficial effects on Contrast-Induced Nephropathy (CIN) remained elusive. In the current study, we evaluated the therapeutic effects of Sulodexide on CIN and investigated the potential mechanisms. METHODS: CIN model was induced by intravenous injection of indomethacin, followed by Ioversol and L-NAME. Sprague-Dawley rats were divided into 4 groups: control group, CIN group, CIN+vehicle group (CIN rats pretreated with vehicle) and CIN+ Sulodexide (CIN rats pretreated with Sulodexide). Sulodexide or an equivalent volume of vehicle was intravenously delivered 30 min before the induction of CIN. All the animals were sacrificed at 24h after CIN and tissues were harvested to evaluate renal injury, kidney oxidative stress and apoptosis levels. Plasma antithrombin III (ATIII) activities were also measured. RESULTS: Compared to the untreated CIN group, improved renal function, reduced tubular injury, decreased levels of oxidative stress and apoptosis were observed in CIN rats receiving Sulodexide injection. In addition, we also found that ATIII activity was significantly higher in Sulodexide-administered group than that in vehicle-injected CIN rats. For in vitro studies, HK2 cells were exposed to Ioversol and the cyto-protective effects of Sulodexide were also determined. Sulodexide pretreatment protected HK2 cells against the cytotoxicity of Ioversol via inhibiting caspase-3 activity. Preincubation with Sulodexide could also attenuate H2O2-induced increases in ROS, apoptosis and caspase-3 levels. CONCLUSIONS: Taken together, Sulodexide could protect against CIN through activating ATIII, and inhibiting oxidative stress, inflammation and apoptosis.