Tubular epithelial cells derived-exosomes containing CD26 protects mice against renal ischemia/reperfusion injury by maintaining proliferation and dissipating inflammation.

Ischemia-reperfusion injury (IR) is the leading cause of acute kidney injury (AKI). No effective drugs to treat IR-related AKI are currently available. Recent pre-clinical trials have evaluated the therapeutic potential of extracellular vesicles-exosomes to chronic kidney disease. Here, we found exosomes derived from the tubular epithelial cell in IR condition (ExoIR) enriched CD26, compared with control (ExoNormal). Tracking exosomes in vivo certified tubular epithelial cell uptake exosomes. We have isolated exosomes with overexpression of CD26 (ExoCD26+) from culture media from tubular epithelial cell line transferred by adenovirus vectors. After administration of exosomes (100 mg) or bovine serum albumin (BSA, equivalent protein control) in IR or sham operation mice after 72 h via tail vein injection, the renal function impairment and histology injury were relived in mice receiving ExoCD26+. Immunofluorescence staining with proliferating cell nuclear antigen revealed ExoCD26+ recovered proliferation of cells partly after IR injury. Cell cycle modulator, p53 and p21 were upregulated in IR mice receiving BSA control, ExoNormal, and ExoIR. ExoCD26+ significantly blunt this protein upregulation. Inflammatory cell infiltration and chemokine receptor (CXCR4) were dissipated in IR mice receiving ExoCD26+. Downstream chemokine of CXCR4, stromal derived factor-1 (SDF1) also decreased after administration of ExoCD26+ in IR mice. Finally, ExoCD26+ suppressed inundant collagenⅠ expression in IR kidney. In conclusion, Tubular epithelial cells derived-exosomes containing CD26 might be one of the therapy modes for IR-AKI by maintaining proliferation and dissipating inflammation.

Urinary exosomal CD26 is associated with recovery from acute kidney injury in intensive care units: a prospective cohort study.

OBJECTIVES: Currently there is no validated method to predict renal reversal and recovery after acute kidney injury (AKI). As exosomes have the potential for AKI prognosis and CD26 is involved in the mechanisms in AKI, this study aims to investigate whether urinary exosomal CD26 is associated with renal-related outcomes and explore its prospect as a novel prognosis biomarker. METHODS: This was a single-center, prospective cohort study. A total of 133 AKI patients and 68 non-AKI patients admitted to ICU in Qilu Hospital Shandong University from January 2017 to January 2018. Urine samples were collected at enrollment and the relative expression of CD26 (CD26 percentage) in urinary exosomes was examined, that was then categorized into a low-CD26 level and a high-CD26 level. RESULTS: CD26 percentage was significantly lower in the AKI cohort than in the control cohort. Within the AKI cohort, a high-CD26 level was associated with lower incidence of major adverse kidney events within 90 days, but higher incidence of reversal within 28 days. In AKI survivors, a high-CD26 level had a 4.67-, 3.50- and 4.66-fold higher odds than a low-CD26 level for early reversal, recovery and reversal, respectively, after adjustment for clinical factors. Prediction performance was moderate for AKI survivors but improved for non-septic AKI survivors. CONCLUSIONS: Urinary exosomal CD26 is associated with renal reversal and recovery from AKI and is thus a promising prognosis biomarker.

PTPN2 improved renal injury and fibrosis by suppressing STAT-induced inflammation in early diabetic nephropathy.

Diabetic nephropathy (DN) is a chronic inflammatory disease triggered by disordered metabolism. Recent studies suggested that protein tyrosine phosphatase non-receptor type 2 (PTPN2) could ameliorate metabolic disorders and suppress inflammatory responses. This study investigated PTPN2's role in modulating DN and the possible cellular mechanisms involved. In a mouse model combining hyperglycaemia and hypercholesterolaemia (streptozotocin diabetic, ApoE-/- mice), mice showed severe insulin resistance, renal dysfunction, micro-inflammation, subsequent extracellular matrix expansion and decreased expression of PTPN2. We found that mice treated with PTPN2 displayed reduced serum creatinine, serum BUN and proteinuria. PTPN2 gene therapy markedly attenuated metabolic disorders and hyperglycaemia. In addition, PTPN2 gene transfer significantly suppressed renal activation of signal transducers and activators of transcription (STAT), STAT-dependent pro-inflammatory and pro-fibrotic genes expression, and influx of lymphocytes in DN, indicating anti-inflammatory effects of PTPN2 by inhibiting the activation of STAT signalling pathway in vivo. Furthermore, PTPN2 overexpression inhibited the high-glucose induced phosphorylation of STAT, target genes expression and proliferation in mouse mesangial and tubuloepithelial cells, suggesting that the roles of PTPN2 on STAT activation was independent of glycaemic changes. Our results demonstrated that PTPN2 gene therapy could exert protective effects on DN via ameliorating metabolic disorders and inhibiting renal STAT-dependent micro-inflammation, suggesting its potential role for treatment of human DN.

STING deficiency alleviates ferroptosis through FPN1 stabilization in diabetic kidney disease.

Ferroptosis, a form of cell death driven by iron-dependent lipid peroxidation, has known as one of the most significant pathological processes involved in diabetic kidney disease (DKD). Stimulator of interferon genes (STING) has been demonstrated its potential in regulating ferroptosis, but the regulatory role in DKD mice and underlying mechanisms haven't been illustrated. To elucidate whether and how STING regulates ferroptosis in DKD, we detected the influence of STING on diabetic-related ferroptosis in a diabetic model and in erastin-induced renal tubular epithelial cells (RTECs). Our study demonstrated that STING was abnormally activated and promoted ferroptosis in DKD. STING deficiency alleviated renal pathologic damages and disfunction in diabetic mice via alleviating ferroptosis and reducing oxidative stress. Mechanismly, STING inhibition was shown to improve ferroptosis and reduce oxidative stress in erastin-induced RTECs. The disruption of ferroportin1 (FPN1) on the basis of STING inhibition abolished the improvements in ferroptosis and promoted reactive oxygen species (ROS) generation. Further, STING inhibition alleviated ferroptosis via stabilizing FPN1 protein level by decreasing ubiquitinated FPN1 for proteasomal degradation. In conclusion, STING deficiency protected against diabetic renal injury via alleviating ferroptosis through stabilizing FPN1 and reducing oxidative stress, providing a possible potential approach for the treatment of DKD.

Stimulator of interferon genes promotes diabetic sarcopenia by targeting peroxisome proliferator activated receptors γ degradation and inhibiting fatty acid oxidation.

BACKGROUND: Declined skeletal muscle mass and function are inevitable consequences of long-term diabetes and bring about many adverse events. Muscle fibre atrophy and interstitial fibrosis are major pathological manifestations of diabetic sarcopenia. Stimulator of interferon genes (STING) participates in various metabolic diseases. We aimed to explore whether and how STING regulates the above pathological manifestations of diabetic sarcopenia. METHODS: Wild-type and STINGgt/gt C57BL/6J mice and C2C12 myotubes were used to study the role of STING in the regulation of diabetic sarcopenia and the underlying mechanisms. RESULTS: STING was abnormally activated in diabetic muscles and in PA-treated myotubes (P < 0.01 for all parameters). The diabetic mice demonstrated decreased forelimb grip strength, lean mass, muscle weight and hanging impulse, which were improved by STING deficiency due to alleviated muscle fibre atrophy and interstitial fibrosis (P < 0.05 for all parameters). STING deficiency alleviated muscle fibre atrophy through the following mechanisms. Firstly, STING deficiency or inhibition increased the contents of pDRP1Ser616 , PINK1, Parkin and LC3-II, decreased p62 content, and increased the amount of mito-Keima fluorescent dots at 578 nm in diabetic state (P < 0.05 for all parameters), suggesting improved mitofission and mitophagy. Secondly, STING deficiency or inhibition increased the expression of pAKTSer473 and GLUT4 post-insulin change in diabetic state (P < 0.05 for all), indicating alleviated insulin resistance (IR). Mechanically, STING deficiency or inhibition increased peroxisome proliferator activated receptors γ (PPARγ) protein content by reducing the degradation of ubiquitinated PPARγ through the proteasome pathway and thus increased the expression of fatty acid oxidation (FAO)-related proteins in diabetic state (P < 0.05 for all parameters). Decreased expression of FAO-related proteins caused by PPARγ inhibition abolished the improvements in mitofission, mitophagy and IR achieved by STING inhibition in PA-treated myotubes and thus promoted muscle fibre atrophy (P < 0.05 for all parameters). STING deficiency alleviated interstitial fibrosis by decreasing TGFß1 expression in diabetic state and TGFß1 promoted the fibrogenic differentiation of fibro-adipogenic progenitors (P < 0.05 for all parameters). PPARγ inhibition abolished the effect of STING inhibition on reducing TGFß1 content in PA-treated myotubes (P < 0.01). CONCLUSIONS: STING deficiency exerted protective effects in diabetic sarcopenia by inhibiting the degradation of ubiquitinated PPARγ through the proteasome pathway and enhancing PPARγ-mediated FAO, which alleviated muscle fibre atrophy by promoting mitophagy and ameliorating IR, and alleviated interstitial fibrosis by reducing TGFß1 production and suppressing the fibrogenic differentiation of fibro-adipogenic progenitors.

Exercise Capacity Is Improved by Levosimendan in Heart Failure and Sarcopenia via Alleviation of Apoptosis of Skeletal Muscle.

BACKGROUND: Patients suffering from chronic heart failure (CHF) show an increased prevalence of sarcopenia. Levosimendan is an effective drug for the treatment of heart failure, but its effect on sarcopenia is still unclear. We aimed to explore whether levosimendan could enhance skeletal muscle contractibility, improve skeletal muscle atrophy, and thus improve exercise tolerance of individuals with heart failure. METHODS: C57BL6/J mice were used to establish the heart failure with sarcopenia model and injected of levosimendan. Mice were separated into control group, sham operation group, HF group, HF + solvent group, HF + levosimendan group, HF + sarcopenia group, HF + sarcopenia + solvent group, HF + sarcopenia + levosimendan group (n = 5-12). After the treatment, exercise capacity and cardiac function were evaluated. Muscle morphology, inflammation level and apoptosis levels were detected, in which mitochondrial function and oxidative stress level were also assessed. RESULT: Levosimendan could increase forelimb grip strength/body weight, hanging impulse, maximum running distance and time in mice with HF and sarcopenia (P < 0.0001 for all), and these improvements were independent of EF (P = 0.0019 for hanging impulse, P < 0.001 for forelimb grip strength/body weight and maximum running distance). Levosimendan directly increased the CSA of gastrocnemius in mice with HF and sarcopenia (P < 0.0001). After levosimendan injection, the proportion of slow muscle fibers increased (P < 0.0001), but this improvement of muscle fiber typing might be attributed to improved cardiac function (P > 0.05). Levosimendan also maintained mitochondrial membrane potential, decreased cleaved caspase-3 (P = 0.034), cleaved caspase-9 (P < 0.0001), Bax expression (P < 0.0001), and increased Bcl2 expression (P = 0.0036). This effect is independent of improved cardiac function (P = 0.028 for bax, P < 0.001 for cleaved caspase-9 and Bcl2). IL-6, TNF-α expression (P < 0.0001 for both) decreased, and SOD activity (P = 0.0038), GSH/GSSG ratio (P = 0.002) significantly increased in skeletal muscle after injection of levosimendan. The improvement in oxidative stress level was attributed to improved cardiac function (P > 0.05). CONCLUSION: Levosimendan reduce the loss of skeletal muscle mitochondrial membrane potential, decrease the apoptosis, alleviate the inflammation and oxidative stress, and ultimately improve the exercise capacity of mice with heart failure and sarcopenia. Therefore, levosimendan may be a potential drug for the treatment of heart failure with sarcopenia.

Pim1 knockout alleviates sarcopenia in aging mice via reducing adipogenic differentiation of PDGFRα+ mesenchymal progenitors.

BACKGROUND: Sarcopenia widely exists in elderly people and triggers numerous age-related events. The essential pathologic change lies in the increased intramuscular adipose tissue after aging with no exception to non-obese objects. Pim1 appears to be associated with adipogenic differentiation in recent studies, inspiring us to explore whether it regulates adipogenesis in aging muscles and affects sarcopenia. METHODS: Wild-type and Pim1 knockout C57/BL6J mice were randomized into young and old groups. Histo-pathological and molecular biological methods were applied to assess the intramuscular adipose tissue content, the atrophy and regeneration, and the expressions of Pim1 and adipogenic transcription factors. PDGFRα+ mesenchymal progenitors were separated and their replicative aging model were established. Different time of adipogenic induction and different amounts of Pim1 inhibitor were applied, after which the adipogenic potency were evaluated. The expressions of Pim1 and adipogenic transcription factors were measured through western blotting. RESULTS: The aging mice demonstrated decreased forelimb grip strength (P = 0.0003), hanging impulse (P < 0.0001), exhaustive running time (P < 0.0001), tetanic force (P = 0.0298), lean mass (P = 0.0008), and percentage of gastrocnemius weight in body weight (P < 0.0001), which were improved by Pim1 knockout (P = 0.0015, P = 0.0222, P < 0.0001, P = 0.0444, P = 0.0004, and P = 0.0003, respectively). To elucidate the mechanisms, analyses showed that Pim1 knockout decreased the fat mass (P = 0.0005) and reduced the intramuscular adipose tissue content (P = 0.0008) by inhibiting the C/EBPδ pathway (P = 0.0067) in aging mice, resulting in increased cross-sectional area of all and fast muscle fibres (P = 0.0017 and 0.0024 respectively), decreased levels of MuRF 1 and atrogin 1 (P = 0.0001 and 0.0329 respectively), and decreased content of Pax7 at the basal state (P = 0.0055). In vitro, senescent PDGFRα+ mesenchymal progenitors showed significantly increased the intracellular adipose tissue content (OD510) compared with young cells after 6 days of adipogenic induction (P < 0.0001). The Pim1 expression was elevated during adipogenic differentiation, and Pim1 inhibition significantly reduced the OD510 in senescent cells (P = 0.0040) by inhibiting the C/EBPδ pathway (P = 0.0047). CONCLUSIONS: Pim1 knockout exerted protective effects in sarcopenia by inhibiting the adipogenic differentiation of PDGFRα+ mesenchymal progenitors induced by C/EBPδ activation and thus reducing the intramuscular adipose tissue content in aging mice. These results provide a potential target for the treatment of sarcopenia.

Increased circulating erythrocyte-derived microparticles in patients with acute coronary syndromes.

Objective: This study is to explore the predictive value of erythrocyte-derived microparticles (ErMPs) in patients with acute coronary syndrome (ACS). Materials & methods: Total 305 subjects were enrolled and divided into the control group and ACS group. Flow cytometry was used to detect the ErMPs. The Gensini score was calculated based on the results of the coronary angiography. Results: Compared with that in the control group, the ErMPs concentration in the ACS group increased significantly and the concentration of ErMPs was correlated with the ACS risk. The concentration of ErMPs and the percentage of ErMPs were positively correlated with the Gensini score. Conclusion: ErMPs may be a new biomarker for predicting the ACS risk and the coronary artery disease severity.

Sarcopenia is attenuated by TRB3 knockout in aging mice via the alleviation of atrophy and fibrosis of skeletal muscles.

BACKGROUND: Sarcopenia causes several adverse events in elderly people. Muscle fibre atrophy and interstitial fibrosis are the main histopathological changes in sarcopenia and account for decreased muscle function. Tribbles homologue 3 (TRB3) was previously reported to exhibit age-related expression and play a vital role in cell proliferation, differentiation, and fibrosis. We aimed to investigate how TRB3 affects sarcopenia. METHODS: Wild-type and TRB3 knockout C57/BL6J mice were randomly divided into young and old groups. Exercise capacity was evaluated, and single-muscle function was detected by electrophysiological techniques, after which the mice were sacrificed to collect their gastrocnemius muscles for assessment of atrophy and fibrosis by histopathological and molecular biological methods. TRB3 expression, autophagy level, and MAPK signalling pathway activity were evaluated through western blotting. The interaction of TRB3 with P62 and the association between TRB3 and the MAPK signalling pathway were detected by co-immunoprecipitation. RESULTS: In aged mice, exercise capacity and cross-sectional area of skeletal muscle fibres were decreased significantly, whereas TRB3, atrophy-related markers atrogin 1 and MuRF 1, and interstitial fibrosis, including collagen volume fraction, contents of collagens I and III, and ratio of collagens I to III, were increased significantly (P < 0.05 for all). Following TRB3 knockout, the cross-sectional area of muscle fibres, mainly fast fibres, was elevated (P < 0.05 for both), the atrogin 1 expression was decreased (P = 0.0163), and the corresponding tetanic force of fast muscles was increased (P = 0.0398). Conversely, interstitial fibrosis was substantially decreased and exercise capacity was significantly increased in the knockout mice. In terms of the underlying mechanisms, the autophagy receptor p62 was markedly increased and the MAPK signalling pathway was activated in aged skeletal muscles, which might be attributed to the interaction of TRB3 with p62 and MAPKKs, including MEK1/MEK2, MEK3/MEK6, and MEK4/MKK4. Notably, TRB3 knockout reduced the accumulation of p62 and LC3 (P < 0.05 for both), decreased the phosphorylation of JNK (P = 0.0015), and increased p38 phosphorylation (P = 0.0021). CONCLUSIONS: TRB3 knockout in mice attenuated muscle fibre atrophy and reduced skeletal muscle fibrosis by increasing autophagy and inhibiting the MAPK signalling pathway. Correspondingly, in aged knockout mice, exercise capacity was improved. Interfering with TRB3 expression in aged skeletal muscles may serve as a target for the prevention and treatment of age-related sarcopenia.

Impact of Perioperative Levosimendan Administration on Risk of Bleeding After Cardiac Surgery: A Meta-analysis of Randomized Controlled Trials.

BACKGROUND: Levosimendan, a calcium sensitizer and potassium channel opener, has been demonstrated to improve myocardial function without increasing oxygen consumption and to show protective effects in other organs. Recently, a prospective, randomized controlled trial (RCT) revealed an association between levosimendan use and a possible increased risk of bleeding postoperatively. Levosimendan's anti-platelet effects have been shown in in vitro studies. Current studies do not provide sufficient data to support a relation between perioperative levosimendan administration and increased bleeding risk. PURPOSE: Our goal was to investigate the relation between perioperative levosimendan administration and increased bleeding risk using a meta-analysis study design. METHODS: The PubMed, Ovid, EMBASE and Cochrane Library databases were searched for relevant RCTs before July 1, 2019. The outcome parameters included reoperation secondary to increased bleeding in the postoperative period, the amount of postoperative recorded blood loss, and the need for transfusion of packed red blood cells (RBCs) and other blood products. RESULTS: A total of 1160 patients in nine RCTs (576 in the levosimendan group and 584 in the control group) were included according to our inclusion criteria. Analysis showed that perioperative levosimendan administration neither increased the rate of reoperation secondary to bleeding nor increased the amount of postoperative chest tube drainage when compared with the control group. In terms of blood product transfusion, levosimendan did not influence the requirement for RBC transfusion, platelet transfusion nor fresh frozen plasma (FFP) transfusion. Levosimendan also did not shorten or prolong the aortic cross-clamp time or the cardiopulmonary bypass time. CONCLUSION: The analyzed parameters, including reoperations due to bleeding, postoperative chest drainage and the requirement for blood products, revealed that levosimendan did not increase postoperative bleeding risk. More studies with a larger sample size are needed to address a more reliable conclusion due to study limitations.

Effects of Levosimendan on Patients with Heart Failure Complicating Acute Coronary Syndrome: A Meta-Analysis of Randomized Controlled Trials.

BACKGROUND: The prognosis for patients with heart failure (HF), including cardiogenic shock (CS), complicating acute coronary syndrome (ACS) remains poor. OBJECTIVE: This study aimed to review the relevant literature and evaluate whether levosimendan was associated with better clinical outcomes in these patients. METHODS: We searched PubMed, EMBASE, and the Cochrane library databases for randomized controlled trials that investigated levosimendan compared with any control in patients with HF/CS complicating ACS. RESULTS: A total of 1065 patients from nine trials were included in this study. Analysis showed that levosimendan significantly reduced total mortality and the incidence of worsening HF. In patients with HF-ACS, levosimendan was associated with reduced mortality. In patients with CS-ACS, no significant difference was observed between the two groups. Levosimendan contributed to significantly reduced mortality when compared with placebo, but no significant reduction was seen compared with dobutamine. Compared with controls, levosimendan decreased pulmonary capillary wedge pressure and systemic vascular resistance and increased cardiac index, with no significant difference observed between the groups in terms of heart rate. Levosimendan non-significantly increased the risk of hypotension but did not increase the risk of ischemic episodes, sinus tachycardia, atrial fibrillation, or ventricular arrhythmias. CONCLUSION: Levosimendan appears to be a promising drug to reduce mortality and worsening HF in patients with HF/CS-ACS. It appears to provide hemodynamic benefit and was associated with an increased risk of hypotension.