Injectable Multifunctional Composite Hydrogel as a Combination Therapy for Preventing Postsurgical Adhesion.

Postsurgical adhesion (PA) is a common and serious postoperative complication that affects millions of patients worldwide. However, current commercial barrier materials are insufficient to inhibit diverse pathological factors during PA formation, and thus, highly bioactive materials are needed. Here, this work designs an injectable multifunctional composite hydrogel that can serve as a combination therapy for preventing PA. In brief, this work reveals that multiple pathological events, such as chronic inflammatory and fibrotic processes, contribute to adhesion formation in vivo, and such processes can not be attenuated by barrier material (e.g., hydrogel) alone treatments. To solve this limitation, this work designs a composite hydrogel made of the cationic self-assembling peptide KLD2R and TGF-ß receptor inhibitor (TGF-ßRi)-loaded mesenchymal stem cell-derived nanovesicles (MSC-NVs). The resulting composite hydrogel displays multiple functions, including physical separation of the injured tissue areas, antibacterial effects, and local delivery and sustained release of anti-inflammatory MSC-NVs and antifibrotic TGF-ßRi. As a result, this composite hydrogel effectively inhibited local inflammation, fibrosis and adhesion formation in vivo. Moreover, the hydrogel also exhibits good biocompatibility and biodegradability in vivo. Together, the results highlight that this "all-in-one" composite hydrogel strategy may provide insights into designing advanced therapies for many types of tissue injury.

Macrophage-derived exosomal miR-195a-5p impairs tubular epithelial cells mitochondria in acute kidney injury mice.

Macrophages (Mφ) infiltration is a common characteristic of acute kidney injury (AKI). Exosomes-mediated cell communication between tubular epithelial cells (TECs) and Mφ has been suggested to be involved in AKI. Exosomes-derived from injured TECs could regulate Mφ polarization during AKI. However, little is known regarding how activated Mφ regulates kidney injury. To explore the role of activated Mφ in the AKI process, we revealed that Mφ-derived exosomes from AKI mice (ExosAKI ) caused mitochondria damage and induced TECs injury. Then, we detected the global miRNA expression profiles of MφNC and MφAKI and found that among the upregulated miRNAs, miR-195a-5p, which regulates mitochondria metabolism in cancer, was significantly increased in MφAKI . Due to the enrichment of miR-195a-5p in ExosAKI , the miR-195a-5p level in the kidney was elevated in AKI mice. More interestingly, based on the high expression of pri-miR-195a-5p in kidney-infiltrated Mφ, and the reduction of miR-195a-5p in kidney after depletion of Mφ in AKI mice, we confirmed that miR-195a-5p may be produced in infiltrated Mφ, and shuttled into TECs via ExosMφ . Furthermore, in vitro inhibition of miR-195a-5p alleviated the effect of ExosAKI induced mitochondrial dysfunction and cell injury. Consistently, antagonizing miR-195a-5p with a miR-195a-5p antagomir attenuated cisplatin-induced kidney injury and mitochondrial dysfunction in mice. These findings revealed that the Mφ exosomal miR-195a-5p derived from AKI mice played a critical pathologic role in AKI progression, representing a new therapeutic target for AKI.

Oleic acid improves hepatic lipotoxicity injury by alleviating autophagy dysfunction.

Lipotoxicity caused by excess free fatty acids, particularly saturated fatty acids (SFAs) such as palmitic acid (PA), is one of the most important pathogenesis of nonalcoholic fatty liver disease (NAFLD). However, unsaturated fatty acids (UFAs), such as oleic acid (OA), are nontoxic and can combat SFA-induced toxicity through alleviation of cell apoptosis, endoplasmic reticulum stress (ER stress) and lipids metabolism disorder. However, whether OA is able to regulate autophagy is largely unknown. So, this study aims to investigate the mechanism underlying OA mediated modulation of autophagy in hepatocytes and mice with NAFLD. In vitro, human hepatoma cell line HepG2 cells, human normal liver cells L-02 and mouse normal liver cells AML12 were treated with palmitic acid (PA)/tunicamycin (TM) or/and OA for 48 h. In vivo, C57/BL6 mice were fed with high fat diet (HFD) to induce NAFLD. And the HFD was partial replaced by olive oil to observe the protective effects of olive oil. We demonstrated that PA/TM impaired cell viability and induced cellular apoptosis in HepG2 cells and L-02 cells. Moreover, PA/TM induced autophagy impairment by reducing the nuclear translocation of transcription factor EB (TFEB) and inhibiting the activity of CTSB. However, OA substantially alleviated PA/TM induced cellular apoptosis and autophagy dysfunction in hepatocytes. Additionally, restoring autophagy function is able to reduce ER stress. Similarly, HFD for 20 weeks successfully established NAFLD model in C57/BL6 mice, and significant autophagy impairment were observed in liver tissues. Noteworthily, 30% replacement of HFD with olive oil had profoundly reversed NAFLD. It significantly impoved steatosis, and reduced autophagy dysfunction, ER stress and apoptosis in liver tissue. Conclusively, these data demonstrated that OA is able to effectively impove autophagy dysfunction under the context of both PA and ER stress inducer induced lipotoxicity, and OA mediated regulation of lysosome dysfunction through TFEB plays an important role, suggesting that the regulation of ER stress-autophagy axis is a critical mechanism in OA driven protection in NAFLD.

Comparison of Animal Models for the Study of Nonalcoholic Fatty Liver Disease.

Nonalcoholic fatty liver disease (NAFLD) is one of the most prevalent chronic liver diseases, and there is still no effective treatment for its advanced stage, nonalcoholic steatohepatitis (NASH). An ideal animal model of NAFLD/NASH is urgently needed for preclinical studies. However, the models reported previously are quite heterogeneous owing to differences in animal strains, feed formulations, and evaluation indicators, among others. In this study, we report 5 NAFLD mouse models we developed in previous studies and comprehensively compared their characteristics. The high-fat diet (HFD) model was time-consuming and characterized by early insulin resistance and slight liver steatosis at 12 weeks. However, inflammation and fibrosis were rare, even at 22 weeks. The high-fat, high-fructose, and high-cholesterol diet (FFC) exacerbates glucose and lipid metabolism disorders, showing distinct hypercholesterolemia, steatosis, and mild inflammation at 12 weeks. An FFC diet combined with streptozotocin (STZ) was a novel model that speeds up the process of lobular inflammation and fibrosis. The STAM model also used a combination of FFC and STZ but used newborn mice and showed the fastest formation of fibrosis nodules. The HFD model was appropriate for the study of early NAFLD. FFC combined with STZ accelerated the pathologic process of NASH and might be the most promising model for NASH research and drug development.

Programmable DNA Hydrogel Provides Suitable Microenvironment for Enhancing TSPCS Therapy in Healing of Tendinopathy.

Tendon stem/progenitor cells (TSPCs) therapy is a promising strategy for enhancing cell matrix and collagen synthesis, and regulating the metabolism of the tendon microenvironment during tendon injury repair. Nevertheless, the barren microenvironment and gliding shear of tendon cause insufficient nutrition supply, damage, and aggregation of injected TSPCs around tendon tissues, which severely hinders their clinical application in tendinopathy. In this study, a TSPCs delivery system is developed by encapsulating TSPCs within a DNA hydrogel (TSPCs-Gel) as the DNA hydrogel offers an excellent artificial extracellular matrix (ECM) microenvironment by providing nutrition for proliferation and protection against shear forces. This delivery method restricts TSPCs to the tendons, significantly extending their retention time. It is also found that TSPCs-Gel injections can promote the healing of rat tendinopathy in vivo, where cross-sectional area and load to failure of injured tendons in rats are significantly improved compared to the free TSPCs treatment group at 8 weeks. Furthermore, the potential healing mechanism of TSPCs-Gel is investigated by RNA-sequencing to identify a series of potential gene and signaling pathway targets for further clinical treatment strategies. These findings suggest the potential pathways of using DNA hydrogels as artificial ECMs to promote cell proliferation and protect TSPCs in TSPC therapy.

S-sulfhydration of SIRT3 combats BMSC senescence and ameliorates osteoporosis via stabilizing heterochromatic and mitochondrial homeostasis.

Senescence of bone marrow mesenchymal stem cells (BMSCs) is one of the leading causes of osteoporosis. SIRT3, an essential NAD-dependent histone deacetylase, is highly correlated with BMSC senescence-mediated bone degradation and mitochondrial/heterochromatic disturbance. S-sulfhydration of cysteine residues favorably enhances SIRT3 activity by forming persulfides. Nevertheless, the underlying molecular mechanism of SIRT3 S-sulfhydration on mitochondrial/heterochromatic homeostasis involved in BMSC senescence remains unknown. Here, we demonstrated that CBS and CSE, endogenous hydrogen sulfide synthases, are downregulated with BMSC senescence. Exogenous H2S donor NaHS-mediated SIRT3 augmentation rescued the senescent phenotypes of BMSCs. Conversely, SIRT3 deletion accelerated oxidative stress-induced BMSC senescence through mitochondrial dysfunction and the detachment of the heterochromatic protein H3K9me3 from the nuclear envelope protein Lamin B1. H2S-mediated SIRT3 S-sulfhydration modification rescued the disorganized heterochromatin and fragmented mitochondria induced by the S-sulfhydration inhibitor dithiothreitol, thus leading to elevated osteogenic capacity and preventing BMSC senescence. The antisenescence effect of S-sulfhydration modification on BMSCs was abolished when the CXXC sites of the SIRT3 zinc finger motif were mutated. In vivo, aged mice-derived BMSCs pretreated with NaHS were orthotopically transplanted to the ovariectomy-induced osteoporotic mice, and we proved that SIRT3 ameliorates bone loss by inhibiting BMSC senescence. Overall, our study for the first time indicates a novel role of SIRT3 S-sulfhydration in stabilizing heterochromatin and mitochondrial homeostasis in counteracting BMSC senescence, providing a potential target for the treatment of degenerative bone diseases.

Compact Combustion Mechanisms of Typical n-Alkanes Developed by the Minimized Reaction Network Method.

The existing combustion kinetic modeling method which aims at developing phenomenological combustion mechanisms characterized by multiple reactions confronts several challenges, including the conflicts between computing resources and mechanism scales during numerical simulation, etc. In order to address these issues, the minimized reaction network method for complex combustion system modeling based on the principle of simultaneous chemical equilibrium is proposed, which is aimed to develop combustion mechanisms with minimal reaction steps under a limited number of species. The concept of mechanism resolution is proposed in this method, and the reaction network with minimal reaction steps under a given mechanism resolution is constructed so that the scale of mechanisms is compressed greatly. Meanwhile, distinguishing from other mechanisms, the reversible form of elementary reactions is adopted and the classical two-parameter (A, Ea) Arrhenius equation fits the rate constants. Typical n-alkanes including n-butane, n-heptane, n-octane, n-decane, n-dodecane and n-hexadecane were taken as examples to indicate the development process of mechanisms and systematic kinetic validations were carried out. Results show that this method leads to very compact mechanisms with satisfactory accuracy, and it eliminates the process of mechanism reduction and is beneficial for mechanism optimization. This method and the derived kinetic mechanisms are hoped to contribute to combustion engineering applications.

Adiponectin gene therapy prevents islet loss after transplantation.

Significant pancreatic islet dysfunction and loss shortly after transplantation to the liver limit the widespread implementation of this procedure in the clinic. Nonimmune factors such as reactive oxygen species and inflammation have been considered as the primary driving force for graft failure. The adipokine adiponectin plays potent roles against inflammation and oxidative stress. Previous studies have demonstrated that systemic administration of adiponectin significantly prevented islet loss and enhanced islet function at post-transplantation period. In vitro studies indicate that adiponectin protects islets from hypoxia/reoxygenation injury, oxidative stress as well as TNF-α-induced injury. By applying adenovirus mediated transfection, we now engineered islet cells to express exogenous adiponectin gene prior to islet transplantation. Adenovirus-mediated adiponectin transfer to a syngeneic suboptimal islet graft transplanted under kidney capsule markedly prevented inflammation, preserved islet graft mass and improved islet transplant outcomes. These results suggest that adenovirus-mediated adiponectin gene therapy would be a beneficial clinical engineering approach for islet preservation in islet transplantation.

MLKL-mediated necroptosis is a target for cardiac protection in mouse models of type-1 diabetes.

BACKGROUND: Cardiomyocyte death contributes to cardiac pathology of diabetes. Studies have shown that the RIPK3/MLKL necroptosis signaling is activated in diabetic hearts. Deletion of RIPK3 was reported to attenuate myocardial injury and heart dysfunction in streptozocin (STZ)-induced diabetic mice, suggesting a potential role of necroptosis in diabetic cardiomyopathy. This study characterized cardiomyocyte necroptosis in diabetic hearts and investigated whether MLKL-mediated necroptosis is a target for cardiac protection in diabetes. METHODS: Type 1 diabetes was induced in RIPK3 knockout, MLKL knockout and wild-type mice. Akita Type-1 diabetic mice were injected with shRNA for MLKL. Myocardial function was assessed by echocardiography. Immuno-histological analyses determined cardiomyocyte death and fibrosis in the heart. Cultured adult mouse cardiomyocytes were incubated with high glucose in the presence of various drugs. Cell death and phosphorylation of RIPK3 and MLKL were analysed. RESULTS: We showed that the levels of phosphorylated RIPK3 and MLKL were higher in high glucose-stimulated cardiomyocytes and hearts of STZ-induced type-1 diabetic mice, akita mice and type-1 diabetic monkeys when compared to non-diabetic controls. Inhibition of RIPK3 by its pharmacological inhibitor or gene deletion, or MLKL deletion prevented high glucose-induced MLKL phosphorylation and attenuated necroptosis in cardiomyocytes. In STZ-induced type-1 diabetic mice, cardiomyocyte necroptosis was present along with elevated cardiac troponin I in serum and MLKL oligomerization, and co-localized with phosphorylated MLKL. Deletion of RIPK3 or MLKL prevented MLKL phosphorylation and cardiac necroptosis, attenuated serum cardiac troponin I levels, reduced myocardial collagen deposition and improved myocardial function in STZ-injected mice. Additionally, shRNA-mediated down-regulation of MLKL reduced cardiomyocyte necroptosis in akita mice. Interestingly, incubation with anti-diabetic drugs (empagliflozin and metformin) prevented phosphorylation of RIPK3 and MLKL, and reduced cell death in high glucose-induced cardiomyocytes. CONCLUSIONS: We have provided evidence that cardiomyocyte necroptosis is present in diabetic hearts and that MLKL-mediated cardiomyocyte necroptosis contributes to diabetic cardiomyopathy. These findings highlight MLKL-mediated necroptosis as a target for cardiac protection in diabetes.

Mitochondrial transfer from mesenchymal stem cells to macrophages restricts inflammation and alleviates kidney injury in diabetic nephropathy mice via PGC-1α activation.

Mesenchymal stem cells (MSCs) have fueled ample translation for treatment of immune-mediated diseases. Our previous study had demonstrated that MSCs could elicit macrophages (Mφ) into anti-inflammatory phenotypes, and alleviate kidney injury in diabetic nephropathy (DN) mice via improving mitochondrial function of Mφ, yet the specific mechanism was unclear. Recent evidence indicated that MSCs communicated with their microenvironment through exchanges of mitochondria. By a coculture system consisting of MSCs and Mφ, we showed that MSCs-derived mitochondria (MSCs-Mito) were transferred into Mφ, and the mitochondrial functions were improved, which contributed to M2 polarization. Furthermore, we found that MSCs-Mito transfer activated peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α)-mediated mitochondrial biogenesis. In addition, PGC-1α interacted with TFEB in high glucose-induced Mφ, leading to the elevated lysosome-autophagy, which was essential to removal of damaged mitochondria. As a result, in Mφ, the mitochondrial bioenergy and capacity to combat inflammatory response were enhanced. Whereas, the immune-regulatory activity of MSCs-Mito was significantly blocked in PGC-1α knockdown Mφ. More importantly, MSCs-Mito transfer could be observed in DN mice, and the adoptive transfer of MSCs-Mito educated Mφ (MφMito ) inhibited the inflammatory response and alleviated kidney injury. However, the kidney-protective effects of MφMito were abolished when the MSCs-Mito was impaired with rotenone, and the similar results were also observed when MφMito were transfected with sipgc-1α before administration. Collectively, these findings suggested that MSCs elicited Mφ into anti-inflammatory phenotype and ameliorated kidney injury through mitochondrial transfer in DN mice, and the effects were relied on PGC-1α-mediated mitochondrial biogenesis and PGC-1α/TFEB-mediated lysosome-autophagy.

WSNEAP: An Efficient Authentication Protocol for IIoT-Oriented Wireless Sensor Networks.

With the development of the Industrial Internet of Things (IIoT), industrial wireless sensors need to upload the collected private data to the cloud servers, resulting in a large amount of private data being exposed on the Internet. Private data are vulnerable to hacking. Many complex wireless-sensor-authentication protocols have been proposed. In this paper, we proposed an efficient authentication protocol for IIoT-oriented wireless sensor networks. The protocol introduces the PUF chip, and uses the Bloom filter to save and query the challenge-response pairs generated by the PUF chip. It ensures the security of the physical layer of the device and reduces the computing cost and communication cost of the wireless sensor side. The protocol introduces a pre-authentication mechanism to achieve continuous authentication between the gateway and the cloud server. The overall computational cost of the protocol is reduced. Formal security analysis and informal security analysis proved that our proposed protocol has more security features. We implemented various security primitives using the MIRACL cryptographic library and GMP large number library. Our proposed protocol was compared in-depth with related work. Detailed experiments show that our proposed protocol significantly reduces the computational cost and communication cost on the wireless sensor side and the overall computational cost of the protocol.

Complement C5 activation promotes type 2 diabetic kidney disease via activating STAT3 pathway and disrupting the gut-kidney axis.

Diabetic kidney disease (DKD) is a severe DM complication. While complement C5 up-regulation and gut dysbiosis are found in T2DM, their roles in DKD are unclear. Here, we investigated the effect of C5 on the gut microbiota during DKD development. Renal C5a/C5a receptor (C5aR) expression changes were measured in T2DM patients and db/db mice. Db/db mice were treated with a C5aR antagonist (C5aRA), and renal function, gut microbiota and renal genome changes were analysed. The effects of C5a and short-chain fatty acids (SCFAs) on the signal transducer and activator of transcription 3 (STAT3) pathway were examined in vitro. C5a was up-regulated in glomerular endothelial cells (GECs) of T2DM patients and db/db mice. Although glucose and lipid metabolism were unchanged, C5aR blockade alleviated renal dysfunction, ECM deposition, macrophage infiltration and proinflammatory factor expression in db/db mice. C5aRA partly reversed the declines in gut microbiota diversity and abundance and gut SCFA levels in db/db mice. C5aRA down-regulated the expression of many immune response-related genes, such as STAT3, in db/db mouse kidneys. C5aRA and SCFAs suppressed C5a-induced STAT3 activation in human renal glomerular endothelial cells (HRGECs). Based on our results, C5 hyperactivation promotes DKD by activating STAT3 in GECs and impairing the gut-kidney axis, suggesting that this hyperactivation is a potential target for the treatment of DKD.

Indispensable role of mitochondria in maintaining the therapeutic potential of curcumin in acute kidney injury.

Acute kidney injury (AKI) is a serious disease for which effective therapeutic agents are required. The capacity of curcumin (CUR) to resolve renal inflammation/oxidative stress and mitochondrial damage has been reported, but crosstalk between these effects and the consequence of this crosstalk remain elusive. In this study, a hypoxia/reoxygenation (H/R)-induced renal tubular epithelial cell (TEC) injury model and an ischaemia/reperfusion (I/R)-induced mouse AKI model were treated with CUR with or without mitochondrial inhibitors (rotenone and FCCP) or siRNA targeting mitochondrial transcription factor A (TFAM). Changes in mitochondrial function, inflammation, the antioxidant system and related pathways were analysed. In vitro, CUR suppressed NFκB activation and cytokine production and induced NRF2/HO-1 signalling in TECs under H/R conditions. CUR treatment also reduced mitochondrial ROS (mtROS) and mitochondrial fragmentation and enhanced mitochondrial biogenesis, TCA cycle activity and ATP synthesis in damaged TECs. However, the anti-inflammatory and antioxidant effects of CUR in damaged TECs were markedly abolished upon mitochondrial disruption. In vivo, CUR treatment improved renal function and antioxidant protein (NRF2 and SOD2) expression and reduced oxidative stress (8-OHdG), tubular apoptosis/death, cytokine release/macrophage infiltration and mitochondrial damage in the kidneys of AKI mice. In vitro, the anti-inflammatory and antioxidant effects of CUR in damaged kidneys were impaired when mitochondrial function was disrupted. These results suggest mitochondrial damage is a driving factor of renal inflammation and redox imbalance. The therapeutic capacity of CUR in kidneys with AKI is primarily dependent on mitochondrial mechanisms; thus, CUR is a potential therapy for various diseases characterized by mitochondrial damage.

Mesenchymal stromal cells protect hepatocytes from lipotoxicity through alleviation of endoplasmic reticulum stress by restoring SERCA activity.

The aim of this study was to investigate how mesenchymal stromal cells (MSCs) modulate metabolic balance and attenuate hepatic lipotoxicity in the context of non-alcoholic fatty liver disease (NAFLD). In vivo, male SD rats were fed with high-fat diet (HFD) to develop NAFLD; then, they were treated twice by intravenous injections of rat bone marrow MSCs. In vitro, HepG2 cells were cocultured with MSCs by transwell and exposed to palmitic acid (PA) for 24 hours. The endoplasmic reticulum (ER) stressor thapsigargin and sarco/ER Ca2+ -ATPase (SERCA2)-specific siRNA were used to explore the regulation of ER stress by MSCs. We found that MSC administration improved hepatic steatosis, restored systemic hepatic lipid and glucose homeostasis, and inhibited hepatic ER stress in HFD-fed rats. In hepatocytes, MSCs effectively alleviated the cellular lipotoxicity. Particularly, MSCs remarkably ameliorated the ER stress and intracellular calcium homeostasis induced by either PA or thapsigargin in HepG2 cells. Additionally, long-term HFD or PA stimulation would activate pyroptosis in hepatocytes, which may contribute to the cell death and liver dysfunction during the process of NAFLD, and MSC treatment effectively ameliorates these deleterious effects. SERCA2 silencing obviously abolished the ability of MSCs against the PA-induced lipotoxicity. Conclusively, our study demonstrated that MSCs were able to ameliorate liver lipotoxicity and metabolic disturbance in the context of NAFLD, in which the regulation of ER stress and the calcium homeostasis via SERCA has played a key role.

Mesenchymal stem cells elicit macrophages into M2 phenotype via improving transcription factor EB-mediated autophagy to alleviate diabetic nephropathy.

Diabetic nephropathy (DN) is a leading cause of end-stage renal disease. Chronic inflammation is recognized as a key causal factor in the development and progression of DN, and the imbalance of M1/M2 macrophages (Mφ) contributes to this process. Mesenchymal stem cells (MSCs) have been reported to prevent renal injuries via immune regulation in diabetic models, but whether these benefits are owing to the regulation of Mφ, and the underlying signaling pathways are unknown. Here, we showed that MSCs elicited Mφ into M2 phenotype and prevented renal injuries in DN mice, but these effects were abolished when the Mφ were depleted by clodronate liposomes (Lipo-Clod), suggesting that Mφ were necessary for renal protection of MSCs in DN mice. Moreover, the MSCs promoted M2 polarization was attributable to the activation of transcription factor EB (TFEB) and subsequent restore of lysosomal function and autophagy activity in Mφ. Furthermore, in vivo adoptive transfer of Mφin vivo (Mφ from DN + MSCs mice) or MφMSCs (Mφ cocultured with MSCs in vitro) to DN mice improved renal function. While, TFEB knockdown in Mφ significantly abolished the protective role of MφMSCs . Altogether, these findings revealed that MSCs suppress inflammatory response and alleviate renal injuries in DN mice via TFEB-dependent Mφ switch.

Mechanistic insights into AMPK-SIRT3 positive feedback loop-mediated chondrocyte mitochondrial quality control in osteoarthritis pathogenesis.

Osteoarthritis (OA) is a major cause of disability in the elderly population and represents a significant public health problem and socioeconomic burden worldwide. However, no disease-modifying therapeutics are currently available for OA due to an insufficient understanding of the pathogenesis of this disability. As a unique cell type in cartilage, chondrocytes are essential for cartilage homeostasis and play a critical role in OA pathogenesis. Mitochondria are important metabolic centers in chondrocytes and contribute to cell survival, and mitochondrial quality control (MQC) is an emerging mechanism for maintaining cell homeostasis. An increasing number of recent studies have demonstrated that dysregulation of the key processes of chondrocyte MQC, which involve mitochondrial redox, biogenesis, dynamics, and mitophagy, is associated with OA pathogenesis and can be regulated by the chondroprotective molecules 5' adenosine monophosphate-activated protein kinase (AMPK) and sirtuin 3 (SIRT3). Moreover, AMPK and SIRT3 regulate each other, and their expression and activity are always consistent in chondrocytes, which suggests the existence of an AMPK-SIRT3 positive feedback loop (PFL). Although the precise mechanisms are not fully elucidated and need further validation, the current literature indicates that this AMPK-SIRT3 PFL regulates OA development and progression, at least partially by mediating chondrocyte MQC. Therefore, understanding the mechanisms of AMPK-SIRT3 PFL-mediated chondrocyte MQC in OA pathogenesis might yield new ideas and potential targets for subsequent research on the OA pathomechanism and therapeutics.

Transcripts 202 and 205 of IL-6 confer resistance to Vemurafenib by reactivating the MAPK pathway in BRAF(V600E) mutant melanoma cells.

BRAF mutations occur in approximately 50% of melanoma patients. The mutated BRAF kinase continuously activates the mitogen-activated protein kinase (MAPK) pathway to promote cell growth and proliferation. Vemurafenib as a specific BRAF inhibitor can significantly prolong progression-free survival in melanoma patients. However, most patients developed resistance to Vemurafenib after 6 months. The mechanism of drug resistance is not yet fully understood. In this study, we found that proteins secreted by drug-resistant cells protect sensitive cells from Vemurafenib. By RNA-seq, we compared differentially expressed genes between resistant and sensitive cells. We demonstrated that drug-resistant cells secrete more IL-6 protein than sensitive cells. For the first time, we found that IL-6 expressed by drug-resistant cells consists of the following transcripts: IL6-201, IL6-202 and IL6-205. We confirmed that it is the IL6-202 and IL6-205 transcripts that confer drug resistance to Vemurafenib by reactivating the MAPK pathway while IL6-201 is not responsible for the resistance in A375 melanoma cells. Neutralizing IL-6 significantly increased the sensitivity of drug-resistant cells to Vemurafenib. Overall, these results reveal a new mechanism of drug resistance in melanoma.

Mesenchymal stem cells alleviate rat diabetic nephropathy by suppressing CD103+ DCs-mediated CD8+ T cell responses.

Diabetic nephropathy (DN) as a kind of serious microvascular complication of Diabetes Mellitus (DM) usually causes the end-stage of renal disease (ESRD). Studies have demonstrated that CD103+ dendritic cells (DCs) exhibited a renal pathogenic effect in murine chronic kidney disease (CKD). Mesenchymal stem cells (MSCs) can alleviate DN and suppress the DCs maturation. To explore the role of CD103+ DCs and the potential mechanisms underlying MSCs-mediated protective effects in DN, we used bone marrow MSCs (BM-MSCs) to treat DN rats. MSCs transplantation considerably recovered kidney function and diminished renal injury, fibrosis and the population of renal CD103+ DCs in DN rat. The MSCs-treated DN rats had decreased mRNA expression levels of interleukin (IL)1ß, IL6, tumour necrosis factor alpha (TNF-α), monocyte chemotactic protein 1 (MCP-1) and reduced CD8 T cell infiltration in the kidney. MSCs significantly down-regulated the genes expression of transcription factors (Basic leucine zipper transcriptional factor ATF-like 3, Batf3 and DNA-binding protein inhibitor ID-2, Id2) and FMS-like tyrosine kinase-3 (Flt3) which are necessary for CD103+ DCs development. The protective effect of MSCs may be partly related to their immunosuppression of CD8+ T cell proliferation and activation mediated by CD103+ DCs in the kidney of DN rats.

Peritoneal M2 macrophage transplantation as a potential cell therapy for enhancing renal repair in acute kidney injury.

Acute kidney injury (AKI) is a clinical condition that is associated with high morbidity and mortality. Inflammation is reported to play a key role in AKI. Although the M2 macrophages exhibit antimicrobial and anti-inflammatory activities, their therapeutic potential has not been evaluated for AKI. This study aimed to investigate the protective effect of peritoneal M2 macrophage transplantation on AKI in mice. The macrophages were isolated from peritoneal dialysates of mice. The macrophages were induced to undergo M2 polarization using interleukin (IL)-4/IL-13. AKI was induced in mice by restoring the blood supply after bilateral renal artery occlusion for 30 minutes. The macrophages were injected into the renal cortex of mice. The changes in renal function, inflammation and tubular proliferation were measured. The M2 macrophages were co-cultured with the mouse primary proximal tubular epithelial cells (PTECs) under hypoxia/reoxygenation conditions in vitro. The PTEC apoptosis and proliferation were analysed. The peritoneal M2 macrophages effectively alleviated the renal injury and inflammatory response in mice with ischaemia-reperfusion injury (IRI) and promoted the PTEC proliferation in vivo and in vitro. These results indicated that the peritoneal M2 macrophages ameliorated AKI by decreasing inflammatory response and promoting PTEC proliferation. Hence, the peritoneal M2 macrophage transplantation can serve as a potential cell therapy for renal diseases.

Mesenchymal stem cells alleviate palmitic acid-induced endothelial-to-mesenchymal transition by suppressing endoplasmic reticulum stress.

High levels of plasma free fatty acids (FFAs) lead to endothelial dysfunction (ED), which is involved in the pathogenesis of metabolic syndrome, diabetes, and atherosclerosis. Endoplasmic reticulum (ER) stress and endothelial-to-mesenchymal transition (EndMT) are demonstrated to be mechanistically related to endothelial dysfunction. Mesenchymal stem cells (MSCs) have exhibited an extraordinary cytoprotective effect on cellular lipotoxicity and vasculopathy. However, the underlying mechanisms have not been clearly defined. In the present study, we investigated whether MSCs could ameliorate palmitic acid (PA)-induced endothelial lipotoxicity by reducing ER stress and EndMT. We observed that MSC cocultures substantially alleviated PA-induced lipotoxicity in human umbilical vein endothelial cells (HUVECs). MSCs were able to restore the cell viability, increase tubule formation and migration ability, and decrease inflammation response and lipid deposition. Furthermore, PA caused endothelial-to-mesenchymal transition in HUVECs, which was abrogated by MSCs possibly through inhibiting ER stress. In addition, PA stimulated MSCs to secrete more stanniocalcin-1 (STC-1). Knocking down of STC-1 in MSCs attenuated their effects on PA-induced lipotoxicity in HUVECs. In vivo, MSC transplantation alleviated dyslipidemia and endothelial dysfunction in high-fat diet-fed Sprague-Dawley rats. MSC-treated rats showed reduced expressions of ER stress-related genes in aortas and suppressed expressions of EndMT-related proteins in rat aortic endothelial cells. Overall, our findings indicated that MSCs were able to attenuate endothelial lipotoxicity through inhibiting ER stress and EndMT, in which STC-1 secreted from MSCs may play a critical role.