Mangiferin inhibits lipopolysaccharide-induced epithelial-mesenchymal transition (EMT) and enhances the expression of tumor suppressor gene PER1 in non-small cell lung cancer cells

Non-small cell lung cancer (NSCLC) is often complicated by pulmonary infection, which affects treatment and prognosis. Bacterial lipopolysaccharide (LPS) is an effective stimulator of inflammatory cytokine production, and previous studies have reported that LPS promotes tumor invasion and metastasis. Mangiferin is a plant-derived C-glucosylxanthone with many biological activities, such as antioxidation and anti-inflammation. This research mainly explored the mechanism of its antitumor activities on LPS-induced A549, NCI-H460, and NCI-H520 NSCLC cells. We determined that mangiferin exhibits growth inhibiting activity against LPS-induced NSCLC cells through the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. In addition, mangiferin reversed the LPS-induced downregulation of E-cadherin (epithelial marker); conversely, it significantly inhibited the expression of raised vimentin (mesenchymal markers). Moreover, the ability of NSCLC cells to migrate, as evidenced by the wound healing and transwell migration assays, and the expression of CXCR4 increased by LPS were significantly repressed by mangiferin. In addition, mangiferin markedly mediated protein levels of PER1 and NLRP3 in LPS-induced NSCLC cells and reduced the secretion of IL-1β. These results indicate that mangiferin is not only a remarkable anti-inflammatory compound but also an antitumor agent; thus, it has the potential for being developed into anti-inflammatory and antitumor drugs in the future.

Effect of Exercise Training on Exercise Tolerance and Level of Oxidative Stress for Head and Neck Cancer Patients Following Chemotherapy

Background

Chemotherapy decreases fitness performance via repression of cardiopulmonary function and oxidative stress. This study was designed to investigate whether exercise intervention could improve exercises capacity and reduce systemic oxidative stress in patients with head and neck (H&N) cancer receiving chemotherapy.

Methods

This is a single-center study. Forty-two H&N cancer patients who were undergoing chemotherapy were recruited in this study. An 8-week exercise intervention was performed by conducting the combination of aerobic and resistance exercise 3 days a week. The exercise training was conducted by a physiotherapist. The exercise capacity and exercise responses were measured from blood pressure (BP) and heart rate (HR). Oxidative stress markers from human plasma, such as total antioxidant capacity, 8-hydroxy-2'-deoxyguanosine, malondialdehyde, and carbonyl content, were tested by activity kits.

Results

We provide compelling evidence that exercise training ameliorated exercise responses and increased exercise capacity by repressing resting BP and increasing 1- and 3-min BP recovery. We also found the resting HR was reduced, and the 1- and 3-min HR recovery was increased after exercise training. In addition, the rating of perceived exertion after the peak exercise was reduced after exercise intervention. We also found that exercise training repressed oxidative stress markers by elevation of total antioxidant capacity and suppression of 8-OHd and carbonyl content in plasma.

Discussion

We clearly demonstrate that exercise can promote exercise capacity and reduce oxidative stress in H&N cancer patients receiving chemotherapy, which might guide new therapeutic approaches for cancer patients, especially those undergoing chemotherapy.

Injectable thermosensitive chitosan-based hydrogel containing ferulic acid for treating peripheral arterial disease

Peripheral arterial disease (PAD) affects more than 200 million people worldwide. Recent studies suggest that oxidative stress-related inflammation can lead to the initiation and progression of PAD. Ferulic acid (FA) is a natural phenolic compound and has been proven to have antioxidant and angiogenesis effects. In this study, thermosensitive chitosan-gelatin-based hydrogel was used as a delivery vehicle of FA. The effects of hydrogel encapsulating FA (FA-gel) have been demonstrated in vitro and in vivo. The results revealed that the developed hydrogel with porous structure could provide a sustained release of FA. Post-treatment of FA-gel effectively decreased the oxidative stress-induced damage in human umbilical vein endothelial cells via decreasing endogenous reactive oxygen species production, inflammation-related gene expression and apoptosis level. In the mouse hindlimb ischemia model, the results revealed that FA-gel could improve blood flow, muscle regeneration and decreases inflammation in veins. These results suggested that FA-gel may have a therapeutic potential in PAD.

Early Moderate Intensity Aerobic Exercise Intervention Prevents Doxorubicin-Caused Cardiac Dysfunction Through Inhibition of Cardiac Fibrosis and Inflammation

Doxorubicin (DOX) is known as an effective drug in the fight against various cancers. However, one of the greatest impediments is DOX-induced cardiomyopathy, which may potentially lead to heart failure. Accumulating evidence has shed light on the pathological mechanism of DOX-induced cardiotoxicity, but treatments to mitigate the cardiac damage are still required. In an attempt to address this issue, we evaluated whether exercise provides cardioprotective effects on the DOX-induced cardiotoxicity. We showed that treadmill exercise (3 times/week; 1-week of exercise acclimatization and 4-weeks of endurance exercise) during the DOX treatment successfully prevented the cardiac dysfunction. The DOX-stimulated expression of IκBα, NF-κB, COX-2, and IL-8 were all downregulated by exercise as well as the fibrosis factors (TGF-β1, phosphorylated ERK, Sp1, and CTGF). Moreover, we showed that treadmill exercise diminished the expression of several cardiac remodeling-associated factors, such as FGF2, uPA, MMP2, and MMP9. These results were in line with the finding that exercise intervention reduced cardiac fibrosis and restored cardiac function, with higher values of ejection fraction and fractional shortening compared to the DOX-treated group. Two commonly used indicators of cardiac injury, lactate dehydrogenase, and creatine kinase-MB, were also decreased in the exercise group. Collectively, our results suggested that it may be beneficial to prescribe treadmill exercise as an adjunct therapy to limit cardiac damage caused by DOX.

IL-20 promotes hypoxia/reoxygenation-induced mitochondrial dysfunction and apoptosis in cardiomyocytes by upregulating oxidative stress by activating the PKC/NADPH oxidase pathway

Acute myocardial infarction (AMI) is the maximum critical cardiovascular event and causes high morbidity and mortality worldwide. The ischemia and reperfusion that occur in AMI cause apoptosis and cellular dysfunction in cardiomyocytes. IL-20, an IL-10 family member, is involved in various inflammatory diseases. Therefore, we sought to elucidate the role of IL-20 in the infarcted heart following ischemia/reperfusion (I/R) injury. We found that IL-20 and its receptors, IL-20R1 and IL-20R2, were increased in H2C2 cardiomyoblast cells and ventricular tissues subjected to hypoxia/reoxygenation (H/R) stimulation. The presence of IL-20 further inhibited the cell viability of H9C2 cells and primary cardiomyocytes. Our results suggested that IL-20 elicited an increase in Ca²⁺ and activation of the PKC/NADPH oxidase pathway, leading to the elevation of oxidase stress and downregulation of AKT. Furthermore, we demonstrated that IL-20 was able to mediate H/R-induced apoptosis via PKC/NADPH oxidase/AKT signaling. Our findings implied that IL-20 was responsive to H/R stress in vitro and in rat hearts undergoing I/R injury, and this upregulation of IL-20 may contribute to the apoptosis of cardiomyocytes.

Plate-on-plate technique for treating peri-implant fractures of distal femoral locking plate: a retrospective study of 11 patients

INTRODUCTION

In this study, we aimed to ascertain the feasibility and reliability of the plate-on-plate technique for peri-implant fractures of the distal femoral locking plate when the distal femoral fracture is still unhealed.

MATERIALS AND METHODS

From January 2007 to December 2016, we enrolled 11 patients who received treatment at our institution. All patients underwent at least 1 year of follow-up. Their medical records, imaging studies, visual analogue scores, walking ability, complications, and functional outcomes at 1 year postoperative based on the Short Form (36) Health Survey (SF-36) scores were retrospectively evaluated.

RESULTS

The average follow-up duration was 20.5 (range 15-30) months. All fractures united with satisfactory alignment, and the average time for union was 27.5 (range 16-40) weeks. The average SF-36 scores at 1 year postoperative was 79.2 (range 72-90). Regarding ambulatory status, all patients could perform unrestricted outdoor ambulation.

CONCLUSION

In our case series, the plate-on-plate technique achieved a good bone union rate and functional outcomes with low complication rates and thus may be a good alternative for managing this difficult type of fracture.

Galectin-3 aggravates ox-LDL-induced endothelial dysfunction through LOX-1 mediated signaling pathway

Galectin-3, a biomarker linking oxidative stress and inflammation, participates in different mechanisms related to atherothrombosis, such as inflammation, proliferation, or macrophage chemotaxis. Accumulating evidence indicates that galectin-3 may also promote atherogenesis through inducing endothelial dysfunction. Lectin-like oxidized low-density lipoprotein (oxLDL) receptor-1 (LOX-1), a receptor for oxLDL uptake, contributes to oxLDL-induced endothelial dysfunction. Whether galectin-3 induces endothelial dysfunction through modulation of LOX-1-mediated signaling remains unclear. In the present study, we explored the mechanisms underlying galectin-3 enhanced cytotoxicity of oxLDL in human umbilical vein endothelial cells (HUVECs) and the role of LOX-1. Incubation of HUVECs with galectin-3 increased the expression of LOX-1 in RNA and protein levels. In addition, the expression of LOX-1 induced by oxLDL was promoted by galectin-3. However, pretreatment of LOX-1 antibody reduced LOX-1 mRNA expression level in cells with oxLDL plus galectin-3 incubation. Compared to cells treated with oxLDL alone, reactive oxygen species (ROS) generation via nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation and subsequent activation of p38 mitogen-activated protein kinases followed by nuclear factor kappa B (NF-κB) activation and related inflammatory responses including adhesion molecule expression, adhesiveness of monocytic cells, and IL-8 release were also aggravated in cells treated with galectin-3 combined with oxLDL. Compared to cells treated with galectin-3 plus oxLDL group. We found that LOX-1 antibody mitigated NADPH oxidase activity, p-38 up-regulation, NF-κB activation, and proinflammatory responses in cells treated with galectin-3 combined with oxLDL. We conclude that galectin-3 enhances endothelial LOX-1 expression and propose a new mechanism by which galectin-3 may promote endothelial dysfunction by inducing inflammation via LOX-1/ROS/p38/NF-κB-mediated signaling pathway.

Fucoxanthin Protects against oxLDL-Induced Endothelial Damage via Activating the AMPK-Akt-CREB-PGC1α Pathway

SCOPE

Atherosclerotic cardiovascular disease is the most prevalent cause of mortality and morbidity. Fucoxanthin (FX) possesses anti-hypertensive and anti-obesity properties. However, the molecular mechanisms underlying the inhibitory effects of FX on oxidized low-density lipoprotein (oxLDL)-induced oxidative injuries in human endothelial cells are still largely unknown. This study aims to test the hypothesis that FX protects against oxLDL-induced oxidative stress by upregulating AMP-activated protein kinase (AMPK) and to explore the roles of cAMP response element binding protein (CREB) and peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α).

METHODS AND RESULTS

Human umbilical vein endothelial cells are treated with oxLDL in the presence or absence of FX. FX significantly increases AMPK phosphorylation. In addition, FX diminishes oxLDL-mediated nicotinamide adenine dinucleotide phosphate oxidase activation by inhibiting protein kinase C and subsequently inducing reactive oxygen species generation and impairing the activity of the endogenous antioxidant enzyme superoxidase dismutase. Furthermore, FX restores oxLDL-mediated dephosphorylation of phosphoinositide-3-kinase/Akt and decreases CREB and PGC-1α expression to nearly normal levels. Moreover, FX ameliorates the oxLDL-mediated suppression of mitochondrial function and apoptosis.

CONCLUSION

These findings provide new insights into the possible molecular mechanisms by which FX mitigates oxLDL-induced endothelial oxidative stress and mitochondrial dysfunction.

Neural Mobilization Attenuates Mechanical Allodynia and Decreases Proinflammatory Cytokine Concentrations in Rats With Painful Diabetic Neuropathy

BACKGROUND

Painful diabetic neuropathy (PDN) is a common complication in patients with diabetes. It is related to ischemic nerve damage and the increase in the levels of proinflammatory mediators, such as tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β). Neural mobilization may have the potential to alleviate PDN, but it has not yet been tested. Also, the physiological mechanism of neural mobilization is unclear.

OBJECTIVE

The objective of this study was to investigate treatment effect and physiological mechanism of neural mobilization.

DESIGN

This was an experimental study using rats with streptozocin (or streptozotocin)-induced type 1 diabetes.

METHODS

Three groups were used in the study, the control group (vehicle), the diabetes group (PDN group), and the neural mobilization treatment group (PDN-NM group) (n = 6). Rats in the vehicle group were healthy rats. Rats in the PDN and PDN-NM groups were rats with diabetes. Rats in the PDN-NM group received treatment in the right sciatic nerve, whereas rats in the PDN group did not. Mechanical pain sensitivity and the levels of IL-1β and TNF-α in the sciatic nerve branches and trunk, the L4 to L6 dorsal horn ganglion, and the spinal cord dorsal horn were measured.

RESULTS

Techanical allodynia was alleviated after treatment, but the effect was limited to the treatment side. The concentrations of proinflammatory cytokines were decreased in the nerves that received treatment compared with those on the other side, indicating that neural mobilization may reduce mechanical sensitivity by decreasing the concentrations of local sensitizing agents.

LIMITATIONS

A limitation of this study was that no direct measurement of nerve blood flow was done.

CONCLUSIONS

The results of this study showed that neural mobilization effectively alleviated mechanical allodynia in rats with PDN. The side that received treatment had lower concentrations of TNF-α and IL-1β in the sciatic nerve branches and sciatic nerve trunk; this result may have been related to the alleviation of mechanical allodynia.

Exercise intervention attenuates hyperhomocysteinemia-induced aortic endothelial oxidative injury by regulating SIRT1 through mitigating NADPH oxidase/LOX-1 signaling

Coronary artery disease (CAD) is a critical cardiovascular disease and a cause of high morbidity and mortality in this world. Hyperhomocysteinemia (HHcy) has been suggested as a risk factor for CAD. In addition, SIRT1 (sirtuin 1) has been reported to play a protective role in a variety of diseases, especially in the cardiovascular system. The main purpose of this study was to investigate the effects of exercise training on apoptosis and inflammation in HHcy animals. We also tested whether exercise protected against Hhcy-induced dysfunction of endothelium through modulation of SIRT1. C57BL mice (8 in each group) were fed with or without 1% L-methionine (w/w) in water for 4 months to induce HHcy. We found that Hhcy repressed SIRT1 and AMPK expression and increased NADPH oxidase activity. Plasma MDA, endothelium LOX-1 and p-p38 were up-regulated by Hhcy induction. NF-κB and it downstream molecules were activated under Hhcy situation, thereby promoting pro-inflammatory responses. Moreover, we also reported that Hhcy caused endothelium apoptosis involving Akt inhibition and mitochondria-dependent apoptotic pathways. Exercise training significantly protected against endothelium from Hhcy caused oxidative injuries. In addition, EX527 (SIRT1 inhibitor) reduced the therapeutic effects by exercise. Our results had indicated that exercise training prevent the development of atherosclerosis through SIRT1 activation and oxidative stress inhibition under Hhcy situation.

Chicoric acid is a potent anti-atherosclerotic ingredient by anti-oxidant action and anti-inflammation capacity

Atherosclerotic cardiovascular disease is linked to both oxidative stress and endothelial cell dysfunction. Chicoric acid has antioxidant and anti-inflammatory properties. In the present investigation, we demonstrated that chicoric acid inhibits oxidized low-density lipoprotein (oxLDL)-facilitated dysfunction in human umbilical vein endothelial cells (HUVECs). Oxidative injuries were tested by investigating the formation of intracellular reactive oxygen species (ROS) and by examining the activity of antioxidant enzymes and the function of endothelial nitric oxide synthase (eNOS). We also confirmed that chicoric acid mitigates apoptotic features caused by oxLDL, such as the subsequent break down of mitochondrial transmembrane potential and the activation of Bax, which promote DNA strand breaks and activate caspase-3. Moreover, our data revealed that chicoric acid attenuated the oxLDL activation of NF-κB, the attachment of THP-1 cells and the overexpression of adhesion molecules in human endothelial cells. The results of this study suggest a potential molecular mechanism through which chicoric acid inhibits oxLDL-induced human endothelial dysfunction.

Musashi-1 promotes chemoresistant granule formation by PKR/eIF2α signalling cascade in refractory glioblastoma

Musashi-1 (MSI1), one of the RNA-binding proteins, is abundantly found not only in neural stem cells but also in several cancer tissues and has been reported to act as a positive regulator of cancer progression. Growing evidence indicates that PKR and eIF2α play pivotal roles in the stimulation of stress granule formation as well as in the subsequent translation modulation in response to stressful conditions; however, little is known about whether MSI1 is involved in this PKR/eIF2α cancer stem cell-enhancing machinery. In this study, we demonstrated that MSI1 promotes human glioblastoma multiforme (GBM) stem cells and enhances chemoresistance when exposed to sublethal stress. The overexpression of MSI1 leads to a protective effect in mitigating drug-induced cell death, thus facilitating the formation of chemoresistant stress granules (SGs) in response to arsenic trioxide (ATO) treatment. SG components, such as PKR and eIF2α, were dominantly activated and assembled, while ATO was engaged. The activated PKR and eIF2α contribute to the downstream enhancement of stem cell genes, thereby promoting the progression of GBM. The silencing of MSI1 or PKR both obviously withdrew the phenomena. Taken together, our findings indicate that MSI1 plays a leading role in stress granule formation that grants cancer stem cell properties and chemoresistant stress granules in GBM, in response to stressful conditions via the PKR/eIF2α signalling cascade.

Homocysteine causes dysfunction of chondrocytes and oxidative stress through repression of SIRT1/AMPK pathway: A possible link between hyperhomocysteinemia and osteoarthritis

Emerging evidence has indicated that the perturbed expression of homocysteine (Hcy) may induce mitochondrial dysfunction and disturb bone metabolism. Sirtuin 1 (SIRT1) and AMP-activated protein kinase (AMPK) are two critical sensors that regulate mitochondrial biogenesis and have been recognized as therapeutic targets in osteoarthritis (OA). This study was designed to test whether Hcy caused pro-osteoarthritic changes through modulation of SIRT1 and AMPK. Our results showed that administration of Hcy reduced the SIRT1/AMPK/PGC-1α signaling in chondrocytes, leading to mitochondrial dysfunction as a result of increased oxidative stress and apoptosis. Moreover, we demonstrated that the expression of NF-κB, COX-2, IL-8, and MMP-13 were elevated subsequent to inhibition of SIRT1/AMPK/PGC-1α/PPAR-γ pathway by homocysteine, thereby causing detrimental effects on chondrocytes. In the animal model of diet-induced hyperhomocysteinemia (HHcy), we observed the similar findings that SIRT1/PGC-1α/PPAR-γ cascades were downregulated with elevated MMP-13 and COX-2. Taken together, data from the current study revealed that the reduced SIRT1 by Hcy may contribute to degradative cartilage process, which provided insight into the etiology of OA.

Baicalein is an available anti-atherosclerotic compound through modulation of nitric oxide-related mechanism under oxLDL exposure

OxLDL facilitate reactive oxygen species (ROS) formation and up-regulation of the executioner caspase-3 via the mitochondrial apoptotic pathway involves several critical steps in human endothelial cells. Previous studies reported that oxLDL-facilitated endothelial oxidative stress is associated with impairment of eNOS and up-regulation of inducible nitric oxide synthase (iNOS). Baicalein is the most abundant component that has anti-HIV, anti-tumor, anti-oxidant and free radical scavenging functions. In this present study, we shown that baicalein hinibits oxLDL-caused endothelial dysfunction through suppression of endothelial inflammation and oxidative stress that causes to cellular apoptosis. Specifically, baicalein reduces the elevation of ROS concentration, which subsequently inhibits the oxLDL-decreased expression of anti-oxidant enzymes, enriches the bioavailability of NO, stabilizes the mitochondrial membrane, thereby inhibiting the discharge of cytochrome c from mitochondria, a molecule required for the activation of the pro-apoptotic protein caspase 3. However, inhibition of eNOS impairs the anti-apoptotic and anti-inflammatory effects of baicalein. These results provide new insight into the possible molecular mechanisms by which baicalein protects against atherogenesis by NO-related pathways.

The potential role of epigenetic modulations in BPPV maneuver exercises

Benign paroxysmal positional vertigo (BPPV) is one of the most common complaints encountered in clinics and is strongly correlated with advanced age or, possibly, degeneration. Redistribution exercises are the most effective approaches to treat BPPV, and canalith repositioning procedure (CRP) cure most BPPV cases. However, the mechanisms through which the treatment modulates systemic molecules in BPPV patients remain largely unknown. In this study, we report that the miR-34a and Sirtuin 1 (SIRT1) genes correlated with the treatment effects of CRP in BPPV subjects. We found that miR-34a expression was largely inhibited and SIRT1 expression was significantly reversed after BPPV maneuver treatment. We also confirmed that the PPAR-γ, PGC-1 and FoxO gene expressions were decreased immediately after canalith repositioning procedure (CRP) for BPPV, and were largely increased after a complete cure of BPPV. Moreover, we observed that after a complete recovery of BPPV, the ROS concentrations, pro-inflammatory cytokine concentrations and p53 expression levels were attenuated. We conclude that BPPV treatment might involve some epigenetic regulations through the mediation of miR-34a, SIRT1 functions and repression of redox status.

Masquelet technique with external locking plate for recalcitrant distal tibial nonunion

OBJECTIVE

In the present retrospective study, we aimed to analyze the results of treatment for recalcitrant distal tibial nonunion using Masquelet technique with locking plate as a definitive external fixator.

MATERIALS

We included 15 consecutive cases of distal tibial nonunion treated at our hospital between January 2012 and December 2015. The reconstructive procedure comprised debridement of the nonunion site, deformity correction, stabilization with an external locked plate, defect filling with cement spacer for inducing membrane formation, and bone reconstruction using a cancellous bone autograft (Masquelet technique). All patients were followed-up for at least one year.

RESULTS

Fracture union occurred in all cases after a median of 6.5 months (range, 5-12 months). Mean ankle motion ranged from 12.3 (range, 5-20) degrees of dorsiflexion to 35 (range, 5-55) degrees of plantar flexion. At the final follow-up, the median Iowa ankle score was 83 (range, 68-91). Eight patients had excellent scores, six had good scores, and one had fail score.

CONCLUSION

Although the current study involved only a small number of patients and the intervention comprised two stages, we consider that the used protocol is a simple and valuable alternative for the treatment of recalcitrant distal tibial nonunion.

Metformin regulates oxLDL-facilitated endothelial dysfunction by modulation of SIRT1 through repressing LOX-1-modulated oxidative signaling

It is suggested that oxLDL is decisive in the initiation and development of atherosclerotic injuries. The up-regulation of oxidative stress and the generation of ROS act as key modulators in developing pro-atherosclerotic and anti-atherosclerotic processes in the human endothelial wall. In this present study, we confirmed that metformin enhanced SIRT1 and AMPK expression in human umbilical vein endothelial cells (HUVECs). Metformin also inhibited oxLDL-increased LOX-1 expression and oxLDL-collapsed AKT/eNOS levels. However, silencing SIRT1 and AMPK diminished the protective function of metformin against oxidative injuries. These results provide a new insight regarding the possible molecular mechanisms of metformin.

SIRT1 inhibition causes oxidative stress and inflammation in patients with coronary artery disease

Coronary artery disease (CAD) is the primary critical cardiovascular event. Endothelial cell and monocyte dysfunction with subsequent extravagant inflammation are the main causes of vessel damage in CAD. Thus, strategies that repress cell death and manage unsuitable pro-inflammatory responses in CAD are potential therapeutic strategies for improving the clinical prognosis of patients with CAD. SIRT1 (Sirtuin 1) plays an important role in regulating cellular physiological processes. SIRT1 is also thought to protect the cardiovascular system by means of its antioxidant, anti-inflammation and anti-apoptosis activities. In the present study, we found that the SIRT1 expression levels were repressed and the acetylated p53 expression levels were enhanced in the monocytes of patients with CAD. LOX-1/oxidative stress was also up-regulated in the monocytes of patients with CAD, thereby increasing pro-apoptotic events and pro-inflammatory responses. We also demonstrated that monocytes from CAD patients caused endothelial adhesion molecule activation and the adherence of monocytes and endothelial cells. Our findings may explain why CAD patients remain at an increased risk of long-term recurrent ischemic events and provide new knowledge regarding the management of clinical CAD patients.

PKR activation causes inflammation and MMP-13 secretion in human degenerated articular chondrocytes

Osteoarthritis (OA) is a degenerative joint disease affecting a large population of people. Although the elevated expression of PKR (double stranded RNA-dependent protein kinase) and MMP-13 (collagenase-3) have been indicated to play pivotal roles in the pathogenesis of OA, the exact mechanism underlying the regulation of MMP-13 by PKR following inflammatory stimulation was relatively unknown. The purpose of this study was to determine the signaling pathway involved in the PKR-mediated induction of MMP-13 after TNF-α-stimulation. In this study, cartilages of knee joint were obtained from OA subjects who underwent arthroplastic knee surgery. Cartilages were used for tissue analysis or for chondrocytes isolation. In results, the upregulated expression of PKR was observed in damaged OA cartilages as well as in TNF-α-stimulated chondrocytes. Phosphorylation of PKC (protein kinase C) was found after TNF-α administration or PKR activation using poly(I:C), indicating PKC was regulated by PKR. The subsequent increased activity of NADPH oxidase led to oxidative stress accumulation and antioxidant capacity downregulation followed by an exaggerated inflammatory response with elevated levels of COX-2 and IL-8 via ERK/NF-κB pathway. Activated ERK pathway also impeded the inhibition of MMP-13 by PPAR-γ. These findings demonstrated that TNF-α-induced PKR activation triggered oxidative stress-mediated inflammation and MMP-13 in human chondrocytes. Unraveling these deregulated signaling cascades will deepen our knowledge of OA pathophysiology and provide aid in the development of novel therapies.

Effects of thermosensitive chitosan-gelatin based hydrogel containing glutathione on Cisd2-deficient chondrocytes under oxidative stress

Aging is considered as a primary risk factor in the development of osteoarthritis (OA) which associated with mitochondrial dysfunction and oxidative stress. CDGSH iron sulfur domain 2 (Cisd2) deficiency causes mitochondrial dysfunction and drive premature aging. In the present study, thermosensitive chitosan-gelatin based hydrogel containing glutathione was developed as injectable drug delivery system for administration by minimal invasive surgery for the treatment of OA. Cisd2 deficiency (Cisd2^-/-) mouse induced pluripotent stem cells-derived chondrocytes were established and characterized. The results suggested that 100μM of glutathione may be an optimal concentration to treat Cisd2^-/- chondrocytes without cytotoxicity. The developed hydrogel showed sustained release profile of the glutathione and could decrease the reactive oxygen species level. Post-treatment of glutathione-loaded hydrogel could rescue Cisd2^-/- chondrocytes from oxidative damage via increasing catalase activity, down-regulation of inflammation, and decreasing apoptosis. These results suggest that thermosensitive glutathione-loaded hydrogel may be a potential antioxidant therapeutic strategy for treating Cisd2^-/- chondrocytes in the near future.

Incline treadmill exercise suppresses pain hypersensitivity associated with the modulation of pro-inflammatory cytokines and anti-inflammatory cytokine in rats with peripheral nerve injury

We aimed to investigate the impact of 3 weeks of incline treadmill exercise (TE) on withdrawal responses elicited by thermal and mechanical stimuli, and on anti-inflammatory cytokine (interleukin-10, IL-10) and pro-inflammatory cytokines (IL-6 and tumor necrosis factor-alpha [TNF-α]) expression in the sciatic nerve of rats underwent chronic constriction injury (CCI). Group 1 received a sham-operation where the sciatic nerve was exposed but not ligated, while Group 2 underwent a sham-operation followed by exercising on an 8%-incline treadmill (TE8). Group 3 underwent only the CCI procedure, and Groups 4 and 5 underwent the CCI procedure followed by exercising on an 0%-incline treadmill (TE0) and TE8, respectively. Mechanical and thermal sensitivity and protein expression of IL-10, IL-6 and TNF-α were evaluated on postoperative days 12 and 26. Among the five groups, Group 5 displayed the least weight gain. Compared with Group 3, Group 5 had smaller decreases in mechanical withdrawal thresholds and heat withdrawal latencies. The CCI rats who received TE at 8% incline showed the downregulation of TNF-α and IL-6 in their sciatic nerves on postoperative days 12 and 26, as was found in the Group 3 rats. TE at 8% incline also prevented the downregulation of IL-10 in their sciatic nerves on postoperative day 12. The results demonstrated that increased incline improves the anti-nociceptive effects of treadmill running. Inclined exercise reduces the levels of pro-inflammatory cytokines and increases the level of an anti-inflammatory cytokine.