Advanced oxidation protein products induce apoptosis of human chondrocyte through reactive oxygen species-mediated mitochondrial dysfunction and endoplasmic reticulum stress pathways

Targeted Therapy of Spinal Cord Injury: Inhibition of Apoptosis Is a Promising Therapeutic Strategy

Spinal cord injury (SCI) is a serious disabling central nervous system injury that can lead to motor, sensory, and autonomic dysfunction below the injury level. SCI can be divided into primary injury and secondary injury according to pathological process. Primary injury is mostly irreversible, while secondary injury is a dynamic regulatory process. Apoptosis is an important pathological event of secondary injury and has a significant effect on the recovery of nerve function after SCI. Nerve cell death can further aggravate the microenvironment of the injured site, leading to neurological dysfunction and thus affect the clinical outcome of patients. Therefore, apoptosis plays a crucial role in the pathological progression of secondary SCI, while inhibiting apoptosis may be a promising therapeutic strategy for SCI. This review will summarize and explore the factors that lead to cell death after SCI, the influence of cross talk between signaling pathways and pathways involved in apoptosis and discuss the influence of apoptosis on SCI, and the therapeutic significance of targeting apoptosis on SCI. This review helps us to understand the role of apoptosis in secondary SCI and provides a theoretical basis for the treatment of SCI based on apoptosis.

Esculin suppresses the PERK-eIF2α-CHOP pathway by enhancing SIRT1 expression in oxidative stress-induced rat chondrocytes, mitigating osteoarthritis progression in a rat model

OBJECTIVE

Osteoarthritis (OA) is a degenerative disease characterized by the gradual degeneration of chondrocytes, involving endoplasmic reticulum (ER) stress. Esculin is a natural compound with antioxidant, anti-inflammatory and anti-tumor properties. However, its impact on ER stress in OA therapy has not been thoroughly investigated. We aim to determine the efficiency of Esculin in OA treatment and its underlying mechanism.

METHODS

We utilized the tert-butyl hydroperoxide (TBHP) to establish OA model in chondrocytes. The expression of SIRT1, PERK/eIF2α pathway-related proteins, apoptosis-associated proteins and ER stress-related proteins were detected by Western blot and Real-time PCR. The apoptosis was evaluated by flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining. X-ray imaging, Hematoxylin & Eosin staining, Safranin O staining and immunohistochemistry were used to assess the pharmacological effects of Esculin in the anterior cruciate ligament transection (ACLT) rat OA model.

RESULTS

Esculin downregulated the expression of PERK/eIF2α pathway-related proteins, apoptosis-associated proteins and ER stress-related proteins, while upregulated the expression of SIRT1 and Bcl2 in the TBHP-induced OA model in vitro. It was coincident with the results of TUNEL staining and flow cytometry. We further confirmed the protective effect of Esculin in the rat ACLT-related model.

CONCLUSION

Our results suggest the potential therapeutic value of Esculin on osteoarthritis. It probably inhibits the PERK-eIF2α-ATF4-CHOP pathway by upregulating SIRT1, thereby mitigating endoplasmic reticulum stress and protecting chondrocytes from apoptosis.

Advanced oxidation protein products induce Paneth cells defects by endoplasmic reticulum stress in Crohn's disease

Paneth cells (PC) play a key role in the innate immune response of intestine epithelium, and PC defects contribute to the pathogenesis of Crohn's disease (CD). In this study, we utilized active CD tissues and advanced oxidation protein products (AOPP)-challenged C57BL/6 mouse model to investigate the effect of AOPP on PC defects in CD. We found that AOPP accumulated in active CD tissues and was negatively associated with lysozyme expression, while positively correlated with the presence of ER stress markers. Furthermore, AOPP treatment induced PC defects mainly through excessive ER stress in vivo, and AOPP also caused mitochondria-associated ER membranes formation and mitochondrial dysfunction. In addition, the effects of AOPP could be attenuated by the administration of ER stress inhibitor, TUDCA. These findings suggest a pathogenic role of AOPP contributing to PC defects and may provide the basis for developing new strategies to managing CD.

The role of fibroblast growth factor 7 in cartilage development and diseases

Fibroblast growth factor 7 (FGF7), also known as keratinocyte growth factor (KGF), shows a crucial biological significance in tissue development, wound repair, tumorigenesis, and immune reconstruction. In the skeletal system, FGF7 directs the cellular synaptic extension of individual cells and facilities functional gap junction intercellular communication of a collective of cells. Moreover, it promotes the osteogenic differentiation of stem cells via a cytoplasmic signaling network. For cartilage, reports have indicated the potential role of FGF7 on the regulation of key molecules Cx43 in cartilage and Runx2 in hypertrophic cartilage. However, the molecular mechanism of FGF7 in chondrocyte behaviors and cartilage pathological process remains largely unknown. In this review, we systematically summarize the recent biological function of FGF7 and its regulatory role on chondrocytes and cartilage diseases, especially through the hot focus of two key molecules, Runx2 and Cx43. The current knowledge of FGF7 on the physiological and pathological processes of chondrocytes and cartilage provides us new cues for wound repair of cartilage defect and therapy of cartilage diseases.

Role of reactive oxygen species and mitochondrial damage in rheumatoid arthritis and targeted drugs

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial inflammation, pannus formation, and bone and cartilage damage. It has a high disability rate. The hypoxic microenvironment of RA joints can cause reactive oxygen species (ROS) accumulation and mitochondrial damage, which not only affect the metabolic processes of immune cells and pathological changes in fibroblastic synovial cells but also upregulate the expression of several inflammatory pathways, ultimately promoting inflammation. Additionally, ROS and mitochondrial damage are involved in angiogenesis and bone destruction, thereby accelerating RA progression. In this review, we highlighted the effects of ROS accumulation and mitochondrial damage on inflammatory response, angiogenesis, bone and cartilage damage in RA. Additionally, we summarized therapies that target ROS or mitochondria to relieve RA symptoms and discuss the gaps in research and existing controversies, hoping to provide new ideas for research in this area and insights for targeted drug development in RA.

Endoplasmic reticulum stress mediated by ROS participates in cadmium exposure-induced MC3T3-E1 cell apoptosis

Cadmium (Cd), as one of the seventh most toxic heavy metal pollutants, widely persisted in the environment, leading to osteoblast dysfunction and ultimately Cd-related skeletal disease. However, the damaging effects of Cd on cellular functions and the potential pathogenic mechanisms are still unclear. In our study, Cd is believed to induce mitochondrial dysfunction and endoplasmic reticulum stress (ERS) in a dose-dependent manner, thereby leading to apoptosis, as evident by elevated Drp1, Fis1, GRP78, CHOP, ATF4, P-EIF2α, P-PERK, BAX, cleaved caspase 3 proteins expression and ROS levels, and decreased the levels of Mfn2, OPA1, Bcl2, and intracellular Collagen I, B-ALP, RUNX2, and BGP genes. Additionally, when the exogenous addition of NAC and 4-PBA was added, it was found that NAC and 4-PBA had a positive moderating effect on Cd-induced cell dysfunction. Mechanistically, Cd-induced oxidative stress and apoptosis by upregulating the PERK-EIF2α-ATF4-CHOP signaling pathway and inhibiting the Nrf2/NQO1 pathway. In conclusion, we found that Cd was involved in mitochondrial dysfunction, ERS, and apoptosis in MC3T3-E1 cells, While NAC and 4-PBA relieved ERS and attenuated cell apoptosis.

Mitophagy—A New Target of Bone Disease

Bone diseases are usually caused by abnormal metabolism and death of cells in bones, including osteoblasts, osteoclasts, osteocytes, chondrocytes, and bone marrow mesenchymal stem cells. Mitochondrial dysfunction, as an important cause of abnormal cell metabolism, is widely involved in the occurrence and progression of multiple bone diseases, including osteoarthritis, intervertebral disc degeneration, osteoporosis, and osteosarcoma. As selective mitochondrial autophagy for damaged or dysfunctional mitochondria, mitophagy is closely related to mitochondrial quality control and homeostasis. Accumulating evidence suggests that mitophagy plays an important regulatory role in bone disease, indicating that regulating the level of mitophagy may be a new strategy for bone-related diseases. Therefore, by reviewing the relevant literature in recent years, this paper reviews the potential mechanism of mitophagy in bone-related diseases, including osteoarthritis, intervertebral disc degeneration, osteoporosis, and osteosarcoma, to provide a theoretical basis for the related research of mitophagy in bone diseases.

Chrysin attenuates estradiol-induced endometrial hyperplasia in rats via enhancing PPARα activity

Endometrial hyperplasia (EH) is a complex condition that commonly affects women after menopause. Since the current available treatments for EH are mainly invasive, there is a need for developing new treatment modalities. Chrysin (Ch) is a dihydroxyflavone with numerous promising therapeutic potentials. In this study, Ch's protective effects on estradiol (E2)-induced EH were studied in rats. Animals were allocated randomly to five groups and were treated for 4 weeks as follows: Group 1, control: received the vehicle; group 2, Ch: received Ch 25 mg/kg; group 3, estradiol (E2): received E2 (3 mg/kg) 3 × weekly subcutaneously and the vehicle. Group 4, E2 + Ch 10 mg/kg and group 5, E2 + Ch 25 mg/kg: Ch was given once daily at 10 mg/kg or 25 mg/kg, respectively. In addition, E2 was administered 3 × weekly (3 mg/kg) in groups 4 and 5. Ch inhibited the E2-induced increase in uterine weights and histopathological changes. Ch lowered the cyclin D1 expression. Ch raised the caspase-3 content and Bax mRNA expression. Furthermore, it corrected the raised Bcl2 mRNA expression due to E2. Ch inhibited MDA accumulation and GSH depletion. It also prevents E2-induced SOD and GPx exhaustion. It also ameliorated the rise in NFκB, TNF-α, and IL-6 expression. These effects were correlated with an enhanced PPARα activity ratio relative to the E2 group. This suggests that Ch attenuates EH in this model by exerting anti-proliferative, anti-oxidant, and anti-inflammatory effects partially through increasing PPARα activity.

Delivery of Chondrocyte-Targeting sh-TTTY15 (Testis-Specific Transcript, Y-Linked 15) Nanoparticles Against LncRNA TTTY15 Improves Osteoarthritis by Regulating Autophagy and Oxidative Stress

Objective: To explore the potential role of hyaluronic acid-modified peptide-lncRNA TTTY15 nanoparticles in joint injury of chondrocytes in OA rats. Methods: Cell proliferation, apoptosis and oxidative stress were tested by CCK8, flow cytometry and biochemical analysis. Histopathology and LC3 expression were analyzed by HE, TUNEL and IF. The expression levels of TTTY15, LC3, p62, c-caspase3, Col2A1, ACAN, ADAMTS-5 and MMP13 were tested by RT–qPCR, western blotting and IHC. Autophagosomes were observed by TEM. Results: Bioinformatics and RT–PCR analyses showed that TTTY15 was highly expressed in OA- and TBHP-stimulated chondrocytes. Ov-TTTY15 aggravated TBHP-induced activity decreases, apoptosis, oxidative stress, ECM degradation and autophagic flux reduction in chondrocytes. HA-coated-p5RHH-sh-TTTY15 nanoparticle intervention enhanced the stability and prolonged TTTY15 silencing in chondrocytes. HA-coated-p5RHH-sh-TTTY15 nanoparticles inhibited TBHP-induced C-28/I2 cell damage and activated autophagy, and the inhibitory effect was greater than that of sh-TTTY15. Conclusion: HA-coated-p5RHH-sh-TTTY15 nanoparticles enhanced the stable silencing of TTTY15 in chondrocytes; promoted cell proliferation; inhibited apoptosis, oxidative stress and ECM degradation; and activated autophagy to improve joint injury in OA rats.

Piceatannol SNEDDS Attenuates Estradiol-Induced Endometrial Hyperplasia in Rats by Modulation of NF-κB and Nrf2/HO-1 Axes

Endometrial hyperplasia (EH) is the most common risk factor for endometrial malignancy in females. The pathogenesis of EH has been directly linked to uterine inflammation, which can result in abnormal cell division and decreased apoptosis. Piceatannol (PIC), a natural polyphenolic stilbene, is known to exert anti-inflammatory, antioxidant and anti-proliferative activities. The aim of the present study was to examine the potential preventive role of PIC in estradiol benzoate (EB)-induced EH in rats. A self-nanoemulsifying drug delivery system (SNEDDS) was prepared to improve the solubility of the PIC. Therefore, thirty female Wistar rats were divided into five groups: (1) control, (2) PIC SNEDDS (10 mg/kg), (3) EB (0.6 mg/kg), (4) EB + PIC SNEDDS (5 mg/kg) and (5) EB + PIC SNEDDS (10 mg/kg). The administration of PIC SNEDDS prevented EB-induced increases in uterine weights and histopathological changes. Additionally, it displayed pro-apoptotic and antioxidant activity in the endometrium. Immunohistochemical staining of uterine sections co-treated with PIC SNEDDS showed significantly decreased expression of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and nuclear transcription factor-kappa B (NF-κB). This anti-inflammatory effect was further confirmed by a significant increase in Nrf2 and heme oxygenase-1 (HO-1) expression. These results indicate that SNEDDS nanoformulation of PIC possesses protective effects against experimentally induced EH.

Role of Mitochondria in Physiology of Chondrocytes and Diseases of Osteoarthritis and Rheumatoid Arthritis

PURPOSE OF REVIEW

Mitochondria are recognized to be one of the most important organelles in chondrocytes for their role in triphosphate (ATP) generation through aerobic phosphorylation. Mitochondria also participate in many intracellular processes involving modulating reactive oxygen species (ROS), responding to instantaneous hypoxia stress, regulating cytoplasmic transport of calcium ion, and directing mitophagy to maintain the homeostasis of individual chondrocytes.

DESIGNS

To summarize the specific role of mitochondria in chondrocytes, we screened related papers in PubMed database and the search strategy is ((mitochondria) AND (chondrocyte)) AND (English [Language]). The articles published in the past 5 years were included and 130 papers were studied.

RESULTS

In recent years, the integrity of mitochondrial structure has been regarded as a prerequisite for normal chondrocyte survival and defect in mitochondrial function has been found in cartilage-related diseases, such as osteoarthritis (OA) and rheumatoid arthritis (RA). However, the understanding of mitochondria in cartilage is still largely limited. The mechanism on how the changes in mitochondrial structure and function directly lead to the occurrence and development of cartilage-related diseases remains to be elusive.

CONCLUSION

This review aims to summarize the role of mitochondria in chondrocytes under the physiological and pathological changes from ATP generation, calcium homeostasis, redox regulation, mitophagy modulation, mitochondria biogenesis to immune response activation. The enhanced understanding of molecular mechanisms in mitochondria might offer some new cues for cartilage remodeling and pathological intervention.

Molecular mechanisms underlying the effect of diacerein on trichloroacetic acid-induced hepatic pre-neoplastic lesions in rats

CONCLUSION

IL-1β mediates angiogenesis indirectly, as it has been shown to induce hypoxia-inducible factor-1α (HIF-1α) which upregulates VEGF.

RIP2 knockdown inhibits cartilage degradation and oxidative stress in IL-1β-treated chondrocytes via regulating TRAF3 and inhibiting p38 MAPK pathway

Receptor-interacting protein 2 (RIP2) is a key mediator implicated in multiple cellular processes, and its dysregulation has been recently reported in colitis, asthma and other inflammatory diseases. However, the effects of RIP2 on osteoarthritis (OA) and the underlying mechanisms remain unclear. In this study, we found that RIP2 expression was upregulated in human articular cartilage tissues with OA and interleukin-1β (IL-1β)-treated chondrocytes. Knockdown of RIP2 inhibited IL-1β-induced extracellular matrix (ECM) and oxidative stress. Moreover, knockdown of TRAF3 reversed the effects of RIP2 silencing on cartilage degradation and oxidative stress in IL-1β-induced chondrocytes. In addition, p38 mitogen-activated protein kinase (MAPK) activator dehydrocorydalmine chloride (Dc) also reversed the effects of RIP2 silencing on IL-1β-induced chondrocytes. Taken together, our data reveal that RIP2 knockdown inhibits cartilage degradation and oxidative stress in IL-1β-treated chondrocytes by regulating TRAF3 expression and p38 MAPK pathway activation.

Lycium barbarum polysaccharides in ageing and its potential use for prevention and treatment of osteoarthritis: a systematic review

BACKGROUND

Lycium barbarum polysaccharide (LBP), the most abundant functional component of wolfberry, is considered a potent antioxidant and an anti-ageing substance. This review aims to outline the hallmarks of ageing in the pathogenesis of osteoarthritis (OA), followed by the current understanding of the senolytic effect of LBP and its potential use in the prevention and treatment of OA. This will be discussed through the lens of molecular biology and herbal medicine.

METHODS

A literature search was performed from inception to March 2020 using following keywords: "Lycium barbarum polysaccharide", "DNA damage", antioxidant, anti-apoptosis, anti-inflammation, anti-ageing, osteoarthritis, chondrocytes, fibroblasts, osteoblasts, osteoclasts, and "bone mesenchymal stem cell". The initial search yielded 2287 papers, from which 35 studies were selected for final analysis after screening for topic relevancy by the authors.

RESULTS

In literature different in vitro and in vivo ageing models are used to demonstrate LBP's ability to reduce oxidative stress, restore mitochondrial function, mitigate DNA damage, and prevent cellular senescence. All the evidence hints that LBP theoretically attenuates senescent cell accumulation and suppresses the senescence-associated secretory phenotype as observed by the reduction in pro-inflammatory cytokines, like interleukin-1beta, and matrix-degrading enzymes, such as MMP-1 and MMP-13. However, there remains a lack of evidence on the disease-modifying effect of LBP in OA, although its chondroprotective, osteoprotective and anti-inflammatory effects were reported.

CONCLUSION

Our findings strongly support further investigations into the senolytic effect of LBP in the context of age-related OA.

Advanced glycation end products, advanced oxidation protein products, and ferric reducing ability of plasma in patients with rheumatoid arthritis: a focus on activity scores

BACKGROUND

Rheumatoid arthritis (RA) is a prevalent inflammatory disorder causing functional disabilities. Oxidative stress can cause inflammation and can also be induced by inflammation. Measuring oxidative stress markers could help better understand the pathophysiology of RA and may be used to define the disease severity.

MATERIAL AND METHOD

In this case-control study, 75 RA patients were selected among those referred to the rheumatology clinic. Patients were further categorized into two groups, with active and inactive disease according to the Disease Activity Score (DAS) 28. Forty healthy volunteered persons were selected as the control group. Blood samples were obtained, and advanced glycation end products (AGEs), advanced oxidation protein products (AOPPs), and ferric reducing ability of plasma (FRAP) were measured. The results were compared via student t-test and Chi-square.

RESULTS

Mean ± SD values for AGEs, AOPP, and FRAP in cases and controls were 53.29 ± 6.82 vs. 44.43 ± 7.13 (p = 0.001), 146.08 ± 19.56 vs. 135.79 ± 14.23 (p = 0.004), and 967.13 ± 226.66 vs. 1012.87 ± 215.94 (p = 0.2), respectively. Mean ± SD values for AGEs, AOPP, and FRAP in patients with active disease and inactive disease were 53.32 ± 7.2 vs. 53.26 ± 6.48 (p = 0.9), 146.97 ± 17.56 vs. 145.06 ± 21.84 (p = 0.6), and 953.17 ± 217.09 vs. 983.09 ± 239.31 (p = 0.5), respectively.

CONCLUSION

AGEs and AOPP but not FRAP were significantly increased in RA patients compared to healthy controls. There was no significant difference between AGEs, AOPP, and FRAP in RA patients with active and inactive disease. Key points • AGEs and AOPP but not FRAP were significantly increased in RA patients compared to healthy controls. • There was no significant difference between AGEs, AOPP, and FRAP in RA patients with active and inactive disease.

Spaceflight and hind limb unloading induces an arthritic phenotype in knee articular cartilage and menisci of rodents

Reduced knee weight-bearing from prescription or sedentary lifestyles are associated with cartilage degradation; effects on the meniscus are unclear. Rodents exposed to spaceflight or hind limb unloading (HLU) represent unique opportunities to evaluate this question. This study evaluated arthritic changes in the medial knee compartment that bears the highest loads across the knee after actual and simulated spaceflight, and recovery with subsequent full weight-bearing. Cartilage and meniscal degradation in mice were measured via microCT, histology, and proteomics and/or biochemically after: (1) ~ 35 days on the International Space Station (ISS); (2) 13-days aboard the Space Shuttle Atlantis; or (3) 30 days of HLU, followed by a 49-day weight-bearing readaptation with/without exercise. Cartilage degradation post-ISS and HLU occurred at similar spatial locations, the tibial-femoral cartilage-cartilage contact point, with meniscal volume decline. Cartilage and meniscal glycosaminoglycan content were decreased in unloaded mice, with elevated catabolic enzymes (e.g., matrix metalloproteinases), and elevated oxidative stress and catabolic molecular pathway responses in menisci. After the 13-day Shuttle flight, meniscal degradation was observed. During readaptation, recovery of cartilage volume and thickness occurred with exercise. Reduced weight-bearing from either spaceflight or HLU induced an arthritic phenotype in cartilage and menisci, and exercise promoted recovery.

Activation of autophagy contributes to the protective effects of lycopene against oxidative stress-induced apoptosis in rat chondrocytes

Oxidative stress is commonly associated with osteoarthritis (OA). Lycopene (LYC), a natural carotenoid compound, is an effective antioxidant with potential cartilage-protecting actions. However, how it affects hydrogen peroxide (H₂ O₂ )-induced damage to the cartilage is unclear. In this study, an in vitro oxidative stress model was developed via treating primary chondrocytes with H₂ O₂ . Western blot, immunohistochemistry, and quantitative RT-PCR (qRT-PCR) were used to assess the levels of related factors. Reactive oxygen species (ROS) and apoptosis levels were analyzed by the use of appropriate probes and flow cytometry. The expression and activity of stress-specific enzymes (malondialdehyde, superoxide dismutase, and catalase) were also assessed. The role of autophagy was explored by using the inhibitor, 3-methyladenine (3-MA), as well as monodansylcadaverine staining, western blotting, and red fluorescent protein-green fluorescent protein-light chain 3 lentivirus infection. The result showed LYC exerted significant chondrocyte-protective effects, including reduced inflammation and chondrocyte degradation, increased chondrocyte proliferation, apoptosis inhibition, and reduced ROS production. LYC could effectively induce autophagy in the H₂ O₂ treatment group, and this effect could be attenuated by 3-MA. In terms of mechanism, LYC played a role in inhibiting MAPK and PI3K/Akt/NF-κB axis, which down-regulates levels of mTOR and had a potential therapeutic significance for cartilage degeneration.

Hydrogen sulfide inhibits endoplasmic reticulum stress through the GRP78/mTOR pathway in rat chondrocytes subjected to oxidative stress

The activation of oxidative stress is a primary cause of chondrocyte apoptosis in osteoarthritis (OA). The 78‑kDa glucose‑regulated protein (GRP78)/mammalian target of rapamycin (mTOR) signaling pathway has been demonstrated to be linked with the endoplasmic reticulum (ER) and autophagy. Hydrogen sulfide (H2S) has been reported to exert antioxidant effects. The present study investigated oxidative stress levels via 2',7'‑dichlorofluorescin diacetate and MitoSOX staining, apoptosis rates via flow cytometry and the expression levels of ER stress‑related proteins in GYY4137 (donor of H2S)‑treated chondrocytes (CHs). CHs were isolated from the bilateral hip joints of male rats to examine mitochondrial permeability transition pore opening‑ and mTOR signaling pathway‑related proteins. The results demonstrated that tert‑Butyl hydroperoxide (TBHP) increased CH apoptosis, and treatment with GYY4137 ameliorated TBHP‑mediated the generation of ROS and CH apoptosis. Moreover, TBHP‑treated CHs displayed elevated ER stress sensor expression levels and apoptotic rates; however, the TBHP‑induced protein expression levels were decreased following GYY4137 treatment. In the present study, treatment with either GYY4137 or transfection with GRP78 siRNA both suppressed the activation of p‑P70S6k and p‑mTOR. H2S played an important role in regulating ER stress in TBHP‑stimulated CHs. GYY4137 promoted autophagy, which was accompanied by the inhibition of ER stress. On the whole, the present study demonstrates that TBHP‑induced oxidative stress stimulates ER interactions and CH apoptosis, which are suppressed by exogenous H2S via modulating the GRP78/mTOR signaling pathway.

Role of mitochondria in mediating chondrocyte response to mechanical stimuli

As the most common form of arthritis, osteoarthritis (OA) has become a major cause of severe joint pain, physical disability, and quality of life impairment in the affected population. To date, precise pathogenesis of OA has not been fully clarified, which leads to significant obstacles in developing efficacious treatments such as failures in finding disease-modifying OA drugs (DMOADs) in the last decades. Given that diarthrodial joints primarily display the weight-bearing and movement-supporting function, it is not surprising that mechanical stress represents one of the major risk factors for OA. However, the inner connection between mechanical stress and OA onset/progression has yet to be explored. Mitochondrion, a widespread organelle involved in complex biological regulation processes such as adenosine triphosphate (ATP) synthesis and cellular metabolism, is believed to have a controlling role in the survival and function implement of chondrocytes, the singular cell type within cartilage. Mitochondrial dysfunction has also been observed in osteoarthritic chondrocytes. In this review, we systemically summarize mitochondrial alterations in chondrocytes during OA progression and discuss our recent progress in understanding the potential role of mitochondria in mediating mechanical stress-associated osteoarthritic alterations of chondrocytes. In particular, we propose the potential signaling pathways that may regulate this process, which provide new views and therapeutic targets for the prevention and treatment of mechanical stress-associated OA.

Allicin Attenuated Advanced Oxidation Protein Product-Induced Oxidative Stress and Mitochondrial Apoptosis in Human Nucleus Pulposus Cells

Intervertebral disc degeneration (IDD) is one of the most common chronic degenerative musculoskeletal disorders. Oxidative stress-induced apoptosis of the nucleus pulposus (NP) cells plays a key role during IDD progression. Advanced oxidation protein products (AOPP), novel biomarkers of oxidative stress, have been reported to function in various diseases due to their potential for disrupting the redox balance. The current study is aimed at investigating the function of AOPP in the oxidative stress-induced apoptosis of human NP cells and the alleviative effects of allicin during this process which was known for its antioxidant properties. AOPP were demonstrated to hamper the viability and proliferation of NP cells in a time- and concentration-dependent manner and cause cell apoptosis markedly. High levels of reactive oxygen species (ROS) and lipid peroxidation product malondialdehyde (MDA) were detected in NP cells after AOPP stimulation, which resulted in depolarized mitochondrial transmembrane potential (MTP). Correspondingly, higher levels of AOPP were discovered in the human degenerative intervertebral discs (IVD). It was also found that allicin could protect NP cells against AOPP-mediated oxidative stress and mitochondrial dysfunction via suppressing the p38-MAPK pathway. These results disclosed a significant role of AOPP in the oxidative stress-induced apoptosis of NP cells, which could be involved in the primary pathogenesis of IDD. It was also revealed that allicin could be a promising therapeutic approach against AOPP-mediated oxidative stress during IDD progression.

Activation of dopamine receptor D1 inhibits glioblastoma tumorigenicity by regulating autophagic activity

PURPOSE

Recent studies have reported important roles of dopamine receptors in the early development and progression of glioblastoma (GBM). Here, we tested the antitumor activity of a Dopamine receptor D1 (DRD1) agonist, either alone or in combination with temozolomide (TMZ) on GBM cells.

METHODS

Immunofluorescence, immunohistochemistry and Western blotting were used to detect dopamine receptor expression in primary human GBM tissues. In addition, clinical data of GBM patients downloaded from The Cancer Genome Atlas (TCGA) were analyzed. Image-based tracking analysis of LC3 using a mCherry-eGFP-LC3 plasmid was utilized to monitor autophagic flux. Transmission electron microscopy (TEM) was used to visualize aggregation of autophagosomes/autolysosomes. Finally, DRD1 agonist (SKF83959)-induced inhibition of GBM growth was assessed in vitro and in vivo.

RESULTS

Positive DRD1 expression was observed in human GBM tissues and found to be related with a good clinical outcome. DRD1 activation specifically inhibited GBM cell growth and significantly disrupted autophagic flux, which led to tumor cell death. Moreover, we found that DRD1 agonist treatment inhibited auto-lysosomal degradation in GBM cells and that this process was calcium overload dependent and related to inhibition of mammalian target of rapamycin (mTOR). Finally, we found that DRD1 agonist and TMZ co-treatment yielded a synergistic therapeutic effect both in vivo and in vitro.

CONCLUSIONS

From our data we conclude that DRD1 activation inhibits GBM cell growth and may serve as an alternative avenue for the design of future GBM therapies.

Intake of antioxidant vitamins in women with different physical activity levels

Study aim: The purpose of this study was to compare intake of antioxidant vitamins (A, C, E) in young women with various levels of physical activity.

Material and methods: The study included 3 groups of females: 40 women with no extra physical activity (Sedentary), 40 women involved in regular, moderate sports activities (Recreationally Active) and 40 female athletes competing at an international level (Athletes). Participants’ diet was assessed on the basis of 3-day diet records which were analysed using the computer program ‘Dieta 5.0’. Body composition was evaluated by the bioelectrical impedance analysis (BIA) method.

Results: Athletes were characterized by the lowest body fat and highest lean body mass in comparison with the other groups. They also showed the highest intake of energy, proteins and carbohydrates compared to Active and Sedentary women. The consumption of vitamin A amounted to 180.0% of RDA in Athletes, 98.8% in Recreationally Active and 97.8% in Sedentary women. Vitamin C intake in Athletes equalled 275.0% of RDA, whereas the deficiency of this vitamin was observed in Recreationally Active and Sedentary women (62.3% and 46.1% of RDA, respectively). The study groups showed consumption of vitamin E at the level of 146.7% of AI in Athletes, 115.0% in Recreationally Active and 111.3% in Sedentary women.

Conclusion: Athletes consumed excessive amounts of antioxidant vitamins. Recreationally Active and Sedentary women met the demand for vitamin A and E, but the intake of vitamin C was not sufficient, which could lead to health problems. The current findings also indicate that energy intake was at a low level regardless of the study group.

Aging Fits the Disease Criteria of the International Classification of Diseases

The disease criteria used by the World Health Organization (WHO) were applied to human biological aging in order to assess whether aging can be classified as a disease. These criteria were developed for the 11th revision of the International Classification of Diseases (ICD) and included disease diagnostics, mechanisms, course and outcomes, known interventions, and linkage to genetic and environmental factors. RESULTS: Biological aging can be diagnosed with frailty indices, functional, blood-based biomarkers. A number of major causal mechanisms of human aging involved in various organs have been described, such as inflammation, replicative cellular senescence, immune senescence, proteostasis failures, mitochondrial dysfunctions, fibrotic propensity, hormonal aging, body composition changes, etc. We identified a number of clinically proven interventions, as well as genetic and environmental factors of aging. Therefore, aging fits the ICD-11 criteria and can be considered a disease. Our proposal was submitted to the ICD-11 Joint Task force, and this led to the inclusion of the extension code for "Ageing-related" (XT9T) into the "Causality" section of the ICD-11. This might lead to greater focus on biological aging in global health policy and might provide for more opportunities for the new therapy developers.

Hydroxytyrosol promotes autophagy by regulating SIRT1 against advanced oxidation protein product‑induced NADPH oxidase and inflammatory response

Advanced oxidation protein products (AOPPs) can trigger NADPH oxidase (NOX) and lead to the production of reactive oxygen species (ROS) in the pathophysiology of rheumatoid arthritis (RA). Hydroxytyrosol (HT) is a phenolic composite in olive oil that has antioxidant and anti‑inflammatory effects and enhances autophagy. Early research has revealed that HT can activate the silent information regulator 1 (SIRT1) pathway to induce autophagy and alleviate the cartilage inflammatory response caused by H2O2. However, whether HT can attenuate AOPP‑induced NOX and inflammatory responses remains to be elucidated. The present study aimed to investigate how HT can alleviate the damage caused by AOPPs. In cell experiments, chondrocytes were pre‑stimulated with HT and then exposed to AOPPs. First, it was found that HT promoted autophagy through the SIRT1 pathway, increased the expression of autophagy‑related proteins including microtubule‑associated protein 1 light chain 3, autophagy related (ATG)5 and ATG7, and decreased the expression of P62. Furthermore, HT reduced the expression of NOX, which was affected by AOPPs in chondrocytes through the SIRT1 pathway. Finally, the expression of inflammatory cytokines caused by AOPPs was downregulated following HT treatment. In conclusion, it was found that HT reduced the expression of NOX and inhibited the inflammatory response caused by AOPPs in chondrocytes through the SIRT1 pathway.

Hepatocellular Toxicity of Paris Saponins I, II, VI and VII on Two Kinds of Hepatocytes-HL-7702 and HepaRG Cells, and the Underlying Mechanisms

Rhizoma paridis is a popularly-used Chinese medicine in clinics, based on the pharmacodynamic properties of its saponin components. The four main saponins in Rhizoma paridis are designated saponins I, II, VI, and VII. At present, much attention is focused on the anticancer effect of Rhizoma paridis which is manifested in its cytotoxicity to various cancer cells. The purpose of this study was to investigate the hepatocellular toxicities of the four saponins in Rhizoma paridis and the relative intensities of their cytotoxic effects. It was found that the four saponins were cytotoxic to two types of hepatocytes-HL-7702 and HepaRG cells. The cytotoxicities of the four saponins to the two cell models were compared. One of the most cytotoxic saponins was Rhizoma paridis saponin I (PSI). This was used to determine the mechanism of hepatocellular toxicity. Results from MTT assays demonstrated that the four saponins induced apoptosis of the two hepatocyte models in a dose-dependent and time-dependent manner. In addition, fluorescent 4′,6-diamidino-2-phenylindole (DAPI) staining was used to observe the morphological changes of HepaRG cells after saponin administration. Further, as the concentration increased, PSI-induced lactate dehydrogenase (LDH) release from HepaRG cells increased gradually. In addition, PSI enhanced the levels of reactive oxygen species (ROS) and blocked the S and G2 phases of the cell cycle in HepaRG cells. A western blot indicated that PSI upregulated the protein expression levels of p53, p21, and Fas. Furthermore, the PSI-induced changes in the p53 protein increased the Bax/bcl-2 ratio, resulting in enhancement of the release of mitochondrial cytochrome c, activation of caspases-3, -8, and -9, poly-ADP ribose polymerase (PARP), and ultimately apoptosis. Increased Fas protein activated caspase-8, which led to the activation of caspase-3 and its downstream PARP protein, resulting in cell apoptosis. These results indicate that PSI induced apoptosis in HepaRG cells through activation of ROS and death receptor pathways. The results obtained in this study suggest that the hepatocellular toxicity of saponins in Rhizoma paridis should be considered during the clinical application of this drug. In addition, they provide a reference for future anti-cancer studies on Rhizoma paridis.

Evaluation of five additives to mitigate toxicity of cryoprotective agents on porcine chondrocytes

Cryoprotective agents (CPAs) are used in cryopreservation protocols to achieve vitrification. However, the high CPA concentrations required to vitrify a tissue such as articular cartilage are a major drawback due to their cellular toxicity. Oxidation is one factor related to CPA toxicity to cells and tissues. Addition of antioxidants has proven to be beneficial to cell survival and cellular functions after cryopreservation. Investigation of additives for mitigating cellular CPA toxicity will aid in developing successful cryopreservation protocols. The current work shows that antioxidant additives can reduce the toxic effect of CPAs on porcine chondrocytes. Our findings showed that chondroitin sulphate, glucosamine, 2,3,5,6-tetramethylpyrazine and ascorbic acid improved chondrocyte cell survival after exposure to high concentrations of CPAs according to a live-dead cell viability assay. In addition, similar results were seen when additives were added during CPA removal and articular cartilage sample incubation post CPA exposure. Furthermore, we found that incubation of articular cartilage in the presence of additives for 2 days improved chondrocyte recovery compared with those incubated for 4 days. The current results indicated that the inclusion of antioxidant additives during exposure to high concentrations of CPAs is beneficial to chondrocyte survival and recovery in porcine articular cartilage and provided knowledge to improve vitrification protocols for tissue banking of articular cartilage.

Curcumin Inhibits the PERK-eIF2α-CHOP Pathway through Promoting SIRT1 Expression in Oxidative Stress-induced Rat Chondrocytes and Ameliorates Osteoarthritis Progression in a Rat Model

Oxidative stress plays a crucial role in the occurrence and development of osteoarthritis (OA) through the activation of endoplasmic reticulum (ER) stress. Curcumin is a polyphenolic compound with significant antioxidant and anti-inflammatory activity among various diseases. To elucidate the role of curcumin in oxidative stress-induced chondrocyte apoptosis, this study investigated the effect of curcumin on ER stress-related apoptosis and its potential mechanism in oxidative stress-induced rat chondrocytes. The results of flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining showed that curcumin can significantly attenuate ER stress-associated apoptosis. Curcumin inhibited the expression of cleaved caspase3, cleaved poly (ADP-ribose) polymerase (PARP), C/EBP homologous protein (CHOP), and glucose-regulated protein78 (GRP78) and upregulated the chondroprotective protein Bcl2 in TBHP-treated chondrocytes. In addition, curcumin promoted the expression of silent information regulator factor 2-related enzyme 1 (SIRT1) and suppressed the expression of activating transcription factor 4 (ATF4), the ratio of p-PERK/PERK, p-eIF2α/eIF2α. Our anterior cruciate ligament transection (ACLT) rat OA model research demonstrated that curcumin (50 mg/kg and 150 mg/kg) ameliorated the degeneration of articular cartilage and inhibited chondrocyte apoptosis in ACLT rats in a dose-dependent manner. By applying immunohistochemical analysis, we found that curcumin enhanced the expression of SIRT1 and inhibited the expression of CHOP and cleaved caspase3 in ACLT rats. Taken together, our present findings firstly indicate that curcumin could inhibit the PERK-eIF2α-CHOP axis of the ER stress response through the activation of SIRT1 in tert-Butyl hydroperoxide- (TBHP-) treated rat chondrocytes and ameliorated osteoarthritis development in vivo.

Quercetin attenuates oxidative stress-induced apoptosis via SIRT1/AMPK-mediated inhibition of ER stress in rat chondrocytes and prevents the progression of osteoarthritis in a rat model

Apoptosis of chondrocytes are the main initiator of osteoarthritis (OA) and can be explained by oxidative stress and endoplasmic reticulum (ER) stress, thus the pharmacological interventions aimed at inhibiting of these pathways may be a promising approach for the management of OA. Quercetin is a member of the flavonoid family and has antioxidant and anti-inflammatory properties in degenerative diseases. However, its effects and potential mechanisms on the pathological process of OA are not very clear. The present study aimed to investigate the protective effects of quercetin on OA and the underlying mechanisms. The tert-butyl hydroperoxide (TBHP)-stimulated rat chondrocytes and destabilization of the medial meniscus OA rat model was used to explore the protective effects of quercetin. Our results showed that quercetin treatment can attenuate oxidative stress, ER stress, and associated apoptosis. Moreover, quercetin inhibited ER stress through activating the sirtuin1/adenosine monophosphate-activated protein kinase (SIRT1/AMPK) signaling pathway. The protective effects of quercetin were also observed in OA rat model which is evidenced by abolished cartilage degeneration and decreased chondrocytes apoptosis in the knee joints. Our results suggested that quercetin is a promising treatment for OA.

Advanced oxidation protein products induce pre-osteoblast apoptosis through a nicotinamide adenine dinucleotide phosphate oxidase-dependent, mitogen-activated protein kinases-mediated intrinsic apoptosis pathway

Osteoblast apoptosis contributes to age‐related bone loss. Advanced oxidation protein products (AOPPs) are recognized as the markers of oxidative stress and potent inducers of apoptosis. We have demonstrated that AOPP accumulation was correlated with age‐related bone loss. However, the effect of AOPPs on the osteoblast apoptosis still remains unknown. Exposure of osteoblastic MC3T3‐E1 cells to AOPPs caused the excessive generation of reactive oxygen species (ROS) by activating nicotinamide adenine dinucleotide phosphate (NADPH) oxidases. Increased ROS induced phosphorylation of mitogen‐activated protein kinases (MAPKs), which subsequently triggered intrinsic apoptosis pathway by inducing mitochondrial dysfunction, endoplasmic reticulum stress, and Ca²⁺ overload and eventually leads to apoptosis. Chronic AOPP loading in aged Sprague‐Dawley rats induced osteoblast apoptosis and activated NADPH oxidase signaling cascade, in combination with accelerated bone loss and deteriorated bone microstructure. Our study suggests that AOPPs induce osteoblast apoptosis by the NADPH oxidase‐dependent, MAPK‐mediated intrinsic apoptosis pathway.

Role of PPAR-α agonist fenofibrate in the treatment of induced benign prostatic hyperplasia with dysplastic changes in rats

Nearly all men who reach average life expectancy have prostate disease. The most common is benign prostatic hyperplasia (BPH). Peroxisome proliferator-activated receptor alpha (PPARα) had protective effect in different models, but still, there are no studies explain its role in BPH. So that we investigated the effect of fenofibrate (FEN) on induced BPH by testosterone propionate (TP) (3 mg/kg/day for 4 weeks) subcutaneous injection followed by FEN (300 mg/kg/day) was given orally for 4 weeks. We measured prostate weights changes, prostatic tissue superoxide dismutase (SOD), and malondialdehyde (MDA) levels. Prostate-specific antigen (PSA), dihydrotestosterone (DHT), and total antioxidant capacity (TAC) in serum were determined. The mRNA gene expressions of proliferating cell nuclear antigen (PCNA), PPARα, and glutathione peroxidase (GPx) in prostatic tissue were also measured by quantitative real-time polymerase chain reaction. In addition, the histopathological changes and activated caspase3 immunoexpression were evaluated. Our results showed that TP succeeded in induction of BPH, which was detected by significant increase in prostate weights, prostatic tissue MDA, serum levels of DHT, PSA, and mRNA gene expression of PCNA but significant decrease in PPARα and GPx gene expression. Moreover, TAC in serum and SOD level in prostate tissue decreased. The histopathological examination showed typical changes of BPH with dysplastic changes with marked decrease in activated caspase3 immunoexpression indicating marked suppression of the apoptotic process. FEN significantly improved all disturbed parameters of BPH model. Moreover, there are no dysplastic changes with co-administration of FEN to BPH induced group.

Comparative study of amlodipine vs. cilnidipine for the prevention of hepatic ischemia-reperfusion injury in rat model

Ca²⁺ signaling plays crucial role in ischemia and reperfusion (I/R) injury. Although blockade of L-type Ca²⁺ channels by amlodipine (AML) has been shown to suppress hepatic I/R injury in several animal models, information is still needed regarding the hepatoprotective effects of the dual L/N-type Ca²⁺ channel blockers, cilnidipine (CIL). We examined the effect of pretreatment with AML or CIL (100 μg/kg i.p.) 45 min before induction of 60 min of liver ischemia followed by reperfusion, on oxidative stress markers, liver enzymes, serum tumor necrosis factor-α, interleukin-1β, apoptosis markers, and nuclear factor KB after 6 and 24 h of hepatic reperfusion. Both drugs significantly ameliorated biochemical and histological markers of hepatic I/R injury, but protection with CIL was more significant at the 6-h time point where protection with AML outlasted that of CIL. Both drugs offered significant protection against hepatic I/R damage, but the protection with CIL seemed more potent but of shorter duration than that observed with AML possibly due to the shorter half-life of CIL.

Trehalose ameliorates oxidative stress-mediated mitochondrial dysfunction and ER stress via selective autophagy stimulation and autophagic flux restoration in osteoarthritis development

Oxidative stress-related apoptosis and autophagy play crucial roles in the development of osteoarthritis (OA), a progressive cartilage degenerative disease with multifactorial etiologies. Here, we determined autophagic flux changes and apoptosis in human OA and tert-Butyl hydroperoxide (TBHP)-treated chondrocytes. In addition, we explored the potential protective effects of trehalose, a novel Mammalian Target of Rapamycin (mTOR)-independent autophagic inducer, in TBHP-treated mouse chondrocytes and a destabilized medial meniscus (DMM) mouse OA model. We found aberrant p62 accumulation and increased apoptosis in human OA cartilage and chondrocytes. Consistently, p62 and cleaved caspase-3 levels increased in mouse chondrocytes under oxidative stress. Furthermore, trehalose restored oxidative stress-induced autophagic flux disruption and targeted autophagy selectively by activating BCL2 interacting protein 3 (BNIP3) and Phosphoglycerate mutase family member 5 (PGAM5). Trehalose could ameliorate oxidative stress-mediated mitochondrial membrane potential collapse, ATP level decrease, dynamin-related protein 1 (drp-1) translocation into the mitochondria, and the upregulation of proteins involved in mitochondria and endoplasmic reticulum (ER) stress-related apoptosis pathway. In addition, trehalose suppressed the cleavage of caspase 3 and poly(ADP-ribose) polymerase (PARP) and prevented DNA damage under oxidative stress. However, the anti-apoptotic effects of trehalose in TBHP-treated chondrocytes were partially abolished by autophagic flux inhibitor chloroquine and BNIP3- siRNA. The protective effect of trehalose was also found in mouse OA model. Taken together, these results indicate that trehalose has anti-apoptotic effects through the suppression of oxidative stress-induced mitochondrial injury and ER stress which is dependent on the promotion of autophagic flux and the induction of selective autophagy. Thus, trehalose is a promising therapeutic agent for OA.

Insights on Molecular Mechanisms of Chondrocytes Death in Osteoarthritis

Osteoarthritis (OA) is a joint pathology characterized by progressive cartilage degradation. Medical care is mainly based on alleviating pain symptoms. Compelling studies report the presence of empty lacunae and hypocellularity in cartilage with aging and OA progression, suggesting that chondrocyte cell death occurs and participates to OA development. However, the relative contribution of apoptosis per se in OA pathogenesis appears complex to evaluate. Indeed, depending on technical approaches, OA stages, cartilage layers, animal models, as well as in vivo or in vitro experiments, the percentage of apoptosis and cell death types can vary. Apoptosis, chondroptosis, necrosis, and autophagic cell death are described in this review. The question of cell death causality in OA progression is also addressed, as well as the molecular pathways leading to cell death in response to the following inducers: Fas, Interleukin-1β (IL-1β), Tumor Necrosis factor-α (TNF-α), leptin, nitric oxide (NO) donors, and mechanical stresses. Furthermore, the protective role of autophagy in chondrocytes is highlighted, as well as its decline during OA progression, enhancing chondrocyte cell death; the transition being mainly controlled by HIF-1α/HIF-2α imbalance. Finally, we have considered whether interfering in chondrocyte apoptosis or promoting autophagy could constitute therapeutic strategies to impede OA progression.