Effect of S-methylisothiourea, an inducible nitric oxide synthase inhibitor, in joint pain and pathology in surgically induced model of osteoarthritis

Potential therapeutic strategies for osteoarthritis via CRISPR/Cas9 mediated gene editing

Osteoarthritis (OA) is an incapacitating and one of the most common physically degenerative conditions with an assorted etiology and a highly complicated molecular mechanism that to date lacks an efficient treatment. The capacity to design biological networks and accurately modify existing genomic sites holds an apt potential for applications across medical and biotechnological sciences. One of these highly specific genomes editing technologies is the CRISPR/Cas9 mechanism, referred to as the clustered regularly interspaced short palindromic repeats, which is a defense mechanism constituted by CRISPR associated protein 9 (Cas9) directed by small non-coding RNAs (sncRNA) that bind to target DNA through Watson-Crick base pairing rules where subsequent repair of the target DNA is initiated. Up-to-date research has established the effectiveness of the CRISPR/Cas9 mechanism in targeting the genetic and epigenetic alterations in OA by suppressing or deleting gene expressions and eventually distributing distinctive anti-arthritic properties in both in vitro and in vivo osteoarthritic models. This review aims to epitomize the role of this high-throughput and multiplexed gene editing method as an analogous therapeutic strategy that could greatly facilitate the clinical development of OA-related treatments since it's reportedly an easy, minimally invasive technique, and a comparatively less painful method for osteoarthritic patients.

The role of apoptosis in the pathogenesis of osteoarthritis

PURPOSE

Apoptosis is an important physiological process, making a great difference to development and tissue homeostasis. Osteoarthritis (OA) is a chronic joint disease characterized by degeneration and destruction of articular cartilage and bone hyperplasia. This purpose of this study is to provide an updated review of the role of apoptosis in the pathogenesis of osteoarthritis.

METHODS

A comprehensive review of the literature on osteoarthritis and apoptosis was performed, which mainly focused on the regulatory factors and signaling pathways associated with chondrocyte apoptosis in osteoarthritis and other pathogenic mechanisms involved in chondrocyte apoptosis.

RESULTS

Inflammatory mediators such as reactive oxygen species (ROS), nitric oxide (NO), IL-1β, tumor necrosis factor-α (TNF-α), and Fas are closely related to chondrocyte apoptosis. NF-κB signaling pathway, Wnt signaling pathway, and Notch signaling pathway activate proteins and gene targets that promote or inhibit the progression of osteoarthritis disease, including chondrocyte apoptosis and ECM degradation. Long non-coding RNAs (LncRNAs) and microRNAs (microRNAs) have gradually replaced single and localized research methods and become the main research approaches. In addition, the relationship between cellular senescence, autophagy, and apoptosis was also briefly explained.

CONCLUSION

This review offers a better molecular delineation of apoptotic processes that may help in designing new therapeutic options for OA treatment.

Connection between Osteoarthritis and Nitric Oxide: From Pathophysiology to Therapeutic Target

Osteoarthritis (OA), a disabling joint inflammatory disease, is characterized by the progressive destruction of cartilage, subchondral bone remodeling, and chronic synovitis. Due to the prolongation of the human lifespan, OA has become a serious public health problem that deserves wide attention. The development of OA is related to numerous factors. Among the factors, nitric oxide (NO) plays a key role in mediating this process. NO is a small gaseous molecule that is widely distributed in the human body, and its synthesis is dependent on NO synthase (NOS). NO plays an important role in various physiological processes such as the regulation of blood volume and nerve conduction. Notably, NO acts as a double-edged sword in inflammatory diseases. Recent studies have shown that NO and its redox derivatives might be closely related to both normal and pathophysiological joint conditions. They can play vital roles as normal bone cell-conditioning agents for osteoclasts, osteoblasts, and chondrocytes. Moreover, they can also induce cartilage catabolism and cell apoptosis. Based on different conditions, the NO/NOS system can act as an anti-inflammatory or pro-inflammatory agent for OA. This review summarizes the studies related to the effects of NO on all normal and OA joints as well as the possible new treatment strategies targeting the NO/NOS system.

Oral Administration of a Chemically Modified Curcumin, TRB-N0224, Reduced Inflammatory Cytokines and Cartilage Erosion in a Rabbit ACL Transection Injury Model

OBJECTIVE

To evaluate the effects of TRB-N0224, a chemically modified curcumin (CMC) with zinc binding properties and improved pharmacokinetics, in a rabbit anterior cruciate ligament (ACL) transection injury-induced model of osteoarthritis (OA).

DESIGN

Thirty-eight skeletally mature New Zealand white rabbits were studied in 4 groups: a sham with arthrotomy (n = 6), control with ACL transection (n = 6), and 2 treatment groups with ACL transection and administration of TRB-N0224 at low (25 mg/kg/day) (n = 13) and high (50 mg/kg/day) (n = 13) doses. After euthanization at 12 weeks, outcomes were measured by post-necropsy gross morphology, biomechanics, and cartilage and synovium histology. Rabbit blood ELISA quantified cytokine and matrix metalloproteinase (MMP) concentrations at 0, 4, 8, and 12 weeks.

RESULTS

Both treatment doses had fewer distal femoral condyle erosive defects than the control; the low dose demonstrated a mean 78% decrease (P < 0.01). Histologically, the low- and high-dose treatment groups had fewer cartilage pathologic changes and less severe synovitis than the control. CMC alone did not have a major effect on the biomechanics of healthy cartilage or cartilage in the ACL transection model, as demonstrated in 5 of the 6 measured properties/regions (P < 0.05). ELISA results suggested that the key mediators of OA, (interleukin) IL-1β, IL-6, TNFα (tumor necrosis factor-α), MMP-9, and MMP-13, had decreased concentrations with TRB-N0224 treatment at different time points between weeks 4 to 12 (P < 0.05).

CONCLUSIONS

In the pathogenesis of OA, an imbalance exists between catabolic and anabolic mediators. These results suggest the potential of TRB-N0224 to modulate MMP and cytokine levels, slowing the macroscopic and histopathological progression of OA.

Recent advances in nanotherapeutic strategies that target nitric oxide pathway for preventing cartilage degeneration

Nitric oxide (NO) is an important inflammatory mediator involved in the development and progression of osteoarthritis (OA). Increased production of NO in the affected joints promote cartilage damage. As NO synthesis is catalysed by the inducible NO synthase (iNOS) enzyme, iNOS inhibition serves as an attractive therapeutic target to prevent NO release. Despite a number of direct and indirect iNOS inhibitor molecules demonstrating chondro-protective effect, none have reached the clinic. Its limited bioavailability and adverse side effects served as a deterrent for pursuing clinical trials in OA patients. With the advent of nanotechnology, interest in targeting NO for preventing cartilage degeneration has revived. In this article, we discuss the limitations of the existing molecules and provide an insight on recent nanotechnology-based strategies that have been explored for the diagnosis and inhibition of NO in OA. These approaches hold promise in reviving the hitherto under explored potential of targeting NO to address OA.

Aminoguanidine inhibits IL-1β-induced protein expression of iNOS and COX-2 by blocking the NF-κB signaling pathway in rat articular chondrocytes

Osteoarthritis is a chronic joint disease which has a serious impact on the health and quality of life of affected humans and animals. As an inhibitor of inducible nitric oxide synthase (iNOS), aminoguanidine (AG) displays anti-inflammatory effects. The purpose of the present study was to investigate the effect of AG on the expression of iNOS and cyclooxygenase-2 (COX-2), and the activity of the NF-κB signaling pathway in rat chondrocytes stimulated by interleukin-1β (IL-1β). The viability of chondrocytes treated with AG (0.3, 1 or 3 mM) alone was determined using a Cell Counting Kit-8 assay. Subsequently, the chondrocytes were treated with either 10 ng/ml IL-1β alone, or co-treated with increasing concentrations of AG (0.3, 1 or 3 mM) and 10 ng/ml IL-1β. The protein levels of COX-2, iNOS, phosphorylated (p)-p65, p65, p-NF-κβ inhibitor α (IκBα), IκBα, p-inhibitor of NF-κβ-β (IKKβ) and IKKβ were evaluated by western blotting. NF-κB translocation was determined by immunofluorescence analysis. Western blotting and reverse transcription-quantitative PCR were used to detect expression levels of relevant proteins/genes. The results suggested that the inhibitory effect of AG on the protein and gene expression levels of iNOS and COX-2 in IL-1β-treated chondrocytes was dose-dependent. In addition, AG decreased the level of phosphorylation of IKKβ, IκBα and NF-κB p65, the degradation of IKKβ, IκBα and p65, and the translocation of NF-κB in IL-1β-stimulated chondrocytes. The most significant inhibitory effect of AG was observed at a concentration of 1 mM. Therefore, the present study suggested that AG may serve as a potential agent to reduce the inflammatory response of chondrocytes stimulated by IL-1β.

Role of iNOS in osteoarthritis: Pathological and therapeutic aspects

Accumulating evidence suggests that inflammation has a key role in the pathogenesis of osteoarthritis (OA). Nitric oxide (NO) has been established as one of the major inflammatory mediators in OA and drives many pathological changes during the development and progression of OA. Excessive production of NO in chondrocytes promotes cartilage destruction and cellular injury. The synthesis of NO in chondrocytes is catalyzed by inducible NO synthase (iNOS), which is thereby an attractive therapeutic target for the treatment of OA. A number of direct and indirect iNOS inhibitors, bioactive compounds, and plant-derived small molecules have been shown to exhibit chondroprotective effects by suppressing the expression of iNOS. Many of these iNOS inhibitors hold promise for the development of new, disease-modifying therapies for OA; however, attempts to demonstrate their success in clinical trials are not yet successful. Many plant extracts and plant-derived small molecules have also shown promise in animal models of OA, though further studies are needed in human clinical trials to confirm their therapeutic potential. In this review, we discuss the role of iNOS in OA pathology and the effects of various iNOS inhibitors in OA.

The Link Between Inflammaging and Degenerative Joint Diseases

Aging is an inevitable process in the human body that is associated with a multitude of systemic and localized changes. All these conditions have a common pathogenic mechanism characterized by the presence of a low-grade proinflammatory status. Inflammaging refers to all the processes that contribute to the occurrence of various diseases associated with aging such as frailty, atherosclerosis, Alzheimer’s disease, sarcopenia, type 2 diabetes, or osteoarthritis. Inflammaging is systemic, chronic, and asymptomatic. Osteoarthritis and many age-related degenerative joint diseases are correlated with aging mechanisms such as the presence of an inflammatory microenvironment and the impaired link between inflammasomes and autophagy. There is a close relationship between chondrocyte activity and local articular environment changes due to cell senescence, followed by secretion of inflammatory mediators. In addition, systemic inflammaging can lead to cartilage destruction, pain, disability, and an impaired quality of life. The purpose of this review is to summarize the main mechanisms implicated in inflammaging and the connection it has with degenerative joint diseases.

Resveratrol ameliorates inflammatory damage and protects against osteoarthritis in a rat model of osteoarthritis

Resveratrol is a non-flavonoid polyphenol compound with a stilbene structure. As a type of phytoalexin produced under stress in plants, it improves the plant's resistance against pathogens and environment deterioration, and performs important functions beneficial to human health, such as anti-cancer, anti-oxidation, regulating blood lipid levels and prolonging life span. The effects of resveratrol were examined in a rat model of osteoarthritis (OA) and observed to ameliorate inflammatory damage and protect against OA. In the present study, resveratrol significantly inhibited the induction of clinical scores in rats with OA. Resveratrol inhibited tumor necrosis factor-α, interleukin (IL)-1β, IL-6 and IL-18 expression levels, and decreased caspase-3/9 activity in rats with OA. Inducible nitric oxide synthase, nuclear factor (NF)-κB, phosphorylated-(p)-AMP-activated protein kinase and sirtuin 1 protein expression were significantly suppressed and heme oxygenase 1 (HO-1) and nuclear factor erythroid 2-related factor 2 (Nrf-2) protein expression was stimulated in rats with OA treated with resveratrol. The current results indicate that resveratrol ameliorates inflammatory damage and protects against OA in a rat model of OA via NF-κB and HO-1/Nrf-2 signaling.

A Comparison of the Effects of Neuronal Nitric Oxide Synthase and Inducible Nitric Oxide Synthase Inhibition on Cartilage Damage

The objective of this study was to investigate the effects of selective inducible nitric oxide synthase and neuronal nitric oxide synthase inhibitors on cartilage regeneration. The study involved 27 Wistar rats that were divided into five groups. On Day 1, both knees of 3 rats were resected and placed in a formalin solution as a control group. The remaining 24 rats were separated into 4 groups, and their right knees were surgically damaged. Depending on the groups, the rats were injected with intra-articular normal saline solution, neuronal nitric oxide synthase inhibitor 7-nitroindazole (50 mg/kg), inducible nitric oxide synthase inhibitor amino-guanidine (30 mg/kg), or nitric oxide precursor L-arginine (200 mg/kg). After 21 days, the right and left knees of the rats were resected and placed in formalin solution. The samples were histopathologically examined by a blinded evaluator and scored on 8 parameters. Although selective neuronal nitric oxide synthase inhibition exhibited significant (P = 0.044) positive effects on cartilage regeneration following cartilage damage, it was determined that inducible nitric oxide synthase inhibition had no statistically significant effect on cartilage regeneration. It was observed that the nitric oxide synthase activation triggered advanced arthrosis symptoms, such as osteophyte formation. The fact that selective neuronal nitric oxide synthase inhibitors were observed to have mitigating effects on the severity of the damage may, in the future, influence the development of new agents to be used in the treatment of cartilage disorders.

A Network Pharmacology Approach to Uncover the Pharmacological Mechanism of XuanHuSuo Powder on Osteoarthritis

As the most familiar type of arthritis and a chronic illness of the joints, Osteoarthritis (OA) affects a great number of people on the global scale. XuanHuSuo powder (XHSP), a conventional herbal formula from China, has been extensively applied in OA treatment. Nonetheless, its pharmacological mechanism has not been completely expounded. In this research, a network pharmacology approach has been chosen to study the pharmacological mechanism of XHSP on OA, and the pharmacology networks were established based on the relationship between four herbs found in XHSP, compound targets, and OA targets. The pathway enrichment analysis revealed that the significant bioprocess networks of XHSP on OA were regulation of inflammation, interleukin-1β (IL-1β) production and nitric oxide (NO) biosynthetic process, response to cytokine or estrogen stimuli, and antiapoptosis. These effects have not been reported previously. The comprehensive network pharmacology approach developed by our research has revealed, for the first time, a connection between four herbs found in XHSP, corresponding compound targets, and OA pathway systems that are conducive to expanding the clinical application of XHSP. The proposed network pharmacology approach could be a promising complementary method by which researchers might better evaluate multitarget or multicomponent drugs on a systematic level.

UV-dependent phosphorylation of COP9/signalosome in UV-induced apoptosis

The COP9/signalosome (CSN) multi-protein complex regulates the activity of cullin-RING ubiquitin ligases (CRLs), including the DDB2 and CSA CRL4 ligases (CRL4DDB2 and CRL4CSA), which are involved in the repair of UV-induced DNA damages. In the present study, we demonstrated that the protein kinase ATM, a key component of the DNA damage response (DDR), phosphorylates CSN1 and CSN7a, two subunits of the CSN complex, in a UV-dependent manner. The phosphorylation of CSN1 on serine 474 was detected as early as 3 h after UV-exposure, peaked at 8 h and persisted until 48 h post-UV irradiation. Such a time course suggests a role in late DDR rather than in DNA repair. Consistently, overexpression of a phosphorylation-resistant S474A CSN1 mutant reduced UV-induced apoptosis. Thus, CSN1 appears to play a role not only in DNA repair but also in UV-induced apoptosis.