Targeting macrophagic PIM-1 alleviates osteoarthritis by inhibiting NLRP3 inflammasome activation via suppressing mitochondrial ROS/Cl- efflux signaling pathway

Ion channels in osteoarthritis: emerging roles and potential targets

Osteoarthritis (OA) is a highly prevalent joint disease that causes substantial disability, yet effective approaches to disease prevention or to the delay of OA progression are lacking. Emerging evidence has pinpointed ion channels as pivotal mediators in OA pathogenesis and as promising targets for disease-modifying treatments. Preclinical studies have assessed the potential of a variety of ion channel modulators to modify disease pathways involved in cartilage degeneration, synovial inflammation, bone hyperplasia and pain, and to provide symptomatic relief in models of OA. Some of these modulators are currently being evaluated in clinical trials. This review explores the structures and functions of ion channels, including transient receptor potential channels, Piezo channels, voltage-gated sodium channels, voltage-dependent calcium channels, potassium channels, acid-sensing ion channels, chloride channels and the ATP-dependent P2XR channels in the osteoarthritic joint. The discussion spans channel-targeting drug discovery and potential clinical applications, emphasizing opportunities for further research, and underscoring the growing clinical impact of ion channel biology in OA.

NOX1-mediated oxidative stress induces chondrocyte ferroptosis by inhibiting the Nrf2/HO-1 pathway

Osteoarthritis (OA) is a common joint disease associated with the aging of the population, and it reduces the quality of life of patients. It is characterized by the destruction of articular cartilage and the secretion of inflammatory cytokines. Owing to the unclear pathogenesis of OA, current treatment methods have significant limitations. Oxidative stress has been revealed to play an important role in the development of OA. Our experiments indicated that the levels of GSH decreased and the level of MDA increased in chondrocytes, which induced ferroptosis in chondrocytes in OA. We also revealed that ferroptosis was the main mechanism of cartilage destruction caused by the addition of the ferroptosis activator erastin and the ferroptosis inhibitor ferrostatin-1. NOX1 is the main modulator of oxidative stress by increasing the generation of reactive oxidative species (ROS). We suppressed the expression of NOX1 in chondrocytes through cell transfection. The expression of collagen II and MMP13, and the secretion of IL-1β and TNF-α were reversed. An increase in the mitochondrial membrane potential and a decrease in the level of intracellular ROS indicate an improvement in oxidative damage. Additionally, we determined the effect of the Nrf2/HO-1 pathway on NOX1-mediated chondrocyte injury. We found that NOX1 inhibited the expression of Nrf2/HO-1, but the activation of Nrf2 improved the oxidative damage to chondrocytes in vivo and vitro. This study revealed that NOX1-mediated oxidative stress induces chondrocyte ferroptosis by inhibiting the Nrf2/HO-1 pathway. Our findings contribute to revealing the pathogenesis of OA, providing targets for drug design and optimizing the clinical treatment of OA.

Degrasyn alleviates osteoarthritis by blocking macrophagic pyroptosis via suppressing NLRP3/GSDMD signaling pathway and protecting chondrocytes

Synovitis and cartilage destruction are crucial characteristics of osteoarthritis (OA). Inflammatory cytokines, such as IL-1β, are secreted by synovial macrophages, leading to cartilage destruction. Pyroptosis is a lytic form of programmed cell death, which could be triggered by the NLRP3 inflammasome of macrophages. Pyroptosis promotes the secretion of IL-1β and is supposed as a potential biomarker for OA. However, the function of Pyroptosis and NLRP3 inflammasome and its regulatory mechanism for activation is unclear in OA. In this study, we found that Degrasyn could alleviate the GSDMD-mediated pyroptosis of macrophages and the release of IL-1β, caspase-1, and LDH. Furthermore, it selectively impedes the form of ASC oligomer and speckle to effectively suppress the NLRP3 inflammasome during its assembly phase. Notably, Degrasyn exhibited potential chondroprotective effects in a co-culture system. Additionally, these results also indicate that Degrasyn mitigates synovitis and cartilage damage in a murine model of destabilization of the medial meniscus (DMM)-induced OA. In summary, Degrasyn emerges as a promising pharmaceutical agent for synovitis, paving the way for innovative therapeutic approaches to OA. Our findings underscore the potential of Degrasyn as a viable candidate for OA therapeutics, demonstrating its ability to regulate pyroptosis and NLRP3 inflammasome activation.

New compatible pair of TCM: Paeoniae Radix Alba effectively alleviate Psoraleae Fructus-induced liver injury by suppressing NLRP3 inflammasome activation

Objective

Drug-induced liver injury (DILI), a type of acute inflammation, has sparked significant concern owing to its unpredictability and severity. Psoraleae Fructus (PF), an edible Chinese herb widely used in traditional Chinese medicine (TCM), causes liver injury. Therefore, the elucidation of the mechanism underlying PF-induced liver injury and the search for more effective means of detoxification using herbal compatibility has become an urgent issue. This study evaluated the hepatoprotective effects of Paeoniae Radix Alba (PRA), a hepatoprotective Chinese medicine, on PF-induced liver injury and explored the underlying mechanisms.

Methods

A rat model of lipopolysaccharide (LPS)-induced immune stress was established to evaluate the hepatotoxicity of PF and the detoxifying effect of PRA. Subsequently, inflammatory pathways were identified using network pharmacology. Finally, the molecular mechanism by which PRA alleviates PF-induced liver injury was validated using an inflammasome activation model in bone marrow-derived macrophages (BMDMs).

Results

In vivo, hepatocytes in rats treated with LPS + PF exhibited massive inflammatory infiltration and apoptosis, and the expression of liver injury indicators and inflammatory factors was significantly upregulated, which was reversed by PRA pretreatment. Network pharmacology showed that PRA alleviated PF-induced liver injury and was associated with the NOD-like receptor signaling pathway. Moreover, PF directly induced inflammasome activation in LPS-primed BMDMs which in turn induced caspase-1 activation and the secretion of downstream effector cytokines such as IL-1β. PRA pretreatment inhibited PF-induced activation of the NLRP3 inflammasome by mitigating the accumulation of mitochondrial reactive oxygen species (mtROS).

Conclusions

The present study demonstrates that PRA alleviated PF induced-liver injury by inhibiting NLRP3 inflammasome activation. The results of this study are expected to inform the prevention and control of PF-induced hepatotoxicity in clinical practice.

Pyroptosis: A spoiler of peaceful coexistence between cells in degenerative bone and joint diseases

BACKGROUND

As people age, degenerative bone and joint diseases (DBJDs) become more prevalent. When middle-aged and elderly people are diagnosed with one or more disorders such as osteoporosis (OP), osteoarthritis (OA), and intervertebral disc degeneration (IVDD), it often signals the onset of prolonged pain and reduced functionality. Chronic inflammation has been identified as the underlying cause of various degenerative diseases, including DBJDs. Recently, excessive activation of pyroptosis, a form of programed cell death (PCD) mediated by inflammasomes, has emerged as a primary driver of harmful chronic inflammation. Consequently, pyroptosis has become a potential target for preventing and treating DBJDs.

AIM OF REVIEW

This review explored the physiological and pathological roles of the pyroptosis pathway in bone and joint development and its relation to DBJDs. Meanwhile, it elaborated the molecular mechanisms of pyroptosis within individual cell types in the bone marrow and joints, as well as the interplay among different cell types in the context of DBJDs. Furthermore, this review presented the latest compelling evidence supporting the idea of regulating the pyroptosis pathway for DBJDs treatment, and discussed the potential, limitations, and challenges of various therapeutic strategies involving pyroptosis regulation.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In summary, an interesting identity for the unregulated pyroptosis pathway in the context of DBJDs was proposed in this review, which was undertaken as a spoiler of peaceful coexistence between cells in a degenerative environment. Over the extended course of DBJDs, pyroptosis pathway perpetuated its activity through crosstalk among pyroptosis cascades in different cell types, thus exacerbating the inflammatory environment throughout the entire bone marrow and joint degeneration environment. Correspondingly, pyroptosis regulation therapy emerged as a promising option for clinical treatment of DBJDs.

PiRNA hsa_piR_019949 promotes chondrocyte anabolic metabolism by inhibiting the expression of lncRNA NEAT1

BACKGROUND

Osteoarthritis is a prevalent degenerative joint condition typically found in individuals who are aged 50 years or older. In this study, the focus is on PIWI-interacting RNA (piRNA), which belongs to a category of small non-coding RNAs. These piRNAs play a role in the regulation of gene expression and the preservation of genomic stability. The main objective of this research is to examine the expression of a specific piRNA called hsa_piR_019949 in individuals with osteoarthritis, to understand its impact on chondrocyte metabolism within this condition.

METHODS

We analyzed piRNA expression in osteoarthritis cartilage using the GEO database. To understand the impact of inflammatory factors on piRNA expression in chondrocytes, we conducted RT-qPCR experiments. We also investigated the effect of piRNA hsa_piR_019949 on chondrocyte proliferation using CCK-8 and clone formation assays. Furthermore, we assessed the influence of piRNA hsa_piR_019949 on chondrocyte apoptosis by conducting flow cytometry analysis. Additionally, we examined the differences in cartilage matrix composition through safranine O staining and explored the downstream regulatory mechanisms of piRNA using transcriptome sequencing. Lentiviral transfection of NEAT1 and NLRP3 was performed to regulate the metabolism of chondrocytes.

RESULTS

Using RNA sequencing technology, we compared the gene expression profiles of 5 patients with osteoarthritis to 3 normal controls. We found a gene called hsa_piR_019949 that showed differential expression between the two groups. Specifically, hsa_piR_019949 was downregulated in chondrocytes when stimulated by IL-1β, an inflammatory molecule. In further investigations, we discovered that overexpression of hsa_piR_019949 in vitro led to increased proliferation and synthesis of the extracellular matrix in chondrocytes, which are cells responsible for cartilage formation. Conversely, suppressing hsa_piR_019949 expression resulted in increased apoptosis (cell death) and degradation of the extracellular matrix in chondrocytes. Additionally, we found that the NOD-like receptor signaling pathway is linked to the low expression of hsa_piR_019949 in a specific chondrocyte cell line called C28/I2. Furthermore, we observed that hsa_piR_019949 can inhibit the expression of a long non-coding RNA called NEAT1 in chondrocytes. We hypothesize that NEAT1 may serve as a downstream target gene regulated by hsa_piR_019949, potentially influencing chondrocyte metabolism and function in the context of osteoarthritis.

CONCLUSIONS

PiRNA hsa_piR_019949 has shown potential in promoting the proliferation of chondrocytes and facilitating the synthesis of extracellular matrix in individuals with osteoarthritis. This is achieved by inhibiting the expression of a long non-coding RNA called NEAT1. The implication is that by using hsa_piR_019949 mimics, which are synthetic versions of the piRNA, as a therapeutic approach, it may be possible to effectively treat osteoarthritis.