The Impact of NLRP3 Inflammasome on Osteoblasts and Osteogenic Differentiation: A Literature Review.

Osteoblasts (OBs), which are a crucial type of bone cells, derive from bone marrow mesenchymal stem cells (MSCs). Accumulating evidence suggests inflammatory cytokines can inhibit the differentiation and proliferation of OBs, as well as interfere with their ability to synthesize bone matrix, under inflammatory conditions. NLRP3 inflammasome is closely associated with cellular pyroptosis, which can lead to excessive release of pro-inflammatory cytokines, causing tissue damage and inflammatory responses, however, the comprehensive roles of NLRP3 inflammasome in OBs and their differentiation have not been fully elucidated, making targeting NLRP3 inflammasome approaches to treat diseases related to OBs uncertain. In this review, we provide a summary of NLRP3 inflammasome activation and its impact on OBs. We highlight the significant roles of NLRP3 inflammasome in regulating OBs differentiation and function. Furthermore, current available strategies to affect OBs function and osteogenic differentiation targeting NLRP3 inflammasome are listed and analyzed. Finally, through the prospective discussion, we seek to provide novel insights into the crucial role of NLRP3 inflammasome in diseases related to OBs and offer valuable information for devising treatment strategies.

Targeting cellular senescence in senile osteoporosis: therapeutic potential of traditional Chinese medicine.

Senile osteoporosis (SOP) is a prevalent manifestation of age-related bone disorders, resulting from the dysregulation between osteoblast (OB)-mediated bone formation and osteoclast (OC)-mediated bone resorption, coupled with the escalating burden of cellular senescence. Traditional Chinese medicine (TCM) herbs, renowned for their remarkable attributes encompassing excellent tolerability, low toxicity, heightened efficacy, and minimal adverse reactions, have gained considerable traction in OP treatment. Emerging evidence substantiates the therapeutic benefits of various TCM formulations and their active constituents, including Zuogui wan, Fructus Ligustri Lucidi, and Resveratrol, in targeting cellular senescence to address SOP. However, a comprehensive review focusing on the therapeutic efficacy of TCM against SOP, with a particular emphasis on senescence, is currently lacking. In this review, we illuminate the pivotal involvement of cellular senescence in SOP and present a comprehensive exploration of TCM formulations and their active ingredients derived from TCM, delineating their potential in SOP treatment through their anti-senescence properties. Notably, we highlight their profound effects on distinct aging models that simulate SOP and various senescence characteristics. Finally, we provide a forward-looking discussion on utilizing TCM as a strategy for targeting cellular senescence and advancing SOP treatment. Our objective is to contribute to the unveiling of safer and more efficacious therapeutic agents for managing SOP.

Inhibition of Caspase-1-mediated pyroptosis promotes osteogenic differentiation, offering a therapeutic target for osteoporosis.

BACKGROUND: Pyroptosis, an emerging inflammatory form of cell death, has been previously demonstrated to stimulate a massive inflammatory response, thus hindering the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Nevertheless, the impact of pyroptosis in thwarting osteogenic differentiation and exacerbating the advancement of osteoporosis (OP) remains enigmatic. METHODS: We evaluated the expression levels of pyroptosis-associated indicators, including NOD-like receptor family pyrin domain-containing protein 3 (NLRP3), CASPASE-1, IL-1ß, and IL-18, in specimens obtained from femoral heads of OP patients, as well as in an ovariectomy-induced mouse model of OP. Subsequently, the precise roles of pyroptosis in osteogenic differentiation were investigated using bioinformatics analysis, alongside morphological and biochemical assessments. RESULTS: The pivotal pyroptotic proteins, including NLRP3, Caspase-1, IL-1ß, and IL-18, exhibited significant upregulation within the bone tissue samples of clinical OP cases, as well as in the femoral tissues of ovariectomy (OVX)-induced mouse OP model, displaying a negatively associated with compromised osteogenic capacity, as represented by lessened bone mass, suppressed expression of osteogenic proteins such as Runt-related transcription factor 2 (RUNX2), Alkaline phosphatase (ALP), Osterix (OSX), and Osteopontin (OPN), and increased lipid droplets. Moreover, bioinformatics analysis substantiated shared gene expression patterns between pyroptosis and OP pathology, encompassing NLRP3, Caspase-1, IL-1ß, IL-18, etc. Furthermore, our in vitro investigation using ST2 cells revealed that dexamethasone treatment prominently induced pyroptosis while impeding osteogenic differentiation. Notably, gene silencing of Caspase-1 effectively counteracted the inhibitory effects of dexamethasone on osteogenic differentiation, as manifested by increased ALP activity and enhanced expression of RUNX2, ALP, OSX, and OPN. CONCLUSION: Our findings unequivocally underscore that inhibition of Caspase-1-mediated pyroptosis promotes osteogenic differentiation, providing a promising therapeutic target for managing OP.

Mechanisms of action and synergetic formulas of plant-based natural compounds from traditional Chinese medicine for managing osteoporosis: a literature review.

Osteoporosis (OP) is a systemic skeletal disease prevalent in older adults, characterized by substantial bone loss and deterioration of microstructure, resulting in heightened bone fragility and risk of fracture. Traditional Chinese Medicine (TCM) herbs have been widely employed in OP treatment owing to their advantages, such as good tolerance, low toxicity, high efficiency, and minimal adverse reactions. Increasing evidence also reveals that many plant-based compounds (or secondary metabolites) from these TCM formulas, such as resveratrol, naringin, and ginsenoside, have demonstrated beneficial effects in reducing the risk of OP. Nonetheless, the comprehensive roles of these natural products in OP have not been thoroughly clarified, impeding the development of synergistic formulas for optimal OP treatment. In this review, we sum up the pathological mechanisms of OP based on evidence from basic and clinical research; emphasis is placed on the in vitro and preclinical in vivo evidence-based anti-OP mechanisms of TCM formulas and their chemically active plant constituents, especially their effects on imbalanced bone homeostasis regulated by osteoblasts (responsible for bone formation), osteoclasts (responsible for bone resorption), bone marrow mesenchymal stem cells as well as bone microstructure, angiogenesis, and immune system. Furthermore, we prospectively discuss the combinatory ingredients from natural products from these TCM formulas. Our goal is to improve comprehension of the pharmacological mechanisms of TCM formulas and their chemically active constituents, which could inform the development of new strategies for managing OP.

Cadmium exposure promotes thyroid pyroptosis and endocrine dysfunction by inhibiting Nrf2/Keap1 signaling.

Cadmium (Cd) is a ubiquitous toxic metal and environmental pollutant. Increasing studies have shown that Cd exposure increases the incidence of various endocrine system diseases, including thyrotoxicity reflected by thyroid structural damage and endocrine toxicity. However, the observed outcomes are complex and conflicting, leading to the mechanism of Cd-induced thyrotoxicity remaining obscure. In this study, 4-week-old male C57BL/6 mice were given 2 or 7 mg/kg Cadmium Chloride (CdCl2) intragastrically for 4 and 8 weeks, and the Cd-mediated thyrotoxicity was evaluated by determining alterations in thyroid structure and endocrine function, and alterations of oxidant stress, apoptosis, and pyroptosis. Our data showed that Cd exposure could reduce body weight and induce thyrotoxicity by impairing thyroid follicular morphology and endocrine function, accompanied by elevated oxidative stress and apoptosis, macrophage infiltration, and inflammatory cytokine secretion. Importantly, Cd significantly promoted thyroid follicular cell pyroptosis by increasing Nlrp3, Asc, Caspase-1, Gsdmd, IL-1ß, and IL-18 expression. Mechanistical analysis suggested that Cd treatment could inhibit antioxidant pathway by downregulating antioxidant response protein, Nrf2, and upregulating its negative feedback regulator, Keap1. Collectively, our in vivo findings suggest that Cd exposure could facilitate thyroid follicular cell pyroptosis by inhibiting Nrf2/Keap1 signaling, thereby disrupting thyroid tissue structure and endocrine function, which offers novel insights into the Cd-mediated detrimental consequences on thyroid homeostasis.

α-Chaconine Facilitates Chondrocyte Pyroptosis and Nerve Ingrowth to Aggravate Osteoarthritis Progression by Activating NF-κB Signaling.

Background: With the rapid growth of the elderly population, the incidence of osteoarthritis (OA) increases annually, which has attracted extensive attention in public health. The roles of dietary intake in controlling joint disorders are perhaps one of the most frequently posed questions by OA patients, while the information about the interaction between dietary intake and OA based on scientific research is limited. α-Chaconine is the richest glycoalkaloid in eggplants such as potatoes. Previous evidence suggests that α-Chaconine is a toxic compound to nervous and digestive systems with potentially severe and fatal consequences for humans and farm animals, but its effect on OA development remains obscure. Objective: To determine whether α-Chaconine deteriorates OA progression through sensory innervation and chondrocyte pyroptosis via regulating nuclear factor-κB (NF-κB) signaling, providing evidence for a possible linkage between α-Chaconine and OA progression. Methods: We established a mouse OA model by destabilization of medial meniscus (DMM) surgery and then intra-articular injection of 20 or 100 µM α-Chaconine into the OA mice for 8 and 12 weeks. The severity of OA progression was evaluated by histological staining and radiographic analyses. The expressions of matrix metabolic indicators, Col2, Mmp3, and Mmp13, as well as pyroptosis-related proteins, Nlrp3, Caspase-1, Gsdmd, IL-1ß, IL-18, were determined by immunohistochemistry. And the changes in sensory nerve ingrowth and activity of NF-κB signaling were determined by immunofluorescence. Results: We found that α-Chaconine could exacerbate mouse OA progression, resulting in subchondral sclerosis, osteophyte formation, and higher OARSI scores. Specifically, α-Chaconine could augment cartilage matrix degradation and induce chondrocyte pyroptosis and nerve ingrowth. Mechanistical analysis revealed that α-Chaconine stimulated NF-κB signaling by promoting I-κB α phosphorylation and p65 nuclear translocation. Conclusion: Collectively, our findings raise the possibility that α-Chaconine intake can boost chondrocyte pyroptosis and nerve ingrowth to potentiate OA progression by activating NF-κB signaling.

Morroniside attenuates nucleus pulposus cell senescence to alleviate intervertebral disc degeneration via inhibiting ROS-Hippo-p53 pathway.

Intervertebral disc (IVD) degeneration (IVDD) which is highly prevalent within the elderly population, is a leading cause of chronic low back pain and disability. Nucleus pulposus (NP) cell senescence plays an indispensable role in the pathogenesis of IVDD. Morroniside is a major iridoid glycoside and one of the quality control metrics of Cornus officinalis Siebold & Zucc (CO). An increasing body of evidence suggests that morroniside and CO-containing formulae share many similar biological effects, including anti-inflammatory, anti-oxidative, and anti-apoptotic properties. In a previous study, we reported that Liuwei Dihuang Decoction, a CO-containing formula, is effective for treating IVDD by targeting p53 expression; however, the therapeutic role of morroniside on IVDD remains obscure. In this study, we assessed the pharmacological effects of morroniside on NP cell senescence and IVDD pathogenesis using a lumbar spine instability surgery-induced mouse IVDD model and an in vitro H2O2-induced NP cell senescence model. Our results demonstrated that morroniside administration could significantly ameliorate mouse IVDD progression, concomitant with substantial improvement in extracellular matrix metabolism and histological grading score. Importantly, in vivo and in vitro experiments revealed that morroniside could significantly reduce the increase in SA-ß-gal activities and the expression of p53 and p21, which are the most widely used indicators of senescence. Mechanistically, morroniside suppressed ROS-induced aberrant activation of Hippo signaling by inhibiting Mst1/2 and Lats1/2 phosphorylation and reversing Yap/Taz reduction, whereas blockade of Hippo signaling by Yap/Taz inhibitor-1 or Yap/Taz siRNAs could antagonize the anti-senescence effect of morroniside on H2O2-induced NP cell senescence model by increasing p53 expression and activity. Moreover, the inhibition of Hippo signaling in the IVD tissues by morroniside was further verified in mouse IVDD model. Taken together, our findings suggest that morroniside protects against NP cell senescence to alleviate IVDD progression by inhibiting the ROS-Hippo-p53 pathway, providing a potential novel therapeutic approach for IVDD.

Corrective Osteotomy with Volar and Dorsal Fixation for Malunion of Intra-Articular Fracture of the Distal Radius: A Retrospective Study.

OBJECTIVES: Although corrective osteotomy with volar or dorsal plate fixation can treat malunion of distal radius fractures, each has its own disadvantages. Little is currently known on whether dorsal fixation combined with volar fixation may further improve recovery. This study aimed to evaluate the clinical value of corrective osteotomy combined with volar and dorsal plate fixation in patients with malunion of intra-articular fractures of the distal radius. METHODS: Seventeen patients with malunion of intra-articular fractures of the distal radius treated with corrective osteotomy with volar and dorsal plate fixation from 1 January 2016 to 31 November 2018 were retrospectively analyzed. The enrolled patients included seven males and 10 females with an average age of 54.9 years (range: 36-70 years). The radiographic parameters, including the radial length, the radial inclination angle, the ulnar variance, and the volar tilt, as well as clinical outcomes, including wrist and forearm range of motion (ROM), grip strength, the Mayo Modified Wrist Score (MMWS), and the disabilities of the Arm, Shoulder, and Hand (DASH) score, were examined at 3 months and 18 months after operation and compared with the preoperative state. The paired t-test was used for statistical analysis. RESULTS: After corrective osteotomy combined with volar and dorsal plate fixation, all included patients were followed up for 18 months, and there was no surgical site infection. Patients reported postoperative pain due to the irritation of extensor tendon (two cases) and wrist arthritis (two cases). The radial length increased from 1.34 ± 2.34 mm to 9.25 ± 2.65 mm and 9.03 ± 2.47 mm at 3 months and 18 months postoperatively (t = 8.257, 7.954, all p < 0.05). The radial inclination angle increased from 6.45° ± 0.76° to 19.35° ± 3.43° and 19.03° ± 3.63° at 3 and 18 months (t = 12.517, 12.122, all p < 0.05). The ulnar variance decreased from 5.11 ± 0.23 mm to 1.32 ± 0.31 mm and 1.54 ± 0.62 mm at 3 and 18 months (t = 4.214, 4.895, all p < 0.05). The volar tilt was corrected from 4.47° ± 3.46° to 15.51° ± 2.72° and 14.12° ± 2.41°, respectively (t = 11.247, 10.432, all p < 0.05). Moreover, wrist ROM increased from 42.53° ± 8.99° to 98.70° ± 7.61° and 101.24° ± 7.66° (t = 41.433, 46.627, all p < 0.05), while forearm ROM was increased from 94.82° ± 6.54° to 134.47° ± 5.06° and 137.24° ± 5.52°, respectively (t = 31.507, 32.584, all p < 0.05). Similarly, grip strength, MMWS, and DASH were also remarkably improved. There were no significant differences in the wrist and forearm ROM, grip strength, MMWS, and DASH scores between follow-up at 3 and 18 months (all p > 0.05). CONCLUSIONS: Corrective osteotomy with volar and dorsal fixation can improve recovery of volar tilt, relieve wrist pain, restore wrist and forearm function, and increase grip strength of patients with malunion of intra-articular fractures of the distal radius.

Network Pharmacology and Experimental Validation to Reveal the Pharmacological Mechanisms of Liuwei Dihuang Decoction Against Intervertebral Disc Degeneration.

PURPOSE: To explore the pharmacological mechanisms of Liuwei Dihuang Decoction (LWDHD) against intervertebral disc (IVD) degeneration (IVDD) via network pharmacology analysis combined with experimental validation. METHODS: First, active ingredients and related targets of LWDHD, as well as related genes of IVDD, were collected from public databases. The protein-protein interaction (PPI) network, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analyses were performed to predict the core targets and pathways of LWDHD against IVDD. Secondly, the IVDD model of mice treated with LWDHD was selected to validate the major targets predicted by network pharmacology. RESULTS: By searching the intersection of the active ingredient targets and IVDD targets, a total of 110 targets matched the related targets of 30 active ingredients in LWDHD and IVDD were retrieved. PPI network analysis indicated that 17 targets, including Caspase-3, IL-1ß, P53, etc., were hub targets. GO and KEGG enrichment analyses showed that the apoptosis pathway was enriched by multiple targets and served as the target for in vivo experimental study validation. The results of animal experiments revealed that LWDHD administration not only restored the decrease in disc height and abnormal degradation of matrix metabolism in IVDD mice but also reversed the high expression of Bax, Caspase-3, IL-1ß, P53, and low expression of Bcl-2, thereby inhibiting the apoptosis of IVD tissue and ameliorating the progression of IVDD. CONCLUSION: Using a comprehensive network pharmacology approach, our findings predicted the active ingredients and potential targets of LWDHD intervention for IVDD, and some major target proteins involved in the predictive signaling pathway were validated experimentally, which gave us a new understanding of the pharmacological mechanism of LWDHD in treating IVDD at the comprehensive level.

Aberrant spinal mechanical loading stress triggers intervertebral disc degeneration by inducing pyroptosis and nerve ingrowth.

Aberrant mechanical factor is one of the etiologies of the intervertebral disc (IVD) degeneration (IVDD). However, the exact molecular mechanism of spinal mechanical loading stress-induced IVDD has yet to be elucidated due to a lack of an ideal and stable IVDD animal model. The present study aimed to establish a stable IVDD mouse model and evaluated the effect of aberrant spinal mechanical loading on the pathogenesis of IVDD. Eight-week-old male mice were treated with lumbar spine instability (LSI) surgery to induce IVDD. The progression of IVDD was evaluated by µCT and Safranin O/Fast green staining analysis. The metabolism of extracellular matrix, ingrowth of sensory nerves, pyroptosis in IVDs tissues were determined by immunohistological or real-time PCR analysis. The apoptosis of IVD cells was tested by TUNEL assay. IVDD modeling was successfully produced by LSI surgery, with substantial reductions in IVD height, BS/TV, Tb.N. and lower IVD score. LSI administration led to the histologic change of disc degeneration, disruption of the matrix metabolism, promotion of apoptosis of IVD cells and invasion of sensory nerves into annulus fibrosus, as well as induction of pyroptosis. Moreover, LSI surgery activated Wnt signaling in IVD tissues. Mechanical instability caused by LSI surgery accelerates the disc matrix degradation, nerve invasion, pyroptosis, and eventually lead to IVDD, which provided an alternative mouse IVDD model.

Integration of Network Pharmacology and Experimental Validation to Explore the Pharmacological Mechanisms of Zhuanggu Busui Formula Against Osteoporosis.

Osteoporosis (OP) is a common skeletal disease, characterized by decreased bone formation and increased bone resorption. As a novel Chinese medicine formula, Zhuanggu Busui formula (ZGBSF) has been proved to be an effective prescription for treating OP in clinic, however, the pharmacological mechanisms underlying the beneficial effects remain obscure. In this study, we explored the pharmacological mechanisms of ZGBSF against OP via network pharmacology analysis coupled with in vivo experimental validation. The results of the network pharmacology analysis showed that a total of 86 active ingredients and 164 targets of ZGBSF associated with OP were retrieved from the corresponding databases, forming an ingredient-target-disease network. The protein-protein interaction (PPI) network manifested that 22 core targets, including Caspase-3, BCL2L1, TP53, Akt1, etc, were hub targets. Moreover, functional enrichment analyses revealed that PI3K-Akt and apoptosis signalings were significantly enriched by multiple targets and served as the targets for in vivo experimental study validation. The results of animal experiments revealed that ZGBSF not only reversed the high expression of Caspase-3, Bax, Prap, and low expression of Bcl-2 in osteoblasts of the OP mouse model but also contributed to the phosphorylation of Akt1 and expression of PI3K, thereby promoting osteogenesis and ameliorating the progression of OP. In conclusion, this study systematically and intuitively illustrated that the possible pharmacological mechanisms of ZGBSF against OP through multiple ingredients, targets, and signalings, and especially the inhibition of the apoptosis and the activation of PI3K-Akt signaling.

Comparative intra-articular gene transfer of seven adeno-associated virus serotypes reveals that AAV2 mediates the most efficient transduction to mouse arthritic chondrocytes.

Osteoarthritis (OA) is the most common arthropathy, characterized by progressive degeneration of the articular cartilage. Currently, there are no disease-modifying approaches for OA treatment. Adeno-associated virus (AAV)-mediated gene therapy has recently become a potential treatment for OA due to its exceptional characteristics; however, the tropism and transduction efficiency of different AAV serotypes to articular joints and the safety profile of AAV applications are still unknown. The present study aims to screen an ideal AAV serotype to efficiently transfer genes to arthritic cartilage. AAV vectors of different serotypes expressing eGFP protein were injected into the knee joint cavities of mice, with all joint tissues collected 30 days after AAV injection. The transduction efficiency of AAVs was quantified by assessing the fluorescent intensities of eGFP in the cartilage of knee joints. Structural and morphological changes were analyzed by toluidine blue staining. Changes to ECM metabolism and pyroptosis of chondrocytes were determined by immunohistochemical staining. Fluorescence analysis of eGFP showed that eGFP was expressed in the cartilage of knee joints injected with each AAV vector. Quantification of eGFP intensity indicated that AAV2, 7 and 8 had the highest transduction efficiencies. Both toluidine blue staining and Mankin score showed that AAV6 aggravated cartilage degeneration. The analysis of key molecules in ECM metabolism suggested that AAV5 and 7 significantly reduced collagen type II, while AAV9 increased ADAMTS-4 but decreased MMP-19. In addition, transduction with AAV2, 5, 7 and 8 had no obvious effect on pyroptosis of chondrocytes. Comprehensive score analysis also showed that AAV2 had the highest score in intra-articular gene transfer. Collectively, our findings point to AAV2 as the best AAV serotype candidate for gene transfer on arthritic cartilage, resulting in minimal impact to ECM metabolism and pyroptosis of chondrocytes.