Andrographolide suppresses osteoarthritis progression by regulating circ_Rapgef1/miR-383-3p/NLRP3 signaling axis

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.

Three-Dimensional Bioprinting of Growth Differentiation Factor 5-Preconditioned Mesenchymal Stem Cell-Derived Exosomes Facilitates Articular Cartilage Endogenous Regeneration

The repair of articular cartilage defects remains a major regenerative and clinical challenge. Exosomes (Exos) derived from mesenchymal stem cells (MSCs) have good application potential in cartilage tissue engineering. Numerous studies have indicated that appropriate preconditioning methods can promote the therapeutic effect of Exos. Growth differentiation factor 5 (GDF-5) plays a critical role in chondrogenesis and regeneration. In this study, GDF-5 was used to precondition synovial mesenchymal stem cells (SMSCs) to increase the chondrogenic-promoting effect of Exos (G-Exos). In addition, we demonstrated that G-Exos rich in miR-383-3p increased the chondrogenic potential of SMSCs by activating the Kdm2a/SOX2 signaling pathway. On this basis, G-Exos were loaded into a glycyrrhizic acid/methacrylate-acylated hyaluronic acid (GA/HA/G-Exos) scaffold via digital light processing (DLP) bioprinting to maintain bioactivity and sustained release. The GA/HA/G-Exos scaffolds not only presented significant biological properties in vitro but also significantly promoted the remodeling of the joint cavity regenerative microenvironment and the regeneration of articular cartilage in Sprague-Dawley rats. This study provides a promising cell-free regenerative strategy for cartilage defect repair via the use of engineered exofunctionalized biological scaffolds.

Andrographolide represses HIF-1α and VEGFA expression, thus inhibiting hypoxia-induced proliferation, oxidative stress, and inflammatory cytokine secretion in human keratinocytes

Epidermal hypoxia, hyperproliferation of keratinocytes, and inflammation in skin lesions are relevant to the pathogenesis of inflammatory skin diseases, including psoriasis. Andrographolide (Andro) is a natural labdane diterpene with diverse biofunctions. Andro has been reported to alleviate psoriasis in mice. However, the exact mechanisms need further study. Our results demonstrated that Andro inhibited hypoxia-induced proliferation of human keratinocytes. Andro also protected the keratinocytes from hypoxia-induced oxidative stress and inflammatory response. Furthermore, we found that Andro suppressed the expression of HIF-1α and VEGFA expression in hypoxia-exposed keratinocytes. Overexpression of either HIF-1α or VEGFA attenuated the inhibitory effects of Andro on hypoxia-induced proliferation, oxidative stress, and inflammatory cytokine secretion. In summary, our results demonstrated that Andro protected keratinocytes from hypoxia-induced proliferation, oxidative stress, and inflammatory cytokine secretion by suppressing HIF-1α and VEGFA expression. Our findings provide an unreported insight into the potential use of Andro as an effective agent for the treatment of inflammatory skin diseases such as psoriasis in the future.

Injectable sustainable andrographolide-releasing hydrogel for long-lasting alleviation of osteoarthritis and regulation of chondrocyte autophagy via PRKCA/EGFR

Osteoarthritis is one of the most prevalent age-related joint diseases, with chondrocyte inflammation and autophagy dysregulation serving as pivotal pathogenesis factors. Andrographolide (AD), a phytochemical identified in Andrographis paniculata, exhibits anti-inflammatory properties and regulates autophagy to safeguard cells from damage. Nevertheless, the precise mechanism underlying the influence of AD on autophagy in osteoarthritis (OA) chondrocytes remains unelucidated. Concurrently, sustained efficacy of andrographolide typically necessitates prolonged administration, posing a challenge for its clinical application. We engineered an injectable 4-arm PEG-Mix-Hydrogel/PF system capable of encapsulating lipophilic drugs and achieving sustained release over a period of up to 24 days, substantially reducing the frequency of medication. Our findings indicate that andrographolide augments chondrocyte autophagy via the PRKCA/EGFR pathway and modulates chondrocyte inflammation as well as extracellular matrix degradation. Subsequent experimentation revealed that the injectable 4-arm PEG-Mix-Hydrogel/PF@AD (PHPF@AD) exhibited excellent biocompatibility with chondrocytes, possessed a rapid in-situ gelation time, and a single injection was sufficient to alleviate joint degeneration, abnormal gait, and weakened chondrocyte autophagy in OA mice, while ameliorating inflammation, matrix degradation, and apoptosis levels, and maintaining a certain degree of bone mass around the joints. In summary, this injectable hydrogel with spontaneous andrographolide release is anticipated to be a promising therapeutic modality for OA.

Elucidation of the key therapeutic targets and potential mechanisms of Andrographolide multi-targets against osteoarthritis via network pharmacological analysis and experimental validation

OBJECTIVE

Our purpose is to unveil Andrographolide's potential multi-target and multi-mechanism therapeutic effects in treating OA via systematic network pharmacological analysis and cell experimental validation.

MATERIALS AND METHODS

Initially, we gathered data from Andrographolide and OA-related databases to obtain information on Andrographolide's biological properties and the targets linked with OA. We developed a bioinformatic network about Andrographolide and OA, whereby we analyzed the network to identify potential therapeutic targets and mechanisms of action of Andrographolide. Subsequently, we used molecular docking to analyze the binding sites of Andrographolide to the target proteins. At the same time, SDF-1 was used to construct an OA cell model to verify the therapeutic effect of Andrographolide on OA and its effect on target proteins.

RESULTS

Our experimental results show that Andrographolide has excellent pharmaceutical properties, by Lipinski's rules for drugs, suggesting that this compound can be considered to have a high therapeutic potential in drug development. 233 targets were preliminarily investigated, the mechanisms through which Andrographolide targets OA primarily involve the TNF signaling pathway, PI3K-AKT signaling pathway, IL-17 signaling pathway, and TLR signaling pathway. These mechanisms target OA by influencing immune and inflammatory responses in the joints, regulating apoptosis to prevent chondrocyte death. Finally, TNF-α, STAT3, TP53, IL-6, JUN, IL-1β, HIF-1α, TGF-β1, and AKT1 were identified as 9 key targets of Andrographolide anti-OA. In addition, our molecular docking analyzes with cell experimental validation further confirm the network pharmacology results. According to our molecular docking results, Andrographolide can bind to all the hub target proteins and has a good binding ability (binding energy < -5 kcal/mol), with the strongest binding affinity to AKT1 of -9.2 kcal/ mol. The results of cell experiments showed that Andrographolide treatment significantly increased the cell viability and the expression of COL2A1 and ACAN proteins. Moreover, 30 μM Andrographolide significantly reversed SDF-1-induced increases in the protein expression of TNF-α, STAT3, TP53, IL-6, JUN, IL-1β, HIF-1α, and TGF-β1, and decreases in the protein expression of AKT1.

CONCLUSION

This study provides a comprehensive understanding of the potential therapeutic targets and mechanisms of action of Andrographolide in OA treatment. Our findings suggest that Andrographolide is a promising candidate for drug development in the management of OA.

CircRNAs in osteoarthritis: research status and prospect

Osteoarthritis (OA) is the most common joint disease globally, and its progression is irreversible. The mechanism of osteoarthritis is not fully understood. Research on the molecular biological mechanism of OA is deepening, among which epigenetics, especially noncoding RNA, is an emerging hotspot. CircRNA is a unique circular noncoding RNA not degraded by RNase R, so it is a possible clinical target and biomarker. Many studies have found that circRNAs play an essential role in the progression of OA, including extracellular matrix metabolism, autophagy, apoptosis, the proliferation of chondrocytes, inflammation, oxidative stress, cartilage development, and chondrogenic differentiation. Differential expression of circRNAs was also observed in the synovium and subchondral bone in the OA joint. In terms of mechanism, existing studies have mainly found that circRNA adsorbs miRNA through the ceRNA mechanism, and a few studies have found that circRNA can serve as a scaffold for protein reactions. In terms of clinical transformation, circRNAs are considered promising biomarkers, but no large cohort has tested their diagnostic value. Meanwhile, some studies have used circRNAs loaded in extracellular vesicles for OA precision medicine. However, there are still many problems to be solved in the research, such as the role of circRNA in different OA stages or OA subtypes, the construction of animal models of circRNA knockout, and more research on the mechanism of circRNA. In general, circRNAs have a regulatory role in OA and have particular clinical potential, but further studies are needed in the future.

CircRNA-mediated ceRNA mechanism in Osteoarthritis: special emphasis on circRNAs in exosomes and the crosstalk of circRNAs and RNA methylation

Osteoarthritis (OA) is an age-related joint disease with chronic inflammation, progressive articular cartilage destruction and subchondral bone sclerosis. CircRNAs (circRNAs) are a class of non-coding RNA with a circular structure that participate in a series of important pathophysiological processes of OA, especially its ceRNA mechanisms, and play an important role in OA. CircRNAs may be potential biomarkers for the diagnosis and prognosis of OA. Additionally, differentially expressed circRNAs were found in patients with OA, indicating that circRNAs are involved in the pathogenesis of OA. Experiments have shown that the intra-articular injection of modified circRNAs can effectively relieve OA. Exosomal circRNAs and methylated circRNAs also provide new ideas for the treatment of OA. Clarifying the important roles of circRNAs in OA will deepen people's understanding of the pathogenesis of OA. CircRNAs may be developed as new biomarkers or drug targets for the diagnosis of OA and provide new methods for the treatment of OA.

Mechanism of NLRP3 inflammasome intervention for synovitis in knee osteoarthritis: A review of TCM intervention

Objective: This paper briefly reviews the structure and function of NLRP3 inflammasomes, signaling pathway, relationship with synovitis in KOA, and intervention of traditional Chinese medicine (TCM) in NLRP3 inflammasomes as a means to improve its therapeutic potential and clinical application.

Method: Literatures about NLRP3 inflammasomes and synovitis in KOA were reviewed to analyze and discuss.

Result: NLRP3 inflammasome can activate NF-κB mediated signal transduction, which in turn causes the expression of proinflammatory cytokines, initiates the innate immune response, and triggers synovitis in KOA. The TCM monomer/active ingredient, decoction, external ointment, and acupuncture regulating NLRP3 inflammasomes are helpful to alleviate synovitis in KOA.

Conclusion: The NLRP3 inflammasome plays a significant role in the pathogenesis of synovitis in KOA, TCM intervention targeting the NLRP3 inflammasome can be a novel approach and therapeutic direction for the treatment of synovitis in KOA.

The role of NLRP3 inflammasome in inflammation-related skeletal muscle atrophy

Skeletal muscle atrophy is a common complication in survivors of sepsis, which affects the respiratory and motor functions of patients, thus severely impacting their quality of life and long-term survival. Although several advances have been made in investigations on the pathogenetic mechanism of sepsis-induced skeletal muscle atrophy, the underlying mechanisms remain unclear. Findings from recent studies suggest that the nucleotide-binding and oligomerisation domain (NOD)-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, a regulator of inflammation, may be crucial in the development of skeletal muscle atrophy. NLRP3 inhibitors contribute to the inhibition of catabolic processes, skeletal muscle atrophy and cachexia-induced inflammation. Here, we review the mechanisms by which NLRP3 mediates these responses and analyse how NLRP3 affects muscle wasting during inflammation.

Andrographolide, a natural anti-inflammatory agent: An Update

Botanicals have attracted much attention in the field of anti-inflammatory due to their good pharmacological activity and efficacy. Andrographis paniculata is a natural plant ingredient that is widely used around the world. Andrographolide is the main active ingredient derived from Andrographis paniculata, which has a good effect on the treatment of inflammatory diseases. This article reviews the application, anti-inflammatory mechanism and molecular targets of andrographolide in different inflammatory diseases, including respiratory, digestive, immune, nervous, cardiovascular, skeletal, and tumor system diseases. And describe its toxicity and explain its safety. Studies have shown that andrographolide can be used to treat inflammatory lesions of various systemic diseases. In particular, it acts on many inflammation-related signalling pathways. The future direction of andrographolide research is also introduced, as is the recent research that indicates its potential clinical application as an anti-inflammatory agent.

Activation and Pharmacological Regulation of Inflammasomes

Inflammasomes are intracellular signaling complexes of the innate immune system, which is part of the response to exogenous pathogens or physiological aberration. The multiprotein complexes mainly consist of sensor proteins, adaptors, and pro-caspase-1. The assembly of the inflammasome upon extracellular and intracellular cues drives the activation of caspase-1, which processes pro-inflammatory cytokines IL-1β and IL-18 to maturation and gasdermin-D for pore formation, leading to pyroptosis and cytokine release. Inflammasome signaling functions in numerous infectious or sterile inflammatory diseases, including inherited autoinflammatory diseases, metabolic disorders, cardiovascular diseases, cancers, neurodegenerative disorders, and COVID-19. In this review, we summarized current ideas on the organization and activation of inflammasomes, with details on the molecular mechanisms, regulations, and interventions. The recent developments of pharmacological strategies targeting inflammasomes as disease therapeutics were also covered.