Effects of short-duration treatment of cartilage with punicalagin and genipin and the implications for treatment of osteoarthritis

Development of in situ forming implants for controlled delivery of punicalagin

Due to efficient drainage of the joint, the development of intra-articular depots for long-lasting drug release is a difficult challenge. Moreover, a disease-modifying osteoarthritis drug (DMOAD) that can effectively manage osteoarthritis has yet to be identified. The current study was undertaken to explore the potential of injectable, in situ forming implants to create depots that support the sustained release of punicalagin, a promising DMOAD. In vitro experiments demonstrated punicalagin's ability to suppress production of interleukin-1β and prostaglandin E2, confirming its chondroprotective properties. Regarding the entrapment of punicalagin, it was demonstrated by LC-MS/MS to be stable within PLGA in situ forming implants for several weeks and capable of inhibiting collagenase upon release. In vitro punicalagin release kinetics were tunable through variation of solvent, PLGA lactide:glycolide ratio, and polymer concentration, and an optimized formulation supported release for approximately 90 days. The injection force of this formulation steadily increased with plunger advancement and higher rates of advancement were associated with greater forces. Although the optimal formulation was highly cytotoxic to primary chondrocytes if cells were exposed immediately or shortly after implant formation, upwards of 70 % survival was achieved when the implants were first allowed to undergo a 24-72 h period of phase inversion prior to cell exposure. This study demonstrates a PLGA-based in situ forming implant for the controlled release of punicalagin. With modification to address cytotoxicity, such an implant may be suitable as an intra-articular therapy for OA.

Medicinal plants and their secondary metabolites in alleviating knee osteoarthritis: A systematic review

BACKGROUND

With the increasing ages of the general population, the incidence of knee osteoarthritis (KOA) is also rising, and KOA has become a major health problem worldwide. Recently, medicinal plants and their secondary metabolites have gained interest due to their activity in treating KOA. In this paper, a comprehensive systematic review of the literature was performed concerning the effects of medicinal plant extracts and natural compounds against KOA in recent years. The related molecular pathways of natural compounds against KOA were summarized, and the possible crosstalk among components in chondrocytes was discussed to propose possible solutions for the current situation of treating KOA.

PURPOSE

This review focused on the molecular mechanisms by which medicinal plants and their secondary metabolites act against KOA.

METHODS

Literature searches were performed in the PUBMED, Embase, Science Direct, and Web of Science databases for a 10-year period from 2011 to 2022 with the search terms "medicinal plants," "bioactive compounds," "natural products," "phytochemical," "knee osteoarthritis," "knee joint osteoarthritis," "knee osteoarthritis," "osteoarthritis of the knee," and "osteoarthritis of knee joint."

RESULTS

According to the results, substantial plant extracts and secondary metabolites show a positive effect in fighting KOA. Plant extracts and their secondary metabolites can affect the diagnostic and prognostic biomarkers of KOA. Natural products inhibit the expression of MMP1, MMP3, MMP19, syndecan IV, ADAMTS-4, ADAMTS-5, iNOS, COX-2, collagenases, IL-6, IL-1β, and TNF-α in vitro and in vivo and . Cytokines also upregulate the expression of collagen II and aggrecan. The main signaling pathways affected by the extracts and isolated compounds include AMPK, SIRT, NLRP3, MAPKs, PI3K/AKT, mTOR, NF-κB, WNT/β-catenin, JAK/STAT3, and NRF2, as well as the cell death modes apoptosis, autophagy, pyroptosis, and ferroptosis.

CONCLUSION

The role of secondary metabolites in different signaling pathways supplies a better understanding of their potential to develop further curative options for KOA.

Do Pomegranate Hydrolyzable Tannins and Their Derived Metabolites Provide Relief in Osteoarthritis? Findings from a Scoping Review

Osteoarthritis (OA) is the most common form of arthritis affecting both the elderly and the middle-aged population. Although various therapeutics have been developed to arrest the structural deterioration of cartilage, the current treatments are limited to delay the progress of OA clinically. Therefore, it is pivotal to study new therapeutic agents for chondroprotection and the prevention of cartilage degeneration. Hydrolyzable tannin (HT)-containing foods aroused considerable interest in recent years for their relevant anti-inflammatory effects. The focus of this scoping review is to provide an overview of the evidence of the therapeutic potential of HTs and their metabolites in preventing or alleviating the course of OA. A broad search of PubMed and Scopus databases on this topic resulted in 156 articles. After the exclusion of reviews and not relevant records, 31 articles were retrieved. Although only some papers did not consider the biotransformation of HTs, most recent studies also have investigated the effect of HT metabolites. Further larger clinical trials, with an in-deep analysis of HT metabolization, are still needed to unravel the potential benefits of these compounds in OA, paving the way towards the development of a dietary strategy for the improvement of pro-inflammatory cytokine-induced chondrocyte dysfunctions and injuries.

Systematic review of the effects of pomegranate (Punica granatum) on osteoarthritis

Background: Considering limitations of the established osteoarthritis (OA) medications, attention to adjuvant and complementary treatments has increased in OA individuals. Recent investigations have reported advantages of pomegranate in OA and indicate that pomegranate can be a therapeutic option; nevertheless, no systematic review exists regarding OA and pomegranate. Therefore, we systematically studied accessible researches regarding pomegranate and OA in human, animal, and in vitro models and likely mechanistic pathways. Methods: Present systematic review study was recorded on the international prospective register of systematic reviews database. Electronic databases (Scopus, PubMed, Embase, WOS, ProQuest) and search engine Google Scholar were searched until February 2021. Search alerts were turned on to recognize papers published following the primary search. Two investigators independently searched using MESH and non-MESH words in title, abstract, and keywords. Inclusion criteria were related clinical, animal, and in vitro studies published in any language as a full text. Exclusion criteria were reviews, book chapters, conference abstracts, and articles regarding pomegranate in health problems other than OA. Hand searching was used to check the references or citations of eligible papers and grey literature (theses etc.) to find potential researches. Results: Twenty-three articles were included in our systematic review. Human, animal, and in vitro researches demonstrated favorable properties of pomegranate in improving clinical features and reducing inflammatory, oxidative stress, and apoptosis markers in OA. Conclusion: Present paper provides convincing evidence about the efficacy of pomegranate in OA and gives a justification for the importance of additional clinical studies.

Punicalagin ameliorates collagen-induced arthritis by downregulating M1 macrophage and pyroptosis via NF-κB signaling pathway

Rheumatoid arthritis (RA) is a chronic inflammatory disease that eventually leads to disability. Inflammatory cell infiltration, severe joint breaking and systemic bone loss are the main clinical symptoms. In this study, we established a collagen-induced arthritis (CIA) model and found a large number of M1 macrophages and pyroptosis, which are important sources of proinflammatory cytokines. Punicalagin (PUN) is an active substance extracted from pomegranate peel. We found that it inhibited joint inflammation, cartilage damage and systemic bone destruction in CIA mice. PUN effectively alleviated the high expression of inflammatory cytokines in synovial tissue in vivo. PUN treatment shifted macrophages from the M1 phenotype to the M2 phenotype after stimulation with lipopolysaccharide (LPS) and interferon (IFN)-γ. The expression of inducible nitric oxide synthase (iNOS) and other proinflammatory cytokines released by M1 macrophages was decreased in the PUN treatment group. However, simultaneously, the expression of markers of anti-inflammatory M2 macrophages, such as arginase (Arg)-1 and interleukin (IL)-10, was increased. In addition, PUN treatment attenuated pyroptosis by downregulating the expression of NLRP3 and caspase-1, thereby preventing inflammatory cell death resulting from the release of IL-1β and IL-18. Mechanistically, PUN inhibited the activation of receptor activators of the nuclear factor-κB (NF-κB) signaling pathway, which contributes to M1 polarization and pyroptosis of macrophages. We concluded that PUN ameliorated pathological inflammation by inhibiting M1 phenotype polarization and pyroptosis and has great potential as a therapeutic treatment for human RA.

Punicalagin Inhibited Inflammation and Migration of Fibroblast-Like Synoviocytes Through NF-κB Pathway in the Experimental Study of Rheumatoid Arthritis

Background

The aggressive phenotype of fibroblast-like synoviocytes (FLSs) is essential in the synovitis and bone destruction in rheumatoid arthritis (RA). Punicalagin is a natural polyphenol extracted in pomegranate juice, which possesses antioxidant, anti-inflammatory and anti-tumor properties suggesting it may be a potent drug for RA therapy. However, there is paucity of information on its effect in RA.

Objective

To investigate the effects of punicalagin on synovial inflammation and bone destruction in RA.

Methods

FLSs were isolated from synovial tissue of RA patients. The mRNA levels were evaluated by quantitative real-time PCR. Western blot was used for protein level measurements. The secretion of pro-inflammatory cytokines and metalloproteinases (MMPs) was detected by ELISA assays. Edu staining assays were carried out to investigate the proliferation of FLSs. Cell migration was assessed by Boyden chambers, wound scratch assays and F-actin staining in vitro. The intracellular translocation of nuclear factor kappa B (NF-κB) was investigated using immunofluorescence. The effects of punicalagin in vivo were measured by using collagen-induced arthritis (CIA) mice.

Results

Punicalagin treatments significantly reduced the TNF-α induced expressions of pro-inflammatory cytokines (IL-1β, IL-6, IL-8 and IL-17A) and MMPs (MMP-1 and MMP-13) of RA FLSs. Punicalagin also suppressed the proliferation and migration of RA FLSs. Moreover, punicalagin (50mg/kg/d) alleviated arthritis severity and bone destruction, and decreased serum IL-6 and TNF-α in CIA mice. Further mechanism studies indicated that punicalagin blocked NF-κB activation via suppressing phosphorylation of IKK and IkBα, and preventing the translocation of 65.

Conclusion

Our findings suggested that punicalagin might be one of natural therapeutic compounds for relieving RA progress via suppressing FLSs inflammation and migration through modulating NF-κB pathways.