The chondroprotective effect of diosmin on human articular chondrocytes under oxidative stress

Aberrant methylation and expression of TNXB promote chondrocyte apoptosis and extracullar matrix degradation in hemophilic arthropathy via AKT signaling

Recurrent joint bleeding in hemophilia patients frequently causes hemophilic arthropathy (HA). Drastic degradation of cartilage is a major characteristic of HA, but its pathological mechanisms has not yet been clarified. In HA cartilages, we found server matrix degradation and increased expression of DNA methyltransferase proteins. We thus performed genome-wide DNA methylation analysis on human HA (N=5) and osteoarthritis (OA) (N=5) articular cartilages, and identified 1228 differentially methylated regions (DMRs) associated with HA. Functional enrichment analyses revealed the association between DMR genes (DMGs) and extracellular matrix (ECM) organization. Among these DMGs, Tenascin XB (TNXB) expression was down-regulated in human and mouse HA cartilages. The loss of Tnxb in F8-/- mouse cartilage provided a disease-promoting role in HA by augmenting cartilage degeneration and subchondral bone loss. Tnxb knockdown also promoted chondrocyte apoptosis and inhibited phosphorylation of AKT. Importantly, AKT agonist showed chondroprotective effects following Tnxb knockdown. Together, our findings indicate that exposure of cartilage to blood leads to alterations in DNA methylation, which is functionally related to ECM homeostasis, and further demonstrate a critical role of TNXB in HA cartilage degeneration by activating AKT signaling. These mechanistic insights allow development of potentially new strategies for HA cartilage protection.

Comprehensive and critical view on the anti-inflammatory and immunomodulatory role of natural phenolic antioxidants

The immune response encompasses innate and adaptive immunity, each with distinct and specific activities. The innate immune system is constituted by phagocytic cells, macrophages, monocytes and neutrophils, the cascade system, and different classes of receptors such as toll-like receptors that are exploited by the innate immune cells. The adaptive immune system is antigen-specific, encompassing memory lymphocytes and the corresponding specific receptors. Inflammation is understood as an activation of different signaling pathways such as toll-like receptors or nuclear factor kappa-light-chain-enhancer of activated B cells, with an increase in nitric oxide, inflammatory cytokines and chemokines. Increased oxidative stress has been identified as main source of chronic inflammation. Phenolic antioxidants modulate the activities of lymphocytes and macrophages by impacting cytokines and nitric oxide release, exerting anti-inflammatory effect. The nuclear-factor kappa-light-chain-enhancer of activated B cells signaling pathway and the mitogen-activated protein kinase pathway are targeted, alongside an increase in nuclear factor erythroid 2-related factor mediated antioxidant response, triggering the activity of antioxidant enzymes. The inhibitive potential on phospholipase A2, cyclooxygenase and lipoxygenase in the arachidonic acid pathway, and the subsequent reduction in prostaglandin and leukotriene generation, reveals the potential of phenolics as inflammation antagonists. The immunomodulative potential encompasses the capacity to interfere with proinflammatory cytokine synthesis and with the expression of the corresponding genes. A diet rich in antioxidants can result in prevention of inflammation-related pathologies. More investigations are necessary to establish the role of these antioxidants in therapy. The appropriate delivery system and the prooxidant effects exhibited at large doses, or in the presence of heavy metal cations should be regarded.

Diosmin ameliorates LPS-induced depression-like behaviors in mice: Inhibition of inflammation and oxidative stress in the prefrontal cortex

Diosmin is a flavone glycoside with a confirmed therapeutic effectiveness on the chronic venous disorders. In this paper, the classical mouse depression model induced by LPS was established to explore the effect of Diosmin on depression. Firstly, we found that Diosmin could inhibit the inflammation and neuronal damage in the prefrontal cortex (PFC) of mice, and thus alleviating the LPS-induced depressive-like behaviors. Specifically, Diosmin treatment significantly suppressed the secretion of pro-inflammatory cytokines (TNF-α, IL-6 and IL-1β), reduced the activation of microglia, and inhibited the expression of NLRP3 inflammasome and its downstream effector caspase-1 in both PFC of mice and BV2 microglial cells exposed to LPS. Then, we demonstrated that pretreatment with Diosmin dramatically suppressed the LPS-induced oxidative stress in the PFC of mice, manifested in the decrease of reactive oxygen species and malondialdehyde while increase of catalase activity. Consistently, Diosmin also alleviated the oxidative stress in BV2 cells exposed to LPS. Finally, we confirmed that Diosmin effectively suppressed the activation of NF-κB signaling pathway in the PFC of LPS-treated mice. Further in vitro experiments also verified that Diosmin could prevent the p65 transposition to nucleus in LPS-treated BV2 cells, suggesting that the antidepressant effects of Diosmin are partially mediated by blocking of NF-κB signaling. Taken together, this study proposes the potential antidepressant effect of Diosmin, which provides useful support to the development of new therapies for depression.

Polyherbal formulation PL02 alleviates pain, inflammation, and subchondral bone deterioration in an osteoarthritis rodent model

Introduction

Osteoarthritis (OA) is a debilitating disease with significant personal and socioeconomic burdens worldwide.

Methods

To address this, we developed a multitargeted formulation called PL02, which includes standardized extracts of Rosa canina L, Hippophae rhamnoides, and collagen peptide. We tested the pharmacological efficacy of PL02 in a rodent model of OA induced by Monosodium iodoacetate (MIA).

Results

Our results demonstrate that oral administration of PL02 has antioxidant effects by down-regulating NOS, reduces pain-related behavior, and mitigates inflammation by inhibiting IL-1b and TNF-α production, as well as downregulating CGRP1 and COX-II. PL02 also exhibits anti-catabolic and chondroprotective activity by significantly downregulating MMP13 and upregulating BCL2. Additionally, PL02 demonstrates chondrogenic activity by significantly upregulating SOX-9 (a master regulator of chondrogenesis), Coll-I, and aggrecan, which are major components of articular cartilage. Furthermore, PL02 prevents microarchitectural deterioration of subchondral bone.

Conclusion

Overall, PL02 is an orally active, multi-targeted therapy that not only alleviates pain and inflammation but also effectively halts cartilage and subchondral bone deterioration. It represents a safe and promising candidate for the treatment and management of OA.

Evaluation and Optimization of Quality Based on the Physicochemical Characteristics and Metabolites Changes of Qingpi during Storage

Qingpi, the dried immature pericarp of Citrus reticulata Blanco, is a commonly used medicinal food with some health-promoting benefits. In general, it is essential that Qingpi be stored for a period of time, but there are no reports about the number of storage years needed to obtain the best quality of Qingpi. Our aim was to determine the best storage time of Qingpi by studying the physicochemical properties and metabolite changes in product stored from 1 to 5 years. As a result, the color of Qingpi became darker during storage. Both the levels of three flavonoids (hesperidin, nobiletin, and tangeretin) and total flavonoids (TFs) and the antioxidant activity decreased during storage and the total phenolics (TPs) content fluctuated during storage. Cluster analysis was performed on the color parameters measured using a color difference meter, revealing that the color of Qingpi differed before and after 3 years of storage. A total of 9 special differential metabolites were identified that could be used to distinguish the storage years of Qingpi. This is the first study to report the quality changes of Qingpi during storage. The optimized results of the quality evaluation indicated that Qingpi should be stored for no more than 3 years.

Flavonoids: Antiplatelet Effect as Inhibitors of COX-1

Flavonoids are compounds with a benzopyranic structure that exhibits multiple pharmacological activities. They are known for their venotonic activity, but their mechanism of action remains unclear. It is thought that, as this mechanism is mediated by prostaglandins, these compounds may interfere with the arachidonic acid (AA) cascade. These assays are designed to measure the antiplatelet aggregation capacity of quercetin, rutin, diosmetin, diosmin, and hidrosmin, as well as to evaluate a potential structure−activity ratio. In this paper, several studies on platelet aggregation at different concentrations (from 0.33 mM to 1.5 mM) of different flavone compounds are conducted, measuring platelet aggregation by impedance aggregometry, and the cyclooxygenase (COX) activity by metabolites generated, including the activity of the pure recombinant enzyme in the presence of these polyphenols. The results obtained showed that quercetin and diosmetin aglycones have a greater antiplatelet effect and inhibit the COX enzyme activity to a greater extent than their heterosides; however, the fact that greater inhibition of the pure recombinant enzyme was achieved by heterosides suggests that these compounds may have difficulty in crossing biological membranes. In any case, in view of the results obtained, it can be concluded that flavonoids could be useful as coadjuvants in the treatment of cardiovascular pathologies.

Chondrocyte Aging: The Molecular Determinants and Therapeutic Opportunities

Osteoarthritis (OA) is a joint degenerative disease that is an exceedingly common problem associated with aging. Aging is the principal risk factor for OA, but damage-related physiopathology of articular chondrocytes probably drives the mechanisms of joint degeneration by a progressive decline in the homeostatic and regenerative capacity of cells. Cellular aging is the manifestation of a complex interplay of cellular and molecular pathways underpinned by transcriptional, translational, and epigenetic mechanisms and niche factors, and unraveling this complexity will improve our understanding of underlying molecular changes that affect the ability of the articular cartilage to maintain or regenerate itself. This insight is imperative for developing new cell and drug therapies for OA disease that will target the specific causes of age-related functional decline. This review explores the key age-related changes within articular chondrocytes and discusses the molecular mechanisms that are commonly perturbed as cartilage ages and degenerates. Current efforts and emerging potential therapies in treating OA that are being employed to halt or decelerate the aging processes are also discussed.

Glabridin inhibits osteoarthritis development by protecting chondrocytes against oxidative stress, apoptosis and promoting mTOR mediated autophagy

Osteoarthritis (OA) is a common chronic degenerative disease that affects the elderly. Thus far, no pharmacological therapy approved by regulators has shown a convincing effect on OA. Glabridin, a small molecule, is a well-known and powerful natural antioxidant, which has a strong scavenging effect on free radicals. This study attempted to explore the role and underlying mechanisms of Glabridin on OA both in vitro and in vivo. In the in vitro study, Glabridin was found to increase the expression levels of extracellular matrix (ECM) related genes, Collagen II, Aggrecan (ACAN), SRY-box 9 (SOX9) and proteoglycan 4 (PRG4). Moreover, Glabridin was observed to significantly reduce the level of oxidative stress in OA chondrocytes while effectively reducing the apoptosis of chondrocytes. Glabridin was also found to significantly increase the autophagy of human OA chondrocytes. During the in vivo study, intraarticular injection of Glabridin was observed to alleviate OA progression and protect chondrocytes against apoptosis following anterior cruciate ligament transection (ACLT) in rats. Furthermore, the mammalian target of rapamycin (mTOR) mediated autophagy was identified as one of the potential mediators of Glabridin activity. Overall, Glabridin protects articular cartilage from damage in rats with OA by protecting chondrocytes against oxidative stress, apoptosis and promoting mTOR mediated autophagy.

Silymarin modulates catabolic cytokine expression through Sirt1 and SOX9 in human articular chondrocytes

Background

Silymarin (SMN), a polyphenolic flavonoid, is involved in multiple bioactive functions including anti-inflammation. Pretreatment with SMN demonstrated chondroprotection against tumour necrosis factor-alpha (TNF-α) stimulation in a chondrocyte cell line. However, pre- and posttreatment with phytochemicals have varying effects on osteoarthritis (OA) chondrocytes, and the therapeutic potential of SMN after catabolic cytokine stimulation is not fully elucidated.

Methods

The cytotoxicity of SMN (12.5, 25, 50 and 100 μM) was evaluated in human primary chondrocytes. The chondrocytes were supplemented with SMN (25 and 50 μM) after interleukin-1beta (IL-1β) stimulation. The mRNA expression and protein production of catabolic/anabolic cytokines as well as extracellular matrix (ECM) components were evaluated.

Results

High-dose SMN (100 μM) impaired the mitochondrial activity in chondrocytes, and 50 μM SMN further caused cell death in IL-1β-stimulated cells. The addition of 25 μM SMN ameliorated cell senescence; downregulated the catabolic genes of inducible nitric oxide synthase, IL-1β, TNF-α, matrix metalloproteinase-3 (MMP-3), MMP-9 and MMP-13; upregulated the anabolic genes of tissue inhibitor of metalloproteinase-1 (TIMP-1) and collagen type II alpha 1; and restored the expression of chondrogenic phenotype genes SOX9 and sirtuin-1 (Sirt1). In addition, the production of IL-1β, MMP-3 and MMP-9 decreased with an increase in TIMP-1 secretion. However, the mRNA levels of IL-6, IL-8 and IL-10 and protein production remained high. The addition of nicotinamide, a Sirt1 inhibitor, downregulated SOX9 and attenuated the therapeutic effects of SMN on IL-1β-stimulated chondrocytes.

Conclusion

SMN regulates the chondrocyte phenotype through Sirt1 and SOX9 to improve ECM homeostasis and may serve as a complementary therapy for early-stage knee OA.

Evaluation of the post-treatment anti-inflammatory capacity of osteoarthritic chondrocytes: An in vitro study using baicalein

INTRODUCTION

Targeting inflammatory cascades is considered a promising way to prevent knee osteoarthritis (OA) progression. In terms of down-regulating the expression of inducible nitric oxide synthase (iNOS), interleukin (IL)-6, and matrix metalloproteinases (MMPs), pre-treatment with the flavonoid baicalein reportedly protects articular chondrocytes against the cytotoxicity of IL-1β. However, the benefits of post-treatment baicalein on osteoarthritic chondrocytes are not fully elucidated.

METHODS

In this study, primary human chondrocytes were stimulated with IL-1β prior to baicalein application to evaluate the therapeutic effect of post-treatment.

RESULTS

Post-treatment baicalein alleviated cell death and partially restored mitochondrial viability, while the senescence-associated secretory phenotype was not improved in IL-1β-stimulated chondrocytes. Post-treatment baicalein down-regulated the expressions of IL-1β, tumor necrosis factor-alpha, MMP-3, MMP-9, and MMP-13 mRNA as well as the protein production in stimulated cells. Even so, the levels of these factors were relative higher than those in un-treated chondrocytes. Moreover, iNOS, IL-6, IL-8, and COL1A1 expressions were consistently high, and IL-10 protein synthesis steadily increased in IL-1β-treated chondrocytes under baicalein treated status. Moreover, Western blot analyses showed that post-treatment baicalein suppressed nuclear factor kappa-light-chain-enhancer of activated B cells and p50 production while downstream cyclooxygenase-2 was still highly expressed.

CONCLUSION

Baicalein post-treatment to osteoarthritic chondrocytes had a minor benefit to the homeostasis of cartilaginous extracellular matrix.

Metabolism and pharmacological activities of the natural health-benefiting compound diosmin

Diosmin is a famous natural flavonoid for treating chronic venous insufficiency and varicose veins.