Esculetin inhibits cartilage resorption induced by interleukin 1alpha in combination with oncostatin M

Novel missense ACAN gene variants linked to familial osteochondritis dissecans cluster in the C-terminal globular domain of aggrecan

The cartilage aggrecan proteoglycan is crucial for both skeletal growth and articular cartilage function. A number of aggrecan (ACAN) gene variants have been linked to skeletal disorders, ranging from short stature to severe chondrodyplasias. Osteochondritis dissecans is a disorder where articular cartilage and subchondral bone fragments come loose from the articular surface. We previously reported a missense ACAN variant linked to familial osteochondritis dissecans, with short stature and early onset osteoarthritis, and now describe three novel ACAN gene variants from additional families with this disorder. Like the previously described variant, these are autosomal dominant missense variants, resulting in single amino acid residue substitutions in the C-type lectin repeat of the aggrecan G3 domain. Functional studies showed that neither recombinant variant proteins, nor full-length variant aggrecan proteoglycan from heterozygous patient cartilage, were secreted to the same level as wild-type aggrecan. The variant proteins also showed decreased binding to known cartilage extracellular matrix ligands. Mapping these and other ACAN variants linked to hereditary skeletal disorders showed a clustering of osteochondritis dissecans-linked variants to the G3 domain. Taken together, this supports a link between missense ACAN variants affecting the aggrecan G3 domain and hereditary osteochondritis dissecans.

Artemisia scoparia and Metabolic Health: Untapped Potential of an Ancient Remedy for Modern Use

Botanicals have a long history of medicinal use for a multitude of ailments, and many modern pharmaceuticals were originally isolated from plants or derived from phytochemicals. Among these, artemisinin, first isolated from Artemisia annua, is the foundation for standard anti-malarial therapies. Plants of the genus Artemisia are among the most common herbal remedies across Asia and Central Europe. The species Artemisia scoparia (SCOPA) is widely used in traditional folk medicine for various liver diseases and inflammatory conditions, as well as for infections, fever, pain, cancer, and diabetes. Modern in vivo and in vitro studies have now investigated SCOPA's effects on these pathologies and its ability to mitigate hepatotoxicity, oxidative stress, obesity, diabetes, and other disease states. This review focuses on the effects of SCOPA that are particularly relevant to metabolic health. Indeed, in recent years, an ethanolic extract of SCOPA has been shown to enhance differentiation of cultured adipocytes and to share some properties of thiazolidinediones (TZDs), a class of insulin-sensitizing agonists of the adipogenic transcription factor PPARγ. In a mouse model of diet-induced obesity, SCOPA diet supplementation lowered fasting insulin and glucose levels, while inducing metabolically favorable changes in adipose tissue and liver. These observations are consistent with many lines of evidence from various tissues and cell types known to contribute to metabolic homeostasis, including immune cells, hepatocytes, and pancreatic beta-cells. Compounds belonging to several classes of phytochemicals have been implicated in these effects, and we provide an overview of these bioactives. The ongoing global epidemics of obesity and metabolic disease clearly require novel therapeutic approaches. While the mechanisms involved in SCOPA's effects on metabolic, anti-inflammatory, and oxidative stress pathways are not fully characterized, current data support further investigation of this plant and its bioactives as potential therapeutic agents in obesity-related metabolic dysfunction and many other conditions.

Scaffold-based Screening and Molecular Dynamics Simulation Study to Identify Two Structurally Related Phenolic Compounds as Potent MMP1 Inhibitors

BACKGROUND

Matrix metalloproteinase 1 are zinc-dependent endopeptidases responsible for the controlled breakdown of the extracellular matrix resulting in the maintenance of homeostasis. Dysregulation of MMP1 leads to the progression of various pathological conditions like cancer, rheumatoid arthritis, cardiovascular disease, skin damage and fibrotic disorder. Thus, MMP1 inhibition is the potential drug target of many synthetic MMP1 inhibitors but lack of substrate specificity hinders their clinical applicability. Hence, inhibitors from natural products have gained widespread attention.

OBJECTIVE

The present study attempts screening of novel MMP1 inhibitors from the ZINC database based on experimentally reported natural inhibitors of MMP1 as a scaffold.

METHODS

Molecular docking study was performed with 19 experimentally reported natural inhibitors spanning across nine different classes followed by virtual screening using the selected compounds. The selected compounds were subjected to molecular dynamics simulation.

RESULTS

Twenty compounds were screened with a cut-off of -9.0 kcal/mol of predicted free energy of binding, which further converged to 6 hits after docking studies. After comparing the docking result of 6 screened hits, two best compounds were selected. ZINC02436922 had the best interaction with six hydrogen bond formation to a relatively confined region in the S1'site of MMP1 and -10.01 kcal/mol of predicted free energy of binding. ZINC03075557 was the secondbest compound with -9.57 kcal/mol predicted binding free energy. Molecular dynamics simulation of ZINC02436922 and ZINC03075557 corroborates docking study.

CONCLUSION

This study indicated phenolic compounds ZINC02436922 and ZINC03075557 as potential MMP1 inhibitors.

Esculetin reduces leukotriene B4 level in plasma of rats with adjuvant-induced arthritis

Objectives

Esculetin (6,7-dihydroxycoumarin) is a natural coumarin with anti-oxidant, anti-inflammatory and anti-nociceptive activity. It acts as a potent inhibitor of lipoxygenases (5-LOX and 12-LOX) and decreases the production of matrix metalloproteinases (MMP-1, MMP-3 and MMP-9). Because both inhibition of lipoxygenases and inhibition of matrix metalloproteinases are effective strategies in the treatment of rheumatoid arthritis, we investigated whether esculetin may be effective in adjuvant-induced arthritis in rats.

Material and methods

The study was performed on male Lewis rats, in the adjuvant-induced arthritis model. Rats were divided into two groups: control (treated with 1% methylcellulose) and experimental (treated with esculetin – 10 mg/kg ip.). The tested compound was administered for 5 consecutive days starting on the 21^st day after induction of arthritis. Each group consisted of 7 animals. After 5 days of treatment, rats were anesthetized. The concentration of leukotriene B4 (LTB4) in plasma was determined by a competitive enzyme immunoassay.

Results

The LTB4 level in plasma of rats with adjuvant-induced arthritis is increased in comparison to rats without inflammation (362 ±34 vs. 274 ±15 pg/ml, p < 0.01, respectively). Five-day treatment with esculetin in adjuvant-induced arthritis rats decreases the LTB4 level to a level comparable with rats without inflammation (284 ±23 pg/ml, p < 0.01).

Conclusions

LTB4 is the most potent chemotactic agent influencing neutrophil migration into the joint. It is known that its level in serum of patients with active rheumatoid arthritis is increased and correlates with disease severity. Some other lipoxygenase inhibitors have already been tested as potential drug candidates in clinical and preclinical trials for rheumatoid arthritis (Zileuton, PF-4191834). Because esculetin decreases the LTB4 level in plasma of rats in adjuvant-induced arthritis, it may also be considered as an attractive drug candidate for patients with rheumatoid arthritis.

Age-dependent effects of esculetin on mood-related behavior and cognition from stressed mice are associated with restoring brain antioxidant status

Dietary antioxidants might exert an important role in the aging process by relieving oxidative damage, a likely cause of age-associated brain dysfunctions. This study aims to investigate the influence of esculetin (6,7-dihydroxycoumarin), a naturally occurring antioxidant in the diet, on mood-related behaviors and cognitive function and its relation with age and brain oxidative damage. Behavioral tests were employed in 11-, 17- and 22-month-old male C57BL/6J mice upon an oral 35day-esculetin treatment (25mg/kg). Activity of antioxidant enzymes, GSH and GSSG levels, GSH/GSSG ratio, and mitochondrial function were analyzed in brain cortex at the end of treatment in order to assess the oxidative status related to mouse behavior. Esculetin treatment attenuated the increased immobility time and enhanced the diminished climbing time in the forced swim task elicited by acute restraint stress (ARS) in the 11- and 17-month-old mice versus their counterpart controls. Furthermore, ARS caused an impairment of contextual memory in the step-through passive avoidance both in mature adult and aged mice which was partially reversed by esculetin only in the 11-month-old mice. Esculetin was effective to prevent the ARS-induced oxidative stress mostly in mature adult mice by restoring antioxidant enzyme activities, augmenting the GSH/GSSG ratio and increasing cytochrome c oxidase (COX) activity in cortex. Modulation of the mood-related behavior and cognitive function upon esculetin treatment in a mouse model of ARS depends on age and is partly due to the enhancement of redox status and levels of COX activity in cortex.

The in vivo effect of esculetin ointment and esculetin-mixed Zyderm for Zyderm

BACKGROUND

Injectable collagen is often used for treatment of wrinkles or scars in cosmetic surgery. However, it is degraded within a short period after subcutaneous injection. The authors aimed to achieve a long-lasting effect of the filler with a new collagenase inhibitor, esculetin (6,7-dihydroxy-2H-chromen-2-one).

METHOD

Nude mice were divided into two study groups and a control group (35 mg cattle collagen): (1) those implanted with Zyderm 0.3 g subcutaneously into the dorsal region followed by daily topical application of 5% esculetin ointment (0.5 g/day) to the skin of the implanted area (the 5% esculetin ointment group), and (2) those implanted with a mixture of Zyderm 0.3 g and esculetin (1 to 4 mM) (the esculetin-mixed Zyderm groups). In each group, Zyderm was removed at different time points to measure the wet weight and hydroxyproline level. Furthermore, each removed Zyderm specimen was sectioned for histologic examination with Azan staining and immunostaining.

RESULTS

In the esculetin ointment group and the 2 mM esculetin-mixed Zyderm group, the hydroxyproline levels at 30, 60, and 90 days were significantly higher than those in the control group, suggesting that esculetin suppresses the biodegradation of Zyderm. There was no significant difference in hydroxyproline level between the esculetin ointment group and the 2 mM esculetin-mixed Zyderm group; biodegradation occurred to a similar extent with either method of application.

CONCLUSIONS

An atelocollagen implant is used as a safe and effective scaffold material for tissue regeneration. Future applications of the present study are expected.

Analysis of ADAMTS4 and MT4-MMP indicates that both are involved in aggrecanolysis in interleukin-1-treated bovine cartilage

OBJECTIVE

To investigate the mechanism of aggrecanolysis in interleukin-1 (IL-1)-treated cartilage tissue by examining the time course of aggrecan cleavages and the tissue and medium content of membrane type 4-matrix metalloproteinases (MT4-MMP) and a disintegrin and metalloproteinase with thrombospondin type I motifs (ADAMTS)4.

METHODS

Articular cartilage explants were harvested from newborn bovine femoropatellar groove. The effects of IL-1 treatment with or without aggrecanase blockade were investigated by Western analysis of aggrecan fragment generation, ADAMTS4 species (p68 and p53), and MT4-MMP, as well as by realtime PCR (polymerase chain reaction) for ADAMTS4 and 5. Aggrecanase was blocked with mannosamine (ManN), an inhibitor of glycosylphosphatidylinositol anchor synthesis, and esculetin (EST), an inhibitor of MMP-1, MMP-3, and MMP-13 gene expression.

RESULTS

IL-1 treatment caused a major increase in MT4-MMP abundance in the tissue and medium. ADAMTS4 (p68) was abundant in fresh cartilage and this was retained in the tissue in untreated cartilage. IL-1 treatment for 6 days caused a marked loss of p68 from the cartilage and the appearance of p53 in the medium. Addition of either 1.35 mM ManN or 31-500 microM EST blocked IL-1-mediated aggrecanolysis and this was accompanied by nearly complete inhibition of the MT4-MMP increase, the p68 loss and the formation of p53. IL-1 treatment increased mRNA abundance for ADAMTS4 ( approximately 3-fold) and ADAMTS5 ( approximately 10-fold) but this was not accompanied by a marked change in enzyme protein abundance.

CONCLUSION

These studies support a central role for MT4-MMP in IL-1-induced cartilage aggrecanolysis and are consistent with the identification of p68 as the aggrecanase that cleaves within the CS2 domain, and of p53 as the aggrecanase that generates G1-NITEGE. Since the induction by IL-1 was not accompanied by marked changes in total ADAMTS4 protein, but rather in partial conversion of p68 to p53 and release of both from the tissue, we conclude that aggrecanolysis in this model system results from MT4-MMP-mediated processing of a resident pool of ADAMTS4 and release of the p68 and p53 from their normal association with the cell surface.

Oncostatin M in the anti-inflammatory response

Oncostatin M (OM) is a pleiotropic cytokine of the interleukin 6 family, whose in vivo properties and physiological function remain in dispute and poorly defined. These in vivo studies strongly suggest that OM is anabolic, promoting wound healing and bone formation, and anti-inflammatory. In models of inflammation OM is produced late in the cytokine response and protects from lipopolysaccharide (LPS)-induced toxicities, promoting the re-establishment of homoeostasis by cooperating with proinflammatory cytokines and acute phase molecules to alter and attenuate the inflammatory response. Administration of OM inhibited bacterial LPS-induced production of tumour necrosis factor alpha and septic lethality in a dose dependent manner. Consistent with these findings, in animal models of chronic inflammatory disease OM potently suppressed inflammation and tissue destruction in murine models of rheumatoid arthritis and multiple sclerosis. T cell function and antibody production were not impaired by OM treatment. Taken together, these data indicate that the activities of this cytokine in vivo are anti-inflammatory without concordant immunosuppression.

The clinical potential of matrix metalloproteinase inhibitors in the rheumatic disorders

Rheumatoid arthritis (RA) and osteoarthritis are chronic diseases that result in cartilage degradation and loss of joint function. Currently available drugs are predominantly directed towards the control of pain and/or the inflammation associated with joint synovitis but they do little to reduce joint destruction. In the future, it will be important to have drugs that prevent the structural damage caused by bone and cartilage breakdown. In this review, we will outline the structure and function of cartilage and the key features of matrix metalloproteinases (MMPs), enzymes involved in joint destruction. We will present evidence for the role of MMPs in RA and osteoarthritis, and describe the potential of synthetic inhibitors to control MMP activity and so prevent joint destruction. MMPs are able to cleave all components of the cartilage matrix. Regulation of MMPs is aberrant in osteoarthritis and RA, and MMPs have been implicated in the collagen breakdown that contributes to joint destruction in these diseases. Synthetic MMP inhibitors have been developed. In animal models of osteoarthritis and/or RA, these agents have shown chondroprotective effects. However, results from clinical trials in RA have been equivocal, with some studies being terminated because of lack of efficacy or safety concerns. Nevertheless, this approach remains promising. Increased understanding of the structure, regulation and function of individual MMPs may lead to more effective strategies, and approaches aimed at multiple steps of the pathogenesis of arthritis may be needed to break the chronic cycle of joint destruction.