Fibrates as therapy for osteoarthritis and rheumatoid arthritis? A systematic review

NAPE-PLD regulates specific baseline affective behaviors but is dispensable for inflammatory hyperalgesia

N-acyl-ethanolamine (NAEs) serve as key endogenous lipid mediators as revealed by manipulation of fatty acid amide hydrolase (FAAH), the primary enzyme responsible for metabolizing NAEs. Preclinical studies focused on FAAH or NAE receptors indicate an important role for NAE signaling in nociception and affective behaviors. However, there is limited information on the role of NAE biosynthesis in these same behavioral paradigms. Biosynthesis of NAEs has been attributed largely to the enzyme N-acylphosphatidylethanolamine Phospholipase D (NAPE-PLD), one of three pathways capable of producing these bioactive lipids in the brain. In this report, we demonstrate that Nape-pld knockout (KO) mice displayed reduced sucrose preference and consumption, but other baseline anxiety-like or depression-like behaviors were unaltered. Additionally, we observed sex-dependent responses in thermal nociception and other baseline measures in wildtype (WT) mice that were absent in Nape-pld KO mice. In the Complete Freund's Adjuvant (CFA) model of inflammatory arthritis, WT mice exhibited sex-dependent changes in paw edema that were lost in Nape-pld KO mice. However, there was no effect of Nape-pld deletion on arthritic pain-like behaviors (grip force deficit and tactile allodynia) in either sex, indicating that while NAPE-PLD may alter local inflammation, it does not contribute to pain-like behaviors associated with inflammatory arthritis. Collectively, these findings indicate that chronic and systemic NAPE-PLD inactivation will likely be well-tolerated, warranting further pharmacological evaluation of this target in other disease indications.

Expression of cannabinoid (CB1 and CB2) and cannabinoid-related receptors (TRPV1, GPR55, and PPARα) in the synovial membrane of the horse metacarpophalangeal joint

Background

The metacarpophalangeal joint undergoes enormous loading during locomotion and can therefore often become inflamed, potentially resulting in osteoarthritis (OA). There are studies indicating that the endocannabinoid system (ECS) modulates synovium homeostasis, and could be a promising target for OA therapy. Some cannabinoid receptors, which modulate proliferative and secretory responses in joint inflammation, have been functionally identified in human and animal synovial cells.

Objective

To characterize the cellular distribution of the cannabinoid receptors 1 (CB1R) and 2 (CB2R), and the cannabinoid-related receptors transient receptor potential vanilloid type 1 (TRPV1), G protein-related receptor 55 (GPR55) and peroxisome proliferator-activated receptor alpha (PPARα) in the synovial membrane of the metacarpophalangeal joint of the horse.

Animals

The dorsal synovial membranes of 14 equine metacarpophalangeal joints were collected post-mortem from an abattoir.

Materials and methods

The dorsal synovial membranes of 14 equine metacarpophalangeal joints were collected post-mortem from an abattoir. The expression of the CB1R, CB2R, TRPV1, GPR55, and PPARα in synovial tissues was studied using qualitative and quantitative immunofluorescence, and quantitative real-time reverse transcriptase PCR (qRT-PCR). Macrophage-like (MLS) and fibroblast-like (FLS) synoviocytes were identified by means of antibodies directed against IBA1 and vimentin, respectively.

Results

Both the mRNA and protein expression of the CB2R, TRPV1, GPR55, and PPARα were found in the synoviocytes and blood vessels of the metacarpophalangeal joints. The synoviocytes expressed the mRNA and protein of the CB1R in some of the horses investigated, but not in all.

Conclusions and clinical importance

Given the expression of the CB1R, CB2R, TRPV1, GPR55, and PPARα in the synovial elements of the metacarpophalangeal joint, these findings encouraged the development of new studies supporting the use of molecules acting on these receptors to reduce the inflammation during joint inflammation in the horse.

Trabecular Titanium for Orthopedic Applications: Balancing Antimicrobial with Osteoconductive Properties by Varying Silver Contents

Periprosthetic joint infection (PJI) and implant loosening are the most common complications after joint replacement surgery. Due to their increased surface area, additively manufactured porous metallic implants provide optimal osseointegration but they are also highly susceptible to bacterial colonization. Antibacterial surface coatings of porous metals that do not inhibit osseointegration are therefore highly desirable. The potential of silver coatings on arthroplasty implants to inhibit PJI has been demonstrated, but the optimal silver content and release kinetics have not yet been defined. A tight control over the silver deposition coatings can help overcome bacterial infections while reducing cytotoxicity to human cells. In this regard, porous titanium sputtered with silver and titanium nitride with increasing silver contents enabled controlling the antibacterial effect against common PJI pathogens while maintaining the metabolic activity of human primary cells. Electron beam melting additively manufactured titanium alloys, coated with increasing silver contents, were physico-chemically characterized and investigated for effects against common PJI pathogens. Silver contents from 7 at % to 18 at % of silver were effective in reducing bacterial growth and biofilm formation. Staphylococcus epidermidis was more susceptible to silver ions than Staphylococcus aureus. Importantly, all silver-coated titanium scaffolds supported primary human osteoblasts proliferation, differentiation, and mineralization up to 28 days. A slight reduction of cell metabolic activity was observed at earlier time points, but no detrimental effects were found at the end of the culture period. Silver release from the silver-coated scaffolds also had no measurable effects on primary osteoblast gene expression since similar expression of genes related to osteogenesis was observed regardless the presence of silver. The investigated silver-coated porous titanium scaffolds may thus enhance osseointegration while reducing the risk of biofilm formation by the most common clinically encountered pathogens.

Qing-Luo-Yin Alleviated Monocytes/Macrophages-Mediated Inflammation in Rats with Adjuvant-Induced Arthritis by Disrupting Their Interaction with (Pre)-Adipocytes Through PPAR-γ Signaling

Background

The Chinese herbal formula Qing-Luo-Yin (QLY) has been successfully used in rheumatoid arthritis treatment for decades. It exhibits notable immune and metabolism regulatory properties. Thereby, we investigated its effects on the interplay between (pre)-adipocytes and monocytes/macrophages under adjuvant-induced arthritis (AIA) circumstances.

Methods

Fat reservoir and histological characteristics of white fat tissues (WAT) in AIA rats receiving QLY treatment were examined upon sacrifice. Metabolic parameters, clinical indicators, and oxidative stress levels were determined using corresponding kits, while mRNA/protein expression was investigated by PCR and immunoblotting methods. M1 macrophage distribution in WAT was assessed by flow cytometry. The effects of QLY on (pre)-adipocytes were further validated by experiments in vitro.

Results

Compared with normal healthy controls, body weight and circulating triglyceride were declined in AIA rats, but serological levels of free fatty acids and low-density lipoprotein cholesterol were increased. mRNA IL-1β and iNOS expression in white blood cells and rheumatoid factor, C-reactive protein, anti-cyclic citrullinated peptide antibody, MCP-1 and IL-1β production in serum/WAT were up-regulated. Obvious CD86⁺CD11b⁺ macrophages were enriched in WAT. Meanwhile, expression of PPAR-γ and SIRT1 and secretion of adiponectin and leptin in these AIA rats were impaired. QLY restored all these pathological changes. Of note, it significantly stimulated PPAR-γ expression in the treated AIA rats. Accordingly, QLY-containing serum promoted SCD-1, PPAR-γ, and SIRT1 expression in pre-adipocytes cultured in vitro. AIA rats-derived peripheral blood mononuclear cells suppressed PPAR-γ and SCD-1 expression in co-cultured pre-adipocytes, but serum from AIA rats receiving QLY treatment did not exhibit this potential. The changes on PPAR-γ expression eventually resulted in varied adipocyte differentiation statuses. PPAR-γ selective inhibitor T0070907 abrogated QLY-induced MCP-1 production decline in LPS-primed pre-adipocytes and reduced adiponectin secretion.

Conclusion

QLY was potent in promoting PPAR-γ expression and consequently disrupted inflammatory feedback in WAT by altering monocytes/macrophages polarization and adipocytes differentiation.

Lipid management in rheumatoid arthritis: a position paper of the Working Group on Cardiovascular Pharmacotherapy of the European Society of Cardiology

Rheumatoid arthritis (RA) is associated with increased cardiovascular morbidity, partly due to alterations in lipoprotein quantity, quality and cell cholesterol trafficking. Although cardiovascular disease significantly contributes to mortality excess in RA, cardiovascular prevention has been largely insufficient. Because of limited evidence, optimal strategies for lipid management (LM) in RA have not been determined yet, and recommendations are largely based on expert opinions. In this position paper, we describe abnormalities in lipid metabolism and introduce a new algorithm for estimation of cardiovascular risk (CVR) and LM in RA. The algorithm stratifies patients according to RA-related factors impacting CVR (such as RA activity and severity and medication). We propose strategies for monitoring of lipid parameters and treatment of dyslipidaemia in RA (including lifestyle, statins and other lipid-modifying therapies, and disease modifying antirheumatic drugs). These opinion-based recommendations are meant to facilitate LM in RA until more evidence is available.

N-Acylethanolamine acid amidase (NAAA) inhibitor F215 as a novel therapeutic agent for osteoarthritis

Osteoarthritis (OA), characterized by cartilage damage, synovitis inflammation and chronic pain, is a common degenerative joint disease that may lead to physical disability. In the present study, we first explored the association between N-Acylethanolamine acid amidase (NAAA) and OA progression, and then examined the capability of the NAAA inhibitor F215 to attenuate osteoarthritis. Increased NAAA expressions and decreased PEA levels in synovial membrane and lumbar spinal cord were observed in MIA induced osteoarthritic rats. F215 (i.a., and i.p.) significantly protected against cartilage damage and synovial inflammation by directly increasing PEA levels in joints, or normalization of PEA levels and resolution of inflammation in spinal cord. Moreover, F215 also markedly alleviated osteoarthritic pain in rats, and the therapeutic effects of F215 were blocked by the PPAR-α antagonist MK886. The results revealed that NAAA may has been implicated in OA progression, and treatment with NAAA inhibitor F215 alleviated OA development by preventing cartilage damage, reducing inflammation, and alleviating pain. Our study suggested that NAAA inhibitor might be a novel therapeutic agent for OA treatment.

PPARs and pain

Chronic pain is a common cause of disability worldwide and remains a global health and socio-economic challenge. Current analgesics are either ineffective in a significant proportion of patients with chronic pain or associated with significant adverse side effects. The PPARs, a family of nuclear hormone transcription factors, have emerged as important modulators of pain in preclinical studies and therefore a potential therapeutic target for the treatment of pain. Modulation of nociceptive processing by PPARs is likely to involve both transcription-dependent and transcription-independent mechanisms. This review presents a comprehensive overview of preclinical studies investigating the contribution of PPAR signalling to nociceptive processing in animal models of inflammatory and neuropathic pain. We examine current evidence from anatomical, molecular and pharmacological studies demonstrating a role for PPARs in pain control. We also discuss the limited evidence available from relevant clinical studies and identify areas that warrant further research. LINKED ARTICLES: This article is part of a themed section on 8^th European Workshop on Cannabinoid Research. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.10/issuetoc.

Statins and fibrates do not affect development of spontaneous cartilage damage in STR/Ort mice

OBJECTIVE

Since statins and fibrates are capable of improving the metabolic profile of patients as well as decreasing inflammation, they are considered as potential drugs for preventing osteoarthritis (OA). The goal of the present study was to investigate the effect of these drugs in the STR/Ort spontaneous OA mouse model.

DESIGN

Male STR/Ort mice received control diet or control diet containing two different dosages of simvastatin or fenofibrate or a combination of both. Mice were euthanized after 16 weeks of treatment at the age of 24 weeks. Serum analysis for metabolic and inflammatory markers, histologic OA grading and micro computed tomography (μCT) analysis of subchondral bone plate were performed.

RESULTS

Simvastatin treatment did not have a statistically significant effect on any of the measured parameters. Fenofibrate treated mice gained less body weight (BW) and had lower serum amyloid A (SAA) levels, but higher Interleukin (IL)-1α and MIP1α than other mice. Mice treated with 200 mg/kg BW/day fenofibrate had less subchondral bone plate volume than control, but no statistically significant reduction in cartilage damage. In the combination treatment group, BW and SAA were lower than control. Overall, bodyweight, synovium membrane cell layers and SAA levels correlated to subchondral bone plate changes and subchondral bone plate changes correlated to cartilage damage.

CONCLUSIONS

Statins and fibrates did not affect development of cartilage damage in the STR/Ort spontaneous OA mouse model. Fenofibrates however, had an effect on BW, serum inflammation markers and subchondral bone plate morphology.