mRNA expression of genes involved in inflammation and haemostasis in equine fibroblast-like synoviocytes following exposure to lipopolysaccharide, fibrinogen and thrombin

In vitro effects of monophosphoryl lipid A and Poly I:C combination on equine cells

BACKGROUND

Toll-like receptor (TLR) agonists have been used as adjuvants to modulate immune responses in both animals and humans.

OBJECTIVES

The objective of this study was to evaluate the combined effects of the TLR 4 agonist monophosphoryl lipid A (MPL) and the TLR 3 agonist polyinosinic:polycytidylic acid (Poly I:C) on equine peripheral blood mononuclear cells (PBMCs), monocyte-derived dendritic cells (MoDCs), and bone marrow-derived mesenchymal stromal cells (BM-MSCs).

METHODS

The PBMCs, MoDCs, and BM-MSCs collected from three mixed breed horses were treated with MPL, Poly I:C, and their combination. The mRNA expression of interferon gamma (IFN-γ), interleukin (IL)-1β, IL-4, IL-6, IL-8, IL-12p40, tumor necrosis factor alpha (TNF-α), vascular endothelial growth factor (VEGF), and monocyte chemoattractant protein-1 (MCP-1) was determined using real-time polymerase chain reaction.

RESULTS

The combination of MPL and Poly I:C significantly upregulated immunomodulatory responses in equine cells/ without cytotoxicity. The combination induced greater mRNA expression of pro-inflammatory cytokines IFN-γ and IL-6 than MPL or Poly I:C stimulation alone in PBMCs. In addition, the combination induced significantly higher mRNA expression of IL-1β, IL-6, and IL-12p40 in MoDCs, and IL-8, MCP-1, and VEGF in BM-MSCs compared to stimulation with a single TLR agonist.

CONCLUSIONS

The combination of MPL and Poly I:C can be used as a potential adjuvant candidate for vaccines to aid in preventing infectious diseases in horses.

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.

Monocyte chemoattractant protein‑1 promotes the proliferation, migration and differentiation potential of fibroblast‑like synoviocytes via the PI3K/P38 cellular signaling pathway

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation of the joints and joint destruction. Monocyte chemoattractant protein 1 (MCP‑1) is highly expressed in the joints of patients suffering from RA. The present study aimed to evaluate the effects of MCP‑1 on the phenotype of fibroblast‑like synoviocytes (FLSs) and their differentiation potential towards vascular endothelial cells. The expression of MCP‑1 in collagen‑induced arthritis (CIA) rats was investigated by PCR, ELISA and immunohistology. Cell proliferation induced by MCP‑1 was measured using a Cell Counting Kit‑8 (CCK‑8) and 5‑Bromo‑2‑deoxyuridine ELISA assay. In addition, the effects of MCP‑1 on the migration of FLSs was examined using a Transwell assay. Activation of PI3K and P38 were investigated by western blotting following MCP‑1 treatment. The vascular endothelial cell markers, tumor necrosis factor alpha (TNF‑α) and interleukin‑1 beta (IL‑β), were also examined by western blotting. LY294002 [PI3K inhibitor, (LY)] and SB203580 [P38 inhibitor, (SB)] were used to examine the proliferative and pro‑differentiation effect of PI3K and P38. The present findings showed that the expression level of MCP‑1 in the synovium of CIA rats was significantly higher compared with controls. The present in vitro study suggested that MCP‑1 increased the FLSs cell numbers with a maximal effect at 200 ng/ml, and induced the maximal phosphorylation of PI3K at 15 min and P38 at 30 min. In addition, MCP‑1 stimulation significantly increased the migration of FLSs. Furthermore, MCP‑1‑induced the expression of vascular endothelial growth factor and CD31 in FLSs. Suppression of PI3K and P38 was found to reduce MCP‑1 induced FLSs proliferation and migration, and decreased the expression levels of angiogenesis markers increased following MCP‑1 treatment. MCP‑1 was also found to increase the expression levels of both TNF‑α and IL‑β. Therefore, MCP‑1 could promote the proliferation and migration of FLSs, and was found to increase the expression levels of various angiogenesis markers via PI3K/P38, suggesting a role for this pathway in synovium hyperplasia in RA.

The P2X7 receptor (P2X7R)-specific antagonist A804598 inhibits inflammatory reaction in human fibroblast-like synoviocytes

Activation of the P2X7 receptor (P2X7R) has been found to increase expression of tumor necrosis factor-α (TNF-α) in the joints and synovial lining of patients with rheumatoid arthritis (RA). Increased expression of TNF-α promotes joint destruction through deterioration of type II collagen by matrix metalloproteinases (MMPs), expression of proinflammatory cytokines, oxidative stress, and activation of cellular signaling pathways. In the present study, we exposed fibroblast-like synoviocytes (FLSs) to TNF-α in the presence and absence of the P2X7R antagonist A804598. We then employed real time PCR and western blot analysis to analyze the mRNA and protein expression levels of P2X7R in both control and RA-FLSs. We confirmed that P2X7R is expressed on FLSs and is upregulated in RA-FLSs and FLSs exposed to TNF-α. Importantly, we also demonstrate the ability of P2X7R antagonism using A804598 to suppress oxidative stress, expression of interleukin (IL)-1β, IL-6, MMP-1, MMP-3, MMP-13 as well as activation of the Janus family of tyrosine kinase/signal transducer and activator of transcription (JAK1/STAT3) proinflammatory signaling pathway. These findings implicate a novel role of antagonism of P2X7R as a target for the treatment and prevention of RA.

Morphine, but not methadone, inhibits microsomal prostaglandin E synthase-1 and prostaglandin-endoperoxide synthase 2 in lipopolysaccharide-stimulated horse synoviocytes

Osteoarthritis (OA) is one of the main locomotor disorders in horses. Although nonsteroidal anti-inflammatory drugs are the first-line treatment for OA, opioids could also be used. In previous studies, opioids showed promising anti-inflammatory and analgesic effects. In this study, we aimed to investigate the effects of two opioids (morphine and methadone) against inflammation in lipopolysaccharide (LPS)-stimulated synoviocytes by analyzing microsomal prostaglandin E synthase-1 (mPGES-1) and prostaglandin-endoperoxide synthase 2 (PTGS2) expression. Synoviocytes were obtained from the joints at the distal limbs of dead animals. The cytotoxic effects of LPS, morphine, and methadone were investigated by using a cell viability assay with crystal violet dye. Synoviocytes were treated with LPS, LPS plus morphine, or LPS plus methadone for 3, 6, and 12 h, and mPGES-1 and PTGS2 expression was measured using real-time polymerase chain reaction. LPS, and morphine did not affect the viability of synoviocytes, even at high concentrations. LPS treatment increased mPGES-1 and PTGS2 expression, whereas morphine inhibited the increase in mPGES-1 and PTGS2 expression in LPS-stimulated synoviocytes. Methadone did not inhibit mPGES-1 or PTGS2 expression. These results suggest that morphine may exhibit anti-inflammatory effect; therefore, it might be beneficial for the treatment of OA.

In vitro study of matrix metalloproteinases 1, 2, 9, 13 and serum amyloid A mRNAs expression in equine fibroblast-like synoviocytes treated with doxycycline

Application of synthetic matrix metalloproteinases (MMPs) inhibitors, such as doxycycline is one of the possible therapeutic options for osteoarthritis. However, little is known about the protective mechanism of doxycycline in equine models on MMPs inhibitors as well as on serum amyloid A (SAA) gene expression. This study investigated the effects of doxycycline on mRNA expression of MMP-1, MMP-2, MMP-9, MMP-13, and SAA of equine fibroblast-like synoviocytes (FLSs). The FLSs were established from synovial fluids of clinically normal metacarpophalangeal joints of 6 skeletally mature horses. The cells were treated with either 10 or 100 μg/mL of doxycycline for 48 h. The mRNA expression of MMP-1, MMP-2, MMP-9, MMP-13, and SAA were assessed using real-time polymerase chain reaction (PCR). Treatment with doxycycline resulted in significantly decreased mRNA expression of MMP-1 in FLSs at both concentrations (P = 0.001). No significant differences were detected among groups for MMP-2, MMP-9, and MMP-13 (P > 0.05). Only a tendency towards a decrease in mRNA expression level of SAA in the presence of doxycycline could be detected. Doxycycline inhibits MMP-1 gene expression at the transcript level. These findings indicate that doxycycline can protect the articular environment through inhibition of MMP-1 at transcript level.

Regulatory effect of anti-gp130 functional mAb on IL-6 mediated RANKL and Wnt5a expression through JAK-STAT3 signaling pathway in FLS

We investigated the effect on rheumatoid arthritis (RA) of an anti-gp130 monoclonal antibody (mAb) and its mechanism using RA fibroblast-like synoviocytes (FLS) and a collagen antibody–induced arthritis (CAIA) mouse model. We determined the interleukin 6 (IL-6), IL-6 receptor α (IL-6Rα), gp130, receptor activator of nuclear factor κB ligand (RANKL), matrix metalloproteinase 3 (MMP3), TIMP metallopeptidase inhibitor 1 (TIMP1), and Bcl-2 levels in RA and osteoarthritis (OA) serum and synovial fluid. RA FLS were cultured with or without IL-6/IL-6Rα; WNT5A and RANKL levels were detected. We generated an anti-gp130 mAb (M10) with higher affinity and specificity, blocked IL-6 signaling with it, and assessed its effects on the CAIA model, WNT5A and RANKL expression, and signal transducer and activator of transcription 3 (STAT3) phosphorylation. The IL-6 signaling system in patients with RA was increased; RANKL, MMP3, TIMP1, and Bcl-2 in RA bone were elevated. IL-6/IL-6Rα increased RA FLS WNT5A and RANKL expression. M10 ameliorated arthritis in the CAIA model, and inhibited RANKL, WNT5A, and Bcl-2 expression in RA FLS by blocking IL-6 signaling, likely via Janus kinase–STAT3 pathway downregulation. The IL-6–soluble IL-6Rα–gp130 complex is hyperactive in RA and OA. M10 may be the basis for a novel RA treatment drug.

Changes in concentrations of haemostatic and inflammatory biomarkers in synovial fluid after intra-articular injection of lipopolysaccharide in horses

Background

Septic arthritis is a common and potentially devastating disease characterized by severe intra-articular (IA) inflammation and fibrin deposition. Research into equine joint pathologies has focused on inflammation, but recent research in humans suggests that both haemostatic and inflammatory pathways are activated in the joint compartment in arthritic conditions. The aim of this study was to characterize the IA haemostatic and inflammatory responses in horses with experimental lipopolysaccharide (LPS)-induced joint inflammation. Inflammation was induced by IA injection of LPS into one antebrachiocarpal joint of six horses. Horses were evaluated clinically with subjective grading of lameness, and blood and synovial fluid (SF) samples were collected at post injection hours (PIH) -120, −96, −24, 0, 2, 4, 8, 16, 24, 36, 48, 72 and 144. Total protein (TP), white blood cell counts (WBC), serum amyloid A (SAA), haptoglobin, iron, fibrinogen, thrombin-antithrombin (TAT) and d-dimer concentrations were assessed in blood and SF.

Results

Intra-articular injection of LPS caused local and systemic signs of inflammation including increased rectal temperature, lameness and increased joint circumference and skin temperature. Most of the biomarkers (TP, WBC, haptoglobin, fibrinogen and TAT) measured in SF increased quickly after LPS injection (at PIH 2–4), whereas SAA and d-dimer levels increased more slowly (at PIH 16 and 144, respectively). SF iron concentrations did not change statistically significantly. Blood WBC, SAA, haptoglobin and fibrinogen increased and iron decreased significantly in response to the IA LPS injection, while TAT and d-dimer concentrations did not change. Repeated pre-injection arthrocenteses caused significant changes in SF concentrations of TP, WBC and haptoglobin.

Conclusion

Similar to inflammatory joint disease in humans, joint inflammation in horses was accompanied by an IA haemostatic response with changes in fibrinogen, TAT and d-dimer concentrations. Inflammatory and haemostatic responses were induced simultaneously and may likely interact. Further studies of interactions between the two responses are needed for a better understanding of pathogenesis of joint disease in horses. Knowledge of effects of repeated arthrocenteses on levels of SF biomarkers may be of value when markers are used for diagnostic purposes.

Platelet-rich plasma inhibits inflammatory factors and represses rheumatoid fibroblast-like synoviocytes in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic disease affecting daily life of numerous patients, and uncontrolled proliferation of synovial fibroblasts plays vital role during the pathology of RA. Platelet-rich plasma (PRP), widely used in tissue regeneration and pain management, is rarely studied in RA. This study aims to investigate the effect of PRP on synovial fibroblasts during RA. Rheumatoid fibroblast-like synoviocyte MH7A cells were stimulated by lipopolysaccharide (LPS) to simulate RA conditions and treated with PRP, after that the concentration of inflammatory factors interleukin (IL) 1β, tumor necrosis factor alpha (TNFα) and IL6 in the supernatant of culture medium was quantified by ELISA. MTT assay, flow cytometry and tube formation assay were performed to assess changes in cell viability, apoptosis and effect on angiogenesis in vitro, respectively. Besides, the expression levels of main factors in the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signal pathway were examined. Results showed that PRP markedly inhibited the production of IL1β, TNFα and IL6 (P < 0.05) that was stimulated by LPS. LPS promoted MH7A cell viability, inhibited apoptosis and accelerated angiogenesis in vitro, while PRP could markedly relieve these effects (P < 0.05). The mRNA and protein levels of AKT1, PI3K (p58) and nuclear factor κ beta were elevated by LPS and then suppressed by PRP (P < 0.01). This study uncovered the potential of PRP in inhibiting inflammation, repressing synovial fibroblasts and regulating the PI3K/AKT signaling, providing basic proof for future application of PRP in managing RA. Further investigation is necessary to reveal detailed mechanism of PRP.