IntroductionThe study aimed to clarify the changes in the concentration of inflammatory mediators, proteases, and cartilage degradation biomarkers in the synovial fluid of joints in an equine osteoarthritis model.Material and MethodsOsteoarthritis was induced in eight Mongolian horses by a sterile intra-articular injection of amphotericin B, which was injected into the left carpal joint in a dose of 2 mL (25 mg/mL). The control group comprised five horses which were injected with an equal dose of sterile physiological saline into the left carpal joint. Synovial fluid was obtained at baseline and every week after injection. Test methods were based on ELISA.ResultsIn the course of the osteoarthritis, the concentration of biomarkers in joint synovial fluid showed an increasing trend. IL-1, IL-6, MMP-9, MMP-13, ADAMTS-5, CS846, GAG, HA, CTX-II, and COMP concentrations sharply increased before the onset of significant symptoms of lameness, whereas TNF-α, MMP-2, and MMP-3 concentrations rose sharply after the occurrence of such symptoms.ConclusionThe results obtained confirm that the concentrations of IL-1, IL-6, MMP-9, MMP-13, ADAMTS-5, CS846, GAG, HA, CTX-II and COMP increase substantially in equine osteoarthritis, which provides a theoretical basis for the rapid diagnosis of the disease.

In osteoarthritis (OA), activated synoviocytes and articular chondrocytes produce pro-inflammatory cytokines, such as IL-1β, that promote chondrocyte apoptosis and activate the NF-κB signaling pathway to induce catabolic factors. In this study, we examined the anti-inflammatory and anti-apoptotic effect of baicalein on IL-1β signaling and NF-κB-regulated gene products in rat chondrocytes. Rat chondrocytes were pretreated with 10 ng/ml IL-1β for 24 h and then co-treated with 10 ng/ ml IL-1β and 50 μM baicalein for 0, 12, 24, 36 and 48h. The expression levels of poly(ADP-ribose) polymerase (PARP), Bcl-2, caspase-3, matrix metalloproteinase (MMP)-9, MMP-3, cyclooxygenase (COX)-2 and SOX-9 were detected by Western blot and quantitative reverse transcription-PCR (qPCR). The effects of baicalein on the translocation and phosphorylation of the NF-κB system were studied by Western blotting and immunofluorescence. Baicalein stimulated the expression of anti-apoptotic genes and reduced the pro-apoptotic and pro-inflammatory gene products in chondrocytes. Baicalein promoted SOX-9 expression in a time-dependent manner in chondrocytes. Baicalein inhibited the NF-κB activation that was induced by IL-1β in a time-dependent manner in chondrocytes. Our results suggest that the anti-inflammatory and anti-apoptotic effects of baicalein are mediated through the inhibition of the translocation of phosphorylated p65 to the nucleus.

The purpose of the study was to define transient changes in the concentration of inflammatory biomarkers and cartilage biomarkers in the synovial fluid of joints following experimentally induced acute equine synovitis. Acute synovitis was induced in eight skeletally mature mares by a sterile intra-articular injection of 1 mL of phosphate-buffered saline (PBS) containing 0.5 ng of lipopolysaccharide (LPS). The solution was injected into the right middle carpal joint. One mL of sterile PBS was injected into the left control joint. Synovial fluid was obtained at the baseline level and at 8, 24, and 168 h after injection. The levels of inflammatory biomarkers-prostaglandin E2 (PGE2), interleukin 1β (IL-1β), and tumour necrosis factor-α (TNF-α), and cartilage turnover biomarkers-collagenase-cleavage neoepitope of type II collagen (C2C) and C-terminal crosslinked telopeptide type II collagen (CTX-II) were detected with proper assays. Single injections of LPS raised the number of synovial white blood cells and concentrations of total protein, PGE2, IL-1β, TNF-α, C2C, and CTX-II. PGE2 and IL-1β rose sharply at 8 h, while TNF-α increased steadily through 8 h and 24 h, at that point; these three factors returned to the baseline level by 168 h. The time course of C2C and CTX-II concentrations peaked sharply at 24 h, and continued to be significantly elevated over the baseline level even at 168 h. Injections of LPS into the joints led to a temporal inflammatory response, which in turn increased local release of inflammatory biomarkers and significantly altered the concentrations of cartilage markers in the synovial fluid.

The study was conducted on 24 Mongolian horses, with oligofructose-induced equine laminitis (10 g/kg b.w.). The objective of the study was to investigate the relationships among matrix metalloproteinase 2 (MMP-2), P38 mitogen-activated protein kinases (P38 MAPK), tissue inhibitor of metalloproteinase 2 (TIMP-2), lipopolysaccharides (LPS), and tumour necrosis factor-α (TNF-α) during acute developmental phase of laminitis, and to determine whether there are any characteristic tendencies. Moreover, plasma concentrations of LPS and TNF-α were measured in order to determine the time of leukocytes' activation. Eleven of the 12 horses showed clinical signs of laminitis. The contents of MMP-2 and P38 MAPK increased significantly from 8 h to 64 h, and the content of TIMP-2 decreased significantly at the same time. Plasma LPS concentrations increased significantly between 8 h and 20 h and reached a peak of 0.024 ± 0.009 EU/mL (equivalent to 3.04 ± 1.19 pg/mL) at 12 h. TNF-α concentration increased between 20 h and 36 h. This data indicates that MMP-2 plays an important role during the early acute developmental phase of oligofructose-induced equine laminitis.

Horses (n = 20) were divided into 2 groups: oligofructose (OF)-induced equine laminitis group (group OF; n = 11) which received 10 g/kg b.w. of OF dissolved in 4 L water via nasogastric intubation, and control group (NS; n = 9) which received 4 L of saline. Blood was collected at 4 h intervals over 72 h study period and analysed by ELISA, kinetic limulus amoebocyte lysate assay, and glucose-oxidase methods. The level of insulin changed significantly in horses which received OF (P < 0.01); there was a significant negative correlation between the level of adiponectin and insulin over time. The results suggested that insulin may play an important role in the development of OF-induced equine laminitis by altering the level of endothelin-1 and nitric oxide.