n-3 polyunsaturated fatty acids alleviate the progression of obesity-related osteoarthritis and protect cartilage through inhibiting the HMGB1-RAGE/TLR4 signaling pathway

Osteoarthritis (OA) is a common joint degenerative disease. There is currently no cure for OA. Dietary fatty acids have potential value in the prevention and treatment of OA. n-3 polyunsaturated fatty acids (PUFAs) have anti-inflammatory effects, but their anti-OA mechanism remains unclear. High-mobility group box 1 (HMGB1) promotes inflammation and participates the pathogenesis of OA. The purpose of this study was to investigate the protective effect of n-3 PUFAs on cartilage and whether n-3 PUFAs could exert an anti-OA effect through inhibiting HMGB1-RAGE/TLR4 signaling pathway. We established an obesity-related post-traumatic OA mice model and an in vitro study was conducted to explore the regulatory mechanism of n-3 PUFAs on HMGB1 and its signal pathway against OA. We found that diet rich in n-3 PUFAs alleviated OA-like lesions of articular cartilage with the decrease of HMGB1-RAGE/TLR4 signaling protein in mice. In SW1353 cells, DHA significantly reduced the expression of HMGB1-RAGE/TLR4 signaling protein which was up-regulated by IL-1β stimulation. HMGB1 overexpression reversed the inhibitory effect of DHA on HMGB1-RAGE/TLR4 signaling pathway. The activation of SIRT1 may participate the inhibitory effect of DHA on HMGB1-RAGE/TLR4 signaling pathway. In conclusion, n-3 PUFAs could attenuate the progression of obesity-related OA and exert protective effect on cartilage by inhibiting HMGB1-RAGE/TLR4 signaling pathway, which may be associated with the activation of SIRT1. Dietary n-3 PUFAs supplements can be considered as a potential therapeutic substance for OA.

A one-health approach to identifying and mitigating the impact of endocrine disorders on human and equine athletes

Endocrinopathies affect multiple species in ever-increasing percentages of their populations, creating an opportunity to apply one-health approaches to determining creative preventative measures and therapies in athletes. Obesity and alterations in insulin and glucose dynamics are medical concerns that play a role in whole-body health and homeostasis in both horses and humans. The role and impact of endocrine disorders on the musculoskeletal, cardiovascular, and reproductive systems are of particular interest to the athlete. Elucidation of both physiologic and pathophysiologic mechanisms involved in disease processes, starting in utero, is important for development of prevention and treatment strategies for the health and well-being of all species. This review focuses on the unrecognized effects of endocrine disorders associated with the origins of metabolic disease; inflammation at the intersection of endocrine disease and related diseases in the musculoskeletal, cardiovascular, and reproductive systems; novel interventions; and diagnostics that are informed via multiomic and one-health approaches. Readers interested in further details on specific equine performance conditions associated with endocrine disease are invited to read the companion Currents in One Health by Manfredi et al, JAVMA, February 2023.

Plasma HMGB-1 and Nucleosome Concentrations in Horses with Colic and Healthy Horses

Background

Acute gastrointestinal disease occurs commonly in horses. Novel biomarkers might improve the understanding of SIRS and aid diagnosis and determination of prognosis.

Hypotheses

Increased plasma concentrations of the biomarkers HMGB‐1 and nucleosomes are associated with severity of gastrointestinal lesions in horses; concentrations of these biomarkers will be greater in horses with lesions more likely to cause SIRS; and will provide additional information compared with standard biomarkers fibrinogen and SAA.

Animals

Thirty horses with gastrointestinal disease, 22 healthy horses.

Methods

Prospective study. Plasma samples taken on admission were used for measurement of HMGB‐1, nucleosomes, fibrinogen, and SAA. Values were compared between healthy horses and those with gastrointestinal disease, and between horses with gastrointestinal disease grouped by lesion type (inflammatory, strangulating, and nonstrangulating). Correlations between biomarkers were assessed.

Results

Plasma concentrations of all biomarkers were significantly higher in horses with gastrointestinal disease compared to healthy horses (P ≤ .001). HMGB‐1 and nucleosomes were significantly higher in inflammatory and strangulating groups compared to healthy horses (3.5‐fold and 5.4‐fold increases, respectively, for HMGB‐1 (P < .05) and 4.8‐fold and 5.6‐fold increases for nucleosomes (P < .05)), but concentrations in the group with nonstrangulating disease did not differ from healthy horses. There was significant correlation between HMGB‐1 and nucleosomes (Spearman's r = 0.623; P < .001), and fibrinogen and SAA (Spearman's r = 0.801; P < .001) but not between other biomarkers.

Conclusions and Clinical Importance

High mobility group box‐1 and nucleosomes might have use as biomarkers for horses with gastrointestinal disease. Further studies are required to determine kinetics and prognostic value of serial measurements of these biomarkers in horses.

Concentrations of stromal cell-derived factor-1 in serum, plasma, and synovial fluid of horses with osteochondral injury

OBJECTIVE

To determine whether stromal cell-derived factor-1 (SDF-1) concentrations in serum, plasma, and synovial fluid differed among untrained, race-trained, and osteochondral-injured Thoroughbred racehorses.

ANIMALS

22 racehorses without osteochondral injury and 37 racehorses with osteochondral injury.

PROCEDURES

Horses without osteochondral injury were examined before and after 5 to 6 months of race training. Horses with osteochondral injury were undergoing arthroscopic surgery for removal of osteochondral fragments from carpal or metacarpophalangeal or metatarsophalangeal joints (fetlock joints). Serum, plasma, and fetlock or carpal synovial fluid samples were obtained and analyzed for SDF-1 concentration by use of an ELISA.

RESULTS

In horses with fetlock or carpal joint injury, mean synovial fluid SDF-1 concentrations were significantly higher, serum SDF-1 concentrations were significantly lower, and synovial fluid-to-serum SDF-1 ratios were significantly higher than in untrained and trained horses. Synovial fluid SDF-1 concentrations were not significantly different between trained and untrained horses. Plasma SDF-1 concentrations were not different among the 3 groups. Results obtained with serum, compared with synovial fluid and plasma, had better sensitivity for differentiating between osteochondral-injured horses and uninjured horses. In horses with fetlock joint osteochondral injury, serum SDF-1 concentrations were correlated with radiographic and arthroscopic inflammation scores, but not arthroscopic cartilage scores.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that serum SDF-1 concentrations were more sensitive than plasma and synovial fluid concentrations for detection of osteochondral injury in the fetlock or carpal joint of racehorses. Analysis of serum and synovial SDF-1 concentrations in horses with experimentally induced joint injury may help define the onset and progression of post-traumatic osteoarthritis and aid in the evaluation of anti-inflammatory treatments.

Effects of high mobility group box protein-1, interleukin-1β, and interleukin-6 on cartilage matrix metabolism in three-dimensional equine chondrocyte cultures

The effects of high mobility group box protein (HMGB)-1, interleukin (IL)-1β, and IL-6 on equine articular chondrocytes were investigated, with emphasis on detecting differences between anatomical sites exposed to different loading in vivo, using three-dimensional (3D) cell cultures established with chondrocytes from dorsal radial facet (DRF, highly loaded) and palmar condyle (PC, less loaded) of the third carpal bone (C3). Expression of important genes involved in cartilage metabolism, presence of glycosaminoglycans and cartilage oligomeric matrix protein (COMP) in pellets, and concentrations of matrix metalloproteinase (MMP)-13 and aggrecan epitope CS 846 were evaluated. Compared to controls, IL-1β treatment increased gene expression of versican, matrix-degrading enzymes, and tissue inhibitor of metalloproteinase (TIMP)-1, and decreased aggrecan and collagen type I and type II expression. In addition, IL-1β-treated pellets showed decreased safranin O staining and increased COMP immunostaining and MMP-13 concentrations in culture supernatants. Effects of IL-6 and HMGB-1 on gene expression were variable, although upregulation of Sry-related high-mobility group box 9 (Sox9) was often present and statistically increased in HMGB-1-treated pellets. Response to cytokines rarely differed between DRF and PC pellets. Thus, site-associated cartilage deterioration in equine carpal osteoarthritis (OA) is not explained by topographically different responses to inflammatory mediators. Differences in gene expressions of structural matrix proteins in untreated DRF and PC pellets were noted in the youngest horses, which may indicate differences in the chondrocytes potential to produce matrix in vivo. Overall, a strong catabolic response was induced by IL-1β, whereas slight anabolic effects were induced by IL-6 and HMGB-1.