Age-related effects on markers of inflammation and cartilage metabolism in response to an intra-articular lipopolysaccharide challenge in horses.

Eighteen Quarter Horses were used in a randomized complete design for a 28-d experiment to evaluate age-related effects on inflammation and cartilage turnover after induction of a single inflammatory insult using lipopolysaccharide (LPS). Horses were grouped by age as yearlings (3 males and 3 females), 2 to 3 yr olds (2/3 yr old; 2 males and 4 females), and skeletally mature 5 to 8 yr olds (mature; 2 males and 4 females). On d 0, all horses were individually housed and fed diets that met or exceeded requirements. On d 14, horses were challenged with an intra-articular injection of LPS. Radial carpal joints were randomly assigned to receive 0.5 ng LPS solution obtained from O55:B5 or 0.8 mL sterile lactated Ringer's solution as a contralateral control. Synovial fluid was collected prior to LPS injection at h 0 before injection and at 6, 12, 24, 168, and 336 h after injection. Samples were analyzed using commercial ELISA kits for PGE, collagenase cleavage neoepitope (C2C), and carboxypropeptide of type II collagen (CPII). Heart rate (HR), respiratory rate (RR), and rectal temperature (RT) were monitored over the initial 24 h and carpal circumference and surface temperature were also recorded, with additional measurements at 168 and 336 h. Data were analyzed using PROC MIXED of SAS. Values for RT, HR, and RR were within the normal range for each age group. Heart rate and RT were influenced by age ( < 0.01), whereas RR was unaffected ( ≤ 0.21). Joint circumference was not influenced by age of horse ( = 0.84), but circumference and surface temperature increased ( < 0.01) over time across all age groups. Synovial PGE concentrations tended ( = 0.09) to be influenced by age, with yearlings having lower ( = 0.03) concentrations than mature horses. Concentrations of synovial C2C were affected by age of horse, with yearlings and 2/3 yr olds having lower ( < 0.01) concentrations than mature horses. Similarly, synovial CPII was influenced by age, with yearlings and 2/3 yr olds having lower ( ≤ 0.02) concentrations than mature horses. Ratios of anabolic CPII to catabolic C2C varied by age, with mature and 2/3-yr-old horses having greater ( < 0.01) values compared with yearlings. These results indicate that inflammation and the corresponding cartilage turnover in response to LPS administration vary with age.

Influence of oral glucosamine supplementation in young horses challenged with intra-articular lipopolysaccharide.

Fourteen yearling Quarter horses (351 to 470 kg) were utilized in a randomized complete block design to evaluate potential of glucosamine hydrochloride (HCl) to mitigate intra-articular inflammation following a single inflammatory insult. Horses were blocked by BW, age, and sex, and randomly assigned to treatments for a 98-d experiment. Treatments consisted of a control diet (CON; = 7) fed 1% BW per d (as-fed) of concentrate only or a treatment diet ( = 7) of concentrate top dressed with 30 mg/kg BW glucosamine HCl (99.6% purity; GLU30) offered at 12 h intervals. Horses were maintained in individual stalls and offered approximately 1% BW per d of coastal bermudagrass hay (). Plasma and synovial fluid samples were obtained every 14 and 28 d, respectively, and stored at -20°C, before analysis of glucosamine via HPLC. On d 84, an intra-articular lipopolysaccharide (LPS) challenge was conducted on all horses to determine ability of dietary glucosamine HCl supplementation to mitigate joint inflammation and cartilage metabolism. Carpal joints were randomly selected to receive 1 of 2 intra-articular treatments and included sterile lactated Ringer's (control; Contra) only or 0.5 ng LPS solution (LPS) obtained from O55:B5 into the radial carpal joint. Synovial fluid was obtained at pre-injection h 0 and 6, 12, 24, 128, and 336 h post-injection, and was analyzed for prostaglandin E (PGE), carboxypeptide of type II collagen (CPII) and collagenase cleavage neopeptide (C2C) biomarkers by commercial ELISA kits. Data were analyzed using PROC MIXED procedure of SAS. Plasma and synovial glucosamine tended ( = 0.10 and = 0.06, respectively) to increase over time in response to GLU30 compared to CON. There was a treatment by time interaction ( ≤ 0.01), with GLU30 increasing plasma glucosamine concentrations at 28 and 42 d when compared to CON. A treatment by time interaction ( ≤ 0.01) was observed with GLU30 increasing synovial glucosamine levels at d 28 and 84 ( ≤ 0.01 and = 0.05, respectively). Intra-articular LPS increased ( ≤ 0.01) synovial PGE, C2C, and CPII levels. GLU30 decreased synovial PGE and C2C concentrations when compared to CON ( = 0.04 and = 0.05, respectively), while synovial levels of CPII increased ( ≤ 0.01) in GLU30 horses. These results indicate the potential for oral glucosamine HCl to mitigate intra-articular inflammation and influence cartilage turnover in a young horse model.