Evaluation of conjugated linoleic acid supplementation on markers of joint inflammation and metabolism in young horses challenged with lipopolysaccharide
Seventeen yearling Quarter horses were used in a randomized complete block design to evaluate potential of dietary CLA to mitigate intra-articular inflammation and cartilage metabolism following a single inflammatory insult. Horses were blocked by age, BW and sex and randomly assigned to treatment for a 56-day trial. Treatments consisted of a commercial concentrate offered at 1% BW (as fed) supplemented with either 1% soybean oil (CON; n=6), 0.5% soybean oil and 0.5% CLA (LOW; n=5; Lutalin®, BASF Corp.), or 1% CLA (HIGH; n=6; 55% purity) top-dressed daily. Horses were fed individually at 12 h intervals and offered 1% BW daily (as-fed) coastal bermudagrass (Cynodon dactylon) hay. On day 42, an LPS challenge was conducted. Carpal joints were randomly assigned to receive intra-articular injections of 0.5 ng LPS derived from Escherichia coli 055:B5 or sterile lactated Ringer’s solution as a contralateral control. Synovial fluid samples were taken via arthrocentesis at pre-injection h 0 and 6, 12, 24, 168 and 336 h post-injection, and were analyzed for prostaglandin E2 (PGE2), carboxypeptide of type II collagen (CPII), and collagenase cleavage neopeptide (C2C) using commercial ELISA kits. Vitals, including heart rate, rectal temperature and respiration rate were monitored at 0, 6, 12 and 24 h; and carpal circumference and surface temperatures were also recorded. Data were analyzed using PROC MIXED procedure of SAS. Vitals were not significantly different across treatments (P ≥ 0.13) and remained within normal ranges throughout the LPS challenge. Synovial PGE2 concentrations were not influenced by dietary treatment (P = 0.15). Synovial C2C concentrations were influenced by treatment (P = 0.05) with LOW and HIGH horses having lesser C2C than CON. Across all treatments C2C concentrations varied over time (P < 0.01) with values decreasing from 0 h to 6 h, peaking at 12 h and decreasing to 336 h. Levels of synovial CPII tended to be influenced by treatment (P =0.10) with LOW and HIGH horses having greater concentrations compared to CON. Regardless of diet, CPII concentrations increased over time (P < 0.01) with levels peaking at 24 h and decreasing to 336 h. In conclusion, CLA supplementation did not influence PGE2 concentrations following the LPS challenge; however, horses receiving CLA had lesser C2C and greater CPII concentrations, indicating less degradation and greater synthesis of cartilage in response to acute inflammation.
CLA, Synovial, LPS, Cartilage