Oral rosmarinic acid-enhanced Mentha spicata modulates synovial fluid biomarkers of inflammation in horses challenged with intra-articular LPS.

The research demonstrates that a specific type of mint, high in rosmarinic acid, has beneficial effects in reducing biomarkers of inflammation in horses challenged with inflammatory substances.

Introduction to the Research

• The research focuses on the impact of high-rosmarinic acid mint (HRAM) when added to equine feed. The objective is to determine its effects on horses subjected to intra-articular injections of lipopolysaccharide (LPS), a substance known to induce an inflammatory response.
• The research relies on a previous study that showed HRAM could effectively inhibit the release of prostaglandin E(2) (PGE(2)), nitric oxide (NO) and glycosaminoglycan (GAG), substances linked to inflammation, when exposed to LPS in vitro (i.e., in a controlled laboratory environment).
• The current study tests these findings in vivo, with eight horses divided into two groups. One group was given HRAM in their feed while the other group was not.

Method of the Research

• The horses were first put on their respective feeds for 21 days. Following this, they were injected with LPS into their intercarpal joint, which would induce an inflammatory response.
• Synovial fluid samples were taken at identified intervals before and after the LPS injection and analysed for levels of PGE(2), GAG and NO. Other markers of inflammation, protein, and total nucleated cells counts were also examined.
• Blood biochemistry and haematology screens were conducted at similar intervals to evaluate the overall health of the horses and to track any changes that could be attributed to the HRAM intake.

Findings of the Research

• The findings suggest that horses fed with HRAM demonstrated a significant reduction in LPS-induced PGE(2) and GAG in their synovial fluid.
• In the blood work, total white blood cell count, segmented neutrophils, and lymphocytes were reduced compared to the baseline and control. However, the nucleated cell count in the synovial fluid was increased compared to both baseline and control groups.
• There was also a tendency to increase complement recognition protein accumulation in the synovial fluid of the horses on HRAM, suggesting potential modulation of immune response.

Conclusion of the Research

• The study concludes that adding HRAM to equine feed appears to alter biomarkers of inflammation in the synovial fluid of LPS-challenged horses.
• The straightforward suggestion from this research is that HRAM could be utilised as a dietary additive to manage joint inflammation in horses. However, further research, preferably on a larger scale, is recommended to validate these findings and further explore the effects of HRAM on synovial fluid cell counts and its possible role in complement signalling.