Comparative analysis of cytokine gene expression in cerebrospinal fluid of horses without neurologic signs or with selected neurologic disorders.

The study investigates the gene expression for cytokines, proteins involved in immune responses, in the cerebrospinal fluid (CSF) of horses experiencing different neurological conditions and healthy horses. The findings suggest that different neurological diseases correspond to unique cytokine gene expression profiles in the CSF.

Methodology

• The study involved 41 horses grouped into five categories – 12 healthy horses, 8 with cervical stenotic myelopathy (CSM), 9 with West Nile virus (WNV) encephalitis, 6 with equine protozoal myeloencephalitis (EPM), and 6 with spinal cord injuries.
• Total RNA was extracted from nucleated cells in each horse’s CSF and converted into cDNA. The gene expression was subsequently measured by implementing a real-time PCR assay.
• Final quantitation of the gene expression was achieved through the comparative threshold cycle method.

Results

• The study revealed that in healthy horses, cytokine genes expressed by the nucleated cells in the CSF covered a balance between proinflammatory tumor necrosis factor-alpha (TNF-alpha), anti-inflammatory cytokines like interleukin (IL)-10 and transforming growth factor (TGF)-beta, and Th1 mediators such as interferon (IFN)-gamma.
• In horses with CSM, the cells mainly exhibited gene expression for TNF-alpha, TGF-beta, and IL-10.
• In horses suffering from WNV encephalitis, nucleated cells in the CSF primarily expressed genes for IL-6 and TGF-beta.
• Equine cells affected by EPM demonstrated significant gene expression for IL-6, IL-8, IL-10, TNF-alpha, IFN-gamma, and TGF-beta.
• In horses with spinal cord injuries, the major gene expressions recorded were for IL-6, IFN-gamma, TGF-beta and to a lesser extent for IL-2, IL-10, and TNF-alpha.
• Expression of the Interleukin-8 gene was only noted in horses suffering from infectious diseases.

Conclusions

• The results, although drawn from small sample groups, strongly suggest distinctive gene signatures expressed by nucleated cells in the CSF, depending on the presence and type of neurological disorders.
• A better understanding of these gene expression patterns could potentially aid in enhancing the diagnostic accuracy and treatment strategies for equine neurological disorders in the future.