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

Objective - To determine gene transcription for cytokines in nucleated cells in CSF of horses without neurologic signs or with cervical stenotic myelopathy (CSM), West Nile virus (WNV) encephalitis, equine protozoal myeloencephalitis (EPM), or spinal cord trauma. Animals - 41 horses (no neurologic signs [n = 12], CSM [8], WNV encephalitis [9], EPM [6], and spinal cord trauma [6]). Procedures - Total RNA was extracted from nucleated cells and converted into cDNA. Gene expression was measured by use of real-time PCR assay and final quantitation via the comparative threshold cycle method. Results - Cytokine genes expressed by nucleated cells of horses without neurologic signs comprised a balance between proinflammatory tumor necrosis factor-α (TNF-α), anti-inflammatory cytokines (interleukin [IL]-10 and transforming growth factor [TGF]-β), and Th1 mediators (interferon [IFN]-γ). Cells of horses with CSM mainly expressed genes for TNF-α, TGF-β, and IL-10. Cells of horses with WNV encephalitis mainly expressed genes for IL-6 and TGF-β. Cells of horses with EPM mainly had expression of genes for IL-6, IL-8, IL-10, TNF-α, IFN-γ, and TGF-β. Cells from horses with spinal cord trauma had expression mainly for IL-6; IFN-γ; TGF-β; and less frequently, IL-2, IL-10, and TNF-α. Interleukin-8 gene expression was only detected in CSF of horses with infectious diseases. Conclusions and clinical relevance - Despite the small number of CSF samples for each group, results suggest distinct gene signatures expressed by nucleated cells in the CSF of horses without neurologic signs versus horses with inflammatory or traumatic neurologic disorders.