PEPITEM Reduces Annexin V Immunoreactivity in Spinal Cord Tissue from Experimental Autoimmune Encephalomyelitis Mice

INTRODUCTION: Multiple sclerosis is a chronic autoimmune demyelinating disease of the central nervous system, and experimental autoimmune encephalomyelitis is widely used as a murine model to study its immunopathological features. PEPITEM regulates leukocyte trafficking; however, its effect on apoptosis-associated tissue changes in EAE remains unclear. This study aimed to determine whether prophylactic or therapeutic administration of PEPITEM alters Annexin V immunoreactivity in spinal cord sections from EAE mice. METHODS: EAE was induced in female C57BL/6 mice using MOG35-55 immunization. Mice received scrambled peptide or PEPITEM using therapeutic or prophylactic regimens. Paraffinembedded lumbar spinal cord sections were analyzed by Annexin V immunofluorescence staining with DAPI nuclear counterstaining. RESULTS: Both therapeutic and prophylactic PEPITEM-treated EAE groups showed reduced Annexin V immunoreactivity compared with their corresponding scrambled peptide-treated EAE controls. DAPI staining suggested better preservation of nuclear distribution and morphology in PEPITEM-treated groups. DISCUSSION: These findings complement previous PEPITEM-EAE studies reporting reduced CNS inflammation, leukocyte infiltration, demyelination, and immune-trafficking gene expression. Annexin V immunofluorescence is supportive rather than definitive, and further validation is needed. CONCLUSION: PEPITEM treatment was associated with reduced Annexin V immunoreactivity in EAE spinal cord sections, suggesting reduced apoptosis-associated tissue injury.