Instituto de Biomedicina de Sevilla (IBiS), Lab 210

Author Of 1 Presentation

Experimental Models Poster Presentation

P0977 - Melatonin reduces disability in experimental autoimmune encephalomyelitis by impairing immune cells migration and entry into the CNS (ID 1625)

Abstract

Background

Multiple sclerosis (MS) is a neurodegenerative disease that mainly affects young adults. It is characterized by infiltrated immune cells to the central nervous system (CNS) and the blood-brain barrier (BBB) disruption. Circulating immune cells are attracted to the CNS blood vessels by chemokines, such as CCL2, CCL19, CCL20, CXCL12, and CX3CL1, whose receptors are expressed by T cells and others. Consequently, immune cells cross the BBB by interacting with ICAM-1- and VCAM-1-expressing endothelial cells through the LFA-1 adhesion molecule. Immunomodulatory and antioxidant effects of melatonin (MLT) have been demonstrated on experimental autoimmune encephalomyelitis (EAE).

Objectives

The objective of this study was to evaluate the effects of melatonin on chemoattractant and adhesion molecules responsible for immune cell infiltration into the CNS and the integrity of BBB in EAE.

Methods

EAE was induced in 8-weeks female C57BL/6N mice according to the previous protocol described by our group and daily MLT (80 mg/kg) was intraperitoneally daily administered from day 0. Clinical signs of EAE were assessed with the following scoring system: 0, no signs; 1, flaccid tail; 2, impaired righting reflex and/or gait; 3, partial hind limb paralysis; 4, total hind limb paralysis; and 5, hind limb paralysis with partial front limb paralysis. Brains and spinal cords were collected on days 5 (during the induction), 10 (disease onset), and 15 (peak of disease) post-induction (p.i.). The relative expression of chemokines and adhesion molecules was quantified by RT-qPCR, and assessment of BBB integrity was carried out by the immunohistochemical detection of albumin in the capillaries of spinal cords.

Results

We showed that MLT ameliorated EAE, down-regulating the mRNA expression of all chemokine receptors studied and the ICAM-1, VCAM-1 and LFA-1 adhesion molecules in the spinal cord during the clinical onset, and in the spinal cord and brain during the peak of the disease. Also, in this last period, MLT down-regulated the mRNA expression of CCL2 and CCL19 (brain and spinal cord) and CCL20 (brain). MLT also protected BBB integrity, since treated animals showed strong immunostaining signal of albumin inside spinal cord’s blood vessels, while controls showed weak (day 10 p.i) or almost none (day 15 p.i.) albumin signal inside blood vessels. Accordingly, melatonin decreased the frequency of CD45high infiltrating immune cells isolated from the CNS.

Conclusions

In conclusion, MLT impairs the expression of chemokines and adhesion molecules in the CNS and protects the BBB, thus reducing migration and infiltration of immune cells into the CNS.

Collapse