Resumo

After spinal cord injury (SCI) there is, at the lesion site, a degenerative process which causes neuronal death, glial activation and a prominent peripheral immunological response. Neutrophils are the first cells recruited to the injury site, followed by macrophages and lymphocytes. Understanding the immunological response may guide researchers to develop suitable therapeutic strategies. Some authors have reported that SCI in genetically modified mice, such as BALB/C and 129X1/SvJ, show attenuated inflammatory response and deficit in macrophage recruitment, respectively, and this is correlated with the functional recovery, but this issue is still controversial. Galectin-3 (Gal-3) is a pleiotropic molecule involved in many cellular functions like cell proliferation and differentiation, extracellular matrix adhesion, apoptosis and, inflammatory cells activation and recruitment to the lesion area. Previous reports show the influence of Gal-3 in the myeloid and lymphoid cells proliferation and activation, and that the lack of this protein may attenuate the inflammatory response. Thus, we investigated the inflammatory response in C57Bl/6 Gal-3 knockout (KO) and wildtype (WT) mice after SCI, in order to evaluate its effect on regeneration of the central nervous system. For this purpose, 1 week after injury, we analyzed the lesion size by H-E staining, followed by immunoreaction for glial fibrillary acidic protein (GFAP) and F4/80 (to evaluate macrophages infiltration). Spinal cord semithin cross sections were obtained for histomorphometric analysis, 4 weeks after lesion. The functional recovery was evaluated weekly up to 4 weeks post injury, by BMS. In order to clarify the acute cell response we also analyzed the granulocytes and monocytes population in peripheral blood and bone marrow, by flow citometry, 96h after lesion. We observed that Gal-3 KO mice presented smaller lesion size than WT mice. No differences were found between the groups in the GFAP immunostaining analysis, but F4/80 immunoreactivity was decreased in KO mice as compared to WT. No morphological differences were observed between semithin transverse sections 4 weeks after lesion. However, the number of preserved or regenerating fibers was higher in KO compared to WT mice. Gal-3 KO animals showed improved functional recovery compared to WT, by BMS. KO animals presented less monocytes and granulocytes than WT in peripheral blood and bone marrow by flow citometry analysis. Thus, our results suggest an attenuated acute inflammatory response after compressive SCI in Gal-3 KO mice and this may correlate with the better morphological and functional outcome observed in these animals. Supported by: CAPES, CnPQ, FAPERJ