Effect of macrophages on astrocytes under 810nm low level laser therapy

English Keywords:Spinal cord injury  Low level laser therapy  M1 macrophage  Astrocyte  Chondroitin sulfate proteoglycans

English Abstract:

  【Abstract】 Objectives: To investigate the effects of macrophages controlled by 810nm low level laser on the activation of astrocytes and the secretion of chondroitin sulfate proteoglycans(CSPG). Methods: An animal model of spinal cord injury was established, including spinal cord injury group(SCI) and low level laser therapy group(LLLT). Immunofluorescence was used to detect the expression of glial fibrillary acidic protein (GFAP) and CSPG in spinal cord injury area. The macrophage-astrocyte model was established in vitro, which was divided into Ctrl group(blank control), M1 group(astrocytes were cultured in M1 conditioned medium) and M1+LLLT group(astrocytes were cultured in M1 conditioned medium with low level laser), Western Blot was used to detect the expression of M1 marker inducible nitric oxide synthase(iNOS) and astrocyte activation pathway signaling and activators of transcription(STAT3). The activity of astrocytes was detected by CCK-8. RT-qPCR and ELISA were used to assay the expression of the core protein of CSPG(aggrecan and versican). Results: In vivo experiments showed that the expression of GFAP and CSPG in the spinal cord injury area in LLLT group was lower than that in SCI group(P<0.05). The results of in vitro experiments showed that the expression of iNOS in macrophages significantly decreased(P<0.05) after LLLT. The activity of astrocytes in M1 group was significantly increased, compared with the Ctrl group(P<0.05), and the expression of pSTAT3/STAT3 significantly increased(P<0.05). Compared with M1 group, the activity of astrocytes in M1+LLLT group significantly decreased(P<0.05), and the expression of pSTAT3 was significantly inhibited(P<0.05). RT-qPCR and ELISA showed the expression of aggrecan and versican mRNA and protein in M1 group was significantly higher than that in Ctrl group(P<0.05). Compared with M1 group, the experession of aggrecan mRNA and protein in M1+LLLT group was inhibited(P<0.05). However, while the protein expression of versican decreased, but there was no statistical difference. Conclusions: Low level laser therapy can inhibit the activation of astrocytes and reduce the expression of CSPG in the spinal cord injury region of SCI mice, which can be achieved by macrophages under low level laser.