Suppressive Effect Of Galectin-1 Secreted From Bone Marrow-derived Mesenchymal Stem Cells On Airway Inflammation In Asthma

Objective: This study aimed to investigate the effect on airway remodeling and airway inflammation by administrating mesenchymal stem cells(MSCs)in ovalbumin-induced asthmatic mice and the underlying mechanism for the sake of providing given guide in asthma treatment.Methods:(1)To isolate,culture and identificate of MSCs or dendritic cells(DCs)derived from male BALB/c mice.(2)Mice were sensitized and challenged with ovalbumin(OVA)to establish asthmatic mice model.MSCs were administered into tail vein of mice.Mice in each group as following: PBS group,PBS+ MSCs group,asthma group and asthma+MSCs group.Lung histologic HE staining and PAS staining,total cell count and differential cell count of BALF,interleukin(IL)-10,IL-12 and Galectin-1(Gal-1)assay of serum and BALF,were used for estimating the effect of MSCs inhibition on airway inflammation.Real-time PCR and Western blot detected the expression of Gal-1 in lung of each group.(3)MSCs and DCs derived from mouse bone marrow were co-cultured using Transwell culture plates under different in vitro culture conditions.Effect of MSCs on DC phenotype was detected by flow cytometry.IL-10,IL-12,and Gal-1 levels in the co-culture supernatants were measured by enzyme-linked immunosorbent assay.Mixed lymphocyte reaction assay detected the effect of MSCs on the proliferative activity of DCs.(4)In some experiments,Gal-1 inhibitor isopropyl ?-D-1-thiogalactopyranoside(IPTG)was added directly to the DCs medium.Effect of MSCs on DC phenotype was detected by flow cytometry.IL-10,IL-12,and Gal-1 levels in the co-culture supernatants were measured by enzyme-linked immunosorbent assay.Mixed lymphocyte reaction assay detected the effect of MSCs on the proliferative activity of DCs.Real-time PCR and Western blot detected the expression of Gal-1 in DCs of each group.Immunofluorescence detected differential expression of Gal-1 on the surface of DCs.(5)The phosphorylation of ERK?p38 MAPK and JNK in DC were detected.Then,the ERK inhibitor PD98059,p38 MAPK inhibitor SB203580,or JNK inhibitor SP600125 was used to inhibit the MAPK signaling pathway in DC,followed by Gal-1expression detection.Results:(1)Bone marrow-derived MSCs administration significantly alleviated airway inflammation and airway remodeling of asthmatic mice.MSCs significantly elevated level of IL-10,IL-12 and Gal-1 in serum and BALF of mice.MSCs also elevated level of Gal-1protein in lung.(2)This study showed that co-culture of MSCs and DCs in vitro inhibited the effect of DCs on T cell proliferation by downregulating the expression of co-stimulatory molecules such as CD80,CD86,CD83 and MHC II on the surface of DCs.The present study also showed that after co-culturing MSCs with DCs,the level of IL-10,IL-12 and Gal-1 in the culture supernatants increased with the increase in MSCs concentration.(3)When Gal-1 inhibitor IPTG was added to the MSC + DC group,the expression of co-stimulatory molecules on the surface of DCs was significantly increased,the proliferation of allogeneic T cells stimulated by DCs was significantly increased,and the levels of IL-10 and IL-12 in the supernatant was significantly lower than those of the MSC + DC and Gal-1 + DC groups,suggesting that MSCs might play their inhibitory role through Gal-1.Therefore,our study indicated that the Gal-1 secreted from MSCs could upregulate the expression of Gal-1 on DCs,which is the first reported so far.(4)Gal-1 activates the ERK pathway and inhibits the p38 MAPK pathway in DCs.After adding the Gal-1 inhibitor IPTG,contradictory results were obtained.MAPK inhibitor administration confirmed that Gal-1 might inhibit DCs via MAPK signaling pathway in DCs.Conclusion: Bone marrow-derived MSCs administration alleviates airway inflammation and airway remodeling of asthmatic mice by secreting Gal-1,which activates the ERK pathway,inhibits the p38 MAPK pathway in DCs,and increases the IL-12 and IL-10 levels,thereby conferring DCs with the potential of induced tolerance,directly inhibiting the proliferation and activation of T cells and alleviating airway inflammation of asthma.