The Immunological Significance And The Expression Of Negative Costimulatory Molecule PD-1 In Patients With Myasthenia Gravis

Myasthenia gravis (MG) is an antigen-specific antibody (Ab)-mediated autoimmune disease , which affects the function of the neuromuscular junction (NMJ) postsynaptically. Resent years, it has been reported that, CD4 + T cells and cytokines play important regulatory roles in the pathogenesis of MG. There are several varieties of immune-related factors involved in MG, the autoimmune diseases, the imbalance of the immune system plays an important role in the pathogenesis of MG.The two-signal theory for T cell activation provides a new gate way for immune balance rebuilding studies. More and more attention has been payed to the role of the costimulatory molecule in the field of immune regulation, and the negative costimulatory molecules have become a research hotpoint. As one of the most important negative costimulatory molecule, PD-L1 (programmed death ligand L1) /PD-1 (programmed death 1) signaling pathway is thought to deeply involved in the field of transplant rejection, autoimmune diseases, chronic viral infections, cancer and other immune related diseases. In this study, We detected the expression of PD-1 and PD-L1 on the peripheral blood monomuclear cells of MG patients and normal control, as well as solubale PD-1 in the sera of these population.Part 1 The expression of PD-L1 and PD-1 on peripheral blood mononuclear cells from patients with myasthenia gravisObjective: To explore the relationship between CD4~+T cells, mononuclear cells and the pathogenesis of MG, by detecting the preportion of CD4~+-PD-1+T cell and CD14~+-PD- L1+ cell in peripheral blood mononuclear cells from myasthenia gravis patients. Methods: Peripheral blood were collected from 45 cases of MG patients and 33 healthy persons. The expression of PD-1 and PD-L1 on peripheral blood mononuclear cells were detected using immuno-fluorescence staining and flow cytometry. Results①The expression of PD-1 on CD4 + T cells from MG patient PBMC is higher than that from the health controls.②The expression of PD-L1 + was increased on CD14 + cells from MG group comparing with that from the control group.③There was a significant increase of the expression of PD-1 on CD4~+ T cells from the MG patients with Thymoma comparing with those MG patients without Thymoma.④The expression of PD-L1 in the MG patients with Thymoma or hyperplasia decreased obviously comparing with that of the patients with normal thymus.⑤As well as that in the Early-onset MG (age<40) comparing with that of the late-onset MG group (age≥40).. Conclusion: the increased expressions of PD-1 and PD-L1 on the PBMCs from MG patients suggesting the involvement of the couple of molecules in the pathological procedure of MG and MG might be an age-related disease.Part II Quantification of soluble PD-1(sPD-1) in serum from MG patients Objective: To look for a possible laboratory reference of MG, as well as to provide a theoretical basis for the treatment of MG in future, the concentrations of soluble PD-1 from the serum of MG patients were detected.Methods: The serum from the MG patients and healthy controls were collected by certifuging the blood from the samples as mentioned above.The concentration of sPD-1 was measured using an ELISA kit.Results:①The concentration of sPD-1 was elevated in the same serum specimens from the MG patients comparing with the healthy controls.②The concentration of sPD-1 in the Early-onset MG group (age<40) was significantly higher than that of the Late-onset MG group(age≥40) .Conclusion: Higher concentration of soluble PD-1 in the serum of patients with MG suggests that sPD-1 might involve in the pathological procedure of MG, and it might disturb the ligation of PD-1 and PD-L1, which might result in the abnormal translation of negative modulating signal, and accelarate the pathological precedure of MG.