Detection of the levels of neuropeptides, ACTH and cortisol in the blood of patients with polymyositis/dermatomyositis and their significance.

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Recent research has shown that the neuroendocrine system can regulate the function of the immune system and that ACTH and cortisol play important roles in maintaining the immune homeostasis. Polymyositis and dermatomyositis (PM/DM) are autoimmune diseases with unclear pathogeneses closely related with immune disorders, so we detected the levels of neuropeptide Y (NPY), beta-endorphin (beta-EP), calcitonin gene-related peptide (CGRP), adrenocoricotropic hormone (ACTH), and cortisol in blood of patients with PM/DM to investigate the relationship between these indices and the pathogenesis of PM/DM. The detection of NPY, beta-EP, CGRP, and ACTH concentrations in plasma and cortisol in serum of 28 cases of PM/DM was carried out using radioimmunoassay methods, and the results were compared with those of 20 normal controls. The levels of NPY in the plasma of PM/DM was significantly higher than those of the controls, while beta-EP, CGRP and ACTH were significantly lower than those of the controls, and cortisol was not significantly different before treatment. Linear correlation analysis indicated that NPY was significantly positively correlated with CPK, and beta-EP and CGRP were significantly negatively correlated with CPK. There were no significant correlations among cortisol ACTH, and CPK and no significant correlations between NPY, beta-EP, CGRP, ACTH, cortisol and age or duration of disease before treatment. After treatment for three months, NPY, beta-EP and CGRP tended to become normal and no longer significantly different from the control values. However, ACTH fell further and was significantly lower than the level before treatment. Therefore the increase in NPY and the decreases in beta-EP, CGRP, and ACTH in the plasma of PM/DM patients may be related to the pathogenesis of PM/DM.