Abstract: Objective To investigate the changes in peripheral blood and monocyte-derived high mobility group protein B1 (HMGB1) levels in patients with non-puerperal mastitis (NPM) and their correlation with the disease. Methods A total of 83 patients with NPM were divided into the acute group (42 cases) and the chronic group (41 cases) according to their conditions Additionally, 40 healthy subjects were taken as the control group. The levels of HMGB1, C-reactive protein (CRP), and interleukin-6 (IL-6) in the peripheral blood of each group were detected by ELISA. The number of monocytes and the level of HMGB1 were detected by flow cytometry; the expression of HMGB1 in monocytes was detected by qPCR and Western blot; the correlation between the expression of HMGB1 in monocytes and the levels of CRP and IL-6 in peripheral blood was analyzed by the Pearson method. ROC curves were constructed to evaluate the diagnostic value of HMGB1 expression level in monocytes for the condition of NPM. Results The levels of HMGB1, CRP, IL-6 in the peripheral blood of patients with NPM, the number of M1-type monocytes and the HMGB1 mRNA expression in monocytes were all higher than those in the control group. Meanwhile, these levels in the acute group were higher than those in the chronic group (P＜0.05). The level of HMGB1 mRNA in monocytes was positively correlated with CRP (r=0.426) and IL-6 (r=0.569) in peripheral blood (all P＜0.05). The AUC of HMGB1 protein level in M1 monocytes for diagnosing NPM was 0.739 (95% CI: 0.67-0.82), the sensitivity and specificity were 69.8% and 77.2%. The AUC for evaluating the disease condition was 0.828 (95% CI: 0.73-0.91), the sensitivity and specificity were 83.3% and 71.4%. Conclusions The expression of HMGB1 in monocytes of patients with NPM increases and is positively correlated with the levels of peripheral blood CRP and IL-6, which is helpful for the diagnosis and condition assessment of NPM.

Key words: non-puerperal mastitis, monocyte, high mobility group protein B1, diagnosis