Department of Infectious Disease, Children's Hospital of Soochow University, Suzhou, 215003, China.
Department of Respiratory Disease, Children's Hospital of Soochow University, Suzhou, 215003, China.
BMC Infect Dis. 2018 Aug 29;18(1):439. doi: 10.1186/s12879-018-3346-8.
Increasing numbers of refractory or severe, even fatal, cases of Mycoplasma pneumoniae infections have been reported in recent years. Excessive inflammatory responses play a vital role in the pathogenesis of refractory M. pneumoniae pneumonia (RMPP). HMGB1 is an actively secreted cytokine produced by macrophages and other inflammatory cells that participates in various infectious diseases. The present study aimed to explore the role and clinical significance of HMGB1 in children with RMPP and the potential mechanism of HMGB1 expression.
Four hundred and fifty-two children diagnosed with M. pneumoniae pneumonia, including 108 children with RMPP, were enrolled from January 2013 to December 2015 at the Children's Hospital of Soochow University. HMGB1, TNF-α, and IL-6 in peripheral blood from RMPP and non-RMPP (NRMPP) cases were detected by real-time PCR and ELISA. Lipid-associated membrane proteins (LAMPs) were extracted from live M. pneumoniae and prepared at different concentrations for stimulation of THP-1 cells. After coculture with LAMPs, HMGB1, TNF-α, IL-6, RAGE, TLR2, and TLR4 in THP-1 cells were detected by real-time PCR.
Occurrences of cough, fever, and abnormal lung signs were more frequent in RMPP cases compared with NRMPP cases (all p < 0.05). Children with RMPP had longer hospital stays than children with NRMPP (p < 0.05). Different distributions of lymphocytes were noted between RMPP and NRMPP cases. HMGB1, TNF-α, and IL-6 levels were significantly higher in RMPP cases compared with NRMPP cases (all p < 0.05). HMGB1 had good diagnostic ability to differentiate RMPP with AUC of 0.876, sensitivity of 0.833, and specificity of 0.824 compared with TNF-α and IL-6. HMGB1 expression in THP-1 cells was increased by stimulation with 10 μg/ml LAMPs. TLR2 expression was increased after stimulation with 6 μg/ml LAMPs. HMGB1 level was positively associated with TNF-α, IL-6, and TLR2 levels.
HMGB1 is a good diagnostic biomarker for differentiating RMPP and NRMPP. LAMPs from M. pneumoniae may induce HMGB1 expression in immune cells through the TLR2 pathway. Further in vitro and in vivo studies are needed for the development of a new treatment strategy to inhibit the HMGB1 pathway, thereby preventing the inflammation in RMPP.
近年来，越来越多的难治性或严重的甚至致命的肺炎支原体感染病例被报道。过度的炎症反应在难治性肺炎支原体肺炎（RMPP）的发病机制中起着至关重要的作用。HMGB1 是一种由巨噬细胞和其他炎症细胞主动分泌的细胞因子，参与各种传染病的发生。本研究旨在探讨 HMGB1 在儿童 RMPP 中的作用和临床意义及其表达的潜在机制。
2013 年 1 月至 2015 年 12 月，苏州大学儿童医院共收治 452 例肺炎支原体肺炎患儿，其中难治性肺炎支原体肺炎 108 例。采用实时 PCR 和 ELISA 检测 RMPP 和非难治性肺炎支原体肺炎（NRMPP）患儿外周血中 HMGB1、TNF-α 和 IL-6 的水平。从活肺炎支原体中提取脂相关膜蛋白（LAMPs），并以不同浓度制备，用于刺激 THP-1 细胞。与 LAMPs 共培养后，采用实时 PCR 检测 THP-1 细胞中 HMGB1、TNF-α、IL-6、RAGE、TLR2 和 TLR4 的表达。
与 NRMPP 患儿相比，RMPP 患儿咳嗽、发热和肺部异常体征的发生率更高（均 p<0.05）。RMPP 患儿的住院时间长于 NRMPP 患儿（p<0.05）。RMPP 与 NRMPP 患儿的淋巴细胞分布不同。与 NRMPP 患儿相比，RMPP 患儿的 HMGB1、TNF-α 和 IL-6 水平明显升高（均 p<0.05）。HMGB1 对 RMPP 的诊断能力较好，AUC 为 0.876，敏感性为 0.833，特异性为 0.824，优于 TNF-α和 IL-6。用 10μg/ml LAMPs 刺激后，THP-1 细胞中 HMGB1 的表达增加。用 6μg/ml LAMPs 刺激后，TLR2 的表达增加。HMGB1 水平与 TNF-α、IL-6 和 TLR2 水平呈正相关。
HMGB1 是鉴别 RMPP 和 NRMPP 的良好诊断生物标志物。肺炎支原体的 LAMPs 可能通过 TLR2 途径诱导免疫细胞中 HMGB1 的表达。需要进一步的体外和体内研究来开发一种新的治疗策略来抑制 HMGB1 途径，从而防止 RMPP 中的炎症。
