广西医学

目的探讨不同病原体感染肺炎患儿血清中性粒细胞胞外诱捕网（NETs）与维生素D水平之间的相关性。方法选取80例肺炎患儿作为研究组，根据致病病原体类型分为肺炎支原体感染组（n=40）、流感病毒感染组（n=22）、肺炎支原体与流感病毒混合感染组（混合感染组，n=18）。另选取健康儿童作为对照组（n=20）。收集各组的一般资料及炎症指标检测结果。测定各组血清25-羟基维生素D3［25（OH）D3］、髓过氧化物酶⁃DNA复合物（MPO⁃DNA）、细胞游离DNA（cf⁃DNA）水平。评估血清MPO⁃DNA、cf⁃DNA水平与血清25（OH）D3水平之间的相关性。结果混合感染组的发热时间、总病程、白细胞计数（WBC）、中性粒细胞百分比（NE%）、血清C反应蛋白（CRP）和白细胞介素（IL）⁃6水平长于或高于肺炎支原体感染组和流感病毒感染组，肺炎支原体感染组的上述指标长于或高于流感病毒感染组（P<0.05）；肺炎支原体感染组、流感病毒感染组及混合感染组的WBC、NE%、血清CRP和IL⁃6水平高于对照组（P<0.05）。肺炎支原体感染组、流感病毒感染组及混合感染组的血清25（OH）D3水平低于对照组，混合感染组的血清25（OH）D3水平低于肺炎支原体感染组和流感病毒感染组，肺炎支原体感染组的血清25（OH）D3水平低于流感病毒感染组（P<0.05）；肺炎支原体感染组、流感病毒感染组及混合感染组的血清cf⁃DNA和MPO⁃DNA水平高于对照组，混合感染组的血清cf⁃DNA和MPO⁃DNA水平高于肺炎支原体感染组和流感病毒感染组，肺炎支原体感染组的血清cf⁃DNA水平高于流感病毒感染组，流感病毒感染组的血清MPO⁃DNA水平高于肺炎支原体感染组（P<0.05）。相关性分析结果显示，研究组肺炎患儿血清cf⁃DNA、MPO⁃DNA水平与血清25（OH）D3水平呈负相关（P<0.05）；肺炎支原体感染组、混合感染组的血清cf⁃DNA、MPO⁃DNA水平与血清25（OH）D3水平呈负相关（P<0.05）；流感病毒感染组的血清cf⁃DNA、MPO⁃DNA水平与血清25（OH）D3水平无相关性（P>0.05）。结论在肺炎支原体肺炎患儿中，血清MPO⁃DNA、cf⁃DNA水平与血清25（OH）D3水平呈负相关，提示维生素D可能在肺炎支原体肺炎免疫反应中发挥调节作用。

Objective To investigate the correlation between serum neutrophil extracellular traps (NETs) level and vitamin D level in children with pneumonia infected by different pathogens. Methods A total of 80 children with pneumonia were enrolled as the study group, and they were assigned to Mycoplasma pneumoniae infection group (n=40), influenza virus infection group (n=22), or Mycoplasma pneumoniae and influenza virus infection group (mixed infection group, n=18) according to pathogen type. In addition, healthy children were selected as the control group (n=20). General data and test results of inflammatory indices were collected for each group. Serum levels of 25‑hydroxy vitamin D₃ (25［OH］D₃), myeloperoxidase‑DNA complex (MPO‑DNA), and cell‑free DNA (cf‑DNA) were measured in various groups. Correlation between serum MPO‑DNA, cf‑DNA, and 25(OH)D₃ levels were evaluated. Results The mixed infection group exhibited longer fever duration and total disease course, as well as higher white blood cell counts (WBC), neutrophil percentage (NE%), and serum C‑reactive protein (CRP) and interleukin (IL)‑6 levels as compared with the Mycoplasma pneumoniae infection group and the influenza virus infection group, whereas the Mycoplasma pneumoniae infection group interpreted longer or higher indices as above as compared with the influenza virus infection group (P<0.05). WBC, NE%, and serum levels of CRP, and IL‑6 of the Mycoplasma pneumoniae infection group, the influenza virus infection group, and the mixed infection group were higher than those of the control group (P<0.05). Serum 25(OH)D₃ level of the Mycoplasma pneumoniae infection group, the influenza virus infection group, and the mixed infection group was lower than that of the control group; moreover, the mixed infection group depicted a lower serum 25(OH)D₃ level as compared with the Mycoplasma pneumoniae infection group and the influenza virus infection group, and the Mycoplasma pneumoniae infection group expressed a lower serum 25(OH)D₃ level as compared with the influenza virus infection group (P<0.05). Serum cf‑DNA and MPO‑DNA levels of the Mycoplasma pneumoniae infection group, the influenza virus infection group, and the mixed infection group were higher than those of the control group; furthermore, the mixed infection group yielded higher serum cf‑DNA and MPO‑DNA levels as compared with the Mycoplasma pneumoniae infection and influenza virus infection groups, as well as the Mycoplasma pneumoniae infection group indicated a higher serum cf‑DNA level as compared with the influenza virus infection group, and the influenza virus infection group had a higher serum MPO‑DNA level than the Mycoplasma pneumoniae infection group (P<0.05). Correlation analysis results revealed that serum cf‑DNA and MPO‑DNA levels negatively correlated with serum 25(OH)D₃ level in the study group, and this negative correlation was also observed in the Mycoplasma pneumoniae infection and mixed infection groups (P<0.05), but no correlation between serum cf⁃DNA and MPO⁃DNA levels was observed in the influenza virus infection group (P>0.05). Conclusion Serum MPO‑DNA and cf‑DNA levels negatively correlate with serum 25(OH)D₃ level in children with Mycoplasma pneumoniae pneumonia, suggesting that vitamin D may play a regulatory role in the immune response in Mycoplasma pneumoniae pneumonia.