THE CHANGE OF PERIPHERAL TH22 CELLS AND PLASMA INTERLEUKIN-22 IN CHILDREN WITH MYCOPLASMA PNEUMONIAE PNEUMONIA

Kunxia Li^{1, #}, Haiyan Xing^{2, #}, Aimin Li¹, Hong Yan¹, Yanqiu Wu^{1, *}, Jianyong Wang^{1, *}

¹Department of Pediatrics, The Affiliated Yantai Yuhuangding Hospital of Qingdao University. Yantai, Shandong 264000, P.R. China  ²Department of Allergy, The Affiliated Yantai Yuhuangding Hospital of Qingdao University. Yantai, Shandong 264000, P.R. China 

Objective: The aim of this study is to investigate the involvement of Th22 cells and IL-22 in the pathogenesis of childhood Mycoplasma pneumoniae pneumonia (MPP).

Method: This study involved 32 healthy control (HC) and 75 pediatric patients including 45 patients with general MPP (GMPP) and 30 patients with refractory MPP (RMPP). The frequency of peripheral Th22 cells was examined by flow cytometry. The concentrations of plasma cytokines were measured by enzyme-linked immunosorbent assay (ELISA). Transcription factor AHR mRNA levels were quantified by reverse transcription-quantitative polymerase chain reaction (RT-qPCR).

Results: The Th22 cells percentage and expression levels of AHR and IL-22 in peripheral blood were all significantly elevated in MPP patients compared with the healthy controls. Furthermore, we found a significantly higher percentage of Th22 cells and levels of AHR and IL-22 in children with RMPP, compared with children with GMPP. In addition, higher tumor necrosis factor-α (TNF-α) and IL-6 levels were observed in children with MPP, especially in RMPP group.

Conclusion: The expansion of the Th22 cells subset and the increased secretion of the IL-22 cytokine may contribute to the progression of childhood MPP, while its excessive response may be associated with the development of childhood RMPP.