Immunosuppression Reduces Lung Injury Caused by Mycoplasma pneumoniae Infection

Shuang Shi,Yao Zhou,Heng Tang,Deyu Zhao,Feng Liu,Xiuqing Zhang

doi:10.1038/s41598-019-43451-9

Abstract

The underlying mechanisms of Mycoplasma pneumoniae pneumonia (MPP) pathogenesis are not clearly understood. This study aimed to investigate the correlation between immune response and lung injury in MPP. The clinical characteristics of MPP were compared between patients treated with and without immunosuppressive chemotherapy, and demographic, clinical, and laboratory data were compared between patients with severe and mild MPP. To determine the effect of immune response on lung lesions, mouse MPP and immunosuppression models were established by intranasal inoculation of M129 and intraperitoneal injection of cyclophosphamide, respectively. Myeloperoxidase and oxidant–antioxidant enzyme activities were evaluated for mechanism studies. The immunosuppressant group had a lower incidence of MPP and fewer cases of severe MPP than the non-immunosuppressant group. The severe MPP group had a greater incidence of severe immune disorders than the mild MPP group. Relative to immunosuppressed mice, wild mice exhibited more severe inflammatory infiltration and lung injury as well as a significant increase in myeloperoxidase and malondialdehyde levels and a decrease in superoxide dismutase level after MP infection. In conclusion, immunological responses likely play a vital role in MPP pathogenesis. Lung injury occurring after MP infection—which might be caused by oxidant–antioxidant imbalance—can be reduced by immunosuppression.

Highlights

Mycoplasma pneumoniae (MP), a common pathogen of community-acquired pneumonia in children and adolescents, accounts for 10–40% of cases of community-acquired pneumonia in children
We aimed to explore the relationship between immune response and lung injury after MP infection by comparatively analyzing the clinical data of Mycoplasma pneumoniae pneumonia (MPP) from patients who received treatment with and without immunosuppressants and by comparing clinical data between patients with mild and severe MPP between January 1 and December 31, 2016
The immunosuppressant group had a lower incidence of MPP than the non-immunosuppressant group

Summary

Introduction

Mycoplasma pneumoniae (MP), a common pathogen of community-acquired pneumonia in children and adolescents, accounts for 10–40% of cases of community-acquired pneumonia in children It can cause MP pneumonia (MPP) and a variety of extra-pulmonary multiple systemic complications. Relevant studies have suggested that aggravation of MPP is related to abnormal immune response[1], macrolide resistance[2], increase in MP copy number[3], and co-infection with other pathogens[4]. An increasing number of studies have reported that immune response acts as a double-edged sword, playing an antibacterial role in the early stages of infection and causing tissue damage as a persistent effect in many types of bacterial infection[7]. Lai et al.[12] have confirmed that neutrophils are not essential for www.nature.com/scientificreports/

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