Cytokine signatures associate with disease severity in children with Mycoplasma pneumoniae pneumonia

Abstract

Host immune response may be involved in the pathogenesis of children Mycoplasma pneumoniae pneumonia (MPP). In the current study, we investigated the alterations of cytokines levels among control, mild MPP and severe MPP children to determine whether cytokine signatures associate with MPP and correlate with disease severity. We measured 13 cytokines in bronchoalveolar lavage fluid (BALF) of 88 children with MPP and 26 children with foreign body aspiration (FB) using a Luminex system. Linear discriminant analyses were performed to develop predictive models of mild MPP and severe MPP on these children. We observed nearly complete separations of severe MPP group, mild MPP group and control group in linear discriminant analyses. Eleven cytokines significantly increased in children with MPP, and seven cytokines had statistically significant upward linear trends correlated with MPP severity. In addition, compared to control group, both IFNγ/IL4 ratio and IFNγ/IL13 ratio increased in mild MPP and severe MPP groups. Our results suggest that children MPP can alter BALF cytokines signatures which associate with disease severity and can be characterized by a distinct airway molecular phenotype that has elevated Th1/Th2 ratios.

Figure 1

Linear discriminant analysis results. (a) Scatterplot of the discriminant functions generated from 13 factors. Each data point represents a single BALF sample. The plot depicts clustering and clear separation of severe MPP children (red square), mild MPP children (green triangles) and FB children (blue circles). Dark blue diamond represents group centroid. (b) Classified accuracy of the original grouped cases and cross-validated grouped cases were shown as well.

Figure 2

Analysis of the expression levels of TNFα, IL6, IL1β, MCP1, IL4, IFNγ and IL10 in BALF. (a) Cluster analysis results showing representative expression patterns in each group. (b) Diagram of protein protein interaction (PPI) network showing the evidence of the relationships among the proteins. The known or predicted 3d structure of the protein was shown inside the circles. The types of interaction evidence were indicated as below: yellow line represents the text mining evidence; black line represents the co-expression evidence and purple line represents the experimental evidence. (c) Diagram of PPI network showing type of interactions among the proteins. Arrow line represents positive action, T-type line represents negative action and round head line represents unspecified action. Yellow line means transcriptional regulation, red line means inhibition, blue line means binding and gray line means reaction.

Figure 3

The analysis of Th1/Th2 ratios in MPP children. (a) Model diagram showing Th cell differentiation. (b) The ratios of IFNγ/IL4 in control, mild MPP and severe MPP groups. (c) The ratios of IFNγ/IL4 in control group and MPP group. (d) The ratios of IFNγ/IL13 in control, mild MPP and severe MPP groups. (e) The ratios of IFNγ/IL13 in control group and MPP group. The results of Benjamini-Hochberg adjusted p were shown as: *padj < 0.05, **padj < 0.01, ***padj < 0.001.

Figure 4

mRNA levels of IFNγ, IL4, IL13, T-bet and Gata3 in BALF of children with MPP. (a) mRNA levels of IFNγ in control, mild MPP and severe MPP groups. (b) mRNA levels of IL4 in control, mild MPP and severe MPP groups. (c) mRNA levels of IL13 in control, mild MPP and severe MPP groups. (d) The ratios of IFNγ/IL4 in control, mild MPP and severe MPP groups. (e) The ratios of IFNγ/IL13 in control, mild MPP and severe MPP groups. (f) mRNA levels of IFNγ in control and MPP groups. (g) mRNA levels of IL4 in control and MPP groups. (h) mRNA levels of IL13 in control and MPP groups. (i) The ratios of IFNγ/IL4 in control and MPP groups. (j) The ratios of IFNγ/IL13 in control and MPP groups. (k) mRNA levels of T-bet in control, mild MPP and severe MPP groups. (l) mRNA levels of Gata3 in control, mild MPP and severe MPP groups. (m) The ratios of T-bet/Gata3 in control, mild MPP and severe MPP groups. (n) mRNA levels of T-bet in control and MPP groups. (o) mRNA levels of Gata3 in control and MPP groups. (p) The ratios of T-bet/Gata3 in control and MPP groups. p values were shown as: *p < 0.05, **p < 0.01, ***p < 0.001.