The clinical significance of spondin 2 eccentric expression in peripheral blood mononuclear cells in bronchial asthma

Abstract

Background: Bronchial asthma (BA) was a heterogeneous disease characterized by chronic airway inflammation. Spondin 2 (SPON2) was reported to be implicated in the integrin pathway, protein metabolism, and drug-induced lupus erythematosus. The purpose of this study was to evaluate the significance of SPON2 in BA diagnosis and treatment.

Methods: Peripheral blood samples were obtained from 137 BA pediatric patients (61 mild-to-moderate BA and 76 severe BA) and 59 healthy children. Subject's information, clinical indexes, pulmonary ventilation functions were recorded in the two groups. Peripheral blood mononuclear cells (PBMCs) were isolated from patients' samples. qRT-PCR and ELISA assays were employed to examine the levels of SPON2 and inflammatory cytokines, respectively. Pearson's correlation analysis confirmed the association between SPON2 and inflammatory cytokines. Receiver operating characteristic (ROC) analysis was used to evaluate the potentials of SPON2 in terms of BA detection and discriminating against the severity of BA.

Results: Bioinformatics analysis showed that SPON2, OLFM4, XIST, and TSIX were significantly upregulated, while KDM5D and RPS4Y1 were reduced in BA. GO analysis verified that these six genes were mainly involved in neutrophil degranulation, neutrophil activation involved in immune response, neutrophil activation, and neutrophil-mediated immunity. After isolating PBMCs, we found that SPON2 was remarkably increased in BA pediatric group compared with healthy children, and the relative levels of SPON2 were related to the severity of BA. The receiver operating characteristic (ROC) analysis revealed the high potentials of SPON2 in BA diagnosis (AUC was 0.8080) and severity distinctions (AUCs were 0.7341 and 0.8541, respectively). Also, we found that there were significant differences in fractional exhaled nitric oxide (FeNO), forced expiratory volume in 1 s (FEV1)%, FEV1/ forced vital capacity (FVC)%, immunoglobulin E (IgE), serum eosinophils, and serum neutrophils between mild-to-moderate BA group and severe BA group. Finally, SPON2 was negatively correlated with IL-12 while positively associated with IL-4, IL-13, and IL-17A.

Conclusions: SPON2 was a viable biomarker for diagnosing and degree of severity in BA, providing more insight into exploring BA and treatment's pathogenesis.

Keywords: GO analysis; bronchial asthma; diagnosis; peripheral blood mononuclear cell; spondin 2.

FIGURE 1

The functions of differentially expressed genes in BA. (A) Volcano plot of differentially expressed genes in BA. x‐axis: log₂(fold change), y‐axis: ‐log₁₀(adjusted p value). (B) GO analysis of differentially expressed genes in BA, including biological processes, cellular components, and molecular functions. BA, bronchial asthma

FIGURE 2

Confirmation of eccentric expressions of SPON2 in PBMCs from BA patients and healthy volunteers. (A) Levels of SPON2 were prominently increased in the healthy group. (B) Levels of SPON2 were higher in the severe group compared with the mild‐to‐moderate group. PBMC, peripheral blood mononuclear cell; SPON2, defensin alpha 4; healthy, healthy volunteers; BA, bronchial asthma

FIGURE 3

Expressions of IL‐4, IL‐12, IL‐13, and IL‐17A in BA patients and their relationship with SPON2 expression. (A‐D) Levels of IL‐4, IL‐12, IL‐13, and IL‐17A were abnormally expressed in BA patients compared with healthy controls. (E‐H) Pearson's correlation analysis measured the correlation between SPON2 and IL‐4, IL‐12, IL‐13, and IL‐17A expressions. SPON2, defensin alpha 4; healthy, healthy volunteers; BA, bronchial asthma

FIGURE 4

ROC analysis of SPON2 in BA. (A) The AUC of SPON2 concerning discriminating BA patients from healthy controls. (B) The AUC of SPON2 concerning mild‐to‐moderate BA patients from healthy controls. (C) The AUC of SPON2 concerning severe BA patients from healthy controls. ROC, receiver operating characteristic; AUC, area under the curve; SPON2, defensin alpha 4; healthy, healthy volunteers; BA, bronchial asthma