Heparin-binding epidermal growth factor-like growth factor (HB-EGF) activates p38 to affect pulmonary fibrosis

Abstract

Objective

We aimed to examine whether heparin-binding epidermal growth factor-like growth factor (HB-EGF) affects the lung fibrosis process through the activation of p38 protein in mitogen-activated protein kinases (MAPK) signaling pathway, as well as the expression of downstream inflammatory factors.

Methods

The expression levels of HB-EGF, collagen type I (COL-I), and hexokinase 2 (HK2) in peripheral blood mononuclear cells (PBMCs) of patients with connective tissue disease-related interstitial lung disease (CTD-ILD) were examined by qPCR, Western blotting and ELISA.

Results

In vitro experiments showed that HB-EGF was increased in almost all subtypes [rheumatoid arthritis (RA), systemic sclerosis (SSc) and idiopathic inflammatory myopathies (IIMs)] as well as in all groups (P < 0.05). For embryonic lung fibroblast (A549) cells, the expression levels of HK2 and α-smooth muscle actin (α-SMA) genes were elevated during 0–4 h and then plateaued. Transforming growth factor-β1 (TGF-β1) induced fibrosis in human embryonic lung fibroblasts (MRC-5) cells and A549 for a certain period of time, but the degree of induction varied, which may be related to the redifferentiability of cells at different spatial locations. Moreover, HB-EGF at concentrations above 1 ng/ml stimulation increased COL-I expression (P < 0.05), and for α-SMA gene, even 1 ng/ml concentration of HB-EGF had a stimulatory effect, and different concentrations of HB-EGF did activate the expression of p38 in a concentration-dependent manner within a certain concentration range, and by The qPCR results showed that for interleukin 6 (IL-6), an inflammatory factor regulated downstream of p38, the expression was significantly increased in A549 cells compared to control (P < 0.05), but tumor necrosis factor-α (TNF-α) expression was downregulated (P < 0.05), but for interleukin-1β (IL-1β) gene, there was no significant difference in A549 cells, and expression was downregulated in MRC-5 cells. Therefore, it is suggested that HB-EGF regulates the expression of inflammatory factors through p38 will be differential across cells.

Conclusion

Our study shows that HB-EGF can suppress pulmonary fibrosis through downstream activation of p38/MAPK pathway activity, as well as the expression of various inflammatory factors downstream of it.