Elastin peptides modulate T helper response during murine emphysema

Abstract

Introduction: COPD-associated inflammatory process is characterized by the secretion of proteases by lung-infiltrating inflammatory cells that promote breakdown of elastin. In a recent work, we reported that in mice elastin peptides (EP), i.e. the VGVAPG hexapeptide, are potent inducers of lesions similar to that observed in porcine pancreatic elastase (PPE) mouse model of emphysema. Also of interest, it has been shown that EP could influence T cell polarization. Objective: The orientation of the T helper response (Th1/Th2/Th17) during COPD physiopathology remains controversial. The aim of our work is to investigate in mice the role of EP in the polarization of CD4 + T lymphocytes during emphysema. Methods: C57BL/6 mice were intratracheally instilled with PBS, PPE or VGVAPG. After 21 days, mice were euthanized. Lungs, mediastinal lymph nodes and spleen were harvested and CD4 + T cells were stimulated. T cell phenotype was analyzed by multicolor flow cytometry including intracellular staining of cytokines (IFNγ, IL4, IL17a) and associated transcription factors (Tbet, Gata3, RoRγT, Foxp3). The amounts of secreted cytokines by stimulated CD4 + T cells were assessed by Cytometric Bead Array. Results: Both instillation of PPE and VGVAPG significantly increased the proportion of activated Th1 and Th17 CD4 + CD25 + T cells without any discernible effect on the proportion of Th2 cells. This polarization was maximized when CD4 + T cells were challenged ex vivo in the presence of VGVAPG or a mixture of EP. Conclusion: Our results clearly suggest that during murine emphysema CD4+ T cells are polarized toward a Th1 and Th17 phenotypes and that EP are key factors to induce and reinforce inflammatory process.