IL-33 and Superantigenic Activation of Human Lung Mast Cells Induce the Release of Angiogenic and Lymphangiogenic Factors

Abstract

Human lung mast cells (HLMCs) express the high-affinity receptor FcεRI for IgE and are strategically located in different compartments of human lung, where they play a role in several inflammatory disorders and cancer. Immunoglobulin superantigens (e.g., protein A of Staphylococcus aureus and protein L of Peptostreptococcus magnus) bind to the variable regions of either the heavy (V_H3) or light chain (κ) of IgE. IL-33 is a cytokine expressed by epithelial cells that exerts pleiotropic functions in the lung. The present study investigated whether immunoglobulin superantigens protein A and protein L and IL-33 caused the release of inflammatory (histamine), angiogenic (VEGF-A) and lymphangiogenic (VEGF-C) factors from HLMCs. The results show that protein A and protein L induced the rapid (30 min) release of preformed histamine from HLMCs. By contrast, IL-33 did not induce the release of histamine from lung mast cells. Prolonged incubation (12 h) of HLMCs with superantigens and IL-33 induced the release of VEGF-A and VEGF-C. Preincubation with IL-33 potentiated the superantigenic release of histamine, angiogenic and lymphangiogenic factors from HLMCs. Our results suggest that IL-33 might enhance the inflammatory, angiogenic and lymphangiogenic activities of lung mast cells in pulmonary disorders.

Keywords: IL-33; VEGF-A; VEGF-C; allergy; asthma; histamine; mast cell; protein A; protein L; superantigen.

Figure 1

(A) Effects of increasing concentrations of human IgG anti-IgE purified from the serum of an atopic dermatitis patient [85,95] on histamine release and the production of VEGF-A and VEGF-C from four different preparations of human lung mast cells (HLMCs). HLMCs were incubated (45 min at 37 °C) with the indicated concentrations of IgG anti-IgE for histamine secretion or (12 h at 37 °C) for VEGF-A and VEGF-C release. Each bar is the mean ± SEM; (B) Correlation (r = 0.76; p < 0.001) between VEGF-A release and the percent histamine secretion caused by human IgG anti-IgE from HLMCs; (C) Correlation (r = 0.57; p < 0.05) between VEGF-C release and the percent histamine secretion caused by human IgG anti-IgE from HLMCs; (D) Correlation (r = 0.89; p < 0.001) between VEGF-A and VEGF-C release caused by human IgG anti-IgE from HLMCs.

Figure 2

(A) Effects of increasing concentrations of protein A on histamine release and the production of VEGF-A and VEGF-C from four different preparations of human lung mast cells (HLMCs). HLMCs were incubated (45 min at 37 °C) with the indicated concentrations of protein A for histamine secretion or (12 h at 37 °C) for VEGF-A and VEGF-C release. Each bar is the mean ± SEM; (B) Correlation (r = 0.59; p < 0.05) between VEGF-A release and the percent histamine secretion caused by protein A from HLMCs; (C) Correlation (r = 0.82; p < 0.001) between VEGF-C release and the percent histamine secretion caused by protein A from HLMCs; (D) Correlation (r = 0.64; p < 0.01) between VEGF-A and VEGF-C release caused by protein A from HLMCs from HLMCs.

Figure 3

(A) Effects of increasing concentrations of IL-33 on histamine release and the production of VEGF-A and VEGF-C from four different preparations of human lung mast cells (HLMCs). HLMCs were incubated (45 min at 37 °C) with the indicated concentrations of IL-33 for histamine secretion or (12 h at 37 °C) for VEGF-A and VEGF-C release. Each bar is the mean ± SEM; (B) Lack of correlation (r = 0.20; NS) between VEGF-A release and the percent histamine secretion caused by IL-33 from HLMCs; (C) Lack of correlation (r = 0.19; NS) between VEGF-C release and the percent histamine secretion caused by IL-33 from HLMCs; (D) Correlation (r = 0.91; p < 0.001) between VEGF-A and VEGF-C release caused by IL-33 from HLMCs.

Figure 3

(A) Effects of increasing concentrations of IL-33 on histamine release and the production of VEGF-A and VEGF-C from four different preparations of human lung mast cells (HLMCs). HLMCs were incubated (45 min at 37 °C) with the indicated concentrations of IL-33 for histamine secretion or (12 h at 37 °C) for VEGF-A and VEGF-C release. Each bar is the mean ± SEM; (B) Lack of correlation (r = 0.20; NS) between VEGF-A release and the percent histamine secretion caused by IL-33 from HLMCs; (C) Lack of correlation (r = 0.19; NS) between VEGF-C release and the percent histamine secretion caused by IL-33 from HLMCs; (D) Correlation (r = 0.91; p < 0.001) between VEGF-A and VEGF-C release caused by IL-33 from HLMCs.

Figure 4

Effects of short-term priming by IL-33 an protein A-induced release of histamine (A), VEGF-A (B), and VEGF-C (C) from HLMCs. Mast cells were preincubated (30 min at 37 °C) with IL-33 (30 ng/mL) before exposure to protein A (100 nM). After 45 min incubation at 37 °C, HLMCs were harvested, centrifuged, and histamine release measured in the supernatants. For the evaluation of VEGFs, HLMCs were incubated for 12 h at 37 °C. At the end of incubation, cells were harvested, centrifuged and VEGF-A and VEGF-C measured in the supernatants. Results show the mean ± SEM obtained in three experiments. **p < 0.01; *** p < 0.001.

Figure 5

Effects of short-term priming by IL-33 and protein L-induced release of histamine (A), VEGF-A (B), and VEGF-C (C) from HLMCs. Mast cells were preincubated (30 min at 37 °C) with IL-33 (30 ng/ml) before exposure to protein L (100 nM). After 45 min incubation at 37 °C, HLMCs were harvested, centrifuged, and histamine release measured in the supernatants. For the evaluation of VEGFs, HLMCs were incubated for 12 h at 37 °C. At the end of incubation, cells were harvested, centrifuged and VEGF-A and VEGF-C measured in the supernatants. Results show the mean ± SEM of triplicate determinations obtained in a typical experiment. ** p < 0.01; *** p < 0.001.