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Fig. 5 | Respiratory Research

Fig. 5

From: Nicotine stimulates collagen type I expression in lung via α7 nicotinic acetylcholine receptors

Fig. 5

Matrices Derived from Nicotine-treated Fibroblasts and Mice Stimulate IL-1β Expression in Monocytic Cells. a Lung fibroblasts (5x104 cells/12 well) were treated with nicotine (50 μg/ml) for 120 h. Fibroblasts were removed by osmotic lysis, the plates were washed thoroughly, and human monocytic U937 cells expressing the human interleukin-1β gene promoter connected to a luciferase reporter gene were overlaid atop the fibroblast-derived matrix. Afterwards, expression of the IL-1β promoter was analyzed by luciferase assay. We found that collagen-containing matrices derived from nicotine-treated fibroblasts stimulated monocytic cells to express the pro-inflammatory cytokine IL-1β. Furthermore, nicotine-treated fibroblast matrix induction of IL-1β was inhibited by anti-α2β1 integrin antibodies. b IL-1β gene transcription was not increased in U937 cells cultured on matrices derived from nicotine-treated α7 nAChR deficient primary lung fibroblast matrix over control. c Fibroblasts pretreated with MG 624, an α7 nAChR antagonist (10 μM), concurrently with nicotine inhibited IL-1β expression without affecting baseline expression. d The nicotine-treated fibroblast matrix IL-1β induction was inhibited by MEK-1 inhibitor PD98059 (50 μM), with PD98059 alone bringing IL-1β expression below baseline. e The lungs of mice exposed to nicotine (100 μg/ml in the drinking water for 8 weeks) were isolated for RNA analysis, which showed an increase in IL-1β gene transcription by RT-PCR. f Lungs from control and nicotine-treated mice were stained by immunohistochemistry for IL-1β. Increased staining was present in mice treated with nicotine. Experiments were repeated at least 3 times. Significance was assessed using p values <0.05 obtained by 2-way ANOVA with Bonferroni posttest

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