Mast cells induce activation of human lung fibroblasts in vitro

Mast cells core able to induce proliferation of skin fibroblasts; however, their affect on lung fibroblasts has not been clearly established. Using in vitro cocultures of rat or human mast cells with lung fibroblasts, the authors determined whether mast cells alley proliferation, collagen synthesis, and metalloproteinase production, from lung fibroblasts. Mast cells enhanced the proliferation of human fibroblasts (mean +/- SEM: 90% +/- 4.7% increase, P <.001) while inhibiting fibroblast collagen synthesis (48.1% +/- 4.2% decrease, P <.001). Histamine, but not tryptase; significantly enhanced fibroblast proliferation: 92% +/- 5.8 % (P <.001) and 39.2% +/- 4.3% (P> 0.05), respectively. Rat mast cell sonicate added to lung fibroblasts induced the activation of metalloproteinase-9 while inhibiting that of metaloproteinase-2. The addition, of lipopolysaccharide (LPS)-stimulated lung macrophage supernatant further enhanced the proliferative affect of mast cells on fibroblasts (by 60 % +/- 7.8%, P <.001) and induced synthesis of collagen from these cells (190 % 28 % increase versus control, P <.05). This study demonstrates that mast cells influence several aspects of lung fibroblast function in vitro.