MURINE FIBROBLASTS SYNTHESIZE AND SECRETE KININOGEN IN RESPONSE TO CYCLIC-AMP, PROSTAGLANDIN E(2) AND TUMOR-NECROSIS-FACTOR

Fibroblasts prepared from the meninges of newborn mice or from mouse e mbryos, as well as fibroblast L929 cells, secreted an immunoreactive m aterial (ir-kininogen) against rabbit anti-mouse low-molecular-weight kininogen antibody in response to dibutyryl cAMP. Western blots using a bradykinin-directed monoclonal, as well as a polyclonal anti-mouse l ow-molecular-weight kininogen antibody, showed that ir-kininogen had a molecular weight of 80000 and that it contained a kinin moiety. N-ter minal amino acid sequence of the ir-kininogen was consistent with that of mouse L-kininogen. The ir-kininogen produced by fibroblasts releas ed a kinin by incubating with trypsin and mouse submandibular gland ka llikrein, and it was identified as bradykinin by means of high-perform ance liquid chromatography, indicating that mouse fibroblasts produce and secrete a kininogen. Forskolin, prostaglandin E(2) and tumor necro sis factor cu stimulated the production of ir-kininogen by meningeal f ibroblasts, whereas neither dibutyryl cAMP nor these agents influenced kininogen production by mouse hepatocytes in primary cultures. These results demonstrated that fibroblasts are a source of kininogen in the mouse, and that it is regulated by the inflammatory mediators, prosta glandin E2 and tumor necrosis factor. Therefore locally produced kinin ogen is implicated in pathogenesis of inflammation.