Synthesis of interleukin-1 receptor antagonist by Thy-1+ and Thy-1- murine lung fibroblast subsets.
IL-1 is a key cytokine that promotes pulmonary inflammation and fibrosis, as a result of its ability to stimulate lung fibroblast proliferation and collagen synthesis, two hallmarks of fibrosis. The IL-1 receptor antagonist (IL-1Ra) is an important natural inhibitor of IL-1-mediated functions. In models of pulmonary fibrosis induced by chemotherapeutic agents or noxious particles, administration of IL-1Ra significantly ameliorates lung fibrosis. Lung tissue undergoing an inflammatory response shows elevations in IL-1Ra, although it is not clear which pulmonary cells are responsible for the IL-1Ra synthesis. The purpose of this research was to determine whether Thy-1+ and Thy-1- subsets of mouse lung fibroblasts were capable of synthesizing IL-1Ra. In this report, it is demonstrated for the first time that lung fibroblasts are capable of synthesizing IL-1Ra. Both Thy-1+ and Thy-1- parental lines and clones constitutively express IL-1Ra mRNA. Quantitation of IL-1Ra protein indicates that Thy-1+ and Thy-1- fibroblasts secrete similar levels of secreted but not intracellular IL-1Ra. Thy-1- fibroblasts accumulate higher levels of IL-1Ra intracellularly. Moreover, fibroblast-conditioned supernatants containing IL-1Ra significantly suppress the mitogenic response of a T cell clone, D10G4.1, to concanavalin A and IL-1 beta. Overall, our observations indicate that Thy-1+ and Thy-1- fibroblasts release IL-1Ra and possess an IL-1-specific inhibitory activity in their supernatants. In vivo, fibroblast-derived IL-1Ra may serve to regulate IL-1-mediated effects in an autocrine and/or paracrine fashion to maintain homeostasis in the pulmonary interstitium.
Silvera
M R
MR
University of Rochester Cancer Center, University of Rochester School of Medicine and Dentistry, NY 14642, USA.
Phipps
R P
RP
D000818:Animals; D001483:Base Sequence; D002455:Cell Division / Q000276:immunology; D002460:Cell Line; D005347:Fibroblasts / Q000276:immunology / Q000378:metabolism; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000037:antagonists & inhibitors*; D008168:Lung / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000096:biosynthesis; D017472:Receptors, Interleukin-1 / Q000037:antagonists & inhibitors*; D011994:Recombinant Proteins / Q000096:biosynthesis; D012795:Sialoglycoproteins / Q000096:biosynthesis*; D018800:Thy-1 Antigens
C507764:Il1rn protein, mouse; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D012333:RNA, Messenger; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins; D012795:Sialoglycoproteins; D018800:Thy-1 Antigens