The differentiation of interstitial lung fibroblasts into contractile myofibroblasts that proliferate and secrete excessive extracellular matrix is crucial for the pathogenesis of pulmonary fibrosis. performed using GraphPad Prism software (v.7). values 0.05 were considered significant. Results IL-1 Pre- or Cotreatment Inhibits TGF-Cinduced Myofibroblast Differentiation and ECM Production We recently reported that primary HLFs activated with IL-1 produce elevated levels of PGE2, as well as several metabolites of PGD2 that are ligands for the antiinflammatory and antifibrotic transcription factor PPAR (6). Based on this finding, we wanted to determine whether these PGs were functional and could inhibit TGF-Cinduced fibroblast-to-myofibroblast differentiation. We treated primary HLFs with IL-1 either 24 hours before treatment or as a cotreatment with TGF-. IL-1 inhibited both myofibroblast differentiation (Figures 1A and 1B) and ECM production (Figures 1C and 1D), regardless of whether it was used as a pretreatment or cotreatment with TGF-. Although some markers trended toward greater inhibition when IL-1 was used as a pretreatment rather than as a cotreatment, there were no significant differences in protein expression of -SMA, calponin, collagen, or fibronectin between the two treatment regimens. LY317615 (Enzastaurin) Open in a separate window Figure 1. IL-1 pre- or LY317615 (Enzastaurin) cotreatment inhibits TGF-Cinduced myofibroblast differentiation and extracellular matrix production. Primary HLFs were treated with TGF- LY317615 (Enzastaurin) (0.5 ng/ml) alone, or 24 hours after pretreatment with IL-1 (1 ng/ml), or with IL-1 (1 ng/ml) as a cotreatment. (= 3 replicates per condition, protein expression relative to loading control, normalized to TGF-1 alone. ** 0.01 and *** 0.001 by ANOVA, compared with untreated control. # 0.05, ## 0.01, and ### 0.001 by ANOVA, compared with TGF- alone. Results shown are from strain 1; two other fibroblast strains were similar, data not shown. See Figure E1 for details on figure assembly. -SMA = ?smooth muscle actin; Co = cotreatment; HLFs = human lung fibroblasts; Pre = pretreatment; TGF- = transforming growth factor-. Conditioned Medium of IL-1Ctreated HLFs Inhibits TGF-Cinduced Myofibroblast Differentiation Given that IL-1Cactivated HLFs produce high levels of E-, D-, and J-series PGs and their metabolites (6), at least some of which are reported to be antifibrotic, we tested whether conditioned media of IL-1Cactivated HLFs would inhibit TGF-Cinduced myofibroblast differentiation of naive HLFs. Three strains of primary HLFs were treated as illustrated in Figure 2A. Donor HLFs were treated with IL-1 (1 ng/ml) for 24 hours, and LY317615 (Enzastaurin) conditioned media were then removed and used as a cotreatment with TGF- on recipient or target HLFs of the same strain. Myofibroblast differentiation was assessed 72 hours after TGF- treatment by Western blot (Figure 2B) and immunofluorescence (Figure 2C) for -SMA expression. The conditioned media of IL-1Ctreated, but not untreated, HLFs robustly inhibited TGF-Cinduced expression of -SMA. Open in a separate window Figure 2. Conditioned medium of IL-1Ctreated HLFs inhibits TGF-Cinduced myofibroblast differentiation. Donor HLFs were untreated or treated for 24 hours with IL-1 (1 ng/ml) to generate conditioned media. (and = 3 replicates per condition, protein expression relative to loading control, normalized to TGF- with no IL-1 pretreatment. ** 0.01 and *** 0.001 by ANOVA, compared with untreated control. ## 0.01 and ### 0.001 by ANOVA, compared with TGF- with no IL-1 pretreatment. Data from HLF strain 4 are shown; strains 1 and 2 were TGFB1 similar. See Figures E3 and E2 for details on figure assembly. When either fifty percent from the coculture (we.e., inhabitants A or B) was pretreated with IL-1 prior to the coculture was founded, total TGF-Cinduced -SMA, calponin, collagen 1A, and fibronectin proteins levels had been significantly reduced weighed against cocultures where neither source inhabitants was pretreated with IL-1 (Numbers 3BC3E). To your knowledge, this is actually the 1st demonstration that triggered HLFs create practical antifibrotic mediators that work inside a paracrine style to inhibit myofibroblast differentiation by naive fibroblasts. Oddly enough,.