Fig 2: TGFß signaling controls type XVIII collagen gene expression. A single dose of CCl4 was administered and mice were sacrificed at 0, 48, 96, 144 and 192 hour time points. (A–E) DAB stain indicates Smad2 localization during the injury response. Hem, hematoxylin. (F) Gene expression levels for long- and short-chain Col18a1 in mice treated with recombinant TGFß1 as determined by quantitative real-time PCR. Three independent experiments were performed for this analysis. (G,H) AML12 cells treated with 5 ng/ml recombinant TGFß1 and stained for type XVIII collagen with TOPRO3 counterstain. *P<0.05, ****P<0.001.

Fig 3: Type XVIII collagen plays a crucial role in the response of liver to acute injury. (A) Wild-type (n=6) and Col18a1-/- (n=14) mice were subjected to a 24-day CCl4 challenge. Recombinant endostatin (ES) was administered to an additional Col18a1-/- cohort (n=6) treated with CCl4. The Kaplan-Meier curve shows that Col18a1-/- mice had a severe acute response to the hepatotoxin and were moribund within the first few days of treatment. Endostatin administration did not improve survival in these mice. (B–E) Masson’s trichrome staining of (B,C) wild-type and (D,E) Col18a1-/- mice after CCl4 induction reveals extensive damage within the centrilobular zone of Col18a1-/- mice, including lipid accumulation (arrows) and ballooning degeneration (arrowheads). Less-extensive damage was observed in wild-type mice. (F) TUNEL staining after 48 hours in sham- and CCl4-treated wild-type and Col18a1-/- mice reveals an increase in cell death in the Col18a1-/- (n=4) mice as represented in the bar graph. (G) Centrilobular proliferation was observed in wild-type mice 48 hours after CCl4 injections, whereas Col18a1-/- mice displayed a mild proliferative response (n=4) at the same time point, as represented in the bar graph. *P<0.05.

Fig 4: Altered matrix deposition in Col18a1-/- mice with acute liver injury. (A-D) 48 hours after a single dose of CCl4, fibrin deposition within the damaged centrilobular zone of Col18a1-/- mice was patchy compared with wild type (WT) and (E) decreased significantly as determined by immunohistochemistry. (F–H) a, ß and ? fibrinogen chain mRNA levels as determined by quantitative real-time PCR did not reveal significant changes in gene expression in 48-hour CCl4-treated WT and Col18a1-/- mice (n=4). *P<0.05, ****P<0.001.