Plasma concentrations of PCPE-1 reflect the progression of liver fibrosis in CCl₄-treated mice.

<p>C57/BL/6 mice were given CCl₄ for 6 weeks and then remained untreated for 7 additional weeks. Liver fibrosis was assessed at the indicated times by Sirius red staining, immunoblotting, and immunofluorescence analyses. Plasma concentrations of PCPE-1 were determined by the sandwich ELISA at the indicated time points. <b>(A</b>) Sirius Red staining of liver sections from mice euthanized at weeks 6, 10 and 13. Each panel shows results for a single randomly selected mouse from the indicated group. <b>Red</b>, collagen; <b>Green</b>, non-collagenous proteins. <b>(B</b>)Immunofluorescence for type I collagen and PCPE-1 in liver sections from CCl₄-treated and control mice at different times (given in brackets as the number of weeks). Each panel displays results for a single randomly selected mouse from the indicated group. Collagen type I (red) and PCPE-1 (green) were detected using Rhodamine- and Cy2-conjugated secondary antibodies at 488 and 580 nm, respectively. <b>(C)</b> Plasma concentrations of PCPE-1 after 6 weeks of CCl₄ administration are significantly higher than those of control mice (n = 12). <b>(D</b>) Plasma concentrations of PCPE-1 in CCl₄-treated (▲) and control (●) mice as a function of time. <b>Arrow,</b> termination of CCl₄ treatment. Results are presented as mean ± SD. (n at weeks 0 to 6 = 12; n at weeks 7–10 = 9; n at week 13 = 6). <b>(E)</b> Immunoblot evaluating collagen I and PCPE-1 content in liver extracts from CCl₄-treated and control mice at weeks 6, 10 and 13. Samples from a single control mouse and two CCl₄-treated mice (all randomly selected) were analyzed. The amounts of protein applied on each lane were 4 and 36 μg for collagen and PCPE-1 detection, respectively.