Inhibition of plasminogen activator inhibitor-1 attenuates against intestinal fibrosis in mice

Background/Aims@#Intestinal fibrosis is a major complication of Crohn’s disease (CD). The profibrotic protein transforming growth factor-β (TGF-β) has been considered to be critical for the induction of the fibrotic program. TGF-β has the ability to induce not only the expression of extracellular matrix (ECM) including collagen, but also the production of plasminogen activator inhibitor-1 (PAI-1) that prevents enzymatic degradation of the ECM during the onset of fibrotic diseases. However, the significance of PAI-1 in the developing intestinal fibrosis has not been fully understood. In the present study, we examined the actual expression of PAI-1 in fibrotic legion of intestinal inflammation and its correlation with the abnormal ECM deposition. @*Methods@#Chronic intestinal inflammation was induced in BALB/c mice using 8 repeated intrarectal injections of 2,4,6-trinitrobenzene sulfonic acid (TNBS). TM5275, a PAI-1 inhibitor, was orally administered as a carboxymethyl cellulose suspension each day for 2 weeks after the sixth TNBS injection. @*Results@#Using a publicly available dataset (accession number, GSE75214) and TNBS-treated mice, we observed increases in PAI-1 transcripts at active fibrotic lesions in both patients with CD and mice with chronic intestinal inflammation. Oral administration of TM5275 immediately after the onset of intestinal fibrosis upregulated MMP-9 (matrix metalloproteinase 9) and decreased collagen accumulation, resulting in attenuation of the fibrogenesis in TNBS-treated mice. @*Conclusions@#PAI-1-mediated fibrinolytic system facilitates collagen degradation suppression. Hence, PAI-1 inhibitor could be applied as an anti-fibrotic drug in CD treatment.

[Loss of heterozygosity induced by cyclophosphamide at tk locus in human lymphoblastoid cell line TK6].

OBJECTIVE: Human lymphoblastoid cell line TK6 was used to investigate TK gene mutation frequency and the loss of heterozygosity (LOH) induced by cyclophosphamide (CP). METHODS: Relative survival, mutation frequency at tk locus induced by CP (+S9) after 4 h treatment were detected. DNA isolated from mutants in the control culture and CP treatment group was analyzed for LOH. RESULTS: Exposure to CP for 4 h decreased relative survival, induced TK gene mutation in a dose-dependent manner. Doubling time of normally and slowly growing mutants was (14.6 +/- 1.74) h and (35.8 +/- 3.78) h respectively. The percentage of hemizygous LOH in CP-induced mutants (50%) was 2.4 times than that of the control (20.7%). CONCLUSION: Great damage to TK gene is the main cause of mutation induced by CPin TK6 cells.