Abstract 34: Methotrexate Inhibits Vein Wall Scarring in Experimental Deep Vein Thrombosis: Implications for the Post-Thrombotic Syndrome

Abstract

Background: Despite anticoagulant therapy, the post-thrombotic syndrome (PTS) remains a frequent, morbid complication of deep venous thrombosis (DVT). There are no effective clinical approaches beyond anticoagulation to prevent and mitigate PTS, which is driven by inflammation, impaired thrombus resolution, and vein wall scarring leading to valvular reflux. Methotrexate (MTX) is a FDA-approved antimetabolite drug that exerts multiple anti-inflammatory actions. Here we investigate the effects of MTX on vein wall scarring, a key mediator of PTS, in experimental murine DVT. Methods: Stasis VT was established by inferior vena cava complete ligation in C57Bl6 mice (n=60) on day 0. MTX (0.7 mg/kg) or PBS was intraperitoneal injected daily from day 1 to sacrifice. Thrombus burden, vein wall scarring, inflammatory gene expression and macrophage content were assessed at multiple timepoints. Results: MTX decreased Carstairs’ and picrosirius red-assessed vein wall thickness by 36.52% on day 8 (n=6 for each group, p<0.05 vs PBS). Macrophage recruitment in the vein wall was inhibited by MTX at day 8 (p<0.05 vs. PBS). MTX further inhibited vein wall mRNA expression of inflammatory markers CD68 and cathepsin B (p<0.05 vs. PBS). At day 4, neutrophil infiltration in the vein wall was similar in both groups (p>0.05). Thrombus burden, weight, length and mass were similar for both groups on both day 4 (p>0.05) and day 8 (p>0.05). Conclusions: MTX attenuates vein wall scarring in association with the macrophage-mediated inflammatory response in VT, without impairing thrombus resolution. MTX administration following DVT may offer a new translatable approach to reduce the post-thrombotic syndrome.