DOP114 LDN-071, the novel amino acid-based PAI-1 inhibitor, significantly reduces the severity of acute and chronic inflammation in colitis models

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Abstract Background Over recent decades, significant progress has been made in the pharmacological management of Inflammatory Bowel Diseases (IBD). However, the sustained efficacy of existing anti-inflammatory therapies remains suboptimal, highlighting the urgent need for novel treatments. Recent studies have implicated the coagulation pathway, particularly Plasminogen Activator Inhibitor 1 (PAI-1), as a crucial link between epithelium and inflammation in IBD. Genetic deletion of PAI-1 has been shown to reduce experimental colitis severity in mice. Based on these findings, we aimed to develop and evaluate novel PAI-1 inhibitors for IBD treatment. Methods Using the A3SMO® platform, we synthesized LDN-071, an amino acid-based PAI-1 inhibitor, and assessed its inhibitory potential and cytotoxicity in vitro. Acute and chronic colitis models were induced in mice using DSS, with 10 mg/bwkg LDN-071 administered orally. Body weight, spleen weight, and colon length were monitored, while colon histology was analysed. Cytokine expression was measured via ELISA and qRT-PCR, and collagen deposition was quantified using a hydroxyproline assay. Human colon organoid (HCO) and fibroblast (FB) cultures from IBD patients were used to evaluate LDN-071’s effects. Toxicity was assessed in vivo in mice. Results LDN-071 effectively inhibited PAI-1 in vitro without cytotoxicity (1µM–1mM). In DSS-treated mice, 10 mg/bwkg LDN-071 prevented body weight loss, bloody diarrhea, colon shortening, and spleen enlargement. Histological analysis showed that PAI-1 inhibition significantly reduced severe inflammation, ulceration, crypt structure loss, and goblet cell depletion in acute and chronic colitis models. Additionally, PAI-1 inhibition reduced mucosal TNF-α, IL-1β, and IL-6 expression during acute inflammation. In chronic colitis, LDN-071 decreased inflammation, epithelial erosion, and fibrosis while significantly lowering collagen deposition. Importantly, no toxicity was observed at 100 mg/bwkg LDN-071 for seven days. In vitro, LDN-071 reduced pro-inflammatory cytokine expression in HCOs from IBD patients and significantly decreased fibrosis-related gene expression in patient-derived FB cultures. Conclusion Our results showed that LDN-071, a novel amino acid-based inhibitor of PAI-1, significantly ameliorated the severity of acute and chronic colitis in mice. However, the LDN-071 reduced the expression of inflammation- and fibrosis-related genes and proteins in vitro human models. We propose that the inhibition of PAI-1 could be a potential novel therapeutic strategy in IBD.