P0007 mAb-based targeting of the eAGR2-Fibrinogen interaction as a promising new therapy in Inflammatory Bowel Disease
Authors: Kantar D , Bachiri K , Villemin C , Collini F , Treton X , Beq S , Coyaud E 
Published: January 2025

Abstract

Background
Historically, Fibrinogen (Fg) is known to be crucial in IBD by aiding fibrin deposition, which leads to scar tissue formation and tissue remodeling. High Fg levels in IBD foster chronic inflammation, activate fibroblasts, stimulate extracellular matrix production, promote fibrosis, and hinder normal mucosal repair. Recently, Anterior Gradient 2 (AGR2), an endoplasmic reticulum chaperone protein that is expressed by mucin-secreting epithelial cells, is secreted (eAGR2) under stress and contributes to a plethora of pathogenic processes (e.g. epithelial integrity disruption, monocyte attraction, fibroblast activation, and oncogenesis). AGR2 overexpression in the colon of IBD patients correlates with disease severity and activity. The present report identifies the eAGR2-Fg physical interaction, which opens new therapeutic avenues in IBD care.

Methods
CoIP-MS was used to identify interactors of eAGR2 in Caco2 supernatant. The binding between AGR2 and interactors was orthogonally validated using ELISA and abrogated by proprietary anti-eAGR2 mAb (TH-009). The efficacy of TH-009 in preventing the development of fibrosis was assessed using a murine chronic DSS model of colitis.

Results
IP-MS identified the three Fg subunits as the most abundant eAGR2 interactors in the Caco-2 supernatant. This interaction decreased fourfold with anti-eAGR2 mAbs. ELISA confirmed the specific binding of Fg to AGR2 (p&lt;0.01), which was abrogated by TH-009 in a dose-dependent manner (p&lt;0.001). In a murine chronic DSS model of colitis, multiple features of inflammation and fibrosis went down significantly when treated with TH-009, and anti-inflammatory molecular signature was promoted. For example, fibrosis was decreased by two-fold in TH-009 treated mice compared to that in the untreated DSS group (p&lt;0.001). Also, collagen deposition and aSMA were decreased by 2.4 and 17-fold, respectively (p&lt;0.001). At the mRNA level, a 2-fold decrease of TGFb, and fibronectin and a 3-fold decrease of ColA1 were observed (p=0,05; p&lt;0.05 and p&lt;0.01).

Conclusion
We identified Fg as a central eAGR2 partner and showed that this interaction was disrupted by the anti-eAGR2 mAb. Our results may suggest that eAGR2 binding to Fg impairs the fibrinogen-fibrin maturation cycle, thus maintaining the deleterious signaling observed in IBD. Considering the TH-009 efficacy in preventing fibrosis in vivo, our results support the therapeutic interest of targeting the eAGR2-Fg complex in IBD and other mucosal inflammatory diseases.

References
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