Imaging the Alternatively Spliced D Domain of Tenascin C in a Preclinical Model of Inflammatory Bowel Disease.

PURPOSE: To image colon-expressed alternatively spliced D domain of tenascin C in preclinical colitis models using near infrared (NIR)-labeled targeted molecular imaging agents. PROCEDURES: A human IgG1 with nanomolar binding affinity specific to the alternatively spliced D domain of tenascin C was generated. Immunohistochemistry identified disease-specific expression of this extracellular matrix protein in the colon of mice given dextran sulfate sodium in the drinking water. The antibody reagent was labeled with the NIR fluorophore IRDye 800CW via amine chemistry and intravenously dosed to evaluate in vivo targeting specificity. Increasing doses of imaging agent were given to estimate the saturating dose. RESULTS: The NIR-labeled proteins successfully targeted colonic lesions in a murine model of colitis. Co-administration of a molar excess competing unlabeled dose reduced normalized uptake in diseased colon by > 70%. Near infrared ex vivo images of colon resected from diseased animals showed saturation at doses exceeding 1 nmol and was confirmed with additional quantitative ex vivo biodistribution. Cellular-level specificity and protein stability were assessed via microscopy. CONCLUSIONS: Our imaging data suggest the alternatively spliced D domain of tenascin C is a promising target for delivery-based applications in inflammatory bowel diseases.

Fibronectin extra domain A as a drug delivery targeting epitope for rheumatoid arthritis.

OBJECTIVES: To assess the ability of monoclonal antibodies (mAbs) specific for fibronectin extra-domain A (FnEDA) to target diseased tissues of mouse collagen induced arthritis (mCIA) models. To explore the parameters of the targeting exhibited by anti-FnEDA mAbs including timing and location. METHODS: Targeting capabilities of anti-FnEDA mAbs were demonstrated by biodistribution study where i.v. injected antibodies were detected by conjugated near-infrared (NIR) fluorophore, 125I label and immunohistochemistry (IHC) of the injected antibody. Location of FnEDA expression in both mCIA and human RA tissue were mapped by IHC. Quantification of anti-FnEDA mAbs targeted to disease tissue was measured by whole-body autoradiography (WBA). Timing of the targeting was interrogated with fluorescent and confocal microscopy using anti-FnEDA mAbs labeled with different fluorophores and injected at different times. RESULTS: Anti-FnEDA mAbs show specific targeting to diseased paws of mCIA animal. The targeting was focused on inflamed synovium which is consistent with FnEDA expression profile in both mCIA and human RA tissues. Anti-FnEDA mAbs accumulated in diseased tissue at pharmacologically relevant concentrations, the targeting was sustained for up to 14 days and FnEDA was able to support targeting of multiple doses of anti-FnEDA mAbs given 5 days apart. CONCLUSION: FnEDA is specifically upregulated in the inflamed tissues of mCIA. Antibodies specific for FnEDA can be useful as molecular delivery vehicles for disease specific targeting of payloads to inflamed joint tissue.

Fibronectin extra domain A as a drug delivery targeting epitope for rheumatoid arthritis

Abstract Objectives: To assess the ability of monoclonal antibodies (mAbs) specific for fibronectin extra-domain A (FnEDA) to target diseased tissues of mouse collagen induced arthritis (mCIA) models. To explore the parameters of the targeting exhibited by anti-FnEDA mAbs including timing and location. Methods: Targeting capabilities of anti-FnEDA mAbs were demonstrated by biodistribution study where i.v. injected antibodies were detected by conjugated near-infrared (NIR) fluorophore, 125I label and immunohistochemistry (IHC) of the injected antibody. Location of FnEDA expression in both mCIA and human RA tissue were mapped by IHC. Quantification of anti-FnEDA mAbs targeted to disease tissue was measured by whole-body autoradiography (WBA). Timing of the targeting was interrogated with fluorescent and confocal microscopy using anti-FnEDA mAbs labeled with different fluorophores and injected at different times. Results: Anti-FnEDA mAbs show specific targeting to diseased paws of mCIA animal. The targeting was focused on inflamed synovium which is consistent with FnEDA expression profile in both mCIA and human RA tissues. Anti-FnEDA mAbs accumulated in diseased tissue at pharmacologically relevant concentrations, the targeting was sustained for up to 14 days and FnEDA was able to support targeting of multiple doses of anti-FnEDA mAbs given 5 days apart. Conclusion: FnEDA is specifically upregulated in the inflamed tissues of mCIA. Antibodies specific for FnEDA can be useful as molecular delivery vehicles for disease specific targeting of payloads to inflamed joint tissue.