CONICET | Buscador de Institutos y Recursos Humanos

Purpose: Proteases play an essential role in the pathophysiology of inflammatory boweldisease (IBD), contributing to the intestinal mucosal lesions through the degradation of theextracellular matrix and alteration of the barrier function. Ulcerative colitis (UC) is characterized by an extensive infiltrate of neutrophils into the mucosa and hence, increasedproteolytic activity. Human neutrophil elastase (HNE) is a serine protease that has beenreported to be increased in UC patients? intestinal mucosa. Based on our previous studies, wehypothesized that HNE might induce proteolytic degradation and loss of function of therapeutic monoclonal antibodies in IBD patients.Patients and Methods: Elastase expression and elastinolytic activity were determined inmucosal explants from ulcerative colitis patients (n=6) and cultured ex vivo in the presenceor absence of recombinant elafin. Enzymatic digestions of therapeutic monoclonal antibodieswere performed using recombinant HNE and elafin. The integrity of the therapeutic antibodies was evaluated by immunoblotting and protein G binding assay, whereas their TNFneutralizing activity was assessed with a reporter cell line.Results: We found that HNE and its elastinolytic activity were increased in the gut mucosaof UC patients. We also demonstrated that HNE cleaved biological drugs, impairing theTNF-α neutralizing capacity of anti-TNF monoclonal antibodies. This proteolytic degradation was inhibited by the addition of the specific inhibitor, elafin.Conclusion: Our results suggest that the high level of proteolytic degradation by mucosalneutrophil elastase, along with a potential imbalance with elafin, contributes to the loss offunction of biologic agents, which are currently used in patients with IBD. These findingsmight explain the non-responsiveness of UC patients to therapeutic monoclonal antibodiesand suggest the potential beneficial concomitant use of elafin in this treatment.