Downregulation of epithelial apoptosis and barrier repair in active Crohn’s disease by tumour necrosis factor α antibody treatment
- 1Departments of Gastroenterology, Infectious Diseases, and Rheumatology, Charité Campus Benjamin Franklin, Berlin, Germany
- 2Department of Clinical Physiology, Charité Campus Benjamin Franklin, Berlin, Germany
- Correspondence to:
Professor J D Schulzke
Medizinische Klinik I, Charitè-Universitary Medicine Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, Berlin 12200, Germany;
- Accepted 17 February 2004
- Revised 3 February 2004
Background and aims: Barrier dysfunction is an important feature contributing to inflammation and diarrhoea in Crohn’s disease (CD). Recently, tumour necrosis factor α (TNF-α) antibodies were recognised as effective in steroid refractory CD. The aim of this study was to characterise the effects of this therapy on the epithelial barrier.
Patients and methods: Forceps biopsies were obtained from the sigmoid colon before and 14 days after TNF-α antibody therapy in 11 patients treated for chronic active CD (Crohn’s disease activity index >150). Epithelial apoptoses were measured after terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labelling (TUNEL) and 4′,6-diamidino-2-phenylindole staining. Epithelial resistance was determined by alternating current impedance analysis in miniaturised Ussing chambers. Occludin, claudin 1, and claudin 4 expression was quantified in immunoblots.
Results: The epithelial apoptotic ratio was 2.1 (0.2)% in controls and increased to 5.3 (1.0)% in CD. TNF-α antibody therapy decreased the apoptotic ratio to 2.9 (1.0)% (normalised in 10 of 11 patients). In parallel, epithelial resistance was lower in CD than in controls (24 (3) v 42 (3) Ω×cm2) and improved to 34 (3) Ω×cm2 after therapy. Occludin, claudin 1, and claudin 4 were not affected by TNF-α antibody therapy. In support of a functional role of epithelial apoptoses in CD, a similar decrease in resistance of −40% was observed when the apoptotic rate was selectively upregulated from 2.6% to 5.4% with camptothecin in HT-29/B6 cells.
Conclusions: Epithelial apoptoses were upregulated in the colon in CD and restored to normal in 10 of 11 patients by TNF-α antibody therapy. This is the structural correlate of epithelial barrier dysfunction measured as epithelial resistance while expression of tight junction proteins did not contribute to this therapeutic effect.
- TNF-α, tumour necrosis factor α
- DAPI, 4′,6-diamidino-2-phenylindole
- Re, epithelial electrical wall resistance
- Rsub, subepithelial electrical wall resistance
- Rt, transmural wall resistance
- CD, Crohn’s disease
- TUNEL, terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labelling
- CDAI, Crohn’s disease activity index
↵* S Zeissig and C Bojarski contributed equally to this work.