Laminin Stimulates Rapid Epithelial Restitution of Rabbit Duodenal Mucosa in Vitro

Background: This study investigated the effect of the basal lamina constituents fibronectin, collagen IV, and laminin on epithelial restitution of rabbit duodenum in vitro. Methods: Rabbit duodenal mucosal sheets were mounted in Ussing chambers, luminally exposed to 10 mM HCl for 10 min, and incubated with buffer or luminal buffer containing 25-100 μg/ml of collagen IV, fibronectin, laminin, or polyclonal antisera directed against these proteins (diluted 1:50-1:20) for 3 h. Resistance was calculated from potential difference and short-circuit current. Mucosal damage was assessed by morphometry on hematoxylin- and eosin-stained sections. Results: Acid exposure caused a 40% drop in resistance (119 ± 5 versus 71 ± 5 Ohm·cm2 before versus after injury; P < 0.05, n = 6) and mucosal damage of 58 ± 4% (n = 6). Three hours after injury resistance was 102 ± 6, 117 ± 4, and 48 ± 5 Ohm·cm2 in the control, laminin, and anti-laminin groups, respectively. Furthermore, 36 ± 2%, 16 ± 2%, and 64 ± 5% of the mucosa was damaged in the control, laminin, and anti-laminin groups, respectively, 3 h after injury (P < 0.05 versus controls). Laminin promoted epithelial wound closure by stimulation of enterocyte migration, which was inhibited by anti-laminin. Fibronectin, collagen IV, anti-fibronectin, and anti-collagen IV did not impair restitution. Conclusion: Our results show that laminin promotes electrophysiologic restoration and epithelial restitution of rabbit duodenum in vitro. We therefore suggest that laminin plays an important part in the orchestration of epithelial integrity and barrier function.