Chemokine stimulation promotes enterocyte migration through laminin-specific integrins

Abstract

Intestinal homeostasis is regulated in part by the single cell layer of the mucosal epithelium. This physical barrier is a prominent part of the innate immune system and possesses an intrinsic ability to heal damage and limit infection. The restitutive epithelial migration phase of healing requires dynamic integrin adhesion to the extracellular matrix. Previously, we have shown that the homeostatic chemokine CXCL12 utilizes intracellular calcium to increase enterocyte migration on laminin. The aim of these studies was to investigate integrin specificity and, in turn, functional responses elicited by CXCL12 stimulation. Analysis of cellular adhesion and spreading revealed CXCL12 preferentially activated laminin-specific integrins compared with collagen IV-binding integrins. Laminin-specific cell adhesion and spreading elicited by CXCL12 was dependent on intracellular calcium. CXCL12 increased activated β1-integrins on the surface of epithelial cells compared with untreated cells. RT-PCR confirmed expression of the laminin-binding integrins-α3β1, -α6β1, and -α6β4. Interestingly, shRNA-mediated depletion of laminin-specific α3- or α6-integrin subunits revealed differential functions. α3-Integrin knockdown reduced basal as well as inducible restitution. Depletion of α6-integrin specifically abolished CXCL12-stimulated, but not TGF-β1 or basal, migration. Depletion with either shα3-integrin or shα6-integrin prevented CXCL12-evoked cell spreading. Our data indicate that CXCL12 stimulates the inside-out activation of laminin-specific integrins to promote cell migratory functions. Together, our findings support the notion that extracellular mediators within the gastrointestinal mucosa coordinate cell-matrix interactions during epithelial restitution.

RNA-seq analysis of mucosal immune responses reveals signatures of intestinal barrier disruption and pathogen entry following Edwardsiella ictaluri infection in channel catfish, Ictalurus punctatus

“…CXCL2 and CXCL12, with closer conservation with mammalian counterparts [68], were both upregulated. Recent research [69,70] indicates that CXCL12 is critical in healing in damaged intestinal epithelium. The pattern of immune evasion continued even among up-regulated genes with macrophage migration inhibitory factor (MIF) and suppressor of cytokine signaling-1 (SOCS1) both induced following bacterial exposure.…”

Engineering Functional Epithelium for Regenerative Medicine and In Vitro Organ Models: A Review

“…39 B-1 subunit integrins contribute to the migration of epithelial cells on laminin and collagen type IV. 40 However, in large wounds, the cells' ability to migrate may not be sufficient to cover the entire wound area.…”

Genomics of immune response to typhoid and cholera vaccines

“…CXCL12 is a homeostatic or constitutive chemokine. The product of this gene plays a key role in damage-healing by stimulating the activation of laminin-specific integrins [36]. V. cholerae infection produces strong inflammatory manifestations [37].…”