Targeting the human βc Receptor inhibits contact dermatitis in a transgenic mouse model

Allergic contact dermatitis (ACD) is a prevalent and poorly controlled inflammatory disease caused by skin infiltration of T cells and granulocytes. The beta common (bc) cytokines GM-CSF, IL-3, and IL-5 are powerful regulators of granulocyte function that signal through their common receptor subunit bc, a property that has made bc an attractive target to simultaneously inhibit these cytokines. However, the species specificity of bc has precluded testing of inhibitors of human bc in mouse models. To overcome this problem, we developed a human bc receptor transgenic mouse strain with a hematopoietic cell‒specific expression of human bc instead of mouse bc. Human bc receptor transgenic cells responded to mouse GM-CSF and IL-5 but not to IL-3 in vitro and developed tissue pathology and cellular inflammation comparable with those in wild-type mice in a model of ACD. Similarly, Il3e/e mice developed ACD pathology comparable with that of wild-type mice. Importantly, the blocking antiehuman bc antibody CSL311 strongly suppressed ear pinna thickening and histopathological changes typical of ACD and reduced accumulation of neutrophils, mast cells, and eosinophils in the skin. These results show that GM-CSF and IL-5 but not IL-3 are major mediators of ACD and define the human bc receptor transgenic mouse as a unique platform to test the inhibitors of bc in vivo.Kwok Ho Yip ... Barbara J. McClure ... Angel F. Lopez ... Harshita Pant ... Hayley S. Ramshaw ... et. a

γδ intraepithelial lymphocytes facilitate pathological epithelial cell shedding via CD103-mediated granzyme release

Background & Aims: Excessive shedding of apoptotic enterocytes into the intestinal lumen is observed in inflammatory bowel disease and is correlated with disease relapse. Based on their cytolytic capacity and surveillance behavior, we investigated whether intraepithelial lymphocytes expressing the γδ T cell receptor (γδ IELs) are actively involved in the shedding of enterocytes into the lumen. Methods: Intravital microscopy was performed on GFP γδ T cell reporter mice treated with intraperitoneal lipopolysaccharide (10 mg/kg) for 90 minutes to induce tumor necrosis factor–mediated apoptosis. Cell shedding in various knockout or transgenic mice in the presence or absence of blocking antibody was quantified by immunostaining for ZO-1 funnels and cleaved caspase-3 (CC3). Granzyme A and granzyme B release from ex vivo–stimulated γδ IELs was quantified by enzyme-linked immunosorbent assay. Immunostaining for γδ T cell receptor and CC3 was performed on duodenal and ileal biopsies from controls and patients with Crohn's disease. Results: Intravital microscopy of lipopolysaccharide-treated mice revealed that γδ IELs make extended contact with shedding enterocytes. These prolonged interactions require CD103 engagement by E-cadherin, and CD103 knockout or blockade significantly reduced lipopolysaccharide-induced shedding. Furthermore, we found that granzymes A and B, but not perforin, are required for cell shedding. These extracellular granzymes are released by γδ IELs both constitutively and after CD103/E-cadherin ligation. Moreover, we found that the frequency of γδ IEL localization to CC3-positive enterocytes is increased in Crohn's disease biopsies compared with healthy controls. Conclusions: Our results uncover a previously unrecognized role for γδ IELs in facilitating tumor necrosis factor–mediated shedding of apoptotic enterocytes via CD103-mediated extracellular granzyme release