The JAK Inhibitor Tofacitinib Rescues Intestinal Barrier Defects Caused by Disrupted Epithelial-macrophage Interactions

Abstract

Background and Aims Loss-of-function variants in protein tyrosine phosphatase non-receptor type-2 (PTPN2) promote susceptibility to inflammatory bowel diseases (IBD). PTPN2 regulates Janus-kinase (JAK) and signal transducer and activator of transcription (STAT) signaling, while protecting the intestinal epithelium from inflammation-induced barrier disruption. The pan-JAK inhibitor, tofacitinib, is approved to treat ulcerative colitis but its effects on intestinal epithelial cell–macrophage interactions and on barrier properties are unknown. We aimed to determine if tofacitinib can rescue disrupted epithelial-macrophage interaction and barrier function upon loss of PTPN2. Methods Human Caco-2BBe intestinal epithelial cells (IECs) and THP-1 macrophages expressing control or PTPN2-specific shRNA were co-cultured with tofacitinib or vehicle. Transepithelial electrical resistance and 4 kDa fluorescein-dextran flux were measured to assess barrier function. Ptpn2fl/fl and Ptpn2-LysMCre mice, which lack Ptpn2 in myeloid cells, were treated orally with tofacitinib citrate twice daily to assess the in vivo effect on the intestinal epithelial barrier. Colitis was induced via administration of 1.5% DSS in drinking water. Results Tofacitinib corrected compromised barrier function upon PTPN2 loss in macrophages and/or IECs via normalization of (i) tight junction protein expression, (ii) excessive STAT3 signaling, and (iii) IL-6 and IL-22 secretion. In Ptpn2-LysMCre mice, tofacitinib reduced colonic pro-inflammatory macrophages, corrected underlying permeability, and prevented the increased susceptibility to DSS colitis. Conclusions PTPN2 loss in IECs or macrophages compromises IEC-macrophage interactions and reduces epithelial barrier integrity. Both of these events were corrected by tofacitinib in vitro and in vivo. Tofacitinib may have greater therapeutic efficacy in IBD patients harboring PTPN2 loss-of-function mutations.

JAK-STAT Pathway Regulation of Intestinal Permeability: Pathogenic Roles and Therapeutic Opportunities in Inflammatory Bowel Disease

“…Similar to the claudin proteins, the JAK-STAT signaling pathway is also involved in the regulation of ZO-1. Knockdown of PTPN2 in human Caco-2BBe IECs induced the internalization of ZO-1 and formation of gaps between adjacent IECs [ 8 ]. Loss of Ptpn2 in macrophages of mice caused a reduced and more diffuse staining of ZO-1 in the colonic epithelium, demonstrating a major role of these immune cells in regulating intestinal barrier function [ 8 ].…”

“…Knockdown of PTPN2 in human Caco-2BBe IECs induced the internalization of ZO-1 and formation of gaps between adjacent IECs [ 8 ]. Loss of Ptpn2 in macrophages of mice caused a reduced and more diffuse staining of ZO-1 in the colonic epithelium, demonstrating a major role of these immune cells in regulating intestinal barrier function [ 8 ]. Of interest, these effects were nullified with the addition of tofacitinib [ 8 ].…”

“…Inflammatory bowel diseases are multifactorial disorders that manifest from an abnormal immune response towards luminal contents in the digestive tract in processes driven by genetic and environmental risk factors [ 8 , 9 ]. Currently, over two hundred SNPs have been linked to the pathogenesis of IBD, many of which are involved in regulating intestinal epithelial barrier function [ 8 ]. Disruption of the intestinal epithelial barrier, via increased intestinal permeability, is a feature of many chronic inflammatory disorders including IBD.…”

“…This finding has substantial implications in understanding the pathogenesis of IBD as it provides the most robust evidence of increased intestinal permeability predisposing to subsequent onset of CD. Variants in genes belonging to the Janus kinase (JAK)—signal transducer and activator of transcription (STAT) signaling pathway, as well as members of the protein tyrosine phosphatase (PTP) family that act as negative regulators of JAK-STATs, are associated with increased IBD risk [ 8 , 9 ]. JAK-STAT proteins are responsible for mediating receptor signaling of numerous IBD-associated cytokines involved in regulating intestinal permeability [ 9 ].…”

Identification of a Novel Susceptibility Marker for SARS-CoV-2 Infection in Human Subjects and Risk Mitigation with a Clinically Approved JAK Inhibitor in Human/Mouse Cells

“…Indeed a JAK-inhibitor, baricitinib, is in clinical trial (ACTT-2) to reduce disease severity and hospitalization time in COVID-19 29 . Tofacitinib (Xeljanz ® ) is a pan-JAK inhibitor that preferentially inhibits JAK1 and JAK3, is approved to treat RA and the IBD subtype, ulcerative colitis (UC), and we have shown that tofacitinib corrects the consequences of PTPN2-loss in IECs 30 .…”