LIGHT controls distinct homeostatic and inflammatory gene expression profiles in esophageal fibroblasts via differential HVEM and LT\u03b2R-mediated mechanisms

Mario C Manresa,Haruka Miki,Loan D Duong,Austin W.T Chiang,Michael Croft,Elaine Pham,Seema S Aceves,Kevin Okamoto,Amanda Wu,Praveen Akuthota,Richard Kurten,Quan M Nhu,Nathan E Lewis

doi:10.1038/s41385-021-00472-w

Abstract

Fibroblasts mediate tissue remodeling in eosinophilic esophagitis (EoE), a chronic allergen-driven inflammatory pathology. Diverse fibroblast subtypes with homeostasis-regulating or inflammatory profiles have been recognized in various tissues, but which mediators induce these alternate differentiation states remain largely unknown. We recently identified that TNFSF14/LIGHT promotes an inflammatory esophageal fibroblast in vitro. Herein we used esophageal biopsies and primary fibroblasts to investigate the role of the LIGHT receptors, herpes virus entry mediator (HVEM) and lymphotoxin-beta receptor (LTβR), and their downstream activated pathways, in EoE. In addition to promoting inflammatory gene expression, LIGHT down-regulated homeostatic factors including WNTs, BMPs and type 3 semaphorins. In vivo, WNT2B+ fibroblasts were decreased while ICAM-1+ and IL-34+ fibroblasts were expanded in EoE, suggesting that a LIGHT-driven gene signature was imprinted in EoE versus normal esophageal fibroblasts. HVEM and LTβR overexpression and deficiency experiments demonstrated that HVEM regulates a limited subset of LIGHT targets, whereas LTβR controls all transcriptional effects. Pharmacologic blockade of the non-canonical NIK/p100/p52-mediated NF-κB pathway potently silenced LIGHT’s transcriptional effects, with a lesser role found for p65 canonical NF-κB. Collectively, our results show that LIGHT promotes differentiation of esophageal fibroblasts toward an inflammatory phenotype and represses homeostatic gene expression via a LTβR-NIK-p52 NF-κB dominant pathway.

Highlights

Fibroblasts are increasingly being recognized as plastic cells that can acquire diverse phenotypes in homeostasis and disease[1,2,3,4].Until recently, these cells were thought mainly to participate in tissue healing and, upon activation during disease states, to acquire a myofibroblast phenotype and deposit excess extracellular matrix (ECM) thereby leading to fibrosis and wound contracture[5,6]
Transcriptome revealed that LIGHT down-regulates multiple mediators of homeostatic functions including WNT factors herpes virus entry mediator (HVEM) and LTβR-dependent mechanisms contribute to (WNT5A, WNT2B), WNT receptors and targets (FZD4 and OLFM2), fibroblast-eosinophil tethering in co-culture bone morphogenetic proteins (BMP6) or type 3 semaphorins In previous studies we showed that eosinophils tether to (SEMA3, Fig. 1a)
We build on this and show that LIGHT is a central regulator of fibroblast function in the esophagus by repressing mediators that are likely to be involved in esophageal epithelial homeostasis

Summary

Introduction

Fibroblasts are increasingly being recognized as plastic cells that can acquire diverse phenotypes in homeostasis and disease[1,2,3,4].Until recently, these cells were thought mainly to participate in tissue healing and, upon activation during disease states, to acquire a myofibroblast phenotype and deposit excess extracellular matrix (ECM) thereby leading to fibrosis and wound contracture[5,6]. Recent single cell studies in Th2 and Th1 diseases such as eczema, inflammatory bowel disease, and rheumatoid arthritis have documented the existence of unique fibroblast subsets with distinct transcriptional profiles that allow them to produce homeostatic or inflammatory factors[1,2,4,7] This is well documented in the intestinal tract, where fibroblast populations localized around colonic crypts produce WNT factors, type 3 semaphorins (SEMA3), or bone morphogenetic proteins (BMPs) to sustain epithelial renewal[8,9]. Multicellular inflammatory modules that are rich in inflammatory fibroblasts can predict resistance to TNF-blocking therapies in Crohn’s disease[2] Considering this cumulative evidence of the critical roles of fibroblasts in homeostasis and inflammation, elucidating the factors that drive fibroblast functional changes may represent a new avenue to identify targets for the treatment of chronic inflammatory diseases leading to tissue fibrosis

Methods

Results

Conclusion