Lymphotoxin beta receptor signaling directly controls airway smooth muscle deregulation and asthmatic lung dysfunction

Background: Dysregulation of airway smooth muscle cells (ASM) is central to the severity of asthma. Which molecules dominantly control ASM in asthma is unclear. High levels of the cytokine LIGHT (aka TNFSF14) have been linked to asthma severity and lower baseline predicted FEV1 percentage, implying that signals through its receptors might directly control ASM dysfunction.Objective: Our study sought to determine whether signaling via lymphotoxin beta receptor (LTPR) or herpesvirus entry mediator from LIGHT dominantly drives ASM hyperreactivity induced by allergen.Methods: Conditional knockout mice deficient for LTPR or herpesvirus entry mediator in smooth muscle cells were used to determine their role in ASM deregulation and airway hyperresponsiveness (AHR) in vivo. Human ASM were used to study signals induced by LTPR.Results: LTPR was strongly expressed in ASM from normal and asthmatic subjects compared to several other receptors implicated in smooth muscle deregulation. Correspondingly, conditional deletion of LTPR only in smooth muscle cells in smMHCCreLTPRfl/fl mice minimized changes in their numbers and mass as well as AHR induced by house dust mite allergen in a model of severe asthma. Intratracheal LIGHT administration independently induced ASM hypertrophy and AHR in vivo dependent on direct LTPR signals to ASM. LIGHT promoted contractility, hypertrophy, and hyperplasia of human ASM in vitro. Distinguishing LTPR from the receptors for IL-13, TNF, and IL-17, which have also been implicated in smooth muscle dysregulation, LIGHT promoted NF-kB-inducing kinase-dependent noncanonical nuclear factor kappa-light-chain enhancer of activated B cells in ASM in vitro, leading to sustained accumulation of F-actin, phosphorylation of myosin light chain kinase, and contractile activity.Conclusions: LTPR signals directly and dominantly drive airway smooth muscle hyperresponsiveness relevant for pathogenesis of airway remodeling in severe asthma. (J Allergy Clin Immunol 2023;151:976-90.)

Automated summary

This study found that signaling through lymphotoxin beta receptor and herpesvirus entry mediator from LIGHT directly controls the dysregulation of airway smooth muscle cells in asthma. By using animal models and in vitro experiments, it was discovered that these receptors play a crucial role in airway smooth muscle hyperresponsiveness and remodeling.