WNT-5A:signaling and functions in health and disease

WNT-5A plays critical roles in a myriad of processes from embryonic morphogenesis to the maintenance of post-natal homeostasis. WNT-5A knock-out mice fail to survive and present extensive structural malformations. WNT-5A predominantly activates β-catenin-independent WNT signaling cascade but can also activate β-catenin signaling to relay its diverse cellular effects such as cell polarity, migration, proliferation, cell survival, and immunomodulation. Moreover, aberrant WNT-5A signaling is associated with several human pathologies such as cancer, fibrosis, and inflammation. Thus, owing to its diverse functions, WNT-5A is a crucial signaling molecule currently under intense investigation with efforts to not only delineate its signaling mechanisms and functions in physiological and pathological conditions, but also to develop strategies for its therapeutic targeting

Regulation of actin dynamics by WNT-5A:implications for human airway smooth muscle contraction

A defining feature of asthma is airway hyperresponsiveness (AHR), which underlies the exaggerated bronchoconstriction response of asthmatics. The role of the airway smooth muscle (ASM) in AHR has garnered increasing interest over the years, but how asthmatic ASM differs from healthy ASM is still an active topic of debate. WNT-5A is increasingly expressed in asthmatic ASM and has been linked with Th2-high asthma. Due to its link with calcium and cytoskeletal remodelling, we propose that WNT-5A may modulate ASM contractility. We demonstrated that WNT-5A can increase maximum isometric tension in bovine tracheal smooth muscle strips. In addition, we show that WNT-5A is preferentially expressed in contractile human airway myocytes compared to proliferative cells, suggesting an active role in maintaining contractility. Furthermore, WNT-5A treatment drives actin polymerisation, but has no effect on intracellular calcium flux. Next, we demonstrated that WNT-5A directly regulates TGF-β1-induced expression of α-SMA via ROCK-mediated actin polymerization. These findings suggest that WNT-5A modulates fundamental mechanisms that affect ASM contraction and thus may be of relevance for AHR in asthma

LAIR-1 Limits Neutrophilic Airway Inflammation

Neutrophils are crucial to antimicrobial defense, but excessive neutrophilic inflammation induces immune pathology. The mechanisms by which neutrophils are regulated to prevent injury and preserve tissue homeostasis are not completely understood. We recently identified the collagen receptor leukocyte-associated immunoglobulin-like receptor (LAIR)-1 as a functional inhibitory receptor on airway-infiltrated neutrophils in viral bronchiolitis patients. In the current study, we sought to examine the role of LAIR-1 in regulating airway neutrophil responses in vivo. LAIR-1-deficient (Lair1−/−) and wild-type mice were infected with respiratory syncytial virus (RSV) or exposed to cigarette smoke as commonly accepted models of neutrophil-driven lung inflammation. Mice were monitored for cellular airway influx, weight loss, cytokine production, and viral loads. After RSV infection, Lair1−/− mice show enhanced airway inflammation accompanied by increased neutrophil and lymphocyte recruitment to the airways, without effects on viral loads or cytokine production. LAIR-1-Fc administration in wild type mice, which blocks ligand induced LAIR-1 activation, augmented airway inflammation recapitulating the observations in Lair1−/− mice. Likewise, in the smoke-exposure model, LAIR-1 deficiency enhanced neutrophil recruitment to the airways and worsened disease severity. Intranasal CXCL1–mediated neutrophil recruitment to the airways was enhanced in mice lacking LAIR-1, supporting an intrinsic function of LAIR-1 on neutrophils. In conclusion, the immune inhibitory receptor LAIR-1 suppresses neutrophil tissue migration and acts as a negative regulator of neutrophil-driven airway inflammation during lung diseases. Following our recent observations in humans, this study provides crucial in-vivo evidence that LAIR-1 is a promising target for pharmacological intervention in such pathologies

Smooth-muscle-derived WNT5A augments allergen-induced airway remodelling and Th2 type inflammation

Asthma is a heterogeneous disease characterized by chronic inflammation and structural changes in the airways. The airway smooth muscle (ASM) is responsible for airway narrowing and an important source of inflammatory mediators. We and others have previously shown that WNT5A mRNA and protein expression is higher in the ASM of asthmatics compared to healthy controls. Here, we aimed to characterize the functional role of (smooth muscle-derived) WNT5A in asthma. We generated a tet-ON smooth-muscle-specific WNT5A transgenic mouse model, enabling in vivo characterization of smooth-muscle-derived WNT5A in response to ovalbumin. Smooth muscle specific WNT5A overexpression showed a clear trend towards enhanced actin (α-SMA) expression in the ASM in ovalbumin challenged animals, but had no effect on collagen content. WNT5A overexpression in ASM also significantly enhanced the production of the Th2-cytokines IL4 and IL5 in lung tissue after ovalbumin exposure. In line with this, WNT5A increased mucus production, and enhanced eosinophilic infiltration and serum IgE production in ovalbumin-treated animals. In addition, CD4+ T cells of asthma patients and healthy controls were stimulated with WNT5A and changes in gene transcription assessed by RNA-seq. WNT5A promoted expression of 234 genes in human CD4+ T cells, among which the Th2 cytokine IL31 was among the top 5 upregulated genes. IL31 was also upregulated in response to smooth muscle-specific WNT5A overexpression in the mouse. In conclusion, smooth-muscle derived WNT5A augments Th2 type inflammation and remodelling. Our findings imply a pro-inflammatory role for smooth muscle-derived WNT5A in asthma, resulting in increased airway wall inflammation and remodelling

Smooth-muscle-derived WNT5A augments allergen-induced airway remodelling and Th2 type inflammation

Asthma is a heterogeneous disease characterized by chronic inflammation and structural changes in the airways. The airway smooth muscle (ASM) is responsible for airway narrowing and an important source of inflammatory mediators. We and others have previously shown that WNT5A mRNA and protein expression is higher in the ASM of asthmatics compared to healthy controls. Here, we aimed to characterize the functional role of (smooth muscle-derived) WNT5A in asthma. We generated a tet-ON smooth-muscle-specific WNT5A transgenic mouse model, enabling in vivo characterization of smooth-muscle-derived WNT5A in response to ovalbumin. Smooth muscle specific WNT5A overexpression showed a clear trend towards enhanced actin (α-SMA) expression in the ASM in ovalbumin challenged animals, but had no effect on collagen content. WNT5A overexpression in ASM also significantly enhanced the production of the Th2-cytokines IL4 and IL5 in lung tissue after ovalbumin exposure. In line with this, WNT5A increased mucus production, and enhanced eosinophilic infiltration and serum IgE production in ovalbumin-treated animals. In addition, CD4+ T cells of asthma patients and healthy controls were stimulated with WNT5A and changes in gene transcription assessed by RNA-seq. WNT5A promoted expression of 234 genes in human CD4+ T cells, among which the Th2 cytokine IL31 was among the top 5 upregulated genes. IL31 was also upregulated in response to smooth muscle-specific WNT5A overexpression in the mouse. In conclusion, smooth-muscle derived WNT5A augments Th2 type inflammation and remodelling. Our findings imply a pro-inflammatory role for smooth muscle-derived WNT5A in asthma, resulting in increased airway wall inflammation and remodelling

Genome-wide association study of polymorphisms predisposing to bronchiolitis

Bronchiolitis is a major cause of hospitalization among infants. Severe bronchiolitis is associated withlater asthma, suggesting a common genetic predisposition. Genetic background of bronchiolitis is notwell characterized. To identify polymorphisms associated with bronchiolitis, we conducted a genomewideassociation study (GWAS) in which 5,300,000 single nucleotide polymorphisms (SNPs) were testedfor association in a Finnish–Swedish population of 217 children hospitalized for bronchiolitis and 778controls. The most promising SNPs (n = 77) were genotyped in a Dutch replication population of 416cases and 432 controls. Finally, we used a set of 202 Finnish bronchiolitis cases to further investigatecandidate SNPs. We did not detect genome-wide significant associations, but several suggestiveassociation signals (p were nominally associated (p (eQTL) for KCND3, previously shown to be associated with occupational asthma. In the additionalset of Finnish cases, the association for another SNP (rs9591920) within a noncoding RNA locus wasfurther strengthened. Our results provide a first genome-wide examination of the genetics underlyingbronchiolitis. These preliminary findings require further validation in a larger sample size.</p

WNT signaling in airway remodeling in asthma: novel roles for WNT-5A in airway smooth muscle

Astma is een chronische obstructieve longaandoening die miljoenen mensen wereldwijd beïnvloedt. Verschillende genetische factoren en omgevingsfactoren kunnen bijdragen aan de ontwikkeling van astma. Structurele veranderingen die in de luchtwegen optreden, ook wel luchtwegremodeling genoemd, zijn een pathofysiologisch kenmerk van astma, die ertoe kunnen leiden dat de longfunctie afneemt naarmate de ziekte ernstiger wordt. Er is weinig bekend over de factoren en mechanismes die luchtwegremodeling veroorzaken, en er is geen behandeling of interventie mogelijk die deze luchtwegremodeling specifiek aanpakt. Dit proefschrift beschrijft de moleculaire mechanismes die betrokken zijn bij luchtwegremodeling waarbij de specifieke focus ligt op WNT signalering. WNT signalering is betrokken bij de ontwikkeling van organen waaronder de longen, en is tevens geïmpliceerd in verschillende ziektes waaronder kanker en fibrose. We hebben de rol van WNT signalering onderzocht met betrekking tot de regulatie van verschillende aspecten van luchtwegremodeling. In luchtweg-gladde spiercellen van astmapatiënten hebben we een verhoogde WNT-5A expressie aangetoond. Vervolgonderzoek in luchtweg-gladde spiercellen heeft aangetoond dat WNT-5A de expressie van extracellulaire matrix en contractiele eiwitten reguleert, wat duidt op luchtwegremodeling zoals dat ook voorkomt in astmapatiënten. Daarnaast beschrijven we de brede modulatie van WNT signaaltransductiecomponenten in een muismodel voor allergeen-geïnduceerde chronische luchtwegontsteking. Interessant is dat WNT inhibitory factor 1, een WNT signaleringsroute remmer, verlaagd is in de longen van deze allergeen-geprovoceerde muizen. Dit proefschrift beschrijft de moleculaire signaleringsroutes en factoren die betrokken zijn bij Wnt gemedieerde luchtwegremodeling bij astma en biedt verschillende potentiele aangrijpingspunten die gebruikt kunnen worden voor therapeutische interventie