WNT and β-catenin signalling in airway smooth muscle: emerging concepts for asthma

Astma is een veelvoorkomende chronische ontstekingsziekte van de luchtwegen die wordt gekenmerkt door terugkerende symptomen, belemmering van de luchtstroom en bronchospasme. De luchtweg-gladde spier draagt in belangrijke mate bij aan deze toegenomen vernauwing, middels samentrekking, toename in massa, of aanmaak van ontstekingsfactoren. Waar het de gladdespier betreft richten de huidige therapien voor astma zich voornamelijk op luchtwegverwijding, maar voor de overige kenmerken, waaronder toegenomen massa, bestaat er nog geen specifieke behandelingsstrategie. In dit proefschrift gaan we in op de rol van zogenaamde WNT groeifactoren bij deze processen. We laten zien dat WNT groeifactoren op vele vlakken kunnen bijdragen aan de pathofysiologie van astma. Dit hebben we aangetoond met luchtweggladdespiercellen die we in kweek hebben gebracht, maar ook met transgene muizen die WNT groeifactoren overproduceren in de spier. Uit deze modellen hebben we geleerd dat de factor WNT-5A, die in de spier bij astma verhoogd aanwezig is, contractiliteit van de spier bevordert, en tevens wordt uitgescheiden door de cel, waar het ontstekingsbevorderende interactie kan aangaan met naburige ontstekingscellen. Ook blijken WNT groeifactoren betrokken bij spierverdikking. In allergeen-behandelde muizen kon spierverdikking worden voorkomen door deze signaaltransductieroute farmacologisch te remmen. Dit onderzoek toont aan dat WNT groeifactoren, in het bijzonder WNT-5A, bijdragen aan de chronische pathologie van allergisch astma. Farmacologische inhibitie van WNT groeifactoren kan zowel luchtwegverwijdend als ontstekingsremmend werken en tevens de spiermassa terugdringen. Zo creëert het onderzoek nieuwe inzichten in mogelijke toekomstige therapieën gericht op de chronische component van astma, waaronder spierverdikking, waarvoor tot op heden nog geen farmacologische behandeling bestaat

β-Catenin Directs Nuclear Factor-κB p65 Output via CREB-Binding Protein/p300 in Human Airway Smooth Muscle

β-Catenin is a multifunctional protein that apart from its role in proliferative and differentiation events, also acts upon inflammatory processes, mainly via interaction with nuclear factor-κB (NF-κB). However, there is still controversy as to whether β-catenin facilitates or represses NF-κB output. Insights into the molecular mechanisms underlying the interaction between β-catenin and NF-κB have highlighted the cofactors CREB-binding protein (CBP) and p300 as important candidates. Here, we hypothesized that the interaction of β-catenin with CBP/p300 directs NF-κB output. Using human airway smooth muscle (ASM) cells, we found that β-catenin is essential in interleukin -1β (IL-1β)-mediated expression of interleukin-6 (IL-6) by promoting nuclear translocation of the p65 subunit of NF-κB. These effects were independent from WNT pathway activation or other factors that promote β-catenin signaling. In the nucleus, inhibition of either the CBP- or p300-β-catenin interaction could regulate NF-κB output, by enhancing (CBP inhibition) or inhibiting (p300 inhibition) IL-1β-induced expression of IL-6, respectively. Acetylation of p65 by p300 likely underlies these events, as inhibition of the p300-β-catenin interaction diminished levels of acetylated p65 at lysine 310, thereby reducing p65 transcriptional activity. In conclusion, β-catenin is a critical component of NF-κB-mediated inflammation in human ASM, affecting transcriptional output by interacting with the nuclear cofactors CBP and p300. Targeting β-catenin may be an alternative strategy to treat airway inflammation in patients with airway disease, such as asthma

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

The Einstein Cross: constraint on dark matter from stellar dynamics and gravitational lensing

[Abridged] We present two-dimensional line-of-sight stellar kinematics of the lens galaxy in the Einstein Cross, obtained with the GEMINI 8m telescope, using the GMOS integral-field spectrograph. The velocity map shows regular rotation up to ~100 km/s around the minor axis of the bulge, consistent with axisymmetry. The velocity dispersion map shows a weak gradient increasing towards a central (R<1") value of sigma_0=170+/-9 km/s. We deproject the observed surface brightness from HST imaging to obtain a realistic luminosity density of the lens galaxy, which in turn is used to build axisymmetric dynamical models that fit the observed kinematic maps. We also construct a gravitational lens model that accurately fits the positions and relative fluxes of the four quasar images. We find that the resulting luminous and total mass distribution are nearly identical around the Einstein radius R_E = 0.89", with a slope that is close to isothermal, but which becomes shallower towards the center if indeed mass follows light. The dynamical model fits to the observed kinematic maps result in a total mass-to-light ratio (M/L)_dyn=3.7+/-0.5 M_sun/L_sun,I (in the I-band). This is consistent with the Einstein mass M_E = 1.54 x 10^10 M_sun divided by the (projected) luminosity within R_E, which yields a total mass-to-light ratio of (M/L)_E=3.4 M_sun/L_sun,I, with an error of at most a few per cent. We estimate from stellar populations model fits to colors of the lens galaxy a stellar mass-to-light ratio (M/L)_* from 2.8 to 4.1 M_sun/L_sun,I. Although a constant dark matter fraction of 20 per cent is not excluded, dark matter may play no significant role in the bulge of this ~L* early-type spiral galaxy.Comment: 18 pages, 8 figures, published in ApJ, 2010, 719, 148

Patient-reported physical functioning is limited in almost half of critical illness survivors 1-year after ICU-admission:A retrospective single-centre study

Post-intensive care unit (ICU) sequelae, including physical and mental health problems, are relatively unexplored. Characteristics commonly used to predict outcome lack prognostic value when it comes to long-term physical recovery. Therefore, the objective of this study was to assess the incidence of non-recovery in long-stay ICU-patients. In this single-centre study, retrospective data of adults with an ICU stay >48 hours who visited the specialized post-ICU clinic, and completed the Dutch RAND 36-item Short Form questionnaire at 3 and 12 months post-ICU, were retrieved from electronic patient records. In cases where physical functioning scores at 12 months were below reference values, patients were allocated to the physical non-recovery (NR) group. Significantly different baseline and (post-)ICU-characteristics were assessed for correlations with physical recovery at 12 months post-ICU. Of 250 patients, 110 (44%) fulfilled the criteria for the NR-group. Neither the severity of illness, type of admission, nor presence of sepsis did not differ between groups. However, NR-patients had a higher age, were more often female, and had a higher incidence of co-morbidities. Shorter LOS ICU, lower incidence of medical comorbidities, and better physical performance at 3 months were significantly correlated with 1-year physical recovery. Comorbidities and reduced physical functioning at 3 months were identified as independent risk-factors for long-term physical non-recovery. In conclusion, a substantial proportion of long-stay ICU-patients who visited the standard care post-ICU clinic did not fulfil the criteria for full physical recovery at 12 months post-ICU. Commonly used ICU-characteristics, such as severity of illness, do not have sufficient prognostic value when it comes to long-term recovery of health-related quality of life

Beam-induced Fe nanopillars as tunable domain-wall pinning sites

Focused-electron-beam-induced deposition (FEBID) is employed to create freestanding magnetic nanostructures. By growing Fe nanopillars on top of a perpendicular magnetic domain wall (DW) conduit, pinning of the DWs is observed due to the stray fields emanating from the nanopillar. Furthermore, a different DW pinning behavior is observed between the up and down magnetic states of the pillar, allowing to deduce the switching fields of the pillar in a novel way. The implications of these results are two-fold: not only can 3-dimensional nano-objects be used to control DW motion in applications, it is also proposed that DW motion is a unique tool to probe the magnetic properties of nano-objects

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