Activation of activin receptor-like kinases curbs mucosal inflammation and proliferation in chronic rhinosinusitis with nasal polyps

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a widespread disease causing obstruction of the nasal cavity. Its cause remains unclear. The transforming growth-factor beta (TGF-beta) superfamily and their receptors, termed Activin receptor-like kinases (ALKs), have recently been suggested to play a role in local airway inflammation, but have so far not been evaluated in human nasal epithelial cells (HNECs) from CRSwNP patients. We demonstrated that ALK1-7 were expressed in the nasal polyp epithelium, and the expression of ALK1-6 was markedly elevated in polyps compared to nasal mucosa from healthy controls. Stimulation with the ALK ligand TGF-beta 1 decreased Ki67 expression in HNECs from CRSwNP patients, not evident in controls. Likewise, TGF-beta 1, Activin A and Activin B, all ALK ligands, decreased IL-8 release and Activin A and Activin B reduced ICAM1 expression on HNECs from CRSwNP patients, not seen in controls. Pre-stimulation with TGF-beta 1, Activin A, BMP4 and Activin B attenuated a TNF-ainduced ICAM1 upregulation on HNECs of CRSwNP. No effect was evident in controls. In conclusion, an increased expression of ALK1-6 was found on polyp epithelial cells and ligand stimulation appeared to reduce proliferation and local inflammation in polyps

Intranasal Administration of poly(I:C) and LPS in BALB/c Mice Induces Airway Hyperresponsiveness and Inflammation via Different Pathways

BACKGROUND: Bacterial and viral infections are known to promote airway hyperresponsiveness (AHR) in asthmatic patients. The mechanism behind this reaction is poorly understood, but pattern recognizing Toll-like receptors (TLRs) have recently been suggested to play a role. MATERIALS AND METHODS: To explore the relation between infection-induced airway inflammation and the development of AHR, poly(I:C) activating TLR3 and LPS triggering TLR4, were chosen to represent viral and bacterial induced interactions, respectively. Female BALB/c or MyD88-deficient C57BL/6 mice were treated intranasally with either poly(I:C), LPS or PBS (vehicle for the control group), once a day, during 4 consecutive days. RESULTS: When methacholine challenge was performed on day 5, BALB/c mice responded with an increase in airway resistance. The maximal resistance was higher in the poly(I:C) and LPS treated groups than among the controls, indicating development of AHR in response to repeated TLR activation. The proportion of lymphocytes in broncheoalveolar lavage fluid (BALF) increased after poly(I:C) treatment whereas LPS enhanced the amount of neutrophils. A similar cellular pattern was seen in lung tissue. Analysis of 21 inflammatory mediators in BALF revealed that the TLR response was receptor-specific. MyD88-deficient C57BL/6 mice responded to poly (I:C) with an influx of lymphocytes, whereas LPS caused no inflammation. CONCLUSION: In vivo activation of TLR3 and TLR4 in BALB/c mice both caused AHR in conjunction with a local inflammatory reaction. The AHR appeared to be identical regardless of which TLR that was activated, whereas the inflammation exhibited a receptor specific profile in terms of both recruited cells and inflammatory mediators. The inflammatory response caused by LPS appeared to be dependent on MyD88 pathway. Altogether the presented data indicate that the development of AHR and the induction of local inflammation might be the result of two parallel events, rather than one leading to another

Endogenous and exogenous glucocorticoid effects in a model of allergic airway inflammation.

Allergic asthma and rhinitis are inflammatory diseases of the airways. Allergic asthma is characterized by eosinophilic inflammation, reversible bronchoconstriction and airway hyperresponsiveness, whereas patients with rhinitis suffer from nasal inflammation, leading to rhinorrhea and nasal congestion. Glucocorticoids (GCs) are one of the major drugs for asthma and rhinitis treatment and can regulate leukocyte trafficking and mediator release. The hypothalamus pituitary-adrenal (HPA) axis regulates the secretion of endogenous GCs, and is one of the major stress effector systems in the body. The main role for the HPA-axis is to facilitate the maintenance of neuroendocrine homeostasis, both at basal and pathological conditions. An understanding of the regulation and function of the HPA axis is important for the evaluation of pathological changes and possible side effects caused by GCs. In the studies presented in this thesis we have used a mouse model to investigate the effects of endogenous GC synthesis and GC receptor inhibition, as well as acute stress, and different doses of exogenous administered GCs on inflammatory cells in different cellular compartments in allergic airway inflammation. We also investigated the effects of acute stress on the neurotrophic mediator, nerve growth factor (NGF) in the airways, during allergic inflammation. In the first study (I), we investigated the effects of endogenous GCs on eosinophilic airway inflammation. Inhibition of GC release with metyrapone (ME) induced an increase of bone marrow eosinophilia and when the ME treatment was combined with a GC receptor antagonist (RU 486) the allergen-induced bone marrow eosinophilia was further enhanced. ME treatment also induced an increase of CD4+ T lymphocytes in the nasal mucosa, both when employed as a single treatment and in combination with RU 486. In the second study (II), timing and dose-dependent effects of dexamethasone (DEX) on eosinophilic airway inflammation were studied. This study provided evidence that a low dose of DEX (1 µg/kg) evoked a stronger inhibitory effect on the eosinophilic airway inflammation, as compared to the effect of the 500 times higher pharmacological dose (500µg/kg) if given before the allergen challenge. When administered simultaneously the allergen challenge, the two doses displayed similar effects. The third study (III), was focused on the effects of timing of a short acute stress on allergic airway inflammation in upper and lower airways. Short stress applied before an allergen challenge decreased the allergen-induced eosinophilia in bronchoalveolar lavage fluid and lungs and also the inflammation in the nasal tissue. No effects on eosinophilia or inflammation were seen when stress was applied after allergen challenge or as a double stress both before and after challenge. The protective effects, seen in the mice stressed prior to the allergen challenge, were GC-dependent. In the fourth study (IV), the aim was to assess how acute stress modulated NGF levels and eosinophils in the airways during non-allergic and mild allergic conditions. We found that short stress increased the levels of NGF locally in the airways in both allergic and non-allergic mice. We also demonstrated that airway eosinophils decreased when stress was applied after allergen-challenge in a model of mild airway inflammation. The stress-evoked increase in NGF and decrease in eosinophilia in the airways were dependent on endogenous GC-synthesis, as evident from pre-treatment with ME. In summary, these results indicate that endogenous GCs may have a protective effect in both upper and lower eosinophilic airway inflammation. Our studies also demonstrate that the inhibitory effect of GCs on the allergic inflammation is timing-dependent. By the use of a GC synthesis inhibitor, we show that the inhibitory effects on the eosinophilic airway inflammation during acute stress are GC-dependent. Acute stress increased local airway NGF and this effect is mediated by endogenous GC synthesis. Thus, we also conclude that NGF may function as a mediator in the psychoneuroimmunological stress-response

Deprived TLR9 expression in apparently healthy nasal mucosa might trigger polyp-growth in chronic rhinosinusitis patients.

The origin of nasal polyps in chronic rhinosinusitis is unknown, but the role of viral infections in polyp growth is clinically well established. Toll-like receptors (TLRs) have recently emerged as key players in our local airway defense against microbes. Among these, TLR9 has gained special interest in viral diseases. Many studies on chronic rhinosinusitis with nasal polyps (CRSwNP) compare polyp tissue with nasal mucosa from polyp-free individuals. Knowledge about changes in the turbinate tissue bordering the polyp tissue is limited.To analyse the role of TLR9 mediated microbial defense in tissue bordering the polyp.Nasal polyps and turbinate tissue from 11 patients with CRSwNP and turbinate tissue from 11 healthy controls in total were used. Five biopsies from either group were analysed immediately with flow cytometry regarding receptor expression and 6 biopsies were used for in vitro stimulation with a TLR9 agonist, CpG. Cytokine release was analysed using Luminex. Eight patients with CRSwNP in total were intranasally challenged with CpG/placebo 24 hours before surgery and the biopsies were collected and analysed as above.TLR9 expression was detected on turbinate epithelial cells from healthy controls and polyp epithelial cells from patients, whereas TLR9 was absent in turbinate epithelial cells from patients. CpG stimulation increased the percentage cells expressing TLR9 and decreased percentage cells expressing VEGFR2 in turbinate tissue from patients. After CpG stimulation the elevated levels of IL-6, G-CSF and MIP-1β in the turbinate tissue from patients were reduced towards the levels demonstrated in healthy controls.Defects in the TLR9 mediated microbial defense in the mucosa adjacent to the anatomic origin of the polyp might explain virus induced polyp growth. CpG stimulation decreased VEGFR2, suggesting a role for CpG in polyp formation. The focus on turbinate tissue in patients with CRSwNP opens new perspectives in CRSwNP-research

The SP‐TLR axis, which locally primes the nasal mucosa, is impeded in patients with allergic rhinitis

Abstract Background Substance P (SP) and toll‐like receptors (TLRs) contribute to airway disease, particularly during viral infection. We recently demonstrated that SP can act as an initial response to viral stimuli in the upper airway by upregulating TLRs in the nasal epithelia (the SP‐TLR axis). Patients with allergic rhinitis (AR) suffer from prolonged airway infections. The aim of the present study was to examine if patients with AR exhibit a disturbance in the SP‐TLR axis. Method Human nasal biopsies and human nasal epithelial cells (HNEC) from healthy volunteers and patients with AR were cultured in the presence of SP. Epithelial expression of TLR4, neutral endopeptidase (NEP) and neurokinin 1 (NK1) were evaluated with flow cytometry and/or quantitative polymerase chain reaction after 30 min to 24 h. The effect of SP on nasal lipopolysaccharide‐induced interleukin‐8 (IL‐8) release was investigated. Results SP stimulation of tissue from healthy volunteers resulted in a transient increase of the TLR4 expression, whereas stimulation of AR patient‐derived material led to a delayed and prolonged upregulation of TLR4. NEP expression in HNEC was lower in AR than healthy controls whereas NK1 receptor expression was increased. SP pretreatment increased TLR4‐dependent IL‐8 expression in healthy controls, but not in AR. Conclusions SP‐induced regulation of TLR4 in the human nasal mucosa is disturbed in AR. An altered SP‐mediated innate immune response may contribute to the dysfunctional and often prolonged responses to infection in AR

LEAP-2, LL-37 and RNase7 in tonsillar tissue: downregulated expression in seasonal allergic rhinitis.

In the upper airway, the production of antimicrobial peptides (AMPs) protects against bacteria, viruses and fungi. Previous investigations have revealed downregulated expression of AMPs in different manifestations of allergic disease. In this study, we examined the expression of LL-37, RNase7 and LEAP-2 in tonsillar tissue and studied a possible relation to seasonal allergic rhinitis (SAR)