Hypersecretion of airway mucus is a characteristic feature of chronic airway diseases like cystic fibrosis (CF) and leads via impairment of the muco-ciliary clearance and bacterial superinfection to respiratory failure. The major components of the mucus matrix forming family of mucins in the airways are MUC5AC and MUC5B. To investigate the expression of these glycoproteins in CF, immunohistochemistry was carried out on trachea, bronchi and peripheral lung obtained from CF patients and compared to normal lung tissues. MUC5AC immunohistochemistry demonstrated signals in goblet cells of the epithelial lining. Also, goblet cells inside glandular secretory ducts revealed MUC5AC-positive staining. In comparison to those from normal subjects, CF sections were characterized by inflammatory changes and goblet cell hyperplasia, resulting in increased numbers of MUC5AC-positive cells. Immunohistochemical staining for MUC5B showed abundant staining of submucosal glands and epithelial goblet cells. Inside the glands, the immunoreactivity was restricted to glandular mucous cells. MUC5AC and MUC5B are expressed in the same histological pattern in CF compared to normal tissues with an increase of MUC5AC-positive cells due to goblet cell hyper- and metaplasia.

The expression of MUC5AC and MUC5B shares a similar distribution to normal airways in different states of asthma. The distribution is not affected by topical corticosteroid therapy.

Th2 T cell immune-driven inflammation plays an important role in allergic asthma. We studied the effect of counterbalancing Th1 T cells in an asthma model in Brown Norway rats that favors Th2 responses. Rats received i.v. transfers of syngeneic allergen-specific Th1 or Th2 cells, 24 h before aerosol exposure to allergen, and were studied 18–24 h later. Adoptive transfer of OVA-specific Th2 cells, but not Th1 cells, and OVA, but not BSA exposure, induced bronchial hyperresponsiveness (BHR) to acetylcholine and eosinophilia in a cell number-dependent manner. Importantly, cotransfer of OVA-specific Th1 cells dose-dependently reversed BHR and bronchoalveolar lavage (BAL) eosinophilia, but not mucosal eosinophilia. OVA-specific Th1 cells transferred alone induced mucosal eosinophilia, but neither BHR nor BAL eosinophilia. Th1 suppression of BHR and BAL eosinophilia was allergen specific, since cotransfer of BSA-specific Th1 cells with the OVA-specific Th2 cells was not inhibitory when OVA aerosol alone was used, but was suppressive with OVA and BSA challenge. Furthermore, recipients of Th1 cells alone had increased gene expression for IFN-γ in the lungs, while those receiving Th2 cells alone showed increased IL-4 mRNA. Importantly, induction of these Th2 cytokines was inhibited in recipients of combined Th1 and Th2 cells. Anti-IFN-γ treatment attenuated the down-regulatory effect of Th1 cells. Allergen-specific Th1 cells down-regulate efferent Th2 cytokine-dependent BHR and BAL eosinophilia in an asthma model via mechanisms that depend on IFN-γ. Therapy designed to control the efferent phase of established asthma by augmenting down-regulatory Th1 counterbalancing mechanisms should be effective.

The nature of protein breakdown products and peptidomimetic drugs such as beta-lactams is crucial for their transmembrane transport across apical enterocyte membranes, which is accomplished by the pH-dependent high-capacity oligopeptide transporter PEPT1. To visualize oligopeptide transporter-mediated uptake of oligopeptides, an ex vivo assay using the fluorophore-conjugated dipeptide derivative D-Ala-Lys-N(epsilon)-7-amino-4-methylcoumarin-3-acetic acid (D-Ala-Lys-AMCA) was established in the murine small intestine and compared with immunohistochemistry for PEPT1 in murine and human small intestine. D-Ala-Lys-AMCA was accumulated by enterocytes throughout all segments of the murine small intestine, with decreasing intensity from the top to the base of the villi. Goblet cells did not show specific uptake. Inhibition studies revealed competitive inhibition by the beta-lactam cefadroxil, the angiotensin-converting enzyme inhibitor captopril, and the dipeptide glycyl-glutamine. Controls were performed using either the inhibitor diethylpyrocarbonate or an incubation temperature of 4 degrees C to exclude unspecific uptake. Immunohistochemistry for PEPT1 localized immunoreactivity to the enterocytes, with the highest intensity at the apical membrane. This is the first study that visualizes dipeptide transport across the mammalian intestine and indicates that uptake assays using D-Ala-Lys-AMCA might be useful for characterizing PEPT1-specific substrates or inhibitors.

The data in the present study demonstrated the localization of the two major respiratory mucin proteins in human nasal mucosa with a similar distribution of expression of MUC5AC and MUC5B in normal upper and lower airways. Mucin protein expression parallels that of mucin messenger RNA expression.

Aims To establish whether enantioselective metabolism of racemic (rac)-salbutamol occurs in the lungs by determining its enantiomeric disposition following inhalation, in the absence and presence of oral charcoal, compared with that following the oral and intravenous routes. Methods Fifteen healthy subjects (eight male) were randomized into an open design, crossover study. Plasma and urine salbutamol enantiomer concentrations were measured for 24 h following oral (2 mg ) with or without oral charcoal (to block oral absorption), inhaled (MDI; 1200 mg ) with or without oral charcoal and intravenous (500 mg) rac-salbutamol. Systemic exposure ( plasma AUC(0,2) and urinary excretion (Au 24h ) of both enantiomers were calculated, and relative exposure to (R)-salbutamol both in plasma (AUC (R)-/AUC (S)-) and urine (Au (R)-/Au (S)-) was derived for each route. Relative exposure after the inhaled with charcoal and oral routes were compared with the intravenous route. Similar results were found when relative exposure was analysed using Au 24h . Conclusions These results show no evidence of significant enantioselective presystemic metabolism in the lungs, whilst confirming it in the gut and systemic circulation, indicating that the (R)-and (S)-enantiomers are present in similar quantities in the airways following inhaled rac-salbutamol.

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(OA) or saline exposure of sensitized Brown Norway rats was examined on agonist reactivity, airway smooth muscle (ASM) content, and contractile protein expression in small bronchioles at 24 h, 7 days, and 35 days after challenge. OA increased ASM content (P Ͻ 0.05 vs. saline) at 24 h, which resolved by 7 days. Maximum developed tension (Tmax) to carbachol, KCl, and 4-␤-phorbol 12,13-dibutyrate was increased (P Ͻ 0.05) by OA in bronchioles at 24 h but was abrogated after correction for ASM. Differences in Tmax were not present at 7 days. In contrast, at 35 days, T max was increased (P Ͻ 0.05) after correction for ASM. Smooth muscle (sm)-␣-actin, sm-myosin heavy chain (MHC) isoform 1, calponin, smoothelin-A, and sm-myosin light chain kinase expression were reduced (P Ͻ 0.05) by OA at 24 h in bronchioles but not in trachealis. Consistent with contraction findings, no difference in expression of these proteins was detected at 7 days. At 35 days, however, with the exception of sm-␣-actin, their abundance was again reduced (P Ͻ 0.05) by OA. Nonmuscle MHC and ␤-actin were unchanged throughout by OA. These findings indicate persistent changes in contractile protein content, consistent with ASM phenotypic modulation in vivo, which occur in response to repeated OA inhalation. Thus, OA exposure induces structural changes in bronchiole ASM content and in agonist responsiveness ex vivo that resemble remodeling in asthma. asthma; inflammation; airway wall structural remodeling ASTHMA IS A DISORDER that affects the tracheobronchial tree from large to small airways (22). One of the basic characteristics of asthma is airway hyperresponsiveness (AHR) that is demonstrated by increased responses to inhaled bronchoconstrictors such as methacholine and that can be observed following allergen exposure. Induction and perpetuation of AHR may result from repeated inflammatory events involving a complex and coordinated response of multiple inflammatory and structural cells, mediators, connective tissue elements, and cytokines whose actions lead ultimately to persistent changes in airway wall structure (5). This remodeling includes epithelial cell damage and mucus gland hypertrophy, reticular basement membrane thickening, alterations in connective tissue composition, and an increase in the content of smooth muscle in the airway wall as a result of hyperplasia and hypertrophy (5).Differentiation of smooth muscle in the developing lung is characterized, as in other tissues, by the progressive replacement of nonmuscle cytoskeletal and contractile proteins with smooth muscle-specific isoforms, leading to a range of distinctive smooth muscle cell phenotype subpopulations (25,27,37). In intact, healthy mature blood vessels and airways, the majority of smooth muscle cells exist in a quiescent and fully differentiated contractile phenotype. Little attention has so far been paid to modulation of the contractile state in airway disease, although parallels in airway and pulmonary vascular remodeling are increasingly being sought (4,16,18,37). In vi...