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Biomedical subjects

Q Hamid

Publications and source records attributed to Q Hamid.

At least 19 recordsLinked to original sources
PubMed2006

Differences in proteoglycan deposition in the airways of moderate and severe asthmatics.

Excess deposition of proteoglycans (PGs) has been described in the subepithelial layer of the asthmatic airway wall. However, less is known about deposition in the airway smooth muscle (ASM) layer, and whether the pattern of deposition is altered depending upon disease severity. Endobronchial biopsies were performed in patients with severe or moderate asthma (defined using American Thoracic Society criteria) and in control subjects. Biopsies were immunostained for the PGs biglycan, lumican, versican and decorin. PG deposition was measured in the subepithelial and ASM layers, the former by calculating the area of positive staining, and the latter by determining the percentage area stained using point counting. Immunostaining for PGs was prominent in biopsies from both moderate and severe asthmatics, compared with control subjects. While there was no difference in the amount of PG in the subepithelial layer between the two asthmatic groups, the percentage area of biglycan and lumican staining in the ASM layer was significantly greater in moderate versus severe asthmatics. Differences in the deposition of proteoglycans within the airway smooth muscle layer of moderate versus severe asthmatics potentially impact on the functional behaviour of the airway smooth muscle in these two groups of patients.

Adult↗
PubMed2006

Signal transducer and activator of transcription 6 down-regulates toll-like receptor-4 expression of a monocytic cell line.

BACKGROUND: Toll-like receptor 4 (TLR4), part of the bacterial lipopolysaccharide (LPS) receptor, is an important bridge between innate and adaptive immunity. Our previous studies have indicated reduced expression of TLR4 and reduced responsiveness to LPS in nasal mucosa of atopic adults compared with non-atopic adults. IL-4 and signal transducer and activator of transcription 6 (STAT6), which are increased in atopic patients, may have a role in modulating TLR4. OBJECTIVE: To examine direct effects of IL-4 and STAT6 on TLR4 expression of U-937 monocytic cells. METHODS: LPS responsiveness, under different conditions of U-937 cells was measured by nuclear factor (NF)-kappaB activation of transcription. TLR4 mRNA was quantified by real-time PCR and TLR4 surface expression was measured by flow cytometry. The promoter and 4.3 kb of the upstream region of TLR4 were cloned into a plasmid vector and transiently transfected into U-937 cells. Transfected cells were incubated with IL-4 and transcriptional activity was assayed by the luciferase assay. STAT6 was transfected to evaluate overexpression of this transcription factor. Cells were also incubated with Tyrphostin AG490 to inhibit tyrosine kinases. RESULTS: NF-kappaB activation by LPS was inhibited by IL-4 pre-incubation but not when IL-4 was added at the same time as LPS. TLR4 mRNA expression was inhibited by IL-4 as early as 6 h but the effect was lost by 24 h. Surface expression of TLR4 was inhibited by IL-4 at 12 and 24 h, but returned to baseline at 48 h. IL-4 inhibited activity of the TLR4 promoter as early as 6 h, but, like the mRNA, these effects were transient. STAT6 overexpression enhanced the inhibition of the TLR4 promoter and prolonged it. Inhibition of TLR4 by IL-4 was abolished by pre-incubation with the tyrosine kinase inhibitor Tyrphostin AG490. CONCLUSION: Our findings demonstrate that IL-4, through STAT6, can modulate TLR4 expression and suggests that Th2 cytokines can impact on the LPS responsiveness of cells.

Adult↗
PubMed2006

Diagnosis and treatment of atopic dermatitis in children and adults: European Academy of Allergology and Clinical Immunology/American Academy of Allergy, Asthma and Immunology/PRACTALL Consensus Report.

There are remarkable differences in the diagnostic and therapeutic management of atopic dermatitis practiced by dermatologists and pediatricians in different countries. Therefore, the European Academy of Allergy and Clinical Immunology and the American Academy of Allergy, Asthma and Immunology nominated expert teams who were given the task of finding a consensus to serve as a guideline for clinical practice in Europe as well as in North America. The consensus report is part of the PRACTALL initiative, which is endorsed by both academies.

Adult↗
PubMed2004

The expression of stem cell factor and c-kit receptor in human asthmatic airways.

BACKGROUND: Asthmatic airways are characterized by infiltration with a variety of inflammatory cells such as mast cells and eosinophils. Stem cell factor (SCF) is an important activating and chemotactic factor for both mast cells and eosinophils. In addition, it is a critical growth and differentiation factor for mast cells. OBJECTIVES: To investigate the contribution of SCF to the pathogenesis of asthma, we examined the expression of SCF and its receptor c-kit in bronchial biopsies and bronchoalveolar lavage (BAL) specimens obtained from asthmatic subjects (n=13) and non-asthmatic control subjects (n=10). METHODS: SCF and c-kit were detected by in situ hybridization (ISH) and immunocytochemistry (ICC). In order to phenotype the cells expressing SCF and c-kit in asthmatic tissue and BAL cells, combined ISH and ICC were also performed. RESULTS: There was a significant difference (P<0.001) in the SCF mRNA expression in asthmatic airway epithelium (70.38+/-12.33% positive cells) compared with controls (12.7+/-17.21% positive cells). There was also a significant difference in subepithelial SCF-mRNA expression, being higher in asthmatics (P<0.001). A significant difference was also found in c-kit receptor mRNA expression in asthmatic biopsies both in epithelium (P<0.001) and subepithelium (P<0.05) compared with controls. ICC results were consistent with the ISH for both SCF and c-kit receptor from asthmatics and controls. The SCF and c-kit receptor mRNA and immunoreactivity in cells recovered from bronchial washing were also significantly higher in asthmatics compared with controls (P<0.05). While SCF expression was localized predominantly in the epithelial layer in bronchial biopsy tissues, alveolar macrophages were found to be the major source of SCF in bronchial washing from asthmatic subjects. CONCLUSION: The results of this study demonstrate the increased expression of SCF and its receptor, c-kit within human asthmatic airways, which suggests an important role of this cytokine in the pathophysiology of asthma.

Adult↗
PubMed2004

Mechanical strain enhances proteoglycan message in fibroblasts from asthmatic subjects.

BACKGROUND: Remodelling of the asthmatic airway includes increased deposition of proteoglycan (PG) molecules. One of the stimuli driving airway remodelling may be excessive mechanical stimulation. OBJECTIVE: We hypothesized that fibroblasts from asthmatic patients would respond to excessive mechanical strain with up-regulation of message for PGs. METHODS: We obtained fibroblasts from asthmatic patients (AF) and normal volunteers (NF) using endobronchial biopsy. Cells were maintained in culture until the fifth passage and then grown on a flexible collagen-coated membrane. Using the Flexercell device, cells were then subjected to cyclic stretch at 30% amplitude at 1 Hz for 24 h. Control cells were unstrained. Total RNA was extracted from the cell layer and quantitative RT-PCR performed for decorin, lumican and versican mRNA. RESULTS: In unstrained cells, the expression of decorin mRNA was greater in AF than NF. With strain, NF showed increased expression of versican mRNA and AF showed increased expression of versican and decorin mRNA. The relative increase in versican mRNA expression with strain was greater in AF than NF. CONCLUSIONS: These data support the hypothesis that proteoglycan message is increased in asthmatic fibroblasts subject to mechanical strain. This finding has implications for the mechanisms governing airway wall remodelling in asthma.

Adult↗
PubMed2004

Fractional analysis of Th2-type cytokines in sequential samples of induced sputum.

BACKGROUND: Recent studies have demonstrated the usefulness of induced sputum in detecting the expression of Th2-type cytokines in asthmatics and have shown that the profile of inflammatory cells in induced sputum differs with time. OBJECTIVE: To determine whether the duration of sputum induction also affects the expression of Th2-type cytokines in induced sputum. METHODS: Induced sputum was collected from eight atopic asthmatics at two separated intervals (5 min each) during a 15 min sputum induction, and each sample was examined separately for cytokine expression and inflammatory cells. Using immunocytochemistry, interleukin (IL)-4 and IL-5 immunoreactivity, T lymphocytes (CD3), eosinophils (major basic protein), neutrophils (elastase), epithelial cells and macrophages (CD68) were compared in the induced sputum obtained from the 0 min to 5 min and the 10 min to 15 min samples. RESULTS: The number of immunoreactive-positive cells expressing IL-4 and IL-5 were significantly higher in the 10 to 15 min induced sputum sample than in the 0 min to 5 min induced sputum sample (P<0.05). The number of eosinophils was also significantly higher in the 10 min to 15 min sample than in the 0 min to 5 min sample (P<0.05). In contrast, the number of neutrophils was significantly higher in the 0 min to 5 min sample than in the 10 min to 15 min sample (P<0.01); T lymphocytes, macrophages and epithelial cells did not differ between the two samples. CONCLUSION: This study demonstrates that the duration of sputum induction significantly affects the profile of inflammatory cells and Th2-type cytokine expression, and underscores the need for the standardization of induced sputum procedure.

Adult↗
PubMed2004

Expression of HCLCA1 in cystic fibrosis lungs is associated with mucus overproduction.

Mucus overproduction is typical in cystic fibrosis (CF) airway disease. The human calcium-activated chloride channel, hCLCA1, has been reported to be upregulated by interleukin (IL)-9 and to regulate the expression of mucins. Therefore, the expression of IL-9, IL-9 receptor (IL-9R) and hCLCA1 between the lungs of CF patients and healthy control subjects was compared. Endoscopic biopsy samples of bronchial mucosa from 10 CF patients and six control subjects were stained with periodic acid-Schiff. IL-9, IL-9R and hCLCA1 expression was determined by immunocytochemistry. Expression of hCLCA1 mRNA was also determined by in situ hybridisation. The present study found significant increases in IL-9, IL-9R and hCLCA1 immunoreactivity, hCLCA1 mRNA expression, and numbers of mucus-producing cells in the mucosa of CF patients compared to control subjects. Positive correlations were found between IL-9R-positive-cells with IL-9-positive cells and hCLCA1-positive cells, and between PAS-positive cells with hCLCA1-positive cells and IL-9R-positive cells. Expression of hCLCA1 mRNA was colocalised with IL-9R expression and PAS-positive staining in epithelial cells. Increased expression of interleukin-9 and interleukin-9 receptor, as well as an upregulation of the human calcium-activated chloride channel, hCLCA1, in mucus-producing epithelium of cystic fibrosis patients, support the hypothesis that interleukin-9 contributes to mucus overproduction in cystic fibrosis airway disease.

Case-Control Studies↗
PubMed2003

Regulation of procollagen I (alpha1) by interleukin-4 in human bronchial fibroblasts: a possible role in airway remodelling in asthma.

BACKGROUND: In bronchial mucosa, T cells are in close association with fibroblasts. This cell contact raises the possibility of cross-talk between the two cell types through cytokines, such as interleukin-4 (IL-4). OBJECTIVE: We postulated that IL-4 may modulate collagen synthesis and degradation in the fibroblasts of asthmatics. METHODS: Bronchial fibroblasts from asthmatics (BAF) and normal controls (BNF) were stimulated with IL-4. Procollagen I gene expression and protein production were measured by real-time PCR, RT-PCR, and radioimmunoassay. The effect of IL-4 on the regulation of procollagen I (alpha1) promoter was studied through transient cell transfections. The implication of Sp1 and AP-1 in regulating IL-4-induced procollagen I (alpha1) production was determined. The effect of IL-4 on metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-2 (TIMP-2) production and gene expression was evaluated. RESULTS: Following IL-4 stimulation, there was a significant increase in the expression of mRNA of procollagen I (alpha1) by human bronchial fibroblasts of asthmatics and controls. IL-4 has a dose-response effect on mRNA, with a maximal effect at 5 ng/mL, as determined by real-time PCR. The maximal increase in procollagen I (alpha1) was observed at 6 h after IL-4 stimulation in both BNF and BAF. BAFs have a greater increase in the procollagen I (alpha1)/beta2 microglobulin ratio after 6 h of IL-4 stimulation (4.1 x 10-2+/-0.03 to 20.8 x 10-2+/-0.1) compared with BNF (2.9 x 10-2+/-0.006 to 9.2 x 10-2+/-0.08) (P=0.001). In transient transfection experiments, IL-4 increased promoter activity by threefold in BAF and BNF. Sp1 was up-regulated after IL-4 stimulation and AP-1 was down-regulated as shown by electrophoretic mobility shift assay. IL-4 decreased MMP-2 protein and mRNA levels, and did not alter TIMP-2 production. CONCLUSIONS: IL-4 positively regulates procollagen I (alpha1) transcription by direct promoter activation and increases the TIMP-2/MMP-2 ratio, thereby supporting the profibrotic effect of this cytokine. Thus, this study emphasizes that IL-4 may be considered as a link between inflammation and collagen deposition observed in asthmatic airways.

Asthma↗
PubMed2002

Bronchial inflammation in corticosteroid-sensitive and corticosteroid-resistant asthma at baseline and on oral corticosteroid treatment.

BACKGROUND: Pathophysiology of corticosteroid (CS)-resistant asthma remains incompletely understood. OBJECTIVE: To determine if failure of asthma to clinically improve with CS is due to a defective response of airway bronchial inflammation to these drugs. METHODS: Twenty-one asthmatics having a decreased baseline FEV1 that improved >or= 30% with inhaled beta2 agonist got bronchial biopsies before and at the end of an oral CS treatment (methylprednisolone 40 mg daily for 14 days). They were arbitrarily divided into two groups according to baseline FEV1 improvement following this treatment: >or= 23% designated as CS-sensitive (CSS) (n = 10) and < 15% as CS-resistant (CSR) (n = 11). RESULTS: Before oral CS, counts of bronchial mucosa inflammatory cells identified by immunohistochemistry (CD3, MBP, tryptase, CD68, neutrophil elastase and CD25 for lymphocytes, eosinophils, mast cells, macrophages, neutrophils and IL-2 receptors, respectively) were similar in CSS and CSR subjects. Oral CS decreased CD3+ cell counts (medians: 60-20 cells/mm(2); P = 0.014) and MBP+ cell counts (medians: 19-4 cells/mm(2); P = 0.03) in CSS asthmatics, but only tryptase+ cell counts in CSR asthmatics (medians: 30-18 cells/mm(2); P = 0.05). Few bronchial neutrophil elastase+ cells were observed and their counts were similar in the two groups of asthmatics before and when on oral CS (all medians: = 2 cells/mm(2)). CONCLUSIONS: These data show that, in these subjects with moderate to severe asthma, lymphocytes and eosinophils constitute most of the inflammatory cells infiltrating the bronchial mucosa. They also demonstrated that clinical impaired response to CS is associated with a persistent bronchial mucosa cellular infiltrate despite oral CS treatment. Additional studies are required to determine the role of this CS-resistant bronchial inflammation in the impaired asthma clinical response to these drugs.

Administration, Inhalation↗
PubMed2001

Airway inflammation and remodeling in asthma. Lessons from interleukin 11 and interleukin 13 transgenic mice.

Noninflammatory structural alterations, variously referred to as airway remodeling, are well documented in the asthmatic airway. However, the pathogenesis of these alterations, the importance of airway remodeling in generating the asthma phenotype, and the natural history of airway remodeling responses have not been adequately defined. Because exaggerated cytokine production is a characteristic feature of the asthmatic airway, we used constitutive and inducible overexpression transgenic systems to investigate the contributions that interleukin 11 (IL-11) and IL-13 might make to airway remodeling responses. These studies demonstrated that both cytokines produce responses in the murine airway with features similar to those in human asthmatic tissues. IL-11 caused airway fibrosis with the enhanced accumulation of interstitial collagens, myocytes, and myofibroblasts. IL-13 caused mucous metaplasia, enhanced mucin gene expression, enhanced tissue hyaluronic acid accumulation, and subepithelial fibrosis. Importantly, IL-11 was detected most readily in tissues from asthmatic subjects with severe airway remodeling that was similar to that seen in the IL-11 transgenic mice. In addition, IL-11 was shown to inhibit asthma-like inflammation while stimulating airway fibrosis. This suggests that IL-11 elaboration is, in part, an attempt at airway healing. Last, a novel triple transgenic system is described that allows transgene expression to be regulated in a true "on/off" manner. This system may be useful in defining the reversibility of transgene-induced airway remodeling responses.

Animals↗
PubMed2001

Eosinophil peroxidase mediates protein nitration in allergic airway inflammation in mice.

The eosinophilic inflammatory response in asthma is associated with protein nitration, detected as immunostaining for 3-nitrotyrosine (3NT). As the presence of 3NT is strongly correlated with upregulation of the inducible form of nitric oxide synthase (NOS II), it has been hypothesized that 3NT formation results from the action of peroxynitrite (ONOO-), a highly reactive NO derivative produced from the reaction of molecular NO and O2-. However, recent observations have suggested that the action of peroxidases, including eosinophil peroxidase (EPO), may be responsible for protein nitration. In this study, we used murine models of allergic asthma to address the relative contribution of EPO and NOS II to protein nitration. We studied EPO-deficient New Zealand White (NZW) mice, which were sensitized and challenged intranasally with ovalbumin (OVA). Despite comparable levels of eosinophilia, NO, and superoxide production, NZW mice exhibited markedly decreased 3NT staining around the airways after OVA challenge when compared with two other strains (A/J and C57BL/6J). Immunocytochemical analysis of bronchoalveolar lavage (BAL) cells and lung sections suggested that 3NT staining was largely confined to eosinophils. This was confirmed by Western Blot analysis of proteins from different subsets of BAL cells that demonstrated a marked decrease in 3NT formation in eosinophils from NZW mice. These results contrast with those obtained in OVA-sensitized and -challenged NOS II deficient mice, which despite decreased NO production, exhibited similar 3NT staining in the airways after OVA challenge as in wild-type control mice. In this model, protein nitration was thus not a function of NO production by NOS II. We conclude that in the mouse, 3NT formation after specific allergen challenge is dependent on EPO activity, particularly in eosinophils themselves. In contrast, 3NT formation is not driven by upregulation of NOS II expression in this model and does not appear to depend on increases in the level of NO production.

Animals↗
PubMed2001

Small airway inflammation in asthma.

Asthma was originally described as an inflammatory disease that predominantly involves the central airways. Pathological and physiological evidence reported during the past few years suggests that the inflammatory process extends beyond the central airways to the peripheral airways and the lung parenchyma. The small airways are capable of producing T-helper-2 cytokines, as well as chemokines, and they have recently been recognized as a predominant site of airflow obstruction in asthmatic persons. The inflammation at this distal site has been described as more severe than large airway inflammation. These findings are of great clinical significance, and highlight the need to consider the peripheral airways as a target in any therapeutic strategy for treatment of asthma.

Animals↗
PubMed2001

Functional expression of IL-12 receptor by human eosinophils: IL-12 promotes eosinophil apoptosis.

In murine models of allergic inflammation, IL-12 has been shown to decrease tissue eosinophilia, but the underlying mechanisms are not known. We evaluated the expression of IL-12R and the effect of IL-12 on eosinophil survival. In situ hybridization demonstrated the presence of mRNA and immunoreactivity for IL-12Rbeta1 and -beta2 subunits in human peripheral blood eosinophils. Surface expression of IL-12Rbeta1 and -beta2 subunits on freshly isolated human eosinophils was optimally expressed after incubation with PMA. To determine the functional significance of IL-12R studies, we studied cell viability and apoptosis. Morphological analysis and propidium iodide staining for cell cycle demonstrated that recombinant human IL-12 increased in vitro human eosinophil apoptosis in a dose-dependent manner. Addition of IL-5 together with IL-12 abrogated eosinophil apoptosis, suggesting that IL-12 and IL-5 have antagonistic effects. Our findings provide evidence for a novel role for IL-12 in regulating eosinophil function by increasing eosinophil apoptosis.

Apoptosis↗
PubMed2001

Functional expression of IL-9 receptor by human neutrophils from asthmatic donors: role in IL-8 release.

Human polymorphonuclear neutrophils (PMNs) express surface receptors for various inflammatory mediators, including IgE and IL-4. Recently, the IL-9R locus has been genetically linked to asthma and bronchial hyperresponsiveness in humans. In this study, we evaluated expression of the IL-9R and the effect of IL-9 on human PMNs. RT-PCR analysis showed the presence of IL-9Ralpha-chain mRNA in PMN RNA preparations from asthmatic patients. Using FACS analysis, surface expression of IL-9Ralpha was detected on PMNs freshly isolated from asthmatics, and to a lesser extent on normal controls. In addition, protein expression of IL-9Ralpha was also detected in peripheral blood and bronchoalveolar lavage PMNs. Furthermore, functional studies showed that IL-9 stimulation of PMNs results in the release of IL-8 in a concentration-dependent manner. The anti-IL-9 neutralizing Ab suppressed this effect, but had no effect on GM-CSF-induced IL-8 release from PMNs. Taken together, these findings suggest a novel role for PMNs in allergic disease through the expression and activation of the IL-9R.

Asthma↗
PubMed2001

Regulation of allergic airways inflammation by cytokines and glucocorticoids.

Cytokines mediate the allergic inflammatory response of the airways, and glucocorticosteroids ameliorate allergy symptoms by regulating cytokine expression. Recent studies provide insight into the manner by which cytokines work together to mediate allergic airway disease. Real progress has also been gained in our understanding of subcellular mechanisms of allergic inflammation, particularly the role of transcription factors in regulating the expression of specific cytokine profiles and the differentiation of the TH2 subset. This article provides an update of recently reported findings in this field and highlights emerging concepts of allergic inflammation.

Animals↗