Arf6 regulates energy metabolism in neutrophils

The small GTPase Arf6 regulates many cellular processes, including cytoskeletal remodeling, receptor endocytosis, and pathogen phagocytosis. Arf6 silencing in neutrophil (PMN)-like cells is well-known to inhibit chemotactic peptide-mediated activation of phospholipase D, the oxidative burst, and β2 integrin-dependent adhesion. In conditional knockout (cKO) mice, the migration to inflammatory sites of Arf6-deficient PMNs was diminished and associated with reduced cell surface expression of β2 integrins. In this study we assessed the impact of Arf6 depletion on the functions and gene expression profile of PMNs isolated from the mouse air pouch. Numerous genes involved in response to oxygen levels, erythrocyte and myeloid differentiation, macrophage chemotaxis, response to chemicals, apoptosis, RNA destabilization, endosome organization, and vesicle transport were differentially expressed in PMNs cKO for Arf6. Lpar6 and Lacc-1 were the most up-regulated and down-regulated genes, respectively. The deletion of Arf6 also decreased Lacc-1 protein level in PMNs, and silencing of Arf6 in THP-1 monocytic cells delayed LPS-mediated Lacc-1 expression. We report that fMLP or zymosan-induced glycolysis and oxygen consumption rate were both decreased in air pouch PMNs but not in bone marrow PMNs of Arf6 cKO mice. Reduced oxygen consumption correlated with a decrease in superoxide and ROS production. Deletion of Arf6 in PMNs also reduced phagocytosis and interfered with apoptosis. The data suggest that Arf6 regulates energy metabolism, which may contribute to impaired phagocytosis, ROS production, and apoptosis in PMN-Arf6 cKO. This study provides new information on the functions and the inflammatory pathways influenced by Arf6 in PMNs.

Deletion of S100a8 and S100a9 Enhances Skin Hyperplasia and Promotes the Th17 Response in Imiquimod-Induced Psoriasis

High concentrations of the damage-associated molecular patterns S100A8 and S100A9 are found in skin and serum from patients suffering from psoriasis, an IL-17-related disease. Notably, although the expression of these proteins correlates with psoriatic disease severity, the exact function of S100A8 and S100A9 in psoriasis pathogenesis remains unclear. In this study, we investigated the role of S100A8 and S100A9 in psoriasis-associated skin hyperplasia and immune responses using S100a8-/- and S100a9-/- mice in an imiquimod-induced model of psoriasis. We found that S100a8-/- and S100a9-/- psoriatic mice exhibit worsened clinical symptoms relative to wild-type mice and increased expression of S100A9 and S100A8 proteins in keratinocytes, respectively. In addition, the loss of S100A8 enhances proliferation of keratinocytes and disrupts keratinocyte differentiation. We further detected elevated production of IL-17A and -F from CD4+ T cells in the absence of S100A8 and S100A9, as well as increased infiltration of neutrophils in the skin. In addition, treatment with anti-IL-17A and -F was found to reduce psoriasis symptoms and skin hyperplasia in S100a8-/- and S100a9-/- mice. These data suggest that S100A8 and S100A9 regulate psoriasis by inhibiting production of IL-17A and -F, thereby, to our knowledge, providing new insights into their biological functions.

Enhanced myelopoiesis and aggravated arthritis in S100a8-deficient mice

Expressed strongly by myeloid cells, damage-associated molecular pattern (DAMP) proteins S100A8 and S100A9 are found in the serum of patients with infectious and autoimmune diseases. Compared to S100A9, the role of S100A8 is controversial. We investigated its biological activity in collagen-induced arthritis using the first known viable and fertile S100a8-deficient (S100a8^-/-) mouse. Although comparable to the wild type (WT) in terms of lymphocyte distribution in blood and in the primary and secondary lymphoid organs, S100a8^-/- mice had increased numbers of neutrophils, monocytes and dendritic cells in the blood and bone marrow, and these all expressed myeloid markers such as CD11b, Ly6G and CD86 more strongly. Granulocyte-macrophage common precursors were increased in S100a8^-/- bone marrow and yielded greater numbers of macrophages and dendritic cells in culture. The animals also developed more severe arthritic disease leading to aggravated osteoclast activity and bone destruction. These findings were correlated with increased inflammatory cell infiltration and cytokine secretion in the paws. This study suggests that S100A8 is an anti-inflammatory DAMP that regulates myeloid cell differentiation, thereby mitigating the development of experimental arthritis.

The use of leukocytes' secretome to individually target biological therapy in autoimmune arthritis: a case report

Background

Biological agents have allowed remarkable improvement in controlling autoimmune arthropathies, although none of the numerous biologics readily available represent a universal treatment standard. Moreover, classical and genetic predictors are currently unsatisfactory to predict individual response to a biologic, and the best treatment selection is still based on a trial-and-error approach. Here, we report a clinical case demonstrating the usefulness of examining the leukocytes’ secretome of patients. We set up and standardized a protocol that examines a patient’s immune responses to establish the secretome of the blood mononuclear leukocytes and personalize the biotherapy.

Case presentation

A 24-year-old woman was diagnosed with active early rheumatoid arthritis. The initial treatment regimen (prednisone, methotrexate, hydroxychloroquine, naproxen) was inefficient, as well as the anti-TNF adalimumab. The diagnosis was revised as possible rheumatoid arthritis-like psoriatic arthritis and adalimumab was replaced by abatacept (IgG1 Fc-CTLA-4) to no avail. Five years later, abatacept was replaced by the anti-IL-12/IL-23 ustekinumab with no objective control over the symptoms. The patient was thus enrolled in a prospective study based on the quantification of cytokines secreted by peripheral blood leukocytes stimulated with well-known immune activators of pattern recognition receptors and cytokine signalling. The results of this study revealed that plasma concentrations of cytokines were similar between the patient and healthy donors. In comparison to leukocytes from healthy donors, the patient’s secretome showed a unique overproduction of IL-6. The anti-IL-6 receptor tocilizumab was, therefore, administered with a rapid improvement of her active psoriatic arthritis that remained dependent on low prednisone dosage. Clinical parameters progressively returned to normal levels and her quality of life was greatly improved, despite the major delay to begin the present personalized treatment.

Conclusions

An efficient way to effectively treat patients with complex autoimmune arthropathies, and avoid irreversible disability, is to know their leukocytes’ secretome to identify abnormally secreted cytokines and personalize their biotherapy, as exemplified by this case report.

Discoidin domain receptor 1 promotes Th17 cell migration by activating the RhoA/ROCK/MAPK/ERK signaling pathway

Effector T cell migration through the tissue extracellular matrix (ECM) is an important step of the adaptive immune response and in the development of inflammatory diseases. However, the mechanisms involved in this process are still poorly understood. In this study, we addressed the role of a collagen receptor, the discoidin domain receptor 1 (DDR1), in the migration of Th17 cells. We showed that the vast majority of human Th17 cells express DDR1 and that silencing DDR1 or using the blocking recombinant receptor DDR1:Fc significantly reduced their motility and invasion in three-dimensional (3D) collagen. DDR1 promoted Th17 migration by activating RhoA/ROCK and MAPK/ERK signaling pathways. Interestingly, the RhoA/ROCK signaling module was required for MAPK/ERK activation. Finally, we showed that DDR1 is important for the recruitment of Th17 cells into the mouse dorsal air pouch containing the chemoattractant CCL20. Collectively, our results indicate that DDR1, via the activation of RhoA/ROCK/MAPK/ERK signaling axis, is a key pathway of effector T cell migration through collagen of perivascular tissues. As such, DDR1 can contribute to the development of Th17-dependent inflammatory diseases.

Secretion of S100A8, S100A9, and S100A12 by Neutrophils Involves Reactive Oxygen Species and Potassium Efflux

S100A8/A9 (calprotectin) and S100A12 proinflammatory mediators are found at inflammatory sites and in the serum of patients with inflammatory or autoimmune diseases. These cytoplasmic proteins are secreted by neutrophils at sites of inflammation via alternative secretion pathways of which little is known. This study examined the nature of the stimuli leading to S100A8/A9 and S100A12 secretion as well as the mechanism involved in this alternative secretion pathway. Chemotactic agents, cytokines, and particulate molecules were used to stimulate human neutrophils. MSU crystals, PMA, and H2O2 induced the release of S100A8, S100A9, and S100A12 homodimers, as well as S100A8/A9 heterodimer. High concentrations of S100A8/A9 and S100A12 were secreted in response to nanoparticles like MSU, silica, TiO2, fullerene, and single-wall carbon nanotubes as well as in response to microbe-derived molecules, such as zymosan or HKCA. However, neutrophils exposed to the chemotactic factors fMLP failed to secrete S100A8/A9 or S100A12. Secretion of S100A8/A9 was dependent on the production of reactive oxygen species and required K(+) exchanges through the ATP-sensitive K(+) channel. Altogether, these findings suggest that S100A12 and S100A8/A9 are secreted independently either via distinct mechanisms of secretion or following the activation of different signal transduction pathways.

Regulation of TLR3 Activation by S100A9

Recognition of viral dsRNA by endosomal TLR3 activates innate immune response during virus infection. Trafficking of TLR3 to the endolysosomal compartment arising from fusion of late endosome (LE) with lysosome is required for recognition and detection of pathogen associated molecular patterns, which results in activation of the TLR3-dependent signaling cascade. Existing knowledge about the mechanism(s) and cellular factor(s) governing TLR3 trafficking is limited. In the current study, we identified intracellular S100A9 protein as a critical regulator of TLR3 trafficking. S100A9 was required for maturation of TLR3 containing early endosome (EE) into LE, the compartment that fuses with lysosome to form the endolysosomal compartment. A drastic reduction in cytokine production was observed in S100A9-knockout (KO) primary macrophages following RNA virus infection and treatment of cells with polyinosinic-polycytidylic acid (polyIC; a dsRNA mimetic that acts as a TLR3 agonist). Mechanistic studies revealed colocalization and interaction of S100A9 with TLR3 following polyIC treatment. S100A9-TLR3 interaction was critical for maturation of TLR3 containing EE into LE because TLR3 could not be detected in the LE of polyIC-treated S100A9-KO macrophages. Subsequently, TLR3 failed to colocalize with its agonist (i.e., biotin-labeled polyIC) in S100A9-deficient macrophages. The in vivo physiological role of S100A9 was evident from loss of cytokine production in polyIC-treated S100A9-KO mice. Thus, we identified intracellular S100A9 as a regulator of TLR3 signaling and demonstrated that S100A9 functions during pre-TLR3 activation stages by facilitating maturation of TLR3 containing EE into LE.

α2β1 integrin regulates Th17 cell activity and its neutralization decreases the severity of collagen-induced arthritis

Th17 cells play a critical role in the pathogenesis of rheumatoid arthritis (RA), but the mechanisms by which these cells regulate the development of RA are not fully understood. We have recently shown that α2β1 integrin, the receptor of type I collagen, is the major collagen-binding integrin expressed by human Th17 cells. In this study, we examined the role of α2β1 integrin in Th17-mediated destructive arthritis in the murine model of collagen-induced arthritis (CIA). We found that α2β1 integrin is expressed on synovial Th17 cells from CIA mice and its neutralization with a specific mAb significantly reduced inflammation and cartilage degradation, and protected the mice from bone erosion. Blockade of α2β1 integrin led to a decrease in the number of Th17 cells in the joints and to a reduction of IL-17 levels in CIA mice. This was associated with an inhibition of receptor activator of NF-κB ligand levels and osteoclast numbers, and reduction of bone loss. We further show that α2β1 integrin is expressed on synovial Th17 cells from RA patients, and that its ligation with collagen costimulated the production of IL-17 by polarized human Th17 cells by enhancing the expression of retinoic acid receptor-related orphan receptor C through ERK and PI3K/AKT. Our findings provide the first evidence, to our knowledge, that α2β1 integrin is an important pathway in Th17 cell activation in the pathogenesis of CIA, suggesting that its blockade can be beneficial for the treatment of RA and other Th17-associated autoimmune diseases.

An inflammation loop orchestrated by S100A9 and calprotectin is critical for development of arthritis

OBJECTIVE

The S100A9 and S100A8 proteins are highly expressed by neutrophils and monocytes and are part of a group of damage-associated molecular pattern molecules that trigger inflammatory responses. Sera and synovial fluids of patients with rheumatoid arthritis (RA) contain high concentrations of S100A8/A9 that correlate with disease activity.

METHODS

In this study, we investigated the importance of S100A9 in RA by using neutralizing antibodies in a murine lipopolysaccharide-synchronized collagen-induced arthritis model. We also used an in vitro model of stimulation of human immune cells to decipher the role played by S100A9 in leukocyte migration and pro-inflammatory cytokine secretion.

RESULTS

Treatment with anti-S100A9 antibodies improved the clinical score by 50%, diminished immune cell infiltration, reduced inflammatory cytokines, both in serum and in the joints, and preserved bone/collagen integrity. Stimulation of neutrophils with S100A9 protein led to the enhancement of neutrophil transendothelial migration. S100A9 protein also induced the secretion by monocytes of proinflammatory cytokines like TNFα, IL-1β and IL-6, and of chemokines like MIP-1α and MCP-1.

CONCLUSION

The effects of anti-S100A9 treatment are likely direct consequences of inhibiting the S100A9-mediated promotion of neutrophil transmigration and secretion of pro-inflammatory cytokines from monocytes. Collectively, our results show that treatment with anti-S100A9 may inhibit amplification of the immune response and help preserve tissue integrity. Therefore, S100A9 is a promising potential therapeutic target for inflammatory diseases like rheumatoid arthritis for which alternative therapeutic strategies are needed.

Influence of smoking on airway inflammation and remodelling in asthma

BACKGROUND

Although exposure to tobacco smoke has been associated with increased morbidity and mortality, cigarette smoking is still common in the asthmatic population. Induced sputum neutrophilia has been observed in asthmatic smokers, but the effects of regular smoking on their bronchial mucosa morphology remain to be defined. This study documents the inflammatory and remodelling features in bronchial biopsies of smoking compared with non-smoking asthmatics.

METHODS

We analysed bronchial biopsies from 24 steroid-naïve young subjects with mild asthma: 12 non-smoking and 12 currently smoking subjects. In addition to airway morphology assessment, inflammation and remodelling were analysed by immunohistochemistry using antibodies against CD3, CD68, major basic protein, neutrophil elastase, and tryptase. Expression of the cytokines IL-4, IL-5, IL-8, IFN-gamma, transforming growth factor-beta, and TNF was determined by in situ hybridization.

RESULTS

Compared with non-smoking asthmatic subjects, smoking asthmatics' bronchial mucosa showed squamous cell metaplasia, in addition to increased expression of subepithelial neutrophil elastase, IFN-gamma, and intraepithelial IL-8.

CONCLUSIONS

Smoking status modifies morphological and inflammatory processes in young subjects with mild asthma. The changes may possibly affect asthma treatment responses and clinical outcomes.

Induced sputum markers of fibrosis and decline in pulmonary function in asbestosis and silicosis: a pilot study

OBJECTIVE

To evaluate the usefulness of fibrogenic cytokines and mediators in the analysis of induced sputum and determine if their levels correlated with previous decline in lung function in asbestosis and silicosis.

DESIGN

In a pilot study for the evaluation of 19 workers with asbestosis and 15 with silicosis, all workers had chart reviews and records of previous lung function tests. Fourteen healthy control subjects were also included in the study. All subjects attended the laboratory for a clinical evaluation, pulmonary function tests and induced sputum sampling. Differential cell counts were performed and the following mediators and cytokines were measured: matrix metalloproteinase 9 (MMP-9), tissue inhibitor of metalloproteinases 1 (TIMP-1), fibronectin, interleukin 1 beta (IL-1beta), IL-6, IL-8, IL-12, transforming growth factor beta (TGF-beta) and tumor necrosis factor-alpha (TNF-alpha).

RESULTS

Levels of IL-1beta were higher in the sputum of subjects with asbestosis and silicosis than in controls. Eosinophils, neutrophils and IL-1beta levels were significantly correlated with the rate of decline in pulmonary function.

CONCLUSION

The induced sputum levels of certain inflammatory cells and IL-1beta correlate with the decline in pulmonary function associated with asbestosis and silicosis. It remains to be established if these markers can help predict the clinical outcome of workers exposed to these mineral particles or fibers in a prospective study.

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.

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.

Endothelial cells modulate eosinophil surface markers and mediator release

Migration from blood to tissue modulates eosinophil function, possibly through interactions with endothelial cells. The effects of contact with and migration through endothelial cells on eosinophil expression of surface markers and release of leukotriene C4 were evaluated. A small proportion (2.6%) of eosinophils spontaneously migrated through endothelial cell monolayers. Activation of endothelial cells by interleukin (IL)-4 or IL-1beta slightly increased this migration (to 12.4%), which became much greater when a chemoattractant was placed in the lower chamber (84.3%). However, the chemotactic effect was downregulated by pretreating endothelial cells with interferon gamma (IFN-gamma; 63.1%). At baseline, 5% of eosinophils expressed CD69; this increased to 30.7% in culture on untreated endothelial cells and to 50.9% on IL-1beta-pretreated endothelial cells. This effect was mediated through intercellular adhesion molecule-1/CD11b interaction. Eosinophil migration through endothelial cells further increased CD69 expression to 63.9% and also increased CD35 expression from 83.3 to 91.3%. Upon stimulation, eosinophils that had migrated through endothelial cells produced more leukotriene C4 than control cells (872.4 and 103.9 pg x mL(-1), respectively). Endothelial cell pretreatment with IL-4 or IL-1beta further increased leukotriene C4 release (1,789.1 and 2,895.1 pg x mL(-1), respectively), whereas pretreatment with IFN-gamma decreased it (293.7 pg x mL(-1)). These data show that in vitro interactions with endothelial cells upregulate eosinophil membrane receptor expression and mediator release and that these effects are differently modulated by T-helper cell type 1 and 2 cytokines. These eosinophil modulations may play an important role in asthma pathogenesis.

Interleukin-18 and gamma interferon production by oral epithelial cells in response to exposure to Candida albicans or lipopolysaccharide stimulation

Oral candidiasis is a collective name for a group of disorders caused by the dimorphic fungus Candida albicans. Host defenses against C. albicans essentially fall into two categories: specific immune mechanisms and local oral mucosal epithelial cell defenses. Since oral epithelial cells secrete a variety of cytokines and chemokines in response to oral microorganisms and since C. albicans is closely associated with oral epithelial cells as a commensal organism, we wanted to determine whether interleukin-18 (IL-18) and gamma interferon (IFN-gamma) were produced by oral epithelial cells in response to C. albicans infection and lipopolysaccharide (LPS) stimulation. Our results showed that IL-18 mRNA and protein were constitutively expressed by oral epithelial cells and were down-regulated by Candida infections but increased following LPS stimulation. Both C. albicans and LPS significantly decreased pro-IL-18 (24 kDa) levels and increased active IL-18 (18 kDa) levels. This effect was IL-1beta-converting-enzyme dependent. The increase in active IL-18 protein levels promoted the production of IFN-gamma by infected cells. No effect was obtained with LPS. Although produced only at an early stage, secreted IFN-gamma seemed to be a preferential response by oral epithelial cells to C. albicans growth. These results provide additional evidence for the contribution of oral epithelial cells to local (direct contact) and systemic (IL-18 and IFN-gamma production) defense against exogenous stimulation such as C. albicans infection or LPS stimulation.

Systematic genetic analysis with ordered arrays of yeast deletion mutants

In Saccharomyces cerevisiae, more than 80% of the approximately 6200 predicted genes are nonessential, implying that the genome is buffered from the phenotypic consequences of genetic perturbation. To evaluate function, we developed a method for systematic construction of double mutants, termed synthetic genetic array (SGA) analysis, in which a query mutation is crossed to an array of approximately 4700 deletion mutants. Inviable double-mutant meiotic progeny identify functional relationships between genes. SGA analysis of genes with roles in cytoskeletal organization (BNI1, ARP2, ARC40, BIM1), DNA synthesis and repair (SGS1, RAD27), or uncharacterized functions (BBC1, NBP2) generated a network of 291 interactions among 204 genes. Systematic application of this approach should produce a global map of gene function.

IL-17 is increased in asthmatic airways and induces human bronchial fibroblasts to produce cytokines

BACKGROUND

IL-17 is a cytokine that has been reported to be produced by T lymphocytes. In vitro, IL-17 activates fibro-blasts and macrophages for the secretion of GM-CSF, TNF-alpha, IL-1beta, and IL-6. A number of these cytokines are involved in the airway remodeling that is observed within the lungs of asthmatic individuals.

OBJECTIVE

In this study, we investigated the expression of IL-17 in sputum and bronchoalveolar lavage specimens obtained from asthmatic subjects and from nonasthmatic control subjects.

METHODS

IL-17 was detected through use of immunocytochemistry, in situ hybridization, and Western blot. Bronchial fibroblasts were stimulated with IL-17, and cytokine production and chemokine production were detected through use of ELISA and RT-PCR.

RESULTS

Using immunocytochemistry, we demonstrated that the numbers of cells positive for IL-17 are significantly increased in sputum and bronchoalveolar lavage fluids of subjects with asthma in comparison with control subjects (P <.001 and P <.005, respectively). We demonstrated that in addition to T cells, eosinophils in sputum and bronchoalveolar lavage fluids expressed IL-17. Peripheral blood eosinophils were also positive for IL-17, and the level of IL-17 in eosinophils purified from peripheral blood was significantly higher in subjects with asthma than in controls (P <.01). To further investigate the mechanism of action of IL-17 in vivo, we examined the effect of this cytokine on fibroblasts isolated from bronchial biopsies of asthmatic and nonasthmatic subjects. IL-17 did enhance the production of pro-fibrotic cytokines (IL-6 and IL-11) by fibroblasts, and this was inhibited by dexamethasone. Similarly, IL-17 increased the level of other fibroblast-derived inflammatory mediators, such as the alpha-chemokines, IL-8, and growth-related oncogene-alpha.

CONCLUSION

Our results, which demonstrate for the first time that eosinophils are a potential source of IL-17 within asthmatic airways, suggest that IL-17 might have the potential to amplify inflammatory responses through the release of proinflammatory mediators such as alpha-chemokines.

Bud8p and Bud9p, proteins that may mark the sites for bipolar budding in yeast

The bipolar budding pattern of a/alpha Saccharomyces cerevisiae cells appears to depend on persistent spatial markers in the cell cortex at the two poles of the cell. Previous analysis of mutants with specific defects in bipolar budding identified BUD8 and BUD9 as potentially encoding components of the markers at the poles distal and proximal to the birth scar, respectively. Further genetic analysis reported here supports this hypothesis. Mutants deleted for BUD8 or BUD9 grow normally but bud exclusively from the proximal and distal poles, respectively, and the double-mutant phenotype suggests that the bipolar budding pathway has been totally disabled. Moreover, overexpression of these genes can cause either an increased bias for budding at the distal (BUD8) or proximal (BUD9) pole or a randomization of bud position, depending on the level of expression. The structures and localizations of Bud8p and Bud9p are also consistent with their postulated roles as cortical markers. Both proteins appear to be integral membrane proteins of the plasma membrane, and they have very similar overall structures, with long N-terminal domains that are both N- and O-glycosylated followed by a pair of putative transmembrane domains surrounding a short hydrophilic domain that is presumably cytoplasmic. The putative transmembrane and cytoplasmic domains of the two proteins are very similar in sequence. When Bud8p and Bud9p were localized by immunofluorescence and tagging with GFP, each protein was found predominantly in the expected location, with Bud8p at presumptive bud sites, bud tips, and the distal poles of daughter cells and Bud9p at the necks of large-budded cells and the proximal poles of daughter cells. Bud8p localized approximately normally in several mutants in which daughter cells are competent to form their first buds at the distal pole, but it was not detected in a bni1 mutant, in which such distal-pole budding is lost. Surprisingly, Bud8p localization to the presumptive bud site and bud tip also depends on actin but is independent of the septins.

Bronchial mucosa produced by tissue engineering: a new tool to study cellular interactions in asthma

BACKGROUND

The use of fiberoptic bronchial biopsies has improved our understanding of the immunopathology of asthma. However, this approach offers a limited ability to perform mechanistic studies observing cell-cell and cell-matrix interactions, which are a key issue in the study of airway remodeling. Tissue engineering is a technique that combines the use of biology and engineering expertise to generate a limitless amount of tissue from small samples. This technology allows for the study of cell interactions under conditions as close as possible to the natural environment.

OBJECTIVE

The aim of this study was to evaluate the feasibility of an engineered human bronchial mucosa as a model to study cellular interactions in asthma.

METHODS

Human bronchial fibroblasts from normal and asthmatic donors were incorporated into collagen gel. Bronchial epithelial cells were seeded over this gel and then cultured in an air-liquid interface in the presence or the absence of T lymphocytes. Biopsy specimens from these engineered mucosa were taken for structural and ultrastructural analysis, and T lymphocytes were harvested and used to localize IL-5.

RESULTS

Histologic analysis showed that engineered mucosa with normal bronchial cells presented a pseudostratified ciliated epithelium with the presence of mucus secretory cells. The electron microscopy analysis confirmed these histologic results. These features were comparable with those observed in normal bronchial tissues. However, in engineered mucosa from asthmatic subjects, the tissue structure was disorganized, particularly the epithelial cell arrangement. The percentage of IL-5(+) lymphocytes was significantly (P =.03) higher in engineered bronchial mucosa from asthmatic subjects (87% +/- 2%) compared with mucosa from normal volunteers (2% +/- 0.3%).

CONCLUSION

Using tissue engineering, we produced an in vitro model of bronchial mucosa from normal and asthmatic subjects. These models could be a valuable tool to better understand key mechanisms involved in inflammation and airway repair.

Observations on topical ivermectin in the treatment of otoacariosis, cheyletiellosis, and toxocariosis in cats

The purpose of this study was to observe the efficacy of a topical pour-on formulation of ivermectin in the treatment of otoacariosis, cheyletiellosis, and toxocariosis in cats. Forty-five cats were treated. All cats received 2 to 4 topical applications of ivermectin on the skin between the shoulder blades in a narrow strip, 14 days apart. This practical treatment was effective in 96% (23/24) of cases of feline otoacariosis and in 100% (20/20) of cats with toxocariosis. All cats with cheyletiellosis (16/16) received 4 treatments and had resolution of clinical signs, but one Cheyletiella egg could still be found 45 days after the last treatment. The viability of this egg could not be evaluated, but the cats were still free of clinical signs on follow-up 6 months later. The treatment was well tolerated in all the animals. A few cats developed a transient small alopecic area and mild scaling at the site of application of the drug.

Topical (pour-on) ivermectin in the treatment of canine scabies

The efficacy of a pour-on formulation of ivermectin at 500 micrograms/kg body weight applied on the dorsum on days 1 and 15 was evaluated in 90 dogs from a shelter, naturally infested with Sarcoptes scabiei. This very practical form of treatment was successful in eradicating scabies from this shelter.

Serum free thyroxine concentrations measured by chemiluminescence in hyperthyroid and euthyroid cats

Serum free thyroxine (FT4) concentrations using chemiluminescence were measured in hyperthyroid cats (n = 72) and clinically normal cats (n = 129) to establish reference values and to determine if this method could be a useful alternative to total T4 (TT4) measurement by radioimmunoassay (RIA). Mean serum FT4 concentration (68.3 +/- 26.8 pmol/L) of hyperthyroid cats was significantly higher than that of euthyroid cats (22.9 +/- 4.8 pmol/L). Reference values for basal FT4 of hyperthyroid and healthy cats were 33 to 114 pmol/L and 16 to 30 pmol/L, respectively. The results of the present study suggest that FT4 measured by chemiluminescence could be a useful alternative to TT4 measured by RIA when evaluating thyroid function in cats, since the hazardous effects of radioactive materials on the manipulators and the environment could be avoided. Further studies are required to corroborate these preliminary findings.

Expression of human glucocorticoid receptor gene and interaction of nuclear proteins with the transcriptional control element

We have identified sequences responsible for the expression of the human glucocorticoid receptor gene (GR gene) using a set of 5' promoter deletion mutants in HeLa, human placenta, and human breast tumor (MCF-7) cells. The chimeric gene construct -892 5'-GAAGTGACACACTTC3' -878-CAT was sufficient for high level of expression in HeLa and placenta cells in culture. Deletion of palindromic sequences decreased levels of GR expression in these cells. By oligonucleotide-affinity chromatography with the palindromic glucocorticoid receptor enhancing factor-binding element (GREFE), we have isolated from human placenta nuclear extract two novel proteins glucocorticoid receptor enhancing factors 1 and 2 (GREF1 and GREF2), with apparent molecular masses of 80 and 62 kDa, respectively. These proteins, similar to the DNA-binding autoantigen Ku are, like Ku, heterodimers of polypeptide subunits p80 and p62, immunologically related to factors binding to proximal sequence element 1 in the promoter of small nuclear RNA (PSE1) and transferrin receptor enhancing factors. Both Ku80 and Ku70 polypeptides were present in high concentrations in human placenta and HeLa cells. In MCF-7 cells, however, only a high level of p62 was detected. While cotransfection of pcDNA-Ku80 with pHGR(-892 to -878)-CAT potentiated the expression of CAT, introduction of pcDNA-Ku70 did not affect the expression of CAT in transfected MCF-7 cells. UV cross-linking analysis showed that only GREF1 contacted DNA directly. Supershift assays with monoclonal antibodies Ab 111 (Ku80) or Ab N3H10 (Ku70) showed a direct interaction of GREF1 and GREF2 heterodimers with the palindrome. Partial peptide fingerprinting of GREF1 and GREF2 using alpha-chymotrypsin and immunoblotting with Ab 111 and Ab N3H10 confirmed their identities as Ku80 and Ku70, respectively.

Increased xylanase yield in Streptomyces lividans: dependence on number of ribosome-binding sites

The Streptomyces lividans xylanase A (XlnA) signal peptide (sp) was replaced with the signal peptides of either mannanase A (ManA) or cellulase A (CelA), two enzymes secreted by S. lividans. Depending on the location of the ribosome binding sites (RBS) with respect to a potential initiation codon, the length of the putative sps of ManA and CelA is either 34 or 43 amino acids and 27 or 46 amino acids, respectively. The sequence encoding these sps were fused to the xylanase A gene (xlnA). Clones harboring the short sps of ManA and CelA produced as much xylanase as the clone with the control wild-type sp sequence of XlnA. In clones containing the long sps of ManA and CelA, the XlnA production was enhanced 1.5- and 2.5-fold, respectively. These XlnA yields are reduced by half and one third respectively when the internal initiation codons of the long sp sequences of ManA and CelA are mutated. Since these clones exhibited the same transcription levels, the results indicate that both RBSs are used concomitantly in S. lividans to increase the enzyme production at the translational level. However, when the short and long sps of ManA were fused to the long CelA sp sequence, giving constructs containing respectively 3 and 4 RBSs, a decrease in xylanase production was observed.

Serum-free thyroxine concentrations, measured by chemiluminescence assay before and after thyrotropin administration in healthy dogs, hypothyroid dogs, and euthyroid dogs with dermathopathies

The purpose of this study was to determine the usefulness of free thyroxine (FT4) measured by chemiluminescence in evaluating thyroid function in dogs. Total thyroxine (TT4) concentration measured by radioimmunoassay (RIA) and FT4 measured by chemiluminescence were evaluated in 30 healthy dogs, 60 euthyroid dogs with concurrent dermatopathies, and 30 hypothyroid dogs before and after intravenous stimulation with 1 or 2 IU of thyrotropin (TSH). Median basal TT4 and median TT4 concentrations at 4 h post-TSH administration were not significantly different (P < 0.0001) between healthy dogs and euthyroid dogs with dermatopathies, but were significantly higher than those in hypothyroid dogs. In healthy dogs, the median TT4 concentrations at 4 and 6 h post-TSH administration were not significantly different. Median basal FT4 and median FT4 concentrations at 4 h post-TSH administration in healthy dogs were significantly lower (P < 0.0001) than those in euthyroid dogs with dermatopathies, but significantly higher than the same parameters in hypothyroid dogs. There was a significant difference between the median FT4 concentrations at 4 h post-TSH administration and median basal FT4 concentrations for healthy dogs and euthyroid dogs with dermatopathies, but not for hypothyroid dogs. Lastly, in healthy dogs, median FT4 concentrations at 4 and 6 h post-TSH administration were not significantly different. Free thyroxine measured by chemiluminescence was highly correlated (P < 0.0001; Spearman r = 0.91) with FT4 measured by the reference method for free hormone analysis, namely, equilibrium dialysis, when sera from 56 dogs were used.

Effect of signal peptide alterations and replacement on export of xylanase A in Streptomyces lividans

Starting from its translation initiation site, the Streptomyces lividans xylanase A signal peptide consists of 41 amino acids. This signal peptide was deleted and successively replaced with one of six signal peptides from other enzymes secreted by S. lividans and by a signal peptide from the outer membrane protein (LamB) of Escherichia coli. Deletion of the xylanase A signal peptide or modification of its cleavage site abolished secretion of the enzyme. Replacement with the signal peptides of either xylanase B, cellulase A, mannanase, or acetylxylan esterase produced equivalent amounts of xylanase A, while the signal peptides of cellulase B, xylanase C, and LamB secreted less enzyme than did the wild type. All the clones exhibited the same transcription levels, which indicated that the variations in xylanase production were due to the natures of the signal sequences.

Substitution of Cys-560 by Phe, Trp, Tyr, and Ser in the first zinc finger of human androgen receptor affects hormonal sensitivity and transcriptional activation

We have established and characterized four human androgen receptor (AR) mutants, AR C560F, C560W, C560Y, C560S). To assess the functional significance of these substitutions, we compared the transcriptional activation, hormone binding affinity, receptor-DNA interaction, and the subcellular distribution of the hormone-receptor complexes. Binding studies showed that all mutants bound methyltrienolone (R1881) with wild type affinity (Kd = 0.5 nM). Transactivation efficiency, as compared to wild type AR, increased 150% with C560F and decreased to 70% with C560W and C560Y and to 40% with mutant C560S. Subcellular receptor distribution showed that 85% of C560F bound with hormone was extracted from the nuclear fraction and 15% in the cytosol. Gel mobility shift assays showed that C560F expressed in CV-1 cells bound to an androgen responsive element (ARE) with equal efficiency as the wild type human AR. The mutants C560W and C560Y demonstrated a lower ability to bind to ARE, whereas C560S showed a significantly lower ability to interact with ARE. We propose that the change in polarity introduced into the loop structure by C560S leads to a shorter period of contact between the mutant receptor and DNA resulting in decreased transcriptional activation levels.

Transcription activation of mouse mammary tumor virus-chloramphenicol acetyltransferase: a model to study the metabolism of cortisol

The human 11 beta-hydroxysteroid dehydrogenase (h11 beta-HSD) inactivates the active corticosteroid cortisol to its inactive metabolite cortisone. We have developed transactivation analyses of the reporter chimeric gene mouse mammary tumor virus-chloramphenicol acetyltransferase (MMTV-CAT) to study the catalytic activity of h11 beta-HSD introduced by cotransfection into receptor and 11 beta-HSD deficient CV-1 cells. Assay of 11 beta-HSD expressed in CV-1 cells by cotransfection showed that the catalyzed dehydrogenation of cortisol to cortisone was 2-fold higher in the presence of NADP. The reductase activity was dependent on the coenzyme NADPH. The addition of increasing concentrations of the inhibitor carbenoxolone (CBX) in the incubates blocked the enzyme activity in a dose dependent fashion. In CV-1 cells cotransfected with expression vectors of either human glucocorticoid (hGR1-777) or mineralocorticoid (hMR1-984) and the reporter plasmid MMTV-CAT, dexamethasone (DEX), aldosterone (ALDO), cortisol, and corticosterone induction of CAT activity was dose dependent. Cotransfection of CV-1 cells transfected with 10 micrograms of 11 beta-HSD expression vector reduced the transactivation of MMTV-CAT by hGR or hMR in the presence of either cortisol or corticosterone to basal values. The concomitant addition of 100 nM cortisone and 1 microM NADPH to these transfectants elevated CAT activity. These data show that transactivation analyses can be used to study the 11 beta-HSD-catalyzed regulation of corticosteroid levels, which triggers physiological processes and in certain cases provides an alternative to animal experimentation.

11 beta-hydroxysteroid dehydrogenase activity in human lung cells and transcription regulation by glucocorticoids

Selectivity to aldosterone (Aldo) in mineralocorticoid target tissues has been suggested to be due to the activity of 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD). This enzyme inactivates the endogenous glucocorticoid cortisol, thus permitting the unhindered access of Aldo to the mineralocorticoid receptor. The 11 beta-HSD activity was measured by the conversion of cortisol to cortisone and vice versa. Concomitant treatment of the cells with either cortisone or cortisol in the presence of the glycyrrhetinic acid derivative carbenoxolone (CBX) blocked both activities of 11 beta-HSD. Dexamethasone and Aldo activated the transcription of transiently transfected mouse mammary tumor virus-bacterial chloramphenicol acetyltransferase chimeric gene in LU-19 cells. The transcription activation by cortisol was synergized by concomitant treatment of the transfectants with CBX. Transactivation with Aldo was inhibited by spironolactone. The enzyme 11 beta-HSD in LU-19 cells is similar to the cloned liver isoform and catalyzes both reduction and dehydrogenation.

11 beta-Hydroxysteroid dehydrogenase and tissue specificity of androgen action in human prostate cancer cell LNCaP

Incubation of whole LNCaP cells in suspension with tritium labeled cortisol revealed two major and one minor radioactive product. Of the major products, one migrated with an Rf value identical to cortisol (Kendall's compound "F"), and the second migrated with an Rf value similar to nonradioactive cortisone (Kendall's compound "E"); the third minor product comigrated with 21-acetylated cortisol. The conversion of cortisol to cortisone was linear with respect to cell number, and conversion reached a plateau after 120 min of incubation at 37 degrees C. One half of the cortisol was converted to cortisone within 2 h of incubation at 37 degrees C. This conversion was nicotine amide dinucleotide (NAD) dependent. Low levels of transcription activation by cortisol were documented in LNCaP cells transfected with glucocorticoid and androgen responsive mouse mammary tumor virus-bacterial chloramphenicol acetyltransferase chimeric gene (MMTV-CAT). Hormone binding assay and transactivation analysis revealed the presence of a functional mineralocorticoid receptor in LNCaP cells. Treatment of transfectants with F in the presence of carbenoxolone, a potent inhibitor of 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD), resulted in a two orders of magnitude increase in measurable CAT activity. The addition of the reduced form of nicotine amide dinucleotide (NADH) in the presence of 10(-7) M E stimulated measurable CAT activity in LNCaP cells. In conferring aldosterone specificity in mineralocorticoid target tissues, 11 beta-HSD may have an important role as "gate keeper" in allowing a specific androgen response in hormone responsive LNCaP prostate cancer cells.

Antiandrogens inhibit human androgen receptor-dependent gene transcription activation in the human prostate cancer cells LNCaP

Human androgen receptor (hAR) is a ligand-dependent transcription factor that mediates androgen-induced actions on target tissues. Transfection studies in the human prostate cancer cell line LNCaP examine the ability of dihydrotestosterone (DHT), hydroxyflutamide (HO-FLU), cyproterone acetate (Cypro.A), and RU 23908-10 to stimulate or to inhibit the transcription activation of mouse mammary tumor virus-bacterial chloramphenicol acetyltransferase (MMTV-CAT). DHT stimulated transcription activation of MMTV-CAT gene in LNCaP cells in a dose-dependent manner. HO-FLU, Cypro.A, and RU 23908-10, though only partially, also stimulated the transcription activation of MMTV-CAT. Despite this, 100- to 1,000-fold molar excess of all antiandrogens inhibited the agonistic activity of 10 nM DHT in this system. Receptor binding assays confirmed that HO-FLU, Cypro.A, and RU 23908-10 competed with DHT for AR binding in LNCaP cells. Western blot analysis using AR antipeptide antibodies raised in rabbits revealed the presence of two AR protein bands in LNCaP cells, following treatment with antiandrogens. Increasing doses of HO-FLU stimulated the expression of the 114-kDa AR by 2.5-fold, but did not affect the 108-kDa AR. Increasing doses of Cypro.A and RU 23908-10 decreased the levels of both the 114-kDa and the 108-kDa AR. Although the exact nature of 108-kDa and 114-kDa AR in LNCaP cells is still unknown, these data suggest that the regulatory actions of each individual antiandrogen on AR expression in LNCaP cells may be different.

Interaction of antiandrogen-androgen receptor complexes with DNA and transcription activation

Human androgen receptor (hAR) is a ligand-dependent transcription factor that mediates androgen-induced actions on target tissues. Transfection studies in receptor deficient monkey kidney cells CV-1 in culture examine the ability of dihydrotestosterone (DHT) and of the antiandrogens hydroxylflutamide (HO-FLU), cyproterone acetate (Cypro.A) and RU 23908-10 to stimulate or to inhibit the transcription activation of mouse mammary tumor virus-bacterial chloramphenicol acetyltransferase (MMTV-CAT). CV-1 cells cotransfected with wild type hAR (hAR1-910) and MMTV-CAT, were treated with varying concentrations of DHT. DHT stimulated transcription activation of MMTV-CAT gene in a dose-dependent fashion. Cypro.A though only partially, also stimulated the transcription activation of MMTV-CAT. In the absence of steroids, HO-FLU induced the MMTV-CAT transcription in transfectants only 4% above the basal level. RU 23908-10 revealed the least agonistic activity at concentrations between 10 nM and 1 microM. Despite this, 100- to 1000-fold molar excess of all antiandrogens inhibited the agonistic activity of 10 nM DHT in this system. Receptor binding assays confirmed that HO-FLU, Cypro.A and RU 23908-10 competed with [3H]DHT for AR binding with hAR expressed in CV-1 cells. Western blot analysis using AR antipeptide antibodies raised in rabbits revealed the presence of two AR protein bands in extracts prepared from hAR1-910 transfected CV-1 cells. Incubation of labeled synthetic palindromic androgen responsive element (ARE) with the hAR containing CV-1 cell extracts followed by u.v. cross-linking demonstrated the specificity of AR-DNA interaction. Analysis by gel mobility shift assays showed that the interaction of AR-antiandrogen complexes with labeled ARE was specific.