Histamine H1-receptor antagonists inhibit nuclear factor-kappaB and activator protein-1 activities via H1-receptor-dependent and -independent mechanisms.

BACKGROUND: Histamine H1-receptor antagonists are used to relieve the symptoms of an immediate allergic reaction. They have additional anti-inflammatory effects that could result from an inhibition of the transcription factors activator protein-1 (AP-1) and nuclear factor-kappa B (NF-kappaB). The implication of the H1-receptor in these effects is controversial. Diphenhydramine is a first-generation H1-receptor antagonist while mizolastine and desloratadine are second-generation compounds. Mizolastine is also an inhibitor of 5-lipoxygenase (5-LO), an enzyme that has been involved in NF-kappaB activation. OBJECTIVE: We measured the ability of antihistamines to reverse histamine-induced smooth muscle contraction, an effect that involves the H1-receptor. We then investigated whether these drugs affect NF-kappaB and AP-1 activities in A549 lung epithelial cells, and whether this potential regulation involves H1-receptor and 5-LO. METHODS: Muscle tone was measured on tracheal segments of guinea-pigs. The H1-receptor was overexpressed by transfection and detected by Western blotting and immunofluorescence microscopy. NF-kappaB and AP-1 activities were assessed by reporter gene assays in cells overexpressing or not overexpressing the H1-receptor. Production of regulated upon activation, normal T cell expressed andsecreted (RANTES), a chemokine whose expression is induced through NF-kappaB, was measured using an immunoassay. RESULTS: H1-receptor antagonists reversed histamine-induced contraction in a dose-dependent manner. Induction of AP-1 and NF-kappaB activities by histamine and the down-regulatory effect of antihistamines required overexpression of the H1-receptor. In contrast, when tumour necrosis factor-alpha and a phorbol ester were used to stimulate NF-kappaB and AP-1 activities, respectively, repression of these activities did not involve the H1-receptor. Indeed, repression was triggered only by a subset of H1-receptor antagonists and was not stronger after overexpression of the H1-receptor. Mizolastine and desloratadine dose-dependently decreased tumour necrosis factor-alpha-induced production of RANTES. Diphenhydramine, H2- and H3-receptor antagonists as well as selective inhibitors of 5-LO were ineffective in this assay. CONCLUSION: Repression of NF-kappaB and AP-1 activities by H1-receptor antagonists involves H1-receptor-dependent and -independent mechanisms but not 5-LO.

IL-10 promoter and IL4-Ralpha gene SNPs are associated with immediate beta-lactam allergy in atopic women.

BACKGROUND: Allergic reactions to beta-lactam antibiotics represent the most frequent cause of immunological drug reactions. OBJECTIVE: This study evaluates the involvement of genetic susceptibility factors in patients with immediate allergic reactions to beta-lactams. We examined 15 single nucleotide polymorphisms (SNP) of genes coding proteins implicated in immunoglobulin (Ig)E synthesis regulation. METHODS: We performed a case-control study involving 44 patients with immediate beta-lactam allergy and 44 control subjects, all matched for sex and atopy. Interleukin (IL)-4, IL-13, IL-4Ralpha, signal transducer and activator of transcription 6 (STAT6), interferon (IFN)-gammaR1, IFN-gammaR2 and FcepsilonRIbeta gene polymorphisms were determined using polymerase chain reaction (PCR) restriction fragment length polymorphism, and IL-21R gene and IL-10 promoter polymorphisms by direct sequencing. RESULTS: Our analysis did not reveal differences in the distribution of the 15 SNPs between allergic patients and controls. However, among atopic subjects, we found two distinct significant associations between immediate beta-lactam allergy in women and the Ile75Val variant of IL-4Ralpha gene (P = 0.012, OR = 5.4, CI: 1.16-27.7), and two linked IL-10 promoter gene polymorphisms, -819C>T and -592 C>A (P = 0.023, OR = 17.5, CI: 1.26-533.07). In contrast, we observed no association in allergic male subjects in the atopic population. Interestingly, the IL-4Ralpha Ile75Val variant could have a paradoxal protective effect in atopic male patients (P = 0.004, OR = 0.07, CI: 0.01-0.66). CONCLUSION: Our findings suggest that polymorphisms in the IL-10 promoter and IL-4Ralpha genes are genetic factors that favour beta-lactam immediate allergies in female patients with atopy.

[Glucocorticoids and their receptor: mechanisms of action and clinical implications]. / Les glucocorticoïdes et leur récepteur: mécanismes d'action et conséquences cliniques.

BACKGROUND: Glucocorticoids are used as anti-inflammatory, immuno-modulatory, anti-proliferative and cytotoxic drugs, but they also trigger important side-effects. These hormones bind to glucocorticoid receptor alpha (GRalpha), an intracellular protein, which acts essentially in the nucleus. MAIN POINTS: GRalpha is a ligand-activated transcription factor that positively or negatively regulates gene expression by distinct mechanisms. Stimulation of gene transcription occurs after direct binding of the receptor to specific responsive DNA elements. Gene activation by glucocorticoids is mainly responsible for certain adverse effects. In contrast, the therapeutic effects of glucocorticoids are predominantly mediated through repression of genes encoding inflammatory mediators. Inhibitory protein-protein interaction between the hormone-activated receptor and the transcription factors NF-kappaB and AP-1 was found to be the underlying mechanism. However, inhibition of other transcription factors may account for deleterious effects of glucocorticoids, such as adrenal suppression and osteoporosis. GRalpha also mediates rapid non-genomic effects of glucocorticoids. Side-effects are reduced by using topical glucocorticoids which have a low systemic bioavailability. Moreover, it is important to determine the lowest effective maintenance dose of systemic and topical glucocorticoids to further decrease the risk of adverse effects. This is particularly justified because inhibition of AP-1 and NF-kappaB activities, that is the anti-inflammatory effect, occurs at much lower hormone concentrations than transactivation. PERSPECTIVES: Clinical use of glucocorticoids is limited by occurrence of severe adverse effects. Therefore, the current aim is to design GRalpha ligands that retain only the anti-inflammatory activities of GC.

Correlation between different gene expression assays designed to measure trans-activation potencies of systemic glucocorticoids.

The glucocorticoids (GC) betamethasone, dexamethasone, hydrocortisone, methylprednisolone, prednisolone and triamcinolone acetonide are currently used in the treatment of inflammatory diseases. Through a process called trans-activation, GC activate gene expression and produce various physiological and pharmacological effects. In particular, by inducing gluconeogenic enzymes, long-term GC treatment may cause diabetes. Using three different assays, we have extensively compared the capacity of the above GC to activate gene expression. trans-Activation of a GC inducible luciferase gene was assessed in HeLa and A549 cells after stable and transient transfection, respectively. In hepatoma tissue culture cells, we measured trans-activation of the endogenous gene encoding tyrosine aminotransferase, a gluconeogenic enzyme. Half-maximal effective concentrations of GC were determined by dose-response analyses. Results obtained with these assays were highly correlated and GC were ranked in three groups according to their trans-activation potency: betamethasone, dexamethasone, and triamcinolone acetonide > methylprednisolone and prednisolone > hydrocortisone. Potencies were not strictly related to receptor binding affinities and not significantly affected by the amount of endogenous GC receptor.

Transcriptional potencies of inhaled glucocorticoids.

Glucocorticoids (GC) are the most effective anti-inflammatory drugs used in asthma. By a process called trans-activation, they increase the transcription of genes involved in either beneficial processes or certain side effects. Through trans-repression, they inhibit the transcription factors nuclear factor kappa B (NF-kappaB) and activator protein-1 (AP-1), thereby decreasing the expression of many genes encoding inflammatory mediators such as the cytokine RANTES. We have measured the trans-activation and trans-repression potencies of the five currently available inhaled GC using reporter gene assays. The rank order of trans-activation potencies in HeLa cells stably transfected with a GC-inducible luciferase gene was fluticasone propionate > budesonide and triamcinolone acetonide > beclomethasone dipropionate and flunisolide. For all GC except beclomethasone dipropionate, there was a highly significant correlation between their potency to trans-activate in HeLa cells and their capacity to induce the gluconeogenic enzyme tyrosine aminotransferase in hepatoma tissue culture (HTC) cells. The rank order of trans-repression potencies in A549 lung cells transiently transfected with an AP-1- or NF-kappaB-dependent luciferase gene was fluticasone propionate > budesonide > beclomethasone dipropionate, triamcinolone acetonide, and flunisolide. The same rank order was found for inhibition of RANTES release. Thus, determination of trans-repression and trans-activation potencies of GC may help to predict their capacity to produce anti-inflammatory and side effects, respectively.

VEGF levels in asthmatic airways do not correlate with plasma extravasation.

BACKGROUND: Vascular permeability/vascular endothelial growth factor (VEGF) is a multifunctional cytokine which plays a role in chronic inflammation and angiogenesis. Its expression in bronchoalveolar lavage (BAL) has not been determined although VEGF may be relevant to the pathophysiology of asthma in which oedema is an important feature. METHODS: We studied VEGF, albumin and IgA immunoreactive levels in the BAL fluids obtained from 27 chronic stable asthmatics, nine untreated chronic bronchitis patients and 15 control subjects. RESULTS: BAL fluid levels of VEGF and VEGF normalized to IgA were not significantly different in any patient group. Both asthmatic steroid- and non-steroid-treated groups had significantly lower albumin levels in their BAL fluids explaining most of the 179% increased VEGF normalized to albumin ratios in non-steroid treated asthmatics. Moreover, VEGF and albumin markers correlated in control subjects (r = 0.73, P = 0.006) and in chronic bronchitics (r = 0.75, P = 0.03, Spearman test), but not in asthmatics. VEGF was inversely correlated with asthma severity (GINA/NHLBI scores) in non-steroid treated asthmatics (tau = - 0.52, P = 0.009, Kendall test). CONCLUSIONS: Thus, the potential role of VEGF in asthma requires further studies on bronchial biopsies and induced sputum.

The glucocorticoid receptor gene as a candidate for gene therapy in asthma.

Glucocorticoids (GC) are commonly used as anti-inflammatory drugs in asthma, but can produce serious secondary effects and, moreover, be inefficient in corticoresistant asthmatics. After binding to the glucocorticoid receptor (GR), they repress the synthesis of proinflammatory cytokines via inhibition of the transcription factors AP-1 and NF-kappa B. Since qualitative and quantitative defects of the GR have been reported in corticoresistant patients, the transfer of the GR gene in the lung epithelium, the primary site of inflammation in asthma, may restore sensitivity to GC in these patients. As a prerequisite to in vivo studies, we have transfected A549 human lung epithelial cells with a GR expression vector. Using AP-1 and NF-kappa B-dependent reporter gene assays and an immunoassay for the pro-inflammatory cytokine RANTES, we show that the over-expressed GR significantly repressed AP-1 and NF-kappa B activities in the absence of hormone and that the GC dexamethasone produced an additive inhibitory effect. The GC-independent repression of AP-1 and NF-kappa B activities was further demonstrated by overexpressing a ligand-binding deficient GR mutant. Our data suggest that delivery of the GR gene in vivo may reduce inflammation without recourse to GC and may constitute an alternative therapeutic approach for corticoresistant asthma.

Rifampicin is not an activator of the glucocorticoid receptor in A549 human alveolar cells.

It has recently been reported that rifampicin activates the glucocorticoid receptor and acts as an immunosuppressive drug. Because rifampicin constitutes an essential part of pulmonary tuberculosis therapy, we have examined whether it triggers glucocorticoid-like effects in alveolar cells. We have used reporter gene assays to measure the trans-activating and trans-repressing capacity of the glucocorticoid receptor after treating A549 human alveolar cells with rifampicin. The data show that rifampicin neither activated transcription from a promoter containing a glucocorticoid response element nor repressed the activity of activator protein 1 and nuclear factor kappaB, which are transcription factors involved in the immune response. In addition, rifampicin was also unable to inhibit the expression of an endogenous gene that contains activator protein 1 and nuclear factor kappaB response elements and encodes the proinflammatory cytokine RANTES (regulated upon activation normal T expressed and secreted protein). Finally, nuclear translocation of the glucocorticoid receptor, which occurs after ligand binding, was not triggered by rifampicin. In contrast, the glucocorticoid dexamethasone scored positive in all corresponding control experiments. In conclusion, rifampicin is not an activator of the glucocorticoid receptor in A549 alveolar cells. Our results support the clinical observation that rifampicin is not an immunosuppressive drug and suggest that the current medical practice concerning this antibiotic should not be changed.

Increased expression of tissue inhibitor of metalloproteinase-1 and loss of correlation with matrix metalloproteinase-9 by macrophages in asthma.

Alveolar macrophages (AMs) can mediate tissue destruction and repair by synthesizing matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) as well as inflammatory cytokines, which regulate their production. Imbalances between these enzymes and inhibitors may contribute to the tissue damage and remodeling seen in inflammatory diseases. In this study, we examined the role of AMs in chronic asthma. We have previously demonstrated an increased production of MMP-9 by AMs in untreated asthmatic patients as compared with healthy subjects, and in asthmatics treated with inhaled corticosteroids and patients with chronic bronchitis. We now report on the expression of TIMP-1, the inhibitor of MMP-9, and compare the levels and the regulation by cytokines of both MMP-9 and TIMP-1. Enzyme and inhibitor were measured using an enzyme immunoassay and immunoprecipitation. TIMP-1 steady-state mRNA levels were measured using the RNase protection assay. AMs from untreated asthmatics were found to produce more TIMP-1 both at protein and mRNA levels than AMs from other groups. The release of TIMP-1 and MMP-9 from individual AMs was significantly correlated in control populations and the molecules mainly complexed to each other, whereas this was not true for untreated asthmatics, indicating an imbalance between MMP-9 and TIMP-1 production. In the latter population, TIMP-1 release was inhibited by an anti-IL-6 antibody and MMP-9 release by anti-TNF-alpha, anti-IL-6, and anti-IL-1/beta antibodies. The imbalance of MMP-9 and TIMP-1 production, via the involvement of different cytokines, suggests that AMs may be involved in the abnormal repair observed in chronic asthma.

Gene transfer to human rheumatoid synovial tissue engrafted in SCID mice.

OBJECTIVE: To assess the feasibility of gene therapy in rheumatoid arthritis (RA) and determine the appropriate vector. METHODS: Human rheumatoid synovial tissue from 6 patients with RA was transduced ex vivo with a recombinant retroviral vector (pMFG.nlsLacZ) containing the Escherichia coli beta-galactosidase (beta-gal) gene in a coculture assay in the presence of 20 ng/ml tumor necrosis factor alpha (TNF-alpha) for promoting cell division. We also conducted in vitro infection experiments using an adenoviral vector (AdCMVSpl.LacZ) containing the beta-gal gene. After gene transduction, the synovial tissue was engrafted subcutaneously in 8-week-old severe combined immunodeficiency (SCID) CB17 mice. Beta-gal expression was then monitored as a function of time (up to 21 days) and of virus dose [up to 50 colony forming units (cfu)/cell]. The efficacy of direct in vivo gene transfer was also tested by injection of 10(6) cfu of pMFG.nlsLacZ into rheumatoid synovial tissue engrafted in SCID mice. RESULTS: When recombinant retroviral vector was used, 30 +/- 5% of ex vivo infected synovial cells were positive for staining. In synovial tissue implanted in SCID mice, beta-gal expression declined to 5% after one week, but persisted for at least 21 days. Direct injection of pMFG.nlsLacZ vector into the rheumatoid synovial tissue implanted in SCID mice allowed efficient and stable in vivo infection of the synovial tissue. Ex vivo gene transfer with adenoviral vector resulted in a 98% infection rate of the synovial lining cells. However, beta-gal activity declined 7 days after subcutaneous implantation. CONCLUSION: Highly efficient gene transfer in rheumatoid synovial tissue is achievable with both adenoviral and retroviral vectors, but the results were transient. Exogenous gene transfer through retroviral vectors required stimulation with TNF-alpha for synovial cell division and proviral integration. Direct in vivo gene transfer with recombinant retrovirus was shown to be efficient. Transduction of human synovial tissue engrafted in SCID mice is a potent tool for developing preclinical models of gene therapy in RA.

Improved performances of spot multiple peptide synthesis.

We have developed a new software for the design of peptides to be prepared by the manual Spot synthesis method. It covers most of the common protocols for epitope mapping and offers flexibility for planning the experiment. We have also quantified the coupling efficiencies of three different coupling methods for the synthesis of four model decapeptides. The DIC/HOBT procedure was superior (mean coupling yield per cycle: 87% to 91%) to methods using pentafluorophenyl esters of Fmoc amino acids. All four peptides prepared by the three different coupling protocols were reactive with their cognate monoclonal antibody. Finally, using the best coupling method, we synthesized peptides of increasing length (10 to 29 residues) bearing the model epitope AcPGK at the N terminus and showed that peptides of up to 29 residues were immunoreactive.