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Biomedical subjects

G Hofman

Publications and source records attributed to G Hofman.

16 recordsLinked to original sources
PubMed1999

Effect of interleukin-16-blocking peptide on parameters of allergic asthma in a murine model.

In this study, we examined whether peptides based on the hydrophilic Cluster of Differentiation (CD) 4-binding part of the amino acid sequence of human interleukin-16 can block interleukin-16-induced chemotaxis of murine lymphocytes in vitro. Peptide 3 was capable of inhibiting interleukin-16-induced chemotaxis of murine splenocytes in vitro. Next, we compared the effects of intra-airway administration of peptide 3 with those of antibodies to interleukin-16 on antigen-induced features in a murine model of allergic asthma. Intra-airway administration of peptide 3 largely inhibited the development of antigen-induced airway hyperresponsiveness while airway eosinophilia was not affected. Similar effects were observed after intranasal application of antibodies to interleukin-16. These results indicate that treatment with peptide 3 causes the same effects as do antibodies to interleukin-16, possibly via the inhibition of interaction between interleukin-16 and its receptor CD4. Therefore, peptide 3 could be useful as a lead compound in attempting to limit airway hyperresponsiveness via binding to CD4.

Administration, Intranasal↗
PubMed1999

Opposite effects of immunotherapy with ovalbumin and the immunodominant T-cell epitope on airway eosinophilia and hyperresponsiveness in a murine model of allergic asthma.

In the present study, we investigated immunotherapy using an entire protein or an immunodominant epitope in a murine model of allergic asthma. Immunotherapy was performed in ovalbumin (OVA)-sensitized mice before OVA challenge. Mice were treated subcutaneously with OVA, the immunodominant epitope OVA323-339, or vehicle. In vehicle-treated animals, repeated OVA challenge induced increased serum levels of OVA-specific immunoglobulin (Ig)G1, IgE, airway eosinophilia, and hyperresponsiveness, compared with saline-challenged animals. In addition, interleukin (IL)-4 and IL-5 production upon OVA restimulation of lung-draining lymph node cells in vitro were significantly increased in OVA-challenged animals. Immunotherapy using OVA significantly reduced airway eosinophilia and hyperresponsiveness. This finding was accompanied by significantly reduced OVA-specific IL-4 and IL-5 production. Further, OVA immunotherapy induced increased serum levels of OVA-specific IgG1, whereas OVA-specific IgG2a and IgE levels were not affected. In contrast to OVA immunotherapy, immunotherapy with OVA323-339 aggravated airway eosinophilia and hyperresponsiveness. OVA-specific IgG1, IgG2a, and IgE serum levels, and in vitro IL-4 and IL-5 production, were not affected. Thus, immunotherapy with protein resulted in beneficial effects on airway eosinophilia and hyperresponsiveness, which coincided with a local reduced T-helper 2 (Th2) response. In contrast, peptide immunotherapy aggravated airway hyperresponsiveness and eosinophilia, indicating a local enhanced Th2 response.

Animals↗
PubMed1998

Prevention of Th2-like cell responses by coadministration of IL-12 and IL-18 is associated with inhibition of antigen-induced airway hyperresponsiveness, eosinophilia, and serum IgE levels.

Allergic asthma is thought to be regulated by Th2 cells, and inhibiting this response is a promising mode of intervention. Many studies have focused on differentiation of Th cells to the Th1 or Th2 subset in vitro. IL-4 is essential for Th2 development, while IL-12 induces Th1 development, which can be enhanced by IL-18. In the present study, we investigated whether IL-12 and IL-18 were able to interfere in Th2 development and the associated airway symptoms in a mouse model of allergic asthma. Mice were sensitized with OVA using a protocol that induces IgE production. Repeated challenges by OVA inhalation induced elevated serum levels of IgE, airway hyperresponsiveness, and a predominantly eosinophilic infiltrate in the bronchoalveolar lavage concomitant with the appearance of Ag-specific Th2-like cells in lung tissue and lung-draining lymph nodes. Whereas treatments with neither IL-12 nor IL-18 during the challenge period were effective, combined treatment of IL-12 and IL-18 inhibited Ag-specific Th2-like cell development. This inhibition was associated with an absence of IgE up-regulation, airway hyperresponsiveness, and cellular infiltration in the lavage. These data show that, in vivo, the synergistic action of IL-12 and IL-18 is necessary to prevent Th2-like cell differentiation, and consequently inhibits the development of airway symptoms in a mouse model of allergic asthma.

Animals↗
PubMed1998

Involvement of IL-16 in the induction of airway hyper-responsiveness and up-regulation of IgE in a murine model of allergic asthma.

Experiments were designed to investigate the role of IL-16 in a mouse model of allergic asthma. OVA-sensitized mice were repeatedly exposed to OVA or saline aerosols. Bronchoalveolar lavage fluid (BALF) was collected after the last aerosol, and the presence of IL-16 was evaluated using a migration assay with human lymphocytes. Migration of lymphocytes was significantly increased in the presence of cell-free BALF from OVA-challenged mice compared with BALF from saline-challenged controls. This response was significantly inhibited after addition of antibodies to IL-16, demonstrating the presence of IL-16 in BALF of OVA-challenged animals. Immunohistochemistry was performed and revealed IL-16 immunoreactivity particularly in airway epithelial cells but also in cellular infiltrates in OVA-challenged mice. IL-16 immunoreactivity was absent in nonsensitized animals; however, some reactivity was detected in epithelial cells of sensitized but saline-challenged mice, suggesting that sensitization induced IL-16 expression in airway epithelium. Treatment of mice with antibodies to IL-16 during the challenge period significantly suppressed up-regulation of OVA-specific IgE in OVA-challenged animals. Furthermore, antibodies to IL-16 significantly inhibited the development of airway hyper-responsiveness after repeated OVA inhalations, whereas the number of eosinophils in bronchoalveolar lavage or airway tissue was not affected. In conclusion, IL-16 immunoreactivity is present in the airways after sensitization. After repeated OVA inhalation, IL-16 immunoreactivity is markedly increased and IL-16 is detectable in BALF. Furthermore, IL-16 plays an important role in airway hyper-responsiveness and up-regulation of IgE but is not important for eosinophil accumulation in a mouse model of allergic asthma.

Animals↗
PubMed1998

Modulation of airway hyperresponsiveness and eosinophilia by selective histamine and 5-HT receptor antagonists in a mouse model of allergic asthma.

1. Since both histamine and 5-hydroxytryptamine (5-HT) can be released by murine mast cells, we investigated the possible role of these autacoids on airway hyperresponsiveness (AHR), eosinophil infiltration and serum-IgE levels in a murine model of allergic asthma. 2. Ovalbumin-sensitized mice were exposed to either ovalbumin (2 mg ml(-1)) or saline aerosols on 8 consecutive days. Starting one day before the challenge, animals were injected i.p. twice a day with a 5-HT-type 1 (5-HT1) or type 2 (5-HT2) receptor antagonist (methiotepine, 1.25 or 2.0 mg kg(-1) and ketanserin, 12 mg kg(-1), respectively) or a histamine-type 1 (H1) or type 2 (H2) receptor antagonist (mepyramine, 12 or 20 mg kg(-1) and cimetidine, 10 or 25 mg kg(-1), respectively). Furthermore, animals were injected with a combination of cimetidine and ketanserin or with an alpha-adrenoceptor antagonist (phentolamine, 5 mg kg(-1)). 3. In vehicle-treated ovalbumin-challenged animals airway responsiveness to intravenous injections of methacholine in vivo was significantly (9 fold increase, P<0.01) increased when compared to vehicle-treated saline-challenged animals. Furthermore, ovalbumin challenge of vehicle-treated animals induced a significant increase in both eosinophil numbers in bronchoalveolar lavage (BAL) fluid (0+/-0, vehicle/saline and 15.0+/-5.9 x 10(4) cells vehicle/ovalbumin, P<0.05) and ovalbumin-specific IgE levels in serum (157+/-69 and 617+/-171 units ml(-1), respectively, P<0.05) compared to saline-challenged mice. Virtually no eosinophils could be detected in saline-challenged animals after all different treatments. 4. Treatment with ketanserin or cimetidine resulted in a partial but significant decrease of the ovalbumin-induced AHR compared to ovalbumin-challenged controls (P<0.05) and reduced eosinophil infiltration after ovalbumin challenge by 60% and 58%, respectively. The combination of cimetidine and ketanserin almost completely abolished AHR whereas eosinophilia was decreased by 49%. No effects of these antagonists were observed on IL-16 levels in BAL fluid or on serum antigen-specific IgE levels. Treatment with either the H1-receptor, the 5-HT1-receptor or the alpha-adrenoceptor antagonist, did not decrease the observed ovalbumin-induced airway responsiveness or eosinophilia in vehicle-treated animals. Higher doses of either methiotepine (2.0 mg kg(-1)) or mepyramine (20 mg kg(-1)) did decrease ovalbumin-induced eosinophil infiltration (by 67%, P<0.05 and 73%, respectively), whereas no effects of these antagonists were observed on ovalbumin-specific IgE levels in serum. 5. From these data it can be concluded that both histamine and 5-HT play a role in antigen-induced AHR and eosinophilia in the mouse.

Airway Resistance↗
PubMed1998

Allergen immunotherapy inhibits airway eosinophilia and hyperresponsiveness associated with decreased IL-4 production by lymphocytes in a murine model of allergic asthma.

In the present study, we investigated whether allergen immunotherapy is effective in a murine model with immunologic and pathophysiologic features reminiscent of allergic asthma. Ovalbumin-sensitized mice received increasing (1 microgram to 1 mg) subcutaneous doses of ovalbumin twice a week for 8 wk according to a semirush immunotherapy protocol as used in allergic patients. During immunotherapy, an initial rise in serum levels of ovalbumin-specific antibodies (immunoglobulin [Ig]G1, IgE, IgG2a) occurred, after which IgE levels decreased sharply concomitant with an increase in IgG2a levels. The increase in IgG2a levels, with the decline in IgE levels, suggests that during immunotherapy interferon-gamma production is increased or interleukin (IL)-4 production is decreased. After immunotherapy, inhalation challenge of the mice with ovalbumin revealed almost complete inhibition (98%, P < 0.01) of eosinophil infiltration into bronchoalveolar lavage and airway hyperresponsiveness (100% at 320 microgram/kg methacholine, P < 0.05) compared with sham-treated animals. In addition, IL-4 production of thoracic lymph node cells stimulated with ovalbumin in vitro was largely reduced (60%, P < 0.05) after immunotherapy. Thus, effective immunotherapy in this animal model appears to be due to modulation of antigen-specific T cells. Similar effects on airway symptoms and IL-4 production can be obtained within 1 wk by three injections of the highest dose of ovalbumin (1 mg). This animal model will be used as a preclinical model to improve allergen immunotherapy and to gain more insight into the mechanisms involved.

Alveolitis, Extrinsic Allergic↗
PubMed1998

Differential effects of endogenous and exogenous interferon-gamma on immunoglobulin E, cellular infiltration, and airway responsiveness in a murine model of allergic asthma.

The inflammatory response as seen in human allergic asthma is thought to be regulated by Th2 cells. It has been shown that interferon-gamma (IFN-gamma) can downregulate the proliferation of Th2 cells and therefore might be of therapeutic use. In the present study we have investigated the in vivo role of endogenous and exogenous IFN-gamma in a murine model with features reminiscent of human allergic asthma. IFN-gamma gene knockout (GKO) and wild-type mice were sensitized with ovalbumin and exposed to repeated ovalbumin aerosol challenges. In addition, wild-type mice were treated with intraperitoneal or nebulized recombinant murine IFN-gamma during the challenge period. Sensitized wild-type mice exhibited upregulated ovalbumin-specific IgE in serum, and airway hyperresponsiveness and infiltration of eosinophils and mononuclear cells in the bronchoalveolar lavage fluid (BALF) after ovalbumin challenge. In contrast, in GKO mice only reduced eosinophilic infiltration in the BALF was observed after ovalbumin challenge. In wild-type mice, parenteral IFN-gamma treatment downregulated ovalbumin-specific IgE levels in serum, and airway hyperresponsiveness and cellular infiltration in the BALF, whereas aerosolized IFN-gamma treatment only suppressed airway hyperresponsiveness. In vitro experiments showed that these effects of IFN-gamma appear not to be mediated via a direct effect on the cytokine production of antigen-specific Th2 cells. These data indicate that airway hyperresponsiveness can be downregulated by IFN-gamma locally in the airways, whereas for downregulation of IgE and cellular infiltration systemic IFN-gamma is needed. The present study shows that exogenous IFN-gamma can downregulate the allergic response via an antigen-specific T-cell independent mechanism, but at the same time endogenous IFN-gamma plays a role in an optimal response.

Administration, Inhalation↗
PubMed1997

Development of airway hyperresponsiveness is dependent on interferon-gamma and independent of eosinophil infiltration.

In this study the role of interleukin (IL)4, IL5, interferon (IFN) gamma, and tumor necrosis factor (TNF) alpha in the development of airway hyperresponsiveness and inflammatory cell infiltration was investigated using a murine model for allergic asthma. Mice were sensitized with ovalbumin and subsequently challenged repeatedly with ovalbumin aerosols. During the challenge period, mice were treated with monoclonal antibodies directed against IL4, IL5, IFN gamma, or TNF alpha. Control antibody-treated mice showed airway hyperresponsiveness to methacholine and the presence of eosinophils in bronchoalveolar lavage (BAL). Treatment with antibodies to IFN gamma completely abolished development of airway hyperresponsiveness in ovalbumin-challenged animals. After treatment with antibodies to TNF alpha, airway hyperresponsiveness in the ovalbumin-challenged animals was partially but not significantly inhibited. Antibodies to IL4 or IL5 did not inhibit airway hyperresponsiveness. The presence of eosinophils in BAL of ovalbumin-challenged mice was completely inhibited after treatment with antibodies to IL5. Treatment with antibodies to IL4, IFN gamma, or TNF alpha had no effect on eosinophilia. Because IFN gamma and IL5 have either an effect on the induction of airway hyperresponsiveness or on the development of eosinophil infiltration, our results suggest that the two phenomena are differentially regulated.

Administration, Inhalation↗
PubMed1996

Effect of dexamethasone and endogenous corticosterone on airway hyperresponsiveness and eosinophilia in the mouse.

1. Mice were sensitized by 7 intraperitoneal injections of ovalbumin without adjuvant (10 micrograms in 0.5 ml of sterile saline) on alternate days and after 3 weeks exposed to either ovalbumin (2 mg ml-1 in sterile saline) or saline aerosol for 5 min on 8 consecutive days. One day before the first challenge, animals were injected intraperitoneally on a daily basis with vehicle (0.25 ml sterile saline), dexamethasone (0.5 mg kg-1) or metyrapone (30 mg kg-1). 2. In vehicle-treated ovalbumin-sensitized animals ovalbumin challenge induced a significant increase of airway responsiveness to metacholine both in vitro (27%, P < 0.05) and in vivo (40%, P < 0.05) compared to saline-challenged mice. Virtually no eosinophils could be detected after saline challenge, whereas the numbers of eosinophils were significantly increased (P < 0.01) at both 3 and 24 h after the last ovalbumin challenge (5.48 +/- 3.8 x 10(3) and 9.13 +/- 1.7 x 10(3) cells, respectively). Furthermore, a significant increase in ovalbumin-specific immunoglobulin E level (583 +/- 103 units ml-1, P < 0.05) was observed after ovalbumin challenge compared to saline challenge (201 +/- 38 units ml-1). 3. Plasma corticosterone level was significantly reduced (-92%, P < 0.001) after treatment with metyrapone. Treatment with metyrapone significantly increased eosinophil infiltration (17.4 +/- 9.93 x 10(3) and 18.7 +/- 2.57 x 10(3) cells, P < 0.05 at 3 h and 24 h, respectively) and potentiated airway hyperresponsiveness to methacholine compared to vehicle-treated ovalbumin-challenged animals. Dexamethasone inhibited both in vitro and in vivo hyperresponsiveness as well as antigen-induced infiltration of eosinophils (0, P < 0.05 and 0.7 +/- 0.33 x 10(3) cells, P < 0.05 at 3 h and 24 h, respectively). Metyrapone as well as dexamethasone did not affect the increase in ovalbumin-specific immunoglobulin E levels after ovalbumin challenge (565 +/- 70 units/ml-1; P < 0.05; 552 +/- 48 units ml-1, P < 0.05 respectively). 4. From these data it can be concluded that exogenously applied corticosteroids can inhibit eosinophil infiltration as well as airway hyperresponsiveness. Vise versa, endogenously produced corticosteroids play a down-regulating role on the induction of both eosinophil infiltration and airway hyperresponsiveness.

Animals↗
PubMed1996

Role of interleukin-5 and substance P in development of airway hyperreactivity to histamine in guinea-pigs.

In this study, we examined the mechanism by which bronchoalveolar lavage (BAL) cells induced hyperreactivity of the trachea in vitro. As both interleukin-5 (IL-5) and substance P (SP) appeared to be involved, the effect of these mediators was examined in vivo. Tracheae were incubated with BAL cells from ovalbumin or saline challenged animals, and from naive animals, in the absence or presence of either IL-5, SP, or both. In addition, the effect of intra-airway application of IL-5, SP, both, or vehicle on tracheal hyperreactivity was examined. Incubation of tracheae with BAL cells from ovalbumin challenged animals induced an increase (30 +/- 10%) in the maximal response to histamine. The hyperreactivity could be completely inhibited by co-incubation with 5-lipoxygenase inhibitor, AA861. The hyperreactivity could be mimicked by incubation of tracheae with BAL cells from naive animals in the presence of IL-5 and SP. After in vivo administration of either IL-5 or SP, maximal responses to histamine were increased and amounted to 105 +/- 35 and 101 +/- 37%, respectively. Administration of IL-5 but not SP induced a significant increase in the number of eosinophils (67 +/- 22%) and eosinophil peroxidase (EPO) activity (94 +/- 33%) in BAL cells. The simultaneous administration of IL-5 and SP did not potentiate the hyperreactivity and eosinophilia observed with IL-5 alone. These data suggest that IL-5 is important in the recruitment of eosinophils, whereas both IL-5 and substance P are involved in the induction of airway hyperreactivity.

Animals↗
PubMed1995

Eosinophil infiltration precedes development of airway hyperreactivity and mucosal exudation after intranasal administration of interleukin-5 to mice.

Recently, we demonstrated that antibody to interleukin-5 (IL-5) prevents the infiltration of eosinophils in the respiratory airways and the development of bronchial hyperreactivity in an animal model of allergic asthma. In this study we investigated the influence of long-term intranasal administration of IL-5 on airway responsiveness in vitro, the infiltration of inflammatory leukocytes, and mucosal exudation. Mice (BALB/c) received 1 microgram of recombinant human IL-5 in 30 microliters of saline solution or vehicle alone twice a day for 1, 3, and 7 days. At 3 and 7 days after IL-5 administration, the number of bronchoalveolar lavage eosinophils increased approximately fourfold and sixfold, respectively. Blood eosinophil numbers showed a similar increase. In addition, 7 days after IL-5 treatment, total lung eosinophil peroxidase activity was significantly increased by 170% as compared with controls. The maximal responsiveness of the trachea in vitro to methacholine was significantly increased by 34%, as compared with controls, only at 7 days after IL-5 administration. Furthermore, mucosal exudation was also only increased significantly at 7 days after IL-5 administration. It can be concluded that the IL-5-induced eosinophil infiltration precedes the development of airway hyperreactivity and mucosal exudation.

Administration, Intranasal↗
PubMed1993

Recombinant interleukin-5 induces in vivo airway hyperresponsiveness to histamine in guinea pigs.

Interleukin-5-producing CV-1 cells were encapsulated in alginate and injected i.p. in guinea pigs (4 x 10(6)/animal). These cells produced approximately 8 ng interleukin-5 per 4 x 10(6) cells per day. Airway hyperresponsiveness to histamine in vivo was observed 3 and 7 days after administration. The increase in lung resistance after intravenous administration of histamine to guinea pigs was significantly potentiated, by approximately 70 to 90% in interleukin-5-treated animals. In animals treated with antibody to interleukin-5, the administration of interleukin-5-producing CV-1 cells did not induce hyperresponsiveness. The percentage of eosinophils in broncho-alveolar lavage fluid was increased by 100% at 7 days but not at 3 days after administration of interleukin-5-producing CV-1 cells. Antibody to interleukin-5 prevented the broncho-alveolar lavage eosinophilia at 7 days after interleukin-5 administration. It can be concluded that interleukin-5 induces broncho-alveolar lavage eosinophilia and airway hyperresponsiveness and that these phenomena do not occur simultaneously. These data suggest a role for interleukin-5 in the development of airway hyperresponsiveness in bronchial asthma.

Airway Resistance↗
PubMed1991

5-HT1-like receptors mediate potentiation of cholinergic nerve-mediated contraction of isolated mouse trachea.

While it had no effect on the resting tension of mouse tracheal segments, 5-HT (10(-8)-10(-4) M) potentiated concentration dependently the contractions induced by electrical field stimulation (EFS). The maximal potentiation was 105 +/- 38% and the EC50 value was 1.4 +/- 0.6 x 10(-6) M (n = 6). The responsiveness of mouse trachea to acetylcholine was not altered by 5-HT (10(-5) M). The 5-HT1A,B antagonist pindolol (10(-6) M), the combined 5-HT2 and 5-HT1C receptor antagonist, ketanserin (10(-6) M), or the combined 5-HT1 and 5-HT2 receptor antagonist, methysergide (10(-6) M), all partially inhibited the effect of 5-HT on the twitch responses. Blockade of 5-HT3 receptors by GR 38032F (10(-6) M) did not affect the potentiation by 5-HT. Antagonism of 5-HT3 and 5-HT4 receptors by ICS 205,930 (3 x 10(-6) M) increased the potentiation of the twitch responses by 5-HT, this was probably due to a decrease of the baseline EFS-induced twitch response by ICS 205,930. Alkylation of the 5-HT2 receptor by phenoxybenzamine (3 x 10(-7) M) treatment did not significantly affect the potentiation of the twitch responses by 5-HT. The beta-adrenoceptor antagonist, timolol (10(-6) M), and the alpha-adrenoceptor antagonist, phentolamine (10(-6) M), did not influence the potentiation of the twitch responses by 5-HT, excluding the involvement of the adrenergic system.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1983

Low oral bioavailability of hexamethylmelamine in the rat due to simultaneous hepatic and intestinal metabolism.

The disposition of both hexamethylmelamine (HMM) after intraarterial, i.v., portal vein, and intraduodenal administration and of pentamethylmelamine following its i.v. administration was studied in male Wistar rats. HMM (5 and 10 mg/kg) and pentamethylmelamine (5 mg/kg) were infused via implanted cannulas into conscious animals (n greater than or equal to 4). Plasma levels of parent compound and of metabolites were determined by gas chromatography. The areas under the plasma concentration-time curves of HMM following its intraarterial and i.v. administration were not significantly different, indicating that HMM was not appreciably metabolized in the lung. Areas under plasma-concentration-time curves of HMM following portal vein and intraduodenal administration were 27 and 8% of the area under the plasma concentration-time curve after i.v. administration, respectively. Absorption of HMM was complete as judged from metabolite data. The reduced bioavailability of HMM intraduodenally was thus a consequence of presystemic elimination in the liver and the gut wall. Extraction ratios (or first-pass effects) of the liver and the gut wall were 73 and 71%, respectively. Linear kinetic behavior of HMM i.v. was observed in the 5- to 10-mg/kg dose range. Extensive gut wall metabolism may have important implications for the antitumor activity mechanism of HMM.

Altretamine↗