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Biomedical subjects

W W Busse

Publications and source records attributed to W W Busse.

At least 19 recordsLinked to original sources
PubMed1995

Differential effects of granulocyte-macrophage colony-stimulating factor on eosinophil and neutrophil superoxide anion generation.

Eosinophils (EOS) are specifically recruited to sites of allergic inflammation and parasitic infection, while neutrophil (NEUT) influx predominates in bacterial infections. This biologic selectivity suggests that granulocytes may respond differently to inflammatory mediators such as granulocyte-macrophage-CSF (GM-CSF). To establish the mechanisms of the response of granulocytes to GM-CSF, isolated human peripheral blood EOS and NEUT were obtained from allergic rhinitis patients and incubated in vitro with this cytokine. Incubation with GM-CSF (10 or 100 pM) significantly enhanced FMLP-stimulated EOS superoxide anion (O2-) generation, LTC4 release, and adhesion to tissue culture plates. Both GM-CSF-enhanced EOS adhesion and O2- generation were inhibited by an anti-beta 2 (CD18) Ab suggesting that this beta 2 integrin was associated with increased cell function. In contrast, FMLP + cytochalasin B were required to demonstrate GM-CSF enhancement of NEUT O2- and LTB4 generation; GM-CSF had no effect on NEUT adhesion. Furthermore, GM-CSF augmentation of FMLP + cytochalasin B-activated NEUT O2- generation was not affected by anti-beta 2 Ab but was blocked by a 5-lipoxygenase-activating protein antagonist, BAY x 1005. Finally, 0.1 to 10 nM LTB4 mimicked the GM-CSF-priming effect on NEUT O2- generation, thus suggesting that the augmented NEUT respiratory burst was the result of LTB4 production and its effect on the NEUT. These data demonstrate that GM-CSF promotes EOS and NEUT O2- generation to FMLP via distinct mechanisms: enhanced adhesion of EOS vs autocrine-priming by enhanced LTB4 generation of NEUT.

Adult↗
PubMed1995

Eosinophil adhesion to vascular cell adhesion molecule-1 activates superoxide anion generation.

Adhesion to the adhesion protein, VCAM-1, on vascular endothelium is proposed to be an important factor in the selective accumulation of eosinophils at sites of allergic inflammation. To determine whether eosinophil adhesion to VCAM-1 is also associated with an alteration of eosinophil function, human peripheral blood eosinophils were isolated from allergic donors and incubated in VCAM-1-coated wells. Spontaneous adherence of isolated eosinophils to VCAM-1-coated wells was greater than cells incubated in FCS-treated control wells (38.0 +/- 1.6% vs 17.1 +/- 1.9%, n = 16, p < 0.0001). In addition, eosinophils incubated in VCAM-1-coated wells spontaneously generated modest but significant amounts of superoxide anion (O2-; 2.0 +/- 1.3 vs 00.5 +/- 0.5 nmol/5 x 10(5) cells, n = 9, p = 0.029). Moreover, when 100 nM FMLP was added to eosinophils in the presence of VCAM-1, significantly greater O2- generation occurred (7.2 +/- 0.9 vs 5.4 +/- 1.0 (FCS control) nmol/5 x 10(5) cells, n = 9, p = 0.009). Adhesion, as well as the spontaneous and enhanced O2- generation to FMLP activation, was blocked by the monoclonal anti-alpha 4 integrin Ab, HP 1/2, implying involvement of an alpha 4 integrin-VCAM-1 interaction. In contrast, the anti-CD18 mAb, L130, inhibited the spontaneous and enhanced O2- generation to FMLP without affecting adhesion, suggesting an involvement of CD18 molecule(s) only in VCAM-1-enhanced respiratory burst. Finally, 1 microM genistein, a tyrosine kinase inhibitor suppressed the VCAM-1-enhancing effect on eosinophil O2- generation and VCAM-1-induced tyrosine phosphorylation, suggesting a role for tyrosine phosphorylation in this eosinophil functional up-regulation. Our observations suggest that eosinophil adhesion to VCAM-1 may be an important step in determining the eventual functional activity of these cells as they migrate from the circulation to the airways and contribute to the allergic inflammatory process.

Adult↗
PubMed1995

Effect of interleukin-5 and granulocyte-macrophage colony stimulating factor on in vitro eosinophil function: comparison with airway eosinophils.

Eosinophils are hypothesized to be crucial in the development of allergic airway inflammation; however, the actual mechanisms that determine their inflammatory activity are still largely undefined. To investigate the factors that regulate eosinophil function in allergic airway disease, we have previously used segmental bronchoprovocation with allergen to study ex vivo eosinophil function. To determine whether the functional changes associated with airway eosinophils obtained by bronchoalveolar lavage 48 hours after antigen challenge are caused by exposure to airway-generated cytokines, normodense blood eosinophils were cultured in vitro with recombinant human interleukin-5 (IL-5) or granulocyte-macrophage colony stimulating factor (GM-CSF). The effect of cytokine exposure was then evaluated on selected cell functions. In vitro incubation with these cytokines for 24 hours significantly increased eosinophil membrane expression of CD18 and CD11b compared with culture in medium alone or eosinophils obtained by bronchoalveolar lavage. N-formyl-methionyl-leucyl-phenylalanine-stimulated superoxide anion generation was slightly but significantly enhanced by incubation with IL-5 but not with GM-CSF. In addition, spontaneous adhesion to human umbilical vein endothelial cell monolayers was increased after exposure to both IL-5 and GM-CSF. However, activated adhesion was enhanced only by culture with IL-5 and stimulation with N-formyl-methionyl-leucyl-phenylalanine. The magnitude of functional changes after in vitro preincubation of eosinophils with these cytokines did not achieve levels of superoxide anion and adhesion noted with airway eosinophils obtained after segmental bronchoprovocation with allergen. These observations raise the possibility that the contribution of IL-5 and GM-CSF to phenotypic changes of airway eosinophils is principally to enhance survival and expression of adhesion proteins. These data also suggest that, in addition to the generation of proinflammatory cytokines, other factors contribute to phenotypic changes in eosinophils as they migrate from the blood to the airway.

Blood Cells↗
PubMed1995

Viral infections in humans.

Viral respiratory infections can increase asthma symptoms in many patients. Although the mechanisms of these effects are not fully established, there is evidence that respiratory viruses can promote some components of allergic inflammation. In this regard, there is evidence that rhinovirus respiratory infections can lead to the development of late allergic reactions to inhaled allergen. This change in response to inhaled allergen supports the possibility that some respiratory infection will promote bronchial inflammation and may be a factor for increased wheezing with respiratory infection.

Allergens↗
PubMed1995

Mechanisms of persistent airway inflammation in asthma. A role for T cells and T-cell products.

The role of T cells in human allergic inflammation is just beginning to be understood. However, the data presented indicate how the T cell may be a pivotal cell to direct features of allergic inflammation in asthma, how the T cell may be able to transfer hyperresponsiveness, which is a feature of bronchial asthma, what some of the genetic factors are that may determine this process, and how an important precipitant of asthma, viral respiratory infections, may participate in this process. Its cells are isolated from patients with asthma and studied for their ability to generate proinflammatory failure. An expanded understanding of the chronic, persistent nature of asthma will become apparent.

Animals↗
PubMed1995

Fluticasone propionate reduces oral prednisone use while it improves asthma control and quality of life.

This study examined the ability of fluticasone propionate aerosol to reduce oral prednisone requirements in patients with severe asthma. Ninety-six patients dependent on oral prednisone were treated for 16 wk with placebo or fluticasone propionate aerosol (750 or 1,000 micrograms twice daily). Their dosage of oral prednisone was adjusted weekly according to predetermined criteria. A total of 69% and 88% of patients treated with fluticasone propionate 750 and 1,000 micrograms twice daily, respectively, compared with 3% of placebo-treated patients used no prednisone by the end of the study. In the fluticasone propionate groups, FEV1 and peak expiratory flow rates at the last evaluable visit/date improved and the number of night awakenings and symptomatic albuterol use declined relative to placebo values (p < 0.05). Patient-rated asthma symptoms improved in the groups receiving fluticasone propionate but not in the placebo group (p < 0.005). Fluticasone propionate aerosol was well-tolerated, and it improved some dimensions of health-related quality of life measured using a standard patient survey. Fluticasone propionate aerosol (750 or 1,000 micrograms twice daily) effectively and safely allowed most asthmatics dependent on oral corticosteroids to reduce or eliminate oral prednisone use while improving pulmonary function and quality of life.

Administration, Inhalation↗
PubMed1995

Cytokines in bronchoalveolar lavage fluid of patients with nocturnal asthma.

Airflow obstruction can have a circadian pattern with nocturnal worsening. Airway inflammation is a cardinal feature of asthma, and it has been shown to increase at night in association with the decline in pulmonary function. Although the mechanisms regulating enhanced airway inflammation in asthma at night have yet to be ascertained, we hypothesized that circadian variation in cytokine expression or production is an important factor in the development of nocturnal airflow limitation. To investigate this possibility, spirometry and bronchoscopy were performed; the bronchoalveolar lavage (BAL) fluid obtained at 4:00 A.M. and at 4:00 P.M. were measured for IL-1 beta in asthmatics with (n = 5) and without (n = 9) nocturnal asthma. In addition, the activity of IL-3, IL-5, and GM-CSF was measured using a biologic assay (eosinophil survival-enhancing activity). BAL fluid concentrations of IL-1 beta were significantly greater at 4:00 A.M. than at 4:00 P.M. (1.14 +/- 0.6 versus 0.7 +/- 0.6 pg/ml; p = 0.05) in asthmatics with nocturnal airflow obstruction. Moreover, IL-1 beta levels at 4:00 A.M. tended to be higher in subjects with nocturnal asthma than in those without nighttime airflow reduction (1.14 +/- 0.6 versus 0.3 +/- 0.4 pg/ml; p = 0.1). On the other hand, eosinophil survival-enhancing activity in BAL fluid, which is usually associated with IL-3, IL-5, or GM-CSF, was not detected in relationship to nocturnal asthma. Because IL-1 beta can activate air-space cells, particularly alveolar macrophages, we propose that an increased release of this cytokine is a significant contributor to nocturnal airway inflammation and obstruction in asthma.

Adolescent↗
PubMed1995

The effects of rhinovirus infections on allergic airway responses.

Although it has long been recognized that the common cold is a potent trigger for symptoms of asthma, the mechanisms underlying the association between upper respiratory infection and increased lower airway obstruction remain obscure. The use of experimental infection of volunteers with or without respiratory allergies has enabled direct comparisons of common cold symptoms in these two groups. Furthermore, techniques such as bronchoalveolar lavage and segmental antigen challenge have been used to directly sample lower airway fluids and tissues during acute viral infection. This review summarizes the findings of studies examining the separate and combined effects of rhinovirus infection and allergen exposure on airway physiology and inflammation.

Asthma↗
PubMed1995

Adhesion of activated eosinophils to respiratory epithelial cells is enhanced by tumor necrosis factor-alpha and interleukin-1 beta.

Eosinophilic infiltration and damage to airway epithelium are characteristic features of asthma. To assess possible interactions between eosinophils and airway epithelium, Percoll-purified human peripheral blood eosinophils were evaluated for their ability to adhere to respiratory epithelial cell (REC) cultures. REC (an immortalized cell line, A549, and primary bronchial epithelial cells) were grown in 96-well tissue culture plates, treated with proinflammatory cytokines (TNF-alpha or IL-1 beta), and eosinophil adhesion to these tissues was determined. Cytokine treatment of the REC cultures significantly increased expression of intercellular adhesion molecule-1 (ICAM-1) (P < 0.01). Eosinophils demonstrated a variable baseline adhesion to untreated REC which was then significantly increased following activation with phorbol myristate acetate (PMA) (P < 0.01). Furthermore, treatment of REC monolayers with TNF-alpha or IL-1 beta significantly increased adhesion of PMA-stimulated eosinophils (P < 0.01). To delineate the adhesion proteins involved in the cell-cell interactions, assays were performed in the presence of specific blocking monoclonal antibodies to eosinophil CD18, CD11a, or CD11b, and REC ICAM-1 molecules. Blocking antibodies to ICAM-1 had no significant effect on levels of eosinophil adhesion. In contrast, antibodies to CD18, CD11a, and CD11b significantly decreased (P < 0.01) eosinophil adhesion, thus demonstrating pivotal roles for the CD11/CD18 (beta 2) integrins, but not necessarily for ICAM-1, in interactions between the REC and eosinophils. These data demonstrate that TNF-alpha and IL-1 beta increase eosinophil adhesion to human respiratory epithelial cell cultures by induction of ligands recognized by eosinophil beta 2 integrins.

Asthma↗
PubMed1994

Eosinophil eicosanoid relations in allergic inflammation of the airways.

Eosinophils are prominent features of allergic inflammation and can contribute to this process through release of inflammatory enzymes, granule-associated proteins, and leukotriene products. There is considerable interest in the fact that selected cytokines enhance eosinophil generation of leukotrienes. Therefore, future directions must include efforts to identify factors that regulate eosinophil synthesis of leukotrienes and therapeutic agents that might control these specific inflammatory responses.

Asthma↗
PubMed1994

Eosinophil as a therapeutic target in allergic disease.

The eosinophil appears to be a key cell in the development of active symptoms in both allergic diseases and asthma. Its involvement in inflammation seems to be mediated in part by release of its mediators ECP, MBP, EPO, and EDN. Therefore, the eosinophil and its inflammatory mediators would make ideal targets for pharmacological manipulation. In designing therapeutics to modify eosinophil participation, it will be helpful to keep the pharmacologic regulation as eosinophil-specific as possible. In this way, The function of other granulocytes is not affected and the patient is still able to fight infections.

Asthma↗
PubMed1994

Role of antihistamines in allergic disease.

Both first-generation and second-generation antihistamines effectively reduce symptoms of sneezing, rhinorrhea, and nasal pruritus in individuals with allergic disease. These agents act as competitive inhibitors of histamine (a principal mediator of the allergic response) at various target-organ sites. Although the classic, first-generation antihistamines are unable to halt the allergic reaction once it has begun, emerging evidence has suggested that newer, second-generation agents may interfere with the release of inflammatory mediators from mast cells or may inhibit eosinophil chemotaxis. These effects may confer additional clinical benefit. Also, the second-generation agents produce fewer adverse reactions, including a marked reduction in sedation. Contrary to previous recommendations, recent findings have suggested that antihistamines may not necessarily be contraindicated in patients who have both asthma and allergic rhinitis. A greater understanding of the mechanisms of action and clinical effects of both older-generation and newer-generation antihistamines should help define optimal therapeutic strategies in the future.

Histamine Antagonists↗
PubMed1992

Comparison of airway and blood eosinophil function after in vivo antigen challenge.

Eosinophils (EOS) are important effector cells in allergic diseases and asthma. However, functional characteristics of the EOS have been derived primarily from studies of blood cells, and it is unlikely that such assessments reflect events occurring in tissues or airways. To establish more precisely the function of airway EOS, segmental Ag challenge was used to elicit and isolate large numbers of these cells. Airway, as well as blood, EOS were isolated from allergic patients 48 h after segmental Ag challenge. Both blood and bronchoalveolar lavage (BAL) EOS were fractionated over Percoll density gradients; by using this protocol, three density-distinct populations of pure (>90%) EOS were obtained from BAL fluid (1.100, 1.095, and 1.090 g/ml) and one from blood (1.100 g/ml). The functions of these various populations were compared by measuring superoxide generation, adherence to collagen and endothelial cell monolayers, cell surface receptors, and in vitro survival. BAL EOS of all three densities had greater superoxide generation and adherence with FMLP activation than did corresponding blood EOS. In contrast, blood and airway EOS responded similarly to PMA. BAL EOS also had increased expression of CD11b/CD18 and HLA-DR. The intracellular calcium concentration ([Ca2+]i) was measured with the fluorescent marker indo-1/acetoxymethyl ester. FMLP caused a greater and more sustained increase in [Ca2+]i with BAL than blood EOS. EGTA blocked the sustained component of the [Ca2+]i response to FMLP. Our findings indicate that BAL EOS have an enhanced [Ca2+]i response to activation that may contribute to their functional up-regulation.

Adult↗
PubMed1992

Inhibition of eosinophil density change and leukotriene C4 generation by nedocromil sodium.

Nedocromil sodium (NS) has been shown to inhibit the late asthma response to inhaled antigen and to control symptoms in chronic asthma; in both processes the eosinophil is thought to be an important contributor. To understand the antiinflammatory actions of NS in asthma, its effects on three eosinophil functions were evaluated: (1) change in cell density during in vitro culture, (2) synthesis of leukotriene C4 (LTC4), and (3) generation of superoxide anion. In these studies normal density (greater than 1.095 gm/ml) purified human peripheral blood eosinophils were cultured for 24 hours in 50% conditioned medium from cow pulmonary arterial endothelial cells. After incubation, 45.2% +/- 8.0% of the eosinophils had a density less than 1.085 gm/ml. In the presence of NS (10 mumol/L), only 32.0% +/- 7.3% became less dense (p = 0.0393). In contrast, NS had no effect on changes in cell density after a 20-minute exposure of eosinophils to functional activators N-formyl-methionyl-leucyl-phenylalanine (0.1 mumol/L) or platelet activating factor (0.1 mumol/L). Furthermore, calcium ionophore-activated LTC4 secretion was found to be significantly inhibited by NS (3.8 +/- 0.6 ng/ml vs. 2.4 +/- 0.3 ng/ml with 1 mumol/L NS or 1.7 +/- 0.6 ng/ml with 10 mumol/L NS, p less than 0.025). However, NS did not significantly alter eosinophil superoxide anion generation. The effects of NS on eosinophil function suggest a mechanism by which this medication may be effective in asthma, particularly in the regulation of the late asthmatic response. Furthermore, the selective regulatory effects of NS may also provide insight into the biologic activities of eosinophils.

Adult↗
PubMed1992

Respiratory infections and asthma.

Airway responsiveness is increased during respiratory virus infections, both in subjects with asthma and without underlying pulmonary disease. Furthermore, the airway hyperresponsiveness is altered for a prolonged period of time, weeks or months after the viral illness has subsided. This article reviews the possible mechanisms of virus-associated airway hyperresponsiveness, including the complex interplay of IgE-dependent reactions, changes in autonomic nervous system function and inflammation, epithelial damage, effects of viruses on the cellular immune response, and enhanced late-phase response.

Adrenal Cortex Hormones↗