Targeting granulocyte-macrophage colony-stimulating factor in epithelial and vascular remodeling in experimental eosinophilic esophagitis.

BACKGROUND: Eosinophilic esophagitis (EoE) is a chronic antigen-mediated clinicopathologic disease of the esophagus characterized by an eosinophil-predominant inflammatory infiltrate. A clinical hallmark is extensive tissue remodeling including basal zone hyperplasia, fibrosis, and angiogenesis. However, the cellular mechanisms responsible for these processes are not fully defined. We hypothesized that targeting granulocyte-macrophage colony-stimulating factor (GM-CSF; an agonist cytokine linked with eosinophil survival and activation) would be protective in a preclinical model of EoE. METHODS: Eosinophilic esophagitis-like esophageal inflammation was induced in the L2-IL5OXA EoE mouse model, and GM-CSF production was assessed by mRNA and protein analyses. Granulocyte-macrophage colony-stimulating factor-receptor-alpha expression patterns were examined by flow cytometric and immunofluorescence analysis. L2-IL5OXA EoE mice were treated with anti-GM-CSF neutralizing antibody or isotype control and assessed for histopathological indices of eosinophilia, epithelial hyperplasia, and angiogenesis by immunohistochemistry and RT-PCR. RESULTS: Significantly increased levels of esophageal GM-CSF expression was detected in the L2-IL5OXA mouse EoE model during active inflammation. Granulocyte-macrophage colony-stimulating factor-receptor-alpha was predominantly expressed on esophageal eosinophils during EoE, in addition to select cells within the lamina propria. Anti-GM-CSF neutralization in L2-IL5OXA EoE mice resulted in a significant diminution of epithelial eosinophilia in addition to basal cell hyperplasia and vascular remodeling. This treatment response was independent of effects on esophageal eosinophil maturation or activation. CONCLUSION: Granulocyte-macrophage colony-stimulating factor is a potential therapeutic target to reduce esophageal eosinophilia and remodeling.

Up-regulation of CCL11 and CCL26 is associated with activated eosinophils in bullous pemphigoid.

Eosinophils contribute to the pathogenesis of bullous pemphigoid (BP) by secretion of proinflammatory cytokines and proteases. Trafficking of eosinophils into tissue in animal models and asthma depends on interleukin-5 and a family of chemokines named eotaxins, comprising CCL11, CCL24 and CCL26. Up-regulation of CCL11 has been described in BP, but the expression of the other two members of the eotaxin-family, CCL24 and CCL26, has not been investigated. In addition to these chemokines, expression of adhesion molecules associated with eosinophil migration to the skin should be analysed. We demonstrate that similar to CCL11, the concentration of CCL26 was up-regulated in serum and blister fluid of BP patients. In contrast, the concentration of CCL24 was not elevated in sera and blister fluid of the same BP patients. In lesional skin, CCL11 and CCL26 were detected in epidermis and dermis by immunohistochemistry. In contrast to CCL11, CCL26 was expressed strongly by endothelial cells. In line with these findings, eosinophils represented the dominating cell population in BP lesional skin outnumbering other leucocytes. The percentage of eosinophils expressing very late antigen (VLA): VLA-4 (CD49d) and CD11c correlated with their quantity in tissue. Macrophage antigen (MAC)-1 (CD11b/CD18) was expressed constitutively by tissue eosinophils. In conclusion, these data link the up-regulation of the eosinophil chemotactic factor CCL26 in BP to the lesional accumulation of activated eosinophils in the skin. Thereby they broaden the understanding of BP pathogenesis and might indicate new options for therapeutic intervention.

Mechanism of eosinophilic esophagitis.

Eosinophilic esophagitis (EoE) is a newly recognized disease and is an emerging entity throughout developing and developed countries, including the United States. Therefore, understanding the causes, natural history, diagnosis, and management is important for future therapeutic interventions. The pathogenesis of EoE is still not clear, but a growing body of evidence has established that this condition represents a T-cell-mediated immune response involving several proinflammatory mediators and chemoattractants known to regulate eosinophilic accumulation in the esophagus, such as IL-4, IL-5, IL-3 and eotaxin-1, -2, and -3. Determining the mechanism or mechanisms through which human esophageal-derived factors ultimately induce the functional abnormalities observed, and to which antigens patients who have EoE are sensitized that lead to the manifestation of symptoms, is of significant interest.

Relationships between eosinophilic inflammation, tissue remodeling, and fibrosis in eosinophilic esophagitis.

The clinical and pathologic features of eosinophilic esophagitis (EE) include extensive tissue remodeling. Increasing evidence supports a key role for the eosinophil in multiple aspects of the esophageal remodeling and fibrosis seen in this allergic disease. This article reviews the clinical implications of esophageal remodeling and fibrosis in EE and discusses the possible pathogenic mechanisms inducing and regulating these responses. The focus is specifically on eosinophil and cytokine interactions with the esophageal epithelium, vascular endothelium, resident fibroblasts, and smooth muscle. Current and potential therapeutic interventions are discussed that may impact the development or resolution of chronic esophageal remodeling and fibrosis in EE.

Hierarchy of eosinophil chemoattractants: role of p38 mitogen-activated protein kinase.

Several chemoattractants can regulate the recruitment of eosinophils to sites of inflammation, but the hierarchy among them is unknown. We observed here that eosinophil chemotaxis towards eotaxin or 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) was amplified up to sixfold in the presence of prostaglandin (PG) D2. This effect was only seen in eosinophils, and not in neutrophils or basophils. Pretreatment with the chemoattractant receptor-homologous molecule expressed on TH2 cells (CRTH2) antagonist ramatroban prevented the PGD2 enhancement of eosinophil migrations. In contrast, eotaxin or 5-oxo-ETE inhibited the migration of eosinophils towards PGD2. 5-oxo-ETE enhanced the chemotaxis to eotaxin, while eotaxin had no effect on 5-oxo-ETE-induced migration. 5-oxo-ETE induced the phosphorylation of p38 mitogen-activated protein kinase, and inhibition of p38 mitogen-activated protein kinase by SB-202190 converted the effect of 5-oxo-ETE on the chemotaxis to PGD2 from inhibition to enhancement. The presence of blood or plasma markedly decreased the sensitivity of eosinophils to eotaxin or 5-oxo-ETE, while responses to PGD2 were unaltered. In conclusion, PGD2 might be an initial chemoattractant, since it maintains its potency in the circulation and augments the responsiveness of eosinophils to other chemoattractants. In contrast, eotaxin seems to be an end-point chemoattractant, since it has reduced efficacy in blood and is capable of down-modulating eosinophil responsiveness to other chemoattractants.

Effects of a reversible beta-tryptase and trypsin inhibitor (RWJ-58643) on nasal allergic responses.

BACKGROUND: beta-Tryptase is a multifunctional mast cell serine protease released during mast cell degranulation and tryptase/trypsin inhibitors are a novel potential therapeutic approach for allergic inflammatory diseases. OBJECTIVES: This study was performed to assess the effects of RWJ-58643 on nasal symptoms, eosinophil influx, and cytokine and chemokine release following nasal allergen challenge (NAC). METHODS: Male patients with grass pollen allergic rhinitis (n=16) out of season received single doses of RWJ-58643 (100, 300, 600 microg) or matched placebo given 30 min before NAC in a double-blind, randomized crossover design. A single dose of 200 microg budesonide was studied in an open-label extension phase. NAC was performed with Timothy grass pollen (ALK) via a nasal device, and nasal lavage was performed at times 0 (pre-drug, pre-allergen), 0.5 (30 min post-drug, pre-NAC) 1.5, 2.5, 4.5, 6.5, 8.5, and 24 h after drug administration. Nasal lavage mediators were analysed using a sensitive multiplexed bead immunoassay system. RESULTS: Low-dose RWJ-58643 (100 microg) and budesonide (200 microg) significantly reduced symptoms, eosinophils and levels of IL-5 following NAC. However, higher doses of RWJ-58643 (300 and 600 microg) caused a late eosinophilia and preceding increases in IL-5 compared with placebo. CONCLUSIONS: This study suggests that combined beta-tryptase and trypsin inhibition has therapeutic potential in allergic inflammation, however, this property is dose responsive and higher doses are ineffective and may cause eosinophilia.

IL-17E upregulates the expression of proinflammatory cytokines in lung fibroblasts.

BACKGROUND: IL-17E is a new TH2 cytokine that promotes airway eosinophilia in mice. IL-17E proinflammatory activity has been proposed to involve induction of cytokine and chemokine production. Recruitment of inflammatory cells may be mediated by tissue-resident cells. OBJECTIVE: This study aimed to evaluate whether fibroblasts represent a target of IL-17E for the production of eosinophil active mediators in the lung. METHODS: Expression of IL-17B receptor (IL-17BR), a receptor for IL-17E, was evaluated by immunofluorescent staining, Western blot, and real-time PCR in human primary lung fibroblasts. Mediator production was analyzed by using real-time PCR and ELISA after stimulation of fibroblasts with IL-17E alone or in combination with TNF-alpha and TGF-beta1. Expression of IL-17E and of eosinophil major basic protein was evaluated by immunohistochemistry in bronchial biopsies from subjects with asthma. RESULTS: Human primary lung fibroblasts constitutively expressed IL-17BR. IL-17BR mRNA levels were increased in cells stimulated with TNF-alpha and decreased with TGF-beta1. IL-17E slightly upregulated CC chemokine ligand (CCL)-5, CCL-11, GM-CSF, and CXC chemokine ligand (CXCL)-8 mRNA in fibroblasts. Moreover, IL-17E and TNF-alpha synergistically induced GM-CSF and CXCL-8 mRNA. IL-17E also potentiated the upregulation of CXCL-8 transcripts observed with TGF-beta1. In contrast, TGF-beta1 decreased IL-17E-induced CCL-11 mRNA. The capacity of IL-17E to enhance GM-CSF and CXCL-8 responses to TNF-alpha was accompanied by production and secretion of both proteins by lung fibroblasts. Finally, IL-17E was detected in asthma in eosinophil-infiltrated bronchial submucosa. CONCLUSION: IL-17E may contribute to the induction and maintenance of eosinophilic inflammation in the airways by acting on lung fibroblasts. This study supports a role for IL-17E in asthma pathophysiology.

Modulation of murine experimental asthma by Ascaris suum components.

BACKGROUND: We have recently isolated two distinct components from Ascaris suum adult worms with different effects on the immune system: the allergenic protein of A. suum (APAS-3), which induces IgE antibody production, and suppressive protein of A. suum (PAS-1), which inhibits humoral and cellular immune responses induced by unrelated antigens. In this study, we investigated the immunomodulatory effect of PAS-1 on a murine model of asthma induced by APAS-3. METHODS: BALB/c mice were immunized twice with APAS-3 or APAS-3 plus PAS-1 by the intraperitoneal and subcutaneous route (on days 0 and 7) and challenged twice with the same antigens intranasally (days 14 and 21). Two days after the last challenge, the allergic airway inflammation was evaluated by cellular migration, eosinophil peroxidase (EPO) activity, cytokine and chemokine production and pulmonary mechanical parameters. RESULTS: The allergenic properties of APAS-3 were confirmed by the stimulation of anaphylactic IgE and IgG1 antibody production and eosinophilic airway inflammation and hyper-responsiveness. On the other hand, PAS-1-treated mice showed a marked suppression of cellular migration and EPO activity that correlated well with a significant reduction in the levels of IL-4, IL-5, eotaxin and RANTES in the bronchoalveolar lavage (BAL) fluid. In contrast, considerable amounts of IL-10 were observed in the BAL fluid of PAS-1-treated mice. Airway hyper-responsiveness was obtained in APAS-3-immunized mice, but the conductance of the respiratory system was restored to normal values in the presence of PAS-1. CONCLUSION: These results indicate that A. suum allergenic protein APAS-3 induces a T helper 2-type immune response and, consequently, eosinophilic airway inflammation and hyper-responsiveness. Moreover, the modulatory protein PAS-1 has a marked suppressive effect on this response, and the inhibition of cytokine (IL-4, IL-5) and chemokine (eotaxin and RANTES) release, probably because of the presence of IL-10, may contribute to this effect.

Selective suppression of leukocyte recruitment in allergic inflammation.

Allergic diseases result in a considerable socioeconomic burden. The incidence of allergic diseases, notably allergic asthma, has risen to high levels for reasons that are not entirely understood. With an increasing knowledge of underlying mechanisms, there is now more potential to target the inflammatory process rather than the overt symptoms. This focuses attention on the role of leukocytes especially Th2 lymphocytes that regulate allergic inflammation and effector cells where eosinophils have received much attention. Eosinophils are thought to be important based on the high numbers that are recruited to sites of allergic inflammation and the potential of these cells to effect both tissue injury and remodelling. It is hoped that future therapy will be directed towards specific leukocyte types, without overtly compromising essential host defence responses. One obvious target is leukocyte recruitment. This necessitates a detailed understanding of underlying mechanisms, particularly those involving soluble chemoattractants signals and cell-cell adhesion molecules.

Bovine eotaxin (CCL11)--an unusual member of the eotaxin group--attracts eosinophils in vitro but is not responsible for eosinophilia in the ovary.

Under physiological conditions normally characterised by low tissue infiltration of eosinophils, a conspicuous number of these cells are attracted into the human and ruminant ovary. Eosinophils suddenly increase in the thecal layer of the preovulatory follicle and corpus luteum at very early development. Currently, we only have a limited understanding of the mechanism for the recruitment of the ovarian eosinophils. Eotaxin (CCL11) may be one of the chemoattractants involved in stimulating eosinophils to migrate selectively into ovary. As a prerequisite for the analysis of eotaxin expression in the bovine ovary, we determined the complete bovine eotaxin mRNA sequence since it was not available from databases. The bovine eotaxin is the first member of the monocyte chemoattractant protein (MCP)/eotaxin subfamily with two mRNA isoforms varying in length in the untranslated 3'-untranslated region. The unusual amino-acid sequence of bovine eotaxin contains structural features that are so far known to be characteristic for MCP, but not eotaxin. In our microchemotaxis assays, recombinant bovine eotaxin showed a functional pattern orthologous to known eotaxins. Thus, the chimeric structure of bovine eotaxin did not affect the favoured chemotactic activity on eosinophils. Semiquantitative RT-PCR was used to investigate the expression of eotaxin in different regions of the bovine ovary. We only detected faint eotaxin mRNA signals that did not indicate physiological significance even in stimulated granulosa cell cultures, follicle-derived macrophages or fibroblasts. Taken together, bovine eotaxin attracts eosinophils in vitro but is not responsible for eosinophilia in the ovary. Its unusual chimeric structure confirms the unity of the MCP/eotaxin subfamily of CC chemokines and distinguishes it from other CC chemokine subfamilies.

Therapeutic effect of surfactant protein D in allergic inflammation of mite-sensitized mice.

BACKGROUND: Surfactant protein D (SP-D) is involved in the innate immunity within the lung and may have important roles in modulating the inflammatory process of asthma. OBJECTIVE: To examine the potential immunomodulating role of SP-D on the allergic response in mice, and its interaction with the alveolar macrophages (AMs) during allergic inflammation. METHODS: A recombinant 60 kDa fragment of human SP-D (rfh SP-D), Survanta, and budesonide were administrated, respectively, to Der p-sensitive BALB/c mice before or after allergen challenge (AC). Total and differential cell counts, levels of cytokines in bronchoalveolar lavage fluids(BALFs), and levels of Der p-specific IgE and IgG1 antibodies in sera, were assayed. The production of nitric oxide (NO), and inducible NO synthase (iNOS) expression, in AMs, were determined by ELISA and RT-PCR, respectively. RESULTS: Instillation of rfh SP-D to sensitized mice 6 h after AC (therapeutic), but not 24 h before AC (preventive), markedly reduced infiltration of eosinophils, and also reduced levels of IL-4, IL-5, eotaxin, and TNF-alpha but elevated levels of IFN-gamma in the BALF. These effects were comparable with those obtained with budesonide treatment, whereas Survanta did not have a suppressive effect, either before or after AC. There was significant inhibition of NO production in the rfh SP-D pre-treated AMs of allergen-sensitized mice, but not in naive mice. CONCLUSIONS: These results indicate that rfh SP-D has a therapeutic effect on allergen-induced bronchial inflammation, and that this might be because of its inhibitory effect on NO and TNF-alpha production by AMs, and it thus prevents the development of T-helper type 2 cytokine response.

Selective suppression of leukocyte recruitment in allergic inflammation

Allergic diseases result in a considerable socioeconomic burden. The incidence of allergic diseases, notably allergic asthma, has risen to high levels for reasons that are not entirely understood. With an increasing knowledge of underlying mechanisms, there is now more potential to target the inflammatory process rather than the overt symptoms. This focuses attention on the role of leukocytes especially Th2 lymphocytes that regulate allergic inflammation and effector cells where eosinophils have received much attention. Eosinophils are thought to be important based on the high numbers that are recruited to sites of allergic inflammation and the potential of these cells to effect both tissue injury and remodelling. It is hoped that future therapy will be directed towards specific leukocyte types, without overtly compromising essential host defence responses. One obvious target is leukocyte recruitment. This necessitates a detailed understanding of underlying mechanisms, particularly those involving soluble che-moattractants signals and cell-cell adhesion molecules.

Chemokine receptor antagonists: a novel therapeutic approach in allergic diseases.

The aim of this review is to give an overview of the role of chemokines, particularly ligands of the CC chemokine receptor CCR3, in allergic diseases and to show the new concept in the treatment of allergies using chemokine receptor antagonists. Allergic diseases such as allergic asthma, allergic rhinitis and atopic dermatitis are characterized by a complex interaction of different cell types and mediators. Among this, Th2 cells, mast cells, basophils and eosinophils are found in the inflamed tissue due to the attraction of chemokines. Of all the known chemokine receptors, the chemokine receptor CCR3 seems to play the major role in allergic diseases which is supported by the detection of this receptor on the cell types mentioned above. Therefore, academic and industrial research focus on compounds to block this receptor. To date, certain chemokine receptor antagonists derived from peptides and small molecules exist to block the chemokine receptor CCR3. However, the in vivo data about these compounds and the mechanisms of receptor interaction are poorly understood, as yet. For the development of additional chemokine receptor antagonists, more details about the interaction between the ligands and their receptors are required. Therefore, additional studies will lead to the identification of novel CCR3 chemokine receptor antagonists, which can be therapeutically used in allergic asthma, allergic rhinitis, and atopic dermatitis.

Human airway submucosal glands augment eosinophil chemotaxis during rhinovirus infection.

BACKGROUND: Asthma exacerbations are frequently associated with rhinovirus (RV) infections. However, the contribution of airway submucosal gland (SMG) to exacerbations of asthma in RV respiratory infection has not been studied. OBJECTIVE: This study was undertaken to examine whether RV-infected human respiratory SMG cells produce pro-inflammatory cytokines and chemokines for eosinophils, and augment eosinophil transmigration across human airway epithelium. METHODS: We infected cultured human tracheal SMG cells with RV14, collected culture media at 1, 3, and 5 days after infection, and measured the chemotactic activity for eosinophils in the culture supernatant using a 48-well microchemotaxis chamber and a (51)Cr-labelled eosinophil transmigration assay. RESULTS: Exposing a confluent human tracheal SMG cell monolayer to RV14 consistently led to infection. Human SMG cells with RV infection secreted soluble factors activating human eosinophil chemotaxis into the culture supernatant in a time-dependent manner, and the culture supernatant significantly augmented the transmigration of (51)Cr-labelled eosinophils through human airway epithelial cell layers from the basal to mucosal side. These effects were completely abolished by a mixture of a monoclonal antibody regulated on activation, normal T cells expressed and secreted (RANTES) and an antibody to granulocyte macrophage-colony stimulating factor (GM-CSF). CONCLUSION: These results suggest that human respiratory SMG cells may augment eosinophil transmigration across the airway epithelium through the secretion of RANTES and GM-CSF after RV infection, and may contribute to exacerbations of asthma.

Chemokines in eosinophil-associated gastrointestinal disorders.

Eosinophil-associated gastrointestinal disorders (EGDs) are characterized by a pronounced cellular inflammation. Recent clinical and experimental investigations have implicated a family of molecules known as chemokines in the regulation of leukocyte recruitment in these diseases. The underlying cellular and molecular mechanisms involved in chemokine-mediated cellular infiltration are largely unknown. In this review, we describe the role of CD4+ T cells and eosinophils in the clinical manifestations of EGDs and discuss the current understanding of the role of chemokines in the recruitment of these cells in the expression of diseases.

The role of CCL22 (MDC) for the recruitment of eosinophils during allergic pleurisy in mice.

Eosinophils are important inflammatory cells in allergic diseases. In the present study, we have investigated the effects of CCL22 on the recruitment of eosinophils in vivo and in vitro. CCL22 induced a dose- and time-dependent recruitment of eosinophils into the pleural cavity of mice, and this was dependent on the release of platelet-activating factor (PAF) and subsequent generation of CCL11. However, in an allergic pleurisy model, an anti-CCL22 polyclonal antibody given during sensitization or before challenge had no significant effect on eosinophil recruitment. CCL22 did not induce eosinophil chemotaxis in vitro but was able to induce eosinophil degranulation in vitro and in vivo. In conclusion, we show that although exogenously added CCL22 may induce eosinophil migration in vivo via release of PAF and CCL11 (eotaxin), endogenous production of CCL22 does not drive eosinophil migration during allergic inflammation. However, CCL22 may be an important activator of eosinophils once these cells have migrated into tissue.

Eosinophilic gastroenteritis: a problem of the mucosal immune system?

The gastrointestinal immune system is a major component of the mucosal barrier, which provides an appropriate immunologic homeostasis between host and numerous foreign antigens, including microbial and dietary antigens. However, under certain pathological circumstances created by disturbance of the immunologic balance, allergic responses associated with the gastrointestinal tract can be triggered by abnormal immune responses against selected food protein antigens. Among the several types of immune competent cells, eosinophils are generally considered to play a central role for the development of allergic diseases in gastrointestinal tissue. Although most research has been focused on the molecular and cellular understanding of eosinophils in the peripheral tissues and lung, recent studies elucidate the unique trafficking and regulation mechanisms of eosinophils in the gastrointestinal tissues. In this review, we summarize current findings in the regulatory mechanism of gastrointestinal eosinophils. Furthermore, several unique murine models for eosinophilic gastroenteritis, which can be applied for the elucidation of underlying mechanisms of eosinophil-mediated gastrointestinal allergy, and the development of new mucosal immune therapy for the control of food allergy are reviewed.

Synergistic enhancement of antitumor immunity with adoptively transferred tumor-specific CD4+ and CD8+ T cells and intratumoral lymphotactin transgene expression.

The lack of efficient T-cell infiltration of tumors is a major obstacle to successful adoptive T-cell therapy. We have shown that transplanted SP2/0 myeloma tumors that have been engineered to express lymphotactin (Lptn) invariably regress under the influence of infiltrating XCR1+T cells and neutrophils. Herein, we characterize these T cells and investigate their therapeutic efficacy, either alone or with Lptn gene therapy. After stimulation with SP2/0 cells, these T cells were CD25+FasL+L-selectin-, expressed XCR-1, and were chemoattracted by Lptn in vitro. They comprised 66% CD4+ Th1 and 33% CD8+ Tc1 cells, both of which expressed significant amounts of IFN-gamma, perforin, and tumor necrosis factor-alpha, but not interleukin-4. The CD4+ Th1 and CD8+ Tc1 cells, which were inhibited and stimulated, respectively, for proliferation with Lptn signaling, displayed 38 and 84% specific killing, respectively, for Ia(d)/H-2K(d)-expressing SP2/0 tumor cells (E:T ratio, 100). In vivo, combined intratumoral Lptn gene transfer and adoptive immunotherapy with these CD4+ and CD8+ T cells eradicated well-established SP2/0 tumors in six of eight mice, and dramatically slowed tumor growth in the other two mice. Cell tracking using labeled T cells confirmed that these cells infiltrated better into the Lptn-expressing tumors than non-Lptn-expressing ones. Control or Lptn adenoviral treatments by themselves did not alter the lethal outcome for tumor-bearing mice, nor did T-cell therapy by itself, although the latter two treatments did slow its time frame. Combined Lptn gene transfer and adoptive CD4+ or CD8+ cell transfers were not nearly as efficacious as the combined Lptn gene and unfractionated T-cell transfers. Taken together, our data provide solid evidence of a potent synergy between adoptive CD4+ and CD8+ T-cell therapy and Lptn gene transfer into tumor tissues, which culminated in the eradication of well-established tumor masses.

Eotaxin represents the principal eosinophil chemoattractant in a novel murine asthma model induced by house dust containing cockroach allergens.

Asthma represents a serious health problem particularly for inner city children, and recent studies have identified that cockroach allergens trigger many of these asthmatic attacks. This study tested the concept that asthma-like pulmonary inflammation may be induced by house dust containing cockroach allergens. An aqueous extract was prepared from a house dust sample containing endotoxin and high levels of cockroach allergens. BALB/c mice were immunized with the house dust extract (HDE) and received two additional pulmonary challenges. Bronchoalveolar lavage (BAL) eosinophil counts and eotaxin levels were significantly increased in immunized mice exposed to the HDE, whereas neutrophils were the predominant BAL inflammatory cell in the unimmunized mice. Kinetics studies in immunized mice demonstrated a peak pulmonary inflammatory response 48 h after the last challenge. The allergic response in this model was further confirmed by histological and physiological studies demonstrating a significant influx of eosinophils and lymphocytes in the peribronchial area, and severe airway hyperreactivity through whole-body plethysmography. The specificity of the response was established by immunizing with HDE and challenging with purified cockroach allergen, which induced pulmonary eosinophilia and airway hyperreactivity. Ab inhibition of eotaxin significantly inhibited the number of BAL eosinophils. These data describe a novel murine model of asthma-like pulmonary inflammation induced by house dust containing endotoxin and cockroach allergens and further demonstrate that eotaxin represents the principal chemoattractant for the recruitment of the pulmonary eosinophils.