Human nasal polyp epithelial basophil/mast cell and eosinophil colony-stimulating activity. The effect is T-cell-dependent

The Microenvironmental Differentiation Hypothesis of Airway Inflammation

We have observed clinically relevant increases and fluctuations in metachromatic cell and eosinophil progenitors in response to antigenic challenge in patients with upper and lower respiratory tract disease. Based on this we have developed in vitro models to assess cytokine and microenvironmental influences on nasal mucosal inflammation. Purified structural cells (nasal epithelial cells or fibroblasts) grown from nasal polyps and atopic or nonatopic inferior turbinate secrete known (GM-CSF, G-CSF, and IL-6) and possibly novel (basophil differentiation factor) hemopoietic cytokines capable of inducing neutrophil, monocyte-macrophage, eosinophil, and metachromatic cell differentiation, as well as influencing their activation and survival. Nasal polyp structural cells are phenotypically different from those derived from allergic rhinitis or normal control subjects, having increased proliferative potential and constitutively producing higher levels of cytokines and extracellular matrices capable of supporting cell growth. These studies emphasize the importance of microenvironmental influences on allergic and nonallergic airway inflammation, and point out potentially new approaches to the diagnosis and therapy of nasal polyposis, allergic rhinitis, and asthma.

Hemopoietic progenitors: the role of eosinophil/basophil progenitors in allergic airway inflammation

Progenitor cells play important roles in the physiology and homeostasis of the overall hemopoietic system. The majority of hemopoietic activity takes place in the bone marrow, under the influence of resident marrow stromal cells, accessory cells, and/or their products. This constitutes the complex network of the hemopoietic inductive microenvironment, which is crucial for providing signals necessary for the maintenance of populations of progenitors at varying stages of lineage commitment. Accumulation of eosinophils and basophils in tissues is characteristic of allergic inflammation. A large body of evidence now exists which confirms that these tissue inflammatory events are coincident with relevant changes in progenitors; it has thus been hypothesized that the observed changes in mature cell numbers occur directly or indirectly as a result of differentiation of lineage-committed eosinophil/basophil, and perhaps other, progenitor cells. Differentiation and maturation of hemopoietic cells have traditionally been thought to be restricted to the bone marrow microenvironment. More recently, evidence has accumulated to suggest that some hemopoietic cells present in allergic tissue may be recruited from the bone marrow, traffic through the peripheral circulation and into tissues to participate in the ongoing inflammatory process at these distal sites. The clinical administration of monotherapy with topical corticosteroids, oral cysteinyl leukotriene antagonists and cytokine antagonists such as antibodies to interleukin-5, suggest that suppression of hemopoietic contributions to allergic inflammation may be necessary for full control of allergic inflammation and disease manifestations. In addition to progenitors being targets of therapy, they may well determine how and whether allergic inflammation is generated in early life, thus serving as biomarkers of disease.

Alteration of mitochondrial DNA sequence and copy number in nasal polyp tissue

This study was designed to investigate the possibility that mtDNA mutations might arise in inflammatory or chronically damaged nasal polyp tissue from 23 patients. Thirteen patients (57%) displayed nasal polyp tissue-specific mtDNA mutations in the hypervariable segment of the control region and cytochrome b gene, which were not found in the corresponding blood cells and/or adjacent normal tissue. Nasal polyp tissue-specific length heteroplasmic mutations were also detected in nucleotide position (np) 303-315 homopolymeric poly C track (39%), np 514-523 CA repeats (17%) and np 16184-16193 poly C track (30%). The average mtDNA copy number was about three times higher in nasal polyp tissue than in the corresponding peripheral blood cells and adjacent non-polyp tissues. The level of reactive oxygen species (ROS) was significantly higher in the nasal polyp tissues compared to those from the corresponding samples. High level of ROS in nasal polyp tissue may contribute to development of mtDNA mutations, which may play a crucial role in the vicious cycle of pathophysiology of nasal polyps.

Distinct phenotypic adhesion molecule expression on human cord blood progenitors during early Eosinophilic commitment: upregulation of beta(7) integrins

Increasing levels of proinflammatory cells, including eosinophils and basophils, are seen at the site of allergen challenge in allergic disease of the airways. Mechanisms for the recruitment of these cell types could involve either specific upregulation of adhesion molecule and chemoattraction, or the initiation of proliferation and differentiation of inflammatory cell progenitors derived from the bone marrow. In this study, we demonstrate, in two systems of eosinophilic-basophilic lineage-committed granulocytes of relative immaturity, that eosinophilic differentiation in vivo implies the induction of a distinct adhesion phenotype, characterized by the upregulation of beta(7) integrin and downregulation of beta(1) and alpha(5) integrins. Moreover, the eosinophilic differentiation induced an upregulation of complement receptor type 1 and type 3, and the expression was further enhanced upon a short-course in vitro activation with ionomycin. These data indicate a sequential alteration of disparate members of the integrin family during eosinophilic-basophilic differentiation, which may attribute to specific adhesion requirements at distinct stages of cell maturation.

Expression of glucocorticoid receptors and cyclooxygenase-2 in nasal polyps from nonallergic patients

Glucocorticoid treatment has been widely used to suppress inflammatory and immune responses. However, from a clinical point of view, its efficacy in the treatment of nasal polyposis seems to vary individually from patient to patient. In the present study, we examined the presence of glucocorticoid receptors (GRs) and cyclooxygenase-2 (COX-2) in the nasal polyps of nonallergic patients as compared with normal controls. Reverse transcription-polymerase chain reaction analyses revealed the presence of both GR messenger RNA and COX-2 messenger RNA expression in nasal polyps from nonallergic patients, as well as in normal nasal mucosa from controls. Consistent with this finding, immunohistochemical analysis demonstrated that GRs and COX-2 were labeled in both tissues. In nasal polyps, GR labeling was associated with the cytoplasm and nucleus of surface mucosa, submucosal glands, endothelial cells, and inflammatory cells. Importantly, COX-2 labeling was seen in the cytoplasm of surface mucosa, submucosal glands, and the vascular wall in nasal polyps. In contrast, in normal nasal tissues, COX-2 labeling was only found in the vascular wall, and the expression was weaker--a finding demonstrating that COX-2 is upregulated in nasal polyps. Therefore, 1) the presence of GRs and COX-2 in nasal polyps from nonallergic patients, as well as upregulation of COX-2 expression, suggests that inflammation may play an important role in the pathophysiology of nasal polyps; and 2) glucocorticoid could be a potential treatment method for suppressing inflammatory processes.

The effects of inhaled budesonide on circulating eosinophil progenitors and their expression of cytokines after allergen challenge in subjects with atopic asthma

Allergen inhalation by dual responder subjects with atopic asthma is associated with an increase in circulating eosinophil/basophil colony-forming units (Eo/B CFU) and granulocyte-macrophage colony- stimulating factor (GM-CSF) immunolocalization in Eo/B colony cells grown in vitro. The current study examined the effect of the inhaled corticosteroid, budesonide, on the number of allergen- induced circulating eosinophils and Eo/B CFU, and immunolocalization of GM-CSF and interleukin-5 (IL-5) in Eo/B colony cells grown in vitro. Sixteen subjects with mild atopic asthma were treated for either 7 or 8 d with 200 microg inhaled budesonide or placebo twice a day. Peripheral blood was collected before and 24 h after allergen inhalation challenge and nonadherent mononuclear cells (NAMC) were grown in methylcellulose culture. Eo/B CFU were enumerated after 14 d in culture, and prepared on slides for immunocytochemistry. Budesonide attenuated the allergen-induced increase in circulating eosinophils (4.0 +/- 0.4 x 10(5)/ml versus 6.5 +/- 0.7 x 10(5)/ml, p = 0.0001), circulating Eo/B CFU (12.4 +/- 2.3/10(6) NAMC versus 18.8 +/- 4.6/10(6) NAMC, p = 0.05), and immunolocalization of GM-CSF in Eo/B colony cells (11.8 +/- 1.9% positive versus 18.0 +/- 2.2%, p = 0.01) but not immunolocalization of IL-5 (7.9 +/- 1.4% versus 4.5 +/- 0.6%, p > 0.05). Inhaled budesonide attenuated the number of allergen-induced circulating eosinophils and their progenitors grown in the presence of GM-CSF, which may partially be a result of regulating eosinophil progenitor expression of the autocrine growth factor GM-CSF.

Systemic aspects of allergic disease: bone marrow responses

In patients with allergic diseases, allergen provocation can activate a systemic response that provokes inflammatory cell production by the bone marrow. After release and differentiation of progenitor cells, eosinophils, basophils, and mast cells are typically recruited to tissues in atopic individuals. An understanding at the molecular level of the signaling process that leads to these systemic responses between the target organ, especially the airways, and the bone marrow may open up new avenues of therapy for allergic inflammatory disease. Studies that support the critical involvement of the bone marrow in the development of eosinophilic inflammation of the airways point out the systemic nature of these conditions and their potential for biologic intervention. Hemopoietic events that originate in the bone marrow are potential targets of long-term therapy for rhinitis and asthma. For example, the "beneficial" systemic activity of cortico-steroids through modulation of hemopoietic mechanisms and inflammatory cell recruitment to the airways is essential for the optimal treatment of both upper and lower airway inflammation.

Selective upregulation of a functional beta7 integrin on differentiating eosinophils

BACKGROUND

The sequence of adhesion-molecule expression during eosinophil differentiation remains unclear.

METHODS

We analyzed the surface expression of alpha4, beta1, and beta7 integrins and compared it to established myeloid developmental markers, using the eosinophilic cell line HL-60 clone 15, as well as cord and peripheral blood differentiation assays.

RESULTS

Cells induced to eosinophil differentiation by treatment with butyric acid, IL-5, and GM-CSF showed a significant upregulation of beta7 integrin expression coincident with a marked upregulation of CD35 and attenuation of CD33 and beta1 integrin expression. In addition, adhesion of induced HL-60 clone 15 cells to fibronectin was attenuated by a beta7 integrin antibody.

CONCLUSIONS

Our data show that protein synthesis-dependent upregulation of the functional beta7 integrin occurs under conditions when beta4 and beta1 integrins are fully expressed, indicating a sequential appearance of specific adhesion molecules on differentiating eosinophil progenitors.

Lactoferrin and eosinophilic cationic protein in nasal secretions of patients with experimental rhinovirus colds, natural colds, and presumed acute community-acquired bacterial sinusitis

To distinguish sinusitis from uncomplicated "colds," we examined lactoferrin and eosinophilic cationic protein (ECP) in nasal secretions. Lactoferrin titers were >/=1:400 in 4% of persons with uncomplicated colds and controls but in 79% of persons with sinusitis or purulent sputa. ECP levels were >200 ng/ml in 61% of persons with colds and >3,000 ng/ml in 62% of persons with sinusitis. Nasal lactoferrin helps distinguish sinusitis from colds.

Quantitative analysis of eotaxin and RANTES messenger RNA in nasal polyps: association of tissue and nasal eosinophils

OBJECTIVES/HYPOTHESIS

Nasal polyps develop in the ethmoidal and middle turbinate area, often in relation to inflammatory conditions. Their exact etiology and pathogenesis are still under debate. Histologically, the polyps are infiltrated by a number of inflammatory cells, with eosinophil predominating in most specimens. This finding suggests that the nasal polyp is an inflammatory growth that is controlled by the local environment. The chemokines eotaxin and RANTES (regulated on activation normal T cell expressed and secreted) have been postulated to be involved in the recruitment and activation of eosinophils to certain inflamed tissues. The purpose of this study was to investigate eotaxin and RANTES mRNA expression in nasal polyps and its effect on tissue and nasal eosinophils.

METHODS

Nasal polyps (917 allergic and 30 nonallergic cases) were obtained from endoscopic sinus surgery, and 15 normal inferior turbinates also were taken. Immunohistochemical staining for eosinophils and quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) tests for eotaxin and RANTES mRNA expression were performed, and the concentration of nasal eosinophil cationic protein (ECP) was measured.

RESULTS

The amounts of eotaxin mRNA in the allergic nasal polyps were 11.4 times higher and the levels in the nonallergic polyps were 6.4 times higher than in the normal inferior turbinate. However, the RANTES mRNA expression did not show any differences among the three groups. Tissue eosinophilia and nasal ECP levels were significantly correlated with eotaxin mRNA level but not with RANTES mRNA expression.

CONCLUSION

Nasal polyp eosinophilic infiltration and activation correlate mainly with increased eotaxin gene expression rather than with RANTES expression.

IL-5 production by bone marrow stromal cells: implications for eosinophilia associated with asthma

BACKGROUND

Eosinophil infiltration of bronchial tissue is a hallmark of asthma. Recruitment of eosinophils into pulmonary tissue is dependent on the presence of IL-5. In addition, IL-5 plays a significant role in the differentiation, proliferation, and maturation of eosinophil progenitor cells in the bone marrow before recruitment into the lung. The contribution of bone marrow eosinophil production to eosinophilia associated with asthma is poorly understood.

OBJECTIVE

The aims of this study were to determine whether bone marrow stromal cells produce IL-5 and to determine whether IL-5 production by stromal cells is upregulated by IL-1, an inflammatory cytokine associated with asthma.

METHODS

IL-5 messenger (m)RNA from bone marrow stromal cells was amplified by RT-PCR and sequenced. Stromal cells were lysed, and IL-5 protein production was measured by ELISA. Upregulation of stromal cell IL-5 transcription, translation, and functional effect on eosinophil differentiation was evaluated after stimulation with recombinant IL-1alpha and IL-1beta and compared with untreated cells.

RESULTS

Bone marrow stromal cells transcribe and translate IL-5. The nucleotide sequence of IL-5 mRNA from stromal cells was identical to that previously reported for murine T cells. IL-5 mRNA abundance in stromal cells increased with increasing cell confluence in culture. IL-5 mRNA and protein levels were upregulated by exposure of stromal cells to the inflammatory cytokines IL-1alpha and IL-1beta. Exposure of stromal cells to IL-1 resulted in increased eosinophil differentiation in coculture experiments with nonadherent bone marrow cells.

CONCLUSION

The production of IL-5 mRNA and protein by bone marrow stromal cells is a novel finding that has implications for both normal eosinophilopoiesis and development of the accelerated eosinophil production associated with asthma.

GM-CSF, IL-5 and RANTES immunoreactivity and mRNA expression in chronic hyperplastic sinusitis with nasal polyposis (NP)

BACKGROUND

Eosinophils are a prominent feature of chronic hyperplastic sinusitis with nasal polyposis (CHS/NP). Our previous studies showed that their presence was associated with the expression of GM-CSF and RANTES mRNA. In allergic NP, increased expression of IL-5 was also found.

OBJECTIVE

We wished to examine cytokine immunoreactivity for IL-5, GM-CSF and RANTES mRNA in allergic and non-allergic NP and compare immunoreactivity with expression of cytokine mRNA by in situ hybridization. Methods NP were obtained from five allergic and eight non-allergic subjects with CHS/ NP. Middle turbinate tissue from eight normal subjects were used as controls. Cell-associated cytokine mRNA was detected by in situ hybridization (ISH). Cytokine immunoreactive cells were enumerated by immunostaining. Colocalization immunostaining was also performed to identify specific cell types producing IL-5.

RESULTS

Immunostaining for GM-CSF, IL-5 and RANTES protein was increased in both allergic and non-allergic NP compared with control middle turbinates. Allergic polyps contained greater numbers of IL-5 immunoreactive cells (P = 0.01), whereas non-allergic polyps contained greater numbers of GM-CSF immunoreactive cells (P = 0.04). Immunostaining was primarily associated with inflammatory cells, but immunostaining for RANTES and, to a lesser extent GM-CSF, was also seen in the epithelium. The density of immunoreactive cells was variably correlated with cytokine mRNA+ cells (GM-CSF: R=0.56, P=0.05; IL-5: R=0.76, P=0.003; and RANTES: R=0.89, P=0.0005). Colocalization immunostaining revealed that the majority of IL-5 immunoreactive cells in both allergic and non-allergic NP were T lymphocytes. However, allergic NP contained greater numbers of IL-5+/CD3+ T lymphocytes and IL-5+ mast cells, whereas non-allergic NP contained greater numbers of IL-5+ eosinophils.

CONCLUSION

We conclude that GM-CSF, IL-5 and RANTES are produced in increased amounts in both allergic and non-allergic NP. Distinguishing features of non-allergic NP include fewer numbers of CD3 T lymphocytes, fewer IL-5+/CD3+ T lymphocytes and greater numbers of IL-5+ eosinophils. These differences may suggest different mechanisms of eosinophil accumulation and activation in allergic vs non-allergic NP.

Enhanced expression of GM-CSF in differentiating eosinophils of atopic and atopic asthmatic subjects

Higher numbers of eosinophil/basophil colony-forming units (Eo/B CFU) are observed in blood of atopic individuals, and can be enhanced in atopic asthmatics by allergen-inhalation challenge. It is known that mature basophils and eosinophils synthesize cytokines relevant to allergic inflammation. To investigate the potential role of growth factors in allergic disease we examined the expression of the hemopoietic cytokines, granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-5, in differentiating Eo/B colony cells from normal and atopic individuals, and from atopic asthmatics before and after allergen-inhalation challenge. Peripheral blood was collected from two normal and 12 atopic individuals, and also from 25 atopic asthmatics before and 24 h after allergen challenge. Nonadherent mononuclear cells were isolated and grown in semisolid growth medium. Eo/B colonies were selected and cytospins were prepared for immunocytochemical analysis of colony cells. Eo/B colonies, especially carbol chromotrope 2R+ cells, selected at Days 10, 14, and 18 from atopic donors contained messenger RNA for GM-CSF by combined in situ reverse transcription-polymerase chain reaction and cytochemistry, and demonstrated time-dependent expression of GM-CSF by immunocytochemistry (P = 0.007). Atopic individuals demonstrated a higher percentage of cells expressing GM-CSF than did normal subjects under all growth conditions when examined at Day 14 (P = 0. 04). Atopic asthmatics challenged with inhaled allergen who demonstrated a dual airway response, an increase in the number of blood eosinophils (P = 0.0001), and an increase in the number of Eo/B CFU (P = 0.02) also demonstrated a significant increase in the percentage of colony cells expressing immunostainable GM-CSF (P = 0. 0009), but only a variable effect on those expressing IL-5, 24 h after allergen. These results suggest that GM-CSF expression by differentiating Eo/Bs may provide an additional stimulus in vivo to enhance Eo/B progenitor differentiation in atopic and asthmatic individuals, especially after allergen challenge. The concept of microenvironmental differentiation, where blood progenitor cells may aid in their own differentiation, is supported by these ex vivo findings.

Nasal polyps and their relation to polyps/hypertrophic polypoid mucosa in the paranasal sinuses: a macro-, endo-, and microscopic study of autopsy materials

The present study comprised macro- and endoscopic screening of the nasosinusal complex in 56 autopsies, 24 with nasal polyps and 32 without. Seven had nasal polyposis (bilaterally more than two). Hypertrophic polypoid mucosa in the paranasal sinuses was not found in the cases with nasal polyposis and in only 2 (4%) of the total number (24) of cases with polyps. Microscopic examination of nine small polyps, the mucosa from which they originated, and control specimens showed accumulation of eosinophils in the mucosa from which the polyps originated, indicating localized inflammation.

Eosinophil expression of transforming growth factor-beta and its receptors in nasal polyposis: role of the cytokines in this disease process

PURPOSE

Nasal polyposis (NP) is characterized by an increase in inflammatory processes including fibrosis. Because transforming growth factor beta (TGF-beta) has been proven to induce fibrosis, we hypothesize that TGF-beta and its receptors are present in NP and influence polyp development.

MATERIALS AND METHODS

To test this hypothesis, we evaluated distribution (immunohistochemistry) of TGF-beta isoforms (TGF-beta 1, TGF-beta 2, and TGF-beta 3) and its receptors [(TGF-beta(RI) & TGF-beta(RII)] in NP from 36 NP patients and in five normal sinus tissue specimens obtained from septoplasty/inferior turbinectomy. Tissue levels of TGF-beta 1 and TGF-beta 2 levels were determined by enzyme-linked immunosorbent assay (ELISA) and protein content was determined by Bio Rad assay (Bio Rad, Richmond, CA). All tissue levels of TGF-beta were normalized and expressed as pg of TGF-beta per mg of total protein (pg/mg TP).

RESULTS

Immunohistochemical studies showed eosinophils as the major cells positively staining for TGF-beta 1, TGF-beta 2, TGF-beta 3, TGF-beta(RI), and TGF-beta. In fibrotic sections, increased staining of eosinophils, fibroblast, and mononuclear cells was found for all three isoforms and both receptors. Evaluation of tissue levels indicated mean levels of TGF-beta 1 in the NP were 11.64 +/- 22.12 pg/mg TP versus normal control mean 44.36 +/- 22.12 pg/mg TP.TGF-beta 2 mean levels were 11.46 +/- 23.73 pg/mg TP versus normal control mean of 2.03 +/- 1.13 pg/mg TP. NP showed decreased expression of TGF-beta 1 and enhanced expression of TGF-beta 2 isoforms with presence of their receptors. Higher levels of TGF-beta 2 correlated with an increase in previous polypectomies perhaps indicative of severity of disease (P < or = .0001).

CONCLUSION

Our studies show the presence of the TGF-beta isoforms and receptors in NP tissue. The results support our hypothesis that the eosinophil continues to be a pivotal inflammatory cell in NP, a differential regulation may govern the activity of TGF-beta in NP, and hence, the TGF-beta family of cytokines and receptors likely play a key role in controlling NP formation.

Stem cell factor in nasal polyposis and allergic rhinitis: increased expression by structural cells is suppressed by in vivo topical corticosteroids

BACKGROUND

Mast cells are increased in nasal polyp (Np) and allergic rhinitis (AR) tissue and are suppressed by topical corticosteroid treatment. Stem cell factor (SCF), a mast cell growth and survival factor, may explain these phenomena.

OBJECTIVE

We investigated structural cell gene expression and production of SCF in nasal tissues in patients who had received and who had not received in vivo intranasal corticosteroid therapy.

METHODS

Northern blot analyses for messenger RNA and ELISA for biologically active SCF protein from cultured Np epithelial cells and fibroblasts were performed. Immunostaining for SCF in cultured and tissue nasal structural cells in the presence or absence of steroid treatment was also performed.

RESULTS

We detected significant expression of SCF mRNA and protein by cultured Np epithelial cells and Np fibroblasts; Np fibroblast SCF supported the differentiation of mast cells in vitro. There were more immunoreactive SCF-positive Np epithelial cells in patients with AR than in control subjects (97.2 +/- 2.8 vs 45.6 +/- 22.0%; p < 0.0001). SCF that could be immunostained was significantly diminished overall in Np structural cells in the group given in vivo steroid treatment, with a modest (trend to significant) effect on any given cell type analyzed. In vitro treatment with budesonide of SCF-producing fibroblasts demonstrated inhibition of unstimulated, primary Np fibroblasts but not of IL-1-stimulated fibroblasts or transformed cell lines.

CONCLUSIONS

Human Np and AR tissue structural cells express and produce increased SCF. Our in vitro studies suggest that intranasal steroids blunt SCF expression in Nps, an effect that may be responsible for a decrease in mast cells and symptoms.

Interleukin-3 interleukin-5, and granulocyte-macrophage colony-stimulating factor expression in nasal polyps

PURPOSE

Nasal polyps (NP) are grape-like clusters of chronically inflamed tissue. Little is known about the underlying cells and cytokines involved in nasal polyposis. For the present study, we hypothesize that elevated tissue levels of interleukin-3 (IL-3), interleukin-5 (IL-5), and granulocyte-macrophage colony-stimulation factor (GM-CSF) contribute to eosinophil recruitment and activation in NP.

MATERIALS AND METHODS

To begin to test this hypothesis, we evaluated IL-3, IL-5, and GM-CSF levels and distributions in nasal polyp specimens obtained intraoperatively from 13 patients and two normal controls. For these studies, nasal polyp levels were determined by enzyme-linked immunosorbent assay (ELISA), and IL-3, IL-5, and GM-CSF distribution was determined by immunohistochemistry.

RESULTS

Immunohistochemical staining of the NP indicated that in all 13 patient samples, IL-3, IL-5, and GM-CSF were associated with infiltrating cells, primarily eosinophils, in the NP. Quantitation of IL-3, IL-5, and GM-CSF in NP tissue homogenates indicated that IL-3, IL-5, and GM-CSF levels were evaluated in the NP tissues when compared with control tissues. Additionally, elevation of individual cytokines correlated with previous polypectomy (IL-3), steroid use (IL-3, IL-5, and GM-CSF), asthma (IL-5), and age (GM-CSF).

CONCLUSION

These data support our hypothesis that IL-3, IL-5, and GM-CSF are likely to play a key role in eosinophil recruitment/activation and NP formation and support recently advanced theories that cytokines play a key role in the pathogenesis of this disease.

Distribution of mast cells and eosinophils in nasal polyps from atopic and nonatopic subjects: a morphometric study

The pathogenetic mechanism of nasal polyps remains unknown, although polyps seem to be an expression of chronic nasal inflammation of both allergic and nonallergic origin. The goal of our study was to compare the distribution mast cells and eosinophils (cells traditionally associated with allergic inflammation) in nasal polyps from well defined atopic and nonatopic patients, using advanced morphometric analysis system. Nasal polyps were removed during routine nasal polypectomy performed in 17 atopic and 19 nonatopic patients. Parafin sections of nasal polyps were stained with haematoxilin/eosin, chromotrope R2 or toluidine blue, and light microscopy, assisted with computerized picture analysis system, was used to count the number of cells in the superficial and stromal layer of the mucosa. Regardless of the presence or absence of atopy, eosinophils were predominant cells in the polyps, and both eosinophils and mast cells were more abundant in the superficial layer than in the stromal layer of the mucosa. The density of eosinophils in both layers and mast cells in the stromal layer was similar in atopic and nonatopic patients. Only the density of mast cells in the superficial layer of the mucosa was slightly higher (p < 0.005 in atopic compared to nonatopic patients): In both groups of patients a significant correlation between the number of mast cells and eosinophils in the superficial layer of the polyp mucosa was found (r = 0.84; p < 0.001). Our study demonstrates that eosinophils and mast cells are abundant in nasal polyps from both atopic and nonatopic patients and that mast cells seem to be more superficially distributed in atopic compared to nonatopic patients.

Electron microscopic and immunomorphological investigations on the mucosa of the human paranasal sinuses

The morphology of the mucosa from the human paranasal sinuses was investigated by electron microscopy. A total of 27 specimens was taken from 11 patients following midfacial fractures. All tissue samples were biopsied during surgery after informed consent had been given. In accordance with light microscopic investigations, the mucosa represented a highly prismatic epithelium consisting of kinocilia-carrying and mucus-producing (goblet) cells. Other cell types, such as those occurring in the respiratory epithelium of other areas, could not be demonstrated. Electron microscopic and immunomorphological investigations revealed collagen type VII beneath the lamina densa of the basal lamina. According to findings obtained to date, this collagen type accompanies only a multilayered epithelium. Another peculiarity was the small number of basophils and eosinophils. Pronounced acute reactions of the mucosa in this area cannot be expected, which is in contrast to that of the nasal mucosa.

Eosinophils in the pathophysiology of nasal polyposis

Nasal polyposis can be defined as a chronic inflammatory disease of the paranasal sinus mucosa, leading to a protrusion of benign edematous polyps from the meatus into the nasal cavities. Nasal polyps are histologically characterized by massive edema and accumulation of eosinophils. IgE-mediated allergy seems to play only a minor role in eosinophil accumulation, leaving the place for a new concept of non-allergic rhinitis with eosinophilia. The central question still remains, however, why eosinophils accumulate into nasal polyposis tissue. Some initial data show that tissue structural cells, i.e. epithelial cells or fibroblasts, could produce cytokines (GM-CSF) and play a role in eosinophil accumulation (micro-environmental theory). However, further studies showed, that GM-CSF was mainly produced by eosinophils themselves (autocrine theory), leading to the hypothesis of an intrinsic eosinophilic inflammatory process. Eosinophils may contribute to nasal polyp formation and growth not only through inflammation but also by exerting their effects on extracellular matrix including stimulation of collagen synthesis. Another feature associated with nasal polyposis is aspirin sensitivity. Some preliminary data indicate that eosinophils could also be involved in aspirin-sensitivity mechanisms.

Role of Allergy in Nasal Polyposis: A Review

We propose a multivariate theory for the pathogenesis of nasal polyps. Turbulent flow of air in the lateral wall of the nose or viral-bacterial-host interactions produce an inflammatory change in the mucosa of the lateral wall of the nose. Ulceration and prolapse of the submucosa with reepithelialization and new gland formation may then follow. The structural cells of the nasal polyp, including epithelial cells and fibroblasts, have the ability to produce messenger RNA for granulocyte-monocyte colony-stimulating factor and other cytokines. Stimulation of such an effector capability by structural cell-derived cytokines would undoubtedly represent a major amplification pathway of the inflammatory response in nasal polyps. Allergy may be one mechanism for the development of this cascade of events. This microenvironmental structural inflammatory response in the nasal polyp, in turn, can affect the bioelectric integrity of the Na+ and Cl− channels at the luminal surface of the respiratory epithelial cell. The change in the Na+ absorption, which has been demonstrated in our studies, may result in an increased movement of water into the cell and into the interstitial fluid. The resultant edema can lead to growth and enlargement of the nasal polyp. Finally, the rapid recurrence of nasal polyps despite adequate surgery may reflect some intrinsic phenotypic characteristic of nasal epithelial cells in the lateral wall of the nose, which is likely to be under genetic control.

Immunopharmacology of asthma

Acute symptoms of asthma are largely a consequence of contraction of airway smooth muscle, yet emphasis in asthma pharmacology has shifted away from smooth muscle dysfunction and refocussed upon inflammatory events in the airway mucosa and submucosa. Thus, as described by John Morley existing anti-asthma drugs are used either to suppress inflammatory events (as preventive therapy), or to relieve obstruction to airflow (as symptomatic therapy). There is now a prospect of novel drugs that, by inhibiting phosphodiesterase isoenzymes selectively, will combine preventive and symptomatic therapies within a single molecule. Since atopy is associated with aberrant expression of phosphodiesterase isoenzymes in mononuclear cells, such therapies may belie their pragmatic origins and be envisaged as targeting a specific molecular defect.

Immunopharmacology of asthma

Acute symptoms of asthma are largely a consequence of contraction of airway smooth muscle, yet emphasis in asthma pharmacology has shifted away from smooth muscle dysfunction and refocussed upon inflammatory events in the airway mucosa and submucosa. Thus, as described by John Morley, existing anti-asthma drugs are used either to suppress inflammatory events (as preventive therapy), or to relieve obstruction to airflow (as symptomatic therapy). There is now a prospect of novel drugs that, by inhibiting phosphodiesterase isoenzymes selectively, will combine preventive and symptomatic therapies within a single molecule. Since atopy is associated with aberrant expression of phosphodiesterase isoenzymes in mononuclear cells, such therapies may belie their pragmatic origins and be envisaged as targeting a specific molecular defect.

Histochemical and immunohistochemical characteristics of mast cells in nasal polyps

In surgically excised nasal polyps, most epithelial mast cells were formalin sensitive, chloroacetate esterase (CAE) negative, and chymase negative. Thus, this represents a population of mast cells not identified by staining for CAE. On the other hand, most stromal mast cells were formalin resistant and CAE positive, and although there was some polyp-to-polyp variability in their content of neutral protease, most of these cells were positive for both tryptase and chymase. The percentage of metachromatic cells in the epithelium and the number of metachromatic cells per unit area of polyp tissue did not correlate with an index of allergy skin test reactivity or the serum IgE concentration. The percentage of mast cells surrounded by pericellular tryptase, suggesting activation/degranulation, was significantly higher in the stroma than in the epithelium. The findings demonstrate differences between the stroma and the epithelium in phenotype and state of activation of mast cells; these are postulated to be due to distinct microenvironmental factors that affect mast cells at these sites.

Eosinophils: a review

The eosinophil was discovered by Jones in 1846 (Dessein and David, 1982) but its proclivity to stain with aniline dyes was first described by Paul Ehrlich in 1879 (Hirsch and Hirsch, 1980). Recognized and named for this quality, eosinophils possess an abundance of highly basic proteins within their granules which confer their affinity for acidic dyes (Gleich and Loegering, 1984). Eosinophils are traditionally viewed as killer-effector cells in parasitic infestations and as modulators of Type I hypersensitivity reactions (Butterworth and David, 1981; Kay, 1985). The eosinophils' reserve of cationic proteins and enzymes which imparts their profound parasiticidal effects (Butterworth and David, 1981) contrasts with this leukocyte's purported regulatory function in inflammation (Kay, 1985; Fechter et al., 1986). The opposing functions possessed by this leukocyte exemplify the enigma of the eosinophil. Recent evidence suggests that although the eosinophil does posses some regulatory capabilities, its presence is, in fact, a harbinger of tissue destruction (Gleich and Adolphoson, 1986, Wardlaw and Kay, 1987; Spry, 1988). Nor does the presence of the eosinophil automatically infer IgE mediated hypersensitivity, as evidenced by studies examining the interaction of the eosinophil with the cellular arm of the immune system (Basten and Beeson, 1970; Ruscetti et al., 1976; Beeson and Bass, 1977; Raghavachar et al., 1987; Ohnishi et al., 1988). The purpose of this review is to provide a brief overview of the structure and biology of the mammalian eosinophil and to emphasize the fact that eosinophils fulfil a paradoxical role as effectors of tissue damage and as benign modulators of inflammation.

[Allergic rhinitis nasal epithelial cell conditioned medium stimulates growth and differentiation of basophil/mast cell and eosinophil progenitors from atopic blood]

We examined the conditions, kinetics and cell sources for basophil/mast cell and eosinophil colony stimulating activity (CSA) production by nasal epithelial cells taken from house dust (HD) nasal allergic patients. Epithelial scrapings removed from HD nasal allergic patients were grown to confluence over 7 days as a monolayer of epithelial cells in medium supplemented with fetal calf serum (FCS) on collagen coated microwell plates. CSA in nasal epithelial cells conditioned medium (CM) was assessed with density-gradient separated, nonadherent peripheral blood mononuclear cells in 14-day and 21-day methylcellulose assays. In the 14-day methylcellulose assays, the number of Eo-type colonies in the presence of either 10% or 5% CM was significantly higher than the background number of Eo-type colonies (negative control). Comparison of Gm CSA among 1%, 5% and 10% CM with negative, revealed no significant differences. We also compared the Eo-type CSA in the presence of 10% significant differences. We also compared the Eo-type CSA in the presence of 10% CM in the 14-day methylcellulose assay with 21-day methylcellulose assay. There was no significant difference in the number of Eo-type colony between the 14-day and 21-day methylcellulose assays. We also examined the composition of the cells in the colonies in the 14-day and 21-day methylcellulose cultures. The percentage of metachromatic granule containing cells in a Eo-type colony in 14-day methylcellulose assay was significantly higher than in a Eo-type colony in 21-day methylcellulose assay.(ABSTRACT TRUNCATED AT 250 WORDS)

Monocyte-macrophage differentiation induced by human upper airway epithelial cells

We examined the ability of conditioned medium (CM) generated by human upper airway epithelial (Ep) cells from normal (NN) and inflamed, allergic rhinitis (AR) and nasal polyp (NP) tissues to induce monocytic differentiation of hemopoietic progenitors of the HL-60 myeloid leukemia cell line in vitro. In HL-60 cells cultured in RPMI with 10% FBS, there was differentiation to 0.4 +/- 0.4% monocytic cells. NN-, AR-, and NP-EpCM induced differentiation to 23 +/- 6%, 42 +/- 11%, and 71 +/- 10% monocytic cells, respectively. EpCM also induced isolated peripheral blood nonadherent mononuclear cells to express monocyte/macrophage-specific antigens as detected by immunohistochemistry using FMC-32 monoclonal antibodies (anti-CD14). We also examined the cytokine content of these EpCMs and found that they contained granulocyte/macrophage colony-stimulating factor (GM-CSF): 126 +/- 35, 198 +/- 22, and 489 +/- 118 pg/ml for NN-, AR-, and NP-EpCM, respectively. These CMs also contained granulocyte-CSF (G-CSF) and interleukin-6 (IL-6), but there were no significant differences between normal and inflamed tissue-derived cell supernatants. No macrophage-CSF (M-CSF) was detected in these EpCMs. Recombinant human GM-CSF, G-CSF, and IL-6, alone and in combinations, at doses similar to or greater than those found in the EpCMs, did not induce comparable monocytic differentiation of HL-60 cells. Preincubation of the EpCM with neutralizing anti-GM-CSF, anti-G-CSF, or anti-IL-6 antibodies did not significantly inhibit the monocytic differentiation induced by the EpCM.(ABSTRACT TRUNCATED AT 250 WORDS)

The growth and differentiation of mast cells

Mast cells (MCs) are local immune cells involved in host defense mechanisms and allergic response. They usually develop from MC committed progenitor cells which in turn are derived from uncommitted hemopoietic stem cells. MC precursors are supposed to develop in the bone marrow (bm) cavities as well as in extramedullary tissues. MC precursor cells also have the potential to circulate in the blood stream. After homing in the tissues they give rise to mature MCs. Recruitment and differentiation as well as terminal maturation of MCs is regulated by a complex network of factors. Two major arms of control have been delineated based on in vitro studies and experimental animal models. The first involves the response of the progenitor cells to growth inducing cytokines, such as IL-3. This type of control promotes the generation of MC precursor cells. The second arm of control involves the microenvironmental network interacting with the MC progenitors. It consists of both stroma cell- and immune cell-derived differentiation factors and the direct interaction of cells. It may be important for homing of MC progenitors during embryogenesis and probably throughout life. The stromal component also determines terminal differentiation towards a particular type of MCs and also supports in vitro development of MCs in long term cultures. Growth and function of the mature MCs in the various tissues may be triggered by additional factors including the interactions of MCs with other leukocytes and nerve cells. The coupling of MC activation processes with subsequent proliferation may be a triggering factor in allergic disease. This article attempts to provide a synthesis of current knowledge on MC development.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in nasal metachromatic cells during allergen immunotherapy

We have investigated changes of nasal metachromatic cell number, nasal symptoms and nasal provocation at the third and sixth month during allergen immunotherapy. Twenty-five subjects with perennial allergic rhinitis (house dust (23), Alternaria (2) were divided into two groups: an immunotherapy-treated group (n = 14) and a control group (n = 11). At the first visit nasal symptom scores, nasal provocation reactions and the number of metachromatic cells in nasal mucosal epithelial scrapings were not significantly different between groups. At the third and sixth month after immunotherapy nasal symptom scores, nasal provocation and the metachromatic cells in epithelial scrapings were significantly reduced (P less than 0.05) compared with the pretreatment values in the immunotherapy group, but unchanged in the control group. These results suggest that the reduction in metachromatic cell number at the nasal mucosal surface may be one of the mechanisms which could explain the improvement of nasal allergic symptoms by immunotherapy.

The increased number of epithelial mast cells in nasal polyps and adjacent turbinates is not allergy-dependent

Respiratory epithelial mast cells are an expression of airway inflammatory processes. Nasal epithelial mast cells are known to be increased in allergic rhinitis and have now been examined in patients with nasal polyps. Metachromatic cell counts (mean +/- standard error) expressed as the sum of large mast cells, atypical mast cells and basophils in epithelial scrapings of the inferior turbinates, assessed after Carnoy's fixation and toluidine blue staining (pH 0.5), were 37.5 +/- 29 in non-allergic normal control subjects (n = 11), 435 +/- 130 in polyp patients who were allergic (n = 18), and 699 +/- 267 in polyp patients who were not allergic (n = 8). Metachromatic cell counts in epithelial scrapings obtained in vivo from nasal polyps of allergic patients (n = 8) were 1769 +/- 962, and 2308 +/- 1544 from polyps of non-allergic patients (n = 5); metachromatic counts were 2089 +/- 633 in epithelial scrapings from excised polyps of allergic patients (n = 14) and 2214 +/- 640 from polyps of non-allergic patients (n = 13). It is concluded that the number of metachromatic cells in the epithelium of nasal polyps and the adjacent nasal mucosa is elevated compared with normal nasal epithelium and the increased number does not depend upon allergy.

Hematopoietic growth factor production by cultured cells of human nasal polyp epithelial scrapings: kinetics, cell source, and relationship to clinical status

The conditions and cell sources for colony stimulating activity (CSA) production by nasal polyp epithelial scrapings were examined. Epithelial scrapings removed from patients were grown to confluence during 7 days as monolayers of epithelial cells in media supplemented with fetal calf serum (FCS) on collagen-coated microwell plates. Growth kinetics of nasal polyp epithelial cells (NPECs) were determined, and CSA in NPEC conditioned medium (CM) was assessed with density-gradient separated, nonadherent peripheral blood mononuclear cells in standard 14-day methylcellulose assays. Nasal polyp cultures in the presence of 5% or 15% FCS (vol/vol) demonstrated significantly more epithelial cell proliferation than cultures at 0% and 1% FCS. There were comparable metachromatic cell counts in polyp epithelial scrappings from allergic and nonallergic donors. Similarly, NPEC CM from allergic and nonallergic donors had equivalent CSA for basophil/mast cell (BMC) and eosinophil (EO) lineages, respectively. CSA production was enhanced under conditions of higher FCS concentration and NPEC proliferation. These studies confirm an epithelial cell origin of BMC and EO growth and differentiation factors derived from nasal polyps and point to the existence of a unique microenvironment for BMC and EO development provided by polyp epithelium that appears to be independent of the presence of an allergic diathesis.