Granulocyte/macrophage-colony stimulating factor in allergen-induced rhinitis: cellular localization, relation to tissue eosinophilia and influence of topical corticosteroid

BACKGROUND

Allergen-induced late nasal responses are associated with recruitment of T lymphocytes and eosinophils, and preferential messenger RNA (mRNA) expression of 'TH2-type' cytokines. We previously showed that topical steroid inhibited the late response and associated tissue eosinophilia. In this study we tested the hypothesis that granulocyte/macrophage-colony stimulating factor (GM-CSF) may contribute to late-responses and tissue eosinophilia and is inhibitable by topical corticosteroid.

METHODS

Nasal biopsies were taken before and 24 h after nasal allergen provocation following 6 weeks of treatment with either a nasal corticosteroid spray (fluticasone propionate) or a matched placebo nasal spray twice daily. Cryostat sections were processed by immunohistochemistry and in situ hybridization to assess cytokine mRNA expression for GM-CSF.

RESULTS

Increases in T lymphocytes and eosinophils were seen in the nasal mucosa after allergen challenge (p = 0.01) which were accompanied by a 5-fold increase in cells expressing mRNA for GM-CSF (p = 0.01). Double immunohistochemistry/in situ hybridization demonstrated that the majority of GM-CSF mRNA+ cells were co-localized to CD68+ (40%), or T cells (40%) with a lesser contribution from eosinophils (<20%). Topical steroid treatment was accompanied by a decrease in both the CD3+ and major basic protein (MBP+) cells expressing GM-CSF mRNA (p = 0.01) with a corresponding proportionate increase in the % of macrophages expressing GM-CSF.

CONCLUSIONS

The results indicate that after allergen provocation, eosinophils are recruited to the nasal mucosa and that, at least in part, this may be due to GM-CSF. Topical nasal corticosteroid inhibits late responses and the associated eosinophilia, possibly indirectly by decreasing GM-CSF from T lymphocytes or reducing autocrine production of GM-CSF from eosinophils.

Nasal eosinophilia and IL-5 mRNA expression in seasonal allergic rhinitis induced by natural allergen exposure: effect of topical corticosteroids

BACKGROUND

Nasal allergen provocation in patients with allergic rhinitis leads to expression of the proeosinophilic cytokines IL-5 and GM-CSF and tissue eosinophilia.

OBJECTIVE

We sought to examine the effect of natural seasonal allergen exposure on IL-5 and GM-CSF mRNA expression and nasal eosinophilia and to evaluate the effects of topical corticosteroid therapy on these responses.

METHODS

Nasal biopsy specimens were collected from 46 grass pollen-sensitive patients with seasonal rhinitis before the grass pollen season. A second biopsy specimen was collected during the pollen season, by which time patients had received 6 weeks treatment with either fluticasone propionate (200 micro(g) twice daily) or placebo nasal spray.

RESULTS

Fluticasone treatment was clinically effective (P <.005). Patients receiving placebo, but not fluticasone, showed increased numbers of epithelial and submucosal EG2+ eosinophils (P <.005) and IL-5 and GM-CSF mRNA-expressing cells (P <.0001) during the pollen season. Colocalization experiments showed that greater than 80% of IL-5 mRNA-expressing cells were submucosal CD3+ T cells in both groups. The numbers of submucosal CD3+ T cells did not increase during the pollen season or decrease with fluticasone treatment. Fluticasone also inhibited IL-5 secretion by grass pollen-stimulated peripheral blood T cells from patients with seasonal rhinitis (n = 5, inhibitory concentration of 50% = 10(-9) to 10(-10) mol/L).

CONCLUSIONS

These results suggest that topical corticosteroids may reduce eosinophilia in seasonal rhinitis by inhibiting T cell IL-5 production.

Expression of IL-4, Cepsilon RNA, and Iepsilon RNA in the nasal mucosa of patients with seasonal rhinitis: effect of topical corticosteroids

BACKGROUND

Nasal allergen provocation has demonstrated that allergen-induced rhinitis is associated with an increase in local IL-4 mRNA and IgE heavy chain (Cepsilon) and IgE heavy chain promoter (Iepsilon) RNA and that pretreatment with topical glucocorticosteroids inhibits the increase in these transcripts.

OBJECTIVE

This study was undertaken to determine whether observations made after acute allergen provocation can be extended to the case of chronic exposure experienced during the pollen season.

METHODS

Biopsy specimens were obtained from the inferior turbinate of 33 pollen-sensitive subjects with allergic rhinitis before and during pollen season. Patients were randomized in a double-blind fashion and treated with either topical steroids (200 microg fluticasone propionate twice daily; n = 16) or matched placebo nasal spray (n = 17) before the pollen season. Alkaline phosphatase anti-alkaline phosphatase immunocytochemistry was used to identify B cells (CD20+), and in situ hybridization was used to detect IL-4, Cepsilon, and Iepsilon RNA+ cells.

RESULTS

Baseline examination revealed IL-4 and Cepsilon RNA but virtually no Iepsilon RNA+ cells in the nasal mucosa. Analysis revealed a significant difference in the expression of Cepsilon and Iepsilon RNA+ cells (p < 0.001). Biopsy specimens taken after antigen exposure exhibited highly significant increases in placebo-treated (p < 0.001) but not steroid-treated patients. In both groups, the number of CD20+ cells was unchanged when preexposure and postexposure biopsy specimens were compared.

CONCLUSIONS

These results show strong support for the hypothesis that IgE class switching occurs locally within the nasal mucosa of subjects with seasonal allergic rhinitis and that this response can be inhibited through strategies directed against local IgE production.

Expression of epsilon germ-line gene transcripts and mRNA for the epsilon heavy chain of IgE in nasal B cells and the effects of topical corticosteroid

We have studied the expression of the gene encoding the epsilon heavy chain of IgE in nasal B cells of hayfever patients. We developed probes to detect transcripts of the epsilon germ-line gene and the rearranged gene by in situ hybridization of biopsy sections from the nasal mucosa. We compared tissue from hayfever patients out of season with that of normal controls, and also of hayfever patients treated with topical corticosteroid (fluticasone propionate) or placebo for 6 weeks and then challenged with antigen. epsilon chain mRNA was expressed in an unexpectedly high proportion of nasal B cells of both hayfever patients and normal subjects. However, although similar numbers of B cells were found in both groups, the proportion of cells that express epsilon chain mRNA was several times higher in the hayfever patients. No transcripts of the epsilon germ-line gene were detected in either group before allergen challenge. When hayfever patients were administered antigen locally, early (10-30 min) and late (1-24 h) symptoms ensued. After 24 h, coincident with an increase in the number of cells expressing mRNA for IL-4 in the tissue, epsilon germ-line gene transcripts appeared in the nasal B cells. The induction by allergen of IL-4 mRNA and epsilon germ-line gene transcripts was suppressed by fluticasone propionate treatment. Our results suggest that local IgE synthesis and cytokine regulation of heavy chain switching to IgE occur in the nasal mucosa.

IL-13 mRNA and immunoreactivity in allergen-induced rhinitis: comparison with IL-4 expression and modulation by topical glucocorticoid therapy

The allergen-induced late nasal response (LNR) is associated with high expression of interleukin-4 (IL-4) and IL-5 messenger RNA (mRNA) in the nasal mucosa, suggesting a role for Th2-type cytokines in the development of the LNR. Moreover, topical corticosteroid-mediated inhibition of the LNR is accompanied by inhibition of IL-4, but not IL-5, mRNA expression, IL-13 shares a number of functions with IL-4, including IgE switching and vascular cell adhesion molecule-1 (VCAM-1) upregulation. We investigated the expression of IL-13 mRNA and immunoreactivity in nasal biopsies from 10 normal subjects and 20 subjects with allergic rhinitis. IL-4 mRNA expression was examined in the same subjects. The allergic rhinitis patients were randomized to receive a 6-wk treatment with either topical fluticasone propionate (n = 10) or placebo (n = 10) nasal spray twice daily. A nasal biopsy was taken before treatment and 24 h after local nasal allergen provocation with a grass-pollen extract. Before treatment, there was no significant difference between the allergic rhinitis patients and controls in the expression of IL-13 mRNA and immunoreactivity. After allergen provocation, we observed a significant increase in IL-13 mRNA-positive and immunoreactive cells at 24 h only in subjects given placebo (P < 0.001). Inhibition of the LNR after corticosteroid treatment was associated with a marked decrease in allergen-induced IL-13 mRNA-positive (P < 0.001) and immunoreactive cells (P < 0.001). In subjects given placebo, 76.9 +/- 5.5% of IL-13 mRNA-positive cells observed after allergen were CD3+, whereas 11.2 +/- 2.7% coexpressed immunoreactivity for mast-cell tryptase. In these subjects, increases in cells expressing IL-13 mRNA were greater than for IL-4 mRNA (P = 0.001), and double in situ hybridization studies revealed that 100% of the IL-4 mRNA-positive cells coexpressed IL-13 mRNA, whereas 66.6 +/- 10.5% of IL-13 mRNA-positive cells coexpressed IL-4 transcripts after allergen challenge. The results of this study suggest that IL-13 expression is a prominent feature of the LNR, and that inhibition of the LNR following steroid therapy may be partly attributable to inhibition of IL-13 expression.

T lymphocytes and mast cells express messenger RNA for interleukin-4 in the nasal mucosa in allergen-induced rhinitis

We have investigated the phenotype of interleukin-4 (IL-4) mRNA+ cells in the nasal mucosa of six subjects with allergic rhinitis before and 24 hr after local allergen provocation with grass pollen extract. Serial cryostat sections were cut from paraformaldehyde-fixed snap-frozen nasal biopsies, and immunocytochemistry (APAAP) followed by in situ hybridization performed on the same sections. For immunocytochemistry, antibodies against CD3, tryptase, major basic protein (MBP) and CD68 were used to identify T cells, mast cells, eosinophils and macrophages, respectively. Hybridization studies were performed using a digoxigenin-labelled IL-4 riboprobe. Nitroblue tetrazolium (NBT) and X-phosphate-5-bromo-4-chloro-3-indoly phosphate (BCIP) served as chromogens to detect hybridization IL-4 mRNA signals. Significant increases in T lymphocytes and eosinophils and in the number of IL-4 mRNA+ cells were observed after allergen challenge. Double immunocytochemistry/in situ hybridization demonstrated that the majority of IL-4 mRNA+ cells after allergen challenge were CD3+ (73.7% +/- 1.6). Lower numbers of IL-4 mRNA hybridization signals were co-localized to tryptase+ cells (26.0% +/- 1.6). In contrast, no IL-4 mRNA hybridization signals were co-localized to either eosinophils or macrophages. These results indicate that after allergen challenge T cells are the principal cellular source of IL-4 mRNA transcripts during human late nasal responses, with a lesser contribution from mast cells.

Topical glucocorticosteroid (fluticasone propionate) inhibits cells expressing cytokine mRNA for interleukin-4 in the nasal mucosa in allergen-induced rhinitis

Allergen-induced late nasal responses are associated with recruitment and activation of T lymphocytes and eosinophils and preferential mRNA expression for T-helper type 2 (Th2) cytokines. We tested the hypothesis that topical corticosteroids may inhibit late responses by inhibiting cells expressing mRNA for Th2 cytokines. A randomized double-blind placebo-controlled trial of topical corticosteroid (fluticasone propionate) was performed in 48 adult grass pollen-sensitive patients. Nasal biopsies were taken at baseline and repeated 24 hr after local nasal allergen provocation following 6 weeks treatment with either fluticasone propionate 200 micrograms or placebo nasal spray twice daily. Baseline mRNA expression for interleukin-4 (IL-4) (P = 0.01) and IL-5 (P = 0.002) was higher in the patients than in normal controls. Topical corticosteroid treatment significantly inhibited immediate nasal symptoms, with almost complete inhibition of the late response following allergen challenge. This was associated with a marked decrease in the allergen-induced increases in cells expressing mRNA for IL-4 (P = 0.002) but not for IL-5. Inhibition of the late response was also accompanied by decreases in CD25+ cells, presumed T lymphocytes and eosinophils. A significant correlation was observed between the decreases in IL-4 mRNA+ cells and in eosinophils after treatment (r = 0.46, P < 0.05). These results suggest that prolonged treatment with topical corticosteroid inhibits allergen-induced early and late nasal responses and the associated tissue eosinophilia, and that, at least in part, this may result from inhibition of cells expressing mRNA for IL-4.