The novel use of the human nasal epithelial cell line RPMI 2650 as an in vitro model to study the influence of allergens and cytokines on transforming growth factor-β gene expression and protein release

BACKGROUND: The epithelial accumulation of mast cells is a feature of allergic rhinitis and this has been linked to the expression of the known mast cell chemoattractant transforming growth factor-beta (TGF-beta) at this site. Little is known concerning the regulation of TGF-beta gene expression or protein release by nasal epithelial cells. To address this we have utilized the RPMI 2650 human nasal epithelial cell line, which has some features that closely resemble normal nasal epithelium and has been reported to secrete a TGF-beta-like molecule. OBJECTIVES: To investigate the regulation of TGF-beta gene expression and protein secretion in RPMI 2650 nasal epithelial cells following exposure to allergens (house dust mite (HDM) and grass pollen) and mast cell associated T-helper type 2 (Th2) cytokines (IL-4, IL-13, and TNF-alpha). Methods Light and scanning electron microscopy was used to evaluate the morphology of RPMI 2650 cells in culture, enzyme-linked immunosorbent assay was used to investigate their TGF-beta secretory capacity and the identification of the TGF-beta isotype(s) involved, flow cytometry was used to demonstrate the presence of TGF-beta receptors on the RPMI 2650 cells, and the quantitative real-time TaqMan PCR was used to measure TGF-beta gene expression. RESULTS: TGF-beta(2) was identified as the main isotype secreted by the RPMI 2650 cells. HDM allergens and TNF-alpha increased both TGF-beta gene expression and protein release from these cells, whereas grass pollen, IL-4, and IL-13 were without effect. CONCLUSIONS: The RPMI 2650 nasal epithelial cell line represents a valid in vitro model to evaluate the regulation of TGF-beta biology. In this system HDM allergens have stimulatory activity that is fundamentally different from that of grass pollen allergens, and the Th2 cytokines IL-4 and IL-13 are without effect. The ability of TNF-alpha to up-regulate both TGF-beta gene expression and protein release indicates that mast cell-epithelial interactions concerning TGF-beta are bi-directional and this may be fundamental to epithelial immunoregulation. The availability of a model system, such as the RPMI 2650 cells, will enable the early evaluation of future novel and targeted interventions directed toward the aberrant responses of upper airway structural cells.     

Regulated production of the T helper 2-type T-cell chemoattractant TARC by human bronchial epithelial cells in vitro and in human lung xenografts

The chemokine TARC is a ligand for the chemokine receptor CCR4 expressed on T helper (Th)2-type CD4 T cells. Allergic airway inflammation is characterized by a local increase in cells secreting Th2-type cytokines. We hypothesized that bronchial epithelial cells may be a source of chemokines known to chemoattract Th2 cells. Regulated TARC expression was studied using normal human bronchial epithelial cells and a human lung xenograft model. TARC expression was increased in normal human bronchial epithelial cells in response to tumor necrosis factor-alpha stimulation, and further upregulation of TARC was observed with interferon (IFN)-gamma but not interleukin (IL)-4 costimulation. TARC functions as a nuclear factor (NF)-kappa B target gene, as shown by the abrogation of TARC expression in response to proinflammatory stimuli when NF-kappa B activation is inhibited. In an in vivo model, minimal constitutive TARC expression was observed in human lung xenografts. Consistent with our findings in vitro, TARC messenger RNA (mRNA) expression was upregulated in the xenografts in response to IL-1, and costimulation with IFN-gamma but not IL-4 further increased TARC mRNA and protein expression. In addition, bronchoalveolar lavage fluid from asthmatic subjects after allergen challenge contained significantly increased levels of TARC, suggesting that TARC production by bronchial epithelial cells may play a role in the pathogenesis of allergic asthma.     

Increased expression and role of thymic stromal lymphopoietin in nasal polyposis

Purpose

Nasal polyposis is a chronic inflammatory disease of the upper airways often associated with asthma and characterized by markedly increased numbers of eosinophils, Th2 type lymphocytes, fibroblasts, goblet cells and mast cells. Previous studies have shown elevated levels of thymic stromal lymphopoietin (TSLP) in atopic diseases like asthma, atopic dermatitis and mainly in animal models of allergic rhinitis (AR). Here, we investigated the expression of TSLP in nasal polyps from atopics and non-atopics in comparison with the nasal mucosa and its potential role in nasal polyposis.

Methods

Messenger RNA expression for TSLP, thymus and activation-regulated chemokine (TARC) and macrophage derived chemokine (MDC) in nasal polyps and nasal mucosa of atopics and non-atopics was analyzed by real time PCR. Immunoreactivity for TSLP in nasal polyps and in the nasal mucosa of patients with AR and non-allergic rhinitis (NAR) was analyzed by immunohistochemistry. Eosinophil counts was analyzed by Wright-Giemsa staining and nasal polyp tissue IgE, by ELISA.

Results

Messenger RNA expression for TSLP,TARC and MDC was markedly higher in nasal polyps as compared to the allergic nasal mucosa. Immunoreactivity for TSLP was detected in epithelial cells, endothelial cells, fibroblasts and inflammatory cells of the nasal mucosa and nasal polyps. The number of TSLP+ cells was significantly greater in the nasal mucosa of AR than NAR patients. The number of TSLP+ cells in nasal polyps from atopics was significantly greater than that of non-atopics and that in the allergic nasal mucosa. The number of TSLP+ cells correlated well with the number of eosinophils and the levels of IgE in nasal polyps.

Conclusions

The high expression of TSLP in nasal polyps and its strong correlation to eosinophils and IgE suggest a potential role for TSLP in the pathogenesis of nasal polyps by regulating the Th2 type and eosinophilic inflammation.     

Th2- and to a lesser extent Th1-type cytokines upregulate the production of both CXC (IL-8 and gro-alpha) and CC (RANTES,eotaxin, eotaxin-2, MCP-3 and MCP-4) chemokines in human airway epithelial cells

BACKGROUND: Both CXC and CC chemokines play an important role in leukocyte recruitment. However, a systematic examination of their production by human airway epithelial cells (HAECs) has not been carried out. The objective of this study was to investigate whether Th1- and Th2-type cytokines regulate chemokine production in HAECs. METHODS: HAECs were grown from both nasal and bronchial tissue and subsequently stimulated with either Th1- or Th2-type cytokines. RESULTS: Constitutive mRNA expression for gro-alpha, IL-8 and RANTES was seen in both human nasal and human bronchial epithelial cells. IL-4 was the strongest stimulus for both gene expression and protein production of the chemokines RANTES, IL-8 and gro-alpha, while both IL-13 and IFN-gamma were weaker inducers of these chemokines, with the exception of gro-alpha (IL-13 was a strong stimulus for gro-alpha production). TNF-alpha synergized with IL-4, and to a lesser extent with IFN-gamma and IL-13, to release RANTES, IL-8 and gro-alpha. IL-4 and to a lesser extent IL-13 and IFN-gamma stimulated the production of MCP-3 and -4, eotaxin and eotaxin-2 immunoreactivities. However, no induction of the mRNAs encoding these chemokines was observed, suggesting that they may be released from a preformed pool within the HAECs. CONCLUSION: These findings suggest that when released into the airways, Th2- and to a lesser extent Th1-type cytokines may stimulate recruitment of eosinophils and neutrophils through the release of CC (RANTES, MCP-3 and -4, eotaxin and eotaxin-2) and CXC chemokines (gro-alpha and IL-8).     

Interleukin-4-independent production of Th2 cytokines by nasal lymphocytes and nasal eosinophilia in murine allergic rhinitis

BACKGROUND: Interleukin (IL)-4 is believed to play an important role in the atopic pathogenesis. However, the precise role of IL-4 in the in vivo initiation of allergic rhinitis is not fully understood. We have recently found that BALB/c mice sensitized intranasally with Schistosoma mansoni egg antigen (SEA) mount a Th2 response that initiates allergic rhinitis. Thus, we sought to determine the role of IL-4 in the initiation of allergic rhinitis in vivo with this model. METHODS: IL-4 gene-deficient (IL-4 -/-) BALB/c and wild-type (IL-4 +/+) control mice were sensitized by intranasal SEA administration, and their immunologic responses were examined both in vivo and in vitro. RESULTS: IL-4 +/+ mice sensitized with SEA displayed significantly higher titers of SEA-specific IgG1 and IgE antibodies than IL-4-/- mice, while the latter produced significantly more SEA-specific IgG2a. Antigen-stimulated nasal lymphocytes from SEA-sensitized IL-4 -/- and IL-4 +/+ mice produced similar amounts of IL-5 and IL-10, but neither produced IFN-gamma. Furthermore, the severity of nasal eosinophilia was similar in both groups. CONCLUSIONS: These results indicate that although IL-4 is necessary for the production of Th2-associated antibodies--in particular, IgE--it is not required for either the production of the Th2-associated cytokines IL-5 and IL-10, or the induction of nasal eosinophilia.     

Cellular infiltration and cytokine mRNA expression in perennial allergic rhinitis

BACKGROUND: Allergen challenge in allergic rhinitis patients leads to local eosinophilia and Th2-type cytokine expression. Natural exposure to grass pollen is additionally characterized by epithelial mast-cell infiltration. We hypothesized that perennial allergic rhinitis is also associated with T-cell and eosinophil infiltration of the nasal mucosa, local Th2-type cytokine expression, and increased numbers of nasal epithelial mast cells. METHODS: Nasal biopsies from perennial allergic rhinitis patients and controls were analysed by immunocytochemistry for different cell populations and in situ hybridization for cytokine mRNA-expressing cells. RESULTS: Perennial allergic rhinitis was associated with increased numbers of submucosal CD3+ T cells (P=0.05), EG2+ activated eosinophils (P=0.01), and CD68+ macrophages (P=0.01) compared to controls. Epithelial, but not submucosal, tryptase-positive mast cells were also elevated in rhinitics compared to controls (P=0.01). The numbers of cells expressing interleukin (IL)-5 were higher (P=0.01) and the numbers of cells expressing IL-2 were lower (P=0.04) in rhinitic patients than controls. There were no significant differences for either IL-4 or interferon-gamma between the groups. CONCLUSIONS: Perennial allergic rhinitis is characterized by mast-cell migration into the epithelium; submucosal infiltration by T cells, eosinophils, and macrophages; and an imbalance in local T-cell cytokine production in favour of enhanced IL-5 and reduced IL-2 expression.     

Human epithelial cells trigger dendritic cell mediated allergic inflammation by producing TSLP

Whether epithelial cells play a role in triggering the immune cascade leading to T helper 2 (T(H)2)-type allergic inflammation is not known. We show here that human thymic stromal lymphopoietin (TSLP) potently activated CD11c(+) dendritic cells (DCs) and induced production of the T(H)2-attracting chemokines TARC (thymus and activation-regulated chemokine; also known as CCL17) and MDC (macrophage-derived chemokine; CCL22). TSLP-activated DCs primed na?ve T(H) cells to produce the proallergic cytokines interleukin 4 (IL-4), IL-5, IL-13 and tumor necrosis factor-alpha, while down-regulating IL-10 and interferon-gamma. TSLP was highly expressed by epithelial cells, especially keratinocytes from patients with atopic dermatitis. TSLP expression was associated with Langerhans cell migration and activation in situ. These findings shed new light on the function of human TSLP and the role played by epithelial cells and DCs in initiating allergic inflammation.     

TNF-alpha contributes to the development of allergic rhinitis in mice

BACKGROUND: Allergic rhinitis is an inflammation involving T(H)2-type cytokine production, with pathologic eosinophil infiltration in the nasal mucosa. Although TNF-alpha is thought to be a pro-inflammatory cytokine, the relationship between TNF-alpha and allergic rhinitis has not been clarified. OBJECTIVES: The role of TNF-alpha in a murine model of ovalbumin (OVA)-sensitized allergic rhinitis was investigated by using mice deficient in the gene encoding TNF-alpha (TNF-alpha(-/-) mice). METHODS: Both wild-type (TNF-alpha(+/+)) and TNF-alpha(-/-) mice were sensitized with OVA by means of intraperitoneal injection. They were then challenged with intranasal OVA, and various allergic responses were assessed. RESULTS: The production of OVA-specific IgE in the serum (P <.05) and the frequency of sneezes (P <.05) and nasal rubs (P <.05) decreased significantly in TNF-alpha(-/-) mice after OVA sensitization compared with that in TNF-alpha(+/+) mice (P <.05). The mRNA expression of IL-4, IL-10, and eotaxin in nasal mucosa in TNF-alpha(-/-) mice was also significantly suppressed compared with that in TNF-alpha(+/+) mice after OVA sensitization (P <.05). Furthermore, the expression of both endothelial-leukocyte adhesion molecule 1 and vascular cell adhesion molecule 1 mRNA in the nasal mucosa was significantly suppressed (P <.05), although intercellular adhesion molecule 1 mRNA expression did not decrease significantly in TNF-alpha(-/-) mice compared with that in TNF-alpha(+/+) mice after OVA sensitization. In addition, the effect of TNF-alpha on endothelial-leukocyte adhesion molecule 1 and vascular cell adhesion molecule 1 expression by means of Western blot analysis was compatible with the mRNA results. Pathologically, eosinophil infiltration in nasal mucosa was significantly restricted in TNF-alpha(-/-) mice compared with in TNF-alpha(+/+) mice after OVA sensitization (P <.05). CONCLUSION: TNF-alpha is necessary for antigen-specific IgE production and for the induction of T(H)2-type cytokines and chemokines. Furthermore, TNF-alpha might be important for the expression of adhesion molecules to recruit eosinophils to the allergic inflammatory site. We conclude that the lack of TNF-alpha inhibited the development of allergic rhinitis.     

IL-4, IL-10 and IL-13 down-regulate monocyte-chemoattracting protein-1 (MCP-1) production in activated intestinal epithelial cells

Several studies have demonstrated that intestinal epithelial cells play a major role in the initiation and perpetuation of intestinal inflammation by secreting proinflammatory cytokines and chemokines. MCP-1 is suggested to be a chemokine that plays a major part during intestinal inflammation in inflammatory bowel disease (IBD). Immunoregulatory cytokines such as IL-4, IL-10 and IL-13 have been described to exert anti-inflammatory properties on various cell types. The aim of our study was to determine the effect of Th2 cytokines on the production of MCP-1 by activated intestinal epithelial cells. We examined Caco-2 cells as well as intestinal epithelial cells which were isolated from surgical specimens. Production of the chemokine MCP-1 was determined under stimulated and non-stimulated conditions. IL-4, IL-10 and IL-13 were added to stimulated epithelial cells under various culture conditions. Supernatants were analysed for cytokine concentrations using ELISAs. Under stimulation with physiological agents like IL-1β or tumour necrosis factor-alpha (TNF-α), we observed markedly increased concentrations of MCP-1 in supernatants of Caco-2 cells and intestinal epithelial cells. IL-4, IL-10 and IL-13 all had the capacity to down-regulate the production of MCP-1 in Caco-2 cells as well as in freshly isolated epithelial cells. Caco-2 cells which were primed with Th2 cytokines 24 h before stimulation were subsequently decreased in their ability to be stimulated by IL-1β or TNF-α for MCP-1 production. As MCP-1 has been shown to play a major role during intestinal inflammation, the in vitro suppression of MCP-1 in enterocytes suggests the in vivo use of regulatory cytokines in patients with active IBD.     

Increased expression of HLA-DR and CD86 in nasal epithelial cells in allergic rhinitics: antigen presentation to T cells and up-regulation by diesel exhaust particles

BACKGROUND: A proportion of nasal epithelial cells (NEC) in patients with allergic rhinitis (AR) are known to express the major histocompatibility complex Class II molecule (HLA-DR). OBJECTIVE: We hypothesized that NEC may play a role in antigen presentation to T cells. To elucidate the possible role of NEC in antigen presentation, we examined the expression of HLA-DR, CD80 and CD86 in NEC, their regulation by cytokines and the capacity of NEC to induce antigen-specific proliferation of T cells. METHODS: We examined the expression of HLA-DR, CD80 and CD86 in nasal epithelial scrapings of patients with seasonal allergic rhinitis (SAR) to Japanese cedar pollen pre-season and in-season, by immunohistochemistry. Next, we examined the effect of IL-1beta, TNF-alpha, (IFN-gamma), IL-4 alpha, IL-13 and diesel exhaust particles (DEP) on the HLA-DR, CD80 and CD86 expression in cultured nasal epithelial cells (CNEC), by flow cytometry. Further, we analysed the capacity of mite antigen (Der f II)-pulsed mitomycin-C-treated CNEC to induce proliferation of autologous T cells from patients with perennial allergic rhinitis. RESULTS: NEC constitutively expressed HLA-DR and CD86, but not CD80. The expression of HLA-DR and CD86 in NEC was significantly increased in-season, in patients with SAR as compared with that of pre-season. While IFN-gamma up-regulated the expression of HLA-DR, IL-1beta and TNF-alpha up-regulated the expression of CD86 in CNEC. Furthermore, in the presence of mite antigen, CNEC induced the proliferation of autologous peripheral blood T lymphocytes. Anti-CD86 and anti-HLA-DR monoclonal antibody but not anti-CD80 inhibited the epithelial cell-induced T cell proliferation. Stimulation with a combination of DEP and mite antigen significantly up-regulated HLA-DR and CD86 expression in CNEC. CONCLUSIONS: These studies suggest that NEC in patients with AR may play a role in antigen presentation through the enhanced expression of HLA-DR and CD86. Furthermore, these results suggest the possibility that DEP may enhance the antigen-presenting function of CNEC.     

Suplatast tosilate inhibits thymus- and activation-regulated chemokine production by antigen-specific human Th2 cells

BACKGROUND: Suplatast tosilate is an anti-allergic agent that suppresses cytokine production by human Th2 cells. OBJECTIVE: We investigated the effects of suplatast tosilate on the production of thymus- and activation-regulated chemokine (TARC) by T cells from allergic patients with asthma. METHODS: Purified protein derivative (PPD)-specific Th1 cell lines and Dermatophagoides farinae (Der f)-specific Th2 cell lines were established from nine patients with house dust mite-allergic asthma. The effects of suplatast tosilate on mRNA expression of TARC and protein production of TARC from antigen-specific Th1 or Th2 cell lines were investigated after stimulation with relevant antigens or phytohemagglutinin (PHA). In addition, the effects of IL-4, IL-10, and IFN-gamma on TARC production by Der f-specific Th2 cell lines in the presence or absence of suplatast tosilate were studied. RESULTS: Although PPD-specific Th1 cell lines did not produce TARC after stimulation with PPD antigen or PHA, stimulation of Der f-specific Th2 cell lines with Der f antigen or PHA increased production of TARC. Suplatast tosilate significantly and dose-dependently inhibited production of TARC by Der f-specific Th2 cell lines stimulated with either Der f antigen (76.5% inhibition at 100 microg/mL, P < 0.01) or PHA (81.9% inhibition at 100 microg/mL, P < 0.01). TARC production by Der f-specific Th2 cell lines was significantly increased only by activation with IL-4 but not with IL-10 or IFN-gamma; this increase in TARC production was significantly inhibited by suplatast tosilate (97.5% inhibition at 100 microg/mL, P < 0.01). CONCLUSION: Suplatast tosilate inhibits TARC production by human Th2 cells. Therefore, this agent inhibits both Th2 cytokine and Th2 chemokine and may be a useful anti-allergic agent.     

Interleukin (IL)-4 and to a lesser extent either IL-13 or interferon-gamma regulate the production of eotaxin-2/CCL24 in nasal polyps

BACKGROUND: Eotaxin-2/CCL24 is a potent eosinophil attractant that has been implicated in the recruitment of eosinophils in allergic disease. We have investigated whether the cytokines interleukin (IL)-4, IL-13, and interferon (IFN)-gamma regulate eotaxin-2/CCL24 in nasal polyps. METHODS: Nasal polyps were cultured in the presence of the cytokines described above and the concentration of eotaxin-2/CCL24 was measured in the culture supernatant. RESULTS: IL-4 was found to be the major stimulus for eotaxin-2/CCL24 production from nasal polyps followed by IL-13 and IFN-gamma. IL-4 induced eotaxin-2/CCL24 in a dose-dependent manner with concentrations as low as 0.1 ng/ml being able to induce eotaxin-2/CCL24. By immunohistochemistry, eotaxin-2/CCL24 immunoreactivity was localized to mononuclear cells in the IL-4 stimulated nasal polyp tissue. Interestingly, nasal turbinates obtained from patients suffering from nonallergic rhinitis (vasomotor rhinitis) were also found to release eotaxin-2/CCL24 both spontaneously and following cytokine stimulation with IL-4 and IFN-gamma being major inducers of this cytokine. CONCLUSIONS: All together these findings suggest that Th1 and Th2 cytokines may regulate eotaxin-2/CCL24 production in nasal polyps and nonallergic rhinits.     

Bradykinin increases the in vivo expression of the CXC chemokine receptors CXCR1 and CXCR2 in patients with allergic rhinitis

BACKGROUND: Increased levels of bradykinin and IL-8 have been detected within the airways of individuals with active symptoms of allergic rhinitis and asthma. OBJECTIVE: We sought to investigate the in vivo effect of bradykinin on the expression of the IL-8 receptors CXCR1 and CXCR2 in nasal cells. METHODS: Nasal samples were obtained from patients with active allergic rhinitis; patients with mild, quiescent allergic rhinitis; and healthy control subjects. CXCR1 and CXCR2 mRNA expression in the nasal cells was measured by means of quantitative real-time RT-PCR in baseline samples from all subjects, as well as in samples obtained after in vivo bradykinin challenge in healthy control subjects and patients with mild allergic rhinitis. CXCR1 and CXCR2 cell-surface expression was also assessed by means of flow cytometry in nasal epithelial cells at baseline and after ex vivo bradykinin challenge. RESULTS: No difference was seen in CXCR1 or CXCR2 mRNA expression between healthy control subjects and patients with quiescent allergic rhinitis at baseline; however, patients with active allergic rhinitis had increased baseline expression of both CXCR1 and CXCR2 mRNA. In vivo nasal bradykinin challenge significantly increased CXCR1 and CXCR2 mRNA expression in patients with quiescent allergic rhinitis but had no effect in healthy control subjects. Low levels of CXCR1 but not CXCR2 cell-surface expression was detected in nasal epithelial cells at baseline, and ex vivo bradykinin challenge induced CXCR2 cell-surface expression in nasal epithelial cells from patients with mild allergic rhinitis. CONCLUSION: This study demonstrates the in vivo regulation of chemokine receptors by means of bradykinin in human airway tissue in patients with allergic rhinitis.     

Histamine alters gene expression in cultured human nasal epithelial cells

BACKGROUND: Airway epithelial cells produce cytokines and participate in the regulation of mucosal immunity. Although nasal epithelial cells express histamine receptors, it is not exactly known how nasal epithelial cells respond to histamine. OBJECTIVE: The objective of this study was to examine whether histamine can alter the expression of the 4 genes encoding H1 receptor, IL-8, TNF-alpha, and ZO-1 tight-junction protein in cultured nasal epithelial cells. METHODS: We added histamine or vehicle to cultured human nasal epithelial cells and extracted RNA from them 4 hours later. After DNase treatment, mRNAs of beta-actin, H1 receptor, IL-8, TNF-alpha, and ZO-1 tight-junction protein were amplified by using RT-PCR. RESULTS: Histamine significantly upregulated IL-8 mRNA expression and significantly downregulated ZO-1 mRNA expression. The latter effect was blocked by pretreatment with mepyramine, an H1 receptor antagonist. CONCLUSION: The reduction of ZO-1 mRNA by histamine may cause increased permeability of the mucosa during allergic reactions in the nose.     

A possible role of TARC in antigen-specific Th2-dominant responses in patients with Paragonimiasis westermani

BACKGROUND: Paragonimiasis westermani (Pw), a common parasitic zoonosis in Asia, is typically associated with eosinophilia. Th2 cytokines seem to have an important role in the clinical manifestations of this disease. Thymus and activation-regulated chemokine (TARC) is a potential key regulator of Th2-mediated inflammation. The purpose of the present study was to evaluate the antigen-specific Th2-dominant responses in patients with Pw. METHODS: The concentrations of cytokines and chemokines in supernatants of peripheral blood mononuclear cell (PBMC) cultures with or without antigen stimulation were measured by enzyme-linked immunosorbent assay (ELISA). TARC levels in serum from Pw patients were also evaluated by ELISA. The number of Th2 cells expressing the CC-chemokine receptor 4 (CCR4) in the peripheral blood was evaluated by flow cytometry. RESULTS: Antigen-stimulation induced production of IL-5 and IL-13, but not IFN-gamma from PBMC cultures in patients with Pw. Pw patients had elevated serum TARC levels and a higher proportion of CCR4-expressing cells among CD4+ T cells in the peripheral blood. There were also higher levels of TARC, but not IP-10, in supernatants of antigen-stimulated PBMC culture compared to unstimulated PBMC culture in patients with Pw. CONCLUSION: Our findings clarify antigen-specific Th2-dominant responses in patients with Pw and suggest a possible role for TARC in Th2-dominant responses.     

Effect of seasonal allergen exposure on mucosal IL-16 and CD4+ cells in patients with allergic rhinitis

BACKGROUND: CD4+ T cells constitute a major source of cytokines in allergic diseases such as allergic rhinitis. Interleukin (IL)-16 selectively recruits CD4+ cells. METHODS: We evaluated the effect of natural allergen exposure during a grass-pollen season on IL-16 expression and number of CD4+ cells in nasal mucosa. Patients with allergic rhinitis (n=16) were treated with either a nasal glucocorticoid beclomethasone (BDP; 400 microg/day) or placebo, and gave nasal biopsies prior to and during the grass-pollen season. The evaluated markers in allergic rhinitis patients were also compared to those in healthy control subjects (n=5). RESULTS: Prior to the pollen season, the expression of IL-16, but not the number of CD4+ cells, was significantly higher in patients with allergic rhinitis than in healthy control subjects. The grass-pollen season further increased IL-16 expression and also increased the number of CD4+ cells in placebo-treated, but not in BDP-treated, allergic rhinitis patients. The pollen-season-induced change in IL-16 expression and in CD4+ cells was significantly more pronounced in placebo- than in BDP-treated patients. There was a significant correlation between the change in IL-16 expression and the number of CD4+ cells. CONCLUSIONS: These data suggest that local upregulation of IL-16 expression contributes to the inflammation observed in seasonal allergic rhinitis. Hypothetically, inhibition of IL-16 expression can be one of several mechanisms by which nasal glucocorticoids achieve their anti-inflammatory effect in allergic rhinitis.     

Inhibition by IL-12 and IFN-alpha of I-309 and macrophage-derived chemokine production upon TCR triggering of human Th1 cells

Th1 and Th2 cells, which produce distinct sets of cytokines, differentially express several chemokine receptors that may regulate their tissue-specific localization. Although the expression pattern and regulation of chemokines are likely to play a critical role in many immunopathological processes, they remain largely unknown. Here, we investigated the requirements for Th1 and Th2 cells to produce the Th2 cell-attracting chemokines thymus and activation-regulated chemokine (TARC), macrophage-derived chemokine (MDC) and I-309. TCR triggering of Th1 and Th2 cells leads to production of MDC and I-309 (CCR4 and CCR8 ligands, respectively), whereas TARC (CCR4 ligand) is selectively produced by Th2 cells. Secretion of these chemokines appears to be independent of endogenous production of IL-4 and IFN-gamma. IL-12 and IFN-alpha, cytokines that promote the differentiation of human Th1 cells, selectively inhibit secretion and mRNA expression of MDC and I-309 by Th1 cells. Suppression of I-309 secretion results in a decreased chemotactic effect on L1.2 cells transfected with human CCR8, indicating that IL-12 and IFN-alpha may inhibit the recruitment of CCR8-expressing cells such as Th2 cells. The inhibition of Th2 cell-attracting chemokines MDC and I-309 illustrates a novel mechanism by which IL-12 and IFN-alpha could promote and maintain an ongoing Th1 response.