Epithelial differentiation is a determinant in the production of eotaxin-2 and -3 by bronchial epithelial cells in response to IL-4 and IL-13

The composition of the airway epithelium is dynamic and epithelial differentiation is regulated by endogenous mediators as well as inhaled substances. In atopic asthma the differentiation of the epithelium is altered. Various studies have addressed the ability of cultured airway epithelial cells to release the eosinophil-attractant chemokines eotaxin, eotaxin-2 and eotaxin-3 using epithelial cell lines or poorly differentiated primary cells. Since little is known about the role of the epithelial differentiation state in the response of epithelial cells to stimuli that increase production of mediators such as the eotaxins, we analyzed the effect of differentiation state on the production of the eotaxins. In particular, we investigated the effects of the Th2 cytokines IL-4 and IL-13 on eotaxin-2 and -3 production by primary human bronchial epithelial cells and examined whether their production is affected by epithelial cell differentiation using both submerged and air-liquid interface (ALI) cultures. The results show that both IL-4 and IL-13 increase eotaxin-2 and -3 mRNA expression and protein release in submerged- and ALI-cultures. Moreover, epithelial differentiation in ALI-cultures appeared an important determinant in the regulation of eotaxin-2 and -3. Mucociliary differentiation of the epithelial cells was induced by culture in the presence of a high concentration of retinoic acid (RA), whereas low concentrations of RA resulted in a flattened squamous epithelial phenotype. Mucociliary differentiated ALI-cultures expressed and released more eotaxin-3 upon stimulation with IL-4/IL-13, whereas eotaxin-2 production was predominantly found in squamous differentiated ALI-cultures. TNFalpha reduced IL-4-induced eotaxin-2 release in submerged cultures but not in ALI-cultures; no effects on eotaxin-3 synthesis were observed. The results indicate that epithelial differentiation is an important determinant in Th2 cytokine-induced eotaxin-2 and -3 release by airway epithelial cells. These findings may provide new insights into the role of airway epithelial differentiation and Th2 cytokines in the pathogenesis of inflammatory lung disorders such as asthma.     

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).     

Oral Lovastatin Attenuates Airway Inflammation and Mucus Secretion in Ovalbumin-Induced Murine Model of Asthma

Purpose

Lovastatin is an effective inhibitor of cholesterol synthesis. A previous study demonstrated that lovastatin can also suppress airway hyperresponsiveness (AHR) in murine model of asthma. We aimed to investigate the effect of lovastatin on mucus secretion and inflammation-associated gene expression in the lungs of murine model of asthma.

Methods

Female BALB/c mice were sensitized and challenged with ovalbumin (OVA) by intraperitoneal injection, and orally administered lovastatin from days 14 to 27 post-injection. Gene expression in lung tissues was analyzed using real-time polymerase chain reaction. AHR and goblet cell hyperplasia were also examined. BEAS-2B human bronchial epithelial cells were used to evaluate the effect of lovastatin on the expression of cell adhesion molecules, chemokines, and proinflammatory cytokines in vitro.

Results

We showed that lovastatin inhibits the expression of Th2-associated genes, including eotaxins and adhesion molecules, in the lungs of murine model of asthma. Mucin 5AC expression, eosinophil infiltration and goblet cell hyperplasia were significantly decreased in the lung tissue of murine model of asthma treated with lovastatin. Furthermore, lovastatin inhibited AHR and expression of Th2-associated cytokines in bronchoalveolar lavage fluid. However, a high dose (40 mg/kg) of lovastatin was required to decrease specific IgE to OVA levels in serum, and suppress the expression of Th2-associated cytokines in splenocytes. Activated BEAS-2B cells treated with lovastatin exhibited reduced IL-6, eotaxins (CCL11 and CCL24), and intercellular adhesion molecule-1 protein expression. Consistent with this, lovastatin also suppressed the ability of HL-60 cells to adhere to inflammatory BEAS-2B cells.

Conclusions

These data suggest that lovastatin suppresses mucus secretion and airway inflammation by inhibiting the production of eotaxins and Th2 cytokines in murine model of asthma.     

Adenoviral interleukin-12 gene transduction into human bronchial epithelial cells: up-regulation of pro-inflammatory cytokines and its prevention by corticosteroids

BACKGROUND: One of the potential effects of IL-12 is to restore Th1/Th2 balance. Therefore, we investigated the possibility of developing a system for local delivery of IL-12 into the airways by examining protein expression in a human bronchial epithelial cell line (BEAS-2B) after adenoviral IL-12 gene transduction. The effects of dexamethasone on the gene-modified cells were also examined. MEHODS: Adenoviral vectors AxCAegfp and Ax1CIhp40ip35 were used to transduce enhanced green fluorescence protein and IL-12 genes, respectively, into BEAS-2B cells. Wild-type and IL-12 gene-transduced BEAS-2B cells were then incubated with or without dexamethasone, and concentrations of IL-12, IFN-gamma, IL-6, IL-8, granulocyte macrophage-colony stimulating factor and chemokines (TARC and RANTES) in the supernatant were measured by ELISA. IL-12 receptor expression was analysed by flow cytometry and RT-PCR. RESULTS: The efficiency of transgene expression in BEAS-2B cells at a multiplicity of infection of 30 was approximately 80%. Gene-modified BEAS-2B cells produced biologically active IL-12, regardless of dexamethasone treatment. While IL-12 gene transduction led to increased production of IL-6 and IL-8 by BEAS-2B cells, expressions of these proteins were suppressed by dexamethasone. Addition of exogenous IL-12 failed to augment BEAS-2B cell IL-6 and IL-8 production, and IL-12 receptor expression by BEAS-2B cells was not detected. CONCLUSIONS: Our findings suggest that adenoviral IL-12 gene transduction may be effective in inducing IL-12 expression in the airways, and could be a potential approach in the management of bronchial asthma.     

Functional characterization of histamine receptor subtypes in a human bronchial epithelial cell line

Histamine is a well-known mediator eliciting a broad range of responses in different cell types. Four different subtypes of G protein-coupled histamine receptors (H1-H4) have been cloned and pharmacologically characterized. However, involvement of the different histamine receptor subtypes in immunomodulatory functions of bronchial epithelium has only been investigated marginally. The expression and function of histamine receptor subtypes on the human bronchial epithelial cell line BEAS-2B was analyzed by PCR, intracellular Ca++ -measurements and ELISA. We show mRNA expression of the histamine receptor subtypes H1, H2, and H3, but not H4 in the human bronchial epithelial cell line BEAS-2B. Using intracellular Ca++ -measurements, we demonstrated functional expression of the H1 and H3 receptors. To characterize the biological properties of histamine in airway epithelial biology, we also investigated its effects on cytokine secretion by BEAS-2B cells. Thereby, we were able to show up-regulation of the proinflammatory mediators IL-6 and CXCL8/ IL-8 via activation of the H1, H2 and H3 receptor subtypes. The Th1 cytokines CXCL9/MIG and CXCL10/IP-10 and the chemokine CCL5/RANTES were regulated in a distinct manner: Whereas histamine inhibited the IFN-gamma/TNF-alpha-induced secretion of MIG via the histamine receptor subtypes H1, H2, and H3, the histamine-induced suppression of RANTES was due to activation of the H2 and H3 receptors, while reduction of cytokine-triggered IP-10 secretion was mediated only by triggering the H2 receptor. In summary our data provide evidence that histamine released during allergic lung diseases exerts regulatory influence on airway epithelial cells.     

Interleukin-12 differentially regulates expression of IFN-gamma and interleukin-2 in human T lymphoblasts.

Interleukin-12 (IL-12) is known to upregulate expression of interferon-gamma (IFN-gamma) by activated T cells. However, the effects of IL-12 on production of other Th1-type cytokines are less well defined. In this study, we examined the effects of IL-12 on expression of several cytokines, including IFN-gamma, IL-2, tumor necrosis factor-alpha (TNF-alpha), and IL-10, by primary human CD3(+) T cells. Although purified resting T cells were largely nonresponsive to IL-12 stimulation, anti-CD3-activated T cell blasts were strongly responsive, as demonstrated by the ability of IL-12 to induce Stat4 DNA-binding activity. Restimulation of T lymphoblasts on immobilized anti-CD3 monoclonal antibodies (mAb) induced rapid expression of TNF-alpha mRNA and more gradual increases in mRNA levels for IL-2, IFN-gamma, and IL-10. IL-12 markedly upregulated expression of IFN-gamma and IL-10 but downregulated expression of IL-2 in a dose-dependent and time-dependent manner. The levels of IL-2 produced by IL-12-treated T cells correlated inversely with the levels of IL-10. Moreover, neutralization of IL-10 activity with anti-IL-10 antibodies normalized IL-2 production by IL-12-treated T cells, confirming that the inhibition of IL-2 production by IL-12 was IL-10 mediated. Thus, IL-12 amplified expression of IFN-gamma and IL-10 and, via its ability to upregulate production of IL-10, inhibited expression of IL-2. These findings demonstrate that IL-12 differentially regulates expression of the Th1-type lymphokines, IFN-gamma and IL-2, in T lymphoblasts.     

Dehydroepiandrosterone Suppresses Eosinophil Infiltration and Airway Hyperresponsiveness via Modulation of Chemokines and Th2 Cytokines in Ovalbumin-Sensitized Mice

In this study, we evaluated the anti-inflammatory response and the mechanism by which dehydroepiandrosterone modulates immunity in ovalbumin-sensitized asthmatic mice. Female BALB/c mice were sensitized and challenged with ovalbumin and then treated with oral administration of dehydroepiandrosterone on days 21 to 27. The results showed dehydroepiandrosterone could suppress airway hyperresponsiveness and decrease eosinophil infiltration of the lungs in ovalbumin-sensitized mice. Moreover, dehydroepiandrosterone inhibited chemokines, including CCL11/eotaxin-1 and CCL24/eotaxin-2, and Th2-associated cytokine levels in bronchoalveolar lavage fluid. After the inflammatory human bronchial epithelial cell line BEAS-2B was treated with dehydroepiandrosterone, levels of proinflammatory cytokines and chemokines were inhibited, including IL-6, IL-8, CCL11, and CCL24. We suggested that dehydroepiandrosterone inhibited inflammation in bronchial epithelial cells as indicated by the suppression of Th2-associated cytokines and chemokines. Dehydroepiandrosterone also suppressed eosinophil migration and infiltration into the lung to improve the symptoms of asthma in ovalbumin-sensitized mice.     

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.     

Interleukin-4 regulates the interleukin-2 receptors on human peripheral blood B lymphocytes.

The high-affinity interleukin-2 (IL-2) receptor (IL-2R) consists of the non-covalent association of at least two subunits, p55 and p70-75, capable of binding IL-2 with low and intermediate affinity, respectively. We studied the effects of cytokines on the IL-2R expressed on human peripheral blood B lymphocytes using monoclonal antibodies specific for IL-2R p55 and IL-2R p70-75, by means of two-colour flow cytometric analysis. In freshly isolated peripheral blood B lymphocytes, the p55 subunit was expressed only in a small population (7.0% of CD20+ cells), whereas the p70-75 subunit was expressed in a large population (89.0% of CD20+ cells). Of the cytokines studied, interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) were involved in the regulation of IL-2R on B cells. After a 2-day incubation with IL-4, expression of IL-2R p55 was markedly induced, but expression of IL2-R p70-75 was profoundly suppressed in a dose-dependent manner. These abilities of IL-4 to promote IL-2R p55 expression and suppress IL-2R p70-75 expression were inhibited by the presence of IFN-gamma. Other cytokines, including IL-1, IL-2, IL-5, and IL-6, had little effect on the expression of these two subunits. These findings suggest that IL-4 is a cytokine modulating B cell response through the regulation of IL-2R.     

Human peripheral blood CD4+ and CD8+ T cells express Th1-like cytokine mRNA and proteins following in vitro stimulation with heat-inactivated Brucella abortus.

Defining the pattern of lymphokine production associated with Brucella abortus is critical for advancing the development of B. abortus as a vaccine carrier. In the present study we investigated the ability of heat-inactivated B. abortus or lipopolysaccharide from B. abortus to induce lymphokine production from purified human T cells in vitro. Gamma interferon (IFN-gamma), interleukin-2 (IL-2), IL-4, and IL-5 induction was assayed by mRNA-specific PCR and by enzyme-linked immunosorbent assay and bioassay for protein production. Following depletion of monocytes and B cells, B. abortus increased IFN-gamma and IL-2 mRNA expression in purified T cells compared with expression in unstimulated cells. In contrast, no IL-5 mRNA expression and only transient low-level IL-4 mRNA expression and no IL-4 protein secretion were detected. Phytohemagglutinin or phorbol myristate acetate plus ionomycin induced mRNA and protein for all these cytokines. Similar results were obtained with LPS purified from B. abortus. Removal of NK cells did not reduce lymphokine production, and enriched NK cells did not express IFN-gamma mRNA or secrete IFN-gamma protein in response to B. abortus, indicating that NK cells were not the responding population. Both CD4+ and CD8+ populations produced IFN-gamma and IL-2 in response to B. abortus. Preincubation of resting T cells with B. abortus or LPS from B. abortus for 7 days induced their differentiation into Th1-like cells as judged by their subsequent lymphokine response to phorbol myristate acetate plus ionomycin. These results suggest that B. abortus can induce differentiation of Th0 into Th1-type cells.