Diesel exhaust particulates upregulate histamine receptor mRNA and increase histamine-induced IL-8 and GM-CSF production in nasal epithelial cells and endothelial cells.

BACKGROUND: Histamine is the most important chemical mediator in the pathogenesis of nasal allergy. Diesel exhaust particulates (DEPs) are common air pollutants from diesel engine-powered car exhaust and cause chronic airway diseases. Recently we observed that the nasal reactivity to histamine was enhanced in diesel exhaust-exposed guinea-pigs. It was also revealed that epithelial cells and endothelial cells in the airway produce certain cytokines in response to histamine. OBJECTIVE: We examined the effects of DEP extract on the expression of histamine H1 receptor (H1R) mRNA in human nasal epithelial cells (HNECs) and human mucosal microvascular endothelial cells (HMMECs), and on the production of IL-8 and GM-CSF induced by histamine. METHODS: HNECs and HMMECs were isolated from human nasal mucosa specimens. HNEC and HMMEC monolayers were cultured in the presence or absence of DEP extract. The change in the expression of H1R mRNA was then evaluated by reverse transcriptase-polymerase chain reaction (RT-PCR) and the Southern blot analysis. To investigate the effects of DEP extract on the histamine-induced cytokine production, HNEC and HMMEC monolayers were cultured in the presence or absence of DEP extract for 3-24 h. After three washes with PBS, they were then incubated with 10(-6) mol/L histamine for 24 h. The amounts of IL-8 and GM-CSF in the culture media were measured by enzyme-linked immunoabsorbent assay. RESULTS: DEP extract increased the expression of H1R mRNA in both HNECs and HMMECs. The amount of IL-8 and GM-CSF, induced by histamine, was significantly higher in DEP extract pretreated HNECs and HMMECs than nontreated HNECs and HMMECs. CONCLUSION: These results strongly suggest that DEP accelerates the inflammatory change by not only directly upregulating H1R expression but also increasing histamine-induced IL-8 and GM-CSF production.

Effect of female hormones on the production of IL-4 and IL-13 from peripheral blood mononuclear cells.

In this study we compared the concentrations of IL-4, IL-13, and IFN-gamma, which were produced by human peripheral blood mononuclear cells (PBMC) in the presence or absence of preincubation with beta-estradiol or progesterone both after a specific antigen challenge and without a specific antigen challenge. The concentrations of IL-4 and IL-13 from PBMC which had been preincubated with progesterone or gamma-estradiol for 18-24 h were significantly greater than those of IL-4 and IL-13 from PBMC which had been preincubated with PBS, the control. On the other hand, the concentration of IFN-gamma from PBMC was unchanged. We were able to confirm that the female hormones beta-estradiol and progesterone, at levels similar to those occurring during pregnancy, have the ability to induce production of IL-4 and IL-13 in human mononuclear cells. These results suggest that female hormones may aggravate nasal allergy symptoms during pregnancy by increasing IgE synthesis and inducing selective eosinophil infiltration.

The potential role of interleukin-13 in eosinophilic inflammation in nasal mucosa.

BACKGROUND: Recent studies have revealed that interleukin (IL)-13, as well as IL-4, causes de novo surface expression of vascular cell adhesion molecule-1 (VCAM-1) on endothelial cells of the umbilical vein and accelerates selective eosinophil migration. However, its role in allergic rhinitis remains to be clarified. Of particular interest is whether IL-13 upregulates VCAM-1 expression in human mucosal microvascular endothelial cells (HMMECs), to which eosinophils adhere in nasal mucosa. METHODS: To understand the potential role of IL-13 in eosinophilic inflammation in nasal mucosa, we examined the effects of IL-13 on the adhesiveness between HMMECs and eosinophils. RESULTS: IL-13 increased VCAM-1 expression in HMMECs, the adhesiveness of endothelial cells to eosinophils, and the transendothelial migration. On the other hand, IL-13 decreased the adhesiveness of eosinophils to HMMECs, and, as a result, accelerated eosinophil infiltration. Those effects are more potent than was those of IL-4. In addition, we also report that the amount of IL-13 in nasal mucosa was higher than that of IL-4. CONCLUSIONS: These results strongly indicate that IL-13, as well as IL-4, may be important in eosinophilic inflammation in the nasal mucosa.

Late phase response in nasal mucosa closely correlated with immediate phase reaction and hyperreactivity to histamine.

It has been suggested that the onset of the late phase response (LPR) and hyperreactivity to non-specific stimuli occurs in the lower airway. However, its relationship in the nose has not yet been studied. This study was designed to examine the mechanism of LPR and the relationship between LPR and hyperreactivity. A total of 25 Japanese cedar pollinosis patients participated in this study. On the first visit, the frequency of sneezes, weight of nasal discharge, and the nasal airway resistance (NAR) were time-dependently measured without antigen challenge. The histamine reactivity was observed after 12 h. The same protocol was used during the second to fourth visits. The frequency of sneezes, weight of nasal discharge, and NAR were measured continuously for 12 h after antigen challenge, and nasal reactivity to histamine was observed. The percent change of NAR during immediate phase response (IR) and during LPR showed a significant correlation. The frequency of sneezes and weight of nasal discharge induced by histamine were both significantly higher in the positive than in the negative LPR group. These results suggest that the chemical mediators and inflammatory cells inducing nasal swelling during IR cause, directly or indirectly, nasal swelling during LPR, and induce hyperreactivity to histamine.

The effects of eotaxin on the surface adhesion molecules of endothelial cells and on eosinophil adhesion to microvascular endothelial cells.

Eosinophil recruitment occurs in tissues as the result of allergic diseases. Human eotaxin is thought to be specific to eosinophils. In this study, we examined the effects of human eotaxin on the expression of adhesion molecules on nasal microvascular endothelial cells and on eosinophil adhesion to endothelial cells. Eotaxin upregulated the expression of ICAM-1 and VCAM-1 on human nasal mucosal microvascular endothelial cells (HMMEC), but not human umbilical vein endothelial cells (HUVEC). The eotaxin-induced eosinophil adhesion to HMMEC was increased at 10 ng/ml and significantly increased at the concentration of 100 ng/ml. On HUVEC, however, eotaxin did not induce increases of eosinophil adhesion. Anti-ICAM-1 and anti-VCAM-1 mAbs significantly decreased eotaxin-induced eosinophil adhesion. These results suggest that eotaxin regulates eosinophil accumulation to the nasal mucosa through its effect on the adhesion molecules on microvascular endothelial cells.