Interleukin-33 induces interleukin-17F in bronchial epithelial cells

BACKGROUND

IL-33 is clearly expressed in the airway of patients with asthma, but its role in asthma has not yet been fully understood. IL-17F is also involved in the pathogenesis of asthma. However, the regulatory mechanisms of IL-17F expression remain to be defined. To further indentify the role of IL-33 in asthma, we investigated the expression of IL-17F by IL-33 in bronchial epithelial cells and its signaling mechanisms.

METHODS

Bronchial epithelial cells were stimulated with IL-33. The levels of IL-17F expression were analyzed using real-time PCR and ELISA. Next, the involvement of ST2, MAP kinases, and mitogen- and stress-activated protein kinase1 (MSK1) was determined by Western blot analyses. Various kinase inhibitors and anti-ST2 neutralizing Abs were added to the culture to identify the key signaling events leading to the expression of IL-17F, in conjunction with the use of short interfering RNAs (siRNAs) targeting MSK1.

RESULTS

IL-33 significantly induced IL-17F gene and protein expression. The receptor for IL-33, ST2, was expressed in bronchial epithelial cells. Among MAP kinases, IL-33 phosphorylated ERK1/2, but not p38MAPK and JNK. It was inhibited by the pretreatment of anti-ST2 neutralizing (blocking) Abs. MEK inhibitor significantly blocked IL-17F production. Moreover, IL-33 phosphorylated MSK1, and MEK inhibitor diminished its phosphorylation. Finally, MSK1 inhibitors and transfection of the siRNAs targeting MSK1 significantly blocked the IL-17F expression.

CONCLUSIONS

IL-33 induces IL-17F via ST2-ERK1/2-MSK1 signaling pathway in bronchial epithelial cells. These data suggest that the IL-33/IL-17F axis is involved in allergic airway inflammation and may be a novel therapeutic target.

Induction of insulin-like growth factor-I by interleukin-17F in bronchial epithelial cells

BACKGROUND

Increased expression of IL-17F has been noted in the airway of asthmatic patients, but its role in asthma has not been fully elucidated. Insulin-like growth FACTOR-I (IGF-I) is known to be involved in airway remodelling and inflammation, while its regulatory mechanisms remain to be defined.

OBJECTIVE

To further clarify the biological function of IL-17F, we investigated whether IL-17F is able to regulate the expression of IGF-I in bronchial epithelial cells.

METHODS

Bronchial epithelial cells were stimulated with IL-17F in the presence or absence of T-helper type 2 cytokines. Various kinase inhibitors were added to the culture to identify the key signalling events leading to the expression of IGF-I, in conjunction with the use of short interfering RNAs (siRNAs) targeting mitogen- and stress-activated protein kinase (MSK) 1, p90 ribosomal S6 kinase (p90RSK), and cyclic AMP response element-binding protein (CREB).

RESULTS

IL-17F significantly induced IGF-I gene and protein expression, and co-stimulation with IL-4 and IL-13 augmented its production. MAP kinase kinase (MEK) inhibitors and the Raf1 kinase inhibitor significantly inhibited IGF-I production, and the combination of PD98059 and Raf1 kinase inhibitor showed further inhibition. Overexpression of Raf1 and Ras dominant-negative mutants inhibited its expression. MSK1 inhibitors significantly blocked IL17F-induced IGF-I expression. Moreover, transfection of the siRNAs targeting MSK1, p90RSK, and CREB blocked its expression.

CONCLUSIONS

In bronchial epithelial cells, IL-17F is able to induce the expression of IGF-I via the Raf1-MEK1/2-ERK1/2-MSK1/p90RSK-CREB pathway in vitro.

Transforming growth factor-β stimulates the expression of eotaxin/CC chemokine ligand 11 and its promoter activity through binding site for nuclear factor-κβ in airway smooth muscle cells

BACKGROUND

Chemokines ligands of CCR3 including eotaxin/CC chemokine ligand 11 (CCL11) may contribute to the pathogenesis of asthma. These chemokines and a growth factor (TGF-beta) may be involved in the process of airway remodelling.

OBJECTIVE

We analysed the effects of TGF-beta on the expression of CCR3 ligands in human airway smooth muscle (HASM) cells and investigated the mechanisms.

METHODS

HASM cells were cultured and treated with TGF-beta and Th2 cytokines IL-4 or IL-13. Expression of mRNA was analysed by real-time PCR. Secretion of CCL11 into the culture medium was analysed by ELISA. Transcriptional regulation of CCL11 was analysed by luciferase assay using CCL11 promoter-luciferase reporter plasmids.

RESULTS

IL-4 or IL-13 significantly up-regulated the expression of mRNAs for CCL11 and CCL26. TGF-beta alone did not increase the expression of chemokine mRNAs, but enhanced the induction of only CCL11 by IL-4 or IL-13 among CCR3 ligands. Activity of the CCL11 promoter was stimulated by IL-4, and this activity was enhanced by TGF-beta. Activation by IL-4 or IL-4 plus TGF-beta was lost by mutation of the binding site for signal transducers and activators of transcription-6 (STAT6) in the promoter. Cooperative activation by IL-4 and TGF-beta was inhibited by mutation of the binding site for nuclear factor-kappaB (NF-kappaB) in the promoter. Pretreatment with an inhibitor of NF-kappaB and glucocorticoid fluticasone propionate significantly inhibited the expression of CCL11 mRNA induced by IL-4 plus TGF-beta, indicating the importance of NF-kappaB in the cooperative activation of CCL11 transcription by TGF-beta and IL-4.

CONCLUSION

These results indicate that Th2 cytokines and TGF-beta may contribute to the pathogenesis of asthma by stimulating expression of CCL11. The transcription factors STAT6 and NF-kappaB may play pivotal roles in this process.

Synthetic double-stranded RNA induces multiple genes related to inflammation through Toll-like receptor 3 depending on NF-kappaB and/or IRF-3 in airway epithelial cells

BACKGROUND

We hypothesized that synthetic double-stranded (ds)RNA may mimic viral infection and induce expression of genes related to inflammation in airway epithelial cells.

OBJECTIVE

We analysed what gene was up-regulated by synthetic dsRNA poly I : C and then focused this study on the role of Toll-like receptor 3 (TLR3), a receptor of dsRNA and its transcriptional pathway.

METHODS

Airway epithelial cell BEAS-2B and normal human bronchial epithelial cells were cultured in vitro. Expression of targets RNA and protein were analysed by PCR and ELISA. Localization of TLR3 expression in the cells was analysed with flow cytometry. To analyse the role of TLR3 and transcription factors, knockdown of these genes was performed with short interfering RNA (siRNA).

RESULTS

Real-time PCR revealed that poly I : C significantly increased the expression of mRNAs for chemokines IP-10, RANTES, LARC, MIP-1alpha, IL-8, GRO-alpha and ENA-78 and cytokines IL-1beta, GM-CSF, IL-6 and the cell adhesion molecule ICAM-1 in both cell types. Increases in protein levels were also observed. Expression of these genes was significantly inhibited in BEAS-2B cells in which TLR3 expression was knocked down. However, pre-treatment with anti-TLR3 mAb, which interferes with the function of TLR3 expressed on the cell surface, did not inhibit the genes expression and these data were concordant with the results that TLR3 was expressed inside airway epithelial cells. The study of siRNA for NF-kappaB and IRF3 showed that they transduce the signal of poly I : C, but their roles were different in each target gene.

CONCLUSION

TLR3 is expressed inside airway epithelial cells and transduces synthetic dsRNA signals. These signals may increase expression of inflammatory cytokines, chemokines and ICAM-1 through activation of transcription factors NF-kappaB and/or IRF3 in airway epithelial cells.

Double-stranded RNA activates RANTES gene transcription through co-operation of nuclear factor-kappaB and interferon regulatory factors in human airway epithelial cells

BACKGROUND

Regulated on activation, normal T cells expressed and secreted (RANTES) is a member of the CC chemokine family and contributes to viral-induced airway inflammation including exacerbations of asthma. Double-stranded RNA (dsRNA) is known to be synthesized during replication of many viruses and a ligand of Toll-like receptor 3. We hypothesized that dsRNA may mimic viral infection and induce RANTES expression in airway epithelial cells.

OBJECTIVE

We first confirmed that dsRNA up-regulated RANTES mRNA and protein synthesis in the airway epithelial cells. We next focused our studies on the transcriptional regulation of RANTES.

METHODS

Airway epithelial cell line BEAS-2B and normal human bronchial epithelial cells were used in vitro study. Levels of RANTES mRNA and protein expression were determined with RT-PCR and ELISA. Mechanisms of transcriptional regulation were assessed by electrophoretic mobility shift assay and dual luciferase assay using RANTES promoter-luciferase reporter plasmids.

RESULTS

Activation of nuclear factor-kappaB (NF-kappaB) was confirmed by nuclear protein binding to a DNA probe derived from the RANTES promoter. Activity of the RANTES promoter was increased by dsRNA. The stimulation with dsRNA was partially inhibited in plasmids mutated at either of the binding sites for NF-kappaB or IFN regulatory factors (IRFs). When both sites were mutated, the activation was totally abrogated.

CONCLUSION

These results imply that dsRNA activates NF-kappaB and IRFs and these transcription factors activate transcription of the RANTES promoter and its protein expression in airway epithelial cells.

Modulation of bronchial epithelial cells by IL-17

BACKGROUND

The induction of epithelial cytokines/chemokines is crucial in the migration of leukocytes, and its regulatory mechanisms remain incompletely defined.

OBJECTIVE

To determine the role of IL-17, a CD4(+) T cell-derived cytokine, in modulation of primary bronchial epithelial cells, the expression of IL-6, IL-8, and intercellular adhesion molecule 1 (ICAM-1) and the potential involvement of mitogen-activated protein (MAP) kinases in IL-17-mediated signaling were examined.

METHODS

The levels of gene expression and protein production for IL-6 and IL-8 in IL-17-treated cells, in the presence or absence of MAP kinase inhibitors, were analyzed by RT-PCR and ELISA, respectively, and activation of MAP kinases was determined by Western blot analyses.

RESULTS

We showed first that IL-17 induced time-dependent expression of IL-6 and IL-8 but not of the chemokines eotaxin and RANTES. In addition, IL-17 induced activation of extracellular signal-regulated kinase 1/2 but not of p38 or JNK kinases. A selective MAP kinase kinase inhibitor, PD98059, inhibited IL-17-induced IL-6 and IL-8. A combination of IL-17 and each of the cytokines IL-4, IL-13, and IFN-gamma further enhanced IL-8 expression. IL-17 alone did not induce ICAM-1 expression and showed no effect on IL-4- or IL-13-induced ICAM-1 expression. In contrast, a combination of IL-17 and IFN-gamma augmented IL-6 and ICAM-1 expression.

CONCLUSION

These findings suggest that IL-17, alone or in combination with other cytokines, modulates airway inflammation via-in part-the expression of epithelial IL-6, IL-8, and ICAM-1.

Influenza virus A stimulates expression of eotaxin by nasal epithelial cells

BACKGROUND

Respiratory virus is one of the most common causes of airway inflammation, but its pathogenic mechanisms are not well understood. Eotaxin is a potent eosinophil chemoattractant and is a selective agonist for C-C chemokine receptor 3 (CCR3). Although it has recently been demonstrated that epithelial cells express eotaxin, both in vivo and in vitro, there are few data concerning the expression in viral infection.

OBJECTS

We hypothesized that eotaxin may play an important role in attracting inflammatory cells into the airway after viral infection and analysed whether viral infection induces eotaxin in nasal epithelial cells in vitro.

METHODS

Nasal epithelial cells obtained from polypectomy for nasal polyp were infected with influenza virus A (subtype H3N2). The cells and supernatants were collected 8, 24 and 48 h after infection. Eotaxin mRNA was analysed by RT-PCR. Eotaxin concentration in the supernatants was analysed by enzyme-linked immunosorbent assay. We also examined a blocking assay to analyse the intervention of pro-inflammatory cytokines, TNF-alpha and IL-1beta in eotaxin production induced by influenza virus.

RESULTS

The results showed that eotaxin was expressed constitutively in uninfected cells, but was up-regulated for both mRNA and protein levels in infected cells. Blocking experiments using anti-TNF-alpha and anti-IL-1beta antibodies showed no effects of these agents on the level of eotaxin. In addition, UV-inactivated virus did not enhance the expression of eotaxin.

CONCLUSIONS

These results suggest that influenza virus A infection in nasal epithelial cells stimulates the expression of eotaxin, and may play an important role in the pathogenesis of airway inflammation by inducing eotaxin.

Expression of eotaxin by normal airway epithelial cells after influenza virus A infection

BACKGROUND

Viral infection is known to cause lung inflammatory disease, including bronchial asthma. The mechanisms of inflammatory cell accumulation into the airways after viral infection are not well understood. Eotaxin is a CC chemokine which is a potent and specific agonist for CC chemokine receptor 3 (CCR3). CCR3 is expressed on eosinophils, basophils and T lymphocytes. These cells are known to be key cells in the pathogenesis of asthma. Although it has recently been demonstrated that airway epithelial cells express eotaxin in vivo and in vitro, there are few data about its epxression in viral infection. We hypothesized that eotaxin may play an important role in attracting inflammatory cells to the airways after viral infection, and analyzed whether viral infection attracts eotaxin in bronchial epithelial cells in vitro.

METHODS

Human airway epithelial cells obtained from bronchial tissue at lobectomy for lung cancer were infected with influenza virus A (subtype H3N2). The cells and cultured media were collected 8, 24, and 48 h after infection. Eotaxin mRNA was analyzed with reverse transcriptase-polymerase chain reaction. Eotaxin protein levels in the culture media were analyzed by enzyme-linked immunosorbent assay. We also studied a blocking assay to analyze the intervention of proinflammatory cytokines in its production induced by influenza virus.

RESULTS

Eotaxin mRNA appeared to be expressed constitutively in uninfected cells but was expressed more clearly in infected cells. Eotaxin protein release into culture media significantly increased after infection. Anti-TNF-alpha and anti-IL-1beta antibodies did not alter the eotaxin protein levels after viral infection.

CONCLUSIONS

These results suggest that influenza virus A infection in airway epithelial cells activates the expression of eotaxin and that eotaxin may participate in the pathogenesis of airway inflammatory disease caused by viral infection, such as infectious type asthma.

[The correlation between the exacerbation of bronchial asthma and picornavirus (human rhino virus) infection in throat gargles by RT-PCR]

Viral infection is one of important factors to cause the exacerbation of bronchial asthma. We have investigated 167 adults of asthmatics to clarify the correlation between viral infection and exacerbation of asthma. Patients were classified to four group by the symptoms of common cold and asthma attack. Furthermore, we have examined Picornavirus and Human rhino virus RNA from throat gargles of patients using RT-PCR (reverse transcription--polymerase chain reaction) method. Forty of 65 (61.5%) asthmatics with common cold revealed asthma attack and common cold was significantly associated with acute exacerbation of asthma (p < 0.01). We identified Picornavirus RNA, which include 113 of Human rhino virus serotypes and enterovirus, from the samples of 16 of 52 (30.8%) patients who had acute exacerbation. It was significantly higher than the detection rate of viral RNA from patient without asthma attack. Furthermore, we analyzed Human rhino virus RNA from the same samples by RT-PCR and 93.7% of Picornavirus were identified as Human rhino virus. Taken together, these findings suggest that common cold is significantly associated with the exacerbation of bronchial asthma. Human rhino virus infection might be one of important virus in this procedure.

[Hospitalization reduction by an asthma tele-medicine system]

We examined an effectiveness of a new asthma telemedicine system in reducing hospitalizations using a multi-site randomized control study. In this program, a nurse under physician supervision monitors the patient's airway status at home and provides instructions to individuals via the telephone, helping them manage exacerbations as well as reinforcing proper use of a zone-controlled management plan. Patients with a high risk for hospitalization were screened based on the numbers of emergency room visits and hospitalizations found in a previous study and randomly assigned to either the telemedicine or control group. After a six-month study period, an 83% reduction in hospitalization was demonstrated in the telemedicine group versus the control group, with a P value of 0.01. Improvement of peak expiratory flow and symptoms were also shown in the study group. We conclude that the key success factors in home asthma management for poorly controlled asthma patients are early detection of exacerbations through daily peak flow monitoring, compliance with prescribed daily prophylactic anti-inflammatory steroid medications, and immediate action as specified by a zone-controlled action plan upon the first signs of deterioration.

[Effect of IL-17 on ICAM-1 expression of human bronchial epithelial cells, NCI-H 292]

Bronchial asthma is characterized as a chronic inflammation of the airway infiltrated by eosinophils, lymphocytes, and neutrophils. ICAM-1 expression on airway epithelium facilitates adhesion between these inflammatory cells and bronchial epithelial cells, and induces the activation of inflammatory cells. ICAM-1 expression was affected by various cytokines, such as IL-17. IL-17 is a novel cytokine released by CD4+ activated memory T cells. In this study, we examined the effect of IL-17 on ICAM-1 expression by RT-PCR and flow cytometry. Human bronchial epithelial cells, NCI-H 292 cells, were stimulated with IL-17 (100 ng/ml) and/or IFN-gamma (100 U/ml). ICAM-1 was expressed constitutively. IL-17 alone did not enhance ICAM-1 expression on NCI-H 292 cells. However, IL-17 synergistically enhanced ICAM-1 expression induced by IFN-gamma. These results suggest that IL-17 has an effect on ICAM-1 expression of bronchial epithelial cells in airway inflammation.

[Tele-medicine system for high-risk asthmatic patients]

We have developed a tele-medicine system to monitor the airway status at home for patients with poorly controlled asthma, whereby a nurse provides instructions to individuals via the telephone to help them manage exacerbation under the supervision of their physicians. We examined the effectiveness of this system with a randomized control study. Patients with high hospitalization risk were enrolled in the study by screening patients for those with multiple previous emergency room visits and randomly assigned to either the tele-medicine or control group. After six months of participation in the program, the number of emergency room visits decreased significantly and the activities of daily living were improved in the tele-medicine group. Most of the patients in the tele-medicine group were able to continue measuring and transmitting peak expiratory flow (PEF) value successfully, and at six months had noticed an improvement in PEF. We therefore conclude that the system effectively contributes to the management of poorly controlled asthma. In addition, further consideration suggests that the reduction of emergency room visits may lead to reduction in hospitalization since we found a good correlation between number of emergency room visits and hospitalization from the studies published previously.

IL-10 induces a Th2 cell tolerance in allergic asthma

BACKGROUND

Interleukin (IL)-10 induces a long-term antigen-specific anergy in human CD4+ T cells.

METHODS

Peripheral blood mononuclear cells (PBMCs) were isolated from house dust mite (Dermatophagoides farinae, Der f)-sensitized asthmatic patients. PBMCs were stimulated with Der f antigen for 72 h immediately after purification or after 48 h of resting culture with medium, and IL-10 and IL-5 in the culture supernatant were measured. PBMCs were also stimulated with Der f antigen for 7 days either immediately after purification or after 48 h of resting culture, after which cells were collected. Secondary proliferative responses of these cells to stimulation for 3 days with Der f antigen and mitomycin C-treated PBMCs as antigen-presenting cells or with phorbol myristate acetate (PMA) plus calcium ionophore were investigated.

RESULTS

Stimulation of PBMCs with Der f antigen immediately after purification significantly increased the proliferative response and IL-5 production. Stimulation of PBMCs with Der f antigen after resting culture with medium alone for 48 h significantly decreased IL-5 production and markedly increased IL-10 production. Although activation of cells with Der f antigen immediately after purification significantly increased secondary proliferative responses, stimulation after 48 h of resting culture failed to increase secondary proliferative responses. However, proliferation recovered when cells were activated with PMA plus calcium ionophore.

CONCLUSION

These results suggest that antigen-specific Th2 cells are anergized by IL-10 and that Th2 cell tolerance may suppress eosinophilic inflammation in allergic asthma.

[Effect of slow-release theophylline on airway inflammation in bronchial asthma]

Theophylline has been used as a bronchodilator in acute and chronic asthma management but recent evidences suggest that it has anti-inflammatory effects. Therefore, we investigated the therapeutic effect of slow-release theophylline in mild to moderate asthmatic patients. Symptomatic 19 patients with mild asthma who were treated with inhaled beta 2-agonist alone, and 17 subjects with moderate asthma who were treated with moderate dose of inhaled corticosteroid (beclomethasone dipropionate, BDP, 400-800 micrograms/day) were enrolled to the present study. After two-week run-in period, slow-release theophylline was administered for six to eight weeks and asthma symptoms, respiratory function, airway inflammation evaluated by the inhalation of hypertonic saline, and airway reactivity to histamine were investigated during observation period and after treatment. Asthma symptom score was significantly improved after theophylline treatment in both groups. Morning peak expiratory flow was significantly elevated but FEV1 was not significantly improved by the additional treatment with slow-release theophylline in both groups. Significant decreases in the percentages of total and EG2 + eosinophils in induced sputum demonstrated that slow-release theophylline has anti-inflammatory effect in patients with asthma despite the treatment with inhaled corticosteroid. Because recent reports suggest that theophylline may act as an anti-inflammatory drug even in low dose concentration, we also investigated the effect of plasma theophylline concentration on the airway inflammation. Patients were divided into two groups by the plasma concentration of theophylline, more than 10 micrograms/mL which is necessary to dilate airway and below 10 micrograms/mL, referred to as low dose concentration of theophylline. The results suggest that the administration of slow-release theophylline significantly decreased the percentages of both total and EG2 + eosinophils in induced sputum in both concentration groups. However, airway reactivity to histamine did not significantly change by the treatment. Taken together, we conclude that low dose treatment of slow-release theophylline has an anti-inflammatory effect and treatment with slow-release theophylline alone or the additional use with inhaled corticosteroid is an effective therapy for the management of mild to moderate asthma.

Expression of RANTES by normal airway epithelial cells after influenza virus A infection

The chemokine regulated on activation, normal T cells expressed and secreted (RANTES), is a C-C chemokine and a potent chemoattractant for monocytes, T lymphocytes, basophils, and eosinophils. Its expression by human airway epithelium has been demonstrated both in vitro and in vivo. We investigated whether RANTES is expressed by normal human airway epithelial cells after influenza viral infection and examined its bioactivity. Epithelial cells were obtained from bronchial tissue or nasal polyps of patients who had undergone lobectomy for lung cancer or polypectomy for nasal polyps. These cells were cultured by the outgrowth method. Cultured cells were infected with influenza virus A (subtype H3N2) after which the supernatants and the cells were collected 8 to 72 h after infection. RANTES mRNA (messenger RNA) was analyzed by the reverse transcriptase-polymerase chain reaction and Southern blot analysis of its product. Concentrations of RANTES in the supernatants were analyzed by enzyme-linked immunosorbent assay. RANTES protein and mRNA were not detected in the media of uninfected cells. PCR products for RANTES were clearly detected in nasal and bronchial epithelial cells 24 h after infection. Southern blot analysis confirmed that the PCR products were indeed specific for RANTES mRNA. Twenty-four to 72 h after infection, significant levels of RANTES protein were detected in culture media. We also investigated the chemotactic activity of the supernatant of cultured cells. The supernatant of the cells 48 h after infection had potent chemotactic activity for eosinophils, which was attenuated by the addition of anti-RANTES antibodies. These findings suggest that influenza virus infection may induce expression of bioactive RANTES by normal human bronchial and nasal epithelial cells.

Evaluation of emphysema in patients with reversible airway obstruction using high-resolution CT

OBJECTIVE

This study was carried out to determine whether asthma affects the development of emphysema.

METHODS

We studied 62 patients with reversible airway obstruction during remission, and evaluated the presence and severity of emphysema using high-resolution CT. The emphysema score (ES) was evaluated with the visual scoring method on CT scans.

RESULTS

Of the 62 patients, 14 were judged to have emphysema. Patients with emphysema were significantly older and more likely to be male than those without emphysema. All patients with emphysema were smokers. There was no significant difference in the duration or severity of asthma between patients with and without emphysema. The 62 patients were divided into three groups according to the ES: 48 patients without emphysema (ES = 0%), 8 patients with mild emphysema (0% < ES < 15%), and 6 patients with more severe emphysema (ES > or = 15%). Highly significant differences between patients without emphysema and those with more severe emphysema were found in FEV1 (p<0.01), FEV1/FVC (p<0.001), diffusing capacity for carbon monoxide (DCO) (p<0.01), and DCO/alveolar volume (p<0.0001).

CONCLUSION

Neither the duration nor the severity of asthma was correlated with the presence of emphysema, while smoking history, sex, and age were strongly correlated. No patients with emphysema were found among the nonsmokers, including those with severe asthma or asthma of long duration. These results suggest that asthma does not lead to emphysema.

Induction of apoptosis in human eosinophilic leukemic cell line (EOL-1)

Exposure of human eosinophilic leukemic EOL-1 cells to H2O2, ascorbic acid derivatives, actinomycin D, low-molecular-weight polyphenols, UV irradiation, or hyperthermia resulted in nuclear fragmentation, but failed to induce internucleosomal DNA cleavage. The findings suggest that internucleosomal DNA fragmentation is not a universal biochemical hallmark of apoptosis. Removal of Ca2+ ions from the culture medium significantly reduced the cytotoxic activity of sodium ascorbate, but not that of H2O2. H2O2 significantly elevated the intracellular Ca2+ concentration, with or without Ca2+ in the culture medium. This suggests that sodium ascorbate and H2O2 initiate cell death by different mechanisms. Induction of apoptosis in in vitro systems might be useful in studying the pathogenesis of allergy or asthma.

[Chemotactic activity of human peripheral eosinophils toward leukotriene E4]

We studied the chemotactic activity of isolated human peripheral eosinophils toward leukotriene (LT) E4. We obtained eosinophil suspensions by the method of CD16 negative selection. Eosinophil chemotactic activities toward platelet activating factor (PAF, 10(-6) M) and LTE4 (10(-7) M, 10(-6) M, 10(-5) M) were studied using a modified Boyden Chamber method. Eosinophils migrated significantly toward PAF and LTE4 (10(-7) M, 10(-6) M). The chemotactic activity toward LTE, was most potential at 10(-6) M. These results suggest that LTE4 is an eosinophil chemoattractant.

Expression of cytokines on human bronchial epithelial cells induced by influenza virus A

Bronchial epithelial cells play an important role in the pathogenesis of some inflammatory diseases of bronchial mucosa. Epithelial-cell-derived cytokines are important in the elucidation of the mechanism by which airway inflammation occurs, especially in respiratory virus infection, because these cells are the primary sites of viral infection. We infected bronchial epithelial cells, NCI-H292, with influenza virus A (H3N2) and examined the concentrations of cytokines, interleukin-6 (IL-6), IL-8 and regulated on activation, normal T cells, expressed and secreted (RANTES), in the culture media of infected cells using the enzyme-linked immunosorbent assay system and gene expression of RANTES on epithelial cells by the reverse-transcriptase-polymerase chain reaction method. We found that significant amounts of IL-6, IL-8 and RANTES were released. RANTES mRNA was also detected in infected bronchial epithelial cells. It is suggested that cytokine production in human bronchial epithelial cells may contribute to the pathogenesis of airway inflammatory disorders.

Induction of apoptotic cell death by direct-current treatment in human leukemic cell lines

Exposure of human leukemic cell lines (HL-60, ML-1, U-937, MOLT-4, EOL-1) to short direct-current (d.c.) treatment induced apoptotic cell death, characterized by cell shrinkage and nuclear and internucleosomal DNA fragmentation. On the other hand, human peripheral blood lymphocytes and polymorphonuclear cells were relatively resistant to d.c. treatment, and did not show any clear nuclear and DNA fragmentation. The effect of d.c. was slightly reduced by calcium depletion, but was not significantly affected by catalase or by superoxide dismutase. The present data suggest that previously reported tumor regression activities of d.c. treatment might be due, at least in part, to its apoptosis-inducing activity.

Expression of IL-6, IL-8, and RANTES on human bronchial epithelial cells, NCI-H292, induced by influenza virus A

Bronchial epithelial cells are primary sites of airway viral infection, and these cells may play an important role in the pathogenesis of respiratory diseases. It has recently been reported that bronchial epithelial cells express RANTES. RANTES attracts monocytes, T cells, eosinophils, and basophils; it can also activate eosinophils. To determine whether viral infection induces RANTES expression on bronchial epithelial cells, we infected a bronchial epithelial cell line, NCI-H292, with influenza virus A (H3N2). We then examined the concentration of RANTES in the culture medium of infected cells by ELISA and assessed expression of the gene for RANTES by the reverse-transcriptase polymerase chain reaction. We also investigated the concentrations of IL-6, IL-8, and granulocyte-macrophage colony-stimulating factor in the medium of infected cells, because some virus infections have been reported to induce expression of these cytokines on bronchial epithelial cells, but there are few data concerning influenza virus infection. Small amounts of IL-6 and IL-8 were detected in the medium of uninfected cells. RANTES was not detected in the medium of uninfected cells. After influenza virus infection, significant amounts of IL-6, IL-8, and RANTES were released into the culture medium of infected cells, and RANTES messenger RNA was detected from infected cells. Granulocyte-macrophage colony-stimulating factor was not detected in the medium of uninfected and infected cells. These results suggest that influenza virus infection may stimulate production of IL-6, IL-8, and RANTES from human bronchial epithelial cells and that these cytokines may contribute to the pathogenesis of airway inflammatory diseases caused by influenza virus infection.

[Anti-allergic effects of beta-adrenoceptor agonists in the clinical pharmacological studies]

Beta-adrenoceptor agonists have several pharmacological actions in the lung which affect airway function. They have a direct relaxant effect on human bronchial smooth muscle and several additional properties, including attenuation of mast cell mediater release, reduction in airway microvascular leakage, and inhibition of cholinergic neurotransmission within the airway, in vitro. However, direct evidence in vivo for any anti-inflammatory effects of beta-adrenocepter agonists is limited. We reported that beta-agonists (procaterol, salmeterol) inhibited significantly I. A. R. and L. A. R. Salmeterol also reduced urinary secretion of LTE4. It is suggested that beta-agonists have some of anti-allergic effects in the clinical pharmacological study. From recent clinical studies, it is recommended on demand use more than regular use of inhaled beta-agonists.

[A case of food-dependent exercise-induced anaphylaxis induced by shrimp]

The clinical study and in vitro study used with leukocytes were made of a case of food-dependent exercise-induced anaphylaxis induced by shrimp. A 26-year-old man experienced anaphylactic reaction of nasal obstruction, face edema and dyspnea while running 90 minutes after eating shrimp. He experienced similar episodes two years ago in his past history. IgE-RAST was positive for shrimp. Anaphylactic reaction and elevation of plasma histamine levels were verified by exercise challenge test after eating 100 g shrimp. At the same time, we verified the dedine of plasma cAMP levels after eating shrimp. In leukocyte stimulating test used with shrimp antigen, histamine level elevations, which were lower compared with calcium ionophore A23187 (Ca I 10(-6) M) stimulation, were recognized in dose dependent manner in this patient. But in normal subject, histamine level elevations were not recognized. We diagnosed him food-dependent exercise-induced anaphylaxis. It was suggested that there was relation between histamine release and decline of cAMP levels of plasma after eating shrimp in this case.

[RANTES expression on human bronchial epithelial cells]

Viral infection induces airway inflammation. It is possible that bronchial epithelium derived chemokine contributes to the migration and accumulation of inflammatory cells in the airway viral infection. We infected bronchial epithelial cells with influenza virus and analysed mRNA expression and production of RANTES. The expression of mRNA and the production of RANTES were detected in infected cells using RT-PCR method and ELISA.

[Effect of dexamethasone on intercellular adhesion molecule-1 expression on cultured bronchial epithelial cells stimulated by inflammatory cytokines]

Bronchial asthma is characterized as a chronic inflammation of the airway that causes an infiltration of lymphocytes and eosinophils. Cell to cell interaction or cell to tissue interaction is essential for infiltration of eosinophils to underlying tissues. These phenomena are closely related to the expression of intercellular adhesion molecule-1 (ICAM-1). Inhalation of steroids, such as beclomethasone dipropionate, is commonly used to cure airway inflammation. In this study, we investigated the effect of cytokines on ICAM-1 expression on human bronchial epithelial cell lines, NCI-H292. Moreover, the effect of dexamethasone on ICAM-1 expression stimulated by IL-1 beta, TNF-alpha and IFN-gamma was observed. Treatment with IL-1 beta, TNF-alpha and IFN-gamma dose-dependently increased ICAM-1 expression on NCI-H292 cells. Inhibitory effects were exerted by dexamethasone on ICAM-1 expression in cells stimulated by IL-1 beta and IFN-gamma in a dose-dependent manner, but not in cells stimulated by TNF-alpha. These results suggest that the inhibition of ICAM-1 expression could be related to the pharmacological action of steroid drugs.

[Cyclosporin A inhibits interleukin 5 (IL-5) production from human peripheral lymphocytes]

Inflammation of mucosa and epithelial damage the of bronchi are characteristic pathological features of asthma. Infiltration of T lymphocytes and eosinophils followed by their activation and release of cytokines seems to be a contributing process. We studied the interaction of interleukin 2 (IL-2) and interleukin 5 (IL-5), cytokines which act on eosinophils, using human peripheral lymphocytes. We found that cyclosporin A (CyA) inhibited the IL-5 production from human peripheral lymphocytes induced by IL-2 stimulation. Human peripheral lymphocytes were isolated from healthy volunteers and bronchial asthma patients with mild eosinophilia. Lymphocyte cultures stimulated with IL-2 were cultured at 37 degrees C in a humidified atmosphere of 5% CO2 in air. After 72 hours' incubation, the proliferative response of the lymphocytes was examined by [3H]thymidine uptake, and at the same time IL-5 in the supernatant of the culture medium was assayed by ELISA. The lymphocytes proliferated on IL-2 stimulation in all cases; IL-5 was detected in 3 out of 9 healthy volunteer cases and 7 out of 11 asthma patient cases. CyA added at the beginning of incubation inhibited both of these responses in a dose-dependent manner.

[The mechanism of airway hyperresponsiveness following immediate bronchial response in ovalbumin (OA)-sensitized guinea pigs]

We have previously demonstrated that airway responsiveness was enhanced following a late bronchial response (LBR) after an allergen challenge in ovalbumin (OA)-sensitized guinea pigs. The purpose of the present studies was to evaluate whether airway responsiveness to methacholine increased after an immediate bronchial response (IBR) and the possible involvement of the beta-adrenoceptor dysfunction in OA-sensitized guinea pigs. Guinea pigs were actively sensitized by aerosolized OA. Following OA exposure, IBR appeared. After IBR when specific airway resistance returned to the base line value, airway responsiveness to methacholine increased significantly. Before OA exposure, propranolol induced bronchoconstriction (PIB) was not provoked, however, after IBR, PIB was provoked and the guinea pigs died because of severe bronchoconstriction. These results suggest that airway responsiveness to methacholine increases significantly after IBR. Furthermore, the dysfunction of the beta-adrenoceptor may be a mechanism of this hyperresponsiveness in OA-sensitized guinea pigs.

[The changes in plasma histamine levels after a sulpyrin inhalation test in asthmatic patients]

A sulpyrin inhalation test was given to 13 patients with aspirin-induced asthma (AIA) and 8 patients with non-aspirin-induced asthma (non-AIA) to observe the changes in plasma histamine levels before and after challenges. The respiratory function (FEV1.0) was measured before and after sulpyrin inhalation. A decrease of more than 20% the initial value (basal value) was defined as a positive response. Plasma histamine was determined by high-performance liquid chromatography (HPLC). In 11 patients with AIA, a positive response was observed (SIT positive), with a fall of FEV1.0 to 63.70 +/- 4.87% of the basal value. In 2 patients with AIA and 8 patients with non-AIA, no positive response was observed (SIT negative). In patients with SIT positive, plasma histamine levels increased significantly from 0.61 +/- 0.06 ng/ml before challenges to 1.34 +/- 0.22 ng/ml after challenges (p less than 0.01). No significant changes of plasma histamine occurred in the SIT negative patients. These results suggest that mast cells play some role in the mechanism of the development of aspirin-induced asthma.

[Study of development of autoantibody to beta-adrenergic receptors in asthmatics]

An (125I) iodohydroxybenzyl pindolol (125IHYP) binding inhibition assay was performed. Various dilutions (1:5-1:500) of sera from asthmatics and controls were incubated with canine lung membranes for 60 minutes at 30 degrees C. 125IHYP was added to the membranes for 30 minutes at room temperature in the presence and absence of 10 microM 1-propranolol, and the samples were washed through a Gelman (Type A-E) glass fiber filter using a washing buffer. Radio activity was measured with Aloka gamma counter. In the presence of various serum dilutions from asthmatics, 125IHYP specific bindings of 0.16 fmol to 4.38 fmol were measured. 125IHYP binding was inhibited in a dose-related and nonspecific manner. Serum, albumin, L-histidine and L-cysteine also inhibited 125IHYP specific binding to beta-receptors. Percentages of inhibition of serum from asthmatics on 125IHYP specific finding to beta-receptors were -17.6% to +9.3%, which were compared with identical dilutions of control serum. There was no significant difference in 125IHYP binding inhibition assay between asthmatics and controls. From these results, development of autoantibody to beta-adrenergic receptors could not be detected in this study.

Diverse organization of immunoglobulin VH gene loci in a primitive vertebrate

The immunoglobulin (Ig) heavy chain variable (VH) gene family of Heterodontus francisci (horned shark), a phylogenetically distant vertebrate, is unique in that VH, diversity (DH), joining (JH) and constant region (CH) gene segments are linked closely, in multiple individual clusters. The V regions of 12 genomic (liver and gonad) DNA clones have been sequenced completely and three organization patterns are evident: (i) VH-D1-D2-JH-CH with unique 12/22 and 12/12 spacers in the respective D recombination signal sequences (RSSs); VH and JH segments have 23 nucleotide (nt) spacers, (ii) VHDH-JH-CH, an unusual germline configuration with joined VH and DH segments and (iii) VHDHJH-CH, with all segmental elements being joined. The latter two configurations do not appear to be pseudogenes. Another VH-D1-D2-JH-CH gene possesses a D1 segment that is flanked by RSSs with 12 nt spacers and a D2 segment with 22/12 spacers. Based on the comparison of spleen, VH+ cDNA sequences to a germline consensus, it is evident that both DH segments as well as junctional and N-type diversity account for Ig variability. In this early vertebrate, the Ig genes share unique properties with higher vertebrate T-cell receptor as well as with Ig and may reflect the structure of a common ancestral antigen binding receptor gene.

Complete structure and organization of immunoglobulin heavy chain constant region genes in a phylogenetically primitive vertebrate

Immunoglobulin (Ig) gene organization in Heterodontus francisci (horned shark), a phylogenetically primitive vertebrate, is unique. Homologous Ig heavy chain variable (VH) and constant region (CH) specific probes were used to screen a spleen cDNA library constructed in lambda gt11. Both secretory (SEC) and transmembrane (TM) cDNA clones were recovered; the latter were identified by a negative selection strategy. The complete sequence of the CH portion of a Heterodontus genomic DNA-lambda clone also was determined. The sequences of the individual CH genes differ from each other in all exons. When compared to mammalian prototypes, similarities in exon and intron organization as well as conservation of sequences involved with differential splicing of SEC and TM mRNA indicate that Heterodontus heavy chain genes are of the mu type, although intron lengths are uniformly longer in Heterodontus. Heterodontus genes are not associated, however, with the family of DNA sequences that have been implicated in heavy chain class switching in mammals. Spleen cDNA library screening and RNA blot analyses indicate that mRNAs encoding TM Ig are exceedingly rare. The relationship between this quantitative difference and the distribution of polyadenylation signal sequences suggests that regulation of Ig gene expression in Heterodontus may be highly dependent on position effects.

Extensive families of constant region genes in a phylogenetically primitive vertebrate indicate an additional level of immunoglobulin complexity

A homologous probe for the constant region of the Heterodontus francisci (horned shark) immunoglobulin heavy chain was used to screen a genomic DNA library constructed in bacteriophage lambda, and a large number of independent clones were recovered. Their hybridization patterns with segment-specific probes are consistent with the close linkage of heavy-chain constant (CH), joining (JH), and variable (VH) gene segments. Differences in the nucleotide sequences of the first CH exon of five genes primarily are localized to 5' positions; extended regions of sequence identity are noted at 3' positions. The predicted amino acid sequences of each gene are different and are related distantly to the corresponding regions of higher vertebrate immunoglobulins. Gene-specific oligodeoxynucleotide probes were used to establish that at least three of the five genes are transcriptionally active. Quantitative gene titration data are consistent with the large numbers of genes suggested by the library screening analyses. In this representative early vertebrate, it appears that (VH-diversity-JH) segments are associated with individual constant region genes that can differ at the predicted protein level.