Attenuation of house dust mite Dermatophagoides farinae-induced airway allergic responses in mice by dehydroepiandrosterone is correlated with down-regulation of TH2 response

BACKGROUND

Dehydroepiandrosterone (DHEA), an abundant androgen in circulation, has important immunomodulating effects on T-cell differentiation; however, it is not known whether this hormone influences allergic responses.

OBJECTIVE

We have established a murine model of airway inflammation induced by house dust mite Dermatophagoides farinae (Der f). Der f challenge of sensitized mice would elicit a pulmonary eosinophilic inflammation. In the present study, we employed this model system to explore the effect of DHEA on allergic responses.

METHODS

Female BALB/c mice were fed with a standard diet incorporated with 1.5% (w/w) of DHEA for 1 week before sensitization and every other day for an additional 2 weeks after sensitization. After intratracheal inoculation of allergen, the Der f-induced airway inflammation, immunoglobulin (Ig)E antibody production, and cytokine expression were compared between control and DHEA-fed mice.

RESULTS

In control mice the Der f-induced eosinophilia in bronchoalveolar lavage (BAL) fluids was accompanied by an increase in production of interleukin (IL)-4, IL-5, and interferon IFN-gamma systemically and locally. DHEA supplementation did not affect the body weight of mice. However, in mice that were receiving DHEA, the numbers of eosinophils and lymphocytes in BAL fluids significantly decreased at days 2 and 6 after challenge as compared with control mice. Concomitantly, total IgE antibody concentrations as well as IL-4, IL-5, and IFN-gamma levels in BAL fluids or serum also significantly reduced. Immunocytochemical staining of BAL cells revealed that there were fewer IL-4-, IL-5-, IL-10-, but not IFN-gamma-positive stained cells in DHEA-fed mice than in mice who consumed unsupplemented diet. Reverse transcription-polymerase chain reaction analysis demonstrated DHEA decreased the expression of IL-5 and IL-10 transcripts in BAL cells.

CONCLUSIONS

Our results showed that administration of DHEA during allergic sensitization could attenuate the subsequent allergic responses elicited by challenge, and that the suppressive effect of DHEA was associated with a down-regulation of TH2 response.

Exogenous dehydroepiandrosterone modified the expression of T helper-related cytokines in NZB/NZW F1 mice

The onset of lupus-like disease in NZB/NZW F1 mice was correlated with the expression of IL-10 at 4 m of age, and with a sequential enhanced expression of IFN-gamma and IL-6 between 6 to 8 m of age. The expression of IFN-gamma and IL-6 was associated with exacerbation of disease symptom, production of anti-DNA antibody, and increase in total serum IgG1. Exogenous dehydroepiandrosterone (DHEA) given in animal diet significantly prolonged survival, and delayed formation of autoantibody of NZB/NZW F1 mice as compared to mice fed on control diet. The effect of DHEA paralleled a delay in the expression of IL-10 and IL-6 and an earlier detection of IL-12 transcripts. Moreover, DHEA-fed mice had higher serum IgG2a level than control diet-fed mice. Collectively, DHEA may modify the activation of distinct subset of T helper cells in NZB/NZW F1 mice at different phases of disease progression.

Women's attitudes to and awareness of smear testing and cervical cancer

A cross sectional survey consisting of a questionnaire of 650 randomly selected women aged 15 to 78 years was performed to gain an insight into women's attitudes to and awareness of smear testing and cervical cancer. Their general health and screening history were noted along with their knowledge of the smear test and cervical cancer. Of the respondents, 80.5 per cent had had at least one smear test and 71.5 per cent of these women have regular smears. The majority of the women (66.9 per cent) thought the test 'no problem' and those who found the test 'embarrassing, painful or troublesome' were of a younger age group. Overall, 76.2 per cent perceived the disease to be a common one. 32.6 per cent of the respondents thought the age group 40s to 50s to be most affected by cervical cancer. On the whole, women appeared to be well informed of the link between the number of sexual partners and cervical cancer as well as recognising smoking to be a contributing factor. A substantial proportion (91.7 per cent) of women were of the attitude that cancer can be treated if detected early enough. The perceived barrier such as embarrassment and discomfort played a part in women's decision in returning for a regular smear. By influencing the awareness and perceptions through public health education as well as creating an appropriate environment for the test, this can indeed help to reduce personal perceived barriers and increase the uptake of smear testing.

Dermatophagoides-farinae-induced pulmonary eosinophilic inflammation in mice

Dermatophagoides farinae (Der f) is one of the most common species of dust mites that induce asthma and allergic rhinitis. We have reported that Der f challenge on sensitized mice elicited a distinct type of hypersensitivity, called early-type hypersensitivity (ETH), in subcutaneous tissues and in airways. The airway ETH was accompanied by a series of inflammatory and immunological events including cytokine production, adhesion molecule expression, inflammatory cell infiltration, eosinophilia, and airway hyperreactivity. In the present study, we further defined the course of the Der-f-induced eosinophilia and examined the local cytokine gene expression and the roles of cytokines, mast-cell-derived vasoactive amines, and corticosteroids in the development of pulmonary eosinophilia. BALB/c mice were sensitized with crude extract of Der f in complete Freund's adjuvant and were intranasally challenged with Der f on day 14 after sensitization. The number of blood eosinophils, total and differential leukocyte counts in bronchoalveolar lavage (BAL) fluids, and the expression of cytokine genes in BAL cells were assessed at various time points after challenge for up to 12 days. The total number of leukocytes in the BAL fluids was increased 6 h after challenge (AC) and peaked at 72 h. The early cellular response in the BAL fluids was dominated by neutrophils which were subsequently replaced by a marked infiltration of eosinophils. The number of eosinophils in BAL fluids increased at 24 h and peaked at 72 h, making up 43% of all cells recovered by BAL. BAL eosinophils declined gradually to normal background levels around day 12. Concurrently, there was a significant reduction in the number of eosinophils in blood 24 h AC. The number of blood eosinophils increased thereafter, reached a peak at 72 h, and remained above baseline level for up to 10 days. Saline challenge did not induce eosinophilia in BAL fluids and blood of sensitized mice. Histopathological examination revealed a mixed granulocytic, monocytic pulmonary inflammation with a large number of eosinophils accumulating within the submucosa of the airways and blood vessels of sensitized mice after challenge. Der f challenge induced a sequential expression pattern of eight cytokine genes in BAL cells. The mRNA of interleukin (IL)-1 beta and tumor necrosis factor (TNF)-alpha strongly expressed throughout the course of the experiment. The IL-6 mRNA expression peaked at 0.5-72 h, IL-10 at 1-6 and 48-72 h, IL-4 at 6-72 h, IL-2 at 6-96 h, IL-5 at 24-72 h, and interferon-gamma at 24-96 h. Intraperitoneal injection of sensitized mice with monoclonal antibody (mAb) to murine IL-5 (TRFK5, 300 micrograms/mouse) 1 h before challenge caused 62% suppression of eosinophils in the BAL fluids. The concomitant accumulation of neutrophils and mononuclear cells, however, was not affected by this treatment. On the other hand, intranasal administration of mAb to murine TNF-alpha (MP6-XT3, 20 micrograms/ mouse), but not IL-5, 1 h before challenge and 24 h AC significantly reduced the numbers of eosinophils, neutrophils, and lymphocytes in the BAL fluids. The intraperitoneal injection of dexamethasone (50 mg/kg) for a total of four times resulted in total inhibition of the Der-f-induced cellular responses, whereas vasoactive amine antagonists (diphenhydramine, ketanserin and cyprohepatidine) did not show any effect.

Early-type hypersensitivity-associated airway inflammation and eosinophilia induced by Dermatophagoides farinae in sensitized mice

In a murine ear-swelling model, we demonstrated a unique hypersensitivity response and defined it as early-type hypersensitivity (ETH). ETH was characterized by increased vasopermeability and edematous change that occurred within 1 h at the site of Ag challenge. In this study, intranasal challenge with Dermatophagoides farinae (Df) on Df-sensitized BALB/c mice induced an ETH response in the lungs. The lung ETH was manifested by an increase in wet lung weight, production of TNF-alpha in bronchoalveolar lavage fluids, and hyperemia and edematous change around vessels of small airways 1 h after Ag provocation. The challenged animals subsequently developed airway inflammation, beginning with a neutrophilic infiltrate which was followed by lymphocytes and eosinophils. The Df-induced eosinophilia was Ag-specific and maximal at 48 h after challenge. At this time, the trachea from sensitized mice also exhibited hyperreactivity to carbachol. Pretreatment with anti-CD4+ mAb significantly decreased the recruitment of eosinophils in bronchoalveolar lavage fluids. An enhanced expression of pulmonary endothelial vascular cell adhesion molecule-1 was noted as early as 6 h after challenge. Anti-Df Abs of IgG class, but not IgE class, were detected in Df-immunized mice at the time of challenge. Furthermore, Df challenge induced a stronger eosinophil response in BALB/c mice (H-2d) than in B10.BR (H-2k) mice. B10.BR mice also did not exhibit pulmonary edema or ETH of ear swelling 1 h after challenge. These data suggest that an ETH-associated 1 h pulmonary edematous change was induced by intranasal challenge of Df in Df-sensitized mice, and that the ETH might contribute to the development of subsequent pulmonary inflammation and eosinophilia.

Early-type hypersensitivity-associated airway inflammation and eosinophilia induced by Dermatophagoides farinae in sensitized mice

In a murine ear-swelling model, we demonstrated a unique hypersensitivity response and defined it as early-type hypersensitivity (ETH). ETH was characterized by increased vasopermeability and edematous change that occurred within 1 h at the site of Ag challenge. In this study, intranasal challenge with Dermatophagoides farinae (Df) on Df-sensitized BALB/c mice induced an ETH response in the lungs. The lung ETH was manifested by an increase in wet lung weight, production of TNF-alpha in bronchoalveolar lavage fluids, and hyperemia and edematous change around vessels of small airways 1 h after Ag provocation. The challenged animals subsequently developed airway inflammation, beginning with a neutrophilic infiltrate which was followed by lymphocytes and eosinophils. The Df-induced eosinophilia was Ag-specific and maximal at 48 h after challenge. At this time, the trachea from sensitized mice also exhibited hyperreactivity to carbachol. Pretreatment with anti-CD4+ mAb significantly decreased the recruitment of eosinophils in bronchoalveolar lavage fluids. An enhanced expression of pulmonary endothelial vascular cell adhesion molecule-1 was noted as early as 6 h after challenge. Anti-Df Abs of IgG class, but not IgE class, were detected in Df-immunized mice at the time of challenge. Furthermore, Df challenge induced a stronger eosinophil response in BALB/c mice (H-2d) than in B10.BR (H-2k) mice. B10.BR mice also did not exhibit pulmonary edema or ETH of ear swelling 1 h after challenge. These data suggest that an ETH-associated 1 h pulmonary edematous change was induced by intranasal challenge of Df in Df-sensitized mice, and that the ETH might contribute to the development of subsequent pulmonary inflammation and eosinophilia.

Detection of airway CO2 partial pressure to avoid esophageal intubation

During endotracheal intubation, checking the position of endotracheal tube is important in order to avoid accidental esophageal intubation. Exhaled CO2 pressures of 50 emergent intubation attempts were recorded in our pediatric intensive unit to evaluate the efficacy of capnography in the early detection of esophageal intubation. Adjustment of the tube position was performed when indicated. In successful endotracheal intubation, the end-tidal CO2 pressures (PetCO2) ranged from 10 mmHg to 80 mmHg with typical respiratory phasic waveforms. In cases of inadvertent esophageal intubation, the PetCO2 values were less than 5 mmHg and revealed no typical respiratory pattern. It was also observed that PetCO2 decreased during one lung intubation or when the tip of endotracheal tube was pulled above the glottis. Capnographic monitoring end-tidal CO2 pressure continuously may be a reliable, time-saving tool for the detection of inadvertent esophageal intubation and the evaluation of proper positioning of the endotracheal tube.

Distinct regulation of humoral and cellular immunities to hepatitis B surface antigen

The surface envelope protein of hepatitis B virus (HBsAg) stimulates the immune system to produce anti-HBs antibodies and to generate cell-mediated immunity. These two arms of immunity were found to be regulated differently in bm12 (H-2bm12) or CBA and C3H (H-2k) mice. In bm12 mutant (I-A beta mutant of B6 mice) mice, the anti-HBs production, early-type, and immune complex-type hypersensitivity were impaired, but the delayed-type hypersensitivity and the T-cell proliferation in vitro were normal compared to the parental B6 (H-2b) mice. The mutation of the A beta molecule seems to affect the immune responses differentially. On the other hand, C3H or CBA mice produced anti-HBs antibodies after major S protein (pre-S-depleted HBsAg) stimulation, but could not generate the hypersensitivity responses. The pre-S region could circumvent the non-responsiveness of the hypersensitivity response in C3H and CBA mice. These data suggest that the humoral and cellular immunities to the HBsAg particle are regulated distinctly and are affected by either the A beta molecule of the host or the pre-S region of the HBsAg.

Novel studies on a "silent" high affinity mutant hemoglobin (San Diego, beta 109 Val replaced by Met)

A patient with a "silent" mutant hemoglobin characterized by high oxygen affinity and erythrocytosis is described. A novel approach was used to identify the mutant chain. Functionally active alpha and beta chains were prepared from hemolysates of the patient and a normal control. Hybrid tetramers of patient's beta chain were prepared. Functional studies revealed that the patient's beta chains had a higher oxygen affinity (P50, 1.1 torr) than normal beta chains (P50, 1.7 torr) and the hybrid containing the patient's beta chains had a P50 similar to the patient's "stripped" hemolysate. It was assumed therefore that the mutation was in the beta chain; structural studies using cyanogen bromide cleavage revealed that the patient had Hb San Diego, beta 109 Val replaced by Met, and that the patient's cells contained approximately 50 percent mutant hemoglobin.

Ultraviolet light-induced division delayed in synchronized Chinese hamster cells

The age-dependent, ultraviolet light (UVL) (254 nm)-induced division delay of surviving and nonsurviving Chinese hamster cells was studied. The response was examined after UVL exposures adjusted to yield approximately the same survival levels at different stages of the cell cycle, 60% or 30% survival. Cells irradiated in the middle of S suffered the longest division delay, and cells exposed in mitosis or in G(1) had about the same smaller delay in division. Cells irradiated in G(2), however, were not delayed at either survival level. It was further established, after exposures that yielded about 30% survivors at various stages of the cycle, that surviving cells had shorter delays than nonsurvivors. This difference was not observed for cells in G(2) at the time of exposure; i.e., neither surviving nor nonsurviving G(2) cells were delayed in division. The examination of mitotic index vs. time revealed that most cells reach mitosis, but all of the increase in the number of cells in the population can be accounted for by the increase of the viable cell fraction. These observations suggest strongly that nonsurviving cells, although present during most of the experiment, are stopped at mitosis and do not divide. Cells in mitosis at the time of irradiation complete their division, and in the same length of time as unirradiated controls. Division and mitotic delays after UVL are relatively much larger than after X-ray doses that reduce survival to about the same level.

Mitotic delay and chromosomal aberrations induced by X rays in synchronized Chinese hamster cells in vitro

Synchronized Chinese hamster cell populations in vitro were X-irradiated at different stages of the cell cycle and examined at the next metaphase. Mitotic delay varied according to the stage of the cell cycle at the time of irradiation. It was greatest for cells irradiated in middle to late S, moderate for cells irradiated in G2, and least for cells irradiated in G1. It increased approximately linearly with dose (0.7 hr./100 rad for S cells and 0.3 hr./100 rad for G1 cells). Chromosomal aberration rates also depended on the stage of the cell cycle at which the cells were irradiated. Chromatid aberrations were induced mostly during G2 and S (more in early S than late S), while chromosome aberrations were induced mainly in G1. Total breaks after 500 or 750 R showed a minimum frequency in late S and a maximum frequency in G2. This form of response correlates, but only in a general qualitative way, with the dependence of survival on cell cycle stage previously reported. Mitotic delay has a dependence on cell cycle stage quite different from either chromosomal aberrations or survival.