Experimental Asthma Developed by Room Air Contamination with Cockroach Allergen

Abstract

To study the asthmatogenic effect of certain airborne elements of the home environment, we studied a group of guinea pigs exposed to aerosolized cockroach allergen (CRa) and side-stream cigarette (S-SC) smoke. Four groups of guinea pigs were exposed to aerosols, either saline or CRa, for 4 weeks, after a sham or S-SC smoke pretreatment. Anaphylactic antibodies were measured by passive cutaneous anaphylaxis (PCA) assay and by skin test. Animals were challenged with aerosol CRa on day 35, and lung function and leukotrienes (LTB₄ and LTC₄/D₄) were measured. Skin tests were positive on days 21 and 29. The antibodies were heat-stable, IgG1a-like antibodies (PCA titers 1:2–18). The CRa challenge caused an immediate reduction in both the maximal expiratory flow rate at 50% of the lung capacity and respiratory compliance. The decreased lung function continued for up to 6 h (p < 0.0001). LTB₄ and LTC₄/D₄ were elevated (p < 0.0001) in the sensitized animals at the corresponding times of reduced lung function. S-SC smoke did not affect the CRa sensitization; instead, a protective effect on the CRa-induced bronchospasms was noted. Thus, the study indicates that a simple airborne CRa exposure without an adjuvant sensitizes guinea pigs, and that the animals respond to antigen challenge with CRa-specific airway obstructions.

Contractile Responses to Allergen and Cholinergic Stimulation in Bronchus and Trachea of Cockroach Allergen-Sensitized Guinea Pigs

“…Unlike our CRa aerosol sensitization a great majority of other animal models were immunized with an allergen given intraperitoneally and often with an adjuvant [9, 10, 11, 14]. In our study the state of immunization of guinea pigs was proven by the presence of anti-CRa IgG1 [16, 17, 18] as well as by the cellularity in BAL fluid (table 1). Yet, our findings, normal contractile response to ACh and leukocytosis in BAL, closely resemble the report by Wills-Karp et al [12], whose guinea pigs were intraperitoneally immunized with OA.…”

“…The aerosol exposure was carried out for a period of 45 min repeated twice a day, 5 days a week, for 4 weeks. After 4 weeks of immunization, development of anaphylactic sensitivity to CRa was confirmed by both allergic skin test and PCA test as described [16, 17, 18]. Five days after the last aerosol exposure, the asthmatic responses in vivo were measured using a double chamber plethysmograph following CRa challenge (1 mg/ml × 10 ml) in conscious state as described [18].…”

“…Previously, our laboratory reported that guinea pigs exposed chronically to airborne CRa developed allergic sensitization and that subsequent CRa challenge induced asthma-like lung function changes [16, 17, 18]. As a part of the study to elucidate the mechanisms of CRa-induced asthma, the authors investigated the contractile responses of airway smooth muscles in vitro to cholinergic stimulants, ACh and electrical field stimulation (EFS), using tracheal (TSM) and bronchial (BSM) smooth muscle rings, isolated from the guinea pigs chronically immunized by aerosolized CRa or from nonimmunized guinea pigs and passively sensitized with sera of CRa-immunized guinea pigs.…”

Aggravation of Allergic Rhinitis by Air Pollution: Demonstration by an Animal Model of Pollenosis

“…In experimental animal models, chronic coexposure to ETS increased levels of allergen-induced airway remodelling and airway responsiveness by up-regulating the expression of chemokines (Min, 2007), suggesting that ETS is a risk factor for asthma. Other studies using animal models have also reported that exposure to ETS aggravates airway allergy (Seymour, 1997(Seymour, , 2003(Seymour, , 2005Rumold, 2001), although there are also controversial reports (Kang, 1996;Boweles, 2005). In contrast, the effect of mainstream or active cigarette smoking (MTS) on asthma is controversial.…”

Exposures from Indoor Spraying of Chlorpyrifos Pose Greater Health Risks to Children than Currently Estimated

“…Additional studies need to consider whether pesticide treatment for insects such as cockroaches could heighten allergenic response because cockroach antigen remains one of the most commonly reported causes of asthma (10,11). In addition, a number of cases have been reported of birth defects in children born to mothers who have previously had healthy babies.…”