Immunologic Effector Mechanisms in Animal Models of Occupational Asthma

Abstract

Occupational asthma is a form of immunotoxicity resulting from an exaggerated immune response to substances encountered in the workplace. Symptoms include reversible airway obstruction, airway hyperresponsiveness, airway remodeling, mucus production and cellular infiltration into the lung, particularly eosinophilia. The asthmatic response is divided into the induction phase, occurring after initial exposure to allergen, followed by the effector phase where a subsequent exposure to the allergen results in the respiratory symptoms. Animal models have been used to investigate the asthmatic response and this review will focus on mechanistic studies of the effector phase. Variables that may impact the effector phase include strain and species of animal, dose of allergen, route of exposure, and developmental stage of the animal. Both trimellitic anhydride (TMA) and ovalbumin are known causes of occupational asthma. Ovalbumin is also a reference protein allergen in immunology, and TMA is used as a prototype of a low molecular weight respiratory allergen. Differences in effector mechanisms for TMA and ovalbumin have been noted in different animal models. Studies in the guinea pig provide the most direct comparisons of effector mechanisms of TMA and ovalbumin, with differences in the role of the complement system and arachidonate metabolites being noted. Besides the guinea pig, the Brown Norway rat, and various mouse strains provide useful asthma models for TMA and ovalbumin. However, studies of effector mechanisms are somewhat lacking in either of these species using TMA as the allergen. Continued studies are indicated to determine if unique effector mechanisms can be identified for the many different causes of occupational asthma.

Puerarin Attenuates Ovalbumin‐Induced Lung Inflammation and Hemostatic Unbalance in Rat Asthma Model

“…Additionally, the total cell number in BALF of asthmatic rats was significantly higher than other groups ( P < 0.01, Figure 1), and rats treated with drugs showed substantial decrease compared with asthmatic rats ( P < 0.01, Figure 1). One of the basic features of allergic asthma has been shown to be the eosinophilic airway inflammation [1, 31]. Therefore, eosinophilic percentage was examined as a major biomarker for allergic asthma; our results indicated that drugs used in this study could effectively reduce the eosinophil numbers in BALF ( P < 0.01, Figure 1).…”

“…Asthma is a chronic inflammatory disease of the airways characterised by eosinophilic infiltration, airway hyperresponsiveness, and structural remodeling [1–3], along with hemostatic unbalance [4, 5]. Asthma morbidity and mortality have been increasing in recent decades [6–8].…”

Inhibitory Effect of Sihuangxiechai Decoction on Ovalbumin‐Induced Airway Inflammation in Guinea Pigs

“…This result suggested that sihuangxiechai decoction has an effect on the OVA-induced asthma. In addition, Regal [35] and Holgate et al [36] concluded that Eos airway inflammation has been shown to be one of the basic features of allergic asthma. In our study, the percentage of Eos infiltrating in TCM group was significantly decreased in BALF and blood after OVA challenge (Figure 2) compared with the asthma group.…”

Assessment of Airway Sensitization Potential of Inhaled Trimellitic Anhydride by Monitoring the Elicitation Phase in a Mouse Model

“…According to Regal (2004), bronchoconstriction in response to antigen is the result of smooth muscle contraction and airway narrowing, and possible factors of airway narrowing are edema, increased vascular permeability and mucus production. It is still necessary for us to clarify via what mechanism(s) Penh was augmented after TMA inhalation challenge in our model.…”