Allergen-triggered airway hyperresponsiveness and lung pathology in mice sensitized with the biopesticide Metarhizium anisopliae

• Published in: Toxicology (Amsterdam) Vol. 143; no. 2; pp. 141 - 154
• Main Authors: Ward, Marsha D.W, Madison, Sharon L, Sailstad, Denise M, Gavett, Stephen H, Selgrade, MaryJane K
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 21.02.2000; Amsterdam Elsevier Science
• Subjects: Allergens - toxicity; Allergic diseases; Animals; Antigen; Biological and medical sciences; Bronchial Hyperreactivity - immunology; Bronchial Hyperreactivity - pathology; Bronchoalveolar Lavage Fluid - cytology; Bronchoalveolar Lavage Fluid - immunology; Cell Count - drug effects; Enzyme-Linked Immunosorbent Assay; Eosinophilia - chemically induced; Female; Fugus; Immunoglobulin E - immunology; Immunopathology; Insect Control; Interferon-gamma - biosynthesis; Interleukin-4 - metabolism; Interleukin-5 - biosynthesis; Lung - pathology; Lymphocyte Count - drug effects; Medical sciences; Metarhizium anisopliae; Mice; Mice, Inbred BALB C; Mitosporic Fungi - immunology; Mouse; Respiratory and ent allergic diseases; PMN, polymorphonuclear leukocytes; SEM, standard error of the mean; Fugus; HBSS, Hank’s balanced salt solution; BALF, bronchoalveolar lavage fluid; IT, intratracheal; DPIT, days post MACA IT challenge; MACA, Metarhizium anisopliae crude antigen; Antigen; IP, intraperitoneal; Mouse; BAL, bronchoalveolar lavage; Mch, methacholine; Immunopathology; Allergy; Respiratory disease; Toxicity; Lung; Rodentia; Allergenicity; Fungi; Vertebrata; Mammalia; Histopathology; Immunogenicity; Metarhizium anisopliae; Animal; Sensitization; Fungi Imperfecti; Biopesticide; Thallophyta
• ISSN: 0300-483X; 1879-3185
• DOI: 10.1016/S0300-483X(99)00166-3

Metarhizium anisopliae is an entomopathogenic fungus recently licensed for indoor control of cockroaches, a major source of allergens. While M. anisopliae has been shown to be non-infectious and non-toxic to mammals there has been only limited research on potential allergenicity. Using a mouse model, we previously demonstrated allergic immune and inflammatory responses to this agent. The present study was designed to determine whether these responses were associated with changes in pulmonary responses, lung pathology, and the cytokine profile in bronchoalveolar lavage fluid (BALF). Soluble factors from fungal components were combined in equal protein amounts to form M. anisopliae crude antigen (MACA). BALB/C mice were intratracheally (IT) challenged with 10 μg MACA 14 days post intraperitoneal sensitization with 25 μg fungal antigen in aluminum hydroxide adjuvant. Physiological and cellular changes were examined. The mice were tested for airway hyperresponsiveness before (No Chal) and after (1, 3, and 8 days post challenge (DPIT)) MACA IT challenge. Subsequently, serum, BALF and the lungs were harvested. All treatment groups concurrently demonstrated significant non-specific pulmonary inflammation (neutrophil influx) and increased pulmonary sensitivity to methacholine (Mch) at 1 DPIT MACA challenge. Where as both adjuvant treated and naı̈ve mice airway responses had returned to near normal levels by 3 DPIT, mice which were previously sensitized with MACA were still hyperresponsive to Mch challenge at 3 and 8 DPIT. This hyperresponsiveness correlates with eosinophil and lymphocyte influx, which is maximal at 3 DPIT and still elevated at 8 DPIT. Interleukin (IL) 5 was elevated for all treatment groups at 1 DPIT but only the MACA sensitized mice maintained elevated levels for both 3 and 8 DPIT. Furthermore, MACA sensitized mice had a more extensive inflammatory histopathology at all examined time points with peribronchial and perivascular infiltrates, like those associated with allergic responsiveness, peaking at 3 DPIT. These pulmonary pathologic changes appeared to be consistent with elevated levels of serum and BALF total IgE, BALF IL-4, eosinophils, and lymphocytes following MACA IT challenge in MACA sensitized mice. There were no significant differences among the three treatment groups with regard to BALF interferon (IFN) γ. The cytokines profiled indicate a Th2-type response, which is reflected in the cellular influx and total IgE induction. These data further indicate that immune inflammatory responses, observed in mice following MACA sensitization and challenge, are associated with physiologic changes and histopathology characteristic of allergic disease.