Acellular filtrate of a microbial-based cleaning product potentiates house dust mite allergic lung inflammation

Microbial-based cleaning products (MBCPs) contain bacteria and chemical constituents. They are used in consumer applications such as odor reduction, unclogging drains, and surface cleaning. To determine the capacity of a model MBCP to contribute to acute allergic lung inflammation, a two-week repeated exposure regimen was used. Mice were exposed by endotracheal instillation to saline alone, MBCP alone, house dust mites (HDM) alone, or sequentially (i.e., MBCP followed by HDM, HDM followed by MBCP, or HDM + MBCP followed by HDM). Both whole MBCP and acellular MBCP filtrate were investigated, and showed minimal differences in the endpoints examined. HDM exposure caused pulmonary perivascular inflammation, bronchiolar mucous cell metaplasia, elevated bronchoalveolar lavage fluid (BALF) eosinophils, and HDM-specific IgG1. For MBCP, notable changes were associated with sequential exposures. MBCP/HDM caused elevated T_H2 cytokines in BALF, and elevated neutrophils, eosinophils and IL-5 in peripheral blood. Co-administration of MBCP and HDM followed by HDM resulted in elevated blood and BALF eosinophils and HDM-specific IgE and IgG1. These results demonstrated that acellular MBCP filtrate, and not bacteria within MBCPs, potentiated the acute allergic inflammation to HDM. This methodology could be extended to investigate chronic allergic inflammation and inflammatory potential of other MBCPs and biotechnology products with complex compositions.