Mycobacterium terrae isolated from indoor air of a moisture-damaged building induces sustained biphasic inflammatory response in mouse lungs.

Abstract

Occupants in moisture-damaged buildings suffer frequently from respiratory symptoms. This may be partly due to the presence of abnormal microbial growth or the altered microbial flora in the damaged buildings. However, the specific effects of the microbes on respiratory health and the way they provoke clinical manifestations are poorly understood. In the present study, we exposed mice via intratracheal instillation to a single dose of Mycobacterium terrae isolated from the indoor air of a moisture-damaged building (1 X 10(7), 5 X 10(7), or 1 X 10(8) microbes). Inflammation and toxicity in lungs were evaluated 2 hr later. The time course of the effects was assessed with the dose of 1 X 10(8) bacterial cells for up to 28 days. M. terrae caused a sustained biphasic inflammation in mouse lungs. The characteristic features for the first phase, which lasted from 6 hr to 3 days, were elevated proinflammatory cytokine [i.e., tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6)] levels in the bronchoalveolar lavage fluid (BALF). TNF-alpha was produced in the lungs more intensively than was IL-6. Neutrophils were the most abundant cells in the airways during the first phase, although their numbers in BALF remained elevated up to 21 days. The characteristics of the second phase, which lasted from 7 to 28 days, were elevated TNF-alpha levels in BALF, expression of inducible nitric oxide synthase in BAL cells, and recruitment of mononuclear cells such as lymphocytes and macrophages into the airways. Moreover, total protein, albumin, and lactate dehydrogenase concentrations were elevated in both phases in BALF. The bacteria were detected in lungs up to 28 days. In summary, these observations indicate that M. terrae is capable of provoking a sustained, biphasic inflammation in mouse lungs and can cause a moderate degree of cytotoxicity. Thus, M. terrae can be considered a species with potential to adversely affect the health of the occupants of moisture-damaged buildings.

Assessment of DNA damage and repair in Mycobacterium terrae after exposure to UV irradiation

“…Mycobacterium terrae is a slow growing mycobacteria usually considered to be nonpathogenic to humans, however a few cases of lung infection have been observed (Zenone et al. 1999; Jussila et al. 2002).…”

Mycobacteria and Fungi in Moisture-Damaged Building Materials

“…Such strains have induced inflammatory responses, the production of NO and the cytokines interleukin-6 and tumor necrosis factor alpha, in both human and murine cells (6,7). M. terrae has also caused a sustained inflammation in mouse lungs (11). Exposure to mycobacteria may be associated with symptoms with an inflammatory pathway without infection.…”

High Indoor Microbial Levels Are Associated with Reduced Th1 Cytokine Secretion Capacity in Infancy

“…However, it should be noted that indoor dust includes several nonpathogenic mycobacterial species (e.g. the very common Mycobacterium terrae [17]) that seem to be capable of immunomodulation in animal and cell line studies [29,30]. In addition, different species of Mycobacterium seem to induce cytokine secretion, e.g.…”