The effects of inhalation of diesel exhaust on murine mycobacterial infection.
The authors investigated the effects of inhalation of diesel exhaust (DE) on murine mycobacterial infection in vivo. Eight-week-old female BALB/c mice were exposed to DE (3 mg/m3 of diesel exhaust particles [DEPs]) for 1 month, 2 months, or 6 months (for 7 hours a day, 5 days a week). Control mice were housed in a clean room for the same periods. On the day following the last DE exposure, control mice and DE-exposed mice were aerially infected with Mycobacterium tuberculosis (1 x 10(6) colony-forming units (CFU), Kurono strain). At 7 weeks after mycobacterial infection, the authors examined the lung tissues for histopathological changes and performed reverse transcriptase-polymerase chain reaction (RT-PCR) to measure the messenger RNA (mRNA) expression of several proinflammatory cytokines and inducible nitric oxide synthase (iNOS). Then, the homogenates of lungs and spleens were cultured on 1% (v/v) Ogawa's egg slant medium, and after a 4-week incubation period at 37 degrees C, colonies on the medium were counted. After 1 month of DE exposure, the mycobacterial infection had slightly ameliorated. After 2 months of DE exposure, the expression levels of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-12p40, interferon (IFN)-gamma, and iNOS mRNAs were slightly increased. However, after 6 months of DE exposure, the expression levels of IL-1beta , IL-12p40, IFN-gamma, and iNOS mRNAs were decreased, and the infection as measured by increased lung burden (CFU) actually increased. These results indicate that long-term DE exposure may increase pulmonary mycobacterial burden.
Hiramatsu
Kumiko
K
Fourth Department of Internal Medicine, Nippon Medical School, Tokyo, Japan.
Saito
Yoshinobu
Y
Sakakibara
Keitaro
K
Azuma
Arata
A
Takizawa
Hajime
H
Sugawara
Isamu
I
D000280:Administration, Inhalation; D000818:Animals; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D004198:Disease Susceptibility / Q000378:metabolism; D005260:Female; D008168:Lung / Q000187:drug effects* / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D009169:Mycobacterium tuberculosis / Q000472:pathogenicity; D019001:Nitric Oxide Synthase / Q000096:biosynthesis / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013154:Spleen / Q000382:microbiology; D013997:Time Factors; D014397:Tuberculosis, Pulmonary / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D001335:Vehicle Emissions / Q000633:toxicity*
D016207:Cytokines; D012333:RNA, Messenger; D001335:Vehicle Emissions; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse