Susceptibility Analysis in Several Mouse Strains Reveals Robust T-Cell Responses After Mycoplasma pneumoniae Infection in DBA/2 Mice

Abstract

Mycoplasma pneumoniae (Mp) is a highly contagious respiratory pathogen responsible for human community-acquired pneumonia. The number of antibiotic-resistant Mp strains is increasing; therefore, to develop novel therapeutics, it is crucial to precisely understand the pathogenesis of mycoplasma pneumonia. Herein, we examined the susceptibility and response to Mp among eight inbred mouse strains. Following infection, the bacterial load in the bronchoalveolar lavage fluid (BALF) from DBA/2 mice was higher than that in the other tested strains such as BALB/c mice, which are frequently used in Mp research. In contrast, the numbers of CD45+ immune cells and neutrophils in BALF were comparable between BALB/c and DBA/2 mice, with lower numbers observed in C57BL/6J and CBA/N mice than in BALB/c mice. Among the tested strains, the BALF level of interleukin 12 subunit p40 was highest in DBA/2 mice; however, significant differences in other cytokines levels were not observed between BALB/c and DBA/2 mice. After Mp infection, Mp-specific Th1 and Th17 responses were significantly enhanced in DBA/2 mice when compared with BALB/c mice. Furthermore, prior infection with Mp increased the number of neutrophils in BALF after the reinfection of DBA/2 mice through an Mp-specific CD4+ T cell-dependent mechanism. Thus, DBA/2 may be an appropriate strain for evaluating Mp infection. Moreover, a comparison of responses revealed by various inbred mouse strains could be useful for elucidating the pathogenesis of Mycoplasma pneumonia.

Bacterial expression of a designed single‐chain IL ‐10 prevents severe lung inflammation

“…MPN induces an inflammatory response in the lungs of mice (Waites & Talkington, 2004 ; Tamiya et al , 2021 ). To solve this issue, we engineered an attenuated strain, referred to here as chassis CV8 (patent application EP 20382207.7).…”

Neutrophil-Mediated Lung Injury Both via TLR2-Dependent Production of IL-1α and IL-12 p40, and TLR2-Independent CARDS Toxin after Mycoplasma pneumoniae Infection in Mice

“…The FH strain of Mp was purchased from the American Type Culture Collection (Manassas, VA, USA). Mp was cultured as described previously ( 48 , 49 ). The mice were challenged intranasally with 6 × 10 7 CFU Mp in 40 μl of PBS under anesthesia.…”

“…After Mp challenge, the DNA copies of Mp, immune cells, and the level of cytokines in BALF obtained by lavaging the lung with 1.2 ml PBS were analyzed. The DNA copies of Mp in BALF were determined by real-time PCR analysis as described previously ( 48 , 49 ).…”

“…BALF was centrifuged at 600 × g for 5 min, and the resulting cell pellets were used to identify the various immune cell subsets in BALF using flow cytometry (NovoCyte Flow Cytometer, ACEA Bioscience, San Diego, CA, USA) as described previously ( 48 , 49 ). We defined the neutrophils as CD45 + Ly6G + CD11b + Siglec-F – and alveolar macrophages as CD45 + Ly6G – CD11c + Siglec-F + .…”