AUTHOR=Qin Tian , Yu Ting , Liu Yuqi , Wu Jiguo , Jiang Yunxia , Zhang Guoxia 

TITLE=Roseicella aerolata GB24T from bioaerosol attenuates Streptococcus pneumoniae-introduced inflammation through regulation of gut microbiota and acetic acid

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1225548

DOI=10.3389/fmicb.2023.1225548

ISSN=1664-302X

ABSTRACT=<p><italic>Streptococcus pneumoniae</italic> (<italic>Spn</italic>) is the most common respiratory pathogen causing community-acquired pneumonia. Probiotics represent a new intervention target for <italic>Spn</italic> infection. Hence, the discovery and development of new potential probiotic strains are urgently needed. This study was designed to investigate the beneficial effect and mechanism of a new bacterium named <italic>Roseicella aerolata</italic> GB24<sup>T</sup> that antagonizes <italic>Spn</italic> at cellular and animal levels. The results revealed that GB24<sup>T</sup> strain inhibited the growth of <italic>Spn</italic> on sheep blood agar plates, forming inhibition circles with a diameter of 20 mm. In cultured bronchial epithelium transformed with Ad 12-SV40 2B (BEAS-2B) cells, <italic>Spn</italic> infection induced an elevation in the expression levels of interleukin-1β, interleukin-6, and tumor necrosis factor-α to 4.289 ± 0.709, 5.587 ± 2.670, and 5.212 ± 0.772 folds compared to healthy controls, respectively. Moreover, pre-infection with GB24<sup>T</sup> for 1.5 h almost eliminated the cellular inflammation caused by <italic>Spn</italic> infection. Additionally, male Sprague–Dawley rats infected with <italic>Spn</italic> were randomly allocated into two groups: GB24<sup>T</sup> pre-infection and <italic>Spn</italic> infection groups, with healthy rats as control. GB24<sup>T</sup> significantly alleviated inflammatory lung injury caused by <italic>Spn</italic> infection, which was associated with obvious changes in the abundance of gut microbiota and a trend toward enhanced secretion of short-chain fatty acids, especially acetic acid. Acetic acid was validated to be effective in alleviating inflammation due to <italic>Spn</italic> infection in cellular assays. Together, these findings highlight that GB24<sup>T</sup> strain is an important protective feature in the respiratory tract.</p>