AUTHOR=Hatasa Masahiro , Ohsugi Yujin , Katagiri Sayaka , Yoshida Sumiko , Niimi Hiromi , Morita Kazuki , Tsuchiya Yosuke , Shimohira Tsuyoshi , Sasaki Naoki , Maekawa Shogo , Shiba Takahiko , Hirota Tomomitsu , Tohara Haruka , Takahashi Hirokazu , Nitta Hiroshi , Iwata Takanori 

TITLE=Endotoxemia by Porphyromonas gingivalis Alters Endocrine Functions in Brown Adipose Tissue

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=10

YEAR=2021

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2020.580577

DOI=10.3389/fcimb.2020.580577

ISSN=2235-2988

ABSTRACT=<p>Improvement of obesity is important for increasing longevity. The characteristics, size, and function of adipocytes are altered in patients with obesity. Adipose tissue is not only an energy storage but also an endocrine organ. Alteration of endocrine activities in adipose tissue, among them the functional decline of brown adipose tissue (BAT), is associated with obesity. Periodontal disease is a risk factor for systemic diseases since endotoxemia is caused by periodontal bacteria. However, the effect of periodontal disease on obesity remains unclear. Thus, this study aimed to investigate the effect of endotoxemia due to <italic>Porphyromonas gingivalis</italic>, a prominent cause of periodontal disease, on the BAT. Herein, endotoxemia was induced in 12-week-old C57BL/6J mice through intravenous injection of sonicated 10<sup>8</sup> CFU of <italic>P. gingivalis</italic> (Pg) or saline (control [Co]) once. Eighteen hours later, despite no inflammatory M1 macrophage infiltration, inflammation-related genes were upregulated exclusively in the BAT of Pg mice compared with Co mice. Although no marked histological changes were observed in adipose tissues, expressions of genes related to lipolysis, <italic>Lipe</italic> and <italic>Pnpla2</italic> were downregulated after <italic>P. gingivalis</italic> injection in BAT. Furthermore, expression of <italic>Pparg</italic> and <italic>Adipoq</italic> was downregulated only in the BAT but not in the white adipose tissues, along with downregulation of <italic>Ucp1</italic> and <italic>Cidea</italic> expression, which are BAT-specific markers, in Pg mice. Microarray analysis of the BAT showed 106 differentially expressed genes between Co and Pg mice. Gene set enrichment analysis revealed that the cholesterol homeostasis gene set and PI3/Akt/mTOR signaling gene set in BAT were downregulated, whereas the TGF-β signaling gene set was enriched in Pg mice. Overall, intravenous injection of sonicated <italic>P. gingivalis</italic> altered the endocrine functions of the BAT in mice. This study indicates that endotoxemia by <italic>P. gingivalis</italic> potentially affects obesity by disrupting BAT function.</p>