Local free fatty acids trigger the expression of lipopolysaccharide-binding protein in murine white adipose tissue

Manami Seki; Akiho Miwa; Fumina Ohsaka; Yugo Karatsu; Takeshi Tsuruta; Shingo Hino; Tatsuya Morita; Kei Sonoyama

doi:10.12938/bmfh.2021-061

Local free fatty acids trigger the expression of lipopolysaccharide-binding protein in murine white adipose tissue

Biosci Microbiota Food Health. 2022;41(2):54-65. doi: 10.12938/bmfh.2021-061. Epub 2022 Jan 28.

Authors

Manami Seki¹, Akiho Miwa¹, Fumina Ohsaka², Yugo Karatsu², Takeshi Tsuruta³, Shingo Hino⁴, Tatsuya Morita⁴, Kei Sonoyama⁵

Affiliations

¹ Graduate School of Life Science, Hokkaido University, Kita-9, Nishi-9, Kita-ku, Sapporo 060-8589, Japan.
² Graduate School of Agriculture, Hokkaido University, Kita-9, Nishi-9, Kita-ku, Sapporo 060-8589, Japan.
³ Graduate School of Environmental and Life Science, Okayama University, 2-1-1 Tsushima-Naka, Kita-ku, Okayama-shi, Okayama 700-8530, Japan.
⁴ College of Agriculture, Academic Institute, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka-shi, Shizuoka 422-8529, Japan.
⁵ Research Faculty of Agriculture, Hokkaido University, Kita-9, Nishi-9, Kita-ku, Sapporo 060-8589, Japan.

Abstract

Although lipopolysaccharide (LPS)-binding protein (LBP) is an acute-phase protein mainly produced by hepatocytes, it has also been proposed to be a pro-inflammatory adipokine. Obesity and the consumption of a high-fat diet (HFD) are reportedly associated with elevated levels of LPS in plasma and free fatty acids (FFAs) in white adipose tissue (WAT). We examined whether circulating LPS or local FFAs are responsible for the HFD-induced increase of LBP in WAT. Male C57BL/6J mice were fed either a normal-fat diet (NFD) or an HFD. The mRNA levels in the liver and mesenteric WAT (mWAT), total FFA content in mWAT, and LBP and LPS concentrations in plasma were determined. The Lbp mRNA level in mWAT was higher in mice fed the HFD than in those fed the NFD for 3, 7, or 28 days or 14 weeks, whereas the hepatic Lbp mRNA level did not differ between the groups. The Lbp mRNA level in mWAT was also increased by the HFD in germ-free mice, which do not have gut microbiota, the source of LPS. The plasma LPS level did not show a significant correlation with the mWAT Lbp mRNA level. The total FFA content in mWAT was higher in mice fed the HFD than in those fed the NFD and positively correlated with the Lbp mRNA level. Supplementation with palmitic acid increased the Lbp mRNA level in 3T3-L1 adipocytes. We propose that local FFAs, but not circulating LPS, are the trigger for increased Lbp expression in mWAT of mice fed the HFD.

Keywords: high-fat diet; inflammation; lipopolysaccharide-binding protein; white adipose tissue.