Chitin enhances obese inflammation ex vivo.
Infection has been implicated as a co-risk factor for obesity, but the mechanism remains uncertain. Elevated levels of plasma chitinase 3-like 1 (CHI3L1) are found in obese individuals. Since CHI3L1 is produced by activated immune cells including macrophages and recognizes microbial N-acetylglucosamine polymer (chitin), we asked whether the plasma CHI3L1 protein change in obese individuals might alter their innate immune response to chitin. Thirty-six subjects (15 obese and 21 non-obese), ages 18-30 years, were recruited. Peripheral blood mononuclear cells (PBMCs) were cultured with chitin microparticles (CMP; 1-10 μm) for 24h; tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), and CHI3L1 in the culture supernatants were measured. We chose CMP, since neither large chitin beads (40-100 μm), chitosan microparticles (1-10 μm), nor soluble chitin induced the cytokine/CHI3L1 production by PBMCs isolated from non-obese PBMCs ex vivo. We found that the quantity of IL-6, but not TNF-α or CHI3L1, induced by CMP was significantly correlated with plasma IL-6, BMI, waist/hip circumferences, fasting plasma insulin, and insulin resistance. These findings suggest that chitin, a substrate of CHI3L1, further promotes obese inflammation in a size- and chemical composition- dependent manner.
Department of Exercise Science and Health Promotion, Florida Atlantic University, Boca Raton, FL, United States. Electronic address: chuang5@fau.edu.
Chun-Jung
CJ
Huang
School of Pharmacy, University of Southern California, Los Angeles, CA, United States.
Kathleen N
KN
Beasley
Department of Health and Human Performance, Virginia Commonwealth University, Richmond, VA, United States.
Edmund O
EO
Acevedo
Department of Health and Human Performance, Virginia Commonwealth University, Richmond, VA, United States.
Robert L
RL
Franco
Children's Foundation Research Institute, Departments of Pediatrics and Preventive Medicine, University of Tennessee Health Science Center, Memphis, TN, United States.
Tamekia L
TL
Jones
Department of Exercise Science and Health Promotion, Florida Atlantic University, Boca Raton, FL, United States.
David C
DC
Mari
Department of Biomedical Science, College of Medicine, Florida Atlantic University, Boca Raton, FL, United States.
Yoshimi
Y
Shibata
D054392:Adipokines / Q000096:biosynthesis / Q000097:blood; D000293:Adolescent; D000328:Adult; D000886:Anthropometry; D002686:Chitin / Q000276:immunology*; D000071451:Chitinase-3-Like Protein 1; D016207:Cytokines / Q000096:biosynthesis / Q000097:blood; D005260:Female; D006801:Humans; D007249:Inflammation / Q000276:immunology* / Q000378:metabolism; D018836:Inflammation Mediators / Q000097:blood; D037102:Lectins / Q000096:biosynthesis / Q000097:blood; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000276:immunology; D008070:Lipopolysaccharides / Q000276:immunology; D008297:Male; D009765:Obesity / Q000276:immunology* / Q000378:metabolism; D055815:Young Adult
D054392:Adipokines; C084533:CHI3L1 protein, human; D000071451:Chitinase-3-Like Protein 1; D016207:Cytokines; D018836:Inflammation Mediators; D037102:Lectins; D008070:Lipopolysaccharides; D002686:Chitin