Adipocyte mTORC1 deficiency promotes adipose tissue inflammation and NLRP3 inflammasome activation via oxidative stress and de novo ceramide synthesis[S]

• Published in: Journal of lipid research Vol. 58; no. 9; pp. 1797 - 1807
• Main Authors: Chimin, Patricia, Andrade, Maynara L., Belchior, Thiago, Paschoal, Vivian A., Magdalon, Juliana, Yamashita, Alex S., Castro, Érique, Castoldi, Angela, Chaves-Filho, Adriano B., Yoshinaga, Marcos Y., Miyamoto, Sayuri, Câmara, Niels O., Festuccia, William T.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2017; Journal of Lipid Research; The American Society for Biochemistry and Molecular Biology; Elsevier
• Subjects: Acetylcysteine; Adipocytes; Adipocytes - drug effects; Adipocytes - metabolism; Adipocytes - pathology; Adipose tissue; Adipose Tissue - drug effects; Adipose Tissue - metabolism; Adipose Tissue - pathology; Animals; Body mass; Ceramide; Ceramides - biosynthesis; Diet, High-Fat - adverse effects; Fatty liver; Glucose - metabolism; High fat diet; Homeostasis; Homeostasis - drug effects; IL-1β; Inflammasomes; Inflammasomes - metabolism; Inflammation; Insulin; Insulin resistance; Leukocytes (neutrophilic); Lipid peroxidation; Lymphocytes B; Macrophages; mechanistic target of rapamycin complex 1; Mechanistic Target of Rapamycin Complex 1 - deficiency; Mechanistic Target of Rapamycin Complex 2 - deficiency; Mice; Mice, Inbred C57BL; Monocyte chemoattractant protein; Monocyte chemoattractant protein 1; NLR Family, Pyrin Domain-Containing 3 Protein - metabolism; nucleotide oligomerization domain-like receptor pyrin domain-containing 3; Oligomerization; Oxidative stress; Oxidative Stress - drug effects; Pyrin protein; Rapamycin; Rodents; Rosiglitazone; Steatosis; TOR protein; Tumor necrosis factor-α; nucleotide oligomerization domain-like receptor pyrin domain-containing 3; insulin resistance; mechanistic target of rapamycin complex 1
• ISSN: 0022-2275; 1539-7262
• DOI: 10.1194/jlr.M074518

Mechanistic target of rapamycin complex (mTORC)1 activity is increased in adipose tissue of obese insulin-resistant mice, but its role in the regulation of tissue inflammation is unknown. Herein, we investigated the effects of adipocyte mTORC1 deficiency on adipose tissue inflammation and glucose homeostasis. For this, mice with adipocyte raptor deletion and controls fed a chow or a high-fat diet were evaluated for body mass, adiposity, glucose homeostasis, and adipose tissue inflammation. Despite reducing adiposity, adipocyte mTORC1 deficiency promoted hepatic steatosis, insulin resistance, and adipose tissue inflammation (increased infiltration of macrophages, neutrophils, and B lymphocytes; crown-like structure density; TNF-α, interleukin (IL)-6, and monocyte chemoattractant protein 1 expression; IL-1β protein content; lipid peroxidation; and de novo ceramide synthesis). The anti-oxidant, N-acetylcysteine, partially attenuated, whereas treatment with de novo ceramide synthesis inhibitor, myriocin, completely blocked adipose tissue inflammation and nucleotide oligomerization domain-like receptor pyrin domain-containing 3 (NLRP3)-inflammasome activation, but not hepatic steatosis and insulin resistance induced by adipocyte raptor deletion. Rosiglitazone treatment, however, completely abrogated insulin resistance induced by adipocyte raptor deletion. In conclusion, adipocyte mTORC1 deficiency induces adipose tissue inflammation and NLRP3-inflammasome activation by promoting oxidative stress and de novo ceramide synthesis. Such adipose tissue inflammation, however, is not an underlying cause of the insulin resistance displayed by these mice.