1930-P: The Knockdown of TRIL in POMC-Expressing Neurons Reduces Body Adiposity and Ameliorates Leptin Responsiveness

Abstract

Chronic HFD intake induces low-grade inflammation in the hypothalamus, which is characterized by proinflammatory cytokine overproduction. This process occurs, at least in part, via TLR4 activation by circulant saturated fatty acids. The TLR4 signaling in the brain is mediated by the TLR4 interactor with leucine-rich repeats (TRIL), an upstream accessory protein. Our main purpose was to determine the putative involvement of TRIL in diet-induced hypothalamic inflammation. We employed male, 8-12 week-old C57BL and POMCCRE mice fed on chow or HFD. The mRNA levels in the hypothalamus were measured by RT-PCR, western blot analyses was used for determination of protein content and immunofluorescence microscopy for evaluate the distribution of TRIL in arcuate nucleus (ARC) of hypothalamus and leptin signaling in POMC-expressing neurons. Finally, bilateral viral injections were performed to non-specific knockdown of TRIL in ARC using shRNA-based lentivirus and Cre-dependent AAV to knockdown TRIL specifically in POMC neurons. The non-specific knockdown of TRIL in the ARC of mice fed on HFD attenuated body weight gain despite no alterations in food intake, improved glucose homeostasis and increased energy expenditure. Moreover, nlrp3, il1β and hspa5 mRNA expression were decreased upon knockdown of TRIL. POMC-specific knockdown of TRIL reduced body fat with no changes in food intake or body weight gain in mice fed on HFD for 8 weeks. The inhibition of TRIL in POMC neurons resulted in a trend of improved leptin signaling in those neurons. We also found increased expression of thermogenic genes in the iBAT and improved fasting glucose. POMC-specific inhibition of TRIL in mice fed on HFD for long-term (24 weeks) did not prevent POMC loss or diminishes cleaved-caspase 3 in ARC. Collectively our results suggest that TRIL is involved in the TLR4-mediated early response to dietary fats and TRIL targeting counteract hypothalamic inflammation and partially restores metabolic homeostasis. Disclosure A. Moura-Assis: None. J. Junior: None. J.M. Gaspar: None. L. Velloso: None. P.S. Nogueira: None. Funding São Paulo Research Foundation (2016/01245-5)