The effect of oleoylethanolamide supplementation on the expression of pyroptosis pathway genes (TLR4, NLRP3, Caspase1, and IL-18) in PBMCs of obese patients with NAFLD: A double-blinded randomized controlled clinical trial

Abstract

Background and aims: Non-alcoholic fatty liver disease (NAFLD) is now the main contributor to the worldwide chronic liver diseases. Pyroptosis, a highly inflammatory programmed cell death, has recently gained interest as a pathway for hepatocyte death under liver injuries. Blocking nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3)-Inflammasome, a prominent player in the pyroptosis pathway, has been indicated to positively involve in NAFLD pathophysiology. Various animal studies show that oleoylethanolamide (OEA) supplementation can reduce nuclear factor-kappa B and some other inflammatory cytokines, which play pivotal roles in the pyroptosis pathway. This randomized controlled clinical trial (RCT) aimed to study the effects of OEA supplementation on the pyroptosis pathway in obese adults with NAFLD. Materials and Methods: The current double-blinded RCT included 65 obese adults, diagnosed for NAFLD through ultrasonography. Subjects were randomly assigned to either groups of intervention (two 125 mg OEA capsules per day) or placebo (two 125 mg starch capsules per day). The intervention lasted for 12 weeks. Subjects were also administered a personalized calorie-restricted diet based on the results of an indirect calorimetry. The anthropometric measures of the participants were gathered at the baseline and endpoint of the study. The messenger ribonucleic acid expression levels of toll-like receptor 4, NLRP3, cysteine-dependent aspartate-specific protease (Caspase) 1, and interleukin-18 genes were assessed in peripheral blood mononuclear cells, using real-time polymerase chain reaction. Threshold cycle values and fold changes were obtained for each sample. Results: The OEA group showed significant improvements in their anthropometric measures (weight, body mass index, waist circumference, hip circumference, waist to hip ratio, and waist to height ratio). All study genes indicated significant differences compared to their baseline in both groups; the expression of Caspase1, NLRP3, and IL-18 decreased, while the expression of TLR4 increased. However, no significant intergroup differences were witnessed for none of the study genes. Conclusions: The current study indicates that OEA supplementation has positive effects on NAFLD risk factors including anthropometric measures; however, significant intergroup differences were not witnessed in the pyroptosis pathway. More studies are recommended to evaluate the current findings. Key words: Non-alcoholic fatty liver disease, Oleoylethanolamide, Nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3, Pyroptosis.