Background and Aims In general, physical activity (PA) and nonalcoholic fatty liver disease (NAFLD) have an inverse association. However, studies assessing the impact of the widely accepted Physical Activity Guidelines for Americans (PA Guidelines) on NAFLD are lacking. Approach and Results We performed a serial, cross‐sectional analysis among adults by using the 2007‐2016 US National Health and Nutrition Examination Survey. NAFLD and advanced fibrosis were defined by using various noninvasive panels. A PA questionnaire assessed the leisure‐time PA, occupation‐related PA, transportation‐related PA, and total sitting time as sedentary behavior. PA was categorized according to the PA Guidelines. Of the 24,588 individuals (mean age, 47.4 years; 47.9% males), leisure‐time PA (≥150 minutes per week) demonstrated 40% lower odds of NAFLD, whereas transportation‐related PA was associated with a 33% risk reduction in NAFLD. Analysis of total PA and sitting times simultaneously showed a dose‐response association between sitting time and NAFLD (P for trend < 0.001). Compliance with the PA Guidelines was lower in individuals with NAFLD versus those without NAFLD. The trends in compliance with the PA Guidelines for any type of PA remained stable in individuals with NAFLD except for a downtrend in transportation‐related PA. In contrast, an improvement in compliance with the PA Guidelines for leisure time was noted in the cohort without NAFLD. Although PA demonstrated a 10% stronger association with risk reduction of NAFLD in women, women showed a lower tendency of meeting the PA Guidelines. Trends in total sitting time increased significantly regardless of NAFLD status. Conclusions Sedentary behavior emerged as an independent predictor of NAFLD. Overall compliance with the PA Guidelines was lower in the cohort with NAFLD, with sex‐ and ethnicity‐based differences. Implementation of these observations in clinical practice may improve our understanding as well as clinical outcomes.

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the developed world, with a global prevalence of around 25%. NAFLD is considered to be the hepatic manifestation of metabolic syndrome and is strongly associated with obesity, insulin resistance and dyslipidemia. Insulin resistance plays a pivotal role in the development of NAFLD-related dyslipidemia, which ultimately increases the risk of premature cardiovascular diseases, a leading cause of morbidity and mortality in patients with NAFLD. Insulin affects hepatic glucose and lipid metabolism by hepatic or extrahepatic pathways. Aside from insulin resistance, several other factors also contribute to the pathogenesis of atherogenic dyslipidemia in patients with NAFLD. These include diet composition, gut microbiota and genetic factors, to name a few. The identification of potentially modifiable risk factors of NAFLD is of importance, so as to target those who may benefit from lifestyle changes and to help develop targeted therapies that decrease the risk of cardiovascular diseases in patients with NAFLD. Citation of this article: Akhtar DH, Iqbal U, Vazquez-Montesino LM, Dennis BB, Ahmed A. Pathogenesis of insulin resistance and atherogenic dyslipidemia in nonalcoholic fatty liver disease.Abbreviations: DNL, de novo lipogenesis; NAFLD, nonalcoholic fatty liver disease; SIBO, small intestinal bacterial overgrowth.

INTRODUCTION: Higher levels of thyroid-stimulating hormone (TSH) in the euthyroid state can negatively affect the metabolic health, including nonalcoholic fatty liver disease (NAFLD). We studied the effect of TSH levels in the setting of normal levels of thyroid hormone on all-cause and cause-specific mortality stratified by NAFLD status. METHODS: The National Health and Nutrition Examination Survey (NHANES) III from 1988 to 1994 and NHANES III-linked mortality data through 2015 were used. NAFLD was defined as ultrasonographically diagnosed hepatic steatosis without coexisting liver diseases. Subclinical hypothyroidism was defined as a TSH level over 4.5 mIU/L and “low-normal” thyroid function as higher TSH level (2.5–4.5 mIU/L) within the euthyroid reference range. The Cox proportional hazard model analyzed the all-cause mortality and cause-specific mortality. RESULTS: In a multivariate logistic regression analysis, individuals with low thyroid function demonstrated an association with NAFLD in a dose-dependent manner. During a median follow-up of 23 years, low thyroid function was associated with increased all-cause mortality only in the univariate model. Low thyroid function was associated with a higher risk for all-cause mortality in individuals with NAFLD and not in those without NAFLD. Furthermore, low thyroid function was associated with a higher risk for cardiovascular mortality in the entire population and among those with NAFLD but demonstrated no association with the non-NAFLD group. DISCUSSION: In this large nationally representative sample of American adults, low thyroid function was associated with NAFLD and a predictor of higher risk for all-cause and cardiovascular mortality in individuals with NAFLD.

Background & Aims Healthy diet has been recommended for nonalcoholic fatty liver disease (NAFLD), although it is not clear whether improving diet quality can prevent mortality. We aim to assess the impact of quality of diet on NAFLD and mortality in subjects with and without NAFLD. Methods We performed cohort study using the Third National Health and Nutrition Examination Survey from 1988 to 1994 and linked mortality data through 2015. We used the Healthy Eating Index (HEI) scores to define diet quality, with higher HEI scores (Q4) indicating better adherence to dietary recommendations. NAFLD was defined as ultrasonographic hepatic steatosis. Results Multivariate analysis showed that subjects with higher diet quality were inversely associated with NAFLD in a dose‐dependent manner. During the median follow‐up of 23 years, having a higher diet quality was associated with reduction in risk of all‐cause mortality in the age, sex, Race/ethnicity‐adjusted hazard ratio (HR) (Q4, HR: 0.60, 95% CI: 0.52‐0.68) and the multivariate model (Q4, HR: 0.81, 95% CI: 0.71‐0.92). Higher diet quality was associated with a lower risk for all‐cause mortality in subjects without NAFLD; however, this protective association with diet quality was not noted in those with NAFLD. Furthermore, a high diet quality was associated with a lower risk for cancer‐related mortality in the total population and among those without NAFLD. This association was not noted in those with NAFLD. Conclusions High diet quality was inversely associated with NAFLD and was positively associated with a lower risk for cancer‐related and all‐cause mortality in those without NAFLD.

GPR15 is a chemoattractant receptor that facilitates colon homing of regulatory and effector CD4 + T cells in health and colitis. The molecular mechanisms that control GPR15 expression are not fully known. Here we report the presence of two highly conserved aryl hydrocarbon receptor (AHR) binding sequences in a 3′ enhancer of GPR15, leading us to investigate AHR function in regulating GPR15 expression. Using luciferase reporter assays, we show that AHR activation increased GPR15 expression and requires both the AHR binding sites. Consistent with a transcriptional regulatory role, treatment with AHR agonists induce GPR15 expression on human CD4 + T cells. Using AHR-deficient mice, we demonstrate that the lack of AHR signaling drastically reduces GPR15 expression on effector/memory and Foxp3 + CD4 + T cells. In mixed bone marrow chimeras of AHR-deficient and wildtype cells, GPR15 expression was similarly diminished on AHR-deficient CD4 + effector/memory and regulatory T cells in the colon and small intestine. Furthermore, administration of AHR agonists upregulated GPR15 expression on CD4 + effector/memory T cells and increased their homing capability, especially to the colon. Collectively, our studies reveal a novel function of the AHR in regulation of GPR15 expression and increased colon trafficking of CD4 + T cells expressing GPR15.