scholarly journals Western diet triggers Toll-like receptor 4 signaling-induced endothelial dysfunction in female Wistar rats

2018 ◽  
Vol 315 (6) ◽  
pp. H1735-H1747 ◽  
Author(s):  
Benjamin Kramer ◽  
Lucas Martins França ◽  
Youhua Zhang ◽  
Antonio Marcus de Andrade Paes ◽  
A. Martin Gerdes ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Endothelial Dysfunction ◽  
Free Fatty Acids ◽  
Western Diet ◽  
Female Rats ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Tlr4 Signaling ◽  
Nonalcoholic Fatty Liver ◽  
Female Wistar Rats

Overconsumption of a diet rich in fat and carbohydrates, called the Western diet, is a major contributor to the global epidemic of cardiovascular disease. Despite previously documented cardiovascular protection exhibited in female rats, this safeguard may be lost under certain metabolic stressors. We hypothesized that female Wistar rats challenged by a Western diet composed of 21% fat and 50% carbohydrate (34.1% sucrose) for 17 wk would develop endothelial dysfunction via endothelial Toll-like receptor 4 (TLR4) signaling. Western diet-fed female rats exhibited dysregulation of metabolism, revealing increased body weight and abdominal fat, decreased expression of adiponectin in white adipose tissue, glucose intolerance, and impaired insulin sensitivity. Western diet exposure increased hepatic triglycerides and cholesterol alongside hepatic steatosis, categorizing nonalcoholic fatty liver disease. Moreover, a Western diet negatively affected vascular function, revealing hypertension, impaired endothelium-dependent vasorelaxation, aortic remodeling, and increased reactive oxygen species (ROS) production. Aortic protein expression of TLR4 and its downstream proteins were markedly increased in the Western diet-fed group in association with elevated serum levels of free fatty acids. In vitro experiments were conducted to test whether free fatty acids contribute to vascular ROS overproduction via the TLR4 signaling pathway. Cultured endothelial cells were stimulated with palmitate in the presence of TAK-242, a TLR4 signaling inhibitor. Palmitate-induced overgeneration of ROS in endothelial cells was abolished in the presence of TAK-242. Our data show that a Western diet induced endothelial dysfunction in female rats and suggest that endothelial TLR4 signaling may play a key role in abolishing female cardiovascular protection. NEW & NOTEWORTHY A Western diet induced elevated levels of free fatty acids, produced nonalcoholic fatty liver disease, and provoked endothelial dysfunction in female rats in association with Toll-like receptor 4 signaling-mediated vascular reactive oxygen species production. Limited consumption of a Western diet in premenopausal women may decrease their risk of cardiovascular complications.

scholarly journals Hepatocyte TLR4 triggers inter-hepatocyte Jagged1/Notch signaling to determine NASH-induced fibrosis

2021 ◽  
Vol 13 (599) ◽  
pp. eabe1692
Author(s):  
Junjie Yu ◽  
Changyu Zhu ◽  
Xiaobo Wang ◽  
KyeongJin Kim ◽  
Alberto Bartolome ◽  
...  
Keyword(s):  
Liver Fibrosis ◽  
High Fat Diet ◽  
Therapeutic Potential ◽  
Nuclear Factor Κb ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Nonalcoholic Fatty Liver ◽  
Biopsy Specimens ◽  
Nafld Activity Score ◽  
Notch Activation

Aberrant hepatocyte Notch activity is critical to the development of nonalcoholic steatohepatitis (NASH)–induced liver fibrosis, but mechanisms underlying Notch reactivation in developed liver are unclear. Here, we identified that increased expression of the Notch ligand Jagged1 (JAG1) tracked with Notch activation and nonalcoholic fatty liver disease (NAFLD) activity score (NAS) in human liver biopsy specimens and mouse NASH models. The increase in Jag1 was mediated by hepatocyte Toll-like receptor 4 (TLR4)–nuclear factor κB (NF-κB) signaling in pericentral hepatocytes. Hepatocyte-specific Jag1 overexpression exacerbated fibrosis in mice fed a high-fat diet or a NASH-provoking diet rich in palmitate, cholesterol, and sucrose and reversed the protection afforded by hepatocyte-specific TLR4 deletion, whereas hepatocyte-specific Jag1 knockout mice were protected from NASH-induced liver fibrosis. To test therapeutic potential of this biology, we designed a Jag1-directed antisense oligonucleotide (ASO) and a hepatocyte-specific N-acetylgalactosamine (GalNAc)–modified siRNA, both of which reduced NASH diet–induced liver fibrosis in mice. Overall, these data demonstrate that increased hepatocyte Jagged1 is the proximal hit for Notch-induced liver fibrosis in mice and suggest translational potential of Jagged1 inhibitors in patients with NASH.

scholarly journals Toll-Like Receptor 4 Signaling and Drug Addiction

2020 ◽  
Vol 11 ◽  
Author(s):  
Ruyan Wu ◽  
Jun-Xu Li
Keyword(s):  
Drug Addiction ◽  
Multiple Drug ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Tlr4 Signaling ◽  
Drug Classes ◽  
Downstream Effectors ◽  
Potential Efficacy ◽  
Proinflammatory Responses

The emphasis of neuronal alterations and adaptations have long been the main focus of the studies of the mechanistic underpinnings of drug addiction. Recent studies have begun to appreciate the role of innate immune system, especially toll-like receptor 4 (TLR4) signaling in drug reward-associated behaviors and physiology. Drugs like opioids, alcohol and psychostimulants activate TLR4 signaling and subsequently induce proinflammatory responses, which in turn contributes to the development of drug addiction. Inhibition of TLR4 or its downstream effectors attenuated the reinforcing effects of opioids, alcohol and psychostimulants, and this effect is also involved in the withdrawal and relapse-like behaviors of different drug classes. However, conflicting results also argue that TLR4-related immune response may play a minimal part in drug addiction. This review discussed the preclinical evidence that whether TLR4 signaling is involved in multiple drug classes action and the possible mechanisms underlying this effect. Moreover, clinical studies which examined the potential efficacy of immune-base pharmacotherapies in treating drug addiction are also discussed.

scholarly journals Key Player in Cardiac Hypertrophy, Emphasizing the Role of Toll-Like Receptor 4

2020 ◽  
Vol 7 ◽  
Author(s):  
Zheng Xiao ◽  
Bin Kong ◽  
Hongjie Yang ◽  
Chang Dai ◽  
Jin Fang ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Cardiac Hypertrophy ◽  
Intracellular Signaling ◽  
Molecular Mechanisms ◽  
New Technologies ◽  
Immune Cell ◽  
Current Knowledge ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Tlr4 Signaling

Toll-like receptor 4 (TLR4), a key pattern recognition receptor, initiates the innate immune response and leads to chronic and acute inflammation. In the past decades, accumulating evidence has implicated TLR4-mediated inflammatory response in regulation of myocardium hypertrophic remodeling, indicating that regulation of the TLR4 signaling pathway may be an effective strategy for managing cardiac hypertrophy's pathophysiology. Given TLR4's significance, it is imperative to review the molecular mechanisms and roles underlying TLR4 signaling in cardiac hypertrophy. Here, we comprehensively review the current knowledge of TLR4-mediated inflammatory response and its interaction ligands and co-receptors, as well as activation of various intracellular signaling. We also describe the associated roles in promoting immune cell infiltration and inflammatory mediator secretion, that ultimately cause cardiac hypertrophy. Finally, we provide examples of some of the most promising drugs and new technologies that have the potential to attenuate TLR4-mediated inflammatory response and prevent or reverse the ominous cardiac hypertrophy outcomes.

Hepatic Extraction of Free Fatty Acids in Pregnant and Nonpregnant Female Rats

1983 ◽  
Vol 72 (10) ◽  
pp. 1230-1232 ◽  
Author(s):  
Ruby C. Chou ◽  
Ulf W. Wiegand ◽  
David M. Soda ◽  
Gerhard Levy
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Female Rats ◽  
Hepatic Extraction

scholarly journals Toll-like receptor 4-induced endoplasmic reticulum stress contributes to impairment of vasodilator action of insulin

2015 ◽  
Vol 309 (9) ◽  
pp. E767-E776 ◽  
Author(s):  
Jeong-a Kim ◽  
Hyun-Ju Jang ◽  
Daniel H. Hwang
Keyword(s):  
Endoplasmic Reticulum ◽  
Endothelial Dysfunction ◽  
Er Stress ◽  
Saturated Fatty Acids ◽  
Chow Diet ◽  
Toll Like Receptor ◽  
Proinflammatory Response ◽  
Toll Like Receptor 4 ◽  
Aortic Endothelial Cells ◽  
Vasodilator Action

Impairment of vasodilator action of insulin is associated with endothelial dysfunction and insulin resistance. Activation of Toll-like receptor 4 (TLR4) induces proinflammatory response and endoplasmic reticulum (ER) stress. Saturated fatty acids (SFA) activate TLR4, which induces ER stress and endothelial dysfunction. Therefore, we determined whether TLR4-mediated ER stress is an obligatory step mediating SFA-induced endothelial dysfunction. Palmitate stimulated proinflammatory responses and ER stress, and this was suppressed by knockdown of TLR4 in primary human aortic endothelial cells (HAEC). Next, we examined the role of TLR4 in vasodilatory responses in intact vessels isolated from wild-type (WT, C57BL/6) and TLR4-KO mice after feeding high-fat (HFD) or normal chow diet (NCD) for 12 wk. Arterioles isolated from HFD WT mice exhibited impaired insulin-stimulated vasodilation compared with arterioles isolated from NCD WT mice. Deficiency of TLR4 was protective from HFD-induced impairment of insulin-stimulated vasodilation. There were no differences in acetylcholine (Ach)- or sodium nitroprusside (SNP)-stimulated vasodilation between the two groups. Furthermore, we examined whether ER stress is involved in SFA-induced impairment of vasodilator actions of insulin. Infusion of palmitate showed the impairment of vasodilatory response to insulin, which was ameliorated by coinfusion with tauroursodeoxycholic acid (TUDCA), an ER stress suppressor. Taken together, the results suggest that TLR4-induced ER stress may be an obligatory step mediating the SFA-mediated endothelial dysfunction.

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