scholarly journals Toll-Like Receptor 4 Promotes NO Synthesis by Upregulating GCHI Expression under Oxidative Stress Conditions in Sheep Monocytes/Macrophages

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Shoulong Deng ◽  
Kun Yu ◽  
Baolu Zhang ◽  
Yuchang Yao ◽  
Zhixian Wang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Nitric Oxide ◽  
Inflammatory Responses ◽  
Gram Negative Bacteria ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Gram Negative ◽  
Transgenic Sheep ◽  
And Oxidative Stress

Many groups of Gram-negative bacteria cause diseases that are harmful to sheep. Toll-like receptor 4 (TLR4), which is critical for detecting Gram-negative bacteria by the innate immune system, is activated by lipopolysaccharide (LPS) to initiate inflammatory responses and oxidative stress. Oxidation intermediates are essential activators of oxidative stress, as low levels of free radicals form a stressful oxidative environment that can clear invading pathogens. NO is an oxidation intermediate and its generation is regulated by nitric oxide synthase (iNOS). Guanosine triphosphate cyclohydrolase (GCHI) is the rate-limiting enzyme for tetrahydrobiopterin (BH4) synthesis, which is essential for the production of inducible iNOS. Previously, we made vectors to overexpress the sheepTLR4gene. Herein, first generation (G1) of transgenic sheep was stimulated with LPSin vivoandin vitro, and oxidative stress and GCHI expression were investigated. Oxidative injury caused by TLR4 overexpression was tightly regulated in tissues. However, the transgenic (Tg) group still secreted nitric oxide (NO) when an iNOS inhibitor was added. Furthermore, GCHI expression remained upregulated in both serum and monocytes/macrophages. Thus, overexpression of TLR4 in transgenic sheep might accelerate the clearance of invading microbes through NO generation following LPS stimulation. Additionally, TLR4 overexpression also enhances GCHI activation.

scholarly journals Loss of toll-like receptor 4 ameliorates cardiovascular dysfunction in aged mice

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Huan Liu ◽  
Shujuan Chu ◽  
Zhilin Wu
Keyword(s):  
Oxidative Stress ◽  
Insulin Sensitivity ◽  
Inflammatory Responses ◽  
Cardiac Performance ◽  
Dependent Manner ◽  
Vascular Relaxation ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Aged Mice ◽  
And Oxidative Stress

Abstract Background Toll-like receptor 4 (TLR4) is a pattern recognition receptor of the innate immune system. TLR4 contributes to many aging-related chronic diseases. However, whether TLR4 is involved in cardiovascular injury during the aging process has not been investigated. Methods The effects of TLR4 on the cardiovascular system of aged mice were investigated in TLR4−/− mice. An intraperitoneal glucose tolerance test (IPGTT) and insulin sensitivity test (IST) were conducted to evaluate global insulin sensitivity. Echocardiography was used to measure cardiac structure and performance. An isolated artery ring assay was used to measure the vasodilator function of the thoracic aorta. The inflammatory response was reflected by the serum concentration of cytokines. Results TLR4 expression increased in the hearts and aortas of mice in an age-dependent manner. Loss of TLR4 increased insulin sensitivity in aged mice. Moreover, loss of TLR4 improved cardiac performance and endothelium-dependent vascular relaxation in aged mice. Importantly, the increases in serum inflammatory cytokines and oxidative stress in the heart and aorta were also inhibited by TLR4 deficiency. Conclusion In summary, loss of TLR4 improved cardiac performance and endothelium-dependent vascular relaxation in aged mice. The reduced inflammatory responses and oxidative stress may be the reason for the protective effects of TLR4 deficiency during aging. Our study indicates that targeting TLR4 is a potential therapeutic strategy for preventing aging-related cardiovascular disease.

scholarly journals Effect of Spaceflight on Ability of Monocytes To Respond to Endotoxins of Gram-Negative Bacteria

2008 ◽  
Vol 15 (10) ◽  
pp. 1523-1528 ◽  
Author(s):  
Indreshpal Kaur ◽  
Elizabeth R. Simons ◽  
Asha S. Kapadia ◽  
C. Mark Ott ◽  
Duane L. Pierson
Keyword(s):  
Space Shuttle ◽  
Space Station ◽  
Gram Negative Bacteria ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Gram Negative ◽  
Time Points ◽  
Control Subjects ◽  
Intracellular Cytokines ◽  
Blood Specimens

ABSTRACT Astronauts live and work in relatively crowded, confined environments on the Space Shuttle and the International Space Station. They experience a unique set of stressors that contribute to a diminishment of many immune responses. This study investigated the ability of the shuttle crew members' monocytes to respond to gram-negative endotoxin that they could encounter during infections. Blood specimens were collected from 20 crew members and 15 control subjects 10 days before launch, 3 to 4 h after landing, and 15 days after landing and from crew members during their annual medical examination at 6 to 12 months after landing. When challenged with gram-negative endotoxin, the crew member's monocytes collected at all three time points produced lower levels of interleukin-6 (IL-6) and IL-1β and higher levels of IL-1ra and IL-8 compared to those of control subjects. Cytokines were assessed by measuring the number of cells positive for intracellular cytokines. These values returned to normal 6 to 12 months after landing, except for IL-1ra, which was still higher (five- to sixfold) than in controls. This phenomenon was accompanied by an increased expression of Toll-like receptor 4 and decreased expression of CD14 on the crew members' monocytes at all time points. There were also increased levels of the lipopolysaccharide binding protein in the plasma of the crew members 3 to 4 h and 15 days after landing. This study shows that spaceflight-associated factors (in-flight and preflight) modulate the response of monocytes to gram-negative endotoxins.

Increased Expressions of Toll-Like Receptor 4 on Platelet Are Related to Type of Bacteria and Disease Severity in Patients with Sepsis

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 5365-5365
Author(s):  
Liping Ma ◽  
Xiu-Ju Wang ◽  
Da-Nian Nie ◽  
Yi-Qing Li ◽  
Shuang-Fen Xie ◽  
...  
Keyword(s):  
Blood Platelets ◽  
Inflammatory Cells ◽  
Gram Negative Bacteria ◽  
Toll Like Receptor ◽  
Microbial Infection ◽  
Toll Like Receptor 4 ◽  
Gram Positive ◽  
Severe Problem ◽  
Gram Negative ◽  
Gram Positive Bacteria

Abstract Early diagnosis and treatment of patients with sepsis remain a common and severe problem, especially in leukopenic patients.. Toll-like receptor-4 (TLR4) plays a crucial role in immunity as the first defenses system against microbial infection through binding gram-negative bacterial LPS. Blood platelets are not only involved in hemostasis, they also have many features of classic inflammatory cells. The expression of TLR4 on platelet in patients with sepsis, including gram-positive bacteria and gram-negative bacteria, is not known. Studying the differences between them, we investigated whether the expressions of TLR4 on platelet were associated with platelet activation, serum TNF-a and endotoxin levels in patients with sepsis, 8 patients of them with gram-positive bacteria and 15 patients of them with gram-negative bacteria. The number of platelet and function of coagulation were normal before infecting. Comparing with the heath subjects, the expressions of TLR4 and P-selectin on platelets, the levels of serum TNF-a and endotoxin were higher (P<0.05),and there was a positive correlation was observed between TLR4 and P-selectin, TNF-a, endotoxin respectively, among the gram-negative bacterial subjects. The phenomena were not found among the gram-positive bacterial subjects. In addition, among the gram-negative bacterial subjects, the expression of TLR4 was higher in patients with decreased number of platelets than with normal number of platelets. These results suggest that increased TLR4 on platelet might be an important early sign of gram-negative bacteria in patient with sepsis, it contributes to platelet activating, the inflammatory process and disease activity in infecting host. Above has be doing in more patients with positive blood bacteria culture in our Lab.

Ablation of toll-like receptor 4 mitigates cardiac mitochondrial dysfunction in hyperhomocysteinemia

2017 ◽  
Vol 95 (11) ◽  
pp. 1369-1375 ◽  
Author(s):  
Nevena Jeremic ◽  
Gregory J. Weber ◽  
Suresh C. Tyagi
Keyword(s):  
Oxidative Stress ◽  
Endothelial Cell ◽  
Mitochondrial Dysfunction ◽  
Mitochondrial Fission ◽  
Cell Loss ◽  
Toll Like Receptor ◽  
Endothelial Cell Loss ◽  
Toll Like Receptor 4 ◽  
Immune Response Pathway ◽  
And Oxidative Stress

Hyperhomocysteinemia (HHcy) is a risk factor for adverse cardiovascular events; however, the mechanism for development of this disease is still unknown. Toll-like receptor 4 (TRL4) is a molecule involved in the immune response pathway and is quickly becoming a receptor of interest in the field of hypertension. In this study, we hypothesized that ablation of TLR4 mitigates cardiac mitochondrial dysfunction in a model of HHcy. Five strains of mice (C57BL/6J, CBS+/−, C3H, CBS+/−/C3H, and C3H/HeOuJ) 10–12 weeks old were utilized. We found that HHcy causes heart hypertrophy and promotes oxidative stress while mice with HHcy and inactivated TLR4 showed significant improvement in examined parameters. A dominance of endothelial cell mitochondrial fission over mitochondrial fusion in HHcy and oxidative stress was observed, which may explain the endothelial cell loss and dysfunction that contributes to inward cardiac remodeling.

scholarly journals Central Role of Toll-Like Receptor 4 Signaling and Host Defense in Experimental Pneumonia Caused by Gram-Negative Bacteria

2005 ◽  
Vol 73 (1) ◽  
pp. 532-545 ◽  
Author(s):  
Jill R. Schurr ◽  
Erana Young ◽  
Pat Byrne ◽  
Chad Steele ◽  
Judd E. Shellito ◽  
...  
Keyword(s):  
Gene Expression ◽  
Adaptor Protein ◽  
Mouse Strains ◽  
Gram Negative Bacteria ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Tlr4 Signaling ◽  
Gram Negative ◽  
Experimental Pneumonia

ABSTRACT Toll-like receptor 4 (TLR4) has been identified as a receptor for lipopolysaccharide. However, the precise role of TLR4 in regulating gene expression in response to an infection caused by gram-negative bacteria has not been fully elucidated. The role of TLR4 signaling in coordinating gene expression was assessed by gene expression profiling in lung tissue in a mouse model of experimental pneumonia with a low-dose infection of Klebsiella pneumoniae. We analyzed four mouse strains: C57BL/6 mice, which are resistant to bacterial dissemination; 129/SvJ mice, which are susceptible; C3H/HeJ mice, which are susceptible and have defective TLR4 signaling; and their respective control strain, C3H/HeN (intermediate resistance). At 4 h after infection, C57BL/6 and C3H/HeN mice demonstrated the greatest number of genes, with 67 shared induced genes which were TLR4 dependent and highly associated with the resistance phenotype. These genes included cytokine and chemokine genes required for neutrophil activation or recruitment, growth factor receptors, MyD88 (a critical adaptor protein for TLR signaling), and adhesion molecules. TLR4 signaling accounted for over 74% of the gene expression in the C3H background. These data suggest that early TLR4 signaling controls the vast majority of gene expression in the lung in response to an infection caused by gram-negative bacteria and that this subsequent gene expression determines survival of the host.

Sign in / Sign up

Export Citation Format

Share Document