Genetic variation of TLR4 influences immunoendocrine stress response: an observational study in cardiac surgical patients

Postoperative systemic inflammatory dysregulation and corticosteroids: a narrative review

In some patients, the inflammatory-immune response to surgical injury progresses to a harmful, dysregulated state. We posit that postoperative systemic inflammatory dysregulation forms part of a pathophysiological response to surgical injury that places patients at increased risk of complications and subsequently prolongs hospital stay. In this narrative review, we have outlined the evolution, measurement and prediction of postoperative systemic inflammatory dysregulation, distinguishing it from a healthy and self-limiting host response. We reviewed the actions of glucocorticoids and the potential for heterogeneous responses to peri-operative corticosteroid supplementation. We have then appraised the evidence highlighting the safety of corticosteroid supplementation, and the potential benefits of high/repeated doses to reduce the risks of major complications and death. Finally, we addressed how clinical trials in the future should target patients at higher risk of peri-operative inflammatory complications, whereby corticosteroid regimes should be tailored to modify not only the a priori risk, but also further adjusted in response to markers of an evolving pathophysiological response.

Investigation of TLR2 and TLR4 Polymorphisms and Sepsis Susceptibility: Computational and Experimental Approaches

Toll-like receptors (TLR) play an eminent role in the regulation of immune responses to invading pathogens during sepsis. TLR genetic variants might influence individual susceptibility to developing sepsis. The current study aimed to investigate the association of genetic polymorphisms of the TLR2 and TLR4 with the risk of developing sepsis with both a pilot study and in silico tools. Different in silico tools were used to predict the impact of our SNPs on protein structure, stability, and function. Furthermore, in our prospective study, all patients matching the inclusion criteria in the intensive care units (ICU) were included and followed up, and DNA samples were genotyped using real-time polymerase chain reaction (RT-PCR) technology. There was a significant association between TLR2 Arg753Gln polymorphisms and sepsis under the over-dominant model (p = 0.043). In contrast, we did not find a significant difference with the TLR4 Asp299Gly polymorphism with sepsis. However, there was a significant association between TLR4 Asp299Gly polymorphisms and Acinetobacter baumannii infection which is quite a virulent organism in ICU (p = 0.001) and post-surgical cohorts (p = 0.033). Our results conclude that the TLR2 genotype may be a risk factor for sepsis in adult patients.

An Analysis of the Hypothalamic-Pituitary-Adrenal Axis Functions in Cirrhotic Rats in Response to Surgical Stress

Introduction

The activation of hypothalamic-pituitary-adrenal (HPA) axis through severe diseases and stress courses leads to a rise in circulatory cortisol for an adequate response to stress. This axis is one of the important systems that involve in neuroendocrine response to the surgical stress. Hepatoadrenal syndrome that is a manifestation of adrenal insufficiency (AI) in the course of liver disease is described as insufficient production of steroid hormones mainly cortisol due to primary dysfunction of the adrenal gland or secondary malfunction of the HPA axis to provoke the adrenal gland leading to severe illness and increased mortality. Through this evidence, we presented this question as to whether cirrhotic patients have a greater mortality rate than other patients after surgery and if the HPA axis is partly responsible for this phenomenon. Also how the adrenal gland functions during surgery in cirrhotic rats. We conducted this study to assess the effect of cirrhosis on the HPA axis through surgery in cirrhotic rats by evaluating the changes in serum corticosterone level and blood sugar before, immediately, and 30 minutes after surgery.

Method

This study was performed in the animal lab approved by the Ethics Committee of Tehran University of Medical Sciences in 2014, on 25 male Wistar rats. Thioacetamide was used for induction of cirrhosis in rats with new method of monitoring weekly changes of rats' weight which had 100% success in procedure and reduction in mortality rate. Laparotomy was performed on all of the rats during 9–12 in the morning within 10–15 minutes. Laparotomy was chosen as surgical stress because of its simplicity and feasibility. Three blood samples were obtained from each rat immediately after inducing anesthesia, immediately after the conclusion of surgery, and 30 minutes after surgery. The plasma concentration of corticosterone was measured with enzyme-linked immunosorbent assay test. P value of 0.05 or less was considered as statistical significance.

Result

Cirrhotic rat group consisted of 15 rats and control group consisted of 10 rats. There was a significant difference in the mean level of corticosterone and blood sugar between the cirrhotic rat group and control group in the 3 time levels (P=0.044/P < 0.001). Pairwise comparison of mean corticosterone and blood sugar levels between case (mean: 249.359 ± 3.90) and control (mean: 262.40 ± 4.69) showed a significant difference (P=0.04, 95% CI = 0.30–25.79/P < 0.001, 95% CI = 129.62–233.96). Unlike the control group, the level of serum corticosterone was compared in the cirrhotic rat group (group 1) before, immediately, and 30 minutes after surgery, which showed a significant difference in our study (P value  = 0.005). However, this result was also significant in comparing the blood sugar in 3 time levels of surgery in the control group (P value < 0.001) but not in the cirrhotic rat group (P value = 0.233).

Conclusion

There was a significant rise in corticosterone levels during 3 time levels of surgery in cirrhotic rats; nevertheless, this elevation was significantly lower than the control group. Also the mean level of blood sugar was higher in the control group than in cirrhotic rats. However, this difference was significant in comparison with the same times of surgery between the two groups. These results approximately can substantiate our hypothesis that AI in the field of cirrhosis would also affect the response of HPA axis to stress during and after surgery that can be concomitant with higher rate of cardiovascular unsteadiness incidences, deteriorating the severity of illness and rise in mortality rate.

Green Tea Polyphenol EGCG Upregulates Tollip Expression by Suppressing Elf-1 Expression

TLR signaling is critical to innate immune system regulation; however, aberrant TLR signaling is involved in several diseases, including insulin resistance, Alzheimer's disease, and tumor metastasis. Moreover, a recent study found that TLR-4 signaling pathway inhibition might be a target for the suppression of chronic inflammatory disorders. In this article, we show that the green tea polyphenol epigallocatechin-3-O-gallate (EGCG) increases the expression of Toll interacting protein, a strong inhibitor of TLR4 signaling, by suppressing the expression of E74-like ETS transcription factor 1 (Elf-1). A mechanistic study revealed that EGCG suppressed Elf-1 expression via protein phosphatase 2A/cyclic GMP (cGMP)-dependent mechanisms. We also confirmed that orally administered EGCG and a cGMP inducer upregulated Toll interacting protein expression, increased intracellular levels of cGMP in macrophages, and suppressed Elf-1 expression. These data support EGCG and a cGMP inducer as potential candidate suppressors of TLR4 signaling.

Green Tea Polyphenol Epigallocatechin-3-gallate Suppresses Toll-like Receptor 4 Expression via Up-regulation of E3 Ubiquitin-protein Ligase RNF216

Toll-like receptor 4 (TLR4) plays an essential role in innate immunity through inflammatory cytokine induction. Recent studies demonstrated that the abnormal activation of TLR4 has a pivotal role in obesity-induced inflammation, which is associated with several diseases, including hyperinsulinemia, hypertriglyceridemia, and cardiovascular disease. Here we demonstrate that (-)-epigallocatechin-3-O-gallate, a natural agonist of the 67-kDa laminin receptor (67LR), suppressed TLR4 expression through E3 ubiquitin-protein ring finger protein 216 (RNF216) up-regulation. Our data indicate cyclic GMP mediates 67LR agonist-dependent RNF216 up-regulation. Moreover, we show that the highly absorbent 67LR agonist (-)-epigallocatechin-3-O-(3-O-methyl)-gallate (EGCG3″Me) significantly attenuated TLR4 expression in the adipose tissue. EGCG3″Me completely inhibited the high-fat/high-sucrose (HF/HS)-induced up-regulation of tumor necrosis factor α in adipose tissue and serum monocyte chemoattractant protein-1 increase. Furthermore, this agonist intake prevented HF/HS-induced hyperinsulinemia and hypertriglyceridemia. Taken together, 67LR presents an attractive target for the relief of obesity-induced inflammation.

Functional polymorphisms in toll-like receptor 4 are associated with worse outcome in acute ischemic stroke patients

Toll-like receptor-4 (TLR4) is important in neuroinflammation. Single nucleotide polymorphisms (SNPs) in TLR4, including 1063 A/G [Asp299Gly] and 1363 C/T [Thr399Ile], are associated with altered immune responses but their effect on acute ischemic stroke (AIS) outcome is unknown. We collected demographic, clinical, laboratory, radiologic, and genotype data on 113 AIS patients and performed multivariate analyses to assess associations between TLR4 SNP haplotype and either neurological outcome, infection, or inflammatory markers. In adjusted analyses, TLR4 SNPs were associated with worse outcome as well as increases in circulating leukocytes, C-reactive protein, and interleukin-1 receptor antagonist. In AIS, variations in TLR4 may influence neurological outcome (for video abstract, please see Supplemental digital content 1 file, http://links.lww.com/WNR/A274).

Potential association between TLR4 and chitinase 3-like 1 (CHI3L1/YKL-40) signaling on colonic epithelial cells in inflammatory bowel disease and colitis-associated cancer

Inflammatory bowel disease (IBD) is a group of inflammatory disorders in the small and large intestines. Several studies have proved that persistent and disregulated host/microbial interactions are required for the development of IBD. It is well known that chronic IBD is strongly associated with an increased risk of developing colorectal cancer by 0.5-1% annually, 8-10 years after the initial diagnosis. To detect the tiny dysplasia or early stage of cancer in chronic IBD patients, a tremendous amount of effort is currently directed for improving colonoscopic technology and noninvasive serological marker development. However, there is only a limited amount of data available to understand the exact mechanism of how long term chronic colitis is connected to the development of colorectal tumors. Recently, our group has identified significantly increased expression of chitinase 3-like 1 (CHI3L1) molecule in non-dysplastic mucosa from patients with IBD and remote dysplasia/cancer, compared to patients with IBD without dysplasia or healthy controls. CHI3L1 seems to contribute to the proliferation, migration, and neoplastic progression of colonic epithelial cells (CECs) under inflammatory conditions. Furthermore, the TLR4-mediated intracellular signaling cascade is likely to interact with CHI3L1 signaling in CECs. In this review article, we have concisely summarized the cellular and molecular mechanisms underlining the development of IBD and colitis-associated cancer, with particular focus on the TLR4- and CHI3L1-signaling pathways in CECs.

Attenuation of myocardial injury by HMGB1 blockade during ischemia/reperfusion is toll-like receptor 2-dependent

Genetic or pharmacological ablation of toll-like receptor 2 (TLR2) protects against myocardial ischemia/reperfusion injury (MI/R). However, the endogenous ligand responsible for TLR2 activation has not yet been detected. The objective of this study was to identify HMGB1 as an activator of TLR2 signalling during MI/R. C57BL/6 wild-type (WT) or TLR2(-/-)-mice were injected with vehicle, HMGB1, or HMGB1 BoxA one hour before myocardial ischemia (30 min) and reperfusion (24 hrs). Infarct size, cardiac troponin T, leukocyte infiltration, HMGB1 release, TLR4-, TLR9-, and RAGE-expression were quantified. HMGB1 plasma levels were measured in patients undergoing coronary artery bypass graft (CABG) surgery. HMGB1 antagonist BoxA reduced cardiomyocyte necrosis during MI/R in WT mice, accompanied by reduced leukocyte infiltration. Injection of HMGB1 did, however, not increase infarct size in WT animals. In TLR2(-/-)-hearts, neither BoxA nor HMGB1 affected infarct size. No differences in RAGE and TLR9 expression could be detected, while TLR2(-/-)-mice display increased TLR4 and HMGB1 expression. Plasma levels of HMGB1 were increased MI/R in TLR2(-/-)-mice after CABG surgery in patients carrying a TLR2 polymorphism (Arg753Gln). We here provide evidence that absence of TLR2 signalling abrogates infarct-sparing effects of HMGB1 blockade.

Association of a common TLR-6 polymorphism with coronary artery disease - implications for healthy ageing?

BACKGROUND

The pro-inflammatory status of the elderly triggers most of the age-related diseases such as cancer and atherosclerosis. Atherosclerosis, the leading cause world wide of morbidity and death, is an inflammatory disease influenced by life-style and genetic host factors. Stimuli such as oxLDL or microbial ligands have been proposed to trigger inflammation leading to atherosclerosis. It has recently been shown that oxLDL activates immune cells via the Toll-like receptor (TLR) 4/6 complex. Several common single nucleotide polymorphisms (SNPs) of the TLR system have been associated with atherosclerosis. To investigate the role of TLR-6 we analyzed the association of the TLR-6 SNP Pro249Ser with atherogenesis.

RESULTS

Genotyping of two independent groups with CAD, as well as of healthy controls revealed a significant association of the homozygous genotype with a reduced risk for atherosclerosis (odds ratio: 0.69, 95% CI 0.51-0.95, P = 0.02). In addition, we found a trend towards an association with the risk of restenosis after transluminal coronary angioplasty (odds ratio: 0.53, 95% CI 0.24-1.16, P = 0.12). In addition, first evidence is presented that the frequency of this protective genotype increases in a healthy population with age. Taken together, our results define a role for TLR-6 and its genetic variations in modulating the inflammatory response leading to atherosclerosis.

CONCLUSIONS

These results may lead to a better risk stratification, and potentially to an improved prophylactic treatment of high-risk populations. Furthermore, the protective effect of this polymorphism may lead to an increase of this genotype in the healthy elderly and may therefore be a novel genetic marker for the well-being during aging.

Why is neuroimmunopharmacology crucial for the future of addiction research?

A major development in drug addiction research in recent years has been the discovery that immune signaling within the central nervous system contributes significantly to mesolimbic dopamine reward signaling induced by drugs of abuse, and hence is involved in the presentation of reward behaviors. Additionally, in the case of opioids, these hypotheses have advanced through to the discovery of the novel site of opioid action at the innate immune pattern recognition receptor Toll-like receptor 4 as the necessary triggering event that engages this reward facilitating central immune signaling. Thus, the hypothesis of major proinflammatory contributions to drug abuse was born. This review will examine these key discoveries, but also address several key lingering questions of how central immune signaling is able to contribute in this fashion to the pharmacodynamics of drugs of abuse. It is hoped that by combining the collective wisdom of neuroscience, immunology and pharmacology, into Neuroimmunopharmacology, we may more fully understanding the neuronal and immune complexities of how drugs of abuse, such as opioids, create their rewarding and addiction states. Such discoveries will point us in the direction such that one day soon we might successfully intervene to successfully treat drug addiction. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.