Atorvastatin suppresses LPS-induced rapid upregulation of Toll-like receptor 4 and its signaling pathway in endothelial cells

Statins in Mitigating Anticancer Treatment-Related Cardiovascular Disease

Certain anticancer therapies inevitably increase the risk of cardiovascular events, now the second leading cause of death among cancer patients. This underscores the critical need for developing effective drugs or regimens for cardiovascular protection. Statins possess properties such as antioxidative stress, anti-inflammatory effects, antifibrotic activity, endothelial protection, and immune modulation. These pathological processes are central to the cardiotoxicity associated with anticancer treatment. There is prospective clinical evidence confirming the protective role of statins in chemotherapy-induced cardiotoxicity. Numerous preclinical studies have demonstrated that statins can ameliorate heart and endothelial damage caused by radiotherapy, although clinical studies are scarce. In the animal models of trastuzumab-induced cardiomyopathy, statins provide protection through anti-inflammatory, antioxidant, and antifibrotic mechanisms. In animal and cell models, statins can mitigate inflammation, endothelial damage, and cardiac injury induced by immune checkpoint inhibitors. Chimeric antigen receptor (CAR)-T cell therapy-induced cardiotoxicity and immune effector cell-associated neurotoxicity syndrome are associated with uncontrolled inflammation and immune activation. Due to their anti-inflammatory and immunomodulatory effects, statins have been used to manage CAR-T cell therapy-induced immune effector cell-associated neurotoxicity syndrome in a clinical trial. However, direct evidence proving that statins can mitigate CAR-T cell therapy-induced cardiotoxicity is still lacking. This review summarizes the possible mechanisms of anticancer therapy-induced cardiotoxicity and the potential mechanisms by which statins may reduce related cardiac damage. We also discuss the current status of research on the protective effect of statins in anticancer treatment-related cardiovascular disease and provide directions for future research. Additionally, we propose further studies on using statins for the prevention of cardiovascular disease in anticancer treatment.

The impact of lipopolysaccharide on cerebrovascular function and cognition resulting from obesity-induced gut dysbiosis

Obesity is a worldwide epidemic coinciding with a concomitant increase in the incidence of neurodegenerative diseases, particularly dementia. Obesity is characterised by increased adiposity, chronic low-grade systemic inflammation, and oxidative stress, which promote endothelial dysfunction. Endothelial dysfunction reduces cerebrovascular function leading to reduced cerebral blood flow and, eventually, cognitive decline, thus predisposing to a neurodegenerative disease. Obesity is also characterised by gut dysbiosis and a subsequent increase in the lipopolysaccharide which increasingly activates toll-like receptor 4 (TLR4) and further promotes chronic low-grade systemic inflammation. This also disrupts the crosstalk within the gut-brain axis, thus influencing the functions of the central nervous system, including cognition. However, the mechanisms by which obesity-related increases in oxidative stress, inflammation and endothelial dysfunction are driven by, or associated with, increased systemic lipopolysaccharide leading to reduced cerebrovascular function and cognition, beyond normal ageing, have not been elucidated. Hence, this review examines how increased concentrations of lipopolysaccharide and the subsequent increased TLR4 activation observed in obesity exacerbate the development of obesity-induced reductions in cerebrovascular function and cognition.

Regulation of toll-like receptor (TLR) signaling pathways in atherosclerosis: from mechanisms to targeted therapeutics

Atherosclerosis, one of the life-threatening cardiovascular diseases (CVDs), has been demonstrated to be a chronic inflammatory disease, and inflammatory and immune processes are involved in the origin and development of the disease. Toll-like receptors (TLRs), a class of pattern recognition receptors that trigger innate immune responses by identifying pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs), regulate numerous acute and chronic inflammatory diseases. Recent studies reveal that TLRs have a vital role in the occurrence and development of atherosclerosis, including the initiation of endothelial dysfunction, interaction of various immune cells, and activation of a number of other inflammatory pathways. We herein summarize some other inflammatory signaling pathways, protein molecules, and cellular responses associated with TLRs, such as NLRP3, Nrf2, PCSK9, autophagy, pyroptosis and necroptosis, which are also involved in the development of AS. Targeting TLRs and their regulated inflammatory events could be a promising new strategy for the treatment of atherosclerotic CVDs. Novel drugs that exert therapeutic effects on AS through TLRs and their related pathways are increasingly being developed. In this article, we comprehensively review the current knowledge of TLR signaling pathways in atherosclerosis and actively seek potential therapeutic strategies using TLRs as a breakthrough point in the prevention and therapy of atherosclerosis.

Atorvastatin protects against cyclophosphamide-induced thyroid injury in rats via modulation of JNK/ ERK/ p38 MAPK signaling pathway

BACKGROUND

Cancer chemotherapy is associated with various tissue toxicities that limit its use. Cyclophosphamide (CYC) is one of the most commonly used antineoplastic and immunosuppressive agent. Thyroid dysfunction is a critical side effect of anticancer drugs. Atorvastatin (ATV) is antihyperlipedemic drug with different tissue protective activities. The aim of this study was to determine the potential protective effect of ATV against CYC-induced thyroid injury in rats.

METHODS

ATV was administered in the presence and absence of CYC. Thirty-two adult Wistar rats were randomly divided into four groups: control group, ATV group (20 mg/kg/day, p.o. for 14 day), CYC group (200 mg/kg, i.p. on day 9) and ATV/CYC group. Triiodothyronine (T3), thyroxine (T4), reduced glutathione (GSH), malondialdehyde (MDA), total nitrite/nitrate (NOx), p38 mitogen-activated protein kinase (P38MAPK), extracellular signal-regulated kinase (ERK) and c-Jun N-terminal Kinase (JNK) were measured. In addition, thyroid histopathology and caspase 3 immunohistochemistry were performed.

RESULTS

CYC significantly increased thyroid MDA, NOx, P38MAPK, ERK and JNK with decrease in GSH, T3 and T4 levels. Histopathological features of thyroid lesions and increased caspase 3 immune expression were appeared. ATV significantly normalized distributed oxidative, inflammatory and apoptotic indicators, resulting in an improvement of histopathological features and reduction of caspase 3 immunoexpression.

CONCLUSION

These findings suggest that ATV protects against CYC-induced thyroid injury by regulating the JNK/ERK/p38-MAPK signaling pathway.

Involvement of Oxidative Stress in Protective Cardiac Functions of Calprotectin

Calprotectin (CLP) belonging to the S-100 protein family is a heterodimeric complex (S100A8/S100A9) formed by two binding proteins. Upon cell activation, CLP stored in neutrophils is released extracellularly in response to inflammatory stimuli and acts as damage-associated molecular patterns (DAMPs). S100A8 and S100A9 possess both anti-inflammatory and anti-bacterial properties. The complex is a ligand of the toll-like receptor 4 (TLR4) and receptor for advanced glycation end (RAGE). At sites of infection and inflammation, CLP is a target for oxidation due to its co-localization with neutrophil-derived oxidants. In the heart, oxidative stress (OS) responses and S100 proteins are closely related and intimately linked through pathophysiological processes. Our review summarizes the roles of S100A8, S100A9 and CLP in the inflammation in relationship with vascular OS, and we examine the importance of CLP for the mechanisms driving in the protection of myocardium. Recent evidence interpreting CLP as a critical modulator during the inflammatory response has identified this alarmin as an interesting drug target.

Cultured Human Uveal Melanocytes Express/secrete CXCL1 and CXCL2 Constitutively and Increased by Lipopolysaccharide via Activation of Toll-like Receptor 4

Purpose: Lipopolysaccharide (LPS) can activate Toll-like receptor 4 (TLR4) and increase the expression of CXCL1 and CXCL2, the potent neutrophils chemoattractants, in various cell types. These effects have not been previously reported in the uveal melanocytes. This study was designed to investigate the effects of LPS on the activation of TLR4 and expression of CXCL1/CXCL2 in cultured human uveal melanocytes and the relevant signal pathways.Methods: Effects of LPS on the expression of TLR4 were tested using real-time PCR, flow cytometry and fluorescence immunostaining. Effects of LPS-induced expression/secretion of CXCL1/CXCL2 were studied using real-time PCR in cell lysates and ELISA in conditioned media of cultured uveal melanocytes. Activated NF-κB and phosphorylated MAPK signals were tested in cells with and without LPS treatment using flow cytometry. Effects of various signal inhibitors on p38, ERK1/2, JNK1/2 and NF-κB on the secretion of CXCL1/CXCL2 were tested by ELISA. The effects of neutralized antibodies of CXCL1/CXCL2 on the severity of LPS-induced uveitis were tested in a mouse model.Results: LPS stimulation increased the expression of TLR4 mRNA and protein in culture uveal melanocytes. Constitutive secretion of CXCL1/CXCL2 was detected in uveal melanocytes and was significantly increased dose- and time-dependently by LPS stimulation. LPS mainly increased the activated NF-κB and phosphorylated JNK1/2. LPS-induced expression of CXCL1/CXCL2 was blocked by NF-κB and JNK1/2 inhibitors. The severity of LPS-induced uveitis was significantly inhibited by neutralizing antibody to CXCL1/CXCL2Conclusions: This is the first report on the LPS-induced expression of CXCL1 and CXCL2 by uveal melanocytes via the activation of TLR4. These results suggest that uveal melanocytes may play a role in the immune reaction that eliminates the invading pathogens. Conversely, an excessive LPS-induced inflammatory reaction may also lead to the development of inflammatory ocular disorders, such as non-infectious uveitis.

Anti-inflammatory effects of miR-150 are associated with the downregulation of STAT1 in macrophages following lipopolysaccharide treatment

Sepsis is a condition that is associated with high rates of mortality. It is characterized by serious systemic inflammatory responses induced by pathogenic invasion. Although microRNA-150 (miR-150) has been previously reported to be involved in the modulation of sepsis, the underlying molecular mechanism in sepsis remains poorly understood. In the present study, the human monocytic cell line THP-1 was treated with LPS to mimic sepsis in vitro, following which miR-150 and STAT1 expression were measured using reverse transcription-quantitative PCR or western blotting. Secretion of inflammatory cytokines interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNF-α) into the medium were measured by ELISA. The potential relationship between STAT1 and miR-150 was determined using dual-luciferase reporter and RNA immunoprecipitation assays. miR-150 expression was found to be was downregulated by LPS treatment in THP-1 cells in both dose- and time-dependent manners. LPS treatment also induced IL-1β, IL-6 and TNF-α secretion in a manner that could be inhibited by miR-150 overexpression and enhanced by transfection with the miR-150 inhibitor. miR-150 was revealed to directly target STAT1 by negatively regulating its expression. In addition, STAT1 expression was demonstrated to be upregulated by LPS treatment. STAT1 overexpression reversed the inhibitory effects of miR-150 overexpression on IL-1β, IL-6 and TNF-α secretion whilst STAT1 knockdown attenuated IL-1β, IL-6 and TNF-α secretion induced by miR-150 inhibitor transfection. In conclusion, the present study suggested that miR-150 regulates the inflammatory response in macrophages following LPS challenge by regulating the expression of STAT1.

Anti-inflammatory Action of Statins in Cardiovascular Disease: the Role of Inflammasome and Toll-Like Receptor Pathways

Atherosclerosis is one type of cardiovascular disease (CVD) in which activation of the NLRP3 inflammasome and toll-like receptor (TLR) pathways is implicated. One of the most effective treatments for atherosclerosis is the use of statin medications. Recent studies have indicated that statins, in addition to their lipid-lowering effects, exert inhibitory and/or stimulatory effects on the NLRP3 inflammasome and TLRs. Some of the statins lead to activation of the inflammasome and subsequently cause secretion of IL-1β and IL-18. Thus, these actions may further aggravate the disease. On the other hand, some statins cause inhibition of the inflammasome or TLRs and along with lipid-lowering, help to improve the disease by reducing inflammation. In this article, we discuss these contradictory studies and the mechanisms of action of statins on the NLRP3 inflammasome and TLR pathways. The dose-dependent effects of statins on the NLRP3 complex are related to their chemistry, pharmacokinetic properties, and danger signals. Lipophilic statins have more pleiotropic effects on the NLRP3 complex in comparison to hydrophilic statins. Statins can suppress TLR4/MyD88/NF-ĸB signaling and cause an immune response shift to an anti-inflammatory response. Furthermore, statins inhibit the NF-ĸB pathway by decreasing the expression of TLRs 2 and 4. Statins are cost-effective drugs, which should have a continued future in the treatment of atherosclerosis due to both their immune-modulating and lipid-lowering effects.

Link between microbiota and hypertension: Focus on LPS/TLR4 pathway in endothelial dysfunction and vascular inflammation, and therapeutic implication of probiotics

High blood pressure (BP) presents a significant public health challenge. Recent findings suggest that altered microbiota can exert a hypertensive effect on the host. One of the possible mechanisms involved is the chronic translocation of its components, mainly lipopolysaccharides (LPS) into systemic circulation leading to metabolic endotoxemia. In animal models, LPS has been commonly used to induce endothelial dysfunction and vascular inflammation. In human studies, plasma LPS concentration has been positively correlated with hypertension, however, the mechanistic link has not been fully elucidated. It is hypothesised here that the LPS-induced direct alterations to the vascular endothelium and resulting hypertension are possible targets for probiotic intervention. The methodology of this review involved a systematic search of the literature with critical appraisal of papers. Three tranches of search were performed: 1) existing review papers; 2) primary mechanistic animal, in vitro and human studies; and 3) primary intervention studies. A total of 70 peer-reviewed papers were included across the three tranches and critically appraised using SIGN50 for human studies and the ARRIVE guidelines for animal studies. The extracted information was coded into key themes and summarized in a narrative analysis. Results highlight the role of LPS in the activation of endothelial toll-like receptor 4 (TLR4) initiating a cascade of interrelated signalling pathways including: 1) Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase/ Reactive oxygen species (ROS)/ Endothelial nitric oxide synthase (eNOS) pathway leading to endothelial dysfunction; and 2) Mitogen-Activated Protein Kinase (MAPK) and Nuclear factor kappa B (NF-κB) pathways leading to vascular inflammation. Findings from animal intervention studies suggest an improvement in vasorelaxation, vascular inflammation and hypertension following probiotic supplementation, which was mediated by downregulation of LPS-induced pathways. Randomised controlled trials (RCTs) and systematic reviews provided some evidence for the anti-inflammatory effect of probiotics with statistically significant antihypertensive effect in clinical samples and may offer a viable intervention for the management of hypertension.

TLR4 rs1927914 polymorphism contributes to serum TLR4 levels in patients with aortic aneurysm

Toll-like receptor 4 (TLR4) is a crucial regulator of inflammatory reactions and vascular remodeling. Elevated TLR4 expression has been proved to be correlated with an increased risk of aortic aneurysm (AA). This study aimed to explore the influence of TLR4 gene polymorphisms on TLR4 expression levels and its probable functional significance in AA disease. A total of 294 AA patients and 285 controls were enrolled in the study and serum TLR4 levels were detected by ELISA. All the participants were genotyped for two tag-SNPs in TLR4 (rs1927914 in the promoter region and rs11536889 in the 3'-untranslated region) using the KASP method. Relative luciferase activity was measured by the dual-luciferase reporter assay system. The rs1927914 TC, TC/CC genotypes and C allele showed associations with increased serum TLR4 levels in the total population and AA patients (all P<0.05). Further stratified analysis demonstrated that AA subjects with TC or TC/CC genotype of rs1927914 had significantly higher serum levels of TLR4 than those with TT genotype in male, age>60y, hypertension, diabetes, TAA type and size>5.0 cm subgroups (all P<0.05). In binary logistic analysis, rs1927914 TC genotype and dominant model presented significant associations with high TLR4 levels (OR = 1.579 and 1.431, P = 0.020 and 0.049, respectively) after adjusting age, hypertension and diabetes. However, rs11536889 polymorphism had no significant influence on serum TLR4 levels. Regarding rs1927914, luciferase activity of the C allele construct was significantly increased in comparison with the T allele construct (0.589 ± 0.004 vs. 0.340 ± 0.014, P<0.001). Our results provided evidence that rs1927914 polymorphism contributed to serum TLR4 levels, possibly by influencing promoter activity of TLR4, and could be a novel genetic factor in the formation of AA.

Association of Toll-Like Receptor 4 Gene Polymorphisms with Acute Aortic Dissection in a Chinese Han Population

Background

Inflammation may be involved in the pathogenesis of acute aortic dissection (AAD). Toll-like receptor 4 (TLR4) is known to play a critical role in regulating the immune and inflammatory processes. To date, the relationship between genetic variation of TLR4 and AAD is far from clear. The purpose of our study was to illustrate the relevance of TLR4 polymorphisms with the susceptibility to AAD.

Methods

A total of 222 AAD patients and 222 controls were enrolled in this study. Frequency distributions of TLR4 polymorphisms (rs10759932 in the promoter and rs11536889 in the 3′-untranslated region) were determined by the KASP method. Clinical parameters were acquired from subjects' medical records, and serum TLR4 levels were collected from our previously published data.

Results

We found that rs10759932 polymorphism was associated with a reduced risk of AAD in the overall population (CC vs. TT: OR = 0.393, 95%CI = 0.164‐0.939, P = 0.036; recessive model: OR = 0.439, 95%CI = 0.196‐0.984, P = 0.045) and subgroup analyses stratified by sex. The GC genotype and dominant model of rs11536889 conferred a significantly higher risk of AAD compared with GG genotype in female subjects (GC vs. GG: OR = 3.382, 95%CI = 1.051‐10.885, P = 0.041; dominant model: OR = 3.043, 95%CI = 1.041‐8.900, P = 0.042). In addition, a significant interaction between the rs11536889 recessive model and dyslipidemia was observed for an increased risk of AAD (P_interaction = 0.038, OR = 15.229) after the adjustment for potential clinical covariates. We also used the false-positive report probability (FPRP) analysis to validate the significant results. Furthermore, rs11536889 polymorphism could affect the maximal aortic diameters of AAD (P = 0.037), while AAD patients carrying CC genotype of rs10759932 showed lower serum TLR4 levels than TT genotype carriers (P = 0.043).

Conclusions

Our findings provide evidence for the association between TLR4 polymorphisms and AAD susceptibility in a Chinese Han population, which may have some implications for understanding the role of TLR4 in the pathophysiology of AAD.

TRPM7 mediates kidney injury, endothelial hyperpermeability and mortality during endotoxemia

Sepsis is the main cause of mortality in patients admitted to intensive care units. During sepsis, endothelial permeability is severely augmented, contributing to renal dysfunction and patient mortality. Ca²⁺ influx and the subsequent increase in intracellular [Ca²⁺]_i in endothelial cells (ECs) are key steps in the establishment of endothelial hyperpermeability. Transient receptor potential melastatin 7 (TRPM7) ion channels are permeable to Ca²⁺ and are expressed in a broad range of cell types and tissues, including ECs and kidneys. However, the role of TRPM7 on endothelial hyperpermeability during sepsis has remained elusive. Therefore, we investigated the participation of TRPM7 in renal vascular hyperpermeability, renal dysfunction, and enhanced mortality induced by endotoxemia. Our results showed that endotoxin increases endothelial hyperpermeability and Ca²⁺ overload through the TLR4/NOX-2/ROS/NF-κB pathway. Moreover, endotoxin exposure was shown to downregulate the expression of VE-cadherin, compromising monolayer integrity and enhancing vascular hyperpermeability. Notably, endotoxin-induced endothelial hyperpermeability was substantially inhibited by pharmacological inhibition and specific suppression of TRPM7 expression. The endotoxin was shown to upregulate the expression of TRPM7 via the TLR4/NOX-2/ROS/NF-κB pathway and induce a TRPM7-dependent EC Ca²⁺ overload. Remarkably, in vivo experiments performed in endotoxemic animals showed that pharmacological inhibition and specific suppression of TRPM7 expression inhibits renal vascular hyperpermeability, prevents kidney dysfunction, and improves survival in endotoxemic animals. Therefore, our results showed that TRPM7 mediates endotoxemia-induced endothelial hyperpermeability, renal dysfunction, and enhanced mortality, revealing a novel molecular target for treating renal vascular hyperpermeability and kidney dysfunction during endotoxemia, sepsis, and other inflammatory diseases.

DPP-4 inhibition by linagliptin prevents cardiac dysfunction and inflammation by targeting the Nlrp3/ASC inflammasome

We compared the effects of linagliptin (Lina, a DPP4 inhibitor) and GLP-1 receptor activation by exenatide followed by exendin-4 in an infusion pump (EX) on infarct size (IS), post-infarction activation of the inflammasome and remodeling in wild-type (WT) and db/db diabetic mice. Mice underwent 30 min ischemia followed by 24 h reperfusion. IS was assessed by TTC. Additional mice underwent permanent coronary artery occlusion. Echocardiography was performed 2w after infarction. Activation of the inflammasome in the border zone of the infarction was assessed by rt-PCR and ELISA 2w after reperfusion. Further in vitro experiments were done using primary human cardiofibroblasts and cardiomyocytes exposed to simulated ischemia-reoxygenation. Lina and EX limited IS in both the WT and the db/db mice. Lina and EX equally improved ejection fraction in both the WT and the db/db mice. mRNA levels of ASC, NALP3, IL-1β, IL-6, Collagen-1, and Collagen-3 were higher in the db/db mice than in the WT mice. Infarction increased these levels in the WT and db/db mice. Lina more than EX attenuated the increase in ASC, NALP3, IL-1β, IL-6, Collagen-1 and Collagen-3, TNFα and IL-1β, and decreased apoptosis, especially in the db/db mice. In vitro experiments showed that Lina, but not EX, attenuated the increase in TLR4 expression, an effect that was dependent on p38 activation with downstream upregulation of Let-7i and miR-146b levels. Lina and EX had similar effects on IS and post-infarction function, but Lina attenuated the activation of the inflammasome and the upregulation of collagen-1 and collagen-3 more than direct GLP-1 receptor activation. This effect depends on p38 activation with downstream upregulation of miR-146b levels that suppresses TLR4 expression.

Fecal Enterobacteriales enrichment is associated with increased in vivo intestinal permeability in humans

Type 2 diabetes (T2D) has been linked with increased intestinal permeability, but the clinical significance of this phenomenon remains unknown. The objective of this study was to investigate the potential link between glucose control, intestinal permeability, diet and intestinal microbiota in patients with T2D. Thirty‐two males with well‐controlled T2D and 30 age‐matched male controls without diabetes were enrolled in a case–control study. Metabolic parameters, inflammatory markers, endotoxemia, and intestinal microbiota in individuals subdivided into high (HP) and normal (LP) colonic permeability groups, were the main outcomes. In T2D, the HP group had significantly higher fasting glucose (P = 0.034) and plasma nonesterified fatty acid levels (P = 0.049) compared with the LP group. Increased colonic permeability was also linked with altered abundances of selected microbial taxa. The microbiota of both T2D and control HP groups was enriched with Enterobacteriales. In conclusion, high intestinal permeability was associated with poorer fasting glucose control in T2D patients and changes in some microbial taxa in both T2D patients and nondiabetic controls. Therefore, enrichment in the gram‐negative order Enterobacteriales may characterize impaired colonic permeability prior to/independently from a disruption in glucose tolerance.

Macrophage migration inhibitory factor is involved in inflammation response in pathogen challenged Apostichopus japonicus

Macrophage migration inhibitory factor (MIF) is a cytokine and plays critical roles in inflammatory and immune responses in vertebrates. However, its functional role in inflammation has not been well studied in invertebrates. In the present study, we cloned and characterized MIF gene from Apostichopus japonicus by RNA-seq and RACE approaches (designated as AjMIF). A 1047 bp fragment representing the full-length cDNA of AjMIF was obtained, including a 5' UTR of 100 bp, an open reading frame (ORF) of 366 bp encoding a polypeptide of 121 amino acids residues with the molecular weight of 13.43 kDa and theoretical isoelectric point of 5.63 and a 3' UTR of 580 bp. SMART analysis showed that AjMIF has conserved MIF domain (2-117aa) similar to its mammalian counterparts. The amino terminal proline residue (P²) and invariant lysine residue (K³³) which are critical active sites of tautomerase activity in mammalian MIF were also detected. Phylogenic analysis and multiple alignments have shown that AjMIF shared higher degree of structural conservation and sequence identities with other counterparts from invertebrates and vertebrates. For Vibrio splendidus challenged sea cucumber, the peak expression of AjMIF mRNAs in coelomocytes were detected at 6 h (23.5-fold) and remained at high levels until 24 h (4.01-fold), and returned to normal level at 48 h in comparison with that of the control group. Similarly, a significant increase in the relative mRNA levels of AjMIF was also found in 10 μg mL^-1 LPS-exposed primary cultured coelomocytes. Functional analysis indicated that recombinant AjMIF incubation could promote inflammatory response related genes of Ajp105, AjVEGF, AjMMP1 and AjHMGB3 expression by 1.35-fold, 1.36-fold, 1.83-fold and 1.27-fold increase, respectively, which was consistent with the findings in vertebrate MIFs. All these results collectively suggested that AjMIF had a similar function to MIFs in higher animals and might serve as a candidate cytokine in inflammatory regulation in sea cucumber.

TLR4 and MMP2 polymorphisms and their associations with cardiovascular risk factors in susceptibility to aortic aneurysmal diseases

Background: Toll-like receptor 4 (TLR4) and matrix metalloproteinase 2 (MMP2) play important roles in aortic pathophysiology. We aimed to evaluate the contribution of TLR4 and MMP2 polymorphisms individually and complex interactions between gene and risk factors in susceptibility to aortic aneurysm (AA) and its subtypes. Methods: KASP method was adopted to detect TLR4rs11536889, rs1927914 and MMP2rs2285053 polymorphisms in 498 controls and 472 AA patients, including 212 abdominal AA (AAA) and 216 thoracic AA (TAA). Results: In the overall analysis, MMP2rs2285053 TC genotype was correlated with TAA risk (P = 0.047, OR = 1.487). Stratified analysis revealed an increased AA risk in males with TLR4rs1927914 TC genotype, while MMP2rs2285053 TC conferred an elevated AA risk in the subjects ≤60 years, and its TC genotype and dominant model were associated with TAA in the subjects ≤60 year. The interaction between TLR4rs1927914 and MMP2rs2285053 was associated with AAA risk (P _interaction = 0.028, OR = 2.913). Furthermore, significant interaction between TLR4rs11536889 and dyslipidemia was observed for TAA risk, while TLR4rs1927914 could interact with hypertension and diabetes to increase the risk of AA or its subtypes. Two-way interaction effect of TLR4rs1927914 and MMP2rs2285053 was enhanced by diabetes or dyslipidemia. Conclusion: TLR4 and MMP2 polymorphisms and their complex interactions with cardiovascular risk factors contributed to aortic aneurysmal diseases.

Serum levels of matrix metalloproteinase 9 and toll-like receptor 4 in acute aortic dissection: a case-control study

Background

Matrix metalloproteinase 9 (MMP9) and Toll-like receptor 4 (TLR4) play important roles in aortic pathophysiology. However, there is lacking research on serum TLR4 levels in acute aortic dissection (AAD) patients, and the performance of serum MMP9 and TLR4 for the diagnosis of AAD is still unknown. This study aimed to evaluate the serum levels of MMP9 and TLR4 in AAD patients, identify their associations with circulating C-reactive protein (CRP) and D-dimer, which are well-known classical biomarkers of AAD, and further explore the potential diagnostic role of MMP9 and TLR4 in AAD.

Methods

Serum levels of MMP9 and TLR4 were measured by enzyme-linked immunosorbent assay (ELISA) in 88 AAD patients and 88 controls. The clinical test related information was collected from patients’ electronic medical records.

Results

Serum MMP9 and TLR4 levels were significantly higher in AAD patients than those in healthy controls in the general and stratified comparisons. Either serum MMP9 or TLR4 was independently associated with the risk of AAD (all p < 0.001). There was a positive significant association between serum MMP9 and TLR4 (r = 0.518, p < 0.001). Both MMP9 and TLR4 levels were statistically correlated with circulating CRP, but not D-dimer. Based on receiver-operating characteristic (ROC) analysis, the area under the curves (AUCs) of MMP9 and TLR4 alone for the diagnosis of AAD were 0.810 and 0.799 with optimal cut-off points of 379.47 ng/ml and 7.83 ng/ml, respectively. Moreover, a combination of serum MMP9 and TLR4 increased the AUC to 0.89 with a sensitivity of 60.2% and specificity of 94.3%.

Conclusions

Serum MMP9 and TLR4 could be potential biomarkers for identifying AAD, while the combined diagnostic value was higher in safely ruling out AAD.

Effect of statins on toll-like receptors: a new insight to pleiotropic effects

The toll-like receptors (TLRs) are a class of transmembrane-spanning receptors that are sentinels of both innate and adaptive immunity. Statins (3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors) are the most commonly prescribed therapeutic agents for treating hypercholesterolemia globally. However, statin therapy appears to have pleiotropic effects including attenuation of chronic low-grade inflammation and modulation of TLR activity. Statins through abolition of TLR4 expression and regulation of the TLR4/Myd88/NF-κB signaling pathway may slow the progression of atherosclerosis and other inflammatory diseases. In this review, we have focused on the impact and mechanism of action of statins on cardiovascular and non-cardiovascular diseases.

Water/ethanol extract of Cucumis sativus L. fruit attenuates lipopolysaccharide-induced inflammatory response in endothelial cells

Background

It is widely accepted the key role of endothelium in the onset of many chronic and acute vascular and cardiovascular diseases.

In the last decade, traditional compounds utilized in “folk medicine” were considered with increasing interest to discover new bioactive molecules potentially effective in a wide range of diseases including cardiovascular ones. Since ancient times different parts of the Cucumis sativus L. plant were utilized in Ayurvedic medicine, among these, fruits were traditionally used to alleviate skin problem such as sunburn irritation and inflammation. The main purpose of the present research was, in a well-defined in vitro model of endothelial cells, to investigate whether a water/ethanol extract of Cucumis sativus L. (CSE) fruit can attenuate the damaging effect of pro-inflammatory lipopolysaccharide (LPS).

Methods

Cell viability, gene expression of endothelial cell markers, cytokines secretion and in vitro angiogenesis assay were performed on porcine Aortic Endothelial Cells exposed to increasing doses (0.02; 02; 2 mg/ml) of CSE in the presence of pro-inflammatory lipopolysaccharide (LPS 10 μg/ml).

Results

CSE reduced LPS-induced cytotoxicity and decreased the cellular detachment, restoring the expression of tight junction ZO-1. The increase of TLR4 expression induced by LPS was counterbalanced by the presence of CSE, while the protective gene Hemeoxygenase (HO)-1 was increased. Cucumis sativus L. inhibited the early robust secretion of inflammatory IL-8 and GM-CSFs, furthermore inhibition of inflammatory IL-6 and IL-1α occurred late at 7 and 24 h respectively. On the contrary, the secretion of anti-inflammatory IL-10, together with IL-18 and IFN-γ was increased. Moreover, the in vitro angiogenesis induced by inflammatory LPS was prevented by the presence of Cucunis sativus L. extract, at any doses tested.

Conclusions

Our results have clearly demonstrated that Cucumis sativus L. extract has attenuated lipopolysaccharide-induced inflammatory response in endothelial cells.

Translating the effects of statins: from redox regulation to suppression of vascular wall inflammation

Vascular oxidative stress is a key feature of atherogenesis, and targeting vascular redox signalling is a rational therapeutic goal in vascular disease pathogenesis. 3-hydroxy-3-methyl-glutaryl-CoA reductase inhibitors or statins are potent lipid-lowering drugs that improve cardiovascular outcomes. It is now widely accepted that cardiovascular disease prevention by statins is dependent not only on their lipid lowering effects, but also on their beneficial effects on vascular redox signalling. Cell culture and animal models have provided important findings on the effects of statins on vascular redox and nitric oxide bioavailability. Recent evidence from studies on human vessels has further enhanced our understanding of the "pleiotropic" effects of statins on vascular wall. Reversal of endothelial dysfunction in human vessels by statins is dependent on the mevalonate pathway and Rac1 inhibition. These critical steps are responsible for reducing NADPH-oxidase activity and improving tetrahydrobiopterin bioavailability and nitric oxide synthase (NOS) coupling in human vessels. However, mevalonate pathway inhibition has been also held responsible for some of the side effects observed after statin treatment. In this review we summarise the existing knowledge on the effects of statins on vascular biology by discussing key findings from basic science as well as recent evidence from translational studies in humans. Finally, we discuss emerging aspects of statin pleiotropy, such as their effects on adipose tissue biology and adipokine synthesis that may light additional mechanistic links between statin treatment and improvement of clinical outcome in primary and secondary prevention.

Linezolid and atorvastatin impact on pneumonia caused by Staphyloccocus aureus in rabbits with or without mechanical ventilation

Pneumonia may involve methicillin-resistant Staphylococcus aureus (MRSA), with elevated rates of antibiotics failure. The present study aimed to assess the effect of statins given prior to pneumonia development. Spontaneously breathing (SB) or mechanically ventilated (MV) rabbits with pneumonia received atorvastatin alone, linezolid (LNZ) alone, or a combination of both (n = 5 in each group). Spontaneously breathing and MV untreated infected animals (n = 11 in each group), as well as uninfected animals (n = 5 in each group) were used as controls. Microbiological features and inflammation were evaluated. Data are presented as medians (interquartile range). Linezolid alone tended to reduce pulmonary MRSA load in both SB and MV rabbits, but failed to prevent bacteremia (59%) in the latter. Linezolid alone dampened TNF-α lung production in both SB and MV rabbits (e.g., 2226 [789] vs. 11478 [10251] pg/g; p = 0.022). Statins alone did the same in both SB and MV animals (e.g., 2040 [133]; p = 0.016), and dampened systemic inflammation in the latter, possibly through TLR2 down-regulation within the lung. However, the combination of LNZ and statin led to an increased rate of bacteremia in MV animals up to 75%. Statins provide an anti-inflammatory effect in rabbits with MRSA pneumonia, especially in MV ones. However, dampening the systemic inflammatory response with statins could impede blood defenses against MRSA.

Treating the host response to emerging virus diseases: lessons learned from sepsis, pneumonia, influenza and Ebola

There is an ongoing threat of epidemic or pandemic diseases that could be caused by influenza, Ebola or other emerging viruses. It will be difficult and costly to develop new drugs that target each of these viruses. Statins and angiotensin receptor blockers (ARBs) have been effective in treating patients with sepsis, pneumonia and influenza, and a statin/ARB combination appeared to dramatically reduce mortality during the recent Ebola outbreak. These drugs target (among other things) the endothelial dysfunction found in all of these diseases. Most scientists work on new drugs that target viruses, and few accept the idea of treating the host response with generic drugs. A great deal of research will be needed to show conclusively that these drugs work, and this will require the support of public agencies and foundations. Investigators in developing countries should take an active role in this research. If the next Public Health Emergency of International Concern is caused by an emerging virus, a "top down" approach to developing specific new drug treatments is unlikely to be effective. However, a "bottom up" approach to treatment that targets the host response to these viruses by using widely available and inexpensive generic drugs could reduce mortality in any country with a basic health care system. In doing so, it would make an immeasurable contribution to global equity and global security.

Involvement of peroxisome proliferator activated receptor-γ in the anti-inflammatory effects of atorvastatin in oxygen-glucose deprivation/reperfusion-stimulated RAW264.7 murine macrophages

Ischemia-reperfusion (I/R) injury is important in the pathogenesis and/or progression of various diseases, including stroke, cardiovascular disease and acute renal injury. Increasing evidence indicates that atorvastatin exerts protective effects in I/R injury-associated diseases; however, the underlying mechanisms remain to be fully elucidated. In the present study, oxygen-glucose deprivation (OGD)/reperfusion-stimulated. RAW264.7 murine macrophages served as a model of I/R injury. The knockdown of peroxisome proliferator activated receptor-γ (PPARγ) expression in these cells increased OGD/reperfusion-induced expression of inducible nitric oxide synthase (iNOS), tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ), and enhanced OGD/reperfusion-induced downregulation of the expression of cluster of differentiation (CD) 206, at the mRNA and protein levels. Conversely, overexpression of PPARγ significantly attenuated OGD/reperfusion-induced alterations in the expression of iNOS, TNF-α, IFN-γ and CD206 at the mRNA and protein levels. Notably, atorvastatin inhibited OGD/reperfusion-induced iNOS expression and reversed OGD/reperfusion-induced downregulation of the expression of CD206 and PPARγ at the mRNA and protein levels. The results of the present study indicate that atorvastatin exhibits significant anti-inflammatory effects in OGD/reperfusion-stimulated RAW264.7 cells, possibly via PPARγ regulation. The findings of the present study may reveal a novel mechanism underlying the protective effects of atorvastatin in I/R injury-associated diseases.

S100A8/A9: From basic science to clinical application

Neutrophils and monocytes belong to the first line of immune defence cells and are recruited to sites of inflammation during infection or sterile injury. Both cells contain huge amounts of the heterodimeric protein S100A8/A9 in their cytoplasm. S100A8/A9 belongs to the Ca²⁺ binding S100 protein family and has recently gained a lot of interest as a critical alarmin modulating the inflammatory response after its release (extracellular S100A8/A9) from neutrophils and monocytes. Extracellular S100A8/A9 interacts with the pattern recognition receptors Toll-like receptor 4 (TLR4) and Receptor for Advanced Glycation Endproducts (RAGE) promoting cell activation and recruitment. Besides its biological function, S100A8/A9 (also known as myeloid related protein 8/14, MRP8/14) was identified as interesting biomarker to monitor disease activity in chronic inflammatory disorders including inflammatory bowel disease and rheumatoid arthritis. Furthermore, S100A8/A9 has been tested successfully in pre-clinical imaging studies to localize sites of infection or sterile injury. Finally, recent evidence using small molecule inhibitors for S100A8/A9 also suggests that blocking S100A8/A9 activity exerts beneficial effects on disease activity in animal models of autoimmune diseases including multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis and inflammatory bowel disease. This review will provide a comprehensive and detailed overview into the structure and biological function of S100A8/A9 and also will give an outlook in terms of diagnostic and therapeutic applications targeting S100A8/A9.

Statin pretreatment inhibits the lipopolysaccharide-induced epithelial-mesenchymal transition via the downregulation of toll-like receptor 4 and nuclear factor-κB in human biliary epithelial cells

BACKGROUND AND AIM

Epithelial-mesenchymal transition (EMT) of biliary epithelial cells (BECs) plays an important role in biliary fibrosis. This study investigated the effects of simvastatin on the lipopolysaccharide (LPS)-induced EMT and related signal pathways in BECs.

METHODS

Biliary epithelial cells were exposed to LPS (2 µg/mL) or transforming growth factor β1 (TGF-β1) (5 ng/mL) for 5 days. The EMT was assessed by a gain of mesenchymal cell markers (vimentin, N-cadherin, slug, and Twist-1) and a loss of epithelial cell markers (E-cadherin). The effects of simvastatin on the EMT induced by LPS or TGF-β1 were determined by the changes in the levels of EMT markers and TLR4 and in the c-Jun N-terminal kinase (JNK), p38, and nuclear factor-κB (NF-κB) signaling pathways.

RESULTS

Compared with the BECs treated with LPS alone, co-treatment with simvastatin and LPS induced an increase in the expression of E-cadherin and decreases in the expression levels of mesenchymal cell markers. The LPS-induced TLR4 expression level was slightly decreased by co-treatment with simvastatin. LPS-induced BEC growth was markedly inhibited by co-treatment with simvastatin. Furthermore, pretreatment with simvastatin inhibited the LPS-induced EMT in BECs by downregulating NF-κB and JNK phosphorylation. The suppressive effects of simvastatin pretreatment on the induction of the EMT by TGF-β1 were also demonstrated in H69 cells.

CONCLUSIONS

Our results demonstrate that LPS or TGF-β1 promote the EMT in BECs that that pretreatment with simvastatin inhibited the induced EMT by downregulating toll-like receptor 4 and NF-κB phosphorylation. This finding suggests that simvastatin can be considered a new agent for preventing biliary fibrosis associated with the EMT of BECs.

Macrophage migration inhibitory factor promotes breast cancer metastasis via activation of HMGB1/TLR4/NF kappa B axis

Macrophage migration inhibitory factor (MIF) is up-regulated in diverse solid tumors and acts as the critical link between immune response and tumorigenesis. In this study, we demonstrated that MIF overexpression promoted migration of breast cancer cells by elevating TLR4 expression. Further investigation evidenced that MIF induced ROS generation. MIF-induced ROS led to ERK phosphorylation, which facilitated HMGB1 release from the nucleus to the cytoplasm. MIF overexpression also induced caveolin-1 phosphorylation. Caveolin-1 phosphorylation contributed to HMGB1 secretion from the cytoplasm to the extracellular matrix. The extracellular HMGB1 activated TLR4 signaling including NF-κB phosphorylation, which was responsible for the transcription of Snail and Twist as well as MMP2 activation. Furthermore, MIF-induced caveolin-1-dependent HMGB1 secretion might control the recruitment of CD11b+ immune cells. Our data suggested that MIF affected the intrinsic properties of tumors and the host immune response in tumor microenvironment by regulating the TLR4/HMGB1 axis, leading to metastasis of breast cancer.

Hypochlorite-Modified Albumin Upregulates ICAM-1 Expression via a MAPK-NF-κB Signaling Cascade: Protective Effects of Apocynin

Hypochlorite-modified albumin (HOCl-alb) has been linked to endothelial dysfunction, which plays an important role in the development of hypertension, diabetes, and chronic kidney disease. However, whether HOCl-alb induces endothelial dysfunction via vascular inflammation and whether a signaling pathway is involved are unknown and have not been investigated. HOCl-alb was found to upregulate ICAM-1 expression in human umbilical vein endothelial cells (HUVECs) in a time- and dose-dependent manner. HOCl-alb time-dependently phosphorylated ERK1/2 and p38(MAPK). HOCl-alb also activated NF-κB. ICAM-1 expression was dose-dependently inhibited by U0126 (a specific inhibitor of MEK1/2, a signal upstream from ERK1/2), SB203580 (a specific inhibitor of p38(MAPK)), and SN50 (a specific inhibitor of NF-κB). U0126 and SB203580 both counteracted the activation of NF-κB, whereas the phosphorylation of ERK1/2 and p38(MAPK) was not blocked by SN50. ERK1/2 phosphorylation was blocked by U0126 but not by SB203580, and p38(MAPK) activity was reduced by SB203580 but not by U0126. Apocynin, a specific NADPH oxidase (NOX) inhibitor, inhibited ICAM-1 expression and the activity of ERK1/2, p38(MAPK), and NF-κB. These results indicate that HOCl-alb-induced ICAM-1 expression is caused by the activation of a redox-sensitive intracellular signal cascade involving ERK1/2 and p38(MAPK), culminating in the activation of NF-κB and involving NOXs among the upstream signals.

Toll-like Receptors in the Vascular System: Sensing the Dangers Within

Toll-like receptors (TLRs) are components of the innate immune system that respond to exogenous infectious ligands (pathogen-associated molecular patterns, PAMPs) and endogenous molecules that are released during host tissue injury/death (damage-associated molecular patterns, DAMPs). Interaction of TLRs with their ligands leads to activation of downstream signaling pathways that induce an immune response by producing inflammatory cytokines, type I interferons (IFN), and other inflammatory mediators. TLR activation affects vascular function and remodeling, and these molecular events prime antigen-specific adaptive immune responses. Despite the presence of TLRs in vascular cells, the exact mechanisms whereby TLR signaling affects the function of vascular tissues are largely unknown. Cardiovascular diseases are considered chronic inflammatory conditions, and accumulating data show that TLRs and the innate immune system play a determinant role in the initiation and development of cardiovascular diseases. This evidence unfolds a possibility that targeting TLRs and the innate immune system may be a novel therapeutic goal for these conditions. TLR inhibitors and agonists are already in clinical trials for inflammatory conditions such as asthma, cancer, and autoimmune diseases, but their study in the context of cardiovascular diseases is in its infancy. In this article, we review the current knowledge of TLR signaling in the cardiovascular system with an emphasis on atherosclerosis, hypertension, and cerebrovascular injury. Furthermore, we address the therapeutic potential of TLR as pharmacological targets in cardiovascular disease and consider intriguing research questions for future study.

Gene silencing of TACE enhances plaque stability and improves vascular remodeling in a rabbit model of atherosclerosis

We aimed to test the hypothesis that gene silencing of tumor necrosis factor alpha converting enzyme (TACE) may attenuate lesion inflammation and positive vascular remodeling and enhance plaque stability in a rabbit model of atherosclerosis. Lentivirus-mediated TACE shRNA was injected into the abdominal aortic plaques of rabbits which effectively down-regulated TACE expression and activities from week 8 to week 16. TACE gene silencing reduced remodeling index and plaque burden, and diminished the content of macrophages and lipids while increased that of smooth muscle cells and collagen in the aortic plaques. In addition, TACE gene silencing attenuated the local expression of P65, iNOS, ICAM-1, VEGF and Flt-1 and activities of MMP9 and MMP2 while increased the local expression of TGF-β1 together with reduced number of neovessels in the aorta. TACE shRNA treatment resulted in down-regulated expression of TACE in macrophages and blunted ERK-P38 phosphorylation and tube formation of co-cultured mouse vascular smooth muscle cells or human umbilical vein endothelial cells. In conclusion, gene silencing of TACE enhanced plaque stability and improved vascular positive remodeling. The mechanisms may involve attenuated local inflammation, neovascularization and MMP activation, as well as enhanced collagen production probably via down-regulated ERK-NF-κB and up-regulated TGF-β1 signaling pathways.

Efficacy of atorvastatin on hippocampal neuronal damage caused by chronic intermittent hypoxia: Involving TLR4 and its downstream signaling pathway

Hippocampal neuronal damage is critical for the initiation and progression of neurocognitive impairment accompanied obstructive sleep apnea syndrome (OSAS). Toll-like receptor 4 (TLR4) plays an important role in the development of several hippocampus-related neural disorders. Atorvastatin was reported beneficially regulates TLR4. Here, we examined the effects of atorvastatin on hippocampal injury caused by chronic intermittent hypoxia (CIH), the most characteristic pathophysiological change of OSAS. Mice were exposed to intermittent hypoxia with or without atorvastatin for 4 weeks. Cell damage, the expressions of TLR4 and its two downstream factors myeloid differentiation factor 88 (MYD88) and TIR-domain-containing adapter-inducing interferon-β (TRIF), inflammatory agents (tumor necrosis factor α and interleukin 1β), and the oxidative stress (superoxide dismutase and malondialdehyde) were determined. Atorvastatin decreased the neural injury and the elevation of TLR4, MyD88, TRIF, pro-inflammatory cytokines and oxidative stress caused by CIH. Our study suggests that atorvastatin may attenuate CIH induced hippocampal neuronal damage partially via TLR4 and its downstream signaling pathway.

Monophosphoryl lipid A inhibits the cytokine response of endothelial cells challenged with LPS

Monophosphoryl lipid A (MPLA) is a TLR4 agonist that is used as an immunomodulator in human vaccines; additionally, it has been shown to be protective in models of sepsis. As endothelial cells regulate inflammation, we hypothesized that MPLA would decrease activation of human umbilical vein endothelial cells (HUVECs) to LPS. We studied HUVECs challenged with LPS (100 ng/ml), MPLA (0.001-100 µg/ml) or a combination. Secretion of IL-6, RANTES (CCL5) and IP-10 (CXCL10) were assessed by ELISA. Activation of MAPK phosphorylation and cytokine transcription were assessed by Western blot analysis and PCR, respectively. MPLA alone was a weak stimulator of myeloid differentiation primary response protein 88-dependent IL-6 and did not induce TIR-domain-containing adapter-inducing IFN-β (TRIF)-dependent chemokine responses. MPLA significantly reduced LPS-mediated IL-6 production. This inhibitory effect was also conferred for the TRIF-dependent chemokines RANTES and IP-10. Inhibition of LPS-mediated activation by MPLA was associated with reduced p38 phosphorylation and mRNAs encoding inflammatory cytokines. MPLA inhibition of LPS signaling appeared to be at the level of the TLR4 receptor, acting as a receptor antagonist with weak agonistic properties. This study provides evidence of a novel mechanism for the inhibitory effect of MPLA on LPS-induced endothelial activation.

Simvastatin attenuates angiotensin II‑induced inflammation and oxidative stress in human mesangial cells

Chronic kidney disease (CKD) is an intractable disease in which inflammation and oxidative stress are important. In the present study, the effect of simvastatin on inflammation and oxidative stress induced by angiotensin II (Ang II) in human mesangial cells (HMCs) and its corresponding mechanism was examined. In the in vitro experiment, HMCs were pretreated either without additives (control group) or with simvastatin at different concentrations (0, 0.1, 1 or 10 µM) for 1 h and were then stimulated by Ang II (1 µM) for 24 h. Following stimulation, the cells were collected for analysis using quantitative polymerase chain reaction, western blotting and dihydroethidium staining. The supernatant of the cells was collected and analyzed using an enzyme‑linked immunosorbent assay. The results demonstrated that simvastatin suppressed the increased mRNA expression of monocyte chemoattractant protein‑1, tumor necrosis factor‑α, interleukin (IL)‑1β and IL‑6 and the content of reactive oxygen species induced by Ang II in a dose‑dependent manner. In addition, simvastatin decreased the protein expression of cyclooxygenase‑2 (COX‑2), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and protein kinase C (PKC) as well as the content of prostaglandin E2 and the phosphorylation level of nuclear factor‑κB (NF‑κB) p65 in a dose‑dependent manner. Furthermore, simvastatin significantly increased the protein expression of peroxisome proliferator‑activated receptor γ (PPARγ). Therefore, simvastatin suppressed inflammation and oxidative stress in Ang II‑stimulated HMCs via COX‑2, PPARγ, NF‑κB, NADPH oxidase and PKCs, thereby exerting a protective effect on CKD.

Toll-like receptors: Role in inflammation and therapeutic potential

Inflammation is an essential process in response to injury and infection. However, under certain circumstances dis-regulation of this process can lead to pathologies such as rheumatoid arthritis, atherosclerosis, lupus, and is a contributory factor in the progression of many cancers. The Toll-like family of receptors (TLRs) has major roles in the initiation of the inflammatory response and as such has attracted much focus for their potential as therapeutic targets. Here we review the role of TLRs in the inflammatory response and associated disease and examine how this important family of molecules might be targeted for therapeutic benefit.

TNF-α upregulates Fgl2 expression in rat myocardial ischemia/reperfusion injury

OBJECTIVE

Proinflammatory cytokine TNF-α during MI/R injury has been studied extensively. However, how TNF-α induces microvascular dysfunction in MI/R is still unclear. This study investigates whether TNF-α regulates fibrinogen-like protein 2 (fgl2) expression, a procoagulant resulting in the formation of fibrin-rich microthrombus in MI/R injury.

METHODS AND RESULTS

Microthrombosis, TNF-α and fgl2 expression were assessed in rats with MI/R injury. The effect of TNF-α on fgl2 expression and fgl2 prothrombinase activity was investigated in CMECs, then CMECs were pretreated with selective inhibitors of NF-κB and p38 MAPK pathways. TNF-α and fgl2 expression were both upregulated in MI/R group. When neutralization of TNF-α, fgl2 expression was decreased in vivo. Fgl2 expression was upregulated in CMECs exposed to TNF-α. Accordingly, the ability of thrombin generation was increased in CMECs. Besides, TNF-α-induced fgl2 expression in the cells was suppressed by NF-κB inhibitor PDTC and/or p38 MAPK inhibitor SB203580.

CONCLUSION

TNF-α upregulates fgl2 expression via activation of NF-kB and p38 MAPK in CMECs. TNF-α-induced flg2 in CMECs mediates the formation of fibrin-rich microthrombus, which may be one of the mechanisms of microvascular dysfunction or obstruction due to MI/R injury.

Functional characterization of S100A8 and S100A9 in altering monolayer permeability of human umbilical endothelial cells

S100A8, S100A9 and S100A8/A9 complexes have been known as important endogenous damage-associated molecular pattern (DAMP) proteins. But the pathophysiological roles of S100A8, S100A9 and S100A8/A9 in cardiovascular diseases are incompletely explained. In this present study, the effects of homo S100A8, S100A9 and their hetero-complex S100A8/A9 on endothelial barrier function were tested respectively in cultured human umbilical venous endothelial cells (HUVECs). The involvement of TLR4 and RAGE were observed by using inhibitor of TLR4 and blocking antibody of RAGE. The clarification of different MAPK subtypes in S100A8/A9-induced endothelial response was implemented by using specific inhibitors. The calcium-dependency was detected in the absence of Ca²⁺ or in the presence of gradient-dose Ca²⁺. The results showed that S100A8, S100A9 and S100A8/A9 could induce F-actin and ZO-1 disorganization in HUVECs and evoked the increases of HUVEC monolayer permeability in a dose- and time-dependent manner. The effects of S100A8, S100A9 and S100A8/A9 on endothelial barrier function depended on the activation of p38 and ERK1/2 signal pathways through receptors TLR4 and RAGE. Most importantly, we revealed the preference of S100A8 on TLR4 and S100A9 on RAGE in HUVECs. The results also showed the calcium dependency in S100A8- and S100A9-evoked endothelial response, indicating that calcium dependency on formation of S100A8 or A9 dimmers might be the prerequisite for this endothelial functional alteration.

Atorvastatin attenuates myocardial remodeling induced by chronic intermittent hypoxia in rats: partly involvement of TLR-4/MYD88 pathway

Inflammatory processes and oxidative stress are known to play a key role in the development of cardiovascular complications such as cardiac hypertrophy induced by chronic intermittent hypoxia (CIH), the most characteristic pathophysiological change of obstructive sleep apnea syndrome (OSAS). Current evidence suggests that competitive inhibitors of 3-hydroxy-3-methylglutaryl-CoA coenzyme A reductase, such as atorvastatin, not only reduce blood lipids but also have anti-inflammatory and inhibit oxidative stress benefits. This study examined the protective role of atorvastatin in CIH-induced cardiac hypertrophy. Adult male wistar rats were subjected to 8h of intermittent hypoxia/day, with/without atorvastatin for 6 weeks. Ventricular remodeling, toll-like receptor 4 (TLR-4), myeloid differentiation primary response protein 88 (MYD88), inflammatory agents and radical oxygen species were determined. As a result, we found that treatment with atorvastatin markedly inhibited the mRNA and protein expressions of TLR4, MYD88 and the downstream inflammatory agents and radical oxygen species. Administration of atorvastatin following CIH significantly ameliorated the myocardial injury, such as cardiac hypertrophy. In conclusion, Pre-CIH atorvastatin administration may attenuate TLR-4/MYD88 mediated inflammatory processes and oxidative stress in the injured rat myocardium, and this may be one mechanism by which atorvastatin ameliorated myocardial injury following CIH.

Statins in heart failure--With preserved and reduced ejection fraction. An update

HMG-CoA reductase inhibitors or statins beyond their lipid lowering properties and mevalonate inhibition exert also their actions through a multiplicity of mechanisms. In heart failure (HF) the inhibition of isoprenoid intermediates and small GTPases, which control cellular function such as cell shape, secretion and proliferation, is of clinical significance. Statins share also the peroxisome proliferator-activated receptor pathway and inactivate extracellular-signal-regulated kinase phosphorylation suppressing inflammatory cascade. By down-regulating Rho/Rho kinase signaling pathways, statins increase the stability of eNOS mRNA and induce activation of eNOS through phosphatidylinositol 3-kinase/Akt/eNOS pathway restoring endothelial function. Statins change also myocardial action potential plateau by modulation of Kv1.5 and Kv4.3 channel activity and inhibit sympathetic nerve activity suppressing arrhythmogenesis. Less documented evidence proposes also that statins have anti-hypertrophic effects - through p21ras/mitogen activated protein kinase pathway - which modulate synthesis of matrix metalloproteinases and procollagen 1 expression affecting interstitial fibrosis and diastolic dysfunction. Clinical studies have partly confirmed the experimental findings and despite current guidelines new evidence supports the notion that statins can be beneficial in some cases of HF. In subjects with diastolic HF, moderately impaired systolic function, low b-type natriuretic peptide levels, exacerbated inflammatory response and mild interstitial fibrosis evidence supports that statins can favorably affect the outcome. Under the lights of this evidence in this review article we discuss the current knowledge on the mechanisms of statins' actions and we link current experimental and clinical data to further understand the possible impact of statins' treatment on HF syndrome.

Overview of community-acquired pneumonia and the role of inflammatory mechanisms in the immunopathogenesis of severe pneumococcal disease

Community-acquired pneumonia (CAP) remains a leading cause of morbidity and mortality among the infectious diseases. Despite the implementation of national pneumococcal polyvalent vaccine-based immunisation strategies targeted at high-risk groups, Streptococcus pneumoniae (the pneumococcus) remains the most common cause of CAP. Notwithstanding the HIV pandemic, major challenges confronting the control of CAP include the range of bacterial and viral pathogens causing this condition, the ever-increasing problem of antibiotic resistance worldwide, and increased vulnerability associated with steadily aging populations in developed countries. These and other risk factors, as well as diagnostic strategies, are covered in the first section of this review. Thereafter, the review is focused on the pneumococcus, specifically the major virulence factors of this microbial pathogen and their role in triggering overexuberant inflammatory responses which contribute to the immunopathogenesis of invasive disease. The final section of the review is devoted to a consideration of pharmacological, anti-inflammatory strategies with adjunctive potential in the antimicrobial chemotherapy of CAP. This is focused on macrolides, corticosteroids, and statins with respect to their modes of anti-inflammatory action, current status, and limitations.

Propofol inhibits hypoxia/reoxygenation-induced human gastric epithelial cell injury by suppressing the Toll-like receptor 4 pathway

This study aimed to investigate the role of the Toll-like receptor 4 (TLR4) pathway in normal human gastric epithelial (GES-1) cells under hypoxia/reoxygenation (H/R) in vitro, and the effect of propofol on injured GES-1 cells as well as its possible mechanism. Before H/R induction, GES-1 cells were preconditioned with fat emulsion, propofol, or epigallocatechin gallate. Then cell viability, cell apoptosis, and related molecules in the cells were analyzed under experimental conditions. We found that propofol 50 μmol/L markedly inhibited the H/R injury under hypoxia 1.5 h/reoxygenation 2 hours by promoting GES-1 cell viability and decreasing cell apoptosis. The TLR4 signal may be involved in the protective effect of propofol against H/R injury. The malondialdehyde contents and superoxide dismutase activities were recovered under propofol preconditioning. In summary, propofol preconditioning may exert a protective effect on H/R injury in GES-1 cells and the mechanism may be via inhibition of the activated TLR4 signal under H/R conditions.

Looped host defense peptide CLP-19 binds to microtubules and inhibits surface expression of TLR4 on mouse macrophages

The looped host defense peptide CLP-19 is derived from a highly functional core region of the Limulus anti-LPS factor and exerts robust anti-LPS activity by directly interacting with LPS in the extracellular space. We previously showed that prophylactic administration of CLP-19 even 20 h prior to LPS challenge might significantly increase the survival rate in a lethal endotoxin shock mouse model. Such an effect may be associated with immune regulation of CLP-19. To investigate the underlying mechanisms, peptide affinity chromatography, immunofluorescence, and Western blotting procedures were used to identify α- and β-tubulin as direct and specific binding partners of CLP-19 in the mouse macrophage cell line RAW 264.7. Bioinformatic analysis using the AutoDock Vina molecular docking and PyMOL molecular graphics system predicted that CLP-19 would bind to the functional residues of both α- and β-tubulin and would be located within the groove of microtubules. Tubulin polymerization assay revealed that CLP-19 might induce polymerization of microtubules and prevent depolymerization. The immunoregulatory effect of CLP-19 involving microtubules was investigated by flow cytometry, immunofluorescence, and Western blotting, which showed that CLP-19 prophylactic treatment of RAW 264.7 cells significantly inhibited LPS-induced surface expression of TLR4. Taken together, these results suggest that CLP-19 binding to microtubules disrupts the dynamic equilibrium of microtubules, reducing the efficacy of microtubule-dependent vesicular transport that would otherwise translocate TLR4 from the endoplasmic reticulum to the cell surface.

Effects of simvastatin administration on rodents with lipopolysaccharide-induced liver microvascular dysfunction

Endothelial dysfunction drives vascular derangement and organ failure associated with sepsis. However, the consequences of sepsis on liver sinusoidal endothelial function are largely unknown. Statins might improve microvascular dysfunction in sepsis. The present study explores liver vascular abnormalities and the effects of statins in a rat model of endotoxemia. For this purpose, lipopolysaccharide (LPS) or saline was given to: (1) rats treated with placebo; (2) rats treated with simvastatin (25 mg/kg, orally), given at 3 and 23 hours after LPS/saline challenge; (3) rats treated with simvastatin (25 mg/kg/24 h, orally) from 3 days before LPS/saline injection. Livers were isolated and perfused and sinusoidal endothelial function was explored by testing the vasodilation of the liver circulation to increasing concentrations of acetylcholine. The phosphorylated endothelial nitric oxide synthase (PeNOS)/endothelial nitric oxide synthase (eNOS) ratio was measured as a marker of eNOS activation. LPS administration induced an increase in baseline portal perfusion pressure and a decrease in vasodilation to acetylcholine (sinusoidal endothelial dysfunction). This was associated with reduced eNOS phosphorylation and liver inflammation. Simvastatin after LPS challenge did not prevent the increase in baseline portal perfusion pressure, but attenuated the development of sinusoidal endothelial dysfunction. Treatment with simvastatin from 3 days before LPS prevented the increase in baseline perfusion pressure and totally normalized the vasodilating response of the liver vasculature to acetylcholine and reduced liver inflammation. Both protocols of treatment restored a physiologic PeNOS/eNOS ratio.

CONCLUSION

LPS administration induces intrahepatic endothelial dysfunction that might be prevented by simvastatin, suggesting that statins might have potential for liver protection during endotoxemia.

Regulation of TLR4, p38 MAPkinase, IκB and miRNAs by inactivated strains of lactobacilli in human dendritic cells

Strain specific properties of probiotics in providing supportive health effects in the immune system and the gastrointestinal tract have been widely investigated in vivo and in vitro. However, the underlying responsible mechanism is poorly described. By unravelling the probiotic-induced responses in a complex network of interacting signalling pathways, we investigated the effect of heat-inactivated Lactobacillus rhamnosus GG (LGG) and Lactobacillus delbrueckii subsp. bulgaricus (L.del) on the expression of TLR4 and signalling factors such as p38 MAPK and I?B at transcription level in human monocyte-derived dendritic cells (DCs). Our findings demonstrated that even inactivated probiotic strains can affect TLR4 expression in a down-regulatory direction as with lipopolysaccharides after 12 hours. LGG significantly down-regulated expression of p38 while I?B expression was significantly reduced in L.del-treated DCs. Moreover, we found these Lactobacillus strains could even modify the immune response at post-transcriptional level by modifying miRNAs expression. Based on our results LGG induced a significant down-regulatory effect on miR-146a expression which is known as a novel fine negative regulator of immune response targeting NFκB. On the other hand, miR-155 was up-regulated by LGG which is consistent with down-regulation of p38 and in LGG-treated DCs. These findings provide genetic and epigenetic explanations for the responsible underlying mechanisms by which probiotics influence immune response by targeting DCs.