Pathological concentrations of homocysteine increases IL-1β production in macrophages in a P2X7, NF-ĸB, and erk-dependent manner

The role of Pannexin-1 channels, ATP, and purinergic receptors in the pathogenesis of HIV and SARS-CoV-2

Infectious agents such as human immune deficiency virus-1 (HIV) and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) use host proteins to infect, replicate, and induce inflammation within the host. A critical component of these diseases is the axis between pannexin-1 channels, extracellular ATP, and purinergic receptors. Here, we describe the potential therapeutic role of Pannexin-1/purinergic approaches to prevent or reduce the devastating consequences of these pathogens.

The Controversial Role of HCY and Vitamin B Deficiency in Cardiovascular Diseases

Plasma homocysteine (HCY) is an established risk factor for cardiovascular disease CVD and stroke. However, more than two decades of intensive research activities has failed to demonstrate that Hcy lowering through B-vitamin supplementation results in a reduction in CVD risk. Therefore, doubts about a causal involvement of hyperhomocysteinemia (HHcy) and B-vitamin deficiencies in atherosclerosis persist. Existing evidence indicates that HHcy increases oxidative stress, causes endoplasmatic reticulum (ER) stress, alters DNA methylation and, thus, modulates the expression of numerous pathogenic and protective genes. Moreover, Hcy can bind directly to proteins, which can change protein function and impact the intracellular redox state. As most mechanistic evidence is derived from experimental studies with rather artificial settings, the relevance of these results in humans remains a matter of debate. Recently, it has also been proposed that HHcy and B-vitamin deficiencies may promote CVD through accelerated telomere shortening and telomere dysfunction. This review provides a critical overview of the existing literature regarding the role of HHcy and B-vitamin deficiencies in CVD. At present, the CVD risk associated with HHcy and B vitamins is not effectively actionable. Therefore, routine screening for HHcy in CVD patients is of limited value. However, B-vitamin depletion is rather common among the elderly, and in such cases existing deficiencies should be corrected. While Hcy-lowering with high doses of B vitamins has no beneficial effects in secondary CVD prevention, the role of Hcy in primary disease prevention is insufficiently studied. Therefore, more intervention and experimental studies are needed to address existing gaps in knowledge.

Current progress on the mechanisms of hyperhomocysteinemia-induced vascular injury and use of natural polyphenol compounds

Cardiovascular disease is one of the most common diseases in the elderly population, and its incidence has rapidly increased with the prolongation of life expectancy. Hyperhomocysteinemia is an independent risk factor for various cardiovascular diseases, including atherosclerosis, and damage to vascular function plays an initial role in its pathogenesis. This review presents the latest knowledge on the mechanisms of vascular injury caused by hyperhomocysteinemia, including oxidative stress, endoplasmic reticulum stress, protein N-homocysteinization, and epigenetic modification, and discusses the therapeutic targets of natural polyphenols. Studies have shown that natural polyphenols in plants can reduce homocysteine levels and regulate DNA methylation by acting on oxidative stress and endoplasmic reticulum stress-related signaling pathways, thus improving hyperhomocysteinemia-induced vascular injury. Natural polyphenols obtained via daily diet are safer and have more practical significance in the prevention and treatment of chronic diseases than traditional drugs.

Functioning of Long Noncoding RNAs Expressed in Macrophage in the Development of Atherosclerosis

Chronic inflammation is part of the pathological process during atherosclerosis (AS). Due to the abundance of monocytes/macrophages within the arterial plaque, monocytes/macrophages have become a critical cellular target in AS studies. In recent decades, a number of long noncoding RNAs (lncRNAs) have been found to exert regulatory roles on the macrophage metabolism and macrophage plasticity, consequently promoting or suppressing atherosclerotic inflammation. In this review, we provide a comprehensive overview of lncRNAs in macrophage biology, highlighting the potential role of lncRNAs in AS based on recent findings, with the aim to identify disease biomarkers and future therapeutic interventions for AS.

The yin and yang functions of extracellular ATP and adenosine in tumor immunity

Extracellular adenosine triphosphate (eATP) and its main metabolite adenosine (ADO) constitute an intrinsic part of immunological network in tumor immunity. The concentrations of eATP and ADO in tumor microenvironment (TME) are controlled by ectonucleotidases, such as CD39 and CD73, the major ecto-enzymes expressed on immune cells, endothelial cells and cancer cells. Once accumulated in TME, eATP boosts antitumor immune responses, while ADO attenuates immunity against tumors. eATP and ADO, like yin and yang, represent two opposite aspects from immune-activating to immune-suppressive signals. Here we reviewed the functions of eATP and ADO in tumor immunity and attempt to block eATP hydrolysis, ADO formation and their contradictory effects in tumor models, allowing the induction of effective anti-tumor immune responses in TME. These attempts documented that therapeutic approaches targeting eATP/ADO metabolism and function may be effective methods in cancer therapy.

Neurotrophins of the Fetal Brain and Placenta in Prenatal Hyperhomocysteinemia

Prenatal hyperhomocysteinemia (PHHC) in pregnant rats was induced by chronic L-methionine loading, resulting in a significant increase in the L-homocysteine content both in the mothers' blood and blood and brain of fetuses. Significant decrease in the weight of the placenta, fetus, and fetal brain was detected by the morphometric studies on day 20 of pregnancy. PHHC also activated maternal immune system due to the increase in the content of proinflammatory interleukin-1β in the rat blood and fetal part of the placenta. PHHC elevated the levels of the brain-derived neurotrophic factor (BDNF, 29 kDa) and nerve growth factor (NGF, 31 kDa) precursors in the placenta and the content of the BDNF isoform (29 kDa) in the fetal brain. The content of neuregulin 1 (NRG1) decreased in the placenta and increased in the fetal brain on day 20 of embryonic development. An increase in the caspase-3 activity was detected in the brains of fetuses subjected to PHHC. It was suggested that changes in the processing of neurotrophins induced by PPHC, oxidative stress, and inflammatory processes initiated by it, as well as apoptosis, play an important role in the development of brain disorders in the offspring.

IL‑37 expression is decreased in patients with hyperhomocysteinemia and protects cells from inflammatory injury by homocysteine

As a novel anti‑inflammatory cytokine of the interleukin (IL)‑1 family, IL‑37 protects the human body from diseases characterized by excessive inflammation. The pathologic process of hyperhomocysteinemia (hHcy) is accompanied by persistent inflammation. However, little is known regarding the role of IL‑37 in hHcy. In the present study, the levels of cytokines including IL‑37, IL‑1β, IL‑6 and tumor necrosis factor‑α in the supernatant were detected by ELISA. mRNA and protein expression were detected by Reverse transcription‑quantitative PCR and western blotting, respectively. LDH level was determined by ELISA and the cell viability was detected through CCK‑8 kit. In the present study, mean serum IL‑37 levels of patients with hHcy were 32.3% lower than those of controls (P<0.01). In peripheral blood mononuclear cells (PBMCs) from patients with hHcy, mean IL‑37 mRNA expression was 73.5% lower (P<0.01) and IL‑37 protein expression was 77.7% lower compared with that of healthy controls (P<0.01). Furthermore, the results demonstrated that exogenous homocysteine (Hcy) stimulation markedly downregulated the mRNA and protein expression levels of IL‑37 in PBMCs in vitro. In 293T cells, overexpression of IL‑37 restored the cell viability impaired by Hcy, and reduced the release of lactate dehydrogenase and the proinflammatory cytokines IL‑1β, IL‑6 and tumor necrosis factor‑α. In conclusion, IL‑37 was downregulated by Hcy in vivo and in vitro, and IL‑37 exhibited a protective role against cell injury induced by Hcy.

ATP/P2X7 receptor signaling as a potential anti-inflammatory target of natural polyphenols

Innate immune cells, such as macrophages, respond to pathogen-associated molecular patterns, such as a lipopolysaccharide (LPS), to secrete various inflammatory mediators. Recent studies have suggested that damage-associated molecular patterns (DAMPs), released extracellularly from damaged or immune cells, also play a role in the activation of inflammatory responses. In this study, to prevent excess inflammation, we focused on DAMPs-mediated signaling that promotes LPS-stimulated inflammatory responses, especially adenosine 5’-triphosphate (ATP)-triggered signaling through the ionotropic purinergic receptor 7 (P2X7R), as a potential new anti-inflammatory target of natural polyphenols. We focused on the phenomenon that ATP accelerates the production of inflammatory mediators, such as nitric oxide, in LPS-stimulated J774.1 mouse macrophages. Using an siRNA-mediated knockdown and specific antagonist, it was found that the ATP-induced enhanced inflammatory responses were mediated through P2X7R. We then screened 42 polyphenols for inhibiting the ATP/P2X7R-induced calcium influx, and found that several polyphenols exhibited significant inhibitory effects. Especially, a flavonoid baicalein significantly inhibited ATP-induced inflammation, including interleukin-1β secretion, through inhibition of the ATP/P2X7R signaling. These findings suggest that ATP/P2X7R signaling plays an important role in excess inflammatory responses and could be a potential anti-inflammatory target of natural polyphenolic compounds.

Homocysteine and homocysteine-related compounds: an overview of the roles in the pathology of the cardiovascular and nervous systems

Homocysteine, an amino acid containing a sulfhydryl group, is an intermediate product during metabolism of the amino acids methionine and cysteine. Hyperhomocysteinemia is used as a predictive risk factor for cardiovascular disorders, the stroke progression, screening for inborn errors of methionine metabolism, and as a supplementary test for vitamin B₁₂ deficiency. Two organic systems in which homocysteine has the most harmful effects are the cardiovascular and nervous system. The adverse effects of homocysteine are achieved by the action of several different mechanisms, such as overactivation of N-methyl-d-aspartate receptors, activation of Toll-like receptor 4, disturbance in Ca²⁺ handling, increased activity of nicotinamide adenine dinucleotide phosphate-oxidase and subsequent increase of production of reactive oxygen species, increased activity of nitric oxide synthase and nitric oxide synthase uncoupling and consequent impairment in nitric oxide and reactive oxygen species synthesis. Increased production of reactive species during hyperhomocysteinemia is related with increased expression of several proinflammatory cytokines, including IL-1β, IL-6, TNF-α, MCP-1, and intracellular adhesion molecule-1. All these mechanisms contribute to the emergence of diseases like atherosclerosis and related complications such as myocardial infarction, stroke, aortic aneurysm, as well as Alzheimer disease and epilepsy. This review provides evidence that supports the causal role for hyperhomocysteinemia in the development of cardiovascular disease and nervous system disorders.

The methylenetetrahydrofolate reductase genotype 677CT and non-alcoholic fatty liver disease have a synergistic effect on the increasing homocysteine levels in subjects from Chongqing, China

The methylenetetrahydrofolate reductase (MTHFR) genotypes 677CT and 677TT are associated with elevated serum homocysteine (Hcy) levels by means of lowering the activity of MTHFR, and the increase in serum Hcy may be linked to increased susceptibility to non-alcoholic fatty liver disease (NAFLD). However, there are contradictory reports of the relationship among the MTHFR 677CT gene polymorphism, Hcy, and NAFLD. Therefore, the aim of this study was to identify potential associations and interactions of either Hcy levels or the MTHFR 677CT gene polymorphism with the susceptibility to NAFLD in a Chinese population. The association between the MTHFR 677 CT gene polymorphism and Hcy levels was determined in 243 subjects with NAFLD and 388 healthy subjects without NAFLD using polymerase chain reaction-restriction fragment length polymorphism analysis and high-performance liquid chromatography. In subjects with NAFLD, there was no statistical difference in the genotypic and allelic frequencies of the MTHFR 677 CT gene polymorphism, while serum Hcy levels were significantly higher in subjects with NAFLD. Furthermore, these results strongly suggest that the MTHFR 677CT gene polymorphism and NAFLD have a potential synergistic effect on Hcy elevation, although the MTHFR 677CT gene polymorphism was not correlated with NAFLD in a Chinese population.

Extracellular ATP Activates the NLRP3 Inflammasome and Is an Early Danger Signal of Skin Allograft Rejection

Immune cells are equipped with a number of receptors that recognize sterile injury and pathogens. We find that host immune cells release ATP as an inflammatory signal in response to allogeneic transplantation. ATP then acts via a feedback mechanism on the P2X7 channel to activate the NLRP3 inflammasome and subsequently process and release interleukin (IL)-18. This process is a necessary stage in the deleterious Th1 response against allotransplantation via interferon-γ production. Lack of IL-18 resulted in a decrease in graft-infiltrating CD8 cells but an increase in regulatory T cells. In human liver transplant patients undergoing progressive immunosuppressive drug withdrawal, we found that patients experiencing acute rejection had higher levels of the P2X7 receptor in circulating inflammatory monocytes compared to tolerant patients. These data suggest that the pharmacological inhibition of the P2X7 receptor or the NLRP3 inflammasome will aid in inducing transplant tolerance without complete immunoparalysis.

Homocysteine induces vascular inflammatory response via SMAD7 hypermethylation in human umbilical vein smooth muscle cells

Homocysteine (Hcy) can induce atherosclerosis through the inflammatory response and DNA methylation disorder. Our recent study has reported a novel epigenetic modified gene related to atherosclerosis -SMAD7. To further understand the pathogenesis of atherosclerosis, the current study was designed to investigate an inflammatory role of Hcy in human umbilical vein smooth muscle cells (HUVSMCs) through interfering with SMAD7 methylation. Using MALDI-TOF MS, we found that Hcy increased DNA methylation levels of SMAD7 promoter in a dose and time-dependent manner in HUVSMCs. Meanwhile, both SMAD7 mRNA and protein levels were decreased along with the increase of Hcy concentrations and treating time. Decreased SMAD7 levels led to up regulation of pro-inflammatory cytokines (TNF-α and IL-1β) expression in HUVSMCs. Furthermore, we found that activation of NF-κB pathway was the mechanism by which reduced Smad7 levels enhanced vascular inflammation. Thus, Hcy is able to activate NF-κB-mediated vascular inflammatory response via inducing hypermethylation of SMAD7 promoter in HUVSMCs. The in vitro findings supplement our recent clinical study that SMAD7 methylation as a novel marker in atherosclerosis and further elucidate the role of Hcy in atherogenesis.

LncRNA uc.48+ is involved in the diabetic immune and inflammatory responses mediated by P2X7 receptor in RAW264.7 macrophages

High glucose combined with high FFAs can contribute to the unfavorable development of type 2 diabetes mellitus (T2DM) and monocytes/macrophages are important in the occurrence and development of T2DM, which is regarded as a type of low‑grade inflammation. Although our previous study demonstrated that increased expression of P2X7 receptor (P2X7R) in peripheral blood monocytes may alter the innate immune system and that long non‑coding (lnc)RNA uc.48+ was involved in diabetic neuropathic pain, the involvement of uc.48+ mediated by the P2X7R in monocyte/macrophages during T2DM has not been reported. In the present study, the effectsof uc.48+ small interference RNA (siRNA) on factors, including the mRNA and protein expression of P2X7R, apoptosis and proliferation, levels of reactive oxygen species (ROS), cytokine levels, and expression of phosphorylated (p‑) extracellular signal‑regulated kinase (ERK)1/2, were examined in RAW264.7 macrophages following exposure to high glucose and high plasma free fatty acids (FFAs). After RAW264.7 cells were transfected with uc.48+ siRNA under high glucose conditions and FFAs treatment, the mRNA expression levels of uc.48+ and P2X7 receptor were detected by reverse transcription‑polymerase chain reaction. The protein mass of P2X7 receptor and ERK signaling pathway were assessed by western blotting. ROS and calcium concentrations, and culture supernatant cytokine content [tumor necrosis factor‑α, interleukin (IL)‑10, IL‑1β] were detected by fluorescent probes and ELISA respectively. Cell viability and apoptosis were determined by MTS test and flow cytometry, respectively. It was found that treatment of RAW264.7 cells with high glucose and FFAs, which exhibited increased expression of uc.48+, evoked P2X7R‑mediated immune and inflammatory responses through several means, including cytokine secretion, ROS formation, and activation of the ERK signaling pathway. The uc.48+ siRNA regulated these factors and thus influenced the course and outcome of the immune and inflammatory responses mediated by P2X7R.

Detection of Endothelial Dysfunction Using Skin Temperature Oscillations Analysis During Local Heating in Patients With Peripheral Arterial Disease

OBJECTIVE

The purpose of this study was to examine correlations between laboratory markers of ED and the degree of endothelium-dependent vasodilation using WAST during a local heating test in patients with PAD.

MATERIALS AND METHODS

The study population consisted of 17 healthy subjects and 38 patients with PAD. The ST on the plantar surface of the first toe was measured during the test, and the inverse wavelet transform was applied to reconstruct the ST signals in three frequency bands corresponding to myogenic, neurogenic, and endothelial mechanisms of vascular tone regulation.

RESULTS

In healthy subjects, a local increase in temperature of up to 42°C caused a greater than threefold increase in the amplitudes of foot ST oscillations. Among patients with PAD, the response to the test was much weaker in all frequency ranges. The level of vasodilation dysfunction correlated with the level of artery stenosis in the lower extremities and with laboratory markers of ED (endothelin, homocysteine, and von Willebrand factor).

CONCLUSION

WAST can be considered as a low cost, portable, and easy to use technique for the noninvasive assessment of ED.

Geniposide attenuates Aβ25–35-induced neurotoxicity via the TLR4/NF-κB pathway in HT22 cells

Alzheimer's disease (AD), a neurodegenerative disorder, is marked by the accumulation of amyloid-β (Aβ) and neuroinflammation which promote the development of AD. Geniposide, the main ingredient isolated from Chinese herbal medicine Gardenia jasminoides Ellis, has a variety of pharmacological functions such as anti-apoptosis and anti-inflammatory activity. Hence, we estimated the inflammatory cytotoxicity caused by Aβ_25–35 and the neuroprotective effects of geniposide in HT22 cells. In this research, following incubation with Aβ_25–35 (40 μM, 24 h) in HT22 cells, the methylthiazolyl tetrazolium (MTT) and lactate dehydrogenase (LDH) release assays showed that the cell survival rate was significantly decreased. In contrast, the reactive oxygen species (ROS) assay indicated that Aβ_25–35 enhanced ROS accumulation and apoptosis showed in both hoechst 33342 staining and annexin V-FITC/PI double staining. And then, immunofluorescence test revealed that Aβ_25–35 promoted p65 to transfer into the nucleus indicating p65 was activated by Aβ_25–35. Moreover, western blot analysis proved that Aβ_25–35 increased the expression of nitric oxide species (iNOS), tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2) and interleukin-1β (IL-1β). Simultaneously, Aβ_25–35 also promoted the expression of toll-like receptor 4 (TLR4), p-p65 and p-IκB-α accompanied with the increase in the level of beta-secretase 1 (BACE1) and caspase-3 which further supported Aβ_25–35 induced apoptosis and inflammation. Fortunately, this up-regulation was reversed by geniposide. In conclusion, our data suggest that geniposide can alleviate Aβ_25–35-induced inflammatory response to protect neurons, which is possibly involved with the inhibition of the TLR4/NF-κB pathway in HT22 cells. Geniposide may be the latent treatment for AD induced by neuroinflammation and apoptosis.

Alzheimer's disease (AD), a neurodegenerative disorder, is marked by the accumulation of amyloid-β (Aβ) and neuroinflammation which promote the development of AD.

Pyridoxine Deficiency After Solid Organ Transplant

OBJECTIVE

Pyridoxine is 1 of 8 B vitamins that assist in a variety of essential functions including immune functions. The purpose of this study was to assess the risk factors associated with low pyridoxine levels in solid organ transplantation recipients.

DESIGN

The study cohort was divided into 2 groups: (a) patients with normal pyridoxine levels or (b) patients with low pyridoxine levels. Dietary evaluation and clinical characteristics of all patients, rejection episodes, and immunosuppression were collected. Simple descriptive statistics were used to analyze the overall cohort.

RESULTS

Of the 48 patients, 29 (60%) in the study cohort were identified to have low pyridoxine levels. The mean interval between transplantation and pyridoxine level check was 910 days (standard deviation [SD] 456). The mean weight at the time of dietary consultation was 80 kg (SD 20.7). More patients in the deficient group received thymoglobulin for rejection treatment (56% vs 0%; P = .01) and were thymoglobulin recipients (78% vs 10%; odds ratio [OR] = 31.5; 95% confidence interval [CI], 2.35-422.30; P < .01). A strong correlation was identified between thymoglobulin treatment for induction and a low level of pyridoxine (correlation coefficient R = 0.6, P = .004) and between thymoglobulin treatment for rejection and a low pyridoxine level (correlation coefficient R = 0.5, P = .05). Based on multivariate logistic regression analysis, only thymoglobulin treatment (induction or rejection treatment) was significantly associated with low pyridoxine levels (OR = 19.5, 95% CI, 1.01-375.24; P < .05).

CONCLUSIONS

Low levels of pyridoxine appear to be relatively common, and thymoglobulin treatments are associated with low pyridoxine levels. Prospective studies are needed to confirm and valuate the significance of these findings.

Hyperhomocysteinaemia and vascular injury: advances in mechanisms and drug targets

Homocysteine is a sulphur-containing non-proteinogenic amino acid. Hyperhomocysteinaemia (HHcy), the pathogenic elevation of plasma homocysteine as a result of an imbalance of its metabolism, is an independent risk factor for various vascular diseases, such as atherosclerosis, hypertension, vascular calcification and aneurysm. Treatments aimed at lowering plasma homocysteine via dietary supplementation with folic acids and vitamin B are more effective in preventing vascular disease where the population has a normally low folate consumption than in areas with higher dietary folate. To date, the mechanisms of HHcy-induced vascular injury are not fully understood. HHcy increases oxidative stress and its downstream signalling pathways, resulting in vascular inflammation. HHcy also causes vascular injury via endoplasmic reticulum stress. Moreover, HHcy up-regulates pathogenic genes and down-regulates protective genes via DNA demethylation and methylation respectively. Homocysteinylation of proteins induced by homocysteine also contributes to vascular injury by modulating intracellular redox state and altering protein function. Furthermore, HHcy-induced vascular injury leads to neuronal damage and disease. Also, an HHcy-activated sympathetic system and HHcy-injured adipose tissue also cause vascular injury, thus demonstrating the interactions between the organs injured by HHcy. Here, we have summarized the recent developments in the mechanisms of HHcy-induced vascular injury, which are further considered as potential therapeutic targets in this condition.

LINKED ARTICLES

This article is part of a themed section on Spotlight on Small Molecules in Cardiovascular Diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.8/issuetoc.

Targeting methionine cycle as a potential therapeutic strategy for immune disorders

INTRODUCTION

Methionine cycle plays an essential role in regulating many cellular events, especially transmethylation reactions, incorporating the methyl donor S-adenosylmethionine (SAM). The transmethylations and substances involved in the cycle have shown complicated effects and mechanisms on immunocytes developments and activations, and exert crucial impacts on the pathological processes in immune disorders. Areas covered: Methionine cycle has been considered as an effective means of drug developments. This review discussed the role of methionine cycle in immune responses and summarized the potential therapeutic strategies based on the cycle, including SAM analogs, methyltransferase inhibitors, S-adenosylhomocysteine hydrolase (SAHH) inhibitors, adenosine receptors specific agonists or antagonists and homocysteine (Hcy)-lowering reagents, in treating human immunodeficiency virus (HIV) infections, systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), multiple sclerosis (MS), systemic sclerosis (SSc) and other immune disorders. Expert opinion: New targets and biomarkers grown out of methionine cycle have developed rapidly in the past decades. However, impacts of epigenetic regulations on immune disorders are unclear and whether the substances in methionine cycle can be clarified as biomarkers remains controversial. Therefore, further elucidation on the role of epigenetic regulations and substances in methionine cycle may contribute to exploring the cycle-derived biomarkers and drugs in immune disorders.

l-Homocysteine-induced cathepsin V mediates the vascular endothelial inflammation in hyperhomocysteinaemia

BACKGROUND AND PURPOSE

Vascular inflammation, including the expression of inflammatory cytokines in endothelial cells, plays a critical role in hyperhomocysteinaemia-associated vascular diseases. Cathepsin V, specifically expressed in humans, is involved in vascular diseases through its elastolytic and collagenolytic activities. The aim of this study was to determine the effects of cathepsin V on l-homocysteine-induced vascular inflammation.

EXPERIMENTAL APPROACH

A high methionine diet-induced hyperhomocysteinaemic mouse model was used to assess cathepsin V expression and vascular inflammation. Cultures of HUVECs were challenged with l-homocysteine and the cathepsin L/V inhibitor SID to assess the pro-inflammatory effects of cathepsin V. Transfection and antisense techniques were utilized to investigate the effects of cathepsin V on the dual-specificity protein phosphatases (DUSPs) and MAPK pathways.

KEY RESULTS

Cathepsin L (human cathepsin V homologous) was increased in the thoracic aorta endothelial cells of hyperhomocysteinaemic mice; l-homocysteine promoted cathepsin V expression in HUVECs. SID suppressed the activity of cathepsin V and reversed the up-regulation of inflammatory cytokines (IL-6, IL-8 and TNF-α), adhesion and chemotaxis of leukocytes and vascular inflammation induced by l-homocysteine in vivo and in vitro. Increased cathepsin V promoted the degradation of DUSP6 and DUSP7, phosphorylation and subsequent nuclear translocation of ERK1/2, phosphorylation of STAT1 and expression of IL-6, IL-8 and TNF-α.

CONCLUSIONS AND IMPLICATIONS

This study has identified a novel mechanism, which shows that l-homocysteine-induced upregulation of cathepsin V mediates vascular endothelial inflammation under high homocysteine condition partly via ERK_1/2 /STAT1 pathway. This mechanism could represent a potential therapeutic target in hyperaemia-associated vascular diseases.

LINKED ARTICLES

This article is part of a themed section on Spotlight on Small Molecules in Cardiovascular Diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.8/issuetoc.

Activation of Eosinophils Interacting with Bronchial Epithelial Cells by Antimicrobial Peptide LL-37: Implications in Allergic Asthma

The role of antimicrobial peptide LL-37 in asthma exacerbation is unclear. Microbial infection, which is the most common inducer of asthma exacerbation, is accompanied by elevated LL-37. The present study found that co-culture of eosinophils and bronchial epithelial cell line BEAS-2B significantly enhanced intercellular adhesion molecule-1 on both cells and CD18 expression on eosinophils upon LL-37 stimulation. IL-6, CXCL8 and CCL4 were substantially released in co-culture in the presence of LL-37. LL-37 triggered the activation of eosinophils interacting with BEAS-2B cells in a P2X purinoceptor 7/epidermal growth factor receptor-dependent manner. Eosinophils and BEAS-2B cells differentially contribute to the expression of cytokines/chemokines in co-culture, while soluble mediators were sufficient to mediate the intercellular interactions. Intracellular p38-mitogen-activated protein kinase, extracellular signal-regulated kinase and NF-κB signaling pathways were essential for LL-37-mediated activation of eosinophils and BEAS-2B cells. By using the ovalbumin-induced asthmatic model, intranasal administration of mCRAMP (mouse ortholog of LL-37) in combination with ovalbumin during the allergen challenge stage significantly enhanced airway hyperresponsiveness and airway inflammation in sensitized mice, thereby implicating a deteriorating role of LL-37 in allergic asthma. This study provides evidence of LL-37 in triggering asthma exacerbation via the activation of eosinophils interacting with bronchial epithelial cells in inflammatory airway.

Toll-like receptor 4 mediates vascular remodeling in hyperhomocysteinemia

Although hyperhomocysteinemia (HHcy) is known to promote downstream pro-inflammatory cytokine elevation, the precise mechanism is still unknown. One of the possible receptors that could have significant attention in the field of hypertension is toll-like receptor 4 (TLR-4). TLR-4 is a cellular membrane protein that is ubiquitously expressed in all cell types of the vasculature. Its mutation can attenuate the effects of HHcy-mediated vascular inflammation and mitochondria- dependent cell death that suppresses hypertension. In this review, we observed that HHcy induces vascular remodeling through immunological adaptation, promoting inflammatory cytokine up-regulation (IL-1β, IL-6, TNF-α) and initiation of mitochondrial dysfunction leading to cell death and chronic vascular inflammation. The literature suggests that HHcy promotes TLR-4-driven chronic vascular inflammation and mitochondria-mediated cell death inducing peripheral vascular remodeling. In the previous studies, we have characterized the role of TLR-4 mutation in attenuating vascular remodeling in hyperhomocysteinemia. This review includes, but is not limited to, the physiological synergistic aspects of the downstream elevation of cytokines found within the vascular inflammatory cascade. These events subsequently induce mitochondrial dysfunction defined by excessive mitochondrial fission and mitochondrial apoptosis contributing to vascular remodeling followed by hypertension.

Toll-like receptor 4 mutation suppresses hyperhomocysteinemia-induced hypertension

Hyperhomocysteinemia (HHcy) has been observed to promote hypertension, but the mechanisms are unclear. Toll-like receptor 4 (TLR-4) is a cellular membrane protein that is ubiquitously expressed in all cell types of the vasculature. TLR-4 activation has been known to promote inflammation that has been associated with the pathogenesis of hypertension. In this study we hypothesize that HHcy induces hypertension by TLR-4 activation, which promotes inflammatory cytokine (IL-1β, IL-6, and TNF-α) upregulation and initiation of mitochondria-dependent apoptosis, leading to cell death and chronic vascular inflammation. To test this hypothesis, we used C57BL/6J (WT) mice, cystathionine β-synthase (CBS)-deficient (CBS^+/-) mice with genetic mild HHcy, C3H/HeJ (C3H) mice with TLR-4 mutation, and mice with combined genetic HHcy and TLR-4 mutation (CBS^+/-/C3H). Ultrasonography of the superior mesenteric artery (SMA) detected an increase in wall-to-lumen ratio, resistive index (RI), and pulsatility index (PI). Tail cuff blood pressure (BP) measurement revealed elevated BP in CBS^+/- mice. RI, PI, and wall-to-lumen ratio of the SMA in CBS^+/-/C3H mice were similar to the control group, and BP was significantly alleviated. TLR-4, IL-1β, IL-6, and TNF-α expression were upregulated in the SMA of CBS^+/- mice and reduced in the SMA of CBS^+/-/C3H mice. Molecules involved in the mitochondria-mediated cell death pathway (BAX, caspase-9, and caspase-3) were upregulated in CBS^+/- mice and attenuated in CBS^+/-/C3H mice. We conclude that HHcy promotes TLR-4-driven chronic vascular inflammation and mitochondria-mediated cell death, inducing hypertension. TLR-4 mutation attenuates vascular inflammation and cell death, which suppress hypertension.

Tolerability and efficacy study of P2X7 inhibition in experimental Charcot-Marie-Tooth type 1A (CMT1A) neuropathy

Charcot-Marie-Tooth 1A (CMT1A) is a demyelinating hereditary neuropathy for which pharmacological treatments are not yet available. An abnormally high intracellular Ca(2+) concentration was observed in Schwann cells (SC) from CMT1A rats, caused by the PMP22-mediated overexpression of the P2X7 purinoceptor. The purpose of this study was to investigate the tolerability and therapeutic potential of a pharmacological antagonist of the P2X7 receptor (A438079) in CMT1A. A438079 ameliorated in vitro myelination of organotypic DRG cultures from CMT1A rats. Furthermore, we performed an experimental therapeutic trial in PMP22 transgenic and in wild-type rats. A preliminary dose-escalation trial showed that 3mg/kg A438079 administered via intraperitoneal injection every 24h for four weeks was well tolerated by wild type and CMT1A rats. Affected rats treated with 3mg/kg A438079 revealed a significant improvement of the muscle strength, when compared to placebo controls. Importantly, histologic analysis revealed a significant increase of the total number of myelinated axons in tibial nerves. Moreover, a significant decrease of the hypermyelination of small caliber axons and a significant increase of the frequency and diameter of large caliber myelinated axons was highlighted. An improved distal motor latencies was recorded, whereas compound muscle action potentials (CMAP) remained unaltered. A438079 reduced the SC differentiation defect in CMT1A rats. These results show that pharmacological inhibition of the P2X7 receptor is well tolerated in CMT1A rats and represents a proof-of-principle that antagonizing this pathway may correct the molecular derangements and improve the clinical phenotype in the CMT1A neuropathy.

Plasma S-adenosylhomocysteine: A potential risk marker for cerebral venous thrombosis

BACKGROUND

Despite a plethora of studies suggesting that hyperhomocysteinemia is associated with an increased risk for arterial and venous thrombosis, there is paucity of data on the role of the S-adenosylhomocysteine (SAH), the metabolic precursor of homocysteine (Hcy) as a risk predictor for cerebral venous thrombosis (CVT).

METHOD

We estimated fasting plasma concentrations of total homocysteine (tHcy), SAH and S-adenosylmethionine (SAM), in 185 CVT patients and 248 healthy controls, by reverse-phase high performance liquid chromatography coupled with coulometric electrochemical detection.

RESULTS

Fasting tHcy, SAH and SAM were significantly higher in patients compared with controls. Increased tHcy and SAH concentrations were associated with 4.54-fold (95% CI, 2.74-7.53) and 35.77-fold (95% CI, 19.45-65.79) increase in risk for CVT, respectively. Receiver operating characteristic (ROC) curve analysis showed that the area under curve, sensitivity and specificity was higher for SAH compared to tHcy. Further, discriminant analysis to distinguish between tHcy and SAH showed that SAH had a significantly higher percentage classification, with lower Wilk's lambda and higher χ(2), compared to tHcy.

CONCLUSION

Increased plasma SAH may be a more sensitive risk marker for CVT than plasma tHcy.

Procyanidins alleviates morphine tolerance by inhibiting activation of NLRP3 inflammasome in microglia

Background

The development of antinociceptive tolerance following repetitive administration of opioid analgesics significantly hinders their clinical use. Evidence has accumulated indicating that microglia within the spinal cord plays a critical role in morphine tolerance. The inhibitor of microglia is effective to attenuate the tolerance; however, the mechanism is not fully understood. Our present study investigated the effects and possible mechanism of a natural product procyanidins in improving morphine tolerance via its specific inhibition on NOD-like receptor protein3 (NLRP3) inflammasome in microglia.

Methods

CD-1 mice were used for tail-flick test to evaluate the degree of pain. The microglial cell line BV-2 was used to investigate the effects and the mechanism of procyanidins. Reactive oxygen species (ROS) produced from BV-2 cells was evaluated by flow cytometry. Cell signaling was measured by western blot assay and immunofluorescence assay.

Results

Co-administration of procyanidins with morphine potentiated its antinociception effect and attenuated the development of acute and chronic morphine tolerance. Procyanidins also inhibited morphine-induced increase of interleukin-1β and activation of NOD-like receptor protein3 (NLRP3) inflammasome. Furthermore, procyanidins decreased the phosphorylation of p38 mitogen-activated protein kinase, inhibited the translocation of nuclear factor-κB (NF-κB), and suppressed the level of reactive oxygen species in microglia.

Conclusions

Procyanidins suppresses morphine-induced activation of NLRP3 inflammasome and inflammatory responses in microglia, and thus resulting in significant attenuation of morphine antinociceptive tolerance.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0520-z) contains supplementary material, which is available to authorized users.

Genetic risk factors for spontaneous intracerebral haemorrhage

Intracerebral haemorrhage (ICH) is associated with the greatest morbidity and mortality of all stroke subtypes. Established risk factors for ICH include hypertension, alcohol use, current cigarette smoking, and use of oral anticoagulants and/or antiplatelet agents. Familial aggregation of ICH has been observed, and the heritability of ICH risk has been estimated at 44%. Few genes have been found to be associated with ICH at the population level, and much of the evidence for genetic risk factors for ICH comes from single studies conducted in relatively small and homogenous populations. In this Review, we summarize the current knowledge of genetic variants associated with primary spontaneous ICH. Two variants of the gene encoding apolipoprotein E (APOE) - which also contributes to the pathogenesis of cerebral amyloid angiopathy - are the most likely candidates for variants that increase the risk of ICH. Other promising candidates for risk alleles in ICH include variants of the genes ACE, PMF1/SLC25A44, COL4A2, and MTHFR. Other genetic variants, related to haemostasis, lipid metabolism, inflammation, and the CNS microenvironment, have been linked to ICH in single candidate gene studies. Although evidence for genetic contributions to the risk of ICH exists, we do not yet fully understand how and to what extent this information can be utilized to prevent and treat ICH.