Interleukin-4 regulates macrophage polarization via the MAPK signaling pathway to protect against atherosclerosis

γ-Glutamylcysteine rescues mice from TNBS-driven inflammatory bowel disease through regulating macrophages polarization

OBJECTIVE

To explore the molecular mechanism of γ-glutamylcysteine (γ-GC) in response to inflammation in vivo and in vitro on regulating the polarization of macrophages.

METHODS

The expressions of gene or protein were assessed by qPCR and Western blot assays, respectively. Cell viability was investigated by CCK-8 assay. Eight-week-old male BALB/c mice were established to examine the therapeutic effects of γ-GC in vivo. The release of TNF-α and IL-4 was determined by ELISA assay. Macrophages polarization was identified by flow cytometry assay.

RESULTS

Our data showed that γ-GC treatment significantly improved the survival, weight loss, and colon tissue damage of IBD mice. Furthermore, we established M1- and M2-polarized macrophages, respectively, and our findings provided evidence that γ-GC switched M1/M2-polarized macrophages through activating AMPK/SIRT1 axis and inhibiting inflammation-related signaling pathway.

CONCLUSION

Collectively, both in vivo and in vitro experiments suggested that γ-GC has the potential to become a promising novel therapeutic dipeptide for the treatment of IBD, which provide new ideas for the treatment of inflammatory diseases in the future.

Targeting macrophages in atherosclerosis using nanocarriers loaded with liver X receptor agonists: A narrow review

Macrophages are involved in the whole process of atherosclerosis, which is characterized by accumulation of lipid and inflammation. Presently, clinically used lipid-lowering drugs cannot completely retard the progress of atherosclerosis. Liver X receptor (LXR) plays a key role in regulation of lipid metabolism and inflammation. Accumulating evidence have demonstrated that synthetic LXR agonists can significantly retard the development of atherosclerosis. However, these agonists induce sever hypertriglyceridemia and liver steatosis. These side effects have greatly limited their potential application for therapy of atherosclerosis. The rapid development of drug delivery system makes it possible to delivery interested drugs to special organs or cells using nanocarriers. Macrophages express various receptors which can recognize and ingest specially modified nanocarriers loaded with LXR agonists. In the past decades, a great progress has been made in this field. These macrophage-targeted nanocarriers loaded with LXR agonists are found to decrease atherosclerosis by reducing cholesterol accumulation and inflammatory reactions. Of important, these nanocarriers can alleviate side effects of LXR agonists. In this article, we briefly review the roles of macrophages in atherosclerosis, mechanisms of action of LXR agonists, and focus on the advances of macrophage-targeted nanocarriers loaded with LXR agonists. This work may promote the potential clinical application of these nanocarriers.

Pro-Healing Nanomatrix-Coated Stent Analysis in an In Vitro Vascular Double-Layer System and in a Rabbit Model

Cardiovascular stent technologies have significantly improved over time. However, their optimal performance remains limited by restenosis, thrombosis, inflammation, and delayed re-endothelialization. Current stent designs primarily target inhibition of neointimal proliferation but do not promote functional arterial healing (pro-healing) in order to restore normal vascular reactivity. The endothelial lining that does develop with current stents appears to have loose intracellular junctions. We have developed a pro-healing nanomatrix coating for stents that enhances healing while limiting neointimal proliferation. This builds on our prior work evaluating the effects of the pro-healing nanomatrix coating on cultures of vascular endothelial cells (ECs), smooth muscle cells (SMCs), monocytes, and platelets. However, when a stent is deployed in an artery, multiple vascular cell types interact, and their interactions affect stent performance. Thus, in our current study, an in vitro vascular double-layer (VDL) system was used to observe stent effects on communication between different vascular cell types. Additionally, we assessed the pro-healing ability and vascular cell interactions after stent deployment in the VDL system and in a rabbit model, evaluating the nanomatrix-coated stent compared to a commercial bare metal stent (BMS) and a drug eluting stent (DES). In vitro results indicated that, in a layered vascular structure, the pro-healing nanomatrix-coated stent could (1) improve endothelialization and endothelial functions, (2) regulate SMC phenotype to reduce SMC proliferation and migration, (3) suppress inflammation through a multifactorial manner, and (4) reduce foam cell formation, extracellular matrix remodeling, and calcification. Consistent with this, in vivo results demonstrated that, compared with commercial BMS and DES, this pro-healing nanomatrix-coated stent enhanced re-endothelialization with negligible restenosis, inflammation, or thrombosis. Thus, these findings indicate the unique pro-healing features of this nanomatrix stent coating with superior efficacy over commercial BMS and DES.

Macrophage Plasticity and Atherosclerosis Therapy

Atherosclerosis is a chronic disease starting with the entry of monocytes into the subendothelium and the subsequent differentiation into macrophages. Macrophages are the major immune cells in atherosclerotic plaques and are involved in the dynamic progression of atherosclerotic plaques. The biological properties of atherosclerotic plaque macrophages determine lesion size, composition, and stability. The heterogenicity and plasticity of atherosclerotic macrophages have been a hotspot in recent years. Studies demonstrated that lipids, cytokines, chemokines, and other molecules in the atherosclerotic plaque microenvironment regulate macrophage phenotype, contributing to the switch of macrophages toward a pro- or anti-atherosclerosis state. Of note, M1/M2 classification is oversimplified and only represent two extreme states of macrophages. Moreover, M2 macrophages in atherosclerosis are not always protective. Understanding the phenotypic diversity and functions of macrophages can disclose their roles in atherosclerotic plaques. Given that lipid-lowering therapy cannot completely retard the progression of atherosclerosis, macrophages with high heterogeneity and plasticity raise the hope for atherosclerosis regression. This review will focus on the macrophage phenotypic diversity, its role in the progression of the dynamic atherosclerotic plaque, and finally discuss the possibility of treating atherosclerosis by targeting macrophage microenvironment.

Dynamic Role of Macrophage Sub Types for Development of Atherosclerosis and Potential Use of Herbal Immunomodulators as Imminent Therapeutic Strategy

Atherosclerosis, a major contributor to cardiovascular disease is a global alarm causing mortality worldwide. Being a progressive disease in the arteries, it mainly causes recruitment of monocytes to the inflammatory sites and subside pathological conditions. Monocyte-derived macrophage mainly acts in foam cell formation by engorging the LDL molecules, oxidizes it into Ox-LDL and leads to plaque deposit development. Macrophages in general differentiate, proliferate and undergo apoptosis at the inflammatory site. Frequently two subtypes of macrophages M1 and M2 has to act crucially in balancing the micro-environmental conditions of endothelial cells in arteries. The productions of proinflammatory mediators like IL-1, IL-6, TNF-α by M1 macrophage has atherogenic properties majorly produced during the early progression of atherosclerotic plaques. To counteract cytokine productions and M1-M2 balance, secondary metabolites (phytochemicals) from plants act as a therapeutic agent in alleviating atherosclerosis progression. This review summarizes the fundamental role of the macrophage in atherosclerotic lesion formation along with its plasticity characteristic as well as recent therapeutic strategies using herbal components and anti-inflammatory cytokines as potential immunomodulators.

Substrate stiffness modulates bone marrow-derived macrophage polarization through NF-κB signaling pathway

The stiffness of the extracellular matrix (ECM) plays an important role in regulating the cellular programming. However, the mechanical characteristics of ECM affecting cell differentiation are still under investigated. Herein, we aimed to study the effect of ECM substrate stiffness on macrophage polarization. We prepared polyacrylamide hydrogels with different substrate stiffness, respectively. After the hydrogels were confirmed to have a good biocompatibility, the bone marrow-derived macrophages (BMMs) from mice were incubated on the hydrogels. With simulated by the low substrate stiffness, BMMs displayed an enhanced expression of CD86 on the cell surface and production of reactive oxygen species (ROS) in cells, and secreted more IL-1β and TNF-α in the supernatant. On the contrary, stressed by the medium stiffness, BMMs expressed more CD206, produced less ROS, and secreted more IL-4 and TGF-β. In vivo study by delivered the hydrogels subcutaneously in mice, more CD68+CD86+ cells around the hydrogels with the low substrate stiffness were observed while more CD68+CD206+ cells near by the middle stiffness hydrogels. In addition, the expressions of NIK, phosphorylated p65 (pi-p65) and phosphorylated IκB (pi-IκB) were significantly increased after stimulation with low stiffness in BMMs. Taken together, these findings demonstrated that substrate stiffness could affect macrophages polarization. Low substrate stiffness promoted BMMs to shift to classically activated macrophages (M1) and the middle one to alternatively activated macrophages (M2), through modulating ROS-initiated NF-κB pathway. Therefore, we anticipated ECM-based substrate stiffness with immune modulation would be under consideration in the clinical applications if necessary.

Neosaxitoxin Inhibits the Expression of Inflammation Markers of the M1 Phenotype in Macrophages

(1) Background: Neosaxitoxin (NeoSTX) has been used as a local anesthetic, but its anti-inflammatory effects have not been well defined. In the present study, we investigate the effects of NeoSTX on lipopolysaccharide (LPS)-activated macrophages. (2) Methods: Raw 264.7 and equine PBMC cells were incubated with or without 100 ng/mL LPS in the presence or absence of NeoSTX (1µM). The expression of inflammatory mediators was assessed: nitric oxide (NO) content using the Griess assay, TNF-α content using the ELISA assay, and mRNA of inducible nitric oxide synthase (iNOS), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) using a real-time polymerase chain reaction. (3) Results: NeoSTX (1 μM) significantly inhibited the release of NO, TNF-α, and expression of iNOS, IL-1β, and TNF-α in LPS-activated macrophages of both species studied. Furthermore, our study shows that the LPS-induced release of inflammatory mediators was suppressed by NeoSTX. Additionally, NeoSTX deactivated polarized macrophages to M1 by LPS without compromising its polarization towards M2. (4) Conclusions: NeoSTX inhibits LPS-induced release of inflammatory mediators from macrophages, and these effects may be mediated by the blockade of voltage-gated sodium channels (VGSC).

Exercise-associated prevention of adult cardiovascular disease in children and adolescents: monocytes, molecular mechanisms, and a call for discovery

Atherosclerosis originates in childhood and adolescence. The goal of this review is to highlight how exercise and physical activity during childhood and adolescence, critical periods of growth and development, can prevent adult cardiovascular disease (CVD), particularly through molecular mechanisms of monocytes, a key cell of the innate immune system. Monocytes are heterogeneous and pluripotential cells that can, paradoxically, play a role in both the instigation and prevention of atherosclerosis. Recent discoveries in young adults reveal that brief exercise affects monocyte gene pathways promoting a cell phenotype that patrols the vascular system and repairs injuries. Concurrently, exercise inhibits pro-inflammatory monocytes, cells that contribute to vascular damage and plaque formation. Because CVD is typically asymptomatic in youth, minimally invasive techniques must be honed to study the subtle anatomic and physiologic evidence of vascular dysfunction. Exercise gas exchange and heart rate measures can be combined with ultrasound assessments of vascular anatomy and reactivity, and near-infrared spectroscopy to quantify impaired O₂ transport that is often hidden at rest. Combined with functional, transcriptomic, and epigenetic monocyte expression and measures of monocyte-endothelium interaction, molecular mechanisms of early CVD can be formulated, and then translated into effective physical activity-based strategies in youth to prevent adult-onset CVD.

Macrophages and T cells in atherosclerosis: a translational perspective

Atherosclerosis is now considered a chronic maladaptive inflammatory disease. The hallmark feature in both human and murine disease is atherosclerotic plaques. Macrophages and various T-cell lineages play a crucial role in atherosclerotic plaque establishment and disease progression. Humans and mice share many of the same processes that occur within atherogenesis. The various similarities enable considerable insight into disease mechanisms and those which contribute to cardiovascular complications. The apolipoprotein E-null and low-density lipoprotein receptor-null mice have served as the foundation for further immunological pathway manipulation to identify pro- and antiatherogenic pathways in attempt to reveal more novel therapeutic targets. In this review, we provide a translational perspective and discuss the roles of macrophages and various T-cell lineages in contrasting proatherosclerotic and atheroprotective settings.

The role of pro-inflammatory cytokines in lipid metabolism of metabolic diseases

Adipose tissue has been considered as a crucial source of certain pro-inflammatory cytokines; conversely, these pro-inflammatory cytokines are involved in regulating the proliferation and apoptosis of adipocytes, promoting lipolysis, inhibiting lipid synthesis and decreasing blood lipids, etc. In recent decades, extensive studies have indicated that pro-inflammatory cytokines play important roles in the development of lipid metabolism of metabolic diseases, including obesity, atherosclerosis, steatohepatitis and hyperlipoproteinemia. However, the involved pro-inflammatory cytokines types and the underlying mechanisms remain largely unknown. The "re-discovery" of cancer as a metabolic disorder largely occurred in the last five years. Although pro-inflammatory cytokines have been intensively investigated in cancer research, there are very few studies about the roles of pro-inflammatory cytokines in the lipid metabolism of cancer. In the current review, we provide an overview of the progress that has been made in the roles of different pro-inflammatory cytokines in lipid metabolism of metabolic diseases including cancer.

Treatment with 3,4-dihydroxyphenylethyl alcohol glycoside ameliorates sepsis-induced ALI in mice by reducing inflammation and regulating M1 polarization

The bioactive phenylethanoid 3,4-dihydroxyphenylethyl alcohol glycoside (DAG) is a component isolated from Sargentodoxa cuneata. The effects of DAG on acute lung injury (ALI) are largely unknown. Here, the effects of DAG on sepsis-induced ALI were investigated, and the related mechanisms were explored. Male C57BL/6 mice were used to establish a sepsis-induced ALI model. Levels of inflammatory cytokines were determined using real-time quantitative reverse transcription PCRs (qRT-PCR) and enzyme-linked immunosorbent assays (ELISAs). Pathological changes in the lung tissues were evaluated using haematoxylin and eosin (HE) staining. Mouse survival was quantified, and macrophage polarization was analyzed using flow cytometry. Our results showed that, in septic mice, pretreatment with DAG significantly improved survival, reduced histological damage in the lung, and suppressed the inflammatory response by inhibiting the activation of the NF-κB, STAT3, and p38 MAPK signaling pathways. Moreover, DAG treatment reduced the percentage of M1 macrophages in the bronchoalveolar lavage fluid (BALF) and spleen. In addition, DAG treatment decreased the production of pro-inflammatory cytokines and suppressed the activation of the NF-κB, STAT3, and p38 MAPK signaling pathways in LPS-induced MH-S cells. DAG treatment also reduced the relative abundances of M1 macrophages and M1 macrophage markers by suppressing the activation of the Notch1 signaling pathway. Thus, our results provided new insights for the development of drugs to treat ALI.

Notch Signaling Regulates Immune Responses in Atherosclerosis

Atherosclerosis is a chronic autoimmune inflammatory disease that can cause coronary artery disease, stroke, peripheral artery disease, depending on which arteries are affected. At the beginning of atherosclerosis plasma lipoproteins accumulate in the sub-endothelial space. In response, monocytes migrate from the circulation through the endothelium into the intima where they differentiate into macrophages. These early events trigger a complex immune response that eventually involves many cellular subtypes of both innate and adaptive immunity. The Notch signaling pathway is an evolutionary conserved cell signaling system that mediates cell-to-cell communication. Recent studies have revealed that Notch modulate atherosclerosis by controlling macrophages polarization into M1 or M2 subtypes. Furthermore, it is known that Notch signaling controls differentiation and activity of T-helper and cytotoxic T-cells in inflammatory diseases. In this review, we will discuss the role of Notch in modulating immunity in the context of atherosclerosis and whether targeting Notch may represent a therapeutic strategy.

Rapamycin and FTY720 Alleviate Atherosclerosis by Cross Talk of Macrophage Polarization and Autophagy

Foam cell formation and macrophage polarization are involved in the pathologic development of atherosclerosis, one of the most important human diseases affecting large and medium artery walls. This study was designed to assess the effects of rapamycin and FTY720 (fingolimod) on macrophages and foam cells. Mouse peritoneal macrophages were collected and treated with rapamycin and FTY720 to study autophagy, polarization, and lipid accumulation. Next, foam cells were formed by oxidizing low-density lipoprotein to observe changes in lipid accumulation, autophagy, and polarization in rapamycin-treated or FTY720-treated foam cells. Lastly, foam cells that had been treated with rapamycin and FTY720 were evaluated for sphingosine 1-phosphate receptor (S1prs) expression. Autophagy microtubule-associated protein 1 light chain 3- (LC3-) II was increased, and classically activated macrophage phenotype markers interleukin- (IL-) 6, cyclooxygenase-2 (COX2), and inducible nitric oxide synthase (iNOS) were increased, whereas alternatively activated macrophage phenotype markers transforming growth factor- (TGF-) β, arginase 1 (Arg1), and mannose receptor C-type 1 (Mrc1) were decreased by rapamycin in peritoneal macrophages. LC3-II was also obviously enhanced, though polarization markers were unchanged in rapamycin-treated foam cells. Moreover, lipid accumulation was inhibited in rapamycin-treated macrophage cells but was unchanged in rapamycin-treated foam cells. For FTY720, LC3-II did not change, whereas TGF-β, Arg1 and Mrc1 were augmented, and IL-6 was suppressed in macrophages. However, LC3-II was increased, and TGF-β, ARG1 and MRC1 were strikingly augmented, whereas IL-6, COX2 and iNOS could be suppressed in foam cells. Furthermore, lipid accumulation was alleviated in FTY720-treated foam cells. Additionally, S1pr1 was markedly decreased in foam cells (P < .05); S1pr2, S1pr3, S1pr4 and S1pr5 were unchanged in rapamycin-treated foam cells. In FTY720-treated foam cells, S1pr3 and S1pr4 were decreased, and S1pr1, S1pr2 and S1pr5 were unchanged. Therefore, we deduced that rapamycin stimulated classically activated macrophages and supressed early atherosclerosis. Rapamycin may also stabilize artery plaques by preventing apoptosis and S1PR1 in advanced atherosclerosis. FTY720 allowed transformation of foam cells into alternatively activated macrophages through the autophagy pathway to alleviate advanced atherosclerosis.

SM22α (Smooth Muscle Protein 22-α) Promoter-Driven IGF1R (Insulin-Like Growth Factor 1 Receptor) Deficiency Promotes Atherosclerosis

Objective- IGF-1 (insulin-like growth factor 1) is a major autocrine/paracrine growth factor, which promotes cell proliferation, migration, and survival. We have shown previously that IGF-1 reduced atherosclerosis and promoted features of stable atherosclerotic plaque in Apoe-/- mice-an animal model of atherosclerosis. The aim of this study was to assess effects of smooth muscle cell (SMC) IGF-1 signaling on the atherosclerotic plaque. Approach and Results- We generated Apoe-/- mice with IGF1R (IGF-1 receptor) deficiency in SMC and fibroblasts (SM22α [smooth muscle protein 22 α]-CreKI/IGF1R-flox mice). IGF1R was decreased in the aorta and adventitia of SM22α-CreKI/IGF1R-flox mice and also in aortic SMC, embryonic, skin, and lung fibroblasts isolated from SM22α-CreKI/IGF1R-flox mice. IGF1R deficiency downregulated collagen mRNA-binding protein LARP6 (La ribonucleoprotein domain family, member 6) and vascular collagen, and mice exhibited growth retardation. The high-fat diet-fed SM22α-CreKI/IGF1R-flox mice had increased atherosclerotic burden and inflammatory responses. α-SMA (α-smooth muscle actin)-positive plaque cells had reduced proliferation and elevated apoptosis. SMC/fibroblast-targeted decline in IGF-1 signaling decreased atherosclerotic plaque SMC, markedly depleted collagen, reduced plaque fibrous cap, and increased plaque necrotic cores. Aortic SMC isolated from SM22α-CreKI/IGF1R-flox mice had decreased cell proliferation, migration, increased sensitivity to apoptosis, and these effects were associated with disruption of IGF-1-induced Akt signaling. Conclusions- IGF-1 signaling in SMC and in fibroblast is a critical determinant of normal vascular wall development and atheroprotection.

Interleukin-1β has atheroprotective effects in advanced atherosclerotic lesions of mice

Despite decades of research, our understanding of the processes controlling late-stage atherosclerotic plaque stability remains poor. Although a prevailing hypothesis is that reducing inflammation may improve advanced plaque stability, direct evidence of this is lacking. Therefore, we performed intervention studies on smooth muscle cell (SMC) lineage tracing Apoe^−/− mice with advanced atherosclerosis using anti-IL-1β or IgG control antibodies. Surprisingly, we found that IL-1β antibody treatment between 18 and 26 weeks of Western diet feeding induced a marked reduction in SMC and collagen content, but increased macrophage number in the fibrous cap. There was also no change in lesion size and complete inhibition of beneficial outward remodeling. We also found that SMC-specific Il1r1 KO resulted in smaller lesions nearly devoid of SMC and a fibrous cap whereas macrophage-selective loss of IL-1R1 had no effect on lesion size or composition. Taken together, results show that IL-1β promotes multiple beneficial changes in late-stage murine atherosclerosis including promoting outward remodeling and formation and maintenance of a SMC/collagen-rich fibrous cap.

Small molecule disruption of G protein βγ subunit signaling reprograms human macrophage phenotype and prevents autoimmune myocarditis in rats

The purpose of this study was to determine whether blocking of G protein βγ (Gβγ) signaling halts heart failure (HF) progression by macrophage phenotype manipulation. Cardiac Gβγ signaling plays a crucial role in HF pathogenesis. Previous data suggested that inhibiting Gβγ signaling reprograms T helper cell 1 (Th1) and Th2 cytokines, suggesting that Gβγ might be a useful drug target for treating HF. We investigated the efficacy of a small molecule Gβγ inhibitor, gallein, in a clinically relevant, experimental autoimmune myocarditis (EAM) model of HF as well as in human macrophage phenotypes in vitro. In the myocardium of HF patients, we observed that G protein coupled receptor kinase (GRK)2 levels were down-regulated compared with healthy controls. In rat EAM, treatment with gallein effectively improved survival and cardiac function, suppressed cardiac remodeling, and further attenuated myocardial protein expression of GRK2 as well as high mobility group box (HMGB)1 and its cascade signaling proteins. Furthermore, gallein effectively inhibited M1 polarization and promoted M2 polarization in vivo in the EAM heart and in vitro in human monocyte-derived macrophages. Taken together, these data suggest that the small molecule Gβγ inhibitor, gallein, could be an important pharmacologic therapy for HF as it can switch the phenotypic reprogramming from M1 to M2 phenotype in a rat model of EAM heart and in human macrophages.

Follistatin-Like Protein-1 Upregulates Dendritic Cell-Based Immunity in Patients with Nasopharyngeal Carcinoma

Follistatin-like protein-1 (FSTL1) is an inflammatory factor that can induce an inflammatory response and is expressed in cancers. However, little is known about its content and function in nasopharyngeal carcinoma (NPC). Interleukin (IL)-12 and IL-4 are primarily secreted by dendritic cells (DCs) and activated T lymphocytes, respectively; these factors can induce Th cell differentiation and cytotoxic lymphocyte production, both of which facilitate tumors through the STAT4 and STAT6 pathways, respectively. In this study, the relationship between FSTL1 and both IL-12 and IL-4 as well as the functional mechanism of these cytokines was explored. Enzyme-linked immunosorbent assay, flow cytometry, and Western blotting were used to assess the levels of key inflammatory factors and DC markers as well as elucidate the mechanism by which FSTL-1 mediates and exerts it antitumor effects. The results revealed that serum FSTL1 and IL-12 levels were significantly decreased in NPC patients compared with those in the control group (P < 0.05); conversely, IL-4 levels were increased (P < 0.05). Supernatants from the experimental groups (EGs) contained higher IL-4 and IL-12 levels than those from the control groups (P < 0.05). Additionally, phosphorylated-STAT6 and phosphorylated-STAT4 were increased in the EGs (P < 0.05). These results suggest that DC-mediated immunity was activated by FSTL1, which leads to an increase of IL-12 and IL-4 production and consequently activates the STAT4 and STAT6 pathways through upregulation of STAT4 and STAT6 phosphorylation, respectively.

Inflammation: A Novel Therapeutic Target/Direction in Atherosclerosis

Over the past two decades, the viewpoint of atherosclerosis has been replaced gradually by a lipid-driven, chronic, low-grade inflammatory disease of the arterial wall. Current treatment of atherosclerosis is focused on limiting its risk factors, such as hyperlipidemia or hypertension. However, treatment targeting the inflammatory nature of atherosclerosis is still very limited and deserves further attention to fight atherosclerosis successfully. Here, we review the current development of inflammation and atherosclerosis to discuss novel insights and potential targets in atherosclerosis, and to address drug discovery based on anti-inflammatory strategy in atherosclerotic disease.

Suppressive effects of berberine on atherosclerosis via downregulating visfatin expression and attenuating visfatin-induced endothelial dysfunction

Berberine (BBR) possesses significant anti-atherosclerosis properties. Visfatin is one of the most promising biomarkers of incoming atherosclerosis. However, research on the effect of BBR on regulating visfatin expression in atherogenesis remains largely unknown. In this study, we investigated the effects of BBR on visfatin expression and atherogenesis in apolipoprotein E knockout (ApoE-/-) mice. The effect of BBR on attenuating visfatin-induced endothelial dysfunction was also evaluated in cultured human umbilical vein endothelial cells (HUVECs). In vivo experiments showed that BBR treatment (5 mg/kg/day) significantly reduced the serum levels of visfatin, lipid, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), the protein expression of visfatin, p-p38 MAPK and p-c-Jun N-terminal kinase (JNK) in mice aorta and the distribution of visfatin in the atherosclerotic lesions in ApoE-/- mice fed with a Western diet. In addition, in vitro experiments indicated that visfatin (100 µg/l) significantly increased apoptosis, the contents of IL-6 and TNF-α, the protein levels of p-p38 MAPK, p-JNK and Bax in HUVECs, which were reversed by BBR administration (50 µmol/l). Our findings suggest that BBR significantly ameliorates Western diet-induced atherosclerosis in ApoE-/- mice via downregulating visfatin expression, which is related to the inhibition of p38 MAPK and JNK signaling pathways and subsequent suppression of visfatin-induced endothelial dysfunction.

The Pivotal Role of Thymus in Atherosclerosis Mediated by Immune and Inflammatory Response

Atherosclerosis is one kind of chronic inflammatory disease, in which multiple types of immune cells or factors are involved. Data from experimental and clinical studies on atherosclerosis have confirmed the key roles of immune cells and inflammation in such process. The thymus as a key organ in T lymphocyte ontogenesis has an important role in optimizing immune system function throughout the life, and dysfunction of thymus has been proved to be associated with severity of atherosclerosis. Based on previous research, we begin with the hypothesis that low density lipoprotein or cholesterol reduces the expression of the thymus transcription factor Foxn1 via low density lipoprotein receptors on the membrane surface and low density lipoprotein receptor related proteins on the cell surface, which cause the thymus function decline or degradation. The imbalance of T cell subgroups and the decrease of naive T cells due to thymus dysfunction cause the increase or decrease in the secretion of various inflammatory factors, which in turn aggravates or inhibits atherosclerosis progression and cardiovascular events. Hence, thymus may be the pivotal role in coronary heart disease mediated by atherosclerosis and cardiovascular events and it can imply a novel treatment strategy for the clinical management of patients with atherosclerosis in addition to different commercial drugs. Modulation of immune system by inducing thymus function may be a therapeutic approach for the prevention of atherosclerosis. Purpose of this review is to summarize and discuss the recent advances about the impact of thymus function on atherosclerosis by the data from animal or human studies and the potential mechanisms.

STAT6 Upregulation Promotes M2 Macrophage Polarization to Suppress Atherosclerosis

Background

Macrophages are highly heterogeneous and plastic cells that are involved in all stages of atherogenesis. They can undergo polarization by shifting between M1 and M2 functional phenotypes. However, the role of macrophage polarization and the molecular mechanism in modulating atherosclerotic plaque stability remain incompletely understood. Our study investigated the role of STAT6 in regulating macrophage phenotypes to affect atherosclerotic plaque stability.

Material/Methods

A murine atherosclerosis model with vulnerable plaques was induced with high-cholesterol diet and PCCP surgeries in ApoE^−/− mice. Murine macrophages RAW264.7 treated with ox-LDL or IL-4 were used to simulate the in vitro process. pcDNA3.1(−)/STAT6-expressing vectors were transfected into RAW264.7 to evaluate its effect on cell polarization and the involved molecules.

Results

Unstable plaques presented significantly increased M1 markers (CD86 and iNOS) and less M2 markers (Arg-1 and TGF-β) than the stable plaques. Moreover, we found that STAT6 and p-STAT6 were greatly decreased in the vulnerable plaques and ox-LDL-induced macrophages, while their expression was elevated after IL-4 stimulation. The overexpression of STAT6 substantially reversed the ox-LDL-stimulated macrophage apoptosis and lipid accumulation. STAT6 upregulation promoted the differentiation of macrophage to M2 subtype as reflected by the increased expression of Arg-1 and TGF-β. Furthermore, we found that STAT6 overexpression activated the Wnt-β-catenin signaling by enhancing the translocation of β-catenin, while β-catenin suppression inhibited STAT6 overexpression-induced M2 polarization.

Conclusions

STAT6 facilitated atherosclerotic plaque stabilization by promoting the polarization of macrophages to M2 subtype and antagonizing ox-LDL-induced cell apoptosis and lipid deposition in a Wnt-β-catenin-dependent manner.

Ubiquitylation of MFHAS1 by the ubiquitin ligase praja2 promotes M1 macrophage polarization by activating JNK and p38 pathways

Sepsis is a systemic inflammation caused by infection. The balance between M1–M2 macrophage polarization has an essential role in the pathogenesis of sepsis. However, the exact mechanism underlying macrophage polarization is unclear. We previously showed that levels of malignant fibrous histiocytoma amplified sequence 1 (MFHAS1) were significantly elevated in septic patients compared with those in nonseptic patients, and involved in the activation of Toll-like receptor (TLR) 2/c-Jun N-terminal kinase (JNK)/nuclear factor (NF)-κB pathway. In the present study, we explored whether MFHAS1 was involved in macrophage polarization and determined the effect of MFHAS1 on inflammation. We performed in vitro pulldown assays and in vivo co-immunoprecipitation assays and found that E3 ubiquitin ligase praja2 could directly bind to MFHAS1. In situ immunostaining analysis confirmed the colocalization of endogenous praja2 with MFHAS1. We first reported that praja2 promotes the accumulation of ubiquitylated MFHAS1 but does not degrade it. Moreover, our results indicate that MFHAS1 ubiquitylation by praja2 positively regulates TLR2-mediated JNK/p38 pathway and promotes M1 macrophage polarization, M2 to M1 macrophage transformation and inflammation.

Mesenchymal stem cell-derived extracellular vesicles attenuate kidney inflammation

Mesenchymal stem/stromal cells (MSCs) have distinct capability for renal repair, but may have safety concerns. MSC-derived extracellular vesicles emerged as a novel noncellular alternative. Using a porcine model of metabolic syndrome and renal artery stenosis we tested whether extracellular vesicles attenuate renal inflammation, and if this capacity is mediated by their cargo of the anti-inflammatory cytokine interleukin (IL) 10. Pigs with metabolic syndrome were studied after 16 weeks of renal artery stenosis untreated or treated four weeks earlier with a single intrarenal delivery of extracellular vesicles harvested from adipose tissue-derived autologous MSCs. Lean and sham metabolic syndrome animals served as controls (seven each). Five additional pigs with metabolic syndrome and renal artery stenosis received extracellular vesicles with pre-silenced IL10 (IL10 knock-down). Single-kidney renal blood flow, glomerular filtration rate, and oxygenation were studied in vivo and renal injury pathways ex vivo. Retention of extracellular vesicles in the stenotic kidney peaked two days after delivery and decreased thereafter. Four weeks after injection, extracellular vesicle fragments colocalized with stenotic-kidney tubular cells and macrophages, indicating internalization or fusion. Extracellular vesicle delivery attenuated renal inflammation, and improved medullary oxygenation and fibrosis. Renal blood flow and glomerular filtration rate fell in metabolic syndrome and renal artery stenosis compared to metabolic syndrome, but was restored in pigs treated with extracellular vesicles. These renoprotective effects were blunted in pigs treated with IL10-depleted extracellular vesicles. Thus, extracellular vesicle-based regenerative strategies might be useful for patients with metabolic syndrome and renal artery stenosis.