Interleukin-18 predicts atherosclerosis progression in SIV-infected and uninfected rhesus monkeys (Macaca mulatta) on a high-fat/high-cholesterol diet

Simian immunodeficiency virus-infected rhesus macaques with AIDS co-develop cardiovascular pathology and encephalitis

Despite effective antiretroviral therapy, HIV co-morbidities remain where central nervous system (CNS) neurocognitive disorders and cardiovascular disease (CVD)-pathology that are linked with myeloid activation are most prevalent. Comorbidities such as neurocogntive dysfunction and cardiovascular disease (CVD) remain prevalent among people living with HIV. We sought to investigate if cardiac pathology (inflammation, fibrosis, cardiomyocyte damage) and CNS pathology (encephalitis) develop together during simian immunodeficiency virus (SIV) infection and if their co-development is linked with monocyte/macrophage activation. We used a cohort of SIV-infected rhesus macaques with rapid AIDS and demonstrated that SIV encephalitis (SIVE) and CVD pathology occur together more frequently than SIVE or CVD pathology alone. Their co-development correlated more strongly with activated myeloid cells, increased numbers of CD14+CD16+ monocytes, plasma CD163 and interleukin-18 (IL-18) than did SIVE or CVD pathology alone, or no pathology. Animals with both SIVE and CVD pathology had greater numbers of cardiac macrophages and increased collagen and monocyte/macrophage accumulation, which were better correlates of CVD-pathology than SIV-RNA. Animals with SIVE alone had higher levels of activated macrophage biomarkers and cardiac macrophage accumulation than SIVnoE animals. These observations were confirmed in HIV infected individuals with HIV encephalitis (HIVE) that had greater numbers of cardiac macrophages and fibrosis than HIV-infected controls without HIVE. These results underscore the notion that CNS and CVD pathologies frequently occur together in HIV and SIV infection, and demonstrate an unmet need for adjunctive therapies targeting macrophages.

Deficiency of Caspase-1 Attenuates HIV-1-Associated Atherogenesis in Mice

Within arterial plaque, HIV infection creates a state of inflammation and immune activation, triggering NLRP3/caspase-1 inflammasome, tissue damage, and monocyte/macrophage infiltration. Previously, we documented that caspase-1 activation in myeloid cells was linked with HIV-associated atherosclerosis in mice and people with HIV. Here, we mechanistically examined the direct effect of caspase-1 on HIV-associated atherosclerosis. Caspase-1-deficient (Casp-1-/-) mice were crossed with HIV-1 transgenic (Tg26+/-) mice with an atherogenic ApoE-deficient (ApoE-/-) background to create global caspase-1-deficient mice (Tg26+/-/ApoE-/-/Casp-1-/-). Caspase-1-sufficient (Tg26+/-/ApoE-/-/Casp-1+/+) mice served as the controls. Next, we created chimeric hematopoietic cell-deficient mice by reconstituting irradiated ApoE-/- mice with bone marrow cells transplanted from Tg26+/-/ApoE-/-/Casp-1-/- (BMT Casp-1-/-) or Tg26+/-/ApoE-/-/Casp-1+/+ (BMT Casp-1+/+) mice. Global caspase-1 knockout in mice suppressed plaque deposition in the thoracic aorta, serum IL-18 levels, and ex vivo foam cell formation. The deficiency of caspase-1 in hematopoietic cells resulted in reduced atherosclerotic plaque burden in the whole aorta and aortic root, which was associated with reduced macrophage infiltration. Transcriptomic analyses of peripheral mononuclear cells and splenocytes indicated that caspase-1 deficiency inhibited caspase-1 pathway-related genes. These results document the critical atherogenic role of caspase-1 in chronic HIV infection and highlight the implication of this pathway and peripheral immune activation in HIV-associated atherosclerosis.

Non-linear optical imaging of atherosclerotic plaques in the context of SIV and HIV infection prominently detects crystalline cholesterol esters

Chronic HIV infection may exacerbate atherosclerotic vascular disease, which at advanced stages presents as necrotic plaques rich in crystalline cholesterol. Such lesions can catastrophically rupture precipitating myocardial infarct and stroke, now important causes of mortality in those living with HIV. However, in this population little is known about plaque structure relative to crystalline content and its chemical composition. Here, we first interrogated plaque crystal structure and composition in atherosclerotic SIV-infected macaques using non-linear optical microscopy. By stimulated Raman scattering and second harmonic generation approaches both amorphous and crystalline plaque lipid was detected and the crystal spectral profile indicated a cholesterol ester (CE) dominated composition. Versus controls, SIV⁺ samples had a greater number of cholesterol crystals (CCs), with the difference, in part, accounted for by crystals of a smaller length. Given the ester finding, we profiled HIV⁺ plaques and also observed a CE crystalline spectral signature. We further profiled plaques from Ldlr^-/- mice fed a high fat diet, and likewise, found CE-dominate crystals. Finally, macrophage exposure to CCs or AcLDL induced auto-fluorescent puncta that co-stained with the LC3B autophagy sensor. In aggregate, we show that atheromatous plaques from mice, macaques and humans, display necrotic cores dominated by esterified CCs, and that plaque macrophages may induce autophagic vesicle formation upon encountering CCs. These findings help inform our knowledge of plaque core lipid evolution and how the process may incite systemic inflammation.

NLRP3 Inflammasome Signaling as a Link Between HIV-1 Infection and Atherosclerotic Cardiovascular Disease

36.9 million people worldwide are living with HIV-1. The disease remains incurable and HIV-infected patients have increased risk of atherosclerosis. Inflammation is a key driver of atherosclerosis, but no targeted molecular therapies have been developed to reduce cardiovascular risk in people with HIV-1 (PWH). While the mechanism is unknown, there are several important inflammatory signaling events that are implicated in the development of chronic inflammation in PWH and in the inflammatory changes that lead to atherosclerosis. Here we describe the pro-inflammatory state of HIV-1 infection that leads to increased risk of cardiovascular disease, the role of the NLR Family Pyrin Domain Containing 3 (NLRP3) inflammasome in HIV-1 infection, the role of the NLRP3 inflammasome in cardiovascular disease (CVD), and outline a model whereby HIV-1 infection can lead to atherosclerotic disease through NLRP3 inflammasome activation. Our discussion highlights the literature supporting HIV-1 infection as a stimulator of the NLRP3 inflammasome as a driver of atherosclerosis.

Interleukin-8 in Hyperlipidemia and Coronary Heart Disease in Thai Patients Taking Statin Cholesterol-Lowering Medication While Undergoing Coronary Artery Bypass Grafting Treatment

The role of interleukin-8 (IL-8), a pivotal chemokine in atherogenesis and coronary heart disease (CHD) development, is diverse and remains unclear. This cross-sectional study investigates the association of the IL-8 expression in hyperlipidemia (H) and CHD patients who have been treated with statin cholesterol-lowering drugs while undergoing coronary artery bypass grafting treatment. Fifty-five Thai volunteers including 13 normal (N), 24 H, and 18 CHD patients were enrolled for the investigation. All the CHD patients had been treated continuously with statin cholesterol-lowering medications since the disease was diagnosed and were undergoing coronary bypass grafting approximately one month later. Therefore, the CHD group was representative of a pathogenesis improvement in CHD. The IL8 mRNA expression was determined by real-time quantitative PCR in the peripheral blood mononuclear cells from heparinized blood. The plasma IL-8 levels were assessed by enzyme-linked immunosorbent assay. The result shows that the IL8 mRNA expression in the H group tended to increase; however, in the CHD group, there was a significant decrease (p=0.0111) compared to the N group. The IL8 mRNA expression and the plasma levels in the CHD group were significantly lower than those in the H group (p < 0.05). A significant negative correlation between the IL8 mRNA (r = -0.499) or plasma IL-8 (r = -0.3875) expression and CHD progression was observed (p < 0.05). In conclusion, the transcriptomic and the phenotypic IL-8 expression decreased significantly in the Thai CHD patients who had continuously received statin-group medications compared to the H and N group participants. Therefore, IL-8 should serve as a feasible marker and could be used to evaluate the therapeutic effects of statins and illustrate the pathology of CHD treatment.

Caspase-1-associated immune activation in an accelerated SIV-infected rhesus macaque model

In the antiretroviral therapy (ART) era, chronic HIV infection is primarily associated with chronic inflammation driving comorbidities such as cardiovascular disease and neurocognitive impairment. Caspase-1 activation in leukocytes has been documented in HIV infection; however, whether caspase-1 activation and the downstream pro-inflammatory cytokines interleukin-1beta (IL-1β) and interleukin-18 (IL-18) contribute to chronic inflammation in HIV comorbidities remains undetermined. The relationship between the caspase-1 cascade and persistent inflammation in HIV has not been investigated. Here, we used an accelerated simian immunodeficiency virus (SIV)-infected rhesus macaque model with or without ART to investigate the dynamics of caspase-1 and immune cell activation before infection, 21 days post infection (dpi), and necropsy. Caspase-1, IL-18, IL-1β, and immune markers were measured both in the circulation and lymphoid tissues. We found a significant increase in caspase-1 and IL-18 in SIV infection that positively correlated with inflammatory monocytes and negatively correlated with CD4⁺ T cell counts. ART attenuated these effects at necropsy in the circulation. Further, lymph nodes from SIV+ or SIV+ART animals had increased activation of caspase-1 and potential upstream priming of the NF-κB pathway, indicating that tissue-specific immune activation persists with ART. Together, these results shed light on the interconnectedness of the caspase-1 pathway and peripheral immune activation and further indicate that ART is not sufficient for suppressing inflammation. The caspase-1 pathway may provide novel therapeutic targets to improve HIV-associated comorbidities and health outcomes in the context of viral suppression.

NACHT, LRR and PYD domains-containing protein 3 inflammasome is activated and inhibited by berberine via toll-like receptor 4/myeloid differentiation primary response gene 88/nuclear factor-κB pathway, in phorbol 12-myristate 13-acetate-induced macrophages

The nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP-3) inflammasome has recently emerged as a pivotal regulator of chronic inflammation. The present study investigated the expression of NLRP3 inflammasome in phorbol 12-myristate 13-acetate (PMA)-induced macrophages, and aimed to identify the effects of berberine on the inflammasome. Human monocytic THP-1 cells were pretreated with berberine for 1 h and then induced with PMA for 48 h. Total RNA and protein were collected for reverse transcription-quantitative polymerase chain reaction and western blot analysis, respectively. Supernatants were collected to determine IL-1β levels by using ELISA. The present study demonstrated that NLRP3 inflammasome and IL-1β were activated in PMA-induced macrophages in a time-dependent manner, whereas berberine significantly inhibited their expression in a dose-dependent manner in PMA-induced macrophages. Furthermore, berberine also suppressed the toll-like receptor 4 (TLR4)/myeloid differentiation primary response gene 88 (Myd88)/nuclear factor (NF)-κB signaling pathway which was activated during the conversion of THP-1 cells to macrophages by PMA. In conclusion, berberine reduced NLRP3 inflammasone expression by suppressing the activation of the TLR4/Myd88/NF-κB signaling pathway in PMA-induced macrophages. This inhibitory effect may imply an important role of berberine on chronic inflammation and atherogenic progression in coronary artery disease.

HIV-1-Associated Atherosclerosis: Unraveling the Missing Link

Cardiovascular disease, including atherosclerosis and atherosclerosis-associated complications, is an increasing cause of morbidity and mortality in human immunodeficiency virus (HIV) patients in the post-antiretroviral therapy era. HIV alone accelerates atherosclerosis. Antiretroviral therapy; HIV-associated comorbidities, such as dyslipidemia, drug abuse, and opportunistic infections; and lifestyle are risk factors for HIV-associated atherosclerosis. However, our current understanding of HIV-associated atherogenesis is very limited and has largely been obtained from clinical observation. There is a pressing need to experimentally unravel the missing link between HIV and atherosclerosis. Understanding these mechanisms will help to better develop and design novel therapeutic interventions for the treatment of HIV-associated cardiovascular disease. HIV mainly infects T cells and macrophages resulting in the induction of oxidative and endoplasmic reticulum stress, the formation of the inflammasome, and the dysregulation of autophagy. These mechanisms may contribute to HIV-associated atherogenesis. In this review, we will summarize our current understanding and propose potential mechanisms of HIV-associated atherosclerosis.

Systemic Elevation of Proinflammatory Interleukin 18 in HIV/HCV Coinfection versus HIV or HCV Monoinfection

BACKGROUND

HIV/HCV coinfection and elevated interleukin (IL)-18 levels are both associated with enhanced progression of hepatic inflammation and increased risk of diabetes, kidney disease, and cardiovascular disease. IL-18 is a proinflammatory cytokine made upon activation of the inflammasome, an innate sensing system. We assessed whether increased IL-18 could explain the increased incidence and progression of inflammatory conditions seen with HIV/HCV coinfection.

METHODS

Serum from 559 subjects with HIV monoinfection, HCV monoinfection, HIV/HCV coinfection, or people who inject drugs with neither infection was tested for IL-18 by ELISA and for 16 other analytes by electrochemiluminescence immunoassay. IL-18 levels were measured in 14 additional chronically HCV infected subjects who developed incident HIV infection to determine if IL-18 increases with coinfection.

RESULTS

IL-18 was significantly elevated in coinfected individuals versus both monoinfections (p<0.0001) independent of age, sex, and race. IL-18 levels were significantly higher in HIV monoinfection than in HCV monoinfection. High IL-18 levels were correlated with detectable HIV viremia and inversely with CD4 count (p<0.0001), consistent with HIV activation of the inflammasome resulting in CD4 T cell depletion. Incident HIV infection of chronically HCV infected subjects resulted in increased IL-18 (p<0.001), while HIV suppression was associated with normal IL-18 levels. Four additional analytes (IP-10, IL-12/23p40, IFNy, IL-15) were found to be elevated in HIV/HCV coinfection when compared to both monoinfections.

CONCLUSIONS

HIV/HCV coinfection results in significantly elevated serum IL-18. The elevated levels of this proinflammatory cytokine may explain the increased incidence and progression of inflammatory illnesses seen in coinfected individuals.

Differential synthesis and release of IL-18 and IL-18 Binding Protein from human platelets and their implications for HIV infection

IL-18 is a pro-inflammatory cytokine belonging to the IL-1 family and is produced in the body from macrophages, epithelial and dendritic cells, keratinocytes, adrenal cortex etc. The cytokine is produced as an inactive precursor that is cleaved inside cells into its mature form by activated caspase 1, which exists as an inactive precursor in human cells and requires assembly of an inflammasomes for its activation. We show here for the first time that human platelets contain transcripts for the IL-18 gene. They synthesize the cytokine de novo, process and release it upon activation. The activation also results in the assembly of an inflammasome and activation of caspase-1. Platelets also contain the IL-18 antagonist, the IL-18-Binding Protein (IL-18BP); however, it is not synthesized in them de novo, is present in pre-made form and is released irrespective of platelet activation. IL-18 and IL-18BP co-localize to α granules inside platelets and are secreted out with different kinetics. Platelet activation contributes to plasma concentrations in healthy individuals, as their plasma samples contain abundant IL-18, while their platelet-poor plasma samples contain very little amounts of the cytokine. The plasma and PPP samples from these donors, however, contain comparable amounts of IL-18BP. Unlike healthy individuals, the platelet-poor plasma from HIV-infected individuals contains significant amounts of IL-18. Our findings have important implications for viral infections and other human diseases that are accompanied by platelet activation.

Current topics in HIV pathogenesis, part 2: Inflammation drives a Warburg-like effect on the metabolism of HIV-infected subjects

HIV-1 infection leads to a depletion of CD4 T-cells associated with a persistent immune inflammation and changes in cellular metabolism. Most effort of managing HIV infection with combination of antiretroviral therapies (ART) has been focused on CD4 T-cell recovery, while control of persistent immune inflammation and metabolism were relatively underappreciated in the past. Recent discoveries on the interplay between innate immunity, inflammation (especially the inflammasome) and metabolic changes in the context of cancer and autoimmunity provide an emerging field for chronic viral infections including HIV-1. In a previous review, we described the deregulated metabolism contributing to immune dysfunctions such as alteration of memory T-cell responses, mucosal protection, and dendritic cell-related antigen presentation. Here, we summarize the latest knowledge on the detrimental influence of long-lasting inflammation and inflammasome activation induced by HIV-1, gut dysbiosis, and bacterial translocation, on metabolism during the course of viral infection. We also report on the inability of ART to fully counteract inflammation, resulting in partial metabolic improvement and leading to an insufficient decrease in the risk of non-AIDS events. Further advances in our understanding of the relationship between inflammation, altered metabolism, and long-term ART is warranted. Additionally, there is a critical need for developing new strategies to regulate the pro-inflammatory signals to enhance cellular metabolism and immune functions in order to improve the quality of life of individuals living with HIV-1.

Cellular and molecular mechanisms of statins: an update on pleiotropic effects

Coronary artery disease (CAD) is the leading cause of death worldwide. The efficacy and safety of statins (3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors) in primary and secondary prevention of CAD are confirmed in several large studies. It is well known that statins have some pleiotropic, anti-atherosclerotic effects. We review the molecular mechanisms underlying the beneficial effects of statins revealed in recently published studies. Endothelial cell injury is regarded as the classic stimulus for the development of atherosclerotic lesions. In addition, the inflammatory process plays an important role in the aetiology of atherosclerosis. In particular, chronic inflammation plays a key role in coronary artery plaque instability and subsequent occlusive thrombosis. Our previous reports and others have demonstrated beneficial effects of statins on endothelial dysfunction and chronic inflammation in CAD. A better understanding of the molecular mechanism underlying the effectiveness of statins against atherosclerosis may provide a novel therapeutic agent for the treatment of coronary atherosclerosis. The present review summarizes the cellular and molecular mechanism of statins against coronary atherosclerosis.

HIV and HCV activate the inflammasome in monocytes and macrophages via endosomal Toll-like receptors without induction of type 1 interferon

Innate immune sensing of viral infection results in type I interferon (IFN) production and inflammasome activation. Type I IFNs, primarily IFN-α and IFN-β, are produced by all cell types upon virus infection and promote an antiviral state in surrounding cells by inducing the expression of IFN-stimulated genes. Type I IFN production is mediated by Toll-like receptor (TLR) 3 in HCV infected hepatocytes. Type I IFNs are also produced by plasmacytoid dendritic cells (pDC) after sensing of HIV and HCV through TLR7 in the absence of productive pDC infection. Inflammasomes are multi-protein cytosolic complexes that integrate several pathogen-triggered signaling cascades ultimately leading to caspase-1 activation and generation pro-inflammatory cytokines including interleukin (IL)-18 and IL-1β. Here, we demonstrate that HIV and HCV activate the inflammasome, but not Type I IFN production, in monocytes and macrophages in an infection-independent process that requires clathrin-mediated endocytosis and recognition of the virus by distinct endosomal TLRs. Knockdown of each endosomal TLR in primary monocytes by RNA interference reveals that inflammasome activation in these cells results from HIV sensing by TLR8 and HCV recognition by TLR7. Despite its critical role in type I IFN production by pDCs stimulated with HIV, TLR7 is not required for inflammasome activation by HIV. Similarly, HCV activation of the inflammasome in monocytes does not require TLR3 or its downstream signaling adaptor TICAM-1, while this pathway leads to type I IFN in infected hepatocytes. Monocytes and macrophages do not produce type I IFN upon TLR8 or TLR7 sensing of HIV or HCV, respectively. These findings reveal a novel infection-independent mechanism for chronic viral induction of key anti-viral programs and demonstrate distinct TLR utilization by different cell types for activation of the type I IFN vs. inflammasome pathways of inflammation.

Pathogens are detected by the immune system in multiple ways that initiate responses to control infection. Two systems of first line defense against viruses are 1) the production of Type I interferons and 2) production of the cytokines IL-1β and IL-18 by the inflammasome. Type I interferons promote an antiviral state in the infected host. Inflammasome cytokines induce inflammation, modulate adaptive immune responses, and have direct antiviral effects. While both are produced in response to the chronic human viral infections HIV and HCV, we demonstrate here that inflammasome activation does not require cell infection and that the mechanisms for viral sensing as well as cell types in which sensing occurs are distinct between the two viruses and between the type I interferon vs. inflammasome systems. The relative amount of sensing via these different mechanisms may affect the balance between antiviral and inflammatory responses to chronic infection.

SIV vpx is essential for macrophage infection but not for development of AIDS

Analysis of rhesus macaques infected with a vpx deletion mutant virus of simian immunodeficiency virus mac239 (SIVΔvpx) demonstrates that Vpx is essential for efficient monocyte/macrophage infection in vivo but is not necessary for development of AIDS. To compare myeloid-lineage cell infection in monkeys infected with SIVΔvpx compared to SIVmac239, we analyzed lymphoid and gastrointestinal tissues from SIVΔvpx-infected rhesus (n = 5), SIVmac239-infected rhesus with SIV encephalitis (7 SIV239E), those without encephalitis (4 SIV239noE), and other SIV mutant viruses with low viral loads (4 SIVΔnef, 2 SIVΔ3). SIV+ macrophages and the percentage of total SIV+ cells that were macrophages in spleen and lymph nodes were significantly lower in rhesus infected with SIVΔvpx (2.2%) compared to those infected with SIV239E (22.7%), SIV239noE (8.2%), and SIV mutant viruses (10.1%). In colon, SIVΔvpx monkeys had fewer SIV+ cells, no SIV+ macrophages, and lower percentage of SIV+ cells that were macrophages than the other 3 groups. Only 2 SIVΔvpx monkeys exhibited detectable virus in the colon. We demonstrate that Vpx is essential for efficient macrophage infection in vivo and that simian AIDS and death can occur in the absence of detectable macrophage infection.

Adenosine 5'-monophosphate ameliorates D-galactosamine/lipopolysaccharide-induced liver injury through an adenosine receptor-independent mechanism in mice

D-galactosamine (GalN)/lipopolysaccharide (LPS)-induced lethality and acute liver failure is dependent on endogenously produced inflammatory cytokines. Adenosine has been proven to be a central role in the regulation of inflammatory response. It is not entirely clear that which adenosine action is actually crucial to limiting inflammatory tissue destruction. Here we showed that GalN/LPS challenge elevated hepatic adenosine and induced lethality in adenosine receptor-deficient mice with equal efficiency as wild-type mice. In GalN/LPS-treated mice, pretreatment with adenosine 5'-monophosphate (5'-AMP) significantly elevated hepatic adenosine level and reduced mortality through decreasing cytokine and chemokine production. In RAW264.7 cells, 5'-AMP treatment inhibited the production of inflammatory cytokines, which is not mediated through adenosine receptors. 5'-AMP failed to attenuate LPS-induced nuclear factor-κB (NF-κB) p65 nuclear translocation, but reduced LPS-induced recruitment of NF-κB p65 to inflammatory gene promoters and decreased LPS-induced enrichment of H3K4 dimethylation at the tumor necrosis factor-α (TNF-α) promoter, which was involved in 5'-AMP-induced elevation of cellular adenosine and a decline of methylation potential. In vitro biochemical analysis revealed that adenosine directly attenuated recruitment of NF-κB to the TNF-α and interleukin-6 promoters. Our findings demonstrate that 5'-AMP-inhibiting inflammatory response is not mediated by adenosine receptors and it may represent a potential protective agent for amelioration of LPS-induced liver injury.

NLRP3 inflammasome activation in coronary artery disease: results from prospective and randomized study of treatment with atorvastatin or rosuvastatin

The NLRP-3 (nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3) inflammasome has recently emerged as a pivotal regulator of chronic inflammation. The aim of the present study was to determine whether NLRP3 inflammasome is expressed in patients with CAD (coronary artery disease) and whether statins (atorvastatin or rosuvastatin) might affect NLRP3 levels. In an in vitro study, human THP-1 cells treated with statins were analysed for NLRP3 inflammasome levels. The present study included 60 patients with CAD and 30 subjects without CAD (non-CAD). Patients with CAD randomly received either 8 months of treatment with atorvastatin or rosuvastatin. PBMCs (peripheral blood mononuclear cells) were obtained from peripheral blood at baseline and after 8 months of statin therapy. Levels of NLRP3 inflammasome, IL (interleukin)-1β and IL-18 were measured by real-time RT–PCR (reverse transcription–PCR) and FACS. Levels of NLRP3 inflammasome were higher in the CAD group than in the non-CAD group. There was a positive correlation between NLRP3 inflammasome and cytokines (IL-1β and IL-18) levels. A randomized clinical study has shown that atorvastatin markedly diminished NLRP3 inflammasome levels, whereas rosuvastatin had no impact on these levels. Levels of NLRP3 inflammasome decreased in THP-1 cells treated with statins compared with those treated with vehicle, and the fold changes in NLRP3 inflammasome were higher in THP-1 cells treated with atorvastatin compared with those treated with rosuvastatin. The present study suggests that atorvastatin down-regulates NLRP3 inflammasome expression in CAD, possibly contributing to the inhibitory effects of atorvastatin on chronic inflammation and atherogenic progression in this disorder.

Interleukin-8 induces the endothelial cell migration through the activation of phosphoinositide 3-kinase-Rac1/RhoA pathway

Endothelial cell migration is essential for tumor angiogenesis, and interleukin-8 (IL-8) has been shown to play an important role in tumor growth, angiogenesis, and metastasis. This study aimed to investigate the molecular mechanism of IL-8 induced endothelial cell migration. Our results indicated that IL-8 induced a rapid rearrangement of the actin cytoskeleton in EA.Hy926 cells, generating extensions resembling membrane ruffling and stress fibers. These processes required parallel upregulation of the small GTPases Rac1 and RhoA. Moreover, we demonstrated that IL-8 activated PI3K following the same kinetics observed from IL-8 induction of cytoskeletal rearrangement, suggesting the participation of PI3K in these processes. Taken together, our study demonstrates that PI3K-Rac1/RhoA signaling pathway plays a vital role in IL-8 induced endothelial cell migration, and provides new insight into the molecular mechanisms by which IL-8 contributes to tumor angiogenesis and metastasis.

Myocarditis in CD8-depleted SIV-infected rhesus macaques after short-term dual therapy with nucleoside and nucleotide reverse transcriptase inhibitors

BACKGROUND

Although highly active antiretroviral therapy (HAART) has dramatically reduced the morbidity and mortality associated with HIV infection, a number of antiretroviral toxicities have been described, including myocardial toxicity resulting from the use of nucleotide and nucleoside reverse transcriptase inhibitors (NRTIs). Current treatment guidelines recommend the use of HAART regimens containing two NRTIs for initial therapy of HIV-1 positive individuals; however, potential cardiotoxicity resulting from treatment with multiple NRTIs has not been addressed.

METHODOLOGY/PRINCIPAL FINDINGS

We examined myocardial tissue from twelve CD8 lymphocyte-depleted adult rhesus macaques, including eight animals infected with simian immunodeficiency virus, four of which received combined antiretroviral therapy (CART) consisting of two NRTIs [(9-R-2-Phosphonomethoxypropyl Adenine) (PMPA) and (+/-)-beta-2',3'-dideoxy-5-fluoro-3'-thiacytidine (RCV)] for 28 days. Multifocal infiltrates of mononuclear inflammatory cells were present in the myocardium of all macaques that received CART, but not untreated SIV-positive animals or SIV-negative controls. Macrophages were the predominant inflammatory cells within lesions, as shown by immunoreactivity for the macrophage markers Iba1 and CD68. Heart specimens from monkeys that received CART had significantly lower virus burdens than untreated animals (p<0.05), but significantly greater quantities of TNF-α mRNA than either SIV-positive untreated animals or uninfected controls (p<0.05). Interferon-γ (IFN-γ), IL-1β and CXCL11 mRNA were upregulated in heart tissue from SIV-positive monkeys, independent of antiretroviral treatment, but CXCL9 mRNA was only upregulated in heart tissue from macaques that received CART.

CONCLUSIONS/SIGNIFICANCE

These results suggest that short-term treatment with multiple NRTIs may be associated with myocarditis, and demonstrate that the CD8-depleted SIV-positive rhesus monkey is a useful model for studying the cardiotoxic effects of combined antiretroviral therapy in the setting of immunodeficiency virus infection.

Effect of Qingre Quyu Granule (清热祛瘀颗粒) on stabilizing plaques in the brachiocephalic artery of apolipoprotein E deficient mice

OBJECTIVE

To investigate the effect of Qingre Quyu Granule (清热祛瘀颗粒, QRQYG) on stabilizing vulnerable plaques in apolipoprotein E (ApoE) deficient mice.

METHODS

Seventy-two male ApoE deficient mice were given a high-fat diet from 6 weeks of age. At the 16th week, all the mice were randomized into 3 groups: the QRQYG group, the simvastatin group, and the control group. Sixteen weeks after administration of 0.9 g/kg QRQYG, 3 mg/kg simvastatin or 10 mg/kg sodium chloride per day to the respective groups, the animals were euthanized. The pathological morphologic changes in the vulnerable plaques were evaluated, the matrix metalloprotease-9 (MMP-9) expression was measured by immunohistofluorescence, the soluble intercellular adhesion molecule 1 (ICAM-1) was determined by ELISA, the nuclear factor kappaB (NF-κB) subunit p65 was measured by quantitative RT-PCR, and, finally, thrombospondin-1 (TSP-1) was determined by the immunohistochemical method.

RESULTS

The plaque cross-sectional area in the brachiocephalic artery (23.7%, P<0.01), the lipid core of the plaque (43.1%±3.1%), and the number of buried fibrotic caps of the plaque were significantly decreased in the QRQYG group compared to the control group (both P<0.01); furthermore, the thickness of the fibrotic cap of the plaque increased and the intra-plaque hemorrhage of the plaque decreased. The serum soluble ICAM-1 (27.1±5.1 μg/mL), the protein expression of MMP-9 and TSP-1 and the p65 mRNA expression increased in the QRQYG group in comparison with the control group (P<0.05 or P<0.01).

CONCLUSION

QRQYG could stabilize the vulnerable plaque through inhibition of the inflammatory response.

Circulating Nef induces dyslipidemia in simian immunodeficiency virus-infected macaques by suppressing cholesterol efflux

Human immunodeficiency virus (HIV) infection and subsequent antiretroviral therapy have been associated with an increased incidence of dyslipidemia and cardiovascular disease and has been shown to suppress cholesterol efflux from virus-infected macrophages by inducing Nef-dependent down-regulation of adenosine triphosphate-binding cassette transporter A1 (ABCA1). Here, the simian immunodeficiency virus (SIV)-infected macaque model was used to examine the consequences and mechanisms involved. SIV infection drove a significant remodeling of high-density lipoprotein profiles, suggesting that systemic inhibition of the ABCA1-dependent reverse cholesterol transport pathway occurred. The ABCA1 cholesterol transporter was significantly down-regulated in the livers of the SIV-infected macaques, and the viral protein Nef could be detected in the livers as well as in the plasma of infected animals. Extracellular myristoylated HIV Nef inhibited cholesterol efflux from macrophages and hepatocytes. Moreover, serum samples from SIV-infected macaques also suppressed cholesterol efflux in a Nef-dependent fashion. These results indicate that SIV infection is a significant contributor to primary dyslipidemia, likely through the ability of Nef to suppress ABCA1-dependent reverse cholesterol transport.

Expanded network of inflammatory markers of atherogenesis: where are we now?

Inflammatory biomarkers play a pivotal role in atherosclerotic lesions. The plasma levels of these markers are predictive of adverse outcomes such as myocardial infarction and cardiovascular death. The immune system is involved at all stages of atherogenesis via activation of monocytes/macrophages and T lymphocytes. Circulating proinflammatory cytokines and chemokines produced by these cells interact with specific receptors on various cells and activate specific signaling pathways, leading to inflammation-induced atherosclerotic lesions. Recent studies have focused on predictive value of inflammatory biomarkers such as C-reactive protein and interleukin-6. These biomarkers were shown to be associated with poor quality of life and predictive of adverse events in coronary atherosclerosis and left ventricular dysfunction. Vascular predictive value of other numerous inflammatory markers is being investigated. We herein analyze the role of several mediators of inflammation, affecting vascular functions and leading toward atherosclerotic lesions.

Expanded Network of Inflammatory Markers of Atherogenesis: Where Are We Now?

Inflammatory biomarkers play a pivotal role in atherosclerotic lesions. The plasma levels of these markers are predictive of adverse outcomes such as myocardial infarction and cardiovascular death. The immune system is involved at all stages of atherogenesisviaactivation of monocytes/macrophages and T lymphocytes.Circulating proinflammatory cytokines and chemokines produced by these cells interact with specific receptors on various cells and activate specific signaling pathways, leading to inflammation-induced atherosclerotic lesions. Recent studies have focused on predictive value of inflammatory biomarkers such as C-reactive protein and interleukin-6. These biomarkers were shown to be associated with poor quality of life and predictive of adverse events in coronary atherosclerosis and left ventricular dysfunction. Vascular predictive value of other numerous inflammatory markers is being investigated. We herein analyze the role of several mediators of inflammation, affecting vascular functions and leading toward atherosclerotic lesions.

The macrophage: the intersection between HIV infection and atherosclerosis

HIV-infected individuals are at increased risk of coronary artery disease (CAD) with underlying mechanisms including chronic immune activation and inflammation secondary to HIV-induced microbial translocation and low-grade endotoxemia; direct effects of HIV and viral proteins on macrophage cholesterol metabolism; and dyslipidemia related to HIV infection and specific antiretroviral therapies. Monocytes are the precursors of the lipid-laden foam cells within the atherosclerotic plaque and produce high levels of proinflammatory cytokines such as IL-6. The minor CD14+/CD16+ "proinflammatory" monocyte subpopulation is preferentially susceptible to HIV infection and may play a critical role in the pathogenesis of HIV-related CAD. In this review, the central role of monocytes/macrophages in HIV-related CAD and the importance of inflammation and cholesterol metabolism are discussed.