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In conditions of limited commercial information on costs and rational costs, machines' efficiency and rational parameters at the stage of their manufacturing can be established based on an analysis of technical and operational indices. On this basis, the technical efficiency of the machine can be established. The corresponding technical and operational indices are calculated based on known technical parameters and operating conditions of the machine. These are such indices as specific energy consumption (kVt∙h/m3), material consumption (t∙h/m3), productivity (m3/h), output per worker (m3/w∙h), and several generalized indices derived from the indicated ones. The choice of a rational solution is based on single-criteria optimization (on the one-criterion analysis).

Background and Aims: We previously reported that Oxy210, an oxysterol-based drug candidate, exhibits antifibrotic and anti-inflammatory properties. We also showed that, in mice, it ameliorates hepatic hallmarks of non-alcoholic steatohepatitis (NASH), including inflammation and fibrosis, and reduces adipose tissue inflammation. Here, we aim to investigate the effects of Oxy210 on atherosclerosis, an inflammatory disease of the large arteries that is linked to NASH in epidemiologic studies, shares many of the same risk factors, and is the major cause of mortality in people with NASH., Methods: Oxy210 was studied in vivo in APOE*3-Leiden.CETP mice, a humanized mouse model for both NASH and atherosclerosis, in which symptoms are induced by consumption of a high fat, high cholesterol "Western" diet (WD). Oxy210 was also studied in vitro using two cell types that are important in atherogenesis: human aortic endothelial cells (HAECs) and macrophages treated with atherogenic and inflammatory agents., Results: Oxy210 reduced atherosclerotic lesion formation by more than 50% in hyperlipidemic mice fed the WD for 16 weeks. This was accompanied by reduced plasma cholesterol levels and reduced macrophages in lesions. In HAECs and macrophages, Oxy210 reduced the expression of key inflammatory markers associated with atherosclerosis, including interleukin-1 beta ( IL-1β ), interleukin-6 ( IL-6 ), tumor necrosis factor-α ( TNF-α ), chemokine (C-C motif) ligand 2 ( CCL2 ), vascular cell adhesion molecule-1 ( VCAM-1 ), and E-Selectin . In addition, cholesterol efflux was significantly enhanced in macrophages treated with Oxy210., Conclusions: These findings suggest that Oxy210 could be a drug candidate for targeting both NASH and atherosclerosis, as well as chronic inflammation associated with the manifestations of metabolic syndrome.

Extracellular vesicles (EVs) serve as pivotal mediators of intercellular communication in both health and disease, delivering biologically active molecules from vesicle-producing cells to recipient cells. In the context of HIV infection, EVs have been shown to carry the viral protein Nef, a key pathogenic factor associated with HIV-related co-morbidities. Despite this recognition, the specific localisation of Nef within the vesicles has remained elusive. This study addresses this critical knowledge gap by investigating Nef-containing EVs. Less than 1% of the total released Nef was associated with EVs; most Nef existed as free protein released by damaged cells. Nevertheless, activity of EV-associated Nef in downregulating the major cholesterol transporter ABCA1, a critical aspect linked to the pathogenic effects of Nef, was comparable to that of free Nef present in the supernatant. Through a series of biochemical and microscopic assays, we demonstrate that the majority of EV-associated Nef molecules are localised on the external surface of the vesicles. This distinctive distribution prompts the consideration of Nef-containing EVs as potential targets for immunotherapeutic interventions aimed at preventing or treating HIV-associated co-morbidities. In conclusion, our results shed light on the localisation and functional activity of Nef within EVs, providing valuable insights for the development of targeted immunotherapies to mitigate the impact of HIV-associated co-morbidities., (© 2024 The Author(s). Journal of Extracellular Vesicles published by Wiley Periodicals LLC on behalf of International Society for Extracellular Vesicles.)

There are several interactions within the tumor microenvironment (TME) that affect the response of cancer cells to therapy. There are also a large number of cells and secretions in TME that increase resistance to therapy. Following the release of immunosuppressive, pro-angiogenic, and metastatic molecules by certain cells such as tumor-associated macrophages (TAMs), cancer-associated fibroblasts (CAFs), and cancer cells, immune evasion, angiogenesis, and metastasis may be induced. However, natural killer (NK) cells and cytotoxic CD8 + T lymphocytes (CTLs) can responsively release anticancer molecules. In addition, anticancer drugs can modulate these cells and their interactions in favor of either cancer resistance or therapy. Docetaxel belongs to taxanes, a class of anti-tumor drugs, which acts through the polymerization of tubulin and the induction of cell cycle arrest. Also, it has been revealed that taxanes including docetaxel affect cancer cells and the other cells within TME through some other mechanisms such as modulation of immune system responses, angiogenesis, and metastasis. In this paper, we explain the basic mechanisms of docetaxel interactions with malignant cells. Besides, we review the diverse effects of docetaxel on TME and cancer cells in consequence. Lastly, the modulatory effects of docetaxel alone or in conjunction with other anticancer agents on anti-tumor immunity, cancer cell resistance, angiogenesis, and metastasis will be discussed., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

A possible explanation for chronic inflammation in HIV-infected individuals treated with anti-retroviral therapy is hyperreactivity of myeloid cells due to a phenomenon called "trained immunity." Here, we demonstrate that human monocyte-derived macrophages originating from monocytes initially treated with extracellular vesicles containing HIV-1 protein Nef (exNef), but differentiating in the absence of exNef, release increased levels of pro-inflammatory cytokines after lipopolysaccharide stimulation. This effect is associated with chromatin changes at the genes involved in inflammation and cholesterol metabolism pathways and upregulation of the lipid rafts and is blocked by methyl-β-cyclodextrin, statin, and an inhibitor of the lipid raft-associated receptor IGF1R. Bone-marrow-derived macrophages from exNef-injected mice, as well as from mice transplanted with bone marrow from exNef-injected animals, produce elevated levels of tumor necrosis factor α (TNF-α) upon stimulation. These phenomena are consistent with exNef-induced trained immunity that may contribute to persistent inflammation and associated co-morbidities in HIV-infected individuals with undetectable HIV load., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)

In this research, samples of an alloy with a bimodal structure were studied on the basis of a previously developed technology for obtaining hydrogen storage materials based on the Ti-Al-Nb system. The results of SPS of mechanically activated powder mixtures of the Ti-Al-Nb system at a temperature of 1300 °C make it possible to obtain an alloy with a predominantly bimodal structure. However, an insignificant presence of TiAl 3 , AlNb 2 phases, and unreacted niobium is still observed in the structure. The mechanical properties of alloys of the Ti-Al-Nb system after sintering show abnormally low values of strength and ductility (less than 150 MPa). Two-stage heat treatment of alloys of the Ti-Al-Nb system leads to the decomposition of large precipitates of TiAl 3 with the formation of O-phase nuclei, as well as to the complete dissolution of unreacted niobium and AlNb 2 phases. Heat treatment of alloys of the Ti-Al-Nb system contributes to an increase in its strength by approximately 10 times (1310 MPa, MA-180), and ductility by 2 times (1322 MPa, MA-20). The surface fracture of samples obtained after testing is characterized by intergranular (intercrystalline) brittle fracture with "river" or "step" features.

Low-grade persistent inflammation is a feature of diabetes-driven vascular complications, in particular activation of the Nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome to trigger the maturation and release of the inflammatory cytokine interleukin-1β (IL-1β). We investigated whether inhibiting the NLRP3 inflammasome, through the use of the specific small-molecule NLRP3 inhibitor MCC950, could reduce inflammation, improve vascular function, and protect against diabetes-associated atherosclerosis in the streptozotocin-induced diabetic apolipoprotein E-knockout mouse. Diabetes led to an approximately fourfold increase in atherosclerotic lesions throughout the aorta, which were significantly attenuated with MCC950 ( P < 0.001). This reduction in lesions was associated with decreased monocyte-macrophage content, reduced necrotic core, attenuated inflammatory gene expression (IL-1β, tumor necrosis factor-α, intracellular adhesion molecule 1, and MCP-1; P < 0.05), and reduced oxidative stress, while maintaining fibrous cap thickness. Additionally, vascular function was improved in diabetic vessels of mice treated with MCC950 ( P < 0.05). In a range of cell lines (murine bone marrow-derived macrophages, human monocytic THP-1 cells, phorbol 12-myristate 13-acetate-differentiated human macrophages, and aortic smooth muscle cells from humans with diabetes), MCC950 significantly reduced IL-1β and/or caspase-1 secretion and attenuated leukocyte-smooth muscle cell interactions under high glucose or lipopolysaccharide conditions. In summary, MCC950 reduces plaque development, promotes plaque stability, and improves vascular function, suggesting that targeting NLRP3-mediated inflammation is a novel therapeutic strategy to improve diabetes-associated vascular disease., (© 2020 by the American Diabetes Association.)

Lipoproteins play a key role in transport of cholesterol to and from tissues. Recent studies have also demonstrated that red blood cells (RBCs), which carry large quantities of free cholesterol in their membrane, play an important role in reverse cholesterol transport. However, the exact role of RBCs in systemic cholesterol metabolism is poorly understood. RBCs were incubated with autologous plasma or isolated lipoproteins resulting in a significant net amount of cholesterol moved from RBCs to HDL, while cholesterol from LDL moved in the opposite direction. Furthermore, the bi-directional cholesterol transport between RBCs and plasma lipoproteins was saturable and temperature-, energy-, and time-dependent, consistent with an active process. We did not find LDLR, ABCG1, or scavenger receptor class B type 1 in RBCs but found a substantial amount of ABCA1 mRNA and protein. However, specific cholesterol efflux from RBCs to isolated apoA-I was negligible, and ABCA1 silencing with siRNA or inhibition with vanadate and Probucol did not inhibit the efflux to apoA-I, HDL, or plasma. Cholesterol efflux from and cholesterol uptake by RBCs from Abca1 +/+ and Abca1 -/- mice were similar, arguing against the role of ABCA1 in cholesterol flux between RBCs and lipoproteins. Bioinformatics analysis identified ABCA7, ABCG5, lipoprotein lipase, and mitochondrial translocator protein as possible candidates that may mediate the cholesterol flux. Together, these results suggest that RBCs actively participate in cholesterol transport in the blood, but the role of cholesterol transporters in RBCs remains uncertain., Competing Interests: Conflict of interest—The authors declare that they have no conflicts of interest with the contents of this article.

Objective: AIBP (apolipoprotein A-I binding protein) is an effective and selective regulator of lipid rafts modulating many metabolic pathways originating from the rafts, including inflammation. The mechanism of action was suggested to involve stimulation by AIBP of cholesterol efflux, depleting rafts of cholesterol, which is essential for lipid raft integrity. Here we describe a different mechanism contributing to the regulation of lipid rafts by AIBP. Approach and Results: We demonstrate that modulation of rafts by AIBP may not exclusively depend on the rate of cholesterol efflux or presence of the key regulator of the efflux, ABCA1 (ATP-binding cassette transporter A-I). AIBP interacted with phosphatidylinositol 3-phosphate, which was associated with increased abundance and activation of Cdc42 and rearrangement of the actin cytoskeleton. Cytoskeleton rearrangement was accompanied with reduction of the abundance of lipid rafts, without significant changes in the lipid composition of the rafts. The interaction of AIBP with phosphatidylinositol 3-phosphate was blocked by AIBP substrate, NADPH (nicotinamide adenine dinucleotide phosphate), and both NADPH and silencing of Cdc42 interfered with the ability of AIBP to regulate lipid rafts and cholesterol efflux., Conclusions: Our findings indicate that an underlying mechanism of regulation of lipid rafts by AIBP involves PIP-dependent rearrangement of the cytoskeleton.

HIV-associated neurocognitive disorders (HANDs) are a frequent outcome of HIV infection. Effective treatment of HIV infection has reduced the rate of progression and severity but not the overall prevalence of HANDs, suggesting ongoing pathological process even when viral replication is suppressed. In this study, we investigated how HIV-1 protein Nef secreted in extracellular vesicles (exNef) impairs neuronal functionality. ExNef were rapidly taken up by neural cells in vitro , reducing the abundance of ABC transporter A1 (ABCA1) and thus cholesterol efflux and increasing the abundance and modifying lipid rafts in neuronal plasma membranes. ExNef caused a redistribution of amyloid precursor protein (APP) and Tau to lipid rafts and increased the abundance of these proteins, as well as of Aβ 42 ExNef further potentiated phosphorylation of Tau and activation of inflammatory pathways. These changes were accompanied by neuronal functional impairment. Disruption of lipid rafts with cyclodextrin reversed the phenotype. Short-term treatment of C57BL/6 mice with either purified recombinant Nef or exNef similarly resulted in reduced abundance of ABCA1 and elevated abundance of APP in brain tissue. The abundance of ABCA1 in brain tissue of HIV-infected human subjects diagnosed with HAND was lower, and the abundance of lipid rafts was higher compared with HIV-negative individuals. Levels of APP and Tau in brain tissue correlated with the abundance of Nef. Thus, modification of neuronal cholesterol trafficking and of lipid rafts by Nef may contribute to early stages of neurodegeneration and pathogenesis in HAND., Competing Interests: Conflict of interest—The authors declare that they have no conflicts of interest with the contents of this article., (© 2020 Ditiatkovski et al.)

Lipid rafts are distinct liquid-ordered domains of plasma membranes of most eukaryotic cells providing platform for signaling pathways. Lipid composition of rafts is critical for their structural integrity and for regulation of signaling pathways originating from rafts. Here we provide a protocol to isolate lipid rafts from cultured human and animal cells and comprehensively analyse their lipid composition., Competing Interests: Competing interestsThe authors declare no competing interests related to this work., (Copyright © 2020 The Authors; exclusive licensee Bio-protocol LLC.)

Lipid rafts, solid regions of the plasma membrane enriched in cholesterol and glycosphingolipids, are essential parts of a cell. Functionally, lipid rafts present a platform that facilitates interaction of cells with the outside world. However, the unique properties of lipid rafts required to fulfill this function at the same time make them susceptible to exploitation by pathogens. Many steps of pathogen interaction with host cells, and sometimes all steps within the entire lifecycle of various pathogens, rely on host lipid rafts. Such steps as binding of pathogens to the host cells, invasion of intracellular parasites into the cell, the intracellular dwelling of parasites, microbial assembly and exit from the host cell, and microbe transfer from one cell to another all involve lipid rafts. Interaction also includes modification of lipid rafts in host cells, inflicted by pathogens from both inside and outside the cell, through contact or remotely, to advance pathogen replication, to utilize cellular resources, and/or to mitigate immune response. Here, we provide a systematic overview of how and why pathogens interact with and exploit host lipid rafts, as well as the consequences of this interaction for the host, locally and systemically, and for the microbe. We also raise the possibility of modulation of lipid rafts as a therapeutic approach against a variety of infectious agents., (Copyright © 2020 Bukrinsky et al.)

Lipid rafts regulate the initiation of cellular metabolic and signaling pathways by organizing the pathway components in ordered microdomains on the cell surface. Cellular responses regulated by lipid rafts range from physiological to pathological, and the success of a therapeutic approach targeting "pathological" lipid rafts depends on the ability of a remedial agent to recognize them and disrupt pathological lipid rafts without affecting normal raft-dependent cellular functions. In this article, concluding the Thematic Review Series on Biology of Lipid Rafts, we review current experimental therapies targeting pathological lipid rafts, including examples of inflammarafts and clusters of apoptotic signaling molecule-enriched rafts. The corrective approaches include regulation of cholesterol and sphingolipid metabolism and membrane trafficking by using HDL and its mimetics, LXR agonists, ABCA1 overexpression, and cyclodextrins, as well as a more targeted intervention with apoA-I binding protein. Among others, we highlight the design of antagonists that target inflammatory receptors only in their activated form of homo- or heterodimers, when receptor dimerization occurs in pathological lipid rafts. Other therapies aim to promote raft-dependent physiological functions, such as augmenting caveolae-dependent tissue repair. The overview of this highly dynamic field will provide readers with a view on the emerging concept of targeting lipid rafts as a therapeutic strategy.jlr;61/5/687/F1F1f1., (Copyright © 2020 Sviridov et al.)

Dysregulation of lipid homeostasis is intimately associated with defects in insulin secretion, a key feature of type 2 diabetes. Here, we explore the role of the putative lipid transporter ABCA12 in regulating insulin secretion from β-cells. Mice with β-cell-specific deletion of Abca12 display impaired glucose-stimulated insulin secretion and eventual islet inflammation and β-cell death. ABCA12's action in the pancreas is independent of changes in the abundance of two other cholesterol transporters, ABCA1 and ABCG1, or of changes in cellular cholesterol or ceramide content. Instead, loss of ABCA12 results in defects in the genesis and fusion of insulin secretory granules and increases in the abundance of lipid rafts at the cell membrane. These changes are associated with dysregulation of the small GTPase CDC42 and with decreased actin polymerisation. Our findings establish a new, pleiotropic role for ABCA12 in regulating pancreatic lipid homeostasis and insulin secretion., (© 2020 The Authors.)

Apolipoprotein A-I binding protein (AIBP) is a protein involved in regulation of lipid rafts and cholesterol efflux. AIBP has been suggested to function as a protective factor under several sets of pathological conditions associated with increased abundance of lipid rafts, such as atherosclerosis and acute lung injury. Here, we show that exogenously added AIBP reduced the abundance of lipid rafts and inhibited HIV replication in vitro as well as in HIV-infected humanized mice, whereas knockdown of endogenous AIBP increased HIV replication. Endogenous AIBP was much more abundant in activated T cells than in monocyte-derived macrophages (MDMs), and exogenous AIBP was much less effective in T cells than in MDMs. AIBP inhibited virus-cell fusion, specifically targeting cells with lipid rafts mobilized by cell activation or Nef-containing exosomes. MDM-HIV fusion was sensitive to AIBP only in the presence of Nef provided by the virus or exosomes. Peripheral blood mononuclear cells from donors with the HLA-B*35 genotype, associated with rapid progression of HIV disease, bound less AIBP than cells from donors with other HLA genotypes and were not protected by AIBP from rapid HIV-1 replication. These results provide the first evidence for the role of Nef exosomes in regulating HIV-cell fusion by modifying lipid rafts and suggest that AIBP is an innate factor that restricts HIV replication by targeting lipid rafts. IMPORTANCE Apolipoprotein A-I binding protein (AIBP) is a recently identified innate anti-inflammatory factor. Here, we show that AIBP inhibited HIV replication by targeting lipid rafts and reducing virus-cell fusion. Importantly, AIBP selectively reduced levels of rafts on cells stimulated by an inflammatory stimulus or treated with extracellular vesicles containing HIV-1 protein Nef without affecting rafts on nonactivated cells. Accordingly, fusion of monocyte-derived macrophages with HIV was sensitive to AIBP only in the presence of Nef. Silencing of endogenous AIBP significantly upregulated HIV-1 replication. Interestingly, HIV-1 replication in cells from donors with the HLA-B*35 genotype, associated with rapid progression of HIV disease, was not inhibited by AIBP. These results suggest that AIBP is an innate anti-HIV factor that targets virus-cell fusion., (Copyright © 2020 Dubrovsky et al.)

HIV infection has a profound effect on "bystander" cells causing metabolic co-morbidities. This may be mediated by exosomes secreted by HIV-infected cells and containing viral factors. Here we show that exosomes containing HIV-1 protein Nef (exNef) are rapidly taken up by macrophages releasing Nef into the cell interior. This caused down-regulation of ABCA1, reduction of cholesterol efflux and sharp elevation of the abundance of lipid rafts through reduced activation of small GTPase Cdc42 and decreased actin polymerization. Changes in rafts led to re-localization of TLR4 and TREM-1 to rafts, phosphorylation of ERK1/2, activation of NLRP3 inflammasome, and increased secretion of pro-inflammatory cytokines. The effects of exNef on lipid rafts and on inflammation were reversed by overexpression of a constitutively active mutant of Cdc42. Similar effects were observed in macrophages treated with exosomes produced by HIV-infected cells or isolated from plasma of HIV-infected subjects, but not with exosomes from cells and subjects infected with ΔNef-HIV or uninfected subjects. Mice injected with exNef exhibited monocytosis, reduced ABCA1 in macrophages, increased raft abundance in monocytes and augmented inflammation. Thus, Nef-containing exosomes potentiated pro-inflammatory response by inducing changes in cholesterol metabolism and reorganizing lipid rafts. These mechanisms may contribute to HIV-associated metabolic co-morbidities., Competing Interests: The authors have declared that no competing interests exist.

HIV infection is known to be associated with cardiometabolic abnormalities; here we investigated the progression and causes of these abnormalities. Three groups of participants were recruited: HIV-negative subjects and two groups of treatment-naïve HIV-positive subjects, one group initiating antiretroviral treatment, the other remaining untreated. Intima-media thickness (cIMT) increased in HIV-positive untreated group compared to HIV-negative group, but treatment mitigated the difference. We found no increase in diabetes-related metabolic markers or in the level of inflammation in any of the groups. Total cholesterol, low density lipoprotein cholesterol and apoB levels were lower in HIV-positive groups, while triglyceride and Lp(a) levels did not differ between the groups. We found a statistically significant negative association between viral load and plasma levels of total cholesterol, LDL cholesterol, HDL cholesterol, apoA-I and apoB. HIV-positive patients had hypoalphalipoproteinemia at baseline, and we found a redistribution of sub-populations of high density lipoprotein (HDL) particles with increased proportion of smaller HDL in HIV-positive untreated patients, which may result from increased levels of plasma cholesteryl ester transfer protein in this group. HDL functionality declined in the HIV-negative and HIV-positive untreated groups, but not in HIV-positive treated group. We also found differences between HIV-positive and negative groups in plasma abundance of several microRNAs involved in lipid metabolism. Our data support a hypothesis that cardiometabolic abnormalities in HIV infection are caused by HIV and that antiretroviral treatment itself does not influence key cardiometabolic parameters, but mitigates those affected by HIV., Competing Interests: The authors have declared that no competing interests exist.

Emerging evidence points to an important connection between pathogenesis of intracellular infections and host cholesterol metabolism. In our study we demonstrated that human cytomegalovirus exploits host small GTPase Cdc42 to hijack cellular cholesterol efflux pathway. It appears that the virus uses host machinery to stimulate cholesterol efflux by modifying lipid rafts and altering properties of plasma membrane, but the altered pathway is controlled by the viral protein US28 instead of the host ATP binding cassette transporter A1. We speculate that virus-controlled remodeling of plasma membrane facilitates immune evasion, exocytosis of viral proteins and cell-to-cell transmission of human cytomegalovirus. These mechanisms may be not unique for the cytomegalovirus and subverting reverse cholesterol transport pathway may be a generic mechanism used by pathogens to alter properties of host plasma membrane adapting it for their purposes-to hide and disseminate.

Aims: The recent failures of HDL-raising therapies have underscored our incomplete understanding of HDL biology. Therefore there is an urgent need to comprehensively investigate HDL metabolism to enable the development of effective HDL-centric therapies. To identify novel regulators of HDL metabolism, we performed a joint analysis of human genetic, transcriptomic, and plasma HDL-cholesterol (HDL-C) concentration data and identified a novel association between trafficking protein, kinesin binding 2 (TRAK2) and HDL-C concentration. Here we characterize the molecular basis of the novel association between TRAK2 and HDL-cholesterol concentration., Methods and Results: Analysis of lymphocyte transcriptomic data together with plasma HDL from the San Antonio Family Heart Study (n = 1240) revealed a significant negative correlation between TRAK2 mRNA levels and HDL-C concentration, HDL particle diameter and HDL subspecies heterogeneity. TRAK2 siRNA-mediated knockdown significantly increased cholesterol efflux to apolipoprotein A-I and isolated HDL from human macrophage (THP-1) and liver (HepG2) cells by increasing the mRNA and protein expression of the cholesterol transporter ATP-binding cassette, sub-family A member 1 (ABCA1). The effect of TRAK2 knockdown on cholesterol efflux was abolished in the absence of ABCA1, indicating that TRAK2 functions in an ABCA1-dependent efflux pathway. TRAK2 knockdown significantly increased liver X receptor (LXR) binding at the ABCA1 promoter, establishing TRAK2 as a regulator of LXR-mediated transcription of ABCA1., Conclusion: We show, for the first time, that TRAK2 is a novel regulator of LXR-mediated ABCA1 expression, cholesterol efflux, and HDL biogenesis. TRAK2 may therefore be an important target in the development of anti-atherosclerotic therapies., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.)

Objective: ABCA1 (ATP-binding cassette transporter A1) is the principal protein responsible for cellular cholesterol efflux. Abundance and functionality of ABCA1 is regulated both transcriptionally and post-translationally, with endocytosis of ABCA1 being an important element of post-translational regulation. Functional ABCA1 resides on the plasma membrane but can be internalized and either degraded or recycled back to the plasma membrane. The interaction between the degradative and recycling pathways determines the abundance of ABCA1 and may contribute to the efflux of intracellular cholesterol., Approach and Results: Here, we show that the principal pathway responsible for the internalization of ABCA1 leading to its degradation in macrophages is ARF6-dependent endocytic pathway. This pathway was predominant in the regulation of ABCA1 abundance and efflux of plasma membrane cholesterol. Conversely, the efflux of intracellular cholesterol was predominantly controlled by ARF6-independent pathways, and inhibition of ARF6 shifted ABCA1 into recycling endosomes enhancing efflux of intracellular cholesterol., Conclusions: We conclude that ARF6-dependent pathway is the predominant route responsible for the ABCA1 internalization and degradation, whereas ARF6-independent endocytic pathways may contribute to ABCA1 recycling and efflux of intracellular cholesterol., (© 2016 American Heart Association, Inc.)

Cytomegalovirus (HCMV) contains cholesterol, but how HCMV interacts with host cholesterol metabolism is unknown. We found that, in human fibroblasts, HCMV infection increased the efflux of cellular cholesterol, despite reducing the abundance of ABCA1. Mechanistically, viral protein US28 was acting through CDC42, rearranging actin microfilaments, causing association of actin with lipid rafts, and leading to a dramatic change in the abundance and/or structure of lipid rafts. These changes displaced ABCA1 from the cell surface but created new binding sites for apolipoprotein A-I, resulting in enhanced cholesterol efflux. The changes also reduced the inflammatory response in macrophages. HCMV infection modified the host lipidome profile and expression of several genes and microRNAs involved in cholesterol metabolism. In mice, murine CMV infection elevated plasma triglycerides but did not affect the level and functionality of high-density lipoprotein. Thus, HCMV, through its protein US28, reorganizes lipid rafts and disturbs cell cholesterol metabolism., (Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.)

Cholesterol is an essential component of the cellular membranes and, by extension, of the HIV envelope membrane, which is derived from the host cell plasma membrane. Depletion of the cellular cholesterol has an inhibitory effect on HIV assembly, reduces infectivity of the produced virions, and makes the cell less susceptible to HIV infection. It is not surprising that the virus has evolved to gain access to cellular proteins regulating cholesterol metabolism. One of the key mechanisms used by HIV to maintain high levels of cholesterol in infected cells is Nef-mediated inhibition of cholesterol efflux and the cholesterol transporter responsible for this process, ABCA1. In this chapter, we describe methods to investigate these effects of HIV-1 infection.