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Orekhov AN, Nikiforov NG, Sukhorukov VN, Kubekina MV, Sobenin IA, Wu WK, Foxx KK, Pintus S, Stegmaier P, Stelmashenko D, Kel A, Gratchev AN, Melnichenko AA, Wetzker R, Summerhill VI, Manabe I, Oishi Y. Role of Phagocytosis in the Pro-Inflammatory Response in LDL-Induced Foam Cell Formation; a Transcriptome Analysis. Int J Mol Sci 2020; 21:ijms21030817. [PMID: 32012706 PMCID: PMC7037225 DOI: 10.3390/ijms21030817] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 01/14/2020] [Accepted: 01/23/2020] [Indexed: 12/25/2022] Open
Abstract
Excessive accumulation of lipid inclusions in the arterial wall cells (foam cell formation) caused by modified low-density lipoprotein (LDL) is the earliest and most noticeable manifestation of atherosclerosis. The mechanisms of foam cell formation are not fully understood and can involve altered lipid uptake, impaired lipid metabolism, or both. Recently, we have identified the top 10 master regulators that were involved in the accumulation of cholesterol in cultured macrophages induced by the incubation with modified LDL. It was found that most of the identified master regulators were related to the regulation of the inflammatory immune response, but not to lipid metabolism. A possible explanation for this unexpected result is a stimulation of the phagocytic activity of macrophages by modified LDL particle associates that have a relatively large size. In the current study, we investigated gene regulation in macrophages using transcriptome analysis to test the hypothesis that the primary event occurring upon the interaction of modified LDL and macrophages is the stimulation of phagocytosis, which subsequently triggers the pro-inflammatory immune response. We identified genes that were up- or downregulated following the exposure of cultured cells to modified LDL or latex beads (inert phagocytosis stimulators). Most of the identified master regulators were involved in the innate immune response, and some of them were encoding major pro-inflammatory proteins. The obtained results indicated that pro-inflammatory response to phagocytosis stimulation precedes the accumulation of intracellular lipids and possibly contributes to the formation of foam cells. In this way, the currently recognized hypothesis that the accumulation of lipids triggers the pro-inflammatory response was not confirmed. Comparative analysis of master regulators revealed similarities in the genetic regulation of the interaction of macrophages with naturally occurring LDL and desialylated LDL. Oxidized and desialylated LDL affected a different spectrum of genes than naturally occurring LDL. These observations suggest that desialylation is the most important modification of LDL occurring in vivo. Thus, modified LDL caused the gene regulation characteristic of the stimulation of phagocytosis. Additionally, the knock-down effect of five master regulators, such as IL15, EIF2AK3, F2RL1, TSPYL2, and ANXA1, on intracellular lipid accumulation was tested. We knocked down these genes in primary macrophages derived from human monocytes. The addition of atherogenic naturally occurring LDL caused a significant accumulation of cholesterol in the control cells. The knock-down of the EIF2AK3 and IL15 genes completely prevented cholesterol accumulation in cultured macrophages. The knock-down of the ANXA1 gene caused a further decrease in cholesterol content in cultured macrophages. At the same time, knock-down of F2RL1 and TSPYL2 did not cause an effect. The results obtained allowed us to explain in which way the inflammatory response and the accumulation of cholesterol are related confirming our hypothesis of atherogenesis development based on the following viewpoints: LDL particles undergo atherogenic modifications that, in turn, accompanied by the formation of self-associates; large LDL associates stimulate phagocytosis; as a result of phagocytosis stimulation, pro-inflammatory molecules are secreted; these molecules cause or at least contribute to the accumulation of intracellular cholesterol. Therefore, it became obvious that the primary event in this sequence is not the accumulation of cholesterol but an inflammatory response.
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Affiliation(s)
- Alexander N. Orekhov
- Laboratory of Angiopathology, Institute of General Pathology and Pathophysiology, 8 Baltiiskaya Street, 125315 Moscow, Russia
- Laboratory of Infection Pathology and Molecular Microecology, Institute of Human Morphology, 3 Tsyurupa Street, 117418 Moscow, Russia
- Correspondence: (A.N.O.); (V.I.S.)
| | - Nikita G. Nikiforov
- Laboratory of Angiopathology, Institute of General Pathology and Pathophysiology, 8 Baltiiskaya Street, 125315 Moscow, Russia
- Laboratory of Medical Genetics, Institute of Experimental Cardiology, National Medical Research Center of Cardiology, 15A 3-rd Cherepkovskaya Street, 121552 Moscow, Russia
- Centre of Collective Usage, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilova Street, 119334 Moscow, Russia
| | - Vasily N. Sukhorukov
- Laboratory of Angiopathology, Institute of General Pathology and Pathophysiology, 8 Baltiiskaya Street, 125315 Moscow, Russia
- Laboratory of Infection Pathology and Molecular Microecology, Institute of Human Morphology, 3 Tsyurupa Street, 117418 Moscow, Russia
| | - Marina V. Kubekina
- Centre of Collective Usage, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilova Street, 119334 Moscow, Russia
| | - Igor A. Sobenin
- Laboratory of Angiopathology, Institute of General Pathology and Pathophysiology, 8 Baltiiskaya Street, 125315 Moscow, Russia
- Laboratory of Medical Genetics, Institute of Experimental Cardiology, National Medical Research Center of Cardiology, 15A 3-rd Cherepkovskaya Street, 121552 Moscow, Russia
| | - Wei-Kai Wu
- Department of Internal Medicine, National Taiwan University Hospital, Bei-Hu Branch, Taipei 10002, Taiwan
| | - Kathy K. Foxx
- Kalen Biomedical, LLC, Montgomery Village, MD 20886, USA
| | - Sergey Pintus
- BIOSOFT.RU, LLC, 630090 Novosibirsk, Russia
- Institute of Computational Technologies, 630090 Novosibirsk, Russia
| | | | - Daria Stelmashenko
- BIOSOFT.RU, LLC, 630090 Novosibirsk, Russia
- geneXplain GmbH, 38302 Wolfenbüttel, Germany
| | - Alexander Kel
- BIOSOFT.RU, LLC, 630090 Novosibirsk, Russia
- geneXplain GmbH, 38302 Wolfenbüttel, Germany
- Institute of Chemical Biology and Fundamental Medicine, 630090 Novosibirsk, Russia
| | - Alexei N. Gratchev
- N. N. Blokhin National Medical Research Center of Oncology, 24 Kashirskoye sh., 115478 Moscow, Russia
| | - Alexandra A. Melnichenko
- Laboratory of Angiopathology, Institute of General Pathology and Pathophysiology, 8 Baltiiskaya Street, 125315 Moscow, Russia
- Laboratory of Medical Genetics, Institute of Experimental Cardiology, National Medical Research Center of Cardiology, 15A 3-rd Cherepkovskaya Street, 121552 Moscow, Russia
| | - Reinhard Wetzker
- Department of Anaesthesiology and Intensive Care Medicine, University Hospital Jena, Am Klinikum 1, D-07747 Jena, Germany
| | - Volha I. Summerhill
- Department of Basic Research, Institute for Atherosclerosis Research, 121609 Moscow, Russia
- Correspondence: (A.N.O.); (V.I.S.)
| | - Ichiro Manabe
- Department of Aging Research, Graduate School of Medicine, Chiba University, Chiba 263-8522, Japan
| | - Yumiko Oishi
- Department of Biochemistry & Molecular Biology, Nippon Medical School, Tokyo 113-8602, Japan
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Kolpakov V, Polishchuk R, Bannykh S, Rekhter M, Solovjev P, Romanov Y, Tararak E, Antonov A, Mironov A. Atherosclerosis-prone branch regions in human aorta: microarchitecture and cell composition of intima. Atherosclerosis 1996; 122:173-89. [PMID: 8769681 DOI: 10.1016/0021-9150(95)05735-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The microarchitecture and cell composition of intima were studied at the macroscopically unaffected branch regions of human thoracic aorta using en face preparations, scanning and transmission electron microscopy, and immunohistochemistry. The endothelial lining showed a heterogeneous pattern and altered morphology including the areas of deendothelialization covered with platelets and dilated intercellular clefts. Leukocyte adhesion, accumulation of subendothelial macrophages and lymphocytes were characteristic of proximal and lateral zones, while the flow divider showed no significant accumulation of blood cells. Smooth muscle cells (SMCs) on the flow divider were elongated, in a contractile state, contacted side-by-side and did not contain lipid inclusions. In the lateral and proximal zones, intima appeared to be a network of stellate SMCs which were in contact through their processes. Most of the SMCs were in a synthetic state and many of them contained small lipid droplets. The number of procollagen I positive cells and the volume of extracellular components were most significant at the lateral zones rather than at the flow divider. We did not observe any difference in the rate of proliferation. Our results suggest that the intimal layer at the lateral and proximal zones has some distinct structural peculiarities, which provoke the development of initial atherosclerotic lesions at these sites. Such an intimal structure is probably caused by different flow patterns at these zone. However, only the totality of different morphological features exhibited in the area of altered vascular wall shear stress may be considered as a prerequisite for atherosclerotic lesions.
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Affiliation(s)
- V Kolpakov
- Department of Anatomy, Ivanovo State Medical Academy, Russia
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