Dataset Information

High-Density Lipoprotein Binds to Mycobacterium avium and Affects the Infection of THP-1 Macrophages.

ABSTRACT: High-density lipoprotein (HDL) is involved in innate immunity toward various infectious diseases. Concerning bacteria, HDL is known to bind to lipopolysaccharide (LPS) and to neutralize its physiological activity. On the other hand, cholesterol is known to play an important role in mycobacterial entry into host cells and in survival in the intracellular environment. However, the pathogenicity of Mycobacterium avium (M. avium) infection, which tends to increase worldwide, remains poorly studied. Here we report that HDL indicated a stronger interaction with M. avium than that with other Gram-negative bacteria containing abundant LPS. A binding of apolipoprotein (apo) A-I, the main protein component of HDL, with a specific lipid of M. avium might participate in this interaction. HDL did not have a direct bactericidal activity toward M. avium but attenuated the engulfment of M. avium by THP-1 macrophages. HDL also did not affect bacterial killing after ingestion of live M. avium by THP-1 macrophage. Furthermore, HDL strongly promoted the formation of lipid droplets in M. avium-infected THP-1 macrophages. These observations provide new insights into the relationship between M. avium infection and host lipoproteins, especially HDL. Thus, HDL may help M. avium to escape from host innate immunity.

SUBMITTER: Ichimura N

PROVIDER: S-EPMC4969507 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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High-Density Lipoprotein Binds to Mycobacterium avium and Affects the Infection of THP-1 Macrophages.

Ichimura Naoya N Sato Megumi M Yoshimoto Akira A Yano Kouji K Ohkawa Ryunosuke R Kasama Takeshi T Tozuka Minoru M

Journal of lipids 20160719

High-density lipoprotein (HDL) is involved in innate immunity toward various infectious diseases. Concerning bacteria, HDL is known to bind to lipopolysaccharide (LPS) and to neutralize its physiological activity. On the other hand, cholesterol is known to play an important role in mycobacterial entry into host cells and in survival in the intracellular environment. However, the pathogenicity of Mycobacterium avium (M. avium) infection, which tends to increase worldwide, remains poorly studied. ...[more]

PMID: 27516907

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Project description:BackgroundMany efforts have been made to understand basal mechanisms of mycobacterial infections. Macrophages are the first line of host immune defence to encounter and eradicate mycobacteria. Pathogenic species have evolved different mechanisms to evade host response, e.g. by influencing macrophage apoptotic pathways. However, the underlying molecular regulation is not fully understood. A new layer of eukaryotic regulation of gene expression is constituted by microRNAs. Therefore, we present a comprehensive study for identification of these key regulators and their targets in the context of host macrophage response to mycobacterial infections.Methodology/principal findingsWe performed microRNA as well as mRNA expression analysis of human monocyte derived macrophages infected with several Mycobacterium avium hominissuis strains by means of microarrays as well as quantitative reverse transcription PCR (qRT-PCR). The data revealed the ability of all strains to inhibit apoptosis by transcriptional regulation of BCL2 family members. Accordingly, at 48 h after infection macrophages infected with all M. avium strains showed significantly decreased caspase 3 and 7 activities compared to the controls. Expression of let-7e, miR-29a and miR-886-5p were increased in response to mycobacterial infection at 48 h. The integrated analysis of microRNA and mRNA expression as well as target prediction pointed out regulative networks identifying caspase 3 and 7 as potential targets of let-7e and miR-29a, respectively. Consecutive reporter assays verified the regulation of caspase 3 and 7 by these microRNAs.Conclusions/significanceWe show for the first time that mycobacterial infection of human macrophages causes a specific microRNA response. We furthermore outlined a regulatory network of potential interactions between microRNAs and mRNAs. This study provides a theoretical concept for unveiling how distinct mycobacteria could manipulate host cell response. In addition, functional relevance was confirmed by uncovering the control of major caspases 3 and 7 by let-7e and miR-29a, respectively.

Project description:Introduction: Oxidative stress in monocyte-derived macrophages is a significant pathophysiological process in atherosclerosis. L-cystathionine (L-Cth) acts as a scavenger for oxygen free radicals. However, the impact of L-Cth on macrophage oxidative stress during atherogenesis has remained unclear. This study aimed to investigate whether L-Cth affects oxidative stress in THP-1-derived macrophages and its subsequent effects on DNA damage and cell apoptosis. Methods: We established a cellular model of oxLDL-stimulated macrophages. The content of superoxide anion, H2O2, NO, and H2S in the macrophage were in situ detected by the specific fluorescence probe, respectively. The activities of SOD, GSH-Px, and CAT were measured by colorimetrical assay. The protein expressions of SOD1, SOD2, and iNOS were detected using western blotting. The DNA damage and apoptosis in the macrophage was evaluated using an fluorescence kit. Results: The results demonstrated that oxLDL significantly increased the content of superoxide anion and H2O2, the expression of iNOS protein, and NO production in macrophages. Conversely, oxLDL decreased the activity of antioxidants GSH-Px, SOD, and CAT, and downregulated the protein expressions of SOD1 and SOD2 in macrophages. However, treatment with L-Cth reduced the levels of superoxide anion, H2O2, and NO, as well as the protein expression of iNOS induced by oxLDL. Moreover, L-Cth treatment significantly enhanced GSH-Px, SOD, and CAT activity, and upregulated the expressions of SOD1 and SOD2 proteins in macrophages treated with oxLDL. Furthermore, both L-Cth supplementation and activation of endogenous L-Cth production suppressed DNA damage and cell apoptosis in oxLDL-injured macrophages, whereas inhibition of endogenous L-Cth exacerbated the deleterious effects of oxLDL. Conclusion: These findings suggest that L-Cth exerts a pronounced inhibitory effect on the oxidative stress, subsequent DNA damage and cell apoptosis in oxLDL-stimulated THP-1 monocytes. This study deepens our understanding of the pathogenesis of macrophage-related cardiovascular pathology.

Dataset Information

High-Density Lipoprotein Binds to Mycobacterium avium and Affects the Infection of THP-1 Macrophages.

Publications

High-Density Lipoprotein Binds to Mycobacterium avium and Affects the Infection of THP-1 Macrophages.

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