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Benedict B, Kristensen SM, Duxin JP. What are the DNA lesions underlying formaldehyde toxicity? DNA Repair (Amst) 2024; 138:103667. [PMID: 38554505 DOI: 10.1016/j.dnarep.2024.103667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 02/22/2024] [Accepted: 03/01/2024] [Indexed: 04/01/2024]
Abstract
Formaldehyde is a highly reactive organic compound. Humans can be exposed to exogenous sources of formaldehyde, but formaldehyde is also produced endogenously as a byproduct of cellular metabolism. Because formaldehyde can react with DNA, it is considered a major endogenous source of DNA damage. However, the nature of the lesions underlying formaldehyde toxicity in cells remains vastly unknown. Here, we review the current knowledge of the different types of nucleic acid lesions that are induced by formaldehyde and describe the repair pathways known to counteract formaldehyde toxicity. Taking this knowledge together, we discuss and speculate on the predominant lesions generated by formaldehyde, which underly its natural toxicity.
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Affiliation(s)
- Bente Benedict
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Stella Munkholm Kristensen
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Julien P Duxin
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark.
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2
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Sahlström P, Joshua V, Valkovskaia V, Biese C, Stålesen R, Israelsson L, Végvári Á, Scheel-Toellner D, Klareskog L, Hansson M, Hensvold A, Malmström V, Grönwall C. Autoreactive B cells against malondialdehyde-induced protein cross-links are present in the joint, lung, and bone marrow of rheumatoid arthritis patients. J Biol Chem 2023; 299:105320. [PMID: 37802315 PMCID: PMC10641667 DOI: 10.1016/j.jbc.2023.105320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 09/28/2023] [Indexed: 10/08/2023] Open
Abstract
Autoantibodies to malondialdehyde (MDA) proteins constitute a subset of anti-modified protein autoantibodies in rheumatoid arthritis (RA), which is distinct from citrulline reactivity. Serum anti-MDA IgG levels are commonly elevated in RA and correlate with disease activity, CRP, IL6, and TNF-α. MDA is an oxidation-associated reactive aldehyde that together with acetaldehyde mediates formation of various immunogenic amino acid adducts including linear MDA-lysine, fluorescent malondialdehyde acetaldehyde (MAA)-lysine, and intramolecular cross-linking. We used single-cell cloning, generation of recombinant antibodies (n = 356 from 25 donors), and antigen-screening to investigate the presence of class-switched MDA/MAA+ B cells in RA synovium, bone marrow, and bronchoalveolar lavage. Anti-MDA/MAA+ B cells were found in bone marrow plasma cells of late disease and in the lung of both early disease and risk-individuals and in different B cell subsets (memory, double negative B cells). These were compared with previously identified anti-MDA/MAA from synovial memory and plasma cells. Seven out of eight clones carried somatic hypermutations and all bound MDA/MAA-lysine independently of protein backbone. However, clones with somatic hypermutations targeted MAA cross-linked structures rather than MDA- or MAA-hapten, while the germline-encoded synovial clone instead bound linear MDA-lysine in proteins and peptides. Binding patterns were maintained in germline converted clones. Affinity purification of polyclonal anti-MDA/MAA from patient serum revealed higher proportion of anti-MAA versus anti-MDA compared to healthy controls. In conclusion, IgG anti-MDA/MAA show distinct targeting of different molecular structures. Anti-MAA IgG has been shown to promote bone loss and osteoclastogenesis in vivo and may contribute to RA pathogenesis.
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Affiliation(s)
- Peter Sahlström
- Division of Rheumatology, Department of Medicine, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Vijay Joshua
- Division of Rheumatology, Department of Medicine, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Viktoriia Valkovskaia
- Division of Rheumatology, Department of Medicine, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Charlotte Biese
- Division of Rheumatology, Department of Medicine, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Ragnhild Stålesen
- Division of Rheumatology, Department of Medicine, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Lena Israelsson
- Division of Rheumatology, Department of Medicine, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Ákos Végvári
- Division of Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Dagmar Scheel-Toellner
- Rheumatology Research Group, Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Lars Klareskog
- Division of Rheumatology, Department of Medicine, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Monika Hansson
- Division of Rheumatology, Department of Medicine, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Aase Hensvold
- Division of Rheumatology, Department of Medicine, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden; Center for Rheumatology, Academic Specialist Center, Stockholm Health Region, Stockholm, Sweden
| | - Vivianne Malmström
- Division of Rheumatology, Department of Medicine, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Caroline Grönwall
- Division of Rheumatology, Department of Medicine, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
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3
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Yi X, Wang Y, Jia Z, Hiller S, Nakamura J, Luft JC, Tian S, DeSimone JM. Retinoic Acid-Loaded Poly(lactic- co-glycolic acid) Nanoparticle Formulation of ApoB-100-Derived Peptide 210 Attenuates Atherosclerosis. J Biomed Nanotechnol 2020; 16:467-480. [PMID: 32970979 DOI: 10.1166/jbn.2020.2905] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We developed a vaccine formulation containing ApoB derived P210 peptides as autoantigens, retinoic acid (RA) as an immune enhancer, both of which were delivered using PLGA nanoparticles. The formula was used to induce an immune response in 12-week-old male Apoe-/- mice with pre-existing atherosclerotic lesions. The nanotechnology platform PRINT® was used to fabricate PLGA nanoparticles that encapsulated RA inside and adsorbed the P210 onto the particle surface. In this study, we demonstrated that immunization of Apoe-/- mice with the formulation was able to considerably attenuate atherosclerotic lesions, accompanied by increased P210 specific IgM and another oxidized lipid derived autoantigen, M2AA, specific IgG autoantibodies, and decreased the inflammatory response, as compared to the P210 group with Freund's adjuvant. Our formulation represents an exciting technology to enhance the efficacy of the P210 vaccine.
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Tian S, Nakamura J, Hiller S, Simington S, Holley DW, Mota R, Willis MS, Bultman SJ, Luft JC, DeSimone JM, Jia Z, Maeda N, Yi X. New insights into immunomodulation via overexpressing lipoic acid synthase as a therapeutic potential to reduce atherosclerosis. Vascul Pharmacol 2020; 133-134:106777. [PMID: 32750408 DOI: 10.1016/j.vph.2020.106777] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 06/17/2020] [Accepted: 07/28/2020] [Indexed: 01/24/2023]
Abstract
Atherosclerosis is a systemic chronic inflammatory disease. Many antioxidants including alpha-lipoic acid (LA), a product of lipoic acid synthase (Lias), have proven to be effective for treatment of this disease. However, the question remains whether LA regulates the immune response as a protective mechanism against atherosclerosis. We initially investigated whether enhanced endogenous antioxidant can retard the development of atherosclerosis via immunomodulation. To explore the impact of enhanced endogenous antioxidant on the retardation of atherosclerosis via immune regulation, our laboratory has recently created a double mutant mouse model, using apolipoprotein E-deficient (Apoe-/-) mice crossbred with mice overexpressing lipoic acid synthase gene (LiasH/H), designated as LiasH/HApoe-/- mice. Their littermates, Lias+/+Apoe-/- mice, served as a control. Distinct redox environments between the two strains of mice have been established and they can be used to facilitate identification of antioxidant targets in the immune response. At 6 months of age, LiasH/HApoe-/- mice had profoundly decreased atherosclerotic lesion size in the aortic sinus compared to their Lias+/+Apoe-/- littermates, accompanied by significantly enhanced numbers of regulatory T cells (Tregs) and anti-oxidized LDL autoantibody in the vascular system, and reduced T cell infiltrates in aortic walls. Our results represent a novel exploration into an environment with increased endogenous antioxidant and its ability to alleviate atherosclerosis, likely through regulation of the immune response. These outcomes shed light on a new therapeutic strategy using antioxidants to lessen atherosclerosis.
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Affiliation(s)
- Shaomin Tian
- Department of Microbiology & Immunology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Jun Nakamura
- Laboratory of Laboratory Animal Science, Graduate School of Life and Environmental Biosciences, Osaka Prefecture University, Izumisano, Japan
| | - Sylvia Hiller
- Department of Comparative Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Stephen Simington
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Darcy W Holley
- Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Roberto Mota
- Department of Comparative Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Monte S Willis
- Indiana Center for Musculoskeletal Health, Department of Pathology & Laboratory Medicine, and Krannert Institute of Cardiology and Division of Cardiology, Department of Internal Medicine, Indiana University School of Medicine, 635 Barnhill Drive, Van Nuys MS 5067, Indianapolis, IN 46202, USA
| | - Scott J Bultman
- Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - J Christopher Luft
- Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Joseph M DeSimone
- Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Zhenquan Jia
- Department of Biology, University of North Carolina at Greensboro, Greensboro, NC 27402, USA
| | - Nobuyo Maeda
- Department of Comparative Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Xianwen Yi
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA; McAllister Heart Institute, University of North Carolina, Chapel Hill, NC 27599, USA.
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5
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Nakamura J, Holley DW, Kawamoto T, Bultman SJ. The failure of two major formaldehyde catabolism enzymes (ADH5 and ALDH2) leads to partial synthetic lethality in C57BL/6 mice. Genes Environ 2020; 42:21. [PMID: 32514323 PMCID: PMC7268536 DOI: 10.1186/s41021-020-00160-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 05/07/2020] [Indexed: 12/14/2022] Open
Abstract
Background Exogenous formaldehyde is classified by the IARC as a Category 1 known human carcinogen. Meanwhile, a significant amount of endogenous formaldehyde is produced in the human body; as such, formaldehyde-derived DNA and protein adducts have been detected in animals and humans in the absence of major exogenous formaldehyde exposure. However, the toxicological effects of endogenous formaldehyde on individuals with normal DNA damage repair functions are not well understood. In this study, we attempted to generate C57BL/6 mice deficient in both Adh5 and Aldh2, which encode two major enzymes that metabolize endogenous formaldehyde, in order to understand the effects of endogenous formaldehyde on mice with normal DNA repair function. Results Due to deficiencies in both ADH5 and ALDH2, few mice survived past post-natal day 21. In fact, the survival of pups within the first few days after birth was significantly decreased. Remarkably, two Aldh2 -/- /Adh5 -/- mice survived for 25 days after birth, and we measured their total body weight and organ weights. The body weight of Aldh2 -/- /Adh5 -/- mice decreased significantly by almost 37% compared to the Aldh2 -/- /Adh5 +/- and Aldh2 -/- /Adh5 +/+ mice of the same litter. In addition, the absolute weight of each organ was also significantly reduced. Conclusion Mice deficient in both formaldehyde-metabolizing enzymes ADH5 and ALDH2 were found to develop partial synthetic lethality and mortality shortly after birth. This phenotype may be due to the accumulation of endogenous formaldehyde. No serious phenotype has been reported in people with dysfunctional, dominant-negative ALDH2*2 alleles, but it has been reported that they may be highly susceptible to osteoporosis and neurodegenerative diseases. It is important to further investigate these diseases in individuals with ALDH2*2 alleles, including an association with decreased metabolism, and thus accumulation, of formaldehyde.
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Affiliation(s)
- Jun Nakamura
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC USA.,Laboratory of Laboratory Animal Science, Graduate School of Life and Environmental Biosciences, Osaka Prefecture University, Izumisano, Osaka, Japan
| | - Darcy W Holley
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC USA
| | - Toshihiro Kawamoto
- Department of Environmental Health, University of Occupational and Environmental Health, Kitakyushu, Fukuoka, Japan
| | - Scott J Bultman
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC USA
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Nakamura J, Nakamura M. DNA-protein crosslink formation by endogenous aldehydes and AP sites. DNA Repair (Amst) 2020; 88:102806. [PMID: 32070903 DOI: 10.1016/j.dnarep.2020.102806] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 01/22/2020] [Accepted: 01/22/2020] [Indexed: 12/19/2022]
Abstract
Covalent binding between proteins and a DNA strand produces DNA-protein crosslinks (DPC). DPC are one of the most deleterious types of DNA damage, leading to the blockage of DNA replication and transcription. Both DNA lesions and endogenous products with carbonyl functional groups can produce DPC in genomic DNA under normal physiological conditions. For example, formaldehyde, the most abundant endogenous human carcinogen, and apurinic/apyrimidinic (AP) sites, the most common type of endogenous DNA lesions, has been shown to crosslink proteins and/or DNA through their carbonyl functional groups. Unfortunately, compared to other types of DNA damage, DPC have been less studied and understood. However, a recent advancement has allowed researchers to determine accurate yields of various DNA lesions including formaldehyde-derived DPC with high sensitivity and specificity, paving the way for new developments in this field of research. Here, we review the current literature and remaining unanswered questions on DPC formation by endogenous formaldehyde and various aldehydic 2-deoxyribose lesions.
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Affiliation(s)
- Jun Nakamura
- Laboratory of Laboratory Animal Science, Graduate School of Life and Environmental Biosciences, Osaka Prefecture University, Izumisano, Osaka, Japan.
| | - Mai Nakamura
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Zeng Z, Cao B, Guo X, Li W, Li S, Chen J, Zhou W, Zheng C, Wei Y. Apolipoprotein B-100 peptide 210 antibody inhibits atherosclerosis by regulation of macrophages that phagocytize oxidized lipid. Am J Transl Res 2018; 10:1817-1828. [PMID: 30018722 PMCID: PMC6038070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 05/14/2018] [Indexed: 06/08/2023]
Abstract
Immunization with peptides derived from apolipoprotein B-100 (ApoB-100) has been shown to ameliorate atherosclerosis in apolipoprotein E knockout (ApoE-/-) mice. However, the exact mechanism underlying the therapeutic effects remains elusive. To shed light on this mechanism, we immunized ApoE-/- mice that were fed a Western diet with either malondialdehyde-modified ApoB-100 peptide 210 (P210) emulsified in Freund's adjuvant or anti-malondialdehyde-modified P210 antibody (P210-Ab). Mice immunized with Freund's adjuvant or bovine serum albumin served as controls. Macrophages were incubated in vitro with oxidized low-density lipoprotein (ox-LDL) or ox-LDL plus P210-Ab. Our results show that P210-Ab promoted cholesterol efflux, inhibited lipid accumulation in vitro, and reduced plasma levels of high-sensitivity C-reactive protein (hsCRP), monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6). Furthermore, dramatically increased the expression of Fc receptors (FcR) on peripheral blood mononuclear macrophages, suggesting that the mechanism of phagocytosis of ox-LDL by mononuclear macrophages may rely more on FcR than the cluster of differentiation 36 (CD36) scavenger receptor with P210-Ab. Both in vitro and in vivo, P210-Ab triggered the promoter of ATP-binding cassette transporter A1 (ABCA1) to increase peroxisome proliferator-activated receptor alpha (α) activity and inhibit the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway. In addition, P210-Ab significantly attenuated macrophage infiltration and markedly improved the stability of atheromatous plaque. In conclusion, the anti-atherosclerotic effect of P210-Ab is related to its preferential inhibition of inflammation and reversion of cholesterol transportation by altering the pathway by which macrophages phagocytize ox-LDL.
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Affiliation(s)
- Zhuanglin Zeng
- Laboratory of Cardiovascular Immunology, Key Laboratory of Molecular Targeted Therapies of The Ministry of Education, Institute of Cardiology, Union Hospital, Tongji Medical College of Huazhong University of Science and TechnologyWuhan 430022, Hubei, China
| | - Bingxin Cao
- Laboratory of Cardiovascular Immunology, Key Laboratory of Molecular Targeted Therapies of The Ministry of Education, Institute of Cardiology, Union Hospital, Tongji Medical College of Huazhong University of Science and TechnologyWuhan 430022, Hubei, China
| | - Xiaopeng Guo
- Department of Interventional Radiology, Union Hospital, Tongji Medical College of Huazhong University of Science and TechnologyWuhan 430022, Hubei, China
| | - Weijuan Li
- Laboratory of Cardiovascular Immunology, Key Laboratory of Molecular Targeted Therapies of The Ministry of Education, Institute of Cardiology, Union Hospital, Tongji Medical College of Huazhong University of Science and TechnologyWuhan 430022, Hubei, China
| | - Songhai Li
- Laboratory of Cardiovascular Immunology, Key Laboratory of Molecular Targeted Therapies of The Ministry of Education, Institute of Cardiology, Union Hospital, Tongji Medical College of Huazhong University of Science and TechnologyWuhan 430022, Hubei, China
| | - Juan Chen
- Laboratory of Cardiovascular Immunology, Key Laboratory of Molecular Targeted Therapies of The Ministry of Education, Institute of Cardiology, Union Hospital, Tongji Medical College of Huazhong University of Science and TechnologyWuhan 430022, Hubei, China
| | - Wenping Zhou
- Laboratory of Cardiovascular Immunology, Key Laboratory of Molecular Targeted Therapies of The Ministry of Education, Institute of Cardiology, Union Hospital, Tongji Medical College of Huazhong University of Science and TechnologyWuhan 430022, Hubei, China
| | - Chuansheng Zheng
- Department of Interventional Radiology, Union Hospital, Tongji Medical College of Huazhong University of Science and TechnologyWuhan 430022, Hubei, China
| | - Yumiao Wei
- Laboratory of Cardiovascular Immunology, Key Laboratory of Molecular Targeted Therapies of The Ministry of Education, Institute of Cardiology, Union Hospital, Tongji Medical College of Huazhong University of Science and TechnologyWuhan 430022, Hubei, China
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Immunization with gingipain A hemagglutinin domain of Porphyromonas gingivalis induces IgM antibodies binding to malondialdehyde-acetaldehyde modified low-density lipoprotein. PLoS One 2018; 13:e0191216. [PMID: 29329335 PMCID: PMC5766137 DOI: 10.1371/journal.pone.0191216] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 12/29/2017] [Indexed: 12/12/2022] Open
Abstract
Treatment of periodontitis has beneficial effects on systemic inflammation markers that relate to progression of atherosclerosis. We aimed to investigate whether immunization with A hemagglutinin domain (Rgp44) of Porphyromonas gingivalis (Pg), a major etiologic agent of periodontitis, would lead to an antibody response cross-reacting with oxidized low-density lipoprotein (OxLDL) and how it would affect the progression of atherosclerosis in low-density lipoprotein receptor-deficient (LDLR-/-) mice. The data revealed a prominent IgM but not IgG response to malondialdehyde-acetaldehyde modified LDL (MAA-LDL) after Rgp44 and Pg immunizations, implying that Rgp44/Pg and MAA adducts may share cross-reactive epitopes that prompt IgM antibody production and consequently confer atheroprotection. A significant negative association was observed between atherosclerotic lesion and plasma IgA to Rgp44 in Rgp44 immunized mice, supporting further the anti-atherogenic effect of Rgp44 immunization. Plasma IgA levels to Rgp44 and to Pg in both Rgp44- and Pg-immunized mice were significantly higher than those in saline control, suggesting that IgA to Rgp44 could be a surrogate marker of immunization in Pg-immunized mice. Distinct antibody responses in plasma IgA levels to MAA-LDL, to Pg lipopolysaccharides (Pg-LPS), and to phosphocholine (PCho) were observed after Rgp44 and Pg immunizations, indicating that different immunogenic components between Rpg44 and Pg may behave differently in regard of their roles in the development of atherosclerosis. Immunization with Rgp44 also displayed atheroprotective features in modulation of plaque size through association with plasma levels of IL-1α whereas whole Pg bacteria achieved through regulation of anti-inflammatory cytokine levels of IL-5 and IL-10. The present study may contribute to refining therapeutic approaches aiming to modulate immune responses and inflammatory/anti-inflammatory processes in atherosclerosis.
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Evidence that endogenous formaldehyde produces immunogenic and atherogenic adduct epitopes. Sci Rep 2017; 7:10787. [PMID: 28883613 PMCID: PMC5589919 DOI: 10.1038/s41598-017-11289-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 08/23/2017] [Indexed: 01/21/2023] Open
Abstract
Endogenous formaldehyde is abundantly present in our bodies, at around 100 µM under normal conditions. While such high steady state levels of formaldehyde may be derived by enzymatic reactions including oxidative demethylation/deamination and myeloperoxidation, it is unclear whether endogenous formaldehyde can initiate and/or promote diseases in humans. Here, we show that fluorescent malondialdehyde-formaldehyde (M2FA)-lysine adducts are immunogenic without adjuvants in mice. Natural antibody titers against M2FA are elevated in atherosclerosis-prone mice. Staining with an antibody against M2FA demonstrated that M2FA is present in plaque found on the aortic valve of ApoE−/− mice. To mimic inflammation during atherogenesis, human myeloperoxidase was incubated with glycine, H2O2, malondialdehyde, and a lysine analog in PBS at a physiological temperature, which resulted in M2FA generation. These results strongly suggest that the 1,4-dihydropyridine-type of lysine adducts observed in atherosclerosis lesions are likely produced by endogenous formaldehyde and malondialdehyde with lysine. These highly fluorescent M2FA adducts may play important roles in human inflammatory and degenerative diseases.
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