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Ko EJ, Song KS, Ock MS, Choi YH, Kim S, Kim HS, Cha HJ. Expression profiles of human endogenous retrovirus (HERV)-K and HERV-R Env proteins in various cancers. BMB Rep 2021. [PMID: 33691904 PMCID: PMC8328825 DOI: 10.5483/bmbrep.2021.54.7.246] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The vertebrate genome contains an endogenous retrovirus that has been inherited from the past millions of years. Although approximately 8% of human chromosomal DNA consists of sequences derived from human endogenous retrovirus (HERV) fragments, most of the HERVs are currently inactive and non-infectious due to recombination, deletions, and mutations after insertion into the host genome. Several studies suggested that Human endogenous retroviruses (HERVs) factors are significantly related to certain cancers. However, only limited studies have been conducted to analyze the expression of HERV derived elements at protein levels in certain cancers. Herein, we analyzed the expression profiles of HERV-K envelope (Env) and HERV-R Env proteins in eleven different kinds of cancer tissues. Furthermore, the expression patterns of both protein and correlation with various clinical data in each tissue were analyzed. The expressions of both HERV-K Env and HERV-R Env protein were identified to be significantly high in most of the tumors compared with normal surrounding tissues. Correlations between HERV Env expressions and clinical investigations varied depending on the HERV types and cancers. Overall expression patterns of HERV-K Env and HERV-R Env proteins were different in every individual but a similar pattern of expressions was observed in the same individual. These results demonstrate the expression profiles of HERV-K and HERV-R Env proteins in various cancer tissues and provide a good reference for the association of endogenous retroviral Env proteins in the progression of various cancers. Furthermore, the results elucidate the relationship between HERV-Env expression and the clinical significance of certain cancers.
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Affiliation(s)
- Eun-Ji Ko
- Department of Parasitology and Genetics, Kosin University College of Medicine, Busan 49267, Korea
- Department of Biological Sciences, Pusan National University, Busan 46241, Korea
| | - Kyoung Seob Song
- Department of Physiology, Kosin University College of Medicine, Busan 49267, Korea
| | - Mee Sun Ock
- Department of Parasitology and Genetics, Kosin University College of Medicine, Busan 49267, Korea
| | - Yung Hyun Choi
- Department of Biochemistry, College of Oriental Medicine, Dongeui University, Busan 47227, Korea
| | - Suhkmann Kim
- Department of Chemistry, College of Natural Sciences, Pusan National University, Busan 46241, Korea
| | - Heui-Soo Kim
- Department of Biological Sciences, Pusan National University, Busan 46241, Korea
| | - Hee-Jae Cha
- Department of Parasitology and Genetics, Kosin University College of Medicine, Busan 49267, Korea
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Ko EJ, Song KS, Ock MS, Choi YH, Kim S, Kim HS, Cha HJ. Expression profiles of human endogenous retrovirus (HERV)-K and HERV-R Env proteins in various cancers. BMB Rep 2021; 54:368-373. [PMID: 33691904 PMCID: PMC8328825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 12/08/2020] [Accepted: 02/21/2021] [Indexed: 04/04/2024] Open
Abstract
The vertebrate genome contains an endogenous retrovirus that has been inherited from the past millions of years. Although approximately 8% of human chromosomal DNA consists of sequences derived from human endogenous retrovirus (HERV) fragments, most of the HERVs are currently inactive and noninfectious due to recombination, deletions, and mutations after insertion into the host genome. Several studies suggested that Human endogenous retroviruses (HERVs) factors are significantly related to certain cancers. However, only limited studies have been conducted to analyze the expression of HERV derived elements at protein levels in certain cancers. Herein, we analyzed the expression profiles of HERV-K envelope (Env) and HERV-R Env proteins in eleven different kinds of cancer tissues. Furthermore, the expression patterns of both protein and correlation with various clinical data in each tissue were analyzed. The expressions of both HERV-K Env and HERV-R Env protein were identified to be significantly high in most of the tumors compared with normal surrounding tissues. Correlations between HERV Env expressions and clinical investigations varied depending on the HERV types and cancers. Overall expression patterns of HERV-K Env and HERV-R Env proteins were different in every individual but a similar pattern of expressions was observed in the same individual. These results demonstrate the expression profiles of HERV-K and HERV-R Env proteins in various cancer tissues and provide a good reference for the association of endogenous retroviral Env proteins in the progression of various cancers. Furthermore, the results elucidate the relationship between HERV-Env expression and the clinical significance of certain cancers. [BMB Reports 2021; 54(7): 368-373].
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Affiliation(s)
- Eun-Ji Ko
- Department of Parasitology and Genetics, Busan 46241, Korea
- Department of Biological Sciences, Busan 46241, Korea
| | - Kyoung Seob Song
- Department of Physiology, Kosin University College of Medicine, Busan 49267, Korea
| | - Mee Sun Ock
- Department of Parasitology and Genetics, Busan 46241, Korea
| | - Yung Hyun Choi
- Department of Biochemistry, College of Oriental Medicine, Dongeui University, Busan 47227, Korea
| | - Suhkmann Kim
- Department of Chemistry, College of Natural Sciences, Pusan National University, Busan 46241, Korea
| | - Heui-Soo Kim
- Department of Biological Sciences, Busan 46241, Korea
| | - Hee-Jae Cha
- Department of Parasitology and Genetics, Busan 46241, Korea
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Mastrangelo G, Pavanello S, Fadda E, Buja A, Fedeli U. Yellow fever vaccine 17D administered to healthy women aged between 40 and 54 years halves breast cancer risk: an observational study. Eur J Cancer Prev 2018; 27:303-309. [PMID: 27870643 PMCID: PMC6012044 DOI: 10.1097/cej.0000000000000333] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 10/25/2016] [Indexed: 12/11/2022]
Abstract
Transcripts of human endogenous retrovirus K are expressed in most breast cancers (BCs). Yellow fever vaccine 17D (YFV) expresses a protein with a closely homologous epitope. Cross-reactive immunity could hypothetically inhibit BC growth at least in women aged around 50 years at diagnosis, in whom the prognosis of BC was found to be better than that in women younger or older. A cohort of 12 804 women who received YFV in the Veneto Region, Italy, was divided into two subcohorts according to age at vaccination and followed up through the Veneto Tumor Registry. The time since vaccination until cancer incidence was categorized (≤1.9; 2-3.9; 4-5.9; 6-7.9; 8-10.9; ≥11 years) and, using the lowest class as a reference, the incidence rate ratio for BC with a 95% confidence interval and P-value was estimated by Poisson regression in each time since vaccination class, adjusting for age and calendar period. In 3140 women vaccinated at 40-54 years of age, YFV administration resulted in a protective effect of long duration slowly fading over time with a U-shaped pattern of response. Overall, BC risk was reduced by about 50% (incidence rate ratio=0.46; 95% confidence interval=0.26-0.83; P=0.009) 2 years after vaccination. Cross-reactive antigens could not be the mechanism because no protection was observed in women vaccinated before 40 or after 54 years of age. BC cells in a microscopic stage of disease can be destroyed or severely damaged by YFV if BC is not very aggressive. To prove that treatment is truly effective, a placebo-controlled double-blind trial should be conducted.
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Affiliation(s)
| | | | | | | | - Ugo Fedeli
- Regional Epidemiology Service, Veneto Region, Padova, Italy
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Contribution of Syncytins and Other Endogenous Retroviral Envelopes to Human Placenta Pathologies. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2017; 145:111-162. [DOI: 10.1016/bs.pmbts.2016.12.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Krone B, Kölmel KF, Grange JM. The biography of the immune system and the control of cancer: from St Peregrine to contemporary vaccination strategies. BMC Cancer 2014; 14:595. [PMID: 25128300 PMCID: PMC4141110 DOI: 10.1186/1471-2407-14-595] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Accepted: 08/12/2014] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND The historical basis and contemporary evidence for the use of immune strategies for prevention of malignancies are reviewed. Emphasis is focussed on the Febrile Infections and Melanoma (FEBIM) study on melanoma and on malignancies that seem to be related to an overexpression of human endogenous retrovirus K (HERV-K). DISCUSSION It is claimed that, as a result of recent observational studies, measures for prevention of some malignancies such as melanoma and certain forms of leukaemia are already at hand: vaccination with Bacille Calmette-Guérin (BCG) of new-borns and vaccination with the yellow fever 17D (YFV) vaccine of adults. While the evidence of their benefit for prevention of malignancies requires substantiation, the observations that vaccinations with BCG and/or vaccinia early in life improved the outcome of patients after surgical therapy of melanoma are of practical relevance as the survival advantage conferred by prior vaccination is greater than any contemporary adjuvant therapy. SUMMARY The reviewed findings open a debate as to whether controlled vaccination studies should be conducted in patients and/or regions for whom/where they are needed most urgently. A study proposal is made and discussed. If protection is confirmed, the development of novel recombinant vaccines with wider ranges of protection based, most likely, on BCG, YFV or vaccinia, could be attempted.
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Affiliation(s)
- Bernd Krone
- />Institute of Virology of Georg August University Göttingen, Göttingen, Germany
- />Medical Laboratory, Kurt-Reuber-Haus, Herkulesstraße 34a, 34119 Kassel, Germany
| | - Klaus F Kölmel
- />Dermatologic Clinic of Georg August University Göttingen, Göttingen, Germany
| | - John M Grange
- />London Clinic Cancer Centre B2, 22 Devonshire Place, London, W1G 6JA UK
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Downey RF, Sullivan FJ, Wang-Johanning F, Ambs S, Giles FJ, Glynn SA. Human endogenous retrovirus K and cancer: Innocent bystander or tumorigenic accomplice? Int J Cancer 2014; 137:1249-57. [PMID: 24890612 PMCID: PMC6264888 DOI: 10.1002/ijc.29003] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 05/02/2014] [Accepted: 05/09/2014] [Indexed: 12/20/2022]
Abstract
Harbored as relics of ancient germline infections, human endogenous retroviruses (HERVs) now constitute up to 8% of our genome. A proportion of this sequence has been co-opted for molecular and cellular processes, beneficial to human physiology, such as the fusogenic activity of the envelope protein, a vital component of placentogenesis. However, the discovery of high levels of HERV-K mRNA and protein and even virions in a wide array of cancers has revealed that HERV-K may be playing a more sinister role–a role as an etiological agent in cancer itself. Whether the presence of this retroviral material is simply an epiphenomenon, or an actual causative factor, is a hotly debated topic. This review will summarize the current state of knowledge regarding HERV-K and cancer and attempt to outline the potential mechanisms by which HERV-K could be involved in the onset and promotion of carcinogenesis.
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Affiliation(s)
- Ronan F Downey
- Prostate Cancer Institute, National University of Ireland Galway, Galway, Ireland
| | - Francis J Sullivan
- Prostate Cancer Institute, National University of Ireland Galway, Galway, Ireland.,Department of Radiation Oncology, Galway University Hospitals, Galway, Ireland
| | | | - Stefan Ambs
- Laboratory of Human Carcinogenesis, National Cancer Institute, Bethesda, MD
| | - Francis J Giles
- Prostate Cancer Institute, National University of Ireland Galway, Galway, Ireland.,HRB Clinical Research Facilities Galway & Dublin, National University of Ireland Galway and Trinity College Dublin, Galway, Ireland
| | - Sharon A Glynn
- Prostate Cancer Institute, National University of Ireland Galway, Galway, Ireland
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Douville RN, Nath A. Human endogenous retroviruses and the nervous system. HANDBOOK OF CLINICAL NEUROLOGY 2014; 123:465-85. [PMID: 25015500 DOI: 10.1016/b978-0-444-53488-0.00022-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Renée N Douville
- Department of Microbiology, University of Winnipeg, Winnipeg, Manitoba, Canada
| | - Avindra Nath
- Section of Infections of the Nervous System, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD, USA.
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Krone B, Grange JM. Is a hypothetical melanoma-like neuromelanin the underlying factor essential for the aetiopathogenesis and clinical manifestations of multiple sclerosis? BMC Neurol 2013; 13:91. [PMID: 23865526 PMCID: PMC3723426 DOI: 10.1186/1471-2377-13-91] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 07/11/2013] [Indexed: 01/12/2023] Open
Abstract
Background Multiple sclerosis (MS) has undergone a significant increase in incidence in the industrialised nations over the last 130 years. Changing environmental factors, possibly infections or a lack of or altered timing of them, determine the prevalence of the disease. Although a plethora of aetiological factors, clearly evident in a group of children with MS, appear relevant, there may nevertheless be a single factor essential for the aetiopathogenesis and clinical manifestation of MS. Description and discussion This hitherto unknown factor is postulated to be a ‘melanoma-like neuromelanin’ (MLN) dependent on the activation of a gene for syncytin-1. An involvement of MLN could explain the diverse findings in the epidemiology, immunology and pathology of MS, requiring a consideration of a complex infectious background, the human leucocyte antigens, as well as cosmic radiation causing geomagnetic disturbances, vitamin D deficiency, smoking, and lower levels of uric acid. Summary In principle, the MLN-based concept is a unifying one, capable of explaining a number of characteristics of the disease. To date, MLN has not been addressed in studies on MS and future work will need to be done on human patients, as there is little or no neuromelanin (the precursor of MLN) in the animals used as experimental models in the study of MS.
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Affiliation(s)
- Bernd Krone
- Institute of Virology, University of Göttingen, Kreuzbergring 57, 37075 Göttingen, Germany.
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Manghera M, Douville RN. Endogenous retrovirus-K promoter: a landing strip for inflammatory transcription factors? Retrovirology 2013; 10:16. [PMID: 23394165 PMCID: PMC3598470 DOI: 10.1186/1742-4690-10-16] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Accepted: 02/01/2013] [Indexed: 12/24/2022] Open
Abstract
Humans are symbiotic organisms; our genome is populated with a substantial number of endogenous retroviruses (ERVs), some remarkably intact, while others are remnants of their former selves. Current research indicates that not all ERVs remain silent passengers within our genomes; re-activation of ERVs is often associated with inflammatory diseases. ERVK is the most recently endogenized and transcriptionally active ERV in humans, and as such may potentially contribute to the pathology of inflammatory disease. Here, we showcase the transcriptional regulation of ERVK. Expression of ERVs is regulated in part by epigenetic mechanisms, but also depends on transcriptional regulatory elements present within retroviral long terminal repeats (LTRs). These LTRs are responsive to both viral and cellular transcription factors; and we are just beginning to appreciate the full complexity of transcription factor interaction with the viral promoter. In this review, an exploration into the inflammatory transcription factor sites within the ERVK LTR will highlight the possible mechanisms by which ERVK is induced in inflammatory diseases.
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Affiliation(s)
- Mamneet Manghera
- Department of Biology, The University of Winnipeg, Winnipeg, MB, Canada
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Cegolon L, Salata C, Weiderpass E, Vineis P, Palù G, Mastrangelo G. Human endogenous retroviruses and cancer prevention: evidence and prospects. BMC Cancer 2013; 13:4. [PMID: 23282240 PMCID: PMC3557136 DOI: 10.1186/1471-2407-13-4] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 12/02/2012] [Indexed: 12/05/2022] Open
Abstract
Background Cancer is a significant and growing problem worldwide. While this increase may, in part, be attributed to increasing longevity, improved case notifications and risk-enhancing lifestyle (such as smoking, diet and obesity), hygiene-related factors resulting in immuno-regulatory failure may also play a major role and call for a revision of vaccination strategies to protect against a range of cancers in addition to infections. Discussion Human endogenous retroviruses (HERVs) are a significant component of a wider family of retroelements that constitutes part of the human genome. They were originated by the integration of exogenous retroviruses into the human genome millions of years ago. HERVs are estimated to comprise about 8% of human DNA and are ubiquitous in somatic and germinal tissues. Physiologic and pathologic processes are influenced by some biologically active HERV families. HERV antigens are only expressed at low levels by the host, but in circumstances of inappropriate control their genes may initiate or maintain pathological processes. Although the precise mechanism leading to abnormal HERVs gene expression has yet to be clearly elucidated, environmental factors seem to be involved by influencing the human immune system. HERV-K expression has been detected in different types of tumors. Among the various human endogenous retroviral families, the K series was the latest acquired by the human species. Probably because of its relatively recent origin, the HERV-K is the most complete and biologically active family. The abnormal expression of HERV-K seemingly triggers pathological processes leading to melanoma onset, but also contributes to the morphological and functional cellular modifications implicated in melanoma maintenance and progression. The HERV-K-MEL antigen is encoded by a pseudo-gene incorporated in the HERV-K env-gene. HERV-K-MEL is significantly expressed in the majority of dysplastic and normal naevi, as well as other tumors like sarcoma, lymphoma, bladder and breast cancer. An amino acid sequence similar to HERV-K-MEL, recognized to cause a significant protective effect against melanoma, is shared by the antigenic determinants expressed by some vaccines such as BCG, vaccinia virus and the yellow fever virus. HERV-K are also reactivated in the majority of human breast cancers. Monoclonal and single-chain antibodies against the HERV-K Env protein recently proved capable of blocking the proliferation of human breast cancer cells in vitro, inhibiting tumor growth in mice bearing xenograft tumors. Summary A recent epidemiological study provided provisional evidence of how melanoma risk could possibly be reduced if the yellow fever virus vaccine (YFV) were received at least 10 years before, possibly preventing tumor initiation rather than culling melanoma cells already compromised. Further research is recommended to confirm the temporal pattern of this protection and eliminate/attenuate the potential role of relevant confounders as socio-economic status and other vaccinations. It appears also appropriate to examine the potential protective effect of YFV against other malignancies expressing high levels of HERV-K antigens, namely breast cancer, sarcoma, lymphoma and bladder cancer. Tumor immune-therapy, as described for the monoclonal antibodies against breast cancer, is indeed considered more complex and less advantageous than immune-prevention. Cellular immunity possibly triggered by vaccines as for YFV might also be involved in anti-cancer response, in addition to humoral immunity.
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Affiliation(s)
- Luca Cegolon
- Department of Molecular Medicine, Padua University, Padua, Italy.
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Nissen KK, Laska MJ, Hansen B, Pedersen FS, Nexø BA. No additional copies of HERV-Fc1 in the germ line of multiple sclerosis patients. Virol J 2012; 9:188. [PMID: 22958517 PMCID: PMC3459695 DOI: 10.1186/1743-422x-9-188] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 08/29/2012] [Indexed: 11/13/2022] Open
Abstract
Background Human endogenous retroviruses (HERVs) are suspected to play a role in the development of multiple sclerosis (MS). This suspicion has in part been based on increased expression of viral RNA or proteins or antibodies targeting retroviral products in MS patients. Recently, our group provided genetic evidence for association between the endogenous retrovirus HERV-Fc1 and MS, suggesting that HERV-Fc1 plays a role in this multifactorial disease. We have found increased expression of HERV-Fc1 in MS patients suffering from recent attack, but the underlying mechanism for association is still unknown. Findings Evidence from animal models indicates that ERV implication in the pathogenesis of diseases can be a result of extra copies of the virus in the germ line. Therefore, we investigated the genome of 81 individuals, 74 patients with MS and 7 healthy controls, by means of Southern blotting, for presence of extra HERV-Fc1 copies. The known insertion at the Xq21.33 position was readily detectable, but no additional insertions in other genomic contexts could be identified in any studied individuals. This substantiates our previous copy-number PCR findings of a 2:1 ratio of HERV-Fc1 DNA between women and men, as expected from the X-chromosome location; there was no difference between patient and control individuals. Conclusions No additional germ line copies of HERV-Fc1 could be identified, precluding such copies to underlie the association between this provirus and multiples sclerosis.
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Affiliation(s)
- Kari K Nissen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.
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Ponsonby AL, Hughes AM, Lucas RM. The ‘hygiene hypothesis’ and the development of multiple sclerosis. Neurodegener Dis Manag 2011. [DOI: 10.2217/nmt.11.38] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
SUMMARY We review evidence linking inadequate microbial exposure in early life to the development of multiple sclerosis (MS). There is some supportive, but not conclusive evidence for a role of a hygienic environment in early life and MS. Population-level studies of MS are consistent with the hygiene hypothesis but are limited by methodological issues. Late infection with Epstein–Barr virus (EBV) has been prospectively associated with MS and must be incorporated into any model where the hygiene hypothesis is implicated in the development of MS. One possibility is that inadequate microbial exposure in early life contributes to a dysregulated host immune response to EBV. Two areas of particular interest include the potential role for helminthic infection in biasing the human immune response away from the immune profile associated with MS and also the role of microbial exposure in training the development of the EBV-specific immune response.
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Affiliation(s)
- Anne-Louise Ponsonby
- Murdoch Childrens Research Institute, The Royal Children’s Hospital, Parkville Victoria 3052, Melbourne, Australia
| | - Ann Maree Hughes
- National Centre for Epidemiology & Population Health, The Australian National University, Canberra, Australia
| | - Robyn Marjorie Lucas
- National Centre for Epidemiology & Population Health, The Australian National University, Canberra, Australia
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George M, Schwecke T, Beimforde N, Hohn O, Chudak C, Zimmermann A, Kurth R, Naumann D, Bannert N. Identification of the protease cleavage sites in a reconstituted Gag polyprotein of an HERV-K(HML-2) element. Retrovirology 2011; 8:30. [PMID: 21554716 PMCID: PMC3114732 DOI: 10.1186/1742-4690-8-30] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Accepted: 05/09/2011] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND The human genome harbors several largely preserved HERV-K(HML-2) elements. Although this retroviral family comes closest of all known HERVs to producing replication competent virions, mutations acquired during their chromosomal residence have rendered them incapable of expressing infectious particles. This also holds true for the HERV-K113 element that has conserved open reading frames (ORFs) for all its proteins in addition to a functional LTR promoter. Uncertainty concerning the localization and impact of post-insertional mutations has greatly hampered the functional characterization of these ancient retroviruses and their proteins. However, analogous to other betaretroviruses, it is known that HERV-K(HML-2) virions undergo a maturation process during or shortly after release from the host cell. During this process, the subdomains of the Gag polyproteins are released by proteolytic cleavage, although the nature of the mature HERV-K(HML-2) Gag proteins and the exact position of the cleavage sites have until now remained unknown. RESULTS By aligning the amino acid sequences encoded by the gag-pro-pol ORFs of HERV-K113 with the corresponding segments from 10 other well-preserved human specific elements we identified non-synonymous post-insertional mutations that have occurred in this region of the provirus. Reversion of these mutations and a partial codon optimization facilitated the large-scale production of maturation-competent HERV-K113 virus-like particles (VLPs). The Gag subdomains of purified mature VLPs were separated by reversed-phase high-pressure liquid chromatography and initially characterized using specific antibodies. Cleavage sites were identified by mass spectrometry and N-terminal sequencing and confirmed by mutagenesis. Our results indicate that the gag gene product Pr74Gag of HERV-K(HML-2) is processed to yield p15-MA (matrix), SP1 (spacer peptide of 14 amino acids), p15, p27-CA (capsid), p10-NC (nucleocapsid) and two C-terminally encoded glutamine- and proline-rich peptides, QP1 and QP2, spanning 23 and 19 amino acids, respectively. CONCLUSIONS Expression of reconstituted sequences of original HERV elements is an important tool for studying fundamental aspects of the biology of these ancient viruses. The analysis of HERV-K(HML-2) Gag processing and the nature of the mature Gag proteins presented here will facilitate further studies of the discrete functions of these proteins and of their potential impact on the human host.
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Affiliation(s)
- Maja George
- Center for HIV and Retrovirology, Robert Koch Institute, Nordufer 20, 13353 Berlin, Germany
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Krone B, Grange JM. Paradigms in multiple sclerosis: time for a change, time for a unifying concept. Inflammopharmacology 2011; 19:187-95. [PMID: 21547536 PMCID: PMC3127006 DOI: 10.1007/s10787-011-0084-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2011] [Accepted: 04/09/2011] [Indexed: 12/12/2022]
Abstract
It has recently been suggested that, rather than being an autoimmune disease, multiple sclerosis (MS) is an example of a neurocristopathy, a pathological process resulting from a faulty development of the neural crest. Whilst several characteristics of the disease suggest a neurocristopathy, other aetiological factors require consideration, including hygiene-related factors that alter the immune responses to common pathogens resulting in an eclipse of immune reactivity that could protect against MS, the possible role of human endogenous retroviruses (HERVs) in pathogenesis and autoimmune phenomena, HLA polymorphism, vitamin D levels before and after birth and immune repair mechanisms. A postulated aetiological factor in MS, associated with altered vitamin D metabolism and abnormal HERV expression, is a long-lasting disturbed redox regulation in the biosynthesis of a melanoma-like melanin pigment. Although intensive further studies on melanin pigments in nerve tissue in MS are required, the known properties of a pathological form of such pigments in melanoma could explain a number of observations in MS, including the impact of light, UV-light, and vitamin D, and could explain the clinical manifestations of MS on the basis of an oscillating process of oxidative charge and discharge of the pigments and a threshold phenomenon with a change of the quasi-catalytic function of the pigment from destroying reactive oxygen radicals or species to transforming them to more harmful long-persisting highly reactive species. Taken together with the consequences of an adaptive process in partly demyelinated neurons, resulting in an increase in number of mitochondria, and the impact of stressful life events, these conditions are necessary and sufficient to explain the disease process of MS with its spatial (plaques) and temporal (attacks and remissions) characteristics. This suggested unifying concept of the pathogenesis of MS may open perspectives for prevention, diagnosis and therapy. In particular, prevention may be achieved by vaccinating against Epstein-Barr virus in early childhood.
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Affiliation(s)
- Bernd Krone
- Institute of Virology, Centre for Hygiene and Human Genetics, University of Göttingen, Kreuzbergring 57, 37075 Göttingen, Germany
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Krone B, Grange JM. Multiple sclerosis: are protective immune mechanisms compromised by a complex infectious background? Autoimmune Dis 2010; 2011:708750. [PMID: 21197482 PMCID: PMC3010623 DOI: 10.4061/2011/708750] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Revised: 10/07/2010] [Accepted: 11/18/2010] [Indexed: 11/20/2022] Open
Abstract
The immunological background of multiple sclerosis (MS) manifests as an altered reactivity against a diverse range of infections, particularly with the Epstein-Barr virus. Although this could be only an epiphenomenon of a more generalised dysfunction of the immune system in MS, it is also possible that a complex infectious background forms the basis of a specific immune dysregulation finally causing the disease. It is thus suggested that the complex infectious background bears the key for an understanding of the immune pathogenesis of the disease. It appears probable that improved standards of hygiene cause regulatory defects in the immune system, allowing the abnormal expression of human endogenous retroviral (HERV) genes. On the basis of epidemiological observations we describe how a failure of expansion or an eclipse of a subfraction of self-antigen-specific CD8(+) T cells mediating immune repair, and a deleterious mode of action of HERV gene products, could underlie the pathogenesis of MS.
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Affiliation(s)
- Bernd Krone
- Institute of Virology, Centre for Hygiene and Human Genetics, University of Göttingen, Kreuzbergring 57, 37075 Göttingen, Germany
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