Virologic and Immunologic Evidence Supporting an Association between HHV-6 and Hashimoto's Thyroiditis

Caselli, Elisabetta; Zatelli, Maria Chiara; Rizzo, Roberta; Benedetti, Sabrina; Martorelli, Debora; Trasforini, Giorgio; Cassai, Enzo; Uberti, Ettore C. degli; Luca, Dario Di; Dolcetti, Riccardo

doi:10.1371/journal.ppat.1002951

Cited by 129 publications

(171 citation statements)

References 49 publications

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“…Indeed, we observed the presence of infiltrating T and B lymphocytes in several CD46 transgenic mice, which further confirms the ability of HHV-6A to induce leukocyte trafficking to the brain. Recently, Hashimoto's thyroiditis has been shown to be associated with HHV-6A infection (74), and it is possible that the abundant lymphocyte infiltrates observed in this disease can be induced by HHV-6A-stimulated chemokine production, leading to further triggering of the autoimmune response.…”

Section: Discussionmentioning

confidence: 99%

Human Herpesvirus 6A Infection in CD46 Transgenic Mice: Viral Persistence in the Brain and Increased Production of Proinflammatory Chemokines via Toll-Like Receptor 9

Reynaud

Jégou

Welsch

et al. 2014

J Virol

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Human herpesvirus 6 (HHV-6) is widely spread in the human population and has been associated with several neuroinflammatory diseases, including multiple sclerosis. To develop a small-animal model of HHV-6 infection, we analyzed the susceptibility of several lines of transgenic mice expressing human CD46, identified as a receptor for HHV-6. We showed that HHV-6A (GS) infection results in the expression of viral transcripts in primary brain glial cultures from CD46-expressing mice, while HHV-6B (Z29) infection was inefficient. HHV-6A DNA persisted for up to 9 months in the brain of CD46-expressing mice but not in the nontransgenic littermates, whereas HHV-6B DNA levels decreased rapidly after infection in all mice. Persistence in the brain was observed with infectious but not heat-inactivated HHV-6A. Immunohistological studies revealed the presence of infiltrating lymphocytes in periventricular areas of the brain of HHV-6A-infected mice. Furthermore, HHV-6A stimulated the production of a panel of proinflammatory chemokines in primary brain glial cultures, including CCL2, CCL5, and CXCL10, and induced the expression of CCL5 in the brains of HHV-6A-infected mice. HHV-6A-induced production of chemokines in the primary glial cultures was dependent on the stimulation of toll-like receptor 9 (TLR9). Finally, HHV-6A induced signaling through human TLR9 as well, extending observations from the murine model to human infection. Altogether, this study presents a first murine model for HHV-6A-induced brain infection and suggests a role for TLR9 in the HHV-6A-initiated production of proinflammatory chemokines in the brain, opening novel perspectives for the study of virus-associated neuropathology. IMPORTANCEHHV-6 infection has been related to neuroinflammatory diseases; however, the lack of a suitable small-animal infection model has considerably hampered further studies of HHV-6-induced neuropathogenesis. In this study, we have characterized a new model for HHV-6 infection in mice expressing the human CD46 protein. Infection of CD46 transgenic mice with HHV-6A resulted in long-term persistence of viral DNA in the brains of infected animals and was followed by lymphocyte infiltration and upregulation of the CCL5 chemokine in the absence of clinical signs of disease. The secretion of a panel of chemokines was increased after infection in primary murine brain glial cultures, and the HHV-6-induced chemokine expression was inhibited when TLR9 signaling was blocked. These results describe the first murine model for HHV-6A-induced brain infection and suggest the importance of the TLR9 pathway in HHV-6A-initiated neuroinflammation.

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Section: Discussionmentioning

confidence: 99%

Human Herpesvirus 6A Infection in CD46 Transgenic Mice: Viral Persistence in the Brain and Increased Production of Proinflammatory Chemokines via Toll-Like Receptor 9

Reynaud

Jégou

Welsch

et al. 2014

J Virol

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“…The interaction of HHV-6A with its CD46 receptor, which is a regulator of complement activation, may cause an upregulation of this process, including deleterious lytic cell effects and an increase of the soluble form of CD46 (147). The dysfunction of HHV-6-induced immune responses leading to autoimmune processes would involve not only specific T cell responses but also NK cell-mediated activation and killing (148). All these phenomena would converge to promote release of self antigens and polyclonal activation.…”

Section: Latent Infectionmentioning

confidence: 99%

Laboratory and Clinical Aspects of Human Herpesvirus 6 Infections

2015

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SUMMARY Human herpesvirus 6 (HHV-6) is a widespread betaherpesvirus which is genetically related to human cytomegalovirus (HCMV) and now encompasses two different species: HHV-6A and HHV-6B. HHV-6 exhibits a wide cell tropism in vivo and, like other herpesviruses, induces a lifelong latent infection in humans. As a noticeable difference with respect to other human herpesviruses, genomic HHV-6 DNA is covalently integrated into the subtelomeric region of cell chromosomes (ciHHV-6) in about 1% of the general population. Although it is infrequent, this may be a confounding factor for the diagnosis of active viral infection. The diagnosis of HHV-6 infection is performed by both serologic and direct methods. The most prominent technique is the quantification of viral DNA in blood, other body fluids, and organs by means of real-time PCR. Many active HHV-6 infections, corresponding to primary infections, reactivations, or exogenous reinfections, are asymptomatic. However, the virus may be the cause of serious diseases, particularly in immunocompromised individuals. As emblematic examples of HHV-6 pathogenicity, exanthema subitum, a benign disease of infancy, is associated with primary infection, whereas further virus reactivations can induce severe encephalitis cases, particularly in hematopoietic stem cell transplant recipients. Generally speaking, the formal demonstration of the causative role of HHV-6 in many acute and chronic human diseases is difficult due to the ubiquitous nature of the virus, chronicity of infection, existence of two distinct species, and limitations of current investigational tools. The antiviral compounds ganciclovir, foscarnet, and cidofovir are effective against active HHV-6 infections, but the indications for treatment, as well as the conditions of drug administration, are not formally approved to date. There are still numerous pending questions about HHV-6 which should stimulate future research works on the pathophysiology, diagnosis, and therapy of this remarkable human virus.

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“…Before each experiment, cells were incubated in 0.5% HS medium for 48 h followed by a 24-h incubation in 10% HS medium. The human thyroid follicular epithelial cell line, Nthy-ori 3-1 (ECACC, Salisbury, UK), was maintained in RPMI-1640 medium (Invitrogen) supplemented with 10% fetal bovine serum (FBS) (LGC Standards) and antibiotic antimycotic (EuroClone) as described previously (Caselli et al 2012).…”

Section: Cell Culturementioning

confidence: 99%

Mitotane reduces human and mouse ACTH-secreting pituitary cell viability and function

Gentilin¹,

Tagliati²,

Terzolo³

et al. 2013

Journal of Endocrinology

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Medical therapy for Cushing's disease (CD) is currently based on agents mainly targeting adrenocortical function. Lately, pituitary-directed drugs have been developed, with limited efficacy. Mitotane, a potent adrenolytic drug, has been recently investigated for the treatment of CD, but the direct pituitary effects have not been clarified so far. The aim of our study was to investigate whether mitotane may affect corticotroph function and cell survival in the mouse pituitary cell line AtT20/D16v-F2 and in the primary cultures of human ACTHsecreting pituitary adenomas, as an in vitro model of pituitary corticotrophs. We found that in the AtT20/D16v-F2 cell line and in primary cultures, mitotane reduces cell viability by inducing caspase-mediated apoptosis and reduces ACTH secretion. In the AtT20/D16v-F2 cell line, mitotane reduces Pomc expression and blocks the stimulatory effects of corticotropinreleasing hormone on cell viability, ACTH secretion, and Pomc expression. These effects were apparent at mitotane doses greater than those usually necessary for reducing cortisol secretion in Cushing's syndrome, but still in the therapeutic window for adrenocortical carcinoma treatment. In conclusion, our results demonstrate that mitotane affects cell viability and function of human and mouse ACTH-secreting pituitary adenoma cells. These data indicate that mitotane could have direct pituitary effects on corticotroph cells.

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Virologic and Immunologic Evidence Supporting an Association between HHV-6 and Hashimoto's Thyroiditis

Cited by 129 publications

References 49 publications

Human Herpesvirus 6A Infection in CD46 Transgenic Mice: Viral Persistence in the Brain and Increased Production of Proinflammatory Chemokines via Toll-Like Receptor 9

Human Herpesvirus 6A Infection in CD46 Transgenic Mice: Viral Persistence in the Brain and Increased Production of Proinflammatory Chemokines via Toll-Like Receptor 9

Laboratory and Clinical Aspects of Human Herpesvirus 6 Infections

Mitotane reduces human and mouse ACTH-secreting pituitary cell viability and function

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