Autoimmune Thyroid Diseases: Immuogenetic loci and use of new methods for detection of virus in thyroid tissue with impact on novel therapy methods.

In cooperation with Professor Tomer at Mount Sinai Hospital NY-USA, we have conducted cell studies to look for the cellular response to virus protein and virus infection in human thyroid cells. Studies have shown that different viral proteins may individually induce host responses to infection. Hepatitis C virus (HCV) infection was used as a model as thyroiditis is one of the most common extra hepatic manifestations of HCV. We demonstrated that thyroid cells express HCV receptors. Stimulation of human thyroid cells in culture with HCV envelop protein activates a cascade of inflammatory responses. HCV envelope protein induced production of several major cytokines and chemokines involved in autoimmunity. Furthermore, HCV envelop protein induced production of several heat shock proteins. We complemented our study with direct HCV infection of humane thyrocytes and to compare the molecular mechanisms of HCV infection in thyroid with hepatic cells. While HCV infection induces activation of mainly apoptotic pathways, infection of thyrocytes induces activation of by far more genes and cellular pathways. Our data support a key role for viral infection in triggering thyroid autoimmunity by bystander mechanisms. We have further developed a protocol for an intervention study (RTC). We want to test if antiviral treatment may reverse the development of thyroiditis in preclinical conditions, and or shorten then duration of the disease at the onset of disease. We will continue our investigation on viruses and molecular pathways in search for development of new therapy strategies.

Hovedformål med denne studien er å undersøke hvordan virus infeksjon kan bidra til utvikling av thyreoidea autoimmunitet. Årsak til autoimmune thyreoidea sykdommer er ikke helt kartlagt men det er økende evidens at virus infeksjon kan være utløsende faktor i genetisk disponerte personer. Vår tidligere studie viste at virus eller virus markører som interferon, var hyppigere til stede i vevsprøven tatt fra thyreoidea hos pasienter med autoimmune thyreoidea sykdommer (Graves’ hyperthyreose og Hashimoto thyreoiditt) enn i friske personer. I denne studien og i samarbeid med professor Yaron Tomer ved Mount Sina Hospital i NY og Professor Jason Blackard ved Univesity of Cincinnati, har vi undersøkt humane thyreoidea celler og om disse kan bli infisert med virus, og hvilke immunologisk respons som oppstår etter infeksjonen. I dette prosjektet har vi brukt hepatitt C virus (HCV) som en modell for virus infeksjon. Grunnen er at hepatitt C infeksjon ofte har vært assosiert med autoimmune tilstander. Autoimmune thyreoidea sykdommer har vært en av de hyppigste former for ekstrahepatiske manifestasjoner ved Hepatitt C. Hepatitt C virus er et RNA virus som koder for 10 forskjellige proteiner. Studier har vist at de forskjellige virus proteiner alene kan indusere immunologiske reaksjoner. I den første delen av studien har vi påvist at thyreoideaceller på lik linje med hepatocytter uttrykker den hoved reseptor for HCV, CD-81. Stimulering med HCV E2 protein (envelope protein 2) induserer overekspresjon av de fleste HCV reseptorene i thyreoideaceller inkludert CD81. Videre E2 protein induserer en sterk økning i viktige cytokiner og potente kjemokiner i normale humane thyreoidea celler . Disse markørene er kjent for å være involvert i utvikling av autoimmunitet. RNA sekvensering med de nyeste metodene med transkriptom analyse viser oppregulering av flere tusen gener. Mange av disse genene er dokumentert medvirkende i utvikling av autoimmunitet. Ved hjelp av Ingenuity Pathway program identifiserer man mange oppregulert mange pathways. Av særlig interesse er at det ble konstatert en overekspresjon av flere «heat shock proteiner» (HSP). HSP har vist å være involvert i utvikling av autoimmune thyreoidea sykdommer. I den andre delen av studien har vi vurdert effekten av HCV infeksjon på thyreoidea celler sammenlignet med hepatocytter. HCV induserer apoptose i hepatocytter mens thyreoideaceller lettere overlever infeksjonen. Derimot setter infeksjon i thyreoideaceller i gang en rekke immunologiske responser. Resultatene fra RNA sekvensering er under arbeid.

Autoimmune thyroid diseases (AITD) are prevalent and complex diseases affecting up to 6% of the population. AITD mainly include Graves' disease (autoimmune hyperthyroidism), and Hashimoto thyroiditis (autoimmune hypothyroidism). Studies have shown that GD and HT share some common. AITDs are multifactorial diseases and despite decades of basic research the cause of the disease is still unclear. However, it is of general acceptance that the disease is caused by interplay between genetic factors and environmental triggers. Epidemiological studies, twin studies and family studies and other genetic studies support the importance of environmental factors. In this study we focus on both genetic factors and an important environmental factor, viral infection. In this international project, we are working with highly qualified group with many years of research within genetics, immunology and virology. We have been a part of a study looking for the susceptibility genes in patients with young-age of onset Graves' disease. HLA haplotype has so far shown the strongest association with AITD in all previous studies. The results of our study revealed new susceptibility genes such as BTNL2, NOTCH4, TNFAIP3, and CXCR4, in addition to the well known HLA class II loci. Not surprising, pathway analysis shows the importance of the involvement of immunological cells T helper cells, B cells and antigen presenting cells. The results of this study are published in highly ranked journal JCEM. Lately, it has become clear that the biology and the mechanisms behind diseases are important factors for development of new therapeutic regiments. In collaboration with Dr. Tomer's research lab at Mount Sinai Hospital in NY (Postdoc candidate Sara Hammerstad), we are currently working on the effect of viral infection on thyroid tissue. It is known that 40% of patients with hepatitis C infection present thyroid antibodies, also up to 40% of these patients develop thyroid diseases after treatment with IFNa. In the current study we are studying the mechanisms that viral infection induces autoimmunity. Specifically, we are looking for the effect of hepatitis C virus infection in thyroid cell lines in terms of expression and secretion of cytokines, involved immunological pathways, and epigenetic changes. The results of this study will be presented and published during 2015. Furthermore, we aim to start an intervention study to evaluate the effect of anti viral treatment. We are currently working on development of protocols. If viruses are important for the development of autoimmune thyroid disease, new therapeutic regiments might be developed.