Interferon induced Autoimmune Thyroid Disease (AITD): a model for human autoimmunity

Multidimensional definition of the interferonopathy of Down syndrome and its response to JAK inhibition

Individuals with Down syndrome (DS) display chronic hyperactivation of interferon signaling. However, the clinical impacts of interferon hyperactivity in DS are ill-defined. Here, we describe a multiomics investigation of interferon signaling in hundreds of individuals with DS. Using interferon scores derived from the whole blood transcriptome, we defined the proteomic, immune, metabolic, and clinical features associated with interferon hyperactivity in DS. Interferon hyperactivity associates with a distinct proinflammatory phenotype and dysregulation of major growth signaling and morphogenic pathways. Individuals with the highest interferon activity display the strongest remodeling of the peripheral immune system, including increased cytotoxic T cells, B cell depletion, and monocyte activation. Interferon hyperactivity accompanies key metabolic changes, most prominently dysregulated tryptophan catabolism. High interferon signaling stratifies a subpopulation with elevated rates of congenital heart disease and autoimmunity. Last, a longitudinal case study demonstrated that JAK inhibition normalizes interferon signatures with therapeutic benefit in DS. Together, these results justify the testing of immune-modulatory therapies in DS.

JAKs and STATs from a Clinical Perspective: Loss-of-Function Mutations, Gain-of-Function Mutations, and Their Multidimensional Consequences

The JAK/STAT signaling pathway plays a key role in cytokine signaling and is involved in development, immunity, and tumorigenesis for nearly any cell. At first glance, the JAK/STAT signaling pathway appears to be straightforward. However, on closer examination, the factors influencing the JAK/STAT signaling activity, such as cytokine diversity, receptor profile, overlapping JAK and STAT specificity among non-redundant functions of the JAK/STAT complexes, positive regulators (e.g., cooperating transcription factors), and negative regulators (e.g., SOCS, PIAS, PTP), demonstrate the complexity of the pathway's architecture, which can be quickly disturbed by mutations. The JAK/STAT signaling pathway has been, and still is, subject of basic research and offers an enormous potential for the development of new methods of personalized medicine and thus the translation of basic molecular research into clinical practice beyond the use of JAK inhibitors. Gain-of-function and loss-of-function mutations in the three immunologically particularly relevant signal transducers STAT1, STAT3, and STAT6 as well as JAK1 and JAK3 present themselves through individual phenotypic clinical pictures. The established, traditional paradigm of loss-of-function mutations leading to immunodeficiency and gain-of-function mutation leading to autoimmunity breaks down and a more differentiated picture of disease patterns evolve. This review is intended to provide an overview of these specific syndromes from a clinical perspective and to summarize current findings on pathomechanism, symptoms, immunological features, and therapeutic options of STAT1, STAT3, STAT6, JAK1, and JAK3 loss-of-function and gain-of-function diseases.

Development of highly stable and de-immunized versions of recombinant alpha interferon: Promising candidates for the treatment of chronic and emerging viral diseases

Human interferon alpha (hIFN-α) administration constitutes the current FDA approved therapy for chronic Hepatitis B and C virus infections. Additionally, hIFN-α treatment efficacy was recently demonstrated in patients with COVID-19. Thus, hIFN-α constitutes a therapeutic alternative for those countries where vaccination is inaccessible and for people who did not respond effectively to vaccination. However, hIFN-α2b exhibits a short plasma half-life resulting in the occurrence of severe side effects. To optimize the cytokine's pharmacokinetic profile, we developed a hyperglycosylated IFN, referred to as GMOP-IFN.

Given the significant number of reports showing neutralizing antibodies (NAb) formation after hIFN-α administration, here we applied the DeFT (De-immunization of Functional Therapeutics) approach to develop functional, de-immunized versions of GMOP-IFN. Two GMOP-IFN variants exhibited significantly reduced ex vivo immunogenicity and null antiproliferative activity, while preserving antiviral function. The results obtained in this work indicate that the new de-immunized GMOP-IFN variants constitute promising candidates for antiviral therapy.

Induction of Vogt-Koyanagi-Harada Disease by Interferon-Alpha and Ribavirin Treatment in Patients with Hepatitis C: A Case Report and Review of the Literature

PURPOSE

To describe a case of Vogt-Koyanagi-Harada disease (VKH) presenting in a hepatitis C patient after interferon-alpha (IFN-α) and ribavirin treatment.

METHODS

A retrospective review of our patient and a review of the published literature.

RESULTS

A 59 year-old man developed VKH after the four months of IFN-α and ribavirin therapy for hepatitis C. The patient's VKH was controlled by systemic corticosteroids. The relationship between VKH and IFN-α is discussed based on the published literature.

CONCLUSIONS

VKH is a rare autoimmune complication triggered by interferon-alpha therapy; the T-cell modulatory properties of IFN-α possibly contribute to this association. Early diagnosis of VKH and aggressive systemic corticosteroid intervention are essential for this type of IFN-α -related autoimmune complication.

De-immunized and Functional Therapeutic (DeFT) versions of a long lasting recombinant alpha interferon for antiviral therapy

Interferon α (IFN-α) exerts potent antiviral, immunomodulatory, and antiproliferative activity and have proven clinical utility in chronic hepatitis B and C virus infections. However, repeated IFN-α administration induces neutralizing antibodies (NAb) against the therapeutic in a significant number of patients. Associations between IFN-α immunogenicity and loss of efficacy have been described. So as to improve the in vivo biological efficacy of IFN-α, a long lasting hyperglycosylated protein (4N-IFN) derived from IFN-α2b wild type (WT-IFN) was developed. However, in silico analysis performed using established in silico methods revealed that 4N-IFN had more T cell epitopes than WT-IFN. In order to develop a safer and more efficient IFN therapy, we applied the DeFT (De-immunization of Functional Therapeutics) approach to producing functional, de-immunized versions of 4N-IFN. Using the OptiMatrix in silico tool in ISPRI, the 4N-IFN sequence was modified to reduce HLA binding potential of specific T cell epitopes. Following verification of predictions by HLA binding assays, eight modifications were selected and integrated in three variants: 4N-IFN(VAR1), (VAR2) and (VAR3). Two of the three variants (VAR1 and VAR3) retained anti-viral function and demonstrated reduced T-cell immunogenicity in terms of T-cell proliferation and Th1 and Th2 cytokine levels, when compared to controls (commercial NG-IFN (non-glycosylated), PEG-IFN, WT-IFN and 4N-IFN). It was previously demonstrated that N-glycosylation improved IFN-α pharmacokinetic properties. Here, we further reduce immunogenicity as measured in vitro using T cell assays and cytokine profiling by modifying the T cell epitope content of a protein (de-immunizing). Taking into consideration the present results and previously reported immunogenicity data for commercial IFN-α2b variants, 4N-IFN(VAR1) and 4N-IFN-4N(VAR3) appear to be promising candidates for improved IFN-α therapy of HCV and HBV.

Hepatitis C virus infection and thyroid autoimmune disorders: A model of interactions between the host and the environment

The hepatitis C virus (HCV) infection is an important public health problem and it is associated with hepatic and extrahepatic manifestations. Autoimmune thyroid diseases are common in HCV infected patients and the standard interferon-based treatment is associated with an increase of the immune-mediated thyroid damage. Recent evidence in the literature analyzed critical points of the mechanisms of thyroid damage, focusing on the balance between the two sides of the interaction: The environment (virus infection with potential cross-reaction) and the host (susceptibility genes with consistent immune response). The spectrum of antiviral treatment for chronic HCV infection is rapidly expanding for the development of dual o triple therapy. The availability of interferon-free combined treatment with direct antiviral agents for HCV is very promising, in order to ameliorate the patient compliance and to reduce the development of thyroid autoimmunity.

Thyroid disorders and gastrointestinal and liver dysfunction: A state of the art review

Thyroid disorders commonly impact on the gastrointestinal system and may even present with gastrointestinal symptoms in isolation; for example, metastatic medullary thyroid carcinoma typically presents with diarrhoea. Delays in identifying and treating the underlying thyroid dysfunction may lead to unnecessary investigations and treatment, with ongoing morbidity, and can potentially be life-threatening. Similarly, gastrointestinal diseases can impact on thyroid function tests, and an awareness of the concept and management of non-thyroidal illness is necessary to avoid giving unnecessary thyroid therapies that could potentially exacerbate the underlying gastrointestinal disease. Dual thyroid and gastrointestinal pathologies are also common, with presentations occurring concurrently or sequentially, the latter after a variable time lag that can even extend over decades. Such an association aetiologically relates to the autoimmune background of many thyroid disorders (e.g. Graves' disease and Hashimoto's thyroiditis) and gastrointestinal disorders (e.g. coeliac disease and inflammatory bowel disease); such autoimmune conditions can sometimes occur in the context of autoimmune polyglandular syndrome. Emphasis should also be given to the gastrointestinal side effects of some of the medications used for thyroid disease (e.g. anti-thyroid drugs causing hepatotoxicity) and vice versa (e.g. interferon therapy causing autoimmune thyroid dysfunction). In this review, we discuss disorders of the thyroid-gut axis and identify the evidence base behind the management of such disorders.

Immunological loss-of-function due to genetic gain-of-function in humans: autosomal dominance of the third kind

All the human primary immunodeficiencies (PIDs) recognized as such in the 1950s were Mendelian traits and, whether autosomal or X-linked, displayed recessive inheritance. The first autosomal dominant (AD) PID, hereditary angioedema, was recognized in 1963. However, since the first identification of autosomal recessive (AR), X-linked recessive (XR) and AD PID-causing genes in 1985 (ADA; severe combined immunodeficiency), 1986 (CYBB, chronic granulomatous disease) and 1989 (SERPING1; hereditary angioedema), respectively, the number of genetically defined AD PIDs has increased more rapidly than that of any other type of PID. AD PIDs now account for 61 of the 260 known conditions (23%). All known AR PIDs are caused by alleles with some loss-of-function (LOF). A single XR PID is caused by gain-of-function (GOF) mutations (WASP-related neutropenia, 2001). In contrast, only 44 of 61 AD defects are caused by LOF alleles, which exert dominance by haploinsufficiency or negative dominance. Since 2003, up to 17 AD disorders of the third kind, due to GOF alleles, have been described. Remarkably, six of the 17 genes concerned also harbor monoallelic (STAT3), biallelic (C3, CFB, CARD11, PIK3R1) or both monoallelic and biallelic (STAT1) LOF alleles in patients with other clinical phenotypes. Most heterozygous GOF alleles result in auto-inflammation, auto-immunity, or both, with a wide range of immunological and clinical forms. Some also underlie infections and, fewer, allergies, by impairing or enhancing immunity to non-self. Malignancies are also rare. The enormous diversity of immunological and clinical phenotypes is thought provoking and mirrors the diversity and pleiotropy of the underlying genotypes. These experiments of nature provide a unique insight into the quantitative regulation of human immunity.

New and recurrent gain-of-function STAT1 mutations in patients with chronic mucocutaneous candidiasis from Eastern and Central Europe

BACKGROUND

Chronic mucocutaneous candidiasis disease (CMCD) may result from various inborn errors of interleukin (IL)-17-mediated immunity. Twelve of the 13 causal mutations described to date affect the coiled-coil domain (CCD) of STAT1. Several mutations, including R274W in particular, are recurrent, but the underlying mechanism is unclear.

OBJECTIVE

To investigate and describe nine patients with CMCD in Eastern and Central Europe, to assess the biochemical impact of STAT1 mutations, to determine cytokines in supernatants of Candida-exposed blood cells, to determine IL-17-producing T cell subsets and to determine STAT1 haplotypes in a family with the c.820C>T (R274W) mutation.

RESULTS

The novel c.537C>A (N179K) STAT1 mutation was gain-of-function (GOF) for γ-activated factor (GAF)-dependent cellular responses. In a Russian patient, the cause of CMCD was the newly identified c.854 A>G (Q285R) STAT1 mutation, which was also GOF for GAF-dependent responses. The c.1154C>T (T385M) mutation affecting the DNA-binding domain (DBD) resulted in a gain of STAT1 phosphorylation in a Ukrainian patient. Impaired Candida-induced IL-17A and IL-22 secretion by leucocytes and lower levels of intracellular IL-17 and IL-22 production by T cells were found in several patients. Haplotype studies indicated that the c.820C>T (R274W) mutation was recurrent due to a hotspot rather than a founder effect. Severe clinical phenotypes, including intracranial aneurysm, are presented.

CONCLUSIONS

The c.537C>A and c.854A>G mutations affecting the CCD and the c.1154C>T mutation affecting the DBD of STAT1 are GOF. The c.820C>T mutation of STAT1 in patients with CMCD is recurrent due to a hotspot. Patients carrying GOF mutations of STAT1 may develop multiple intracranial aneurysms by hitherto unknown mechanisms.

Genetic analysis of interferon induced thyroiditis (IIT): evidence for a key role for MHC and apoptosis related genes and pathways

Autoimmune thyroid diseases (AITD) have become increasingly recognized as a complication of interferon-alpha (IFNα) therapy in patients with chronic Hepatitis C virus (HCV) infection. Interferon-induced thyroiditis (IIT) can manifest as clinical thyroiditis in approximately 15% of HCV patients receiving IFNα and subclinical thyroiditis in up to 40% of patients, possibly resulting in either dose reduction or discontinuation of IFNα treatment. However, the exact mechanisms that lead to the development of IIT are unknown and may include IFNα-mediated immune-recruitment as well as direct toxic effects on thyroid follicular cells. We hypothesized that IIT develops in genetically predisposed individuals whose threshold for developing thyroiditis is lowered by IFNα. Therefore, our aim was to identify the susceptibility genes for IIT. We used a genomic convergence approach combining genetic association data with transcriptome analysis of genes upregulated by IFNα. Integrating results of genetic association, transcriptome data, pathway, and haplotype analyses enabled the identification of 3 putative loci, SP100/110/140 (2q37.1), HLA (6p21.3), and TAP1 (6p21.3) that may be involved in the pathogenesis of IIT. Immune-regulation and apoptosis emerged as the predominant mechanisms underlying the etiology of IIT.

Immune manipulation for Graves' disease: re-exploring an unfulfilled promise with modern translational research

Although Graves' disease is the commonest autoimmune thyroid disorder, current therapeutics typically center on the eradication of the antigenic stimulus (i.e. thyroid gland) rather than radically tackling the underlying autoimmune processes. Consequently, it is not a surprising fact that Graves' disease remains essentially a chronic drug-dependent ailment afflicting untold numbers worldwide for decades despite progress in deciphering its autoimmune nature. Addressing the latter is key to a future cure as underscored by appropriate, albeit crude, proof-of-concept scenarios of clinical remissions achieved with hematopoietic stem cell transplantation, immune down-regulation during pregnancy, use of corticosteroids or immunosuppressives, and cytokine biologics in animal models. Ongoing basic and translational research to further elucidate and refine our understanding of the pathogenesis of Graves' disease holds the promise of unraveling novel immune manipulative techniques that will bring the world a step closer to the elusive cure of the underlying autoimmunity amidst skepticisms on the value of the science from the present lack of paralleled advances at the bedside. We review the updated literature and describe the forms of immune manipulation hitherto explored that will offer a route to a future cure, from thionamides, hematopoietic stem cell transplantation to the latest immunomodulatory agents.

Thyroid dysfunction in Turkish patients with chronic hepatitis C receiving peginterferon plus ribavirin in the period of 2005-2010

Interferon-α based therapy for chronic hepatitis C (CHC) is associated with thyroiditis and thyroid dysfunction (TD). This study investigated whether TD during pegylated interferon-α (PEG-IFN) plus ribavirin treatment favors sustained viral response (SVR), and also the association between TD and PEG-IFN formulations. This retrospective study was performed in CHC patients who had received PEG-IFN plus ribavirin and had been followed for six months after treatment. Several factors were compared between patients with and without TD. 119 patients were included in the study. De novo incidence of TD was found to be 16.8%, and 16 of the 18 patients with TD achieved SVR. Although this rate was higher than patients without TD according to univariate analysis, logistic regression analysis revealed that there was not a significant association between TD and SVR, whereas baseline thyroperoxidase antibody (anti-TPO) positivity was the only significant predictor of TD. Moreover, TD was not associated with PEG-IFN type. Both interferon-α and hepatitis C virus (HCV) contribute to TD during antiviral therapy. It seems that there is no association between thyroid toxicity and viral clearance or type of PEG-IFN; however, anti-TPO positivity before treatment is the strongest predictor for TD during antiviral therapy.

TH17 deficiency in human disease

The differentiation of naive T cells into distinct subsets of effector T cells is critical for effective immunity against a wide variety of infectious agents in the environment. Activation of innate immune responses by Candida species through pattern-recognition receptors directs the subsequent development of naive T cells into T(H)17 cells, which are essential for effective mucosal immunity against fungi. Thorough analyses of cohorts of patients with unusual susceptibility to chronic mucocutaneous candidiasis resulting from T(H)17 deficiency have confirmed the role of T(H)17 cells and T(H)17 cytokines in human host defense against Candida species and have provided valuable insights into the complex process of T(H)17 cell development.

Gain-of-function human STAT1 mutations impair IL-17 immunity and underlie chronic mucocutaneous candidiasis

Chronic mucocutaneous candidiasis disease (CMCD) may be caused by autosomal dominant (AD) IL-17F deficiency or autosomal recessive (AR) IL-17RA deficiency. Here, using whole-exome sequencing, we identified heterozygous germline mutations in STAT1 in 47 patients from 20 kindreds with AD CMCD. Previously described heterozygous STAT1 mutant alleles are loss-of-function and cause AD predisposition to mycobacterial disease caused by impaired STAT1-dependent cellular responses to IFN-γ. Other loss-of-function STAT1 alleles cause AR predisposition to intracellular bacterial and viral diseases, caused by impaired STAT1-dependent responses to IFN-α/β, IFN-γ, IFN-λ, and IL-27. In contrast, the 12 AD CMCD-inducing STAT1 mutant alleles described here are gain-of-function and increase STAT1-dependent cellular responses to these cytokines, and to cytokines that predominantly activate STAT3, such as IL-6 and IL-21. All of these mutations affect the coiled-coil domain and impair the nuclear dephosphorylation of activated STAT1, accounting for their gain-of-function and dominance. Stronger cellular responses to the STAT1-dependent IL-17 inhibitors IFN-α/β, IFN-γ, and IL-27, and stronger STAT1 activation in response to the STAT3-dependent IL-17 inducers IL-6 and IL-21, hinder the development of T cells producing IL-17A, IL-17F, and IL-22. Gain-of-function STAT1 alleles therefore cause AD CMCD by impairing IL-17 immunity.

De novo autoimmune hepatitis subsequent to switching from type 2b to type 2a alpha-pegylated interferon treatment for recurrent hepatitis C after liver transplantation: report of a case

Interferon (IFN), which is the only possible agent for recurrent hepatitis C after liver transplantation, may cause serious immune-related disorders. We report a case of de novo autoimmune hepatitis (AIH), which developed subsequent to switching from 2b pegylated interferon-α (peg-IFN) to 2a peg-IFN after living donor liver transplantation (LDLT). A 51-year-old man with hepatitis C-associated liver cirrhosis underwent LDLT. About 13 months after the initiation of antiviral therapy, in the form of type 2b peg-IFN with ribavirin, a negative serum hepatitis C virus (HCV)-RNA titer was confirmed. Thereafter, the 2b peg-IFN was switched to 2a peg-IFN, 3 months after which severe liver dysfunction developed, despite a constantly negative HCV-RNA. Liver biopsy showed portal and periportal inflammatory infiltrates including numerous plasma cells, indicating AIH. He was treated with steroid pulse treatment, followed by high-level immunosuppression maintenance, but eventually died of Pneumocystis pneumonitis 4 months after the diagnosis of de novo AIH.

Environmental triggers of thyroiditis: hepatitis C and interferon-α

Autoimmune thyroid diseases (AITD) are postulated to develop as a result of a complex interplay between several genetic and environmental influences. The pathogenesis of AITD is still not clearly defined. However, among the implicated triggers (e.g. iodine, infections, medications), more recent data confirmed strong associations of AITD with the hepatitis C virus (HCV) infection and interferon-α (IFNα) therapy. Moreover, it is likely that HCV and IFN act in synergism to trigger AITD in patients. Indeed, approximately 40% of HCV patients develop either clinical or subclinical disease while receiving IFNα. Interferon induced thyroiditis (IIT) can manifest as non-autoimmune thyroiditis (presenting as destructive thyroiditis, or non-autoimmune hypothyroidism), or autoimmune thyroiditis [presenting with clinical features of Graves' disease (GD) or Hashimoto's thyroiditis (HT)]. Although not yet clearly understood, it is thought that IFNα can induce thyroiditis via both immune stimulatory and direct toxic effects on the thyroid. In view of the high frequency of IIT, routine screening and surveillance of HCV patients receiving IFNα is recommended to avoid the complications, such as cardiac arrhythmias, associated with thyrotoxicosis. In summary, IIT is a common clinical problem that can be readily diagnosed with routine thyroid function screening of HCV patients receiving IFN. The treatment of IIT consists of the standard therapy for differing clinical manifestations of IIT such as GD, HT, or destructive thyroiditis. However, anti-thyroid medications are not recommended in this setting since they can potentially be hepatotoxic.

Autoimmune thyroid diseases in children

The two major autoimmune thyroid diseases (ATDs) include Graves' disease (GD) and autoimmune thyroiditis (AT); both of which are characterized by infiltration of the thyroid by T and B cells reactive to thyroid antigens, by the production of thyroid autoantibodies and by abnormal thyroid function (hyperthyroidism in GD and hypothyroidism in AT). While the exact etiology of thyroid autoimmunity is not known, it is believed to develop when a combination of genetic susceptibility and environmental encounters leads to breakdown of tolerance. It is important to recognize thyroid dysfunction at an early stage by maintaining an appropriate index of suspicion.

Cases of interferon-alpha and interferon-beta-induced thyroiditis

Interferons are currently the major treatment modality for several malignant and non-malignant diseases such as chronic hepatitis C and B, multiple sclerosis, hematological malignancies, malignant melanoma, renal cell carcinoma, etc. Thyroid disorders develop in some of the interferon-treated patients with the incidence ranging from 1% to 35%. These complications may often result in dose reduction or discontinuation of interferon therapy. Interferon induced thyroid disorders can be classified as autoimmune and non-autoimmune thyroiditis. There are many studies on the development of thyroid dysfunction in interferon-alpha treated patients with chronic hepatitis C and in patients with multiple sclerosis treated with interferon-beta. There is a dearth of information about the incidence and characteristics of thyroid abnormalities in patients with hematological malignancies receiving interferon-alpha. A number of genetic determinants are discussed as causes for thyroid impairment (sex, age, ethnic group, genes involved in the thyroid immune regulation), as well as non-genetic factors (related to the underlying disease--hepatitis C virus; multiple sclerosis; therapeutic regimens of interferon administration, iodine concentration in the environment, presence of thyroid autoantibodies at the start of treatment, etc.). In this article we summarize the relevant data about the frequency and characteristics of thyroid disorders in patients treated with interferons, the risk factors and the mechanisms for their development and the peculiarities of the course, detection and treatment of these complications. The review of the literature motivates studying the thyroid function of specific groups of patients receiving interferon in order to clarify the influence of the factors drug and disease on the thyroid gland. Early detection and adequate treatment of thyroid dysfunction in these patients is important to avoid complications that may compromise treatment.

Hepatitis C and interferon induced thyroiditis

Autoimmune thyroid diseases (AITDs) are complex diseases that develop as a result of interactions between genetic, epigenetic, and environmental factors. Significant progress has been made in our understanding of the genetic and environmental triggers contributing to AITD. The major environmental triggers of AITD include iodine, smoking, medications, pregnancy, and possibly stress. In this review we will focus on two well-documented environmental triggers of AITD, hepatitis C virus (HCV) infection and interferon alpha (IFNa) therapy. Chronic HCV infection has been shown to be associated with increased incidence of clinical and subclinical autoimmune thyroiditis (i.e. the presence of thyroid antibodies in euthyroid subjects). Moreover, IFNa therapy of chronic HCV infection is associated with subclinical or clinical thyroiditis in up to 40% of cases which can be autoimmune, or non-autoimmune thyroiditis. In some cases interferon induced thyroiditis (IIT) in chronic HCV patients may result in severe symptomatology necessitating discontinuation of therapy. While the epidemiology and clinical presentation of HCV and interferon induced thyroiditis have been well characterized, the mechanisms causing these conditions are still poorly understood.

[Occurrence of diabetic ketoacidosis and autoimmune thyroiditis in a patient treated with pegylated interferon-alpha 2b and ribavirin for chronic hepatitis C]

Combined pegylated interferon and ribavirin therapy for chronic hepatitis C infection cause a wide range of side effects, including flu-like syndrome, hematological abnormalities, cardiovascular symptoms, gastrointestinal symptoms, pulmonary dysfunction, depression, and retinopathy. Interferon-alpha has been shown to be related to the development of various autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, autoimmune thyroid disease, and type 1 diabetes mellitus (DM). Type 1 DM and thyroid disease respectively develop in 0.08-2.61% and 10-15% of patients treated with combined interferon-alpha and ribavirin for chronic hepatitis C. The coexistence of type 1 DM and autoimmune thyroiditis was rarely reported. We report a case of a 33-year-old female patient with chronic hepatitis C who simultaneously developed diabetic ketoacidosis and autoimmune thyroiditis after treatment with pegylated interferon-alpha 2b and ribavirin.

Interferon induced thyroiditis

Interferon-alpha (IFNalpha) is used for the treatment of various disorders, most notable chronic hepatitis C virus (HCV) infection. One of the commonest side effects of IFNalpha therapy is thyroiditis, with up to 40% of HCV patients on IFNalpha developing clinical or subclinical disease. In some cases interferon induced thyroiditis (IIT) may result in severe symptomatology necessitating discontinuation of therapy. IIT can manifest as clinical autoimmune thyroiditis, presenting with symptoms of classical Hashimoto's thyroiditis or Graves' disease, or as non-autoimmune thyroiditis. Non-autoimmune thyroiditis can manifest as destructive thyroiditis, with early thyrotoxicosis and later hypothyroidism, or as non-autoimmune hypothyroidism. While the epidemiology and clinical presentation of IIT have been well characterized the mechanisms causing IIT are still poorly understood. It is likely that the hepatitis C virus (HCV) itself plays a role in the disease, as the association between HCV infection and thyroiditis is well established. It is believed that IFNalpha induces thyroiditis by both immune stimulatory effects and by direct effects on the thyroid. Early detection and therapy of this condition are important in order to avoid complications of thyroid disease such as cardiac arrhythmias.

Autoimmune thyroiditis as an indicator of autoimmune sequelae during cancer immunotherapy

Improving cancer immunotherapy by targeting T cell network also triggers autoimmunity. We disrupted regulatory T cell (Treg) function to probe the balance between breast cancer vaccination and autoimmune thyroiditis (EAT) in four models, with particular attention to MHC-associated susceptibility, EAT induction with mouse thyroglobulin (mTg) without adjuvant, and tolerance to Her-2/neu in transgenic mice. 1) In EAT-resistant BALB/c mice, Treg depletion enhanced tumor regression, and facilitated mild thyroiditis induction. 2) In Her-2 tolerant C57BL/6 mice expressing HLA-DR3, an EAT-susceptibility allele, Her-2 DNA vaccinations must follow Treg depletion for (Her-2xDR3)F(1) mice to resist tumor challenge; thyroiditis incidence was moderated by the EAT-resistant IA(b) allele. 3) In neu tolerant, EAT-resistant BALB/c mice, implanted neu(+) tumor also regressed only after Treg depletion and DNA vaccinations. Tumor immunity was long-term, providing protection from spontaneous tumorigenesis. In all three, immune stimuli from concurrent tumor regression and EAT development have a noticeable, mutually augmenting effect. 4) In Treg-depleted, EAT-susceptible CBA/J mice, strong tumor protection was established by immunization with a cell vaccine. mTg injections led to greater thyroiditis incidence and severity. Combination models with MHC class II diversity should facilitate autoimmunity risk assessment and management while generating tumor immunity.

Type I IFNs and their role in the development of autoimmune diseases

BACKGROUND

Since their initial use in the 1980s, IFNs have become an essential component of the therapy for many diseases such as hepatitis and multiple sclerosis. Although they have been extremely useful in conditions that pose therapeutic challenges, complications associated with their use have been widely reported including emerging reports of several autoimmune diseases. Many of these reports have shed light on the pathogenesis of autoimmune disorders and helped to highlight not only the critical role of type I IFNs in defense against viral infections but also the pivotal role they occupy in the interface between innate and adaptive immunity. Many patients with autoimmune disease have increased responsiveness to type I IFNs (alpha/beta), and therapy with these cytokines has induced or unmasked autoimmune disease in many additional patients.

OBJECTIVE

The objective of this paper is to discuss the role of type I IFNs in autoimmunity.

METHODS

The literature regarding type I IFNs and autoimmunity was reviewed using the Medline database from 1950 to 2009. Search terms included 'interferon alpha' and 'autoimmune disease' and 'interferon beta' and 'autoimmune disease'. Case reports, case series, reviews and prospective studies were included in the analysis.

RESULTS/CONCLUSIONS

In the literature a variety of autoimmune disorders have reportedly been induced by the use of type I IFNs, being used, although these are primarily in the form of case reports and case series. Nevertheless, there is a growing body of molecular evidence to support the clinical association. The role of IFNs in the induction of autoimmunity is complex with interplay of many genetic and environmental factors that influence the balance between normal and aberrant immune responsiveness, ultimately leading to the observed clinical manifestations.

The etiology of autoimmune thyroid disease: a story of genes and environment

Autoimmune thyroid diseases (AITDs), including Graves' disease (GD) and Hashimoto's thyroiditis (HT) are prevalent autoimmune diseases, affecting up to 5% of the general population. Autoimmune thyroid diseases arise due to complex interactions between environmental and genetic factors. Significant progress has been made in our understanding of the genetic and environmental triggers contributing to AITD. However, the interactions between genes and environment are yet to be defined. Among the major AITD susceptibility genes that have been identified and characterized is the HLA-DR gene locus, as well as non-MHC genes including the CTLA-4, CD40, PTPN22, thyroglobulin, and TSH receptor genes. The major environmental triggers of AITD include iodine, medications, infection, smoking, and possibly stress. Recent data on the genetic predisposition to AITD lead to novel putative mechanisms by which the genetic-environmental interactions may lead to the development of thyroid autoimmunity.

HCV E2 protein binds directly to thyroid cells and induces IL-8 production: a new mechanism for HCV induced thyroid autoimmunity

HCV infection is well-known to be associated with autoimmune thyroiditis. However, the mechanisms by which HCV triggers thyroiditis are unknown. We hypothesized that HCV envelope proteins could induce thyroidal inflammation directly, thereby triggering thyroiditis by a bystander activation mechanism. To test this hypothesis we examined whether the HCV receptor CD81 was expressed and functional on thyroid cells. We found significant levels of CD81 mRNA by QPCR analysis, as well as CD81 protein by flow cytometric (FACS) analysis. Incubation of thyroid cells with HCV envelope glycoprotein E2 resulted in E2 binding to thyroid cells and activation of IL-8, an important pro-inflammatory cytokine. Intriguingly, thyroid cells incubated with E2 continued to proliferate normally and did not undergo apoptosis, as was reported in hepatocytes. We conclude that: (1) HCV envelope glycoprotein E2 can bind to CD81 receptors which are expressed on thyroid cells and induce a cascade of signaling pathway leading to IL-8 release; and (2) HCV may trigger thyroiditis in genetically susceptible individuals by bystander activation mechanisms.

Interferon alpha treatment and thyroid dysfunction

Interferon alpha (IFN alpha) is the cornerstone therapeutic agent for chronic hepatitis C virus (HCV) infection. Prospective studies have shown that up to 15% of HCV patients receiving IFN alpha develop clinical thyroid disease, and up to 40% become thyroid antibody positive. In some cases IFN-induced thyroiditis (IIT) may result in discontinuation of interferon therapy; thus, IIT represents a major clinical problem for hepatitis C patients receiving IFN alpha therapy. Recently, the mechanisms leading to the development of IIT have begun to be unraveled. It is now clear that HCV itself plays a role in the disease. Moreover, recent data suggest the IFN alpha precipitates thyroiditis by both immune modulatory mechanisms and direct thyroid toxic effects. Genetic factors also play a major role in the etiology of IIT. IIT can manifest both as clinical autoimmune thyroiditis (ie, Hashimoto's thyroiditis and Graves' disease) and as nonautoimmune thyroiditis (ie, destructive thyroiditis). Early detection and therapy of these conditions are important to avoid complications of thyroid disease such as cardiac arrhythmias. This article reviews the epidemiology and clinical manifestations of IIT and the mechanisms causing IIT, focusing on the role of HCV.

The incidence and evolution of thyroid dysfunction during interferon-alpha therapy in children with chronic hepatitis B infection

AIM

To assess the effect of interferon-alpha (IFN-alpha) therapy on thyroid functions in children with chronic hepatitis B infection (CHB).

METHODS

Sixty-eight children (7.8 +/- 3.6 years) were treated with 5 (n = 37, group I) or 10 MU/m2 (n = 31, group II) IFN for 6 months. Thyroid hormones, thyrotropin, thyrotropin-releasing hormone stimulation test, thyroid peroxidase and thyroglobulin autoantibodies were evaluated.

RESULTS

Baseline features were not different in the two groups. After therapy, thyroid dysfunction was 27% and 41.9% in groups I and II (n.s.). Subclinical hypothyroidism was 17.9%/ 29%, subclinical hyperthyroidism 5.4%/12.9%, hypothyroidism 2.7%/-, and thyroid antibody positivity 2.7%/- in groups I and II (n.s.). Thyroid dysfunction was 33.8% in the whole group (p = 0.001). Predictors of IFN induced-thyroid dysfunction were female sex and age < 6 years. Thyroid dysfunction resolved within median 6 months in all but three children.

CONCLUSION

Although IFN-induced thyroid dysfunction is mostly subclinical and reversible, this side effect should be kept in mind.

Pegylated interferon-induced immune-mediated hepatitis post-liver transplantation

A 55-year-old Caucasian male developed a well characterized autoimmune hepatitis after completing treatment with pegylated interferon and ribavirin for recurrent hepatitis C. We hypothesize that pegylated interferon triggered a severe form of immune-mediated hepatitis.

The clinical and physiological spectrum of interferon-alpha induced thyroiditis: toward a new classification

Interferon-alpha (IFNalpha) is a major treatment modality for several malignant and nonmalignant diseases, especially hepatitis C. Prospective studies have shown that up to 15% of patients with hepatitis C receiving IFNalpha develop clinical thyroid disease, and up to 40% were reported to develop thyroid antibodies. Some of these complications may result in discontinuation of interferon therapy. Thus, interferon induced thyroiditis (IIT) is a major clinical problem for patients receiving interferon therapy. IIT can be classified as autoimmune type and non-autoimmune type. Autoimmune IIT may manifest by the development of thyroid antibodies without clinical disease, or by clinical disease which includes both autoimmune hypothyroidism (Hashimoto's thyroiditis) and autoimmune thyrotoxicosis (Graves' disease). Non-autoimmune IIT can manifest as destructive thyroiditis or as hypothyroidism with negative thyroid antibodies. Early detection and therapy of these conditions is important in order to avoid complications of thyroid disease such as cardiac arrhythmias. While it is not clear which factors contribute to the susceptibility to IIT, recent evidence suggests that genetic factors, gender, and hepatitis C virus infection may play a role. In contrast, viral genotype and therapeutic regimen do not influence susceptibility to IIT. The etiology of IIT is unknown and may be secondary to immune modulation by IFNalpha and/or direct effects of interferon on the thyroid. In this review we discuss the clinical and pathophysiological aspects of IIT, and we are proposing a new, etiology-based classification of IIT, as well as an algorithm for diagnosis and treatment of IIT.

Interferon-alpha-induced hyperthyroidism: a three-stage evolution from silent thyroiditis towards Graves' disease

Autoimmune thyroid disease is a common side-effect of interferon-alpha (IFN-alpha) treatment of viral hepatitis C. We have described three patients with hepatitis C for whom IFN-alpha and ribavirin were prescribed and who developed two successive phases of silent thyroiditis followed by hyperthryroidism relapse due to Graves' disease. These three men had no known history of familial or personal thyroid disease. Destructive thyrotoxicosis appeared 4-6 months after starting IFN-alpha, followed by Graves' hyperthyroidism within 8 to 11 months. The thyrotropin (TSH) level was normal before IFN-alpha was started. The diagnosis of destructive thyroiditis was confirmed by anti-TSH receptor antibody (TSHRAb) negativity and the absence of radionuclide ((123)I or (99)Tc) uptake on thyroid scintiscans. Eight to eleven months after starting treatment, TSHRAb positivity and intense scintigraphic uptake confirmed the appearance of Graves' disease. IFN-alpha was continued in only one patient. Hence, hyperthyroidism induced by IFN-alpha could correspond to the first phase of silent thyroiditis, to Graves' disease or to the succession of both. Rigorous diagnostic procedures with repeated scintiscans and TSHRAb titering are necessary to avoid a false diagnosis and inappropriate therapy.

Adrenal cortex autoantibodies in subjects with normal adrenal function

The recent advances in our understanding of immunology have greatly improved our knowledge about the natural history of autoimmune diseases and, in particular, of autoimmune Addison's disease (Autoimmune AD). Autoimmune AD is a chronic disorder with a long preclinical period marked by the presence of adrenal cortex autoantibodies (ACAs). In this chapter the main data on this will be analyzed. The populations with the highest risk of Autoimmune AD are first relatives of patients with AAD and patients with autoimmune diseases, particularly those with chronic hypoparathyroidism or with premature ovarian failure. The best markers to identify the subjects at risk are ACAs detected by the immunofluorescence test on human or animal tissues, or 21-hydroxylase autoantibodies (21-OHAbs) detected by radioimmunoassay (RIA). The evaluation of adrenal cortex function in these individuals includes the basal determination of adrenocorticotropic hormone (ACTH), cortisol, aldosterone, plasma renin activity and cortisol after intravenous stimulation with synthetic ACTH. The multivariate analysis of the main factors (genetics, age, gender, titers of antibodies, pre-existing disease, status of the adrenal function) revealed that the risk of future AAD depends only on the presence of high antibody titers, chronic hypoparathyroidism or chronic candidiasis and adrenal dysfunction. On the basis of these parameters the risk of future Autoimmune AD can be calculated with an equation model. Patients with different risk scores need to be monitored at different time intervals, and those at high risk need to be strictly monitored and are the ideal subjects for future prevention trials.