Hepatitis C Virus E2 Protein Induces Upregulation of IL-8 Pathways and Production of Heat Shock Proteins in Human Thyroid Cells

Damage-associated molecular patterns in viral infection: potential therapeutic targets

Frequent viral infections leading to infectious disease outbreaks have become a significant global health concern. Fully elucidating the molecular mechanisms of the immune response against viral infections is crucial for epidemic prevention and control. The innate immune response, the host's primary defense against viral infection, plays a pivotal role and has become a breakthrough in research mechanisms. A component of the innate immune system, damage-associated molecular patterns (DAMPs) are involved in inducing inflammatory responses to viral infections. Numerous DAMPs are released from virally infected cells, activating downstream signaling pathways via internal and external receptors on immune cells. This activation triggers immune responses and helps regulate viral host invasion. This review examines the immune regulatory mechanisms of various DAMPs, such as the S100 protein family, high mobility group box 1 (HMGB1), and heat shock proteins, in various viral infections to provide a theoretical basis for designing novel antiviral drugs.

Protective and stochastic correlation between infectious diseases and autoimmune disorders

A priori, early exposure to a wide range of bacteria, viruses, and parasites appears to fortify and regulate the immune system, potentially reducing the risk of autoimmune diseases. However, improving hygiene conditions in numerous societies has led to a reduction in these microbial exposures, which, according to certain theories, could contribute to an increase in autoimmune diseases. Indeed, molecular mimicry is a key factor triggering immune system reactions; while it seeks pathogens, it can bind to self-molecules, leading to autoimmune diseases associated with microbial infections. On the other hand, a hygiene-based approach aimed at reducing the load of infectious agents through better personal hygiene can be beneficial for such pathologies. This review sheds light on how the evolution of the innate immune system, following the evolution of molecular patterns associated with microbes, contributes to our protection but may also trigger autoimmune diseases linked to microbes. Furthermore, it addresses how hygiene conditions shield us against autoimmune diseases related to microbes but may lead to autoimmune pathologies not associated with microbes.

Autoimmune Thyroid Diseases

Autoimmune thyroid diseases (AITDs) include a wide spectrum of thyroid diseases affecting more commonly women than men. The most frequent forms are Graves' Disease (GD) and Hashimoto's thyroiditis / Autoimmune Thyroiditis (AIT), but there are also other immunogenic destructive forms of thyroiditis, that is, silent and postpartum thyroiditis. In the last decade, AITDs and other inflammatory thyroid diseases related to anti-tumor molecular drugs are more frequently seen due to the widespread use of tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors (ICPIs). Autoimmune thyroiditis related to SARS-CoV-2 infection has been a novel entity in recent years. Graves' Disease and AIT may shift from hyperthyroidism to hypothyroidism, which may complicate the differential diagnosis and further treatment strategy. Moreover, all AITDs may manifest with thyrotoxicosis (a clinical condition marked with high serum levels of thyroid hormones) which has to be distinguished from hyperthyroidism (increased thyroid hormone production and secretion as a result of hyperfunctioning thyroid gland) due to different therapeutic approaches. Nuclear medicine techniques, such as radioiodine uptake (RAIU) and thyroid scintigraphy, using 99mTc- pertechnetate (Na[99mTc]TcO4) or 123-Iodine (Na[123I]I), have a crucial role in the differential diagnosis. Measurement of thyroid antibodies, e.g. thyroid peroxidase antibodies (TPO) and thyrotropin receptor antibodies (TRAb), as well as thyroid ultrasound, are complementary methods in the evaluation of thyroid disorders.

Genetic Factors for Coronary Heart Disease and Their Mechanisms: A Meta-Analysis and Comprehensive Review of Common Variants from Genome-Wide Association Studies

Genome-wide association studies (GWAS) have discovered 163 loci related to coronary heart disease (CHD). Most GWAS have emphasized pathways related to single-nucleotide polymorphisms (SNPs) that reached genome-wide significance in their reports, while identification of CHD pathways based on the combination of all published GWAS involving various ethnicities has yet to be performed. We conducted a systematic search for articles with comprehensive GWAS data in the GWAS Catalog and PubMed, followed by a meta-analysis of the top recurring SNPs from ≥2 different articles using random or fixed-effect models according to Cochran Q and I2 statistics, and pathway enrichment analysis. Meta-analyses showed significance for 265 of 309 recurring SNPs. Enrichment analysis returned 107 significant pathways, including lipoprotein and lipid metabolisms (rs7412, rs6511720, rs11591147, rs1412444, rs11172113, rs11057830, rs4299376), atherogenesis (rs7500448, rs6504218, rs3918226, rs7623687), shared cardiovascular pathways (rs72689147, rs1800449, rs7568458), diabetes-related pathways (rs200787930, rs12146487, rs6129767), hepatitis C virus infection/hepatocellular carcinoma (rs73045269/rs8108632, rs56062135, rs188378669, rs4845625, rs11838776), and miR-29b-3p pathways (rs116843064, rs11617955, rs146092501, rs11838776, rs73045269/rs8108632). In this meta-analysis, the identification of various genetic factors and their associated pathways associated with CHD denotes the complexity of the disease. This provides an opportunity for the future development of novel CHD genetic risk scores relevant to personalized and precision medicine.

The role of activated monocyte IFN/SIGLEC1 signalling in Graves' disease

Graves' disease (GD) is characterized by dysregulation of the immune system with aberrant immune cell function. However, there have been few previous studies on the role of monocytes in the pathology of GD. The object of this study was to investigate whether and how monocytes participate in GD pathology. CD14+ monocytes were isolated from untreated initial GD patients and healthy controls. Then, RNA-seq was performed to investigate changes in global mRNA expression in monocytes and found that type I interferon (IFN) signalling was among the top upregulated signalling pathways in GD monocytes. Type I IFN-induced sialic acid-binding immunoglobulin-like lectin1 (SIGLEC1) expression was significantly upregulated in untreated GD patients and correlated with thyroid parameters. Patient serum SIGLEC1 concentrations were reduced after anti-thyroid drug treatment. Inhibiting SIGLEC1 expression could inhibit proinflammatory cytokine (IL-1β, IL-6, IL-8, IL-10 and M-CSF) expression in monocytes. In conclusion, our study suggested that type I IFN-mediated monocyte activation could have a deleterious effect on the pathogenesis of GD. These observations indicated that the inhibition of type I IFN-activated monocytes/macrophages could have a therapeutic effect on GD remission.

High Prevalence of Common Human Viruses in Thyroid Tissue

INTRODUCTION

Evidence points to viral infections as possible triggers of autoimmune thyroid disease (AITD), but little is known about the prevalence of common viruses in the thyroid gland. Using a novel approach based on virus enrichment in multiple cell lines followed by detection of the viral genome and visualization of viral proteins, we investigated the presence of multiple human viruses in thyroid tissue from AITD patients and controls.

METHODS

Thyroid tissue was collected by core needle biopsy or during thyroid surgery from 35 patients with AITD (20 Graves' disease and 15 Hashimoto's thyroiditis). Eighteen thyroid tissue specimens from patients undergoing neck surgery for reasons other than thyroid autoimmunity served as controls. Specimens were tested for the presence of ten different viruses. Enteroviruses and human herpesvirus 6 were enriched in cell culture before detection by PCR and immunofluorescence, while the remaining viruses were detected by PCR of biopsied tissue.

RESULTS

Forty of 53 cases (75%) carried an infectious virus. Notably, 43% of all cases had a single virus, whereas 32% were coinfected by two or more virus types. An enterovirus was found in 27/53 cases (51%), human herpesvirus 6 in 16/53 cases (30%) and parvovirus B19 in 12/53 cases (22%). Epstein-Barr virus and cytomegalovirus were found in a few cases only. Of five gastroenteric virus groups examined, only one was detected in a single specimen. Virus distribution was not statistically different between AITD cases and controls.

CONCLUSION

Common human viruses are highly prevalent in the thyroid gland. This is the first study in which multiple viral agents have been explored in thyroid. It remains to be established whether the detected viruses represent causal agents, possible cofactors or simple bystanders.

Autoimmune Thyroid Disease and Psoriasis Vulgaris after COVID-19 in a Male Teenager

COVID-19 is implicated in triggering autoimmune, dermatologic, and thyroid diseases. We present a first known case of development of Graves' disease and psoriasis vulgaris in a previously healthy male teenager without any family history, diagnosed after COVID-19 infection. Evaluation of “long COVID syndrome” should include thorough history and thyroid evaluation.

Immune Transcriptome of Cells Infected with Enterovirus Strains Obtained from Cases of Autoimmune Thyroid Disease

Background: Hashimoto’s thyroiditis and Graves’ disease are autoimmune thyroid disorders (AITD) of unknown origin. Enterovirus (EV) infection of thyroid cells has been implicated as a possible initiator of cell damage and of organ-specific autoimmunity. We asked whether persistent infection of human epithelial cells with EV strains obtained from thyroid tissue of AITD patients could be associated with transcriptional changes capable of fostering immunopathology. Methods: EV isolates obtained from thyroid tissue of AITD cases were used to infect the AV3 epithelial cell line. AV3 cells incubated with a virus-free medium from thyroid tissue of subjects without evidence of thyroid autoimmunity were used as uninfected controls. Transcripts of immune-related genes were compared in infected vs. uninfected cells. Results: The EV genome and antigens were detected only in the cells exposed to AITD-derived virus isolates, not in control cells. Persistent EV infection, while suppressing transcription of several type I IFN and cytokine determinants, was associated with enhanced transcription of NFKB1/RELA, IFNAR1, JAK1/STAT1, i.e., the determinants that play key immunologic roles. Infection also led to upregulation of the CCL2 chemokine and the IL-18 pro-inflammatory interleukin. Conclusion: As in the case of EV strains obtained from autoimmune diabetes, results show that the EV strains that are present in the thyroid of AITD cases do repress IFN and cytokine pathways. JAK1/STAT1 upregulation supports activation of TLR pathways and aberrant T cell signaling. In the early phases of AITD, our results highlight the potential benefit of interventions aimed at blocking the viral infection and easing the inflammatory response.

HLA Class I Upregulation and Antiviral Immune Responses in Graves Disease

CONTEXT

The origin of Graves disease (GD) remains elusive. However, evidence of an association between GD and viral infections is emerging. Human leukocyte antigen (HLA) class I presents viral antigens to circulating immune cells and plays a crucial role in the defense against viral infections.

OBJECTIVE

This work aimed to investigate HLA class I expression, enterovirus presence, and the viral immune response proteins signal transducer and activation of transcription 1 (STAT1) and protein kinase R (PKR) in thyroid tissue from GD patients.

METHODS

We collected thyroid tissue from core needle biopsies or surgical specimens from 48 GD patients and 24 controls. Standard immunohistochemistry was used to detect HLA class I and enteroviral capsid protein 1 (VP1) on formalin-fixed and paraffin-embedded tissue. STAT1 and PKR were examined by combined immunofluorescence staining. HLA class I expression score was the main outcome measure.

RESULTS

The HLA class I expression score, which takes both proportion and intensity of immunostaining into account, was significantly higher in GD patients (3.1 ± 3.3) than in controls (0.5 ± 0.9) (P < .001). Significantly more VP1 positive thyroid cells were found GD samples (50.1 ± 30.5%) than in controls (14.9 ± 10.5%) (P < .001). STAT1 and HLA class I were found within the same thyroid cells and PKR and VP1 were also colocalized within thyroid cells.

CONCLUSION

HLA class I is upregulated in GD and enterovirus protein is prevalent in thyroid tissue. The colocalization of HLA class I with STAT1 and VP1 with PKR indicates an antiviral tissue response. These findings support the concept of a link between viral infections and GD.

Evidence for B cell maturation but not trained immunity in uninfected infants exposed to hepatitis C virus

OBJECTIVES

Vertical transmission of hepatitis C virus (HCV) is rare compared with other chronic viral infections, despite that newborns have an immature, and possibly more susceptible, immune system. It further remains unclear to what extent prenatal and perinatal exposure to HCV affects immune system development in neonates.

DESIGN

To address this, we studied B cells, innate immune cells and soluble factors in a cohort of 62 children that were either unexposed, exposed uninfected or infected with HCV. Forty of these infants were followed longitudinally from birth up until 18 months of age.

RESULTS

As expected, evidence for B cell maturation was observed with increased age in children, whereas few age-related changes were noticed among innate immune cells. HCV-infected children had a high frequency of HCV-specific IgG-secreting B cells. Such a response was also detected in some exposed but uninfected children but not in uninfected controls. Consistent with this, both HCV-exposed uninfected and HCV-infected infants had evidence of early B cell immune maturation with an increased proportion of IgA-positive plasma cells and upregulated CD40 expression. In contrast, actual HCV viraemia, but not mere exposure, led to alterations within myeloid immune cell populations, natural killer (NK) cells and a distinct soluble factor profile with increased levels of inflammatory cytokines and chemokines.

CONCLUSION

Our data reveal that exposure to, and infection with, HCV causes disparate effects on adaptive B cells and innate immune cell such as myeloid cells and NK cells in infants.

Aquareovirus NS31 protein serves as a specific inducer for host heat shock 70-kDa protein

Elevation of heat-shock protein expression, known as cellular heat-shock responses, occurs during infection of many viruses, which is involved in viral replication through various mechanisms. Herein, transcriptome analysis revealed that over-expression of non-structural protein NS31 of grass carp reovirus (GCRV) in grass carp Ctenopharyngodon idellus kidney (CIK) cells specifically induced expression of heat-shock response (HSR) genes HSP30 and HSP70. We further found that, among the HSR genes, only HSP70 protein were shown to be efficiently induced in fish cells following NS31 over-expression or GCRV infection. Employing a luciferase assay, we were able to show that the promoter of the HSP70 gene can be specifically activated by NS31. In addition, over-expressing HSP70 in grass carp CIK cells resulted in enhanced replication efficiency of GCRV, and an inhibitor for HSP70 resulted in the inhibition of GCRV replication, indicating that HSP70 should serve as a pro-viral factor. We also found that NS31 could activate HSP70 expression in cells of other vertebrate animals. Similar inducing effect on HSP70 expression was demonstrated for NS31-homologue proteins of other aquareoviruses including American grass carp reovirus (AGCRV) and GRCV (green river chinook virus). All these results indicated NS31 proteins in the Aquareovirus genus should play a key role for up-regulating specific HSP70 gene during viral replication.

Hepatitis C Virus Infection of Human Thyrocytes: Metabolic, Hormonal, and Immunological Implications

CONTEXT

Hepatitis C virus (HCV) infection is a prevalent disease worldwide. Thyroid dysfunction is one of the most common extrahepatic manifestations of HCV infection. We hypothesized that HCV can directly infect human thyrocytes thereby causing thyroid dysfunction.

SETTING

Human thyrocytes in primary cell culture, ML-1 human thyroid cell line, and Huh7.5 human hepatocyte cell line were infected with HCV using the Huh7.5JFH1 cell line that releases infectious HCV virions. After infection, the release of new virions, production of proinflammatory cytokines, and expression of miR-122 were evaluated. Ribonucleic acid (RNA) extracted from HCV-infected cells and mock-infected cells was subjected to RNA sequencing and transcriptomic analysis. Ingenuity pathway analysis was used to detect up- and down-regulated pathways.

RESULTS

Human thyrocytes express major HCV entry factors including CD81, occludin, claudin-1, and scavenger receptor class B1. Viral infection of thyroid cells was confirmed by detection of HCV core protein in supernatants and negative-sense HCV RNA in cell lysates. HCV infection of thyrocytes induced the production of the chemokine CXCL-8 and the proinflammatory cytokines tumor necrosis factor alpha (TNF-α) and significantly increased the expression of miR-122. Moreover, HCV infection of thyrocytes decreased expression of the thyroid peroxidase and thyroglobulin genes and increased expression of the deiodinase 2 gene. The top upregulated pathways in HCV-infected thyrocytes were immune pathways and metabolic pathways, while infected hepatocytes upregulated lipid and glucose metabolism pathways as previously reported.

CONCLUSIONS

HCV infection may induce thyroid dysfunction by different mechanisms including direct infection of thyrocytes leading to activation of inflammatory pathways and upregulation of miR-122. These findings support a general mechanism for viral induction of autoimmunity through direct infection of target tissues.

Upregulation of HLA Class I and Antiviral Tissue Responses in Hashimoto's Thyroiditis

Background: Hashimoto's thyroiditis (HT) is a common autoimmune disease of unknown origin. However, viral infections have been implicated as triggers for autoimmunity. Human leukocyte antigen (HLA) class I presents antigens to circulating immune cells and plays a crucial role in the defense against viral infections. This study aimed to investigate the presence of enterovirus and HLA class I expression in one of the largest HT thyroid tissue cohorts to date. In addition, viral receptors and viral immune response proteins were examined. Methods: Thyroid tissue samples from 46 HT patients were obtained using core needle biopsy. Thyroid tissue collected during neck surgery for other reasons than thyroid autoimmunity served as controls. Standard immunohistochemistry on formalin-fixed, paraffin-embedded tissue samples were used to detect HLA class I, enteroviral capsid protein 1 (VP1), and coxsackie and adenovirus receptor (CAR) in thyroid cells. A subset of the samples was examined with combined immunofluorescence staining for signal transducer and activator of transcription 1 (STAT1) and protein kinase R (PKR). Results: Significantly more HLA class I-positive samples were found in the HT group (31 out of 46 [67.4%]) than in the control group (5 out of 24 [20.8%]) (p < 0.001). Moreover, the semiquantitative score assessing the grade of HLA class I expression was significantly higher in the HT group (3.9 ± 3.1) than in the control group (0.5 ± 0.9) (p < 0.001). In addition, STAT1 was colocalized with HLA class I, and PKR and VP1 were also found and were colocalized together. VP1 was detected in both controls and the HT samples, with slightly more VP1⁺ thyroid cells in the HT samples (20.1% ± 16.4%) than in controls (14.9% ± 10.5%). Finally, the presence of CAR in thyroid cells was confirmed. Conclusion: The current study confirmed that HLA class I hyperexpression is a defining feature of HT. Thyroid cells express CAR, thus making them susceptible to enterovirus infection. The colocalization of HLA class I with STAT1 and VP1 with PKR indicates an intracellular, antiviral host response. These findings support the concept of a firm link between viral infection and autoimmune thyroid diseases.

Induction of Chemokines by Hepatitis C Virus Proteins: Synergy of the Core Protein with Interleukin-1β and Interferon-γ in Liver Bystander Cells

Chronic hepatitis C virus (HCV) infection accounts for a large proportion of hepatic fibrosis and carcinoma cases observed worldwide. Mechanisms involved in HCV-induced hepatic injury have yet to be fully elucidated. Of particular interest is the capacity of HCV to regulate inflammatory responses. Here, we reveal modulation of cytokine activity by the HCV proteins non-structural protein 3 (NS3), glycoprotein E2, and core protein for their ability to induce chemokine expression in various liver bystander cells. Chemokines sustain chronic liver inflammation and relay multiple fibrogenic effects. CCL2, CCL3, CCL20, CXCL8, and CXCL10 were differentially expressed after treatment of monocytes, fibroblasts, or liver sinusoidal microvascular endothelial cells (LSECs) with HCV proteins. In comparison to NS3 and glycoprotein E2, core protein was a stronger inducer of chemokines in liver bystander cells. Interferon-γ (IFN-γ) and interleukin-1β (IL-1β) synergized with core protein to induce CCL2, CCL20, CXCL8, or CXCL10 in fibroblasts or LSECs. These findings reveal new mechanisms of hepatic injury caused by HCV.

Graves' disease: Epidemiology, genetic and environmental risk factors and viruses

Graves' disease (GD) is the most common cause of hyperthyroidism in developed Countries. It is more common between 30 and 60 years; 5-10 times more frequent in women. The genetic predisposition accounts for 79% of the risk for GD, while environmental factors for 21%. About 70% of genes associated with autoimmune thyroid disorders (AITD) are implicated in T-cell function. Among GD endogenous factors, estrogens, X-inactivation and microchimerism are important. Among environmental risk factors, smoking, iodine excess, selenium and vitamin D deficiency, and the occupational exposure to Agent Orange have been associated with GD. Many studies showed that HCV is associated with thyroid autoimmunity and hypothyroidism, in patients with chronic HCV hepatitis (CHC); a significant link has been shown also between HCV-related mixed cryoglobulinemia and risk for GD. Moreover, IFN-α-treated CHC patients develop GD more frequently. Novel studies are needed about possible risk factors to reduce the occurence of GD in West Countries.

Autoimmune Thyroiditis and Myasthenia Gravis

Autoimmune diseases (AIDs) are the result of specific immune responses directed against structures of the self. In normal conditions, the molecules recognized as "self" are tolerated by immune system, but when the self-tolerance is lost, the immune system could react against molecules from the body, causing the loss of self-tolerance, and subsequently the onset of AID that differs for organ target and etiology. Autoimmune thyroid disease (ATD) is caused by the development of autoimmunity against thyroid antigens and comprises Hashimoto's thyroiditis and Graves disease. They are frequently associated with other organ or non-organ specific AIDs, such as myasthenia gravis (MG). In fact, ATD seems to be the most associated pathology to MG. The etiology of both diseases is multifactorial and it is due to genetic and environmental factors, and each of them has specific characteristics. The two pathologies show many commonalities, such as the organ-specificity with a clear pathogenic effect of antibodies, the pathological mechanisms, such as deregulation of the immune system and the implication of the genetic predisposition. They also show some differences, such as the mode of action of the antibodies and therapies. In this review that focuses on ATD and MG, the common features and the differences between the two diseases are discussed.