Letter: Yersinia enterocolitica infection and thyroid disorders

Unexpected Crosslinking Effects of a Human Thyroid Stimulating Monoclonal Autoantibody, M22, with IGF1 on Adipogenesis in 3T3L-1 Cells

To study the effects of the crosslinking of IGF1 and/or the human thyroid-stimulating monoclonal autoantibody (TSmAb), M22 on mouse adipocytes, two- and three-dimensional (2D or 3D) cultures of 3T3-L1 cells were prepared. Each sample was then subjected to the following analyses: (1) lipid staining, (2) a real-time cellular metabolic analysis, (3) analysis of the mRNA expression of adipogenesis-related genes and extracellular matrix (ECM) molecules including collagen (Col) 1, 4 and 6, and fibronectin (Fn), and (4) measurement of the size and physical properties of the 3D spheroids with a micro-squeezer. Upon adipogenic differentiation (DIF+), lipid staining and the mRNA expression of adipogenesis-related genes in the 2D- or 3D-cultured 3T3-L1 cells substantially increased. On adding IGF1 but not M22 to DIF+ cells, a significant enhancement in lipid staining and gene expressions of adipogenesis-related genes was detected in the 2D-cultured 3T3-L1 cells, although some simultaneous suppression or enhancement effects by IGF1 and M22 against lipid staining or Fabp4 expression, respectively, were detected in the 3D 3T3-L1 spheroids. Real-time metabolic analyses indicated that monotherapy with IGF1 or M22 shifted cellular metabolism toward energetic states in the 2D 3T3-L1 cells upon DIF+, although no significant metabolic changes were induced by DIF+ alone in 2D cultures. In addition, some synergistical effects on cellular metabolism by IGF1 and M22 were also observed in the 2D 3T3-L1 cells as well as in cultured non-Graves' orbitopathy-related human orbital fibroblasts (n-HOFs), but not in Graves' orbitopathy-related HOFs (GHOFs). In terms of the physical properties of the 3D 3T3-L1 spheroids, (1) their sizes significantly increased upon DIF+, and this increase was significantly enhanced by the presence of both IGF1 and M22 despite downsizing by monotreatment, and (2) their stiffness increased substantially, and no significant effects by IGF-1 and/or M22 were observed. Regarding the expression of ECM molecules, (1) upon DIF+, significant downregulation or upregulation of Col1 and Fn (3D), or Col4 and 6 (2D and 3D) were observed, and (2) in the presence of IGF-1 and/or M22, the mRNA expression of Col4 was significantly downregulated by M22 (2D and 3D), but the expression of Col1 was modulated in different manners by monotreatment (upregulation) or the combined treatment (downregulation) (3D). These collective data suggest that the human-specific TSmAb M22 induced some unexpected simultaneous crosslinking effects with IGF-1 with respect to the adipogenesis of 2D-cultured 3T3-L1 cells and the physical properties of 3D 3T3-L1 spheroids.

Anti-Idiotypic Agonistic Antibodies: Candidates for the Role of Universal Remedy

Anti-idiotypic antibodies (anti-IDs) were discovered at the very beginning of the 20th century and have attracted attention of researchers for many years. Nowadays, there are five known types of anti-IDs: α, β, γ, ε, and δ. Due to the ability of internal-image anti-IDs to compete with an antigen for binding to antibody and to alter the biologic activity of an antigen, anti-IDs have become a target in the search for new treatments of autoimmune illnesses, cancer, and some other diseases. In this review, we summarize the data about anti-IDs that mimic the structural and functional properties of some bioregulators (autacoids, neurotransmitters, hormones, xenobiotics, and drugs) and evaluate their possible medical applications. The immune system is potentially able to reproduce or at least alter the effects of any biologically active endogenous or exogenous immunogenic agent via the anti-idiotypic principle, and probably regulates a broad spectrum of cell functions in the body, being a kind of universal remedy or immunacea, by analogy to the legendary ancient goddess of universal healing Panacea (Πανάκεια, Panakeia in Greek) in the treatment and prevention of diseases, possibly including non-infectious somatic and even hereditary ones.

Is Graves' disease a primary immunodeficiency? New immunological perspectives on an endocrine disease

BACKGROUND

Uncertainty about factors influencing the susceptibility and triggers for Graves' disease persists, along with a wide variation in the response to anti-thyroid drugs, currently at approximately 50% of non-responders. The aim of this narrative review is to summarize immunological concepts, with a combined endocrine and immunological perspective, to highlight potential new areas of research.

MAIN TEXT

Relevant studies were identified through a systematic literature search using the PubMed and EMBASE databases in March 2016. No cut-offs regarding dates were imposed. We used the terms "Graves' Disease" or "Basedow" or "thyrotoxicosis" together with the terms "etiology", "pathophysiology", "immunodeficiency", "causality", and "autoimmunity". The terms "orbitopathy", "ophthalmopathy", and "amiodarone" were excluded. Articles in English, French, German, Croatian, Spanish, and Italian were eligible for inclusion.

CONCLUSIONS

While concepts such as the impact of iodine, smoking, human leucocyte antigen, infections, and ethnicity are established, new ideas have emerged. Pertaining evidence suggests the involvement of autoimmunity and immunodeficiency in the pathophysiology of Graves' disease. Recent studies point to specific immunological mechanisms triggering the onset of disease, which may also serve as targets for more specific therapies.

The microbiota and autoimmunity: Their role in thyroid autoimmune diseases

Since the 1970s, the role of infectious diseases in the pathogenesis of Graves' disease (GD) has been an object of intensive research. The last decade has witnessed many studies on Yersinia enterocolitica, Helicobacter pylori and other bacterial organisms and their potential impact on GD. Retrospective, prospective and molecular binding studies have been performed with contrary outcomes. Until now it is not clear whether bacterial infections can trigger autoimmune thyroid disease. Common risk factors for GD (gender, smoking, stress, and pregnancy) reveal profound changes in the bacterial communities of the gut compared to that of healthy controls but a pathogenetic link between GD and dysbiosis has not yet been fully elucidated. Conventional bacterial culture, in vitro models, next generation and high-throughput DNA sequencing are applicable methods to assess the impact of bacteria in disease onset and development. Further studies on the involvement of bacteria in GD are needed and may contribute to the understanding of pathogenetic processes. This review will examine available evidence on the subject.

Molecular mimicry and autoimmune thyroid disease

Hypothesized 40 years ago, molecular mimicry has been thereafter demonstrated as an extremely common mechanism by which microbes elude immune response and modulate biosynthetic/metabolic pathways of the host. In genetically predisposed persons and under particular conditions, molecular mimicry between microbial and human antigens can turn a defensive immune response into autoimmunity. Such triggering role and its pathogenetic importance have been investigated and demonstrated for many autoimmune diseases. However, this is not the case for autoimmune thyroid disease, which appears relatively neglected by this field of research. Here we review the available literature on the possible role of molecular mimicry as a trigger of autoimmune thyroid disease. Additionally, we present the results of in silico search for amino acid sequence homologies between some microbial proteins and thyroid autoantigens, and the potential pathogenetic relevance of such homologies. Relevance stems from the overlap with known autoepitopes and the occurrence of specific HLA-DR binding motifs. Bioinformatics data published by our group support and explain the triggering role of Borrelia, Yersinia, Clostridium botulinum, Rickettsia prowazekii and Helicobacter pylori. Our new data suggest the potential pathogenic importance of Toxoplasma gondii, some Bifidobacteria and Lactobacilli, Candida albicans, Treponema pallidum and hepatitis C virus in autoimmune thyroid disease, indicating specific molecular targets for future research. Additionally, the consistency between in silico prediction of cross-reactivity and experimental results shows the reliability and usefulness of bioinformatics tools to precisely identify candidate molecules for in vitro and/or in vivo experiments, or at least narrow down their number.

Breaking tolerance to thyroid antigens: changing concepts in thyroid autoimmunity

Thyroid autoimmunity involves loss of tolerance to thyroid proteins in genetically susceptible individuals in association with environmental factors. In central tolerance, intrathymic autoantigen presentation deletes immature T cells with high affinity for autoantigen-derived peptides. Regulatory T cells provide an alternative mechanism to silence autoimmune T cells in the periphery. The TSH receptor (TSHR), thyroid peroxidase (TPO), and thyroglobulin (Tg) have unusual properties ("immunogenicity") that contribute to breaking tolerance, including size, abundance, membrane association, glycosylation, and polymorphisms. Insight into loss of tolerance to thyroid proteins comes from spontaneous and induced animal models: 1) intrathymic expression controls self-tolerance to the TSHR, not TPO or Tg; 2) regulatory T cells are not involved in TSHR self-tolerance and instead control the balance between Graves' disease and thyroiditis; 3) breaking TSHR tolerance involves contributions from major histocompatibility complex molecules (humans and induced mouse models), TSHR polymorphism(s) (humans), and alternative splicing (mice); 4) loss of tolerance to Tg before TPO indicates that greater Tg immunogenicity vs TPO dominates central tolerance expectations; 5) tolerance is induced by thyroid autoantigen administration before autoimmunity is established; 6) interferon-α therapy for hepatitis C infection enhances thyroid autoimmunity in patients with intact immunity; Graves' disease developing after T-cell depletion reflects reconstitution autoimmunity; and 7) most environmental factors (including excess iodine) "reveal," but do not induce, thyroid autoimmunity. Micro-organisms likely exert their effects via bystander stimulation. Finally, no single mechanism explains the loss of tolerance to thyroid proteins. The goal of inducing self-tolerance to prevent autoimmune thyroid disease will require accurate prediction of at-risk individuals together with an antigen-specific, not blanket, therapeutic approach.

Yersinia enterocolitica provides the link between thyroid-stimulating antibodies and their germline counterparts in Graves' disease

Graves' disease results from thyroid-stimulating Abs (TSAbs) activating the thyrotropin receptor (TSHR). How TSAbs arise from early precursor B cells has not been established. Genetic and environmental factors may contribute to pathogenesis, including the bacterium Yersinia enterocolitica. We developed two pathogenic monoclonal TSAbs from a single experimental mouse undergoing Graves' disease, which shared the same H and L chain germline gene rearrangements and then diversified by numerous somatic hypermutations. To address the Ag specificity of the shared germline precursor of the monoclonal TSAbs, we prepared rFab germline, which showed negligible binding to TSHR, indicating importance of somatic hypermutation in acquiring TSAb activity. Using rFab chimeras, we demonstrate the dominant role of the H chain V region in TSHR recognition. The role of microbial Ags was tested with Y. enterocolitica proteins. The monoclonal TSAbs recognize 37-kDa envelope proteins, also recognized by rFab germline. MALDI-TOF identified the proteins as outer membrane porin (Omp) A and OmpC. Using recombinant OmpA, OmpC, and related OmpF, we demonstrate cross-reactivity of monoclonal TSAbs with the heterogeneous porins. Importantly, rFab germline binds recombinant OmpA, OmpC, and OmpF confirming reactivity with Y. enterocolitica. A human monoclonal TSAb, M22 with similar properties to murine TSAbs, also binds recombinant porins, showing cross-reactivity of a spontaneously arising pathogenic Ab with Y. enterocolitica. The data provide a mechanistic framework for molecular mimicry in Graves' disease, where early precursor B cells are expanded by Y. enterocolitica porins to undergo somatic hypermutation to acquire a cross-reactive pathogenic response to TSHR.

No causal relationship between Yersinia enterocolitica infection and autoimmune thyroid disease: evidence from a prospective study

The objective of this study was to evaluate prospectively the relationship between Yersinia enterocolitica (YE) infection and the development of overt autoimmune hypo- or hyperthyroidism (study A) and the de novo occurrence of thyroid antibodies (study B). This was a prospective cohort study of 790 euthyroid women who were first- or second-degree relatives of autoimmune thyroid disease (AITD) patients. Follow-up was 5 years, with annual assessments. Study A was a nested case-control study in which YE serological status was measured between cases {subjects who developed overt hypothyroidism [thyroid stimulating hormone (TSH) > 5·7 mU/l and free T4 (FT4) < 9·3 pmol/l] or overt hyperthyroidism (TSH < 0·4 mU/l and FT4 > 20·1 pmol/l)} and matched controls. For study B, 388 euthyroid women without thyroid antibodies at baseline were enrolled. The YE serological status was compared between subjects who developed thyroid peroxidase (TPO)-antibodies and/or thyroglobulin (Tg)-antibodies at 4-year follow-up and those who remained negative. For study A, the proportion of subjects positive for Yersinia enterocolitica outer membrane protein (YOP) immunoglobulin (Ig)G or YOP IgA did not differ between cases and controls at baseline. One year before the development of overt hypo- or hyperthyroidism, the proportion of subjects with YOP IgG was not different between cases and controls, but YOP IgA were less prevalent in cases. For study B, de novo occurrence of TPO (or TPO-antibodies and/or Tg-antibodies) did not differ between subjects in whom YOP IgG were positive or negative at baseline. Neither persistence nor emergence of YOP IgG at 4-year follow-up was associated with the occurrence of TPO-antibodies or Tg-antibodies. Similar results were observed with respect to YOP IgA. YE infection does not contribute to an increased risk of thyroid autoimmunity.

Identification of outer membrane porin f protein of Yersinia enterocolitica recognized by antithyrotopin receptor antibodies in Graves' disease and determination of its epitope using mass spectrometry and bioinformatics tools

CONTEXT

In addition to genetic susceptibility, Yersinia enterocolitica (YE) infection played an important causative role in the pathogenesis of Graves' disease (GD) through molecular mimicry. However, the specific YE proteins and epitopes recognized by anti-TSH receptor (TSHR) autoantibodies (TRAb) have not been fully clarified, resulting in conflicting results from clinical research.

OBJECTIVE

Our aim was to explore the roles of YE in the pathogenesis of GD and identify the YE proteins and epitopes that are similar to the TSHR and are recognized by TRAb.

DESIGN

Assays of YE antibodies, TRAb, thyroglobulin antibodies, and thyroid microsomal antibodies as well as cross-absorption and two-way immunodiffusion were performed in patients with GD. Using mass spectrometry and the bioinformatics tools of protein structure modeling and epitope prediction, we identified the YE protein and its epitope, which was recognized by TRAb and was similar to TSHR.

RESULTS

Our study demonstrated for the first time that the YE protein outer membrane porin F protein (ompF) shared cross-immunogenicity with a leucine-rich domain of TSHR. The epitope recognized by antihuman TSHR antibody is located within the ompF region of amino acids 190-197, and the polyantibody against ompF protein showed TSAb activity.

CONCLUSIONS

Our results suggest that YE ompF is involved in the production of TRAb and the pathogenesis of GD through molecular mimicry. These findings are potentially important for understanding the role molecular mimicry plays in the disturbance of immune tolerance and the induction of autoimmunity to the TSHR.

Prolonged monosymptomatic fever due to Yersinia enterocolitica

A previously healthy 14-year-old girl showed monosymptomatic hectic fever for over 3 weeks with negative clinical findings. Extensive laboratory investigation revealed only elevated ESR and a high titer of agglutinating antibodies against Yersinia enterocolitica, serotype 0-3. These abnormalities disappeared upon tetracycline therapy, after which she remained in excellent health. This unusual manifestation of yersiniosis, which was of unknown source, demonstrates that Yersinia infection should be considered in patients with prolonged febrile illnesses of obscure etiology.

Serological evidence for the role of bacterial infections in the pathogenesis of thyroid diseases

Subacute thyroiditis is generally believed to be of viral origin, and infection is also suspected of playing a role as a triggering factor in the pathogenesis of autoimmune thyroid diseases. We have measured a broad spectrum of bacterial and viral antibodies in paired sera of 32 patients with thyroid disease of recent onset. The data indicate a preceding infection in 14 (44%) of the patients, enterobacterial in 5, streptococcal in 4 and staphylococcal in 2. A viral infection was suggested in 6 patients, in each case caused by different agents; 3 of them also showed evidence of a bacterial infection. Patients with positive microbial serology were found in all diagnostic groups, including subacute thyroiditis, Graves' disease and Hashimoto's disease. These results suggest an association between a preceding bacterial infection and the development of thyroid disease in some patients.

Too early to dismiss Yersinia enterocolitica infection in the aetiology of Graves' disease: evidence from a twin case-control study

BACKGROUND

Yersinia enterocolitica (YE) infection has long been implicated in the pathogenesis of Graves' disease (GD). The association between YE and GD could, however, also be due to common genetic or environmental factors affecting the development of both YE infection and GD. This potential confounding can be minimized by investigation of twin pairs discordant for GD.

AIM

To examine whether YE infection is associated with GD.

DESIGN

We first conducted a classical case-control study of individuals with (61) and without (122) GD, and then a case-control study of twin pairs (36) discordant for GD.

METHODS

Immunoglobulin (Ig)A and IgG antibodies to virulence-associated Yersinia outer membrane proteins (YOPs) were measured.

MAIN OUTCOME MEASURES

The prevalence of YOP IgA and IgG antibodies.

RESULTS

Subjects with GD had a higher prevalence of YOP IgA (49%vs. 34%, P = 0.054) and YPO IgG (51%vs. 35%, P = 0.043) than the external controls. The frequency of chronic YE infection, reflected by the presence of both IgA and IgG YOP antibodies, was also higher among cases than controls (49%vs. 33%, P = 0.042). Similar results were found in twin pairs discordant for GD. In the case-control analysis, individuals with GD had an increased odds ratio (OR) of YE infection: IgA 1.84 (95% CI 0.99-3.45) and IgG 1.90 (95% CI 1.02-3.55). In the co-twin analysis, the twin with GD also had an increased OR of YE infection: IgA 5.5 (95% CI 1.21-24.81) and IgG 5.0 (95% CI 1.10-22.81).

CONCLUSION

The finding of an association between GD and YE in the case-control study and within twin pairs discordant for GD supports the notion that YE infection plays an aetiological role in the occurrence of GD, or vice versa. Future studies should examine the temporal relationship of this association in more depth.

Yersinia enterocolitica infection does not confer an increased risk of thyroid antibodies: evidence from a Danish twin study

Understanding of the aetiological basis of thyroid autoimmunity may be gained by studying the early stages of the disease process. We aimed to (1) investigate the relationship between thyroid antibody status and Yersinia enterocolitica (YE) infection in euthyroid subjects and (2) explore the relative importance of genetic and environmental risk factors in the acquisition of YE infection. The association between thyroid antibody status and YE infection was explored using a case-control design. Furthermore, thyroid antibody-positive twins were compared with their thyroid antibody-negative co-twin. In 468 twins, IgA and IgG antibodies to virulence-associated outer-membrane proteins (YOPs) of YE were measured. Of these, 147 were thyroid antibody-positive (cases). A total of 147 age- and gender-matched twins were chosen as controls. The prevalence of YOP antibodies was lower among thyroid antibody-positive individuals than among controls. Yersinia infection was not associated with a positive thyroid antibody status: the odds ratio (with 95% CI) for YOP IgA-ab was 0.66 (0.42-1.05), P = 0.078 and for YOP IgG-ab it was 0.95 (0.60-1.50), P = 0.816. Within discordant twin pairs, the thyroid antibody-positive twin did not have an increased risk of Yersinia infection compared to the thyroid antibody-negative co-twin [odds ratio: YOP IgA-Ab: 0.94 (0.49-1.83), P = 0.866, and YOP IgG-Ab: 1.35 (0.72-2.53), P = 0.345]; 41% (95% CI 10-67% of the liability of being YOP antibody-positive was due to genetic effects. In conclusion, Yersinia infection does not confer an increased risk of thyroid antibodies. The genetic contribution in the acquisition of Yersinia infection is modest.

Further evidence for a strong genetic influence on the development of autoimmune thyroid disease: the California twin study

To determine the heritable component of Graves' disease (GD) more precisely, a disease survey questionnaire completed by 13,726 California-born twin pairs over the age of 37 years was used as the foundation of this study. On the basis of this survey, each member of pairs reporting a past diagnosis of GD was then sought for an extensive telephone interview to seek diagnostic confirmation. Successful diagnostic evaluation occurred in 108 cases, of which 99 affected twin pairs form the basis of this report. The results indicate that the estimated pairwise concordance for is 17% in monozygotic (MZ) twins, and 1.9% in dizygotic (DZ) twins, which are in close agreement with a recent report from a Danish twin population. Moreover, the reported 3.9% occurrence of GD found in the first-degree relatives of affected twin pairs supports these findings. In contrast, only 0.45% of all twins, 0.27% of the spouses of twins, and approximately 0.16% of the first-degree relatives of unaffected twins were reported to have GD. Additionally, among the unaffected MZ twins of patients with GD, 17% reported having chronic thyroiditis and 10% other nonthyroid autoimmune conditions such as lupus erythematosus, pernicious anemia, or idiopathic thrombocytopenic purpura. Thus, a genetic predisposition appears to be shared for both thyroid and some nonthyroid autoimmune diseases. While it seems that GD is a strongly and nonspecifically heritable condition, the relatively low level of twin concordance indicates that this disease likely requires a nonheritable etiologic determinant(s) as well.

Prevalence of Yersinia plasmid-encoded outer protein (Yop) class-specific antibodies in patients with Hashimoto's thyroiditis

OBJECTIVE

To investigate the prevalence of class-specific antibodies (IgG, IgA) to Yersinia enterocolitica plasmid-encoded outer proteins (Yops) in patients with diagnosed Hashimoto's thyroiditis.

METHODS

Seventy-one patients with Hashimoto's disease, 464 healthy blood donors and 250 patients with non-postinfectious rheumatic disorders (matched controls) were tested for class-specific antibodies to Yops. Anti-Yop antibodies were determined by ELISA and Western blot.

RESULTS

The prevalence of class-specific antibodies to Yops as determined by ELISA was 14-fold higher (20 of 71; 28.2%) in people with Hashimoto's thyroiditis than in the two control groups. These results were confirmed by the Western blot, with 16 positive sera, three equivocal and one negative.

CONCLUSIONS

There is strong clinical and seroepidemiologic evidence for an immunopathologic causative relationship between Yersinia enterocolitica infection and Hashimoto's thyroiditis. Further investigation concerning the mechanisms involved and the possible effects of antibacterial chemotherapy on the outcome of Hashimoto's disease is warranted.

Helicobacter pylori infection is markedly increased in patients with autoimmune atrophic thyroiditis

Infection by viral or bacterial pathogens has been suspected in playing a role in the development of autoimmune thyroid disease. Because Helicobacter pylori might be involved in the development of nongastrointestinal conditions such as rosacea, ischemic heart disease, and diabetes mellitus, we evaluated the prevalence of H. pylori infection in patients with autoimmune thyroid disease. Fifty-nine patients with autoimmune thyroid disease were included: autoimmune atrophic thyroiditis (n=21), Hashimoto's thyroiditis (n=18), and Graves' disease (n=20). Twenty patients with nontoxic multinodular goiter served as controls for nonautoimmune thyroid disease, and 11 patients with Addison's disease served as controls for nonthyroid endocrine autoimmune disease. The levels of anti-H. pylori immunoglobulin G (IgG) were determined, and a radiolabeled urea breath test were performed. The prevalence of H. pylori infection was markedly increased in the patients with autoimmune atrophic thyroiditis (85.7%), compared with the controls with nontoxic multinodular goiter (40%) and Addison's disease (45.4%). Infection by H. pylori resulted in increased levels of gastrin, pepsinogen I, and pepsinogen II in the H. pylori-positive groups, compared with the H. pylori-negative groups. A positive linear regression was found between the levels of microsomal autoantibodies and those of anti-H. pylori IgG in patients with autoimmune atrophic thyroiditis (n=21; r=0.79; p < 0.01). Finally, and although the overall prevalence of H. pylori infection was not increased, the anti-H. pylori IgG levels and the results from the breath test were higher in the patients with Graves' disease and Hashimoto's thyroiditis patients than in the controls. Clearly, the prevalence of H. pylori infection is increased in autoimmune atrophic thyroiditis and results in abnormalities of gastric secretory function. The strong relation between the levels of anti-H. pylori IgG and the levels of microsomal antibodies suggests that H. pylori antigens might be involved in the development of autoimmune atrophic thyroiditis or that autoimmune function in autoimmune atrophic thyroiditis may increase the likelihood of H. pylori infection.

Yersinia enterocolitica: the charisma continues

Yersinia enterocolitica, a gram-negative coccobacillus, comprises a heterogeneous group of bacterial strains recovered from animal and environmental reservoirs. The majority of human pathogenic strains are found among distinct serogroups (e.g. O:3, O:5,27, O:8, O:9) and contain both chromosome- and plasmid (60 to 75 kb)-mediated virulence factors that are absent in "avirulent" strains. While Y. enterocolitica is primarily a gastrointestinal tract pathogen, it may produce extraintestinal infections in hosts with underlying predisposing factors. Postinfection sequelae include arthritis and erythema nodosum, which are seen mainly in Europe among patients with serogroups O:3 and O:9 infection and HLA-B27 antigen. Y. enterocolitica is acquired through the oral route and is epidemiologically linked to porcine sources. Bacteremia is prominent in the setting of immunosuppression or in patients with iron overload or those being treated with desferrioxamine. metastatic foci following bacteremia are common and often involve the liver and spleen. Of particular concern is blood transfusion-related bacteremia. Evidence has accumulated substantiating the role of Y. enterocolitica as a food-borne pathogen that has caused six major outbreaks in the United States. The diagnosis of Y. enterocolitica gastroenteritis is best achieved through isolation of the bacterium on routine or selective bacteriologic media. When necessary, serogrouping, biogrouping, and assessment for plasmid-encoded virulence traits may aid in distinguishing virulent from "avirulent" strains. Epidemiologically, outside of identified food-borne outbreaks, the source (reservoir) of Y. enterocolitica in sporadic cases is speculative. Therefore, prevention and control measures are difficult to institute.

A survey of acute and chronic disease associated with Yersinia enterocolitica infection. A Norwegian 10-year follow-up study on 458 hospitalized patients

The aim of the present study was to further elucidate acute and chronic manifestations of Yersinia enterocolitica infection. During the period 1974-83, 458 hospitalized patients were diagnosed by antibody response and/or isolation of the microorganism. 64 patients had suffered from chronic conditions as rheumatic disease, inflammatory bowel disease, hepatitis, nephritis or thyroid disease for some time. Acute hepatic, renal, cardiac, pulmonary, pancreatic or neurologic involvement were observed in a substantial portion of patients; several had multiorgan disease. Acute insulin-dependent diabetes was seen in 2 patients, malignant mesothelioma in 2, and specific lymph node inflammation in 1. The patients were followed for 4-14 years (1987). 36/160 readmitted patients had abdominal pain and 26 had diarrhea; chronic colitis was demonstrated in 4. Some patients developed rheumatic conditions; others developed chronic disease of liver, kidneys, heart, pancreas, thyroid or nervous system. Chronic liver disease, in 22 patients, was correlated with positive tests for antinuclear antibody and rheumatoid factor; and might influence development of malignant disease, and mortality. A variety of acute and chronic clinical pictures may be associated with Y. enterocolitica infection, and further clinical research is required in this field.

Receptor autoimmunity in endocrine disorders

The discovery in 1956 of the long-acting thyroid stimulator of Graves' disease, now known as thyroid-stimulating antibodies, was seminal. A new mechanism for disease was revealed that appears applicable to virtually all endocrine systems, involving the growth as well as the function of endocrine cells. An endocrine gland may fail through at least three autoimmune mechanisms: destruction, atrophy, and inhibition of function. Destruction is probably irreversible but is not usually distinguishable clinically from receptor blockade causing atrophy or from metabolic unresponsiveness. The contribution made by receptor autoimmunity to endocrine diseases other than thyroid disease is at present unclear, but with immunologic manipulation it is potentially reversible, improving the replicative capacity of the gland, its metabolic responsiveness, or both.

Secretor status and infection in patients with Graves' disease

We have demonstrated that the inability to secrete the water soluble glycoprotein form of the ABO blood group antigens into saliva is significantly more common in patients with Graves' disease than control subjects (40% vs 27%: P less than 0.025) but not among those with Hashimoto's thyroiditis or spontaneous primary atrophic hypothyroidism. Non-secretion is associated with increased susceptibility to infection and to asymptomatic carriage of some microorganisms. Although Yersinia enterocolitica has been found to express antigen cross reactive with the TSH receptor, we did not find an increased prevalence of Yersinia species in the faeces of 107 patients with Graves' disease. The isolation rate (less than 1%) was similar to that observed in the local population with diarrhoeal illness. Salivary IgA levels determined by whole cell ELISA with Y. enterocolitica 03 were not elevated in the majority of specimens examined. The results suggest that in contrast to reports from Scandinavia, there is no strong evidence that yersiniae play a role in the pathogenesis of Graves' disease among patients in South east Scotland. Non-secretors are significantly over represented among patients with several other autoimmune diseases; however, with the exception of antitubulin antibodies, non-secretors with Graves' disease did not have more antibodies to other human antigens than secretor patients.

Yersinia enterocolitica and thyroid autoimmunity

The concordance rate of Graves' disease in pairs of identical twins of 30 to 60% points to the influence of environmental factors, and infections have often been incriminated in the pathogenesis. More than 15 years ago we demonstrated an increased frequency of antibodies to Yersinia enterocolitica (Y. ent.) serotype 3, which later was confirmed by others, suggesting a link between infection with Y. ent. and autoimmune thyroid diseases.

Cell-mediated immunity of Yersinia enterocolitica serotype 3 in patients with thyroid diseases

The cellular immunity to Yersinia enterocolitica serotype 3 and crude human thyroid extract in 64 patients with thyroid diseases and 25 controls was studied by the leucocyte migration test. In the patient group as a whole and in patients with Graves' disease and nontoxic diffuse goitre a significantly reduced leucocyte migration towards Yersinia was found when compared with the controls. In controls the migration index was not related to the presence or titre of circulating yersinia antibodies, whereas the migration index of patients with yersinia antibodies was lower than the migration index of patients without yersinia antibodies as well as that of the controls. The leucocyte migration inhibition in two patients with recent yersinosis was normal during the recovery phase. In the presence of thyroid extract leucocyte migration inhibition differed only significantly in Graves' disease. However, a significantly positive correlation between inhibition of migration by thyroid extract and by Yersinia was found, while no correlation could be demonstrated in the controls. The cell-mediated immunity towards Yersinia in thyroid diseases thus demonstrated adds further evidence to the association between Yersinia and thyroid disease.

Ocular involvement in Yersinia enterocolitica infection presenting as Parinaud's oculoglandular syndrome

Ocular involvement in Yersinia enterocolitica infection presenting as a Parinaud's oculoglandular syndrome occurred in a 77-year-old woman with diabetes. Yersinia enterocolitica was recovered from cultures of the conjunctiva, cornea, fistula tract, and blood. The patient responded to parenteral and topical administration of gentamicin and a corneal transplant. While hospitalized, she developed peritonsillar inflammation and enlarged, tender lymph nodes in the preauricular, submaxillary, and submandibular areas. The combination of the unilateral granulomatous conjunctivitis and enlarged regional lymph nodes was consistent with the diagnosis of Parinaud's oculoglandular syndrome. Yersinia enterocolitica may be another cause of Parinaud's oculoglandular syndrome.