Immunology of Endocrine Gland Diseases بنام خدا Immunology of Endocrine Gland Diseases Dr. Mohammad Vojgani Farimah Masoumi Immunology Department TUMS

The endocrine glands

absence of a duct system The endocrine glands rich vascularization

Autoimmune Endocrinopathy Adrenal Glands Autoimmune Response Pituitary Gland Thyroid Autoimmune Endocrinopathy Ovaries Pancreas Parathyroid Testes

Graves disease Hashimoto thyroiditis diabetes mellitus Autoimmune polyendocrinopathy syndrome Addison disease

Diabetes

Glucose Intolerance Hyperglycemia FBS > 126 mg/dl HbA1c > 7.5 OGTT >200 mg/dl

Signs & symptoms Hyperglycemia Polyuria Ketoacidosis Ketonuria Ketunemia Nausea Hyperventilation Weight Loss

Presence of autoantibodies Immune-mediated (Juvenile onset/IDDM) B. Idiopathic Presence of autoantibodies Type 1 (Fulminant) Diabetes Mellitus (DM) Type 2 (NIDDM) Gestational diabetes

environmental factors Stages in the development of type 1A diabetes.

Genetic susceptibility environmental factors Genetic susceptibility Active autoimmunity

environmental factors Stages in the development of type 1A diabetes.

Stages in the development of type 1A diabetes.

Stages in the development of type 1A diabetes.

Clinical manifestation Immune destruction of β cells months to years overt hyperglycemia Clinical manifestation

Clinical manifestation Immune destruction of β cells months to years overt hyperglycemia Clinical manifestation

Autoimmune Response β‑cell hormone insulin (or proinsulin) glutamic acid decarboxylase (GAD65) Islet cell autoantigen (ICA) 512 ZnT8 (zinc transporter) ICA512 (IA2) PDX1

Genetic susceptibility IDDM Environmental Factors

Genetic susceptibility HLA genes Genetic susceptibility Non-HLA genes Coxsackie B virus Infections Rubella virus Milk proteins Environmental Factors vitamin D

Non-HLA genes CTLA-4 PTPN22 CD25 CD40 Insulin Protein tyrosine phosphatase, non-receptor type 22 (lymphoid), Several modulators of T-cell signaling have been defined as important susceptibility determinants in autoimmunity.15 For example, CTLA4 polymorphisms are associated with increased risk of a variety of autoimmune diseases, including type I diabetes, Graves disease, and RA. Similarly, a functional polymorphism in PTPN22 has been identified as a major risk factor for several human autoimmune diseases, including SLE, RA, and type I diabetes. Although the exact mechanisms underlying susceptibility to autoimmunity remain unclear, in both cases the polymorphisms appear to regulate the balance of stimulatory and inhibitory signaling in effector and regulatory T cells, favoring effector T-cell activation.

ErbB3 is a member of the epidermal growth factor receptor (EGFR/ERBB).

Role of HLA genes

Genetic susceptibility HLA genes Genetic susceptibility Non-HLA genes Coxsackie B viruse Infections Rubella virus Environmental Factors Milk proteins vitamin D

coxsackie viral protein 2 C (P2-C) coxsackievirus B Molecular mimicry GAD65

Coxsackie viral protein 2 C (P2-C) Bind to HLA-DR3 Molecular mimicry GAD65

Genetic susceptibility IDDM Environmental Factors

Bystander activation

inhibit the suppressive activity of Treg viral infections TLRs inhibit the suppressive activity of Treg Auto-aggressive T cells T Reg cells

Abnormality in Treg suppressive function viral infections TLRs inhibit the suppressive activity of Treg Abnormality in Treg suppressive function T Reg cells Auto-aggressive T cells

Milk Proteins (Cow's milk ) bovine serum albumin (BSA) Molecular Mimicry BSA ICA-69

Molecular Mimicry BSA ICA-69 Oral tolerance

Role of immune cells in β-cell destruction?

β-cell proteins are phagocytosed by professional antigen-presenting cells (APCs), such as dendritic cells. APCs process these proteins to peptide fragments that are presented by MHC class II molecules to pro-inflammatory T helper 1 (TH1) cells, which in turn activate a cascade of immune responses, including activation of B cells (which produce islet antigen-specific autoantibodies) and islet antigen-specific cytotoxic T lymphocytes (CTLs) that can directly lyse β-cells presenting islet peptides by MHC class I molecules on their surface. Alternatively, APCs can present islet antigenic peptides to regulatory T (TReg) cells that suppress the pro-inflammatory cascade, preventing β-cells from being destroyed. Several immunological features (boxes) distinguish patients with type 1 diabetes from healthy individuals, collectively predisposing them to disease.

Selective destruction of pancreatic β cells

Clinical manifestation Immune destruction of β cells months to years overt hyperglycemia Clinical manifestation Diagnostic Biomarkers

Biomarker and Diagnosis ZnT8Ab autoantibody test (FDA approved)

Immunotherapy Autoantigen Therapy Monoclonal antibody therapy DCs therapy (DV-0100, phase II) Immunotherapy Treg therapy MSC Transplantation Islet cell Transplantation

? Autoantigen Therapy restore tolerance induction of regulatory T cells ? Autoantigen Therapy restore tolerance

GAD-alum vaccine (phase III) Glutamic acid decarboxylase 65 (GAD65) and DiaPep277 (a protein corresponding to amino-acid positions 437–460 of the human heat shock protein 60) are examples of antigen-specific therapies that aim to restore tolerance and achieve remission of autoimmunity in type 1 diabetes. The exact mechanism of how antigen-specific tolerance is achieved is not clear, but induction of regulatory T cells has been postulated94. Cytokine-targeted therapy with anti-tumour necrosis factor (TNF) therapy (for example, with etanercept) or anti-interleukin-1 (IL-1) therapy (for example, with anakinra) may downregulate pro-inflammatory responses that may maintain insulitis. In addition, anti-IL-1 therapy may help preserve pancreatic β-cell function. Cytotoxic T lymphocyte-associated antigen 4–immunoglobulin G1 (CTLA4–Ig; for example, abatacept) binds the CTLA4 ligands CD80 and CD86 and prevents T cell activation via co-stimulation of CD28. Normally, CTLA4 is expressed on the surface of CD4+ cells and delivers an inhibitory signal when it binds CD80 and CD86 on antigen-presenting cells (APCs). Rabbit anti-thymocyte globulin (rATG; also known as thymogobulin) is a purified polyclonal γ-immunoglobulin raised in rabbits against human thymocytes. The main mechanism of action of rATG is the depletion of T cells. Anti-CD20 therapy (for example, rituximab, a chimeric antibody that targets CD20 found on B lymphocytes) depletes B lymphocytes. For details on the mechanism of action of anti-CD3 therapies, see Fig. 3. MHC, major histocompatibility complex.

Teplizumab and otelixizumab are non-Fc receptor binding CD3-specific humanized monoclonal antibodies (mAbs) that act in a biphasic manner. Initially, there is a partial depletion of activated pathogenic T cells, and this effect is short-lived. The second durable response is postulated to involve the induction of regulatory T (TReg) cells. Interleukin-10 (IL-10)-producing and FOXP3+ CD4+ and CD8+ TReg cells have been described. The CD4+ TReg cell population is thought to act through the production of transforming growth factor-β (TGFβ) and IL-10. This induced TReg population may inhibit autoreactive T cells to pancreatic islet β-cells and thereby restore tolerance. APC, antigen-presenting cell; MHC, major histocompatibility complex.

down regulate pro-inflammatory responses Etanercept (anti-TNF) down regulate pro-inflammatory responses

Rabbit anti-thymocyte globulin (rATG

Rabbit anti-thymocyte globulin (rATG

Adoptive transfer of regulatory T cells GAD65 GAD65-specific TR 1 cells

Hashimoto thyroiditis Grave’s disease Hashimoto thyroiditis

Hashimoto’s thyroiditis Graves disease Hashimoto’s thyroiditis Autoimmune hyperthyroidism Autoimmune hypothyroidism

Autoantigens in autoimmune thyroiditis Thyroid Peroxidase (TPO) TSH-R Thyroglobulin (Tg)

Hashimoto’s thyroiditis Graves’ disease During Hashimoto’s thyroiditis, self-reactive CD4+ T lymphocytes recruit B cells and CD8+ T cells into the thyroid. Disease progression leads to the death of thyroid cells and hypothyroidism. Both autoantibodies and thyroid-specific cytotoxic T lymphocytes (CTLs) have been proposed to be responsible for autoimmune thyrocyte depletion. b | In Graves’ disease, activated CD4+ T cells induce B cells to secrete thyroid-stimulating immunoglobulins (TSI) against the thyroid-stimulating hormone receptor (TSHR), resulting in unrestrained thyroid hormone production and hyperthyroidism.

Cell-mediated immune response Hashimoto’s thyroiditis Graves’ disease Cell-mediated immune response Autoantibody Autoantibody During Hashimoto’s thyroiditis, self-reactive CD4+ T lymphocytes recruit B cells and CD8+ T cells into the thyroid. Disease progression leads to the death of thyroid cells and hypothyroidism. Both autoantibodies and thyroid-specific cytotoxic T lymphocytes (CTLs) have been proposed to be responsible for autoimmune thyrocyte depletion. b | In Graves’ disease, activated CD4+ T cells induce B cells to secrete thyroid-stimulating immunoglobulins (TSI) against the thyroid-stimulating hormone receptor (TSHR), resulting in unrestrained thyroid hormone production and hyperthyroidism. Blocking anti-TSHR Activator anti-TSHR

Lymphocyte infiltration ectopic follicle (germinal center) Hashimoto’s thyroiditis

Main histopathological feature Hashimoto’s thyroiditis massive lymphocyte accumulation

Transient Graves’ disease Antibody-mediated autoimmune diseases can appear in the infants of affected mothers as a consequence of transplacental antibody transfer. In pregnant women, lgG antibodies cross the placenta and accumulate in the fetus before birth (see Fig. 1 0.24). Babies born to mothers with lgG-mediated autoimmune disease therefore frequently show symptoms similar to those of the mother in the first few weeks of life. Fortunately, there is little lasting damage because the symptoms disappear along with the maternal antibody. In Graves' disease, the symptoms are caused by antibodies against the thyroidstimulating hormone receptor (TSHR). Children of mothers making thyroid-stimulating antibody are born with hyperthyroidism, but this can be corrected by replacing the plasma with normal plasma (plasmapheresis), thus removing the maternal antibody.

Graves’ ophthalmopathy Orbit Fibroblast

Graves’ ophthalmopathy Orbit Fibroblast hyaluronic acid secrete cytokines and chemokines adipogenesis Inflammatory response restriction of extraocular eye movements edema and swelling

optic-nerve compression

following surgical orbital decompression and rehabilitative surgery

Environmental factors Smoking Iodine Stress Successful treatment of HIV with HAART (highly active antiretroviral therapy) Infections e.g., hepatitis C

Autoimmune polyendocrine syndromes Autoimmune polyendocrine syndrome type I (APS-I) Autoimmune polyendocrine syndrome type II (APS-II) IPEX Autoimmune polyendocrine syndrome type I (APS1), also called autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED), is a rare disease in which patients develop multiple autoimmune diseases, often beginning in childhood.7 While candidiasis and ectodermal dystrophy (including involvement of enamel and nails, as well as keratopathy) are features of the disease, the syndrome is characterized by striking autoimmunity directed against multiple different target tissues. Autoimmune processes include autoimmune hypoparathyroidism, Addison disease, autoimmune gastritis with pernicious anemia, type I diabetes, thyroid disease, autoimmune hepatitis, celiac disease, and gonadal failure. The genetic basis of APS1 was mapped to a gene on chromosome 21q22.3, subsequently termed AIRE (for autoimmune regulator). AIRE expression is highest in the thymus, where it is expressed in medullary thymic epithelial cells. Several predicted structural features of the AIRE protein, and its localization in nuclear dots, suggested that the protein might be a transcriptional regulator, and significant evidence for this proposal was obtained in vitro. Several AIRE-deficient mouse models were subsequently generated, which allowed the definition of important pathogenic pathways in APS1 that are likely broadly relevant to the mechanisms of autoimmunity in general. Thus, mice deficient for AIRE developed various autoimmune phenotypes, resembling those found in human APS1. These included multiorgan lymphocytic infiltration and autoantibodies, as well as autoimmune eye disease. In an elegant series of experiments, Mathis and colleagues demonstrated that AIRE regulates expression in thymic epithelial cells of various peripheral autoantigens normally expressed exclusively in endocrine target tissues. 9 Similarly, thymic expression of the mouse lung protein vomeromodulin is also AIRE-dependent, and loss of tolerance to this antigen is sufficient to cause interstitial lung disease in wild type mice.10 Thus, AIRE appears to regulate the ectopic expression in the thymus of tissue-restricted autoantigens, and provide an antigen source against which to establish central tolerance.

Abbreviations: APS, autoimmune polyglandular syndrome; CTLA4, cytotoxic T lymphocyte associated antigen 4; FOXP3, forkhead box P3 gene; GAD, glutamate decarboxylase; HLA, human leukocyte antigen; IPEX, immune dysfunction, polyendocrinopathy, enteropathy, X‑linked; MICA5.1, MHC class I‑related gene A; IA‑2, islet antigen 2; PTPN22, protein tyrosine phosphatase, non‑receptor 22; TPO, thyroid peroxidase; Tg, thyroglobulin; TTG, tissue transglutaminase; VNTR, variable number tandem repeat in the 5' promoter of the insulin gene; ZnT8, zinc T8 transporter.

Pathogenic model for the autoimmune polyglandular syndromes HLA-II molecules predispose to tissue specific targeting

Autoimmune polyendocrine syndrome type I (APS-I) autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) manifests during infancy a child has at least two of the following pathologies: 1) mucocutaneous candidiasis 2) Hypoparathyroidism (hypocalcemia) 3) Addison disease (Hypotension or fatigue) Eighteen percent of patients develop type 1A diabetes

transcription factor AIRE (autoimmune regulator) Central Tolerance

APS-2 presence of at least two of three diseases in the same patient: T1DM Addison disease and autoimmune thyroid disease

APS-2 Schmidt syndrome the most frequent autoimmune polyglandular syndrome the incidence is two to three times higher in females than in males

Autoantibodies in APS2: anti‑21OH in Addison disease Anti-glutamic acid decarboxylase in T1DM Anti-IA‑2 in T1DM

Autoimmune Addison disease primary adrenocortical insufficiency (autoimmune disease) Individuals with type 1A diabetes have a 100 times greater risk of developing Addison’s disease This significant increase justifies anti-21-hydroxylase autoantibody screening in type 1A diabetics.

Steroidogenic enzymes Adrenal Glands steroid 21-hydroxylase (CYP21) Cortisol Aldosterone Steroidogenic enzymes steroid 17‑α-hydroxylase

Stages in the development of Addison disease Stages in the development of Addison disease. Adrenocortical function is lost over a period of years. In the first stage, genetic predisposition is conferred through human leukocyte antigen (HLA) genes. In the second stage, unknown events precipitate anti‑adrenal autoimmunity. In the third stage, which involves presymptomatic disease, steroid 21‑hydroxylase autoantibodies production predicts future disease. Finally, overt Addison disease develops. An increased plasma renin level is one of the first metabolic abnormalities to occur and is followed by the sequential development of other metabolic abnormalities (a decreased cortisol level after cosyntropin stimulation, an elevated ACTH level and a decreased basal cortisol level). Finally, symptoms of adrenal insufficiency, such as fatigue, hyperpigmentation and hypotension, manifest. Abbreviations: ACTH, adrenocorticotropic hormone. Stages in the development of Addison disease

IPEX syndrome immunodysregulation polyendocrinopathy enteropathy X-linked syndrome Extremely rare disease mutations in the forkhead box P3 (FOXP3) gene results in the absence or dysfunction of regulatory T cells Main manifestation: type 1A diabetes mellitus that can develop as early as 2 days after birth Children affected with IPEX syndrome usually die in the first 2 years of life

An overview of the common, less common and rare autoimmune and/or endocrine diseases and their affected organs that are discussed in this article. Abbreviations: AIT, autoimmune thyroid disease; APS2, autoimmune polyendocrine syndrome type 2; APS1, autoimmune polyendocrine syndrome type 1; IPEX, immune dysfunction, polyendocrinopathy and enteropathy, X‑linked; SLE, systemic lupus erythematosus; T1DM, type 1 diabetes mellitus.

Case Billy was born at full term and developed atopic dermatitis shortly after birth. local application of hydrocortisone and antihistamines to control itching, the treatment being only partly successful. At 4 months of age, Billy developed an intractable watery diarrhea his weight had fallen below the third centile for his age. At 6 months old, Billy started to develop high blood glucose levels and glucose in the urine Eczematous rash on the face He was diagnosed with type 1 diabetes

His cervical and axillary lymph nodes and spleen were enlarged Laboratory tests revealed a normal white blood cell count Autoantibodies were found against glutamic acid decarboxylase (the GAD65 antigen) and against pancreatic islet cells. a duodenal biopsy revealed almost total villous atrophy-an absence of villi in the lining of the duodenum-with a dense infiltrate of plasma cells and T cells An endoscopy was ordered, to ascertain the cause of his persistent diarrhea, and When Billy's mother was questioned, she revealed that there had been another son, who had died in infancy with severe diarrhea and a low platelet count.

On the basis of Billy's symptoms and the family history, IPEX (immune dysregulation, polyendocrinopathy, enteropathy X-linked) was suspected A FACS analysis of Billy's peripheral blood mononuclear cells revealed a lack of both CD4 CD25 cells and CD4 Foxp3-positive cells. Sequencing of Billy's FOXP3 gene revealed a missense mutation, confirming the diagnosis.

With the diagnosis established, immunosuppressive therapy, including cyclosporine and tacrolimus, was started After several months, however, his symptoms began to return and he stopped gaining weight. Shortly afterwards, he developed thrombocytopenia (a deficiency of blood platelets) and anti-platelet antibodies were detected. The decision was made for Billy to be given a bone marrow transplant from his 5-yearold HLA-identical sister.

 Case 15.1 Graves' disease A 29-year-old woman presented with a 3-month history of increased sweating and palpitations with weight loss of 7kg. On examination, she was a nervous, agitated woman with an obvious, diffuse, non-tender, smooth enlargement of her thyroid, over which a bruit could be heard. She had a fine tremor of her fingers and a resting pulse rate of 150/minute. She had no evidence of exophthalmos (contrast with figure which shows exophthalmos). A maternal aunt had suffered from 'thyroid disease'. On investigation, she had a raised serum T3 of 4.8nmol/l (NR 0.8-2.4) and a T4 of 48nmol/l (NR 9-23). Measurement of her thyroid-stimulating hormone showed that this was low normal, 0.4mU/l (NR 0.4-5_mU/l). The biochemical findings pointed to primary thyroid disease rather than pituitary overactivity. Circulating antibodies to thyroid peroxidase (titre 1/3000; 200iu/ml) were detected by agglutination. A diagnosis of autoimmune thyrotoxicosis (Graves' disease) was made. She was treated with an antithyroid drug, carbimazole, to control her thyrotoxicosis, and surgery was not required.