Disorder of immune system Yeong-Wook Song, MD Division of Rheumatology Seoul National University

2 Objectives 1Define the terms infection, pathogen, and antigen, tolerance, autoimmunity, rheumatic disease. 2List and describe mechanism of the nonspecific and specific body defense mechanisms. 3Explain the signs and causes of inflammation.  Define B cells and T cells and describe their locations and functions.  Explain the importance of MHC proteins. The Immune System

3 Objectives (cont.) 6List the different types of T cells and describe their functions. 7List the different types of antibodies and explain how they differ and how they fight infection.  Define complement and give its functions.  Explain the difference between innate and adaptive immunity.  Describe the signs and symptoms of common immune disorders (rheumatoid arthritis, lupus, ankylosing spondylitis scleroderma, myositis). The Immune System

4 What does the immune system do? Normal (physiologic) functions: – Immunity = protection against infection – Defense against some tumors Roles in disease: – Cause of many immunological diseases (allergies, autoimmune diseases) – Suspected role in many diseases thought to be non-immune (atherosclerosis, Alzheimer’s disease, type 2 diabetes)

5 Innate immunity: always present (ready to attack); many pathogenic microbes have evolved to resist innate immunity Adaptive immunity: stimulated by exposure to microbe; more potent Innate and adaptive immunity Abbas, Lichtman and Pillai. Cellular and Molecular Immunology, 7 th edition, 2011 c Elsevier

6 Cells of the immune system Lymphocytes: the cells of adaptive immunity; recognize antigens and develop (differentiate) into cells that perform the defense functions Antigen-presenting cells: cells that capture antigens and display them to lymphocytes Effector cells: leukocytes (white blood cells) that eliminate microbes (the “effect” of the immune response); may be lymphocytes, but are often other leukocytes

7 Classes of lymphocytes Excluding NK cells and other innate lymphoid cells Abbas, Lichtman and Pillai. Cellular and Molecular Immunology, 7 th edition, 2011 c Elsevier

Lymphocytes with highly specific and diverse antigen receptors develop prior to exposure to antigens Lymphocyte diversity and clonal selection Generation of mature lymphocytes with many different antigen receptors Naïve lymphocytes circulate through lymphoid organs Specific lymphocytes recognize antigens Lymphocytes are activated to proliferate and to differentiate into effector cells Lymphocyte precursor Antigen X Antigen Y Anti-Y antibody Anti-X antibody

9 Adaptive immune responses

Stages in the life history of lymphocytes Proliferation: expands number of antigen-specific cells Differentiation: converts lymphocytes into effective defenders

The immune system can cause disease Excessive, uncontrolled responses against infectious pathogens (collateral damage) Inappropriate responses against self antigens may cause injury to normal tissues, resulting in disease Fundamental defect is failure of control mechanisms in the immune system

The significance of recent advances Provides a solid foundation of basic principles Improved understanding of disease mechanisms Development of novel therapies Appreciation of the role of the immune system in non-immune diseases

13 Inflammation Signs:  Redness  Heat  Swelling  Pain Signs:  Redness  Heat  Swelling  Pain Causes:  Injured or infected with a pathogen, inflammation can resultCauses:

14 Major Immune System Disorders Diseases and disorders that challenge the immune system: (the following are the most significant)  HIV/AIDS  Infections  Autoimmune disease  Cancer  Allergies

15 Acquired Immune Deficiency Syndrome (AIDS) Caused by human immunodeficiency virus (HIV) infection Most common routes of transmission are through sexual contact, blood, or from mother to child during pregnancy or breast-feeding. Caused by human immunodeficiency virus (HIV) infection Most common routes of transmission are through sexual contact, blood, or from mother to child during pregnancy or breast-feeding. Can have infection for years before developing any symptoms of this disease Less common routes of transmission are through accidental needle sticks, artificial insemination, and organ transplants.

16 Acquired Immune Deficiency Syndrome (AIDS) (cont.)  AIDS virus affects the immune system  Counts of CD4 cells are used to diagnose the stage of HIV infection. If below 200 patient has AIDS  AIDS virus affects the immune system  Counts of CD4 cells are used to diagnose the stage of HIV infection. If below 200 patient has AIDS  CD4 cells are types of T cells and are important for the functions of other components of the immune system.

17 Acquired Immune Deficiency Syndrome (AIDS) (cont.) Signs and Symptoms of AIDS:  Low T cell counts  Fever  Profuse sweating  Weakness  Weight loss  Swollen glands  Frequent infections  Some rare forms of cancer  A common form of cancer is called “Kaposi’s” sarcoma.

18 Allergies Allergies Allergic reaction is an immune response to a substance Allergens - trigger of allergic responses Allergic reaction is an immune response to a substance Allergens - trigger of allergic responses Anaphylaxis - blood vessels dilate quickly causing blood pressure to drop too quickly for organs to adjust. This condition is life threatening.

19 Allergies (cont.) Allergies (cont.) Allergic reactions involve IgE antibodies and mast cells. IgE antibodies bind to allergens, they cause mast cells to release histamine and heparin These chemicals trigger allergic reactions. If a person is receiving allergy shots, he is being injected with tiny amounts of the allergen and reduces symptoms

Immunology in Rheumatic Diseases

Toll like receptors (TLRs)

Value of the Immune System Macrophages & toll-like receptors (TLRs) different TLRs can (collectively) bind a wide range of pathogens Each macrophage has all of the set of TLRs

TLRs and Autoimmunity Clear evidence they play a role in SLE and RA Clear evidence they play a role in SLE and RA Clear evidence that intrinsic molecules trigger TLRs in RA and SLE Clear evidence that intrinsic molecules trigger TLRs in RA and SLE Targeted inhibitors of TLRs are in Phase II trials Targeted inhibitors of TLRs are in Phase II trials Agonists of TLRs are being used as vaccine and tumor adjuvants Agonists of TLRs are being used as vaccine and tumor adjuvants

Antigen Presenting Cells Unlike the other cells, T H cells only recognize antigen that is properly presented with MHC by other cells Unlike the other cells, T H cells only recognize antigen that is properly presented with MHC by other cells These specialized cells are called antigen presenting cells These specialized cells are called antigen presenting cells They include macrophages, B cells, fibroblasts & dendritic cells They include macrophages, B cells, fibroblasts & dendritic cells

Major Histocompatibility Complex (MHC) Antigen is ingested by the antigen presenting cell then presented on its surface in molecules called major histocompatibility complex Antigen is ingested by the antigen presenting cell then presented on its surface in molecules called major histocompatibility complex MHC are also the molecules responsible for rejection in transplant organs MHC are also the molecules responsible for rejection in transplant organs

Major Histocompatibility Complex MHC proteins =HLA(Human Leucocyte Antigen) in MHC proteins =HLA(Human Leucocyte Antigen) inhumans Molecules on cell surfaces which can display antigen Molecules on cell surfaces which can display antigen Products of a region of highly polymorphogenic genes on chromosome 6 Products of a region of highly polymorphogenic genes on chromosome 6 2 types : 2 types : Class I & Class I & Class II Class II

Comparison of MHC Class I & II Molecules Comparison of MHC Class I & II Molecules Class I Class II Genes HLA A/B/C HLA D Expressed on All nucleated cells APCs – B cells, macrophages & dendritic cells Size 9 to 10 amino acids (smaller) 12 to 28 amino acids (larger) Source of antigen displayed Intracellular eg viral infections Extracellular eg bacterial infections Antigen presented to CD8+ T cells CD4+ cells ( APC = Antigen presenting cell)

Activation of the Adaptive Immune System Antigens that escape the innate immune system encounter the adaptive system Antigens that escape the innate immune system encounter the adaptive system Adaptive immune system – powerful  must be activated Adaptive immune system – powerful  must be activated

Activation of the Adaptive Immune System 1.APC eg Macrophage ingests Ag 2. Ag presented on cell surface with MHC 3. T cell recognizes its cognate Ag 4. 2 nd signal required = protein on APC + a T H cell receptor 5. ACTIVATION & 6. Cytokine production In this diagram, the macrophage represents the innate system & the T H cell, the adaptive system

Cytokines Cells of the immune system communicate with each other using cytokines Cells of the immune system communicate with each other using cytokines Protein hormones Protein hormones Mediate the effect of the innate & Mediate the effect of the innate & specific immunity specific immunity Autocrine/ paracrine/endocrine Autocrine/ paracrine/endocrine Effects include cell activation, division, apoptosis, movement Effects include cell activation, division, apoptosis, movement

Cytokine types Interleukins – Interleukins – – produced by leucocytes & have effects mainly on WBC Chemokines – Chemokines – – chemoattractants Colony stimulating factors – Colony stimulating factors – – differentiation & proliferation of stem cells Interferons – Interferons – – interfere with viral replication Eg. Eg. Il-2 = a growth factor that stimulates CTLs & NK cells to proliferate TNF activates primed macrophages & NK cells TNF activates primed macrophages & NK cells

Cells & cytokine production Cells Cytokines Antigen IL2 T H 1IFN  Viruses (CD4) TNF Bacteria TH0 IL 4 T H 2IL 5 Parasites (CD4)IL10 Cells produce different subgroups of cytokines which will instruct the innate & adaptive systems to produce cells & antibodies against specific antigens. Here is an example

T Cell Subsets – the Family Grows

Naive CM EM TEM Naïve (CD45RA+CCR7+) CM: central memory (CD45RA-CCR7+) EM: effector memory (CD45RA-CCR7-) TEM: terminal effector memory (CD45RA+CCR7-)

IL-12 IL-23 p40 p35 IL-12R β1 IL-12R β2 IL-23R Signal p19 Th1 cell proliferationTh17 cell proliferation INF IL-6 IL-1 IL-22 NK or T cell membrane

2. Tolerance Is ……………. the immunologic unresponsiveness to self antigens the immunologic unresponsiveness to self antigens It allows the immune system to protect the body without turning against itself It allows the immune system to protect the body without turning against itself The focus is on the adaptive immune system The focus is on the adaptive immune system T & B cells must be able to discriminate self from non self T & B cells must be able to discriminate self from non self This occurs centrally & peripherally This occurs centrally & peripherally

Central T Cell Tolerance T cells are produced in the bone marrow & migrate to the thymus. T cells are produced in the bone marrow & migrate to the thymus. Here they go through a rigorous selections Here they go through a rigorous selections process. process. Only T cells that react to antigen but not self exit. Only T cells that react to antigen but not self exit. The rest die by apoptosis. The rest die by apoptosis. NEJM 2001;344(9): 655 – 664.

Peripheral T Cell Tolerance If autoreactive T cells enter the circulation, there are several mechanisms that can prevent an autoimmune reaction. NEJM 2001;344(9): 655 – 664.

B Cell Tolerance CENTRAL CENTRAL –Clonal deletion of autoreactive B cells in the bone marrow, spleen & lymph nodes. PERIPHERAL PERIPHERAL –Lack of help from T cells is the predominant factor.

Breakdown in peripheral tolerance

3. Autoimmunity Breakdown in mechanisms preserving tolerance to self Breakdown in mechanisms preserving tolerance to self Severe enough to cause a pathological condition Severe enough to cause a pathological condition

Autoimmune diseases Organ specific e.g. Organ specific e.g. –Insulin dependant diabetes –Myasthenia gravis Multisystem e.g. Multisystem e.g. –Rheumatoid arthritis –SLE

Mechanisms GENETIC FACTORS Aberant MHC/HLA - present self peptide Autoreactive T & B cells ENVIRONMENTAL FACTORS Infectious/ noninfectious triggers Hypothesis : Molecular mimicry Molecular mimicry : The antigen looks similar to a self-peptide. As a result, the body produces an immune response to the trigger factor as well as to self. AUTOIMMUNE DISEASE

The Major Theories in the Development of Autoimmune Diseases Release of the normally sequestered antigens Release of the normally sequestered antigens Increased expression of autoantigen/cryptic epitope/MHC II Increased expression of autoantigen/cryptic epitope/MHC II Molecular mimicry, Epitope spreading Molecular mimicry, Epitope spreading Defects in apoptosis Defects in apoptosis Decreased cell numbers or function of suppressor and/or regulatory cells Decreased cell numbers or function of suppressor and/or regulatory cells Altered Th1 and Th2 cytokine pattern Altered Th1 and Th2 cytokine pattern Increased expression of costimulatory molecules Increased expression of costimulatory molecules Release of inflammatory mediators Release of inflammatory mediators

Autoantibodies in Connective Tissue Diseases Produced by B cells Produced by B cells May be pathogenic eg. May be pathogenic eg. –Form immune complexes in lupus nephritis Markers of certain diseases Markers of certain diseases May not be diagnostic May not be diagnostic –Apart from rheumatic disorders, they may be found in normal population & with other conditions –Therefore only test when clinically indicated.

Autoantibodies associated with disease Autoantibodies associated with disease DISEASEAUTOANTIBODY Rheumatoid Arthritis Rheumatoid factor SLE ANA,dsDNA, Smith SclerodermaANA,centromere,topoisomerase AntiphospholipidSyndrome Anticardiolipin (ACLA) Sjogren ’ s syndrome Ro, La PolymyositisJo-1 DermatomyositisMi-2 Wegener ’ s granulomatosis c-ANCA

Cellular Targets for autoantibodies Ab to intracellular proteins -proteinase 3 cANCA Ab to cell membrane Proteins ACLA Antinuclear antibodies (ANA) dsDNA ENA – Smith, Ro, La, RNP Centromere, topoisomerase Ribosomal & lysosomal components -t RNA synthetase AntiJo 1 Ab to IgG Rheumatoid factor This diagram depicts the autoantibodies & their respective target antigens

1. Immune Mechanisms 2. Tolerance 3. Autoimmunity 4. Rheumatologic conditions –Rheumatoid arthritis –Systemic Lupus Erythematosis –Spondarthropathies –Inflammatory myopathies –Systemic sclerosis The above disease will be used to highlight some of the concepts of Immunology in Rheumatology. Note that the details of each pathway does NOT have to be memorized.

Rheumatoid Arthritis Chronic autoimmune disorder Chronic autoimmune disorder Affects 1% of population Affects 1% of population A symmetrical peripheral polyarthritis of unknown etiology that leads to joint deformity & destruction due to erosion of cartilage & bone

Inflammation Drives Arthritis The inflammatory process results in damage to cartilage & bone NEJM 2001; 344 (12): 907 – 916.

Rheumatoid Factor Rheumatoid Factor is an autoantibody produced in RA Rheumatoid Factor is an autoantibody produced in RA It is however produced in several other conditions It is however produced in several other conditions  Clinical features are important in making the diagnosis  Clinical features are important in making the diagnosis Anti-CCP Ab Anti-CCP Ab

Rheumatoid Arthritis Current therapies Current therapies –Nonsteroidal anti-inflammatory drugs (NSAIDs) –Oral corticosteroids –Disease-modifying antirheumatic drugs (DMARDs) D-penicillamine, auranofin, hydroxychloroquine, azathioprine, MTX D-penicillamine, auranofin, hydroxychloroquine, azathioprine, MTX MTX has the most rapid onset of action and is well tolerated with long-term use MTX has the most rapid onset of action and is well tolerated with long-term use Many patients receiving DMARD therapy show only partial symptom relief and still exhibit features of active disease Many patients receiving DMARD therapy show only partial symptom relief and still exhibit features of active disease

New Agents for the Treatment of RA New Agents for the Treatment of RA Cytokine inhibitors Cytokine inhibitors –Human monoclonal Ab to TNFα –PEGylated anti-TNFα –Monoclonal antibody to IL-6 receptor –JAK3 inhibition Co-stimulatory molecule blockers-abatacept Co-stimulatory molecule blockers-abatacept Targeted B-cell therapy- anti-CD20 Targeted B-cell therapy- anti-CD20 yOther unique mechanisms of action yOther unique mechanisms of action

Systemic Lupus Erythematosus Signs:  Arthritis  “Butterfly” rash on face  Sensitivity to sunlight  Renal failure  Headaches  Mental disorders A generalized connective tissue disorder affecting many organs and characterized by the production of many autoantibodies

Systemic lupus erythematosus classification criteria (SOAP BRAIN MD) S 1. Serositis: (a) pleuritis, or (b) pericarditis O 2. Oral ulcers A 3. Arthritis P 4. Photosensitivity M 10. Malar rash D 11. Discoid rash B 5. Blood/Hematologic disorder: (a) hemolytic anemia or (b) leukopenia of < 4.0 x 10 9 (c) lymphopenia of < 1.5 x 10 9 (d) thrombocytopenia < 100 X 10 9 R 6. Renal disorder: (a) proteinuria > 0.5 gm/24 h or 3+ dipstick or (b) cellular casts A 7. Antinuclear antibody (positive ANA) I 8. Immunologic disorders: (a) raised anti-native DNA antibody binding or (b) anti-Sm antibody or (c) positive anti-phospholipid antibody work-up N 9. Neurological disorder: (a) seizures or (b) psychosis "...A person shall be said to have SLE if four or more of the 11 criteria are present, serially or simultaneously, during any interval of observation."

Lupus Nephritis The kidney biopsy on the right is from a patient with diffuse proliferative lupus nephritis shows massive deposits of IgG on immunofluorescence The kidney biopsy on the right is from a patient with diffuse proliferative lupus nephritis shows massive deposits of IgG on immunofluorescence

Ankylosing Spondylitis AS is a chronic inflammatory disease of the axial skeleton manifested by back pain & progressive stiffness of the spine

Ankylosing Spondylitis The prevalence of the MHC,HLA-B27 is high in The prevalence of the MHC,HLA-B27 is high in Caucasians Caucasians but rare in Black but rare in Black populations with Ankylosing Spondylitis populations with Ankylosing Spondylitis

Dermatomyositis Dermatomyositis An idiopathic inflammatory myopathy associated with certain characteristic cutaneous manifestations

Note: the inflammatory infiltrate in the muscle biopsy of this patient with Dermatomyositis

Scleroderma The term encompasses a heterogeneous group of conditions linked by the presence of thickened sclerotic skin lesions

The inflammatory process in Scleroderma results a marked fibrotic precess responsible for many of the clinical features

Scleroderma Lung Disease 2 important lung diseases which occur due to the inflammatory process in Scleroderma

86 Summary Summary Medical Assistant Knowledge of the immune system forms the basis of understanding many of the diseases and disorders of the immune system and has become the focus of many exciting new treatment strategies. You must have knowledge of this system when assisting the physician during the examination of a patient who is having problems with their immune system.

87 Apply Your Knowledge Apply Your Knowledge Your 18-year-old patient states that he thinks his right big toe is inflamed. What symptoms would you expect to see?

88 Apply Your Knowledge - Answer Apply Your Knowledge - Answer Redness, heat, swelling, and pain Your 18-year-old patient states that he thinks his right big toe is inflamed. What symptoms would you expect to see?

89 Apply Your Knowledge Apply Your Knowledge How can a patient contract HIV?

90 Apply Your Knowledge - Answer Most common routes of transmission are through sexual contact, blood, or from mother to child during pregnancy or breast-feeding How can a patient contract HIV?

91 Apply Your Knowledge Apply Your Knowledge As you are taking your patient to the exam room, you notice that she has “Butterfly” rash on her face. What disorder exhibits this sign?

92 Apply Your Knowledge - Answer Lupus As you are taking your patient to the exam room, you notice that she has “Butterfly” rash on her face. What disorder exhibits this sign?

References  Sompayrac L. How the Immune System works. Blackwell Science, Inc  Roitt IM. Roitt’s Essential Immunology 10 th ed. Blackwell Science 2001  Hochburg et al. Rheumatology 3 rd ed. Mosby 2003  UpToDate 12.3  Kalla AA. Rheumatology Handbook. Rheumatic Diseases Unit Univrersity of Cape Town. 2003

References (cont)  Parkin J, Cohen B. An overview of the immune system. Lancet 2001;357:  Mackay IR, Rosen FS. Tolerance and Autoimmunity. NEJM 2001;344(9): 655 – 664.  Mackay IR, Rosen FS. Autoimmune diseases. NEJM 2001; 345(5):  Epstein FH. Cytokine pathway and Joint Inflammation in Rheumatoid Arthritis. NEJM 2001; 344 (12): 907 – 916.  Yuan G et al. Immunologic Intervention in the Pathogenesis of Osteoarthritis. Arthritis & Rheumatism 2003; 48(3)

감사합니다

96 Introduction Immune system - protects the body against  Bacteria  Viruses  Fungi  Toxins  Parasites  Cancer

97 Defenses Against Disease Nonspecific defenses - mechanisms to protect us against pathogens in general Nonspecific Defenses  Species Resistance  Mechanical Barriers  Chemical Barriers  Fever  Inflammation  Phagocytosis

98 Specific Defenses Against Disease  Specific defenses are called immunities and protect the body against very specific pathogens  Lymphocytes and macrophages are the major white blood cells involved in specific defenses.  Antibodies and complement are the major proteins involved in specific defenses

Immunity Can Be Divided Into 2 Main Components: 1.Innate immunity Rapid acting, nonspecificRapid acting, nonspecific 2.Specific or adaptive immunity Slower onset of actionSlower onset of action Targets pathogens that escape the innate immune systemTargets pathogens that escape the innate immune system Activated by the innate immune systemActivated by the innate immune system

Physical barrier Complement Innate NK cells Phagocytic cells - neutrophils - macrophages IMMUNITY IMMUNITY Eosinophils Mast Cells Humoral ( B cells) Specific CMI ( T cells)

101 B Cells & T Cells B Cells & T Cells Two major types of lymphocytes B Cells and T Cells Recognize antigens in the body T Cells Cell-mediated bind to antigens on cells and attack them directly T Cells Cell-mediated bind to antigens on cells and attack them directly B cells Respond to antigens by becoming plasma cell - make antibodies against the specific antigen B cells Respond to antigens by becoming plasma cell - make antibodies against the specific antigen

102 T Cells T Cells Helper T cells  increase antibody formation, memory cell formation, B cell formation, and phagocytosis Memory T cells  memory cells “remember” the pathogen that activated the original T cell  person is later exposed to the same pathogen, memory cells trigger an immune response that is more effective than the first immune response Helper T cells  increase antibody formation, memory cell formation, B cell formation, and phagocytosis Memory T cells  memory cells “remember” the pathogen that activated the original T cell  person is later exposed to the same pathogen, memory cells trigger an immune response that is more effective than the first immune response

103 Antibodies Antibodies  IgG - recognizes bacteria, viruses, and toxins. It can also activate complement.  IgA - found in secretions of the body such as breast milk, sweat, tears, saliva, and mucus- prevents pathogens from entering the body.  IgM - very large - primarily binds to antigens on food, bacteria, or incompatible blood cells- activates complement.  IgE - found wherever IgA is located- involved in triggering allergic reactions.