front 1 what characteristics define mucosal tissue? | back 1 mucus-secreting epithelium joined by tight junctions communicates with external environment the site of entry for most pathogens includes linings of GI, respiratory, and urogenital tracts, mammary glands, and conjunctiva of the eye site of secretion of secretory IgA |
front 2 what are mucins? | back 2 a family of large (10,000 AA) glycoproteins secreted by mucosal epithelium size forces the glycoprotein into an extended conformation heavily hydrated various genes code for mucins that each have differences in viscoelastic properties |
front 3 what is mucus? | back 3 slimy, protective secretions composed of glycoproteins, proteoglycans, peptides, and enzymes secreted by goblet cells embedded in internal epithelium; prevents smog/smoke |
front 4 what are glycoprotein? | back 4 glycol (sugar) + proteins; rich in theronine and serine |
front 5 what are commensal microorganisms? | back 5 the digestive tract is approximately 9 meters in length, with each area having its specific function the GI tract is populated by approximately 750 species of bacteria |
front 6 what are five of the symbiotic benefits of the microbiome? | back 6 synthesis of essential metabolites breakdown of plant fibers into digestible food inactive toxic substances in food or from pathogens prevent access of pathogens to the human gut interact with epithelium to trigger development of secondary lymphoid tissue |
front 7 what are examples of secondary lymphoid tissues at mucosal sites? | back 7 GUT-associated lymphoid tissue; the most extensive secondary lymphoid tissues in the body; they key antigen sampling and adaptive immune inductive sites within the intestinal wall |
front 8 GALT consists of... | back 8 peyer's patches in the ileum appendix isolated lymphoid follicles tonsils, adenoids |
front 9 what is the inductive compartment? | back 9 directly beneath the mucosal epithelium where interactions between the antigen, dendritic cells, and lymphocytes induce adaptive immune responses |
front 10 three steps in the inductive compartment? | back 10 antigen is captured by dendritic cells or M cells and lymphocytes are activated mucosal cells produce retionic acid which - along with other cytokines- drives differentiation and homing change in homing phenotype ` |
front 11 what is the effector compartment? | back 11 connective tissue; lamina propria the residence of effector cells: plasma cells, effector T cells, macrophages, mast cells, eosinophils |
front 12 what is systemic immunity? | back 12 immunity that occurs at non-mucosal tissues interactions with microbes are relatively rare cells are recruited from the blood; DCs migrate to secondary lymphoid tissue short violent episodes of localized and intense inflammation are the price paid to squash the sporadic infections of non-mucosal tissues |
front 13 what is mucosal immunity? | back 13 immunity that occurs at mucosal tissues interactions with microbes are close and continual commensal microorganisms have a symbiotic relationship with their host but can turn pathogenic with any significant breach of the gut |
front 14 two strategies for avoiding peritonitis | back 14 the mucosal response is proactive, constantly making adaptive response against gut microbiota so healthy gut issue already has effector T and B cells ready and available the mucosal response is sparing in its use of inflammation |
front 15 what is Crohn's disease? | back 15 a chronic inflammatory bowl disease that causes inflammation anywhere in the digestive tract, most commonly in the lower part of the small intestine and the beginning of the large intestine |
front 16 how does the innate immune response in the gut work? | back 16 intestinal epithelial cells express pattern recognition receptors activation of the two receptor types thus epithelial cells have a quick and localized inflammatory response that is a sufficient to respond to the infection but not create lasting damage |
front 17 activation of the two receptor types in the gut innate immune response lead to | back 17 formation of the NLRP3 inflammasome leads to expression of NFkB production of antimicrobial peptides productions of cytokines and chemokines |
front 18 what role do intestinal macrophages play? | back 18 crucial for maintaining gut homeostasis by tolerating beneficial bacteria while still defending against pathogens. they are structurally and functionally different from blood monocytes due to their origin and lack of certain receptors, which makes them less inflammatory and prevents them from becoming professional antigen-presenting cells |
front 19 what is the role of NFkB? | back 19 functions as a transcription factor to control the expression of genes involved in the immune response, inflammation, cell growth, and survival |
front 20 what is the role TFGB? | back 20 promoting cell proliferation, differentiation, and apoptosis, as well as regulating the immune system by influencing both T and innate immune cells |
front 21 what are the cell types of the intestinal epithelium? | back 21 enterocytes goblet cells paneth cells M cells lymphoid follicle follicle-associated epithelium |
front 22 what are enterocytes? | back 22 specialized for the absorption of nutrients |
front 23 what are goblet cells? | back 23 secrete mucus |
front 24 what are paneth cells? | back 24 secretion of anti-microbial peptides and proteins |
front 25 what are M cells? | back 25 important in 'antigen sampling' take up antigen and transport them across the epithelial barrier |
front 26 what are lymphoid follicle? | back 26 a discrete, organized structure within secondary lymphoid tissue; similar to follicles discussed in the lymph node |
front 27 what are follicle-associated epithelium? | back 27 epithelium that overlies follicles |
front 28 what is the role of microfold cells? | back 28 follicle-associated epithelium overlying lymphoid tissue in the small intestine and is poorly defended microorganisms are funneled towards microfold or M cells that are strategically positioned above the lymphoid follicles |
front 29 M cells are named because... | back 29 they contain fewer folds than adjacent enterocytes; basolateral side is known as the interepithelial pocket |
front 30 what is oral tolerarnce? | back 30 if you eat something first then you are less likely to be allergic to it than if you experience it on your skin first |
front 31 what types of T cells do CD103+ DCs present to? | back 31 T(FH) and T(REG) cells |
front 32 when T(FH) and T(REG) activate B cell, what antibody isotypes do they produce? | back 32 IgM --> IgA |
front 33 how do CD103+ DCs function in the presence infection? | back 33 think escalation DCs become more mobile and can capture antigen in the absence of M cells by having extended processes through perpetual sampling T cells specific for pathogens, commensal microorganisms and food antigens are stimulated to become effector cells; T cells then activate IgA |
front 34 how do CD103+ DCs function in the absence of infection? | back 34 think surveillance in the gut, food antigens are taken up by CD103+ dendritic cells to ensure that commensal microorganisms remain outside the epithelial barrier, DCs present antigen to CD4+ T cells, leading to activation of B cells and production of microganism-specific IgM -> IgA |
front 35 where are mucosal lymphocytes activated? | back 35 activation at mucosal inductive site imprints a lymphocyte with a homing signal that directs them back to mucosal sites down regulation of CCR7, upregulation of CCR9 and MAdCAM-1 |
front 36 what is the distribution and nature of lymphocytes in the gut? | back 36 at all times, mucosal tissues are populated by antigen-activated effector cells; most other tissues only permit activated effector cells during infection effector cells primarily stimulated by antigens from commensal bacteria; others are from primary response against pathogens that aren't normally part of the gut ongoing, low0level antigen exposure continually restimulates them while their high antigen specificity and tissue's regulatory milieu keep inflammation muted |
front 37 how do B cells in the gut work? | back 37 B cells are mostly plasma cells that secrete IgA and IgM adaptive effectors are not intrinsically noninflammatory chronic activation converts the normally noninflammatory mucosal state into pathogenic inflammation mucosal B cells develop and circulate similarly to mucosal T cells |
front 38 1st wave of B cells in the gut | back 38 B cells in the lamina propria secrete IgM |
front 39 2nd wave of B cells in the gut | back 39 most of the B cells in the lamina propria become IgA-secreting plasma cells; dimeric IgA is higher affinity than IgM |
front 40 antibodies are embedded in the nucleus and help maintain a balanced environment, but... | back 40 they DO NOT fix complement they DO coat the surfaces of bacteria to impede entry into the tissues and then allow antimicrobial peptides to do the killing |
front 41 what is the role of IgA in maintaining tolerance? | back 41 anti-inflammatory antibody that limits the access of pathogens, commensal microorganisms, and food products to mucosal surfaces in a manner that avoids unnecessary damage to these delicate and vital tissues |
front 42 what are the differences between IgA1 and IgA2? | back 42 the major difference between IgA1 and IgA2 is the hinge region hinge region is twice as long IgA1 longer hinge region allows for greater 'freedom' in binding pathogens the longer hinge region is also more susceptible to pathogen-secreted proteases therefore, IgA1 predominates in mucosal areas expect for areas for those that contain protease-secreting microbes |
front 43 what tare the potential causes of and problems caused by selective IgA deficiency? | back 43 selective IgA deficiency results from an inability to class switch from IgM clinically heterogenous; results from numerous mutations |
front 44 anatomical features of mucosal immunity | back 44 intimate interactions between mucosal epithelia and lymphoid tissues discrete compartments of diffuse lymphoid tissue and more organized structures such as peyer's patches, isolated lymphoid follicles, and tonsils specialized antigen-uptake mechanisms provided by M cells in peyer's patches, adenoids, and tonsils |
front 45 effector mechanisms of mucosal immunity | back 45 activated effector T cells predominate even in the absence of infection plasma cells are in the tissues where antibodies are needed |
front 46 immunoregulatroy environment of mucosal immunity | back 46 dominant and active down regulation of inflammatory immune response to food and other innocuous environmental antigens inflammation-anergic macrophages and tolerance-inducing CD103+ dendritic cells |