1 - Inmunidad innata
Inmunología: Mecanismos Inmunes Innatos
The seminar discusses innate immune mechanisms that prevent infections and the adaptive response when infections occur.
Microorganisms Surrounding Us
- Microorganisms, some potentially pathogenic, surround us.
- Despite exposure to many microorganisms, successful infection resolution is due to an efficient immune system.
- Most encountered microorganisms are eliminated quickly; virulence and inoculum size affect elimination time.
Pathogenic Microorganisms and Immune Responses
- Pathogenic microorganisms have evolved evasion mechanisms against the immune system.
- Adaptive responses are activated against highly pathogenic microorganisms.
Infection Consequences and Microorganism Types
- Only a small proportion of microorganisms are pathogenic; they can cause infectious diseases by colonizing or invading cells.
- The immune system recognizes and recruits antimicrobial activities to combat invading microorganisms.
Diversity of Pathogens
- Various pathogens (bacteria, viruses, parasites, fungi) have different replication strategies and structures.
- Differences exist in how pathogens replicate within host cells.
Host Defense Mechanisms
- Host defenses depend on the ability to evade or resist pathogens' immune evasion mechanisms.
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This section discusses the adaptive immune response and the involvement of effector cells in combating microorganisms.
Adaptive Immune Response
- The response depends on the size of the inoculum and the replicative capacity of the microorganism.
- Involves activation of adaptive effector cells like T and B lymphocytes with specific receptors for recognizing microbial structures.
- Explores innate effector mechanisms and various cells and soluble factors participating in the immune response.
- Highlights that besides leukocytes, other cell types possess recognition mechanisms to respond to pathogens.
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This part delves into precursor cells involved in immune responses and their differentiation.
Precursor Cells in Immune Response
- Hematopoietic precursor gives rise to myeloid lineage (neutrophils, basophils, etc.) and lymphoid lineage (lymphocytes).
- Different leukocytes play varying roles against different pathogens based on their relevance.
- Activation triggers involve microorganisms or tissue damage, leading to cellular responses for pathogen elimination.
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Discusses how innate immunity is activated by pathogens or tissue damage, leading to inflammation as a key event.
Innate Immunity Activation
- Pathogens activate innate immunity; tissue damage can also trigger responses involving various cell types.
- Events post-innate immune activation include inflammation characterized by heat, pain, swelling, and redness.
mecanismos químicos y físicos de prevención
This section discusses the chemical and physical mechanisms that prevent infections in the body.
Chemical Mechanisms
- The body produces antimicrobial peptides like lysozyme and lactoferrin to combat infections.
Physical Mechanisms
- Intestinal mucosa regenerates daily, preventing infections.
- Respiratory tract cilia sweep mucus containing trapped microorganisms towards the throat for elimination.
respuesta innata a la infección
This part covers the innate response to infection and its associated inflammatory signs.
Signs of Infection
- Infections trigger symptoms like tumor, heat, redness, and pain due to inflammation.
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This section discusses the components of the immune system, focusing on antibodies and their specific roles.
Components of the Immune System
- Antibodies like IgM and IgG play a crucial role in immunity.
- Specific antibodies target molecules that individuals have been previously exposed to.
- Antibodies are reactive against various molecular structures with low affinity.
- Tissue contains immune system components in small amounts.
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This part explains how innate immunity cells recognize pathogens through pattern recognition receptors (PRRs).
Pattern Recognition Receptors
- PRRs, also known as pattern recognition receptors, identify pathogen-associated molecular patterns (PAMPs).
- PRRs were initially thought to be present only in genes but are now known to recognize non-pathogenic microorganisms.
- PAMPs are molecules released during cellular damage or altered conditions.
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The discussion focuses on shared structures among microorganisms recognized by innate immunity cells.
Shared Structures Recognized by Innate Immunity
- Essential structures for pathogen survival are targeted by innate immunity receptors.
- These structures are invariant and shared among large groups of microorganisms.
- Examples include lipopolysaccharides found in gram-negative bacteria.
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This part elaborates on how innate immunity recognizes specific components of pathogens through receptors.
Recognition of Pathogen Components
- Cells possess receptors capable of recognizing specific components like LPS and peptidoglycans.
- Microbial nucleic acids such as DNA and RNA can also be detected by pattern recognition receptors.
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The segment discusses the release and detection of hidden molecules by pattern recognition receptors.
Detection Mechanisms of Hidden Molecules
- Molecules hidden within cells are released upon cell death or stress-induced mitochondrial damage.
Fragmentation of Components and Recognition Receptors
The discussion covers the fragmentation of cellular components, such as extracellular matrix producers, leading to the activation of recognition receptors upon tissue damage.
Fragmentation Process
- Cellular components fragment during tissue damage.
- Crystals like uric acid can activate pattern recognition receptors.
- Molecules like HMGB1 can trigger receptors upon cell death.
Activation of Complement System and Phagocytosis
Details the activation of the complement system by bacteria, leading to enhanced phagocytosis through receptor recognition.
Complement Activation
- Bacteria induce complement system activation.
- Phagocytic cells recognize C3b-coated bacteria efficiently.
Role of Innate Immune Cells in Pathogen Recognition
Explores how innate immune cells use various receptors to identify pathogens and initiate immune responses.
Pathogen Recognition
- Innate immune cells possess diverse complement receptors.
- Mast cells respond to C3 and C5 recognition with granule release.
Immune Response Cascade Upon Pathogen Detection
Describes the cascade of events following pathogen detection, including vasodilation and leukocyte recruitment.
Immune Response Cascade
- Endothelial cell response leads to vasodilation.
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This section discusses the activation of complement components and their role in enhancing recognition and phagocytosis.
Activation of Complement Components
- The component S3, present in low quantities in interstitial spaces, can enhance complement-mediated recognition.
- Complement activation can lead to the production of toxins like components 36 and 5a.
- Activation may also generate a membrane attack complex on the surface of invading microorganisms, leading to their death.
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This part explains how the complement system can be activated through three different pathways: alternative, lectin, and classical pathways.
Pathways of Complement Activation
- Complement can be activated via the alternative, lectin, or classical pathway.
- The alternative pathway is triggered by spontaneous hydrolysis of C3 under normal conditions.
- Cells have regulators to prevent complement activation on self-cells in the absence of infection.
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This section delves into the detailed process of complement activation through different pathways.
Detailed Process of Complement Activation
- Complement can be activated by three pathways: alternative, lectin, and classical.
- The lectin pathway usually activates after 24-48 hours post-infection initiation.
- The classical pathway requires antigen-antibody complex formation for activation.
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Here we explore how complement activation leads to the generation of enzymatic complexes that play crucial roles in immune responses.
Generation of Enzymatic Complexes
- Activation leads to the formation of convertase enzymes like C3 convertase with varying components based on the activating pathway.
- Convertases cleave C3 into active components such as C3a and C3b.
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This part emphasizes that regardless of the activation pathway, all paths lead to generating a key enzymatic complex called convertase decente.
Common Outcome of Pathways
- All three pathways result in generating a key enzymatic complex known as convertase decente.
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This segment highlights that understanding the common outcome across all pathways is crucial despite variations in enzyme composition based on each pathway's activation.
Importance Across Pathways
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This section discusses the release of active components by mast cells, particularly histamine, contributing to increased vascular permeability and vasodilation.
Mast Cell Activation
- Histamine released by mast cells increases vascular permeability.
- Mast cell activation leads to vasodilation and enhanced leukocyte adhesion on endothelial surfaces.
- Increased expression of adhesion molecules on the endothelium facilitates leukocyte migration towards infection sites.
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This section discusses the process of infection and how certain proteins access the infection site.
Accessing the Infection Site
- The increase in vascular permeability at the tissue's infection site allows proteins like C-reactive protein and plasma mannose-binding lectin to access the focus of infection.
- The lectin pathway of complement activation is triggered when there is a sufficient amount of mannose-binding lectin at the infection site.
- Activation of the lectin pathway occurs due to an accumulation of mannose-binding lectin at the infection site, leading to subsequent processes.
- Macrophage activation, synthesis of N-1, and liver production of significant amounts of lectins are necessary for complement activation by reaching the infection site.
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This part delves into how C-reactive protein induces complement system activation and its impact on microbial replication.
Impact on Microbial Replication
- C-reactive protein can activate the complement system through a different pathway, contributing to actions against microbes but not completing them fully.
- Proinflammatory cytokines IL-1 and IL-6 can mobilize neutrophils from bone marrow to increase their presence in peripheral blood, aiding in fighting infections.
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The section discusses the recruitment of immune cells to combat infections and the mechanisms involved in phagocytosis.
Recruitment of Immune Cells
- Neutrophils and macrophages are recruited to infection sites for phagocytic functions.
- Neutrophils, being highly efficient, are primarily responsible for phagocytizing and destroying bacteria.
Phagocytosis Mechanisms
- Cells engulf microorganisms through phagocytosis, leading to destruction within vesicles.
- Microbicidal functions involve oxygen-dependent and independent mechanisms for microbial elimination.
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This part explains how neutrophils activate microbicidal mechanisms upon engulfing bacteria through phagocytosis.
Activation of Microbicidal Mechanisms
- Neutrophils contain granules with antimicrobial enzymes that are released upon fusion with phagosomal membranes.
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The section discusses the importance of certain mechanisms in cell destruction and the activation process of an enzyme called NADPH oxidase.
Mechanisms of Cell Destruction
- Certain mechanisms are crucial for destroying harmful microorganisms inside cells.
- Safeguard mechanisms prevent the production of reactive oxygen species unnecessarily, like NADPH oxidase which requires assembly for activation.
- NADPH oxidase is composed of membrane and cytoplasmic components that assemble upon cell activation.
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This section explains the activation process of NADPH oxidase and its role in combating microorganisms within cells.
Activation Process of NADPH Oxidase
- Upon phagocytosis, components of NADPH oxidase translocate to the membrane forming an active oxidase complex.
- The activated complex generates reactive oxygen species that act on microorganisms, aiding in their destruction.
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The section delves into extracellular trapping mechanisms by neutrophils to combat pathogens effectively.
Extracellular Trapping Mechanisms
- Neutrophils release traps called NETs containing chromatin and antimicrobial proteins to capture and eliminate pathogens extracellularly.
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This section discusses the process of cell activation and rupture, as well as the release of DNA in response to infection.
Cell Activation and Rupture
- Cells become activated and move actively, leading to nucleus changes.
- The release of DNA occurs when cells rupture due to certain events.
- Macrophages play a crucial role in responding to infections by releasing various mediators.
- Neutrophils and macrophages differ in their abilities to produce cytokines and inflammation mediators.
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This section focuses on the roles of different immune cells in infection response and the production of cytokines.
Immune Cell Response
- Neutrophils release fewer cytokines compared to macrophages during infection.
- Macrophages vary their cytokine production based on activation receptors.
- Different pathogens trigger distinct immune responses through varying cytokine releases.
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This part delves into resident tissue cells contributing to immune alertness against invading microorganisms.
Tissue Resident Cells
- Apart from discussed cells, tissue-resident innate lymphocytes aid in immune response amplification.
- Innate lymphoid group 1, 2, and 3 cells respond differently based on environmental cues.
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The discussion continues with the activation of innate immune cells by early-produced cytokines during infections.
Activation of Innate Immune Cells
- Group 1 includes NK cells responding to interferon gamma for intracellular pathogen removal.
- Group 2 produces IL-13 and IL-15 for extracellular pathogen elimination.
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This part explains how specific cell types respond to bacterial infections through cytokine interactions.
Response Mechanisms
- Macrophages or dendritic cells produce IL1β and IL23 impacting group 3 lymphoid cells' responses.
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The section discusses the migration of cells to lymph nodes for immune response activation and the role of specific receptors in combating pathogens.
Cell Migration and Immune Response Activation
- Cells can detach from tissue cells and migrate to secondary lymph nodes draining the infected area.
- These cells contribute to activating adaptive responses by engaging T lymphocytes with specific pathogen receptors.
- Various mechanisms work together to eliminate or contain infections, preparing for a targeted adaptive response against the microorganism.
- Adaptive responses enhance innate effector mechanisms like phagocytosis by neutrophils and macrophages, leading to more precise and efficient pathogen clearance.
afortunadamente frente a muchos microorganismos
The speaker discusses how our immune system can counteract evasion mechanisms of many microorganisms, except in cases of immunodeficiency.
Immune Response to Microorganisms
- Our immune system can effectively counteract evasion mechanisms of many microorganisms.
- Challenges arise in patients with immunodeficiencies where the immune response may not be sufficient.