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Bio lecture 03/10

Overview of Innate Immunity

  • Focus on innate immunity and inflammatory response

  • Revisit the signaling pathway in Drosophila

Learning Outcomes

  • Understanding the inflammatory response

  • Recognizing the pathways activated by pathogen recognition

Drosophila Immune Response

  • Activation of Innate Immunity:

    • Flies recognize fungal pathogens through specific surface patterns.

    • Pathway activation examples: Toll receptors, Pele kinase, cactus, and dorsal proteins.

  • Signaling Cascade:

    • Pathogen Activation: Fungal pathogen detected by Toll receptors.

    • Intracellular Signaling: Toll receptors activate Pele kinase, leading to the phosphorylation of cactus.

    • Degradation of cactus: This allows dorsal protein to enter the nucleus and activate antifungal gene transcription.

Signaling Pathways

  • Illustration of Pathways:

    • Arrow diagrams used to denote activation processes.

    • Think about effects of mutations at different points in the pathway.

  • Application to Humans:

    • Similar innate immune response in humans with pattern recognition receptors like Toll-like receptors (TLRs).

    • Reinforces the concept of evolutionary conservation in immune systems.

Innate vs. Adaptive Immunity

  • Key Characteristics of Innate Immunity:

    • No memory involved; consistent response to infections.

    • Example: Physical barriers (skin, mucus) and mucus traps pathogens.

  • Overview of Adaptive Immunity:

    • Involves B-cells and T-cells; develops over time and offers memory.

    • Adaptive immunity integrates signals from the innate response to amplify future defense against recognized pathogens.

Inflammatory Response Mechanism

  • Initial Response:

    • Wound exposure followed by recognition of bacteria by macrophages.

    • Platelets form clots to reduce blood loss and prevent infection at wound sites.

  • Role of Macrophages:

    • Perceive infection and secrete chemokines to recruit other immune cells.

    • Chemokines: Attract additional immune cells to the site of injury.

Cytokine Release and Inflammation

  • Mast Cell Activation:

    • Release of histamines leads to vasodilation and increased permeability of blood vessels.

    • Increased blood flow to promote immune cell access.

  • Neutrophil Function:

    • Newly recruited neutrophils and macrophages engage in phagocytosis to destroy pathogens and secrete further signaling molecules (e.g., prostaglandins for fever induction).

Consequences of Inflammation

  • Physical Symptoms:

    • Swelling, redness, and warmth at infection site.

    • Mucus production like runny nose and tearing to remove pathogens.

  • Potential for Hyperactive Responses:

    • In some cases, excess inflammation can occur, leading to tissue damage.

Importance of the Innate Response

  • Goals of Innate Immunity:

    • Restore physical barrier, limit damage, eliminate pathogens, and alert adaptive immune response.

  • Understanding the initial innate reactions helps in comprehending broader immune functionalities.

Anti-histamines and Immune Drugs

  • Common Treatments:

    • Anti-histamines to alleviate symptoms dampen the immune response.

    • Acknowledgment of the discomfort caused by natural inflammation responses.

Autoimmunity and Immune Dysfunction

  • Dysregulation of Immune System:

    • Autoimmune diseases arise when the immune system misidentifies self-tissues as foreign.

    • Reflects on importance of regulatory mechanisms in immune responses.

Human Microbiome and Immune Function

  • Concept of Microbiome:

    • Relationship between human cells and diverse microbial populations.

    • Microbiomes vary across body environments, influencing health outcomes.

  • Research Significance:

    • Understanding how birth processes (vaginal vs c-section) can influence the microbiome and future disease risks.