defense response to fungus

Definition

Target type: biologicalprocess

Reactions triggered in response to the presence of a fungus that act to protect the cell or organism. [GOC:ai]

Defense response to fungus is a complex biological process that involves a coordinated effort by the immune system to recognize and eliminate fungal pathogens. It is essential for maintaining host health and preventing fungal infections. Here is a detailed description of the process:

**1. Recognition of Fungal Pathogens:**
- **Pattern Recognition Receptors (PRRs):** Plant and animal cells possess PRRs that recognize pathogen-associated molecular patterns (PAMPs) found on fungal cell walls, such as chitin, β-glucans, and lipopolysaccharides. These PRRs include Toll-like receptors (TLRs), lectins, and membrane-bound receptors.
- **Damage-Associated Molecular Patterns (DAMPs):** Host cells release DAMPs during fungal invasion, which can activate immune cells and trigger inflammation.

**2. Activation of Immune Cells:**
- **Immune Cells Involved:** The immune cells that play a critical role in defense response to fungus include macrophages, neutrophils, dendritic cells, and T cells.
- **Signal Transduction Pathways:** Upon recognition of PAMPs or DAMPs, PRRs initiate signaling cascades that activate downstream transcription factors and lead to the production of cytokines and chemokines.
- **Cytokine and Chemokine Production:** These signaling pathways result in the release of cytokines, such as TNF-α, IL-1β, and IL-6, and chemokines, which attract immune cells to the site of infection.

**3. Inflammatory Response:**
- **Inflammation:** The release of cytokines and chemokines triggers an inflammatory response, characterized by redness, swelling, heat, and pain. This response helps to isolate the fungal infection and prevent its spread.

**4. Phagocytosis and Killing of Fungi:**
- **Phagocytosis:** Macrophages and neutrophils engulf and destroy fungal cells through phagocytosis.
- **Antimicrobial Mechanisms:** Phagocytic cells employ various antimicrobial mechanisms to kill fungi, including the production of reactive oxygen species (ROS), nitric oxide (NO), and antifungal enzymes, such as lysozyme.
- **Neutrophil Extracellular Traps (NETs):** Neutrophils can release NETs, which are fibrous structures composed of DNA and antimicrobial proteins that trap and kill fungal cells.

**5. Adaptive Immune Response:**
- **Antigen Presentation:** Dendritic cells engulf fungal antigens and present them to T cells, initiating an adaptive immune response.
- **T Cell Activation:** T cells are activated and differentiate into effector T cells, including cytotoxic T lymphocytes (CTLs) and T helper cells (Th cells).
- **CTLs:** CTLs directly kill fungal cells infected with pathogens.
- **Th cells:** Th cells produce cytokines that further enhance the immune response, activate other immune cells, and promote the production of antibodies.

**6. Antibody Production:**
- **B Cell Activation:** B cells are activated by fungal antigens and differentiate into antibody-producing plasma cells.
- **Antifungal Antibodies:** Antibodies can bind to fungal cells, neutralize their infectivity, and facilitate their clearance by phagocytes.

**7. Resolution of Infection:**
- **Immune Clearance:** The coordinated immune response leads to the elimination of the fungal infection and the restoration of tissue homeostasis.

**8. Immunological Memory:**
- **Memory T and B Cells:** The adaptive immune response generates memory T and B cells, which provide long-term protection against future fungal infections by allowing for a faster and more robust immune response.

Defense response to fungus is an essential process that protects against fungal infections. The recognition of fungal PAMPs and DAMPs, activation of immune cells, and the production of antimicrobial molecules all contribute to the successful clearance of fungal pathogens. However, fungal pathogens can evade the host immune system by developing strategies to resist antifungal drugs or to suppress the immune response. In such cases, the infection can become chronic and potentially life-threatening.'
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Proteins (4)

Compounds (67)