negative regulation of microglial cell activation

Definition

Target type: biologicalprocess

Any process that stops, prevents or reduces the frequency, rate or extent of microglial cell activation. [GO_REF:0000058, GOC:BHF, GOC:nc, GOC:TermGenie, PMID:19100238]

Microglial cell activation is a complex process that involves multiple signaling pathways and is tightly regulated to ensure proper immune responses in the central nervous system. Negative regulation of microglial activation is crucial to prevent excessive inflammation and neuronal damage. This process involves several mechanisms, including:

* **Inhibition of signaling pathways:**
* **Toll-like receptor (TLR) signaling:** TLRs recognize pathogen-associated molecular patterns (PAMPs) and trigger microglial activation. However, several mechanisms can inhibit TLR signaling, such as the expression of negative regulators like Toll-interacting protein (TOLLIP) and suppressor of cytokine signaling (SOCS) proteins.
* **Nod-like receptor (NLR) signaling:** NLRs are intracellular sensors that detect damage-associated molecular patterns (DAMPs) and activate microglial responses. Inhibition of NLR signaling can occur through molecules like NLRP3 inhibitors and autophagy.
* **Complement pathway:** The complement system can activate microglial cells via the C5a receptor. However, complement inhibitors like C1 inhibitor and C4-binding protein can suppress this pathway.

* **Production of anti-inflammatory cytokines:**
* **Interleukin-10 (IL-10):** IL-10 is a potent anti-inflammatory cytokine that suppresses microglial activation by inhibiting pro-inflammatory cytokine production and promoting anti-inflammatory gene expression.
* **Transforming growth factor-beta (TGF-β):** TGF-β is another anti-inflammatory cytokine that can inhibit microglial activation by suppressing the expression of pro-inflammatory cytokines and promoting the expression of anti-inflammatory genes.

* **Apoptotic pathways:**
* **Caspase-dependent apoptosis:** Microglial cells can undergo apoptosis, a programmed cell death pathway, to limit their activation and inflammatory responses.
* **Autophagy:** Autophagy is a cellular process that involves the degradation of cellular components, including damaged organelles and misfolded proteins. Autophagy can contribute to the negative regulation of microglial activation by removing pro-inflammatory stimuli and promoting cellular survival.

* **Modulation of microglial phenotype:**
* **M2 polarization:** Microglial cells can adopt an M2 phenotype, which is characterized by an anti-inflammatory and neuroprotective profile. M2 microglia promote tissue repair and contribute to the resolution of inflammation.

* **Neurotrophic factors:**
* **Brain-derived neurotrophic factor (BDNF):** BDNF is a neurotrophic factor that can inhibit microglial activation and promote neuronal survival. BDNF can also induce the expression of anti-inflammatory cytokines and promote microglial M2 polarization.

* **Other mechanisms:**
* **Immune checkpoint molecules:** Immune checkpoint molecules, such as PD-1 and CTLA-4, can suppress microglial activation and promote immune tolerance.
* **Extracellular matrix components:** Components of the extracellular matrix, such as laminin and fibronectin, can modulate microglial activation and contribute to tissue repair.

The negative regulation of microglial activation is crucial for maintaining neuronal function and preventing neurodegeneration. Dysregulation of this process can contribute to the development of neuroinflammatory diseases, such as Alzheimer's disease and multiple sclerosis. Therefore, understanding the mechanisms underlying the negative regulation of microglial activation is essential for developing effective therapeutic strategies for these conditions.'
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Proteins (3)

Compounds (15)