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# Theoretical Analysis: LPS-TLR4-NF-κB Cascade as Neurodegeneration Target

## Key Molecular Mechanisms

The hypothesis integrates three mechanistically distinct but functionally linked pathways:

**1. Gut barrier dysfunction → peripheral inflammation**
Zonulin (pre-Haptoglobin 2) reversibly modulates intestinal tight junctions via PAR2 engagement. Elevated zonulin in dysbiosis permits LPS translocation across the gut epithelium, creating systemic endotoxemia. This is the initiating upstream event.

**2. TLR4/MyD88/NF-κB signaling**
LPS binding to TLR4 on resident gut macrophages and circulating monocytes activates MyD88-dependent signaling, driving IKK-mediated IκBα degradation and classical NF-κB activation. This transcriptional cascade upregulates NLRP3 priming signals (via NF-κB response elements) and generates pro-inflammatory cytokines including TNF-α, IL-6, and IL-1β. Critically, this creates the peripheral cytokine environment that