The TLR-NF-κB pathway is a major inflammatory signaling cascade where Toll-like receptor activation leads to nuclear factor kappa B (NF-κB) translocation to the nucleus, inducing transcription of inflammatory cytokines and contributing to chronic inflammation during stress.
graph TD
subgraph "Trigger"
A["[PAMPs](/en/concepts/pamps.md) / [DAMPs](/en/concepts/damps.md)<br/>([LPS](/en/concepts/lps.md), metabolic signals)"]
end
subgraph "Signaling Cascade"
B["[TLR](/en/concepts/tlr.md) Activation"]
C["MyD88 Recruitment"]
D["IRAK Kinases"]
E["TRAF6"]
F["IKK Complex<br/>Activation"]
G["IκB Phosphorylation<br/>& Degradation"]
end
subgraph "Transcriptional Output"
H["[NF-κB](/en/concepts/nf-kappab.md) Translocation<br/>to Nucleus"]
I["[TNF-α](/en/concepts/tnf-alpha.md)"]
J["[IL-1β](/en/concepts/il-1beta.md)"]
K["[IL-6](/en/concepts/interleukin-6.md)"]
L["[COX-2](/en/concepts/cox-2.md) / iNOS"]
M["Chemokines &<br/>Adhesion Molecules"]
end
A --> B
B --> C
C --> D
D --> E
E --> F
F --> G
G --> H
H --> I
H --> J
H --> K
H --> L
H --> M
style A fill:#f8d7da,stroke:#dc3545
style B fill:#f8d7da,stroke:#dc3545
style C fill:#cce5ff,stroke:#004085
style D fill:#cce5ff,stroke:#004085
style E fill:#cce5ff,stroke:#004085
style F fill:#fff3cd,stroke:#ffc107
style G fill:#fff3cd,stroke:#ffc107
style H fill:#fff3cd,stroke:#ffc107
style I fill:#d4edda,stroke:#28a745
style J fill:#d4edda,stroke:#28a745
style K fill:#d4edda,stroke:#28a745
style L fill:#d4edda,stroke:#28a745
style M fill:#d4edda,stroke:#28a745
graph TD
subgraph "Clinical Dysregulation"
S1["[Chronic stress](/en/chronic-stress)<br/>[Dysbiosis](/en/dysbiosis)<br/>Metabolic dysfunction"]
S2["Chronic [TLR](/en/concepts/tlr.md) Activation"]
S3["Sustained [NF-κB](/en/concepts/nf-kappab.md)"]
S4["[Systemic inflammation](/en/systemic-inflammation)<br/>([meta-inflammation](/en/concepts/meta-inflammation.md))"]
S5["Metabolic disease<br/>[Depression](/en/concepts/depression.md)<br/>CVD / [neuroinflammation](/en/concepts/neuroinflammation.md)"]
end
subgraph "Therapeutic Inhibition"
T1["[Polyphenols](/en/concepts/polyphenols.md)"]
T2["[Omega-3 fatty acids](/en/concepts/omega-3-fatty-acids.md)"]
T3["[Physical activity](/en/physical-activity)"]
T4["[Stress management](/en/stress-management)<br/>[Meditation](/en/concepts/meditation.md)"]
T5["[Gut barrier](/en/gut-barrier) repair<br/>[Microbiome](/en/microbiome) optimization"]
end
S1 --> S2
S2 --> S3
S3 --> S4
S4 --> S5
T1 -.->|inhibits| S3
T2 -.->|inhibits| S3
T3 -.->|reduces| S2
T4 -.->|reduces| S1
T5 -.->|reduces TLR ligands| S2
style S1 fill:#f8d7da,stroke:#dc3545
style S2 fill:#f8d7da,stroke:#dc3545
style S3 fill:#fff3cd,stroke:#ffc107
style S4 fill:#fff3cd,stroke:#ffc107
style S5 fill:#f8d7da,stroke:#dc3545
style T1 fill:#d4edda,stroke:#28a745
style T2 fill:#d4edda,stroke:#28a745
style T3 fill:#d4edda,stroke:#28a745
style T4 fill:#d4edda,stroke:#28a745
style T5 fill:#d4edda,stroke:#28a745
TLR activation (by PAMPs, DAMPs, or metabolic signals) recruits adaptor proteins (primarily MyD88). This triggers a signaling cascade involving IRAK kinases and TRAF6, leading to activation of the IKK complex. IKK phosphorylates IκB (inhibitor of κB), marking it for degradation. Free NF-κB translocates to the nucleus and binds DNA to promote transcription of genes encoding: inflammatory cytokines (TNF-α, IL-1β, Interleukin-6), chemokines, adhesion molecules, and enzymes (COX-2, iNOS). This pathway is one of the main mechanisms by which chronic stress, metabolic dysfunction, and dysbiosis generate systemic inflammation.
The TLR-NF-κB pathway is central to understanding how diverse stress (psychology, metabolic, microbial) converge to produce inflammation in cPNI. Chronic activation contributes to: metabolic diseases, Depression, cardiovascular disease, neuroinflammation, and autoimmune conditions. The pathway provides mechanistic explanation for stress-inflammation connection. Clinical interventions targeting this pathway include: Polyphenols (inhibit NF-κB), Omega-3 fatty acids, physical activity (reduces TLR expression), stress management, improving gut barrier function (reduces TLR4 ligands), and optimizing microbiome (reduces inflammatory TLR ligands).
- Links TLR activation to inflammatory gene transcription
- Key transcription factor: NF-κB
- Induces: TNF-α, IL-1β, Interleukin-6, COX-2, iNOS
- Major contributor to inflammation during chronic stress
- Activated by: PAMPs, DAMPs, LPS, oxylipins
- Inhibited by: Polyphenols, Omega-3, physical activity, Meditation
- Loneliness increases TLR4 pathway polarization
- Central to meta-inflammation and inflammaging