TABLE 2.

Overview of studies performed to investigate TLR4 and NF-κB’s roles in neuropsychiatric disorders.

Study	Method	Condition of Brain/Behavior	Finding
(118)	Measure TLR4 and NF-κB levels in human postmortem brains	Schizophrenia	PFC: (1) ↓ TLR4, (2) ↑ NF-κB Cerebellum: (1) ↑ TLR4, (2) ↓ NF-κB
(116)	Measure NF-κB levels in postmortem human brains	Autism spectrum conditions	↑ NF-κB levels especially in microglia
(121)	Associative study on TLR4 single gene polymorphisms and MDD	Individuals with higher suicide and anxiety scores	↑ TLR4 single gene polymorphisms
(122)	Associative Study of epigenetic effects of TLR4 on severity of symptoms	Higher severity of depressive symptoms	↑ methylation levels of TLR4-associated CpGs
(123)	Measure levels of active NF-κB in an early-life stress rat model	Depression susceptible phenotype	↑ activated NF-κB
		Depression resilient phenotype	↑ inactivated NF-κB
(124)	NF-κB inhibited in mice model to see behavioral changes	Improved depressive-like behaviors	↓ overactivated NF-κB
(125)	Suppressing TLR4-NF-κB pathway in mice	Inhibits depression-like behavior	↓ signaling of TLR4-NF-κB pathway

↑, increased; ↓, decreased; TLR4, toll-like receptor 4; NFκB, nuclear factor kappa-light-chain-enhancer of activated B cells; PFC, prefrontal cortex.