The antipsychotic spiperone attenuates inflammatory response in cultured microglia via the reduction of proinflammatory cytokine expression and nitric oxide production

Anti-inflammatory effects of synthetic compound KT-14480 in lipopolysaccharide-stimulated microglia cells

Objectives

Neurodegenerative diseases have a prominent inflammatory component. Several synthetic fluorovinyloxyacetamide derivatives were screened by microglia cell-based assay in order to identify novel compounds that inhibit the inflammatory activation of microglia.

Methods

Microglia cell-based nitric oxide assay was employed to screen the compounds. RT-PCR and ELISA were conducted to evaluate the expression of inflammatory gene expression. Molecular mechanisms were determined by western blot analysis, immunocytochemistry, EMSA, and microglia/neuroblastoma cocultures.

Key findings

A fluorovinyloxyacetamide compound KT-14480 significantly suppressed nitric oxide production in lipopolysaccharide-stimulated microglia cells. KT-14480 also suppressed the secretion and expression of several inflammatory mediators such as tumour necrosis factor-α, interleukin-1β and inducible nitric oxide synthase. Additional studies showed that these inhibitory effects were accompanied by the suppression of nuclear factor-κB and neuroprotection in the microglia/neuroblastoma coculture.

Conclusions

Our results indicate that the anti-inflammatory compound KT-14480 may be a novel therapeutic drug candidate against neuroinflammatory diseases.

Microglia signaling as a target of donepezil

Donepezil is a reversible and noncompetitive cholinesterase inhibitor. The drug is considered as a first-line treatment in patients with mild to moderate Alzheimer's disease. Recently, anti-inflammatory and neuroprotective effects of the drug have been reported. "Cholinergic anti-inflammation pathway" has major implications in these effects. Here, we present evidence that donepezil at 5-20 microM directly acts on microglial cells to inhibit their inflammatory activation. Our conclusion is based on the measurement of nitric oxide and proinflammatory mediators using purified microglia cultures and microglia cell lines: donepezil attenuated microglial production of nitric oxide and tumor necrosis factor (TNF)-alpha, and suppressed the gene expression of inducible nitric oxide synthase, interleukin-1 beta, and TNF-alpha. Subsequent studies showed that donepezil inhibited a canonical inflammatory NF-kappaB signaling. Microglia/neuroblastoma coculture and animal experiments supported the anti-inflammatory effects of donepezil. Based on the studies using nicotinic acetylcholine receptor antagonists, the donepezil inhibition of microglial activation was independent of acetylcholine and its receptor. Thus, inflammatory activation signaling of microglia may be one of the direct targets of donepezil in the central nervous system. It should be noted, however, that there is a large gap between the therapeutic dose of the drug used clinically and the concentration of the drug that exerts the direct action on microglial cells.

Clinical perspectives on autoimmune processes in schizophrenia

This article reviews the epidemiology of autoimmune conditions in schizophrenia, symptom manifestations of autoimmune conditions resembling schizophrenia, and the immunological changes observed in schizophrenia; and reflects on their associations with neurodevelopment, neurodegeneration, clinical course, and management of schizophrenia.

Cytokines and schizophrenia: Microglia hypothesis of schizophrenia

The etiology of schizophrenia remains unclear, while there has been a growing amount of evidence for the neuroinflammation and immunogenetics, which are characterized by an increased serum concentration of several pro-inflammatory cytokines. Despite the fact that microglia comprise only <10% of the total brain cells, microglia respond rapidly to even minor pathological changes in the brain and may contribute directly to the neuronal degeneration by producing various pro-inflammatory cytokines and free radicals. In many aspects, the neuropathology of schizophrenia has recently been reported to be closely associatedwith microglial activation. Previous studies have shown the inhibitory effects of some typical/atypical antipsychotics on the release of inflammatory cytokines and free radicals from activated microglia, both of which have recently been known to cause a decrease in neurogenesis as well as white matter abnormalities in the brains of patients with schizophrenia. The microglia hypothesis of schizophrenia may shed new light on the therapeutic strategy for schizophrenia.