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In human CD16+ monocytes NK1R signaling upregulates inflammatory pathways and negatively regulates apoptosis

ABSTRACT: The neurokinin-1 receptor (NK1R) pathway has immunomodulatory properties and is implicated in the pathophysiology of neurodegenerative, infectious and inflammatory diseases. Monocytes are important cells in inflammation and they consist of subsets with distinct phenotypes and biological functions. NK1R signaling is elevated in conditions that alter the balance of monocyte subsets, such as in HIV infection. In order to understand the pro-inflammatory mechanism of NK1R signaling in monocyte subsets, a transcriptome study was performed using RNA sequencing. Human primary peripheral monocytes were treated with the NK1R cognate ligand, substance P (SP), prior to being sorted into CD16- and CD16+ subsets. SP treatment led to the differential expression of 38 genes in CD16- monocytes and 12 genes in CD16+ monocytes. The canonical NF-κB pathway was activated in both subsets, as indicated by the upregulation of transcripts including IL1α, IL1β, IL6, CCL3 and CCL4. In the CD16+ monocytes, NK1R signaling led to priming of the NLRP3 inflammasome and upregulated transcripts including NLRP3 and CARD16. Alternative splicing analysis showed that NK1R signaling resulted in differential exon usage of CASP1 and CARD16 in CD16+ monocytes. SP treatment altered the properties of both CD16- and CD16+ monocytes, leading to an inflammatory response with activation of the canonical NF-κB pathway in both monocyte subsets, and priming of the NLRP3 inflammasome in the CD16+ subset.

ORGANISM(S): Homo sapiens

PROVIDER: GSE109635 | GEO | 2022/01/30

REPOSITORIES: GEO

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Project description:Inflammasome, activated by pathogen-derived and host-derived danger signals, constitutes a multimolecular signaling complex that serves as a platform for caspase-1 (CASP1) activation and interleukin-1beta (IL1B) maturation. The activation of NLRP3 inflammasome requires two-step signals. The first “priming” signal (Signal 1) enhances gene expression of inflammasome components. The second “activation” signal (Signal 2) promotes the assembly of inflammasome components. Deregulated activation of NLRP3 inflammasome contributes to the pathological processes of Alzheimer’s disease (AD) and multiple sclerosis (MS). However, at present, the precise mechanism regulating NLRP3 inflammasome activation and deactivation remains largely unknown. By genome-wide gene expression profiling, we studied the molecular network of NLRP3 inflammasome activation-responsive genes in a human monocyte cell line THP-1 sequentially given two-step signals. We identified the set of 83 NLRP3 inflammasome activation-responsive genes. Among them, we found the NR4A nuclear receptor family NR4A1, NR4A2, and NR4A3, the EGR family EGR1, EGR2, and EGR3, the IkappaB family NFKBIZ, NFKBID, and NFKBIA as a key group of the genes that possibly constitute a negative feedback loop for shutting down inflammation following NLRP3 inflammasome activation. By molecular network analysis, we identified a complex network of NLRP3 inflammasome activation-responsive genes involved in cellular development and death, and immune and inflammatory responses, where transcription factors AP-1, NR4A, and EGR serve as a hub. Thus, NLRP3 inflammasome activation-responsive genes constitute the molecular network composed of a set of negative feedback regulators for prompt resolution of inflammation. To load the Signal 1 (S1), THP-1 cells were incubated for 3 hours in the culture medium with or without inclusion of 0.2 microgram/ml lipopolysaccharide (LPS). To load the Signal 2 (S2), they were incubated further for 2 hours in the culture medium with inclusion of 10 microM nigericin sodium salt dissolved in ethanol or the equal v/v% concentration of ethanol (vehicle), followed by processing for microarray analysis on Human Gene 1.0 ST Array (Affymetrix).

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In human CD16+ monocytes NK1R signaling upregulates inflammatory pathways and negatively regulates apoptosis

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