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HIV infection modulates IL-1? response to LPS stimulation through a TLR4-NLRP3 pathway in human liver macrophages.

ABSTRACT: IL-1? is an important mediator of innate inflammatory responses and has been shown to contribute to liver injury in a number of etiologies. HIV patients have increased necroinflammation and more rapid fibrosis progression in chronic liver injury compared to non-HIV-infected patients. As the resident liver macrophage is critical to the IL-1? response to microbial translocation in chronic liver disease, we aim to examine the impact of HIV-1 and LPS stimulation on the IL-1? response of the resident hepatic macrophages. We isolated primary human liver macrophages from liver resection specimens, treated them with HIV-1BaL and/or LPS ex vivo, examined the IL-1? response, and then studied underlying mechanisms. Furthermore, we examined IL-1? expression in liver tissues derived from HIV-1 patients compared to those with no underlying liver disease. HIV-1 up-regulated TLR4 and CD14 expression on isolated primary CD68+ human liver macrophages and contributed to the IL-1? response to LPS stimulation as evidenced by TLR4 blocking. Nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) was shown to be involved in the IL-1? response of liver macrophages to HIV-1 infection and NLRP3 blocking experiments in primary CD68+ liver macrophages confirmed the contribution of the NLRP3-caspase 1 inflammatory signaling pathway in the IL-1? response. High in situ IL-1? expression was found in CD68+ cells in human liver tissues from HIV-1-infected patients, suggesting a critical role of IL-1? responses in patients infected by HIV. HIV infection sensitizes the IL-1? response of liver macrophages to LPS through up-regulation of CD14 and TLR4 expression and downstream activation of the NLRP3-caspase 1 pathway. These findings have implications for enhanced immune activation in HIV+ patients and mechanisms for rapid fibrosis progression in patients with chronic liver injury.

SUBMITTER: Zhang L

PROVIDER: S-EPMC6685708 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature

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HIV infection modulates IL-1β response to LPS stimulation through a TLR4-NLRP3 pathway in human liver macrophages.

Zhang Lumin L Mosoian Arevik A Schwartz Myron E ME Florman Sander S SS Gunasekaran Ganesh G Schiano Thomas T Fiel M Isabel MI Jiang Wei W Shen Qi Q Branch Andrea D AD Bansal Meena B MB

Journal of leukocyte biology 20190218 4

IL-1β is an important mediator of innate inflammatory responses and has been shown to contribute to liver injury in a number of etiologies. HIV patients have increased necroinflammation and more rapid fibrosis progression in chronic liver injury compared to non-HIV-infected patients. As the resident liver macrophage is critical to the IL-1β response to microbial translocation in chronic liver disease, we aim to examine the impact of HIV-1 and LPS stimulation on the IL-1β response of the resident ...[more]

PMID: 30776150

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Project description:Inflammation and metabolism are intricately linked during inflammatory diseases in which activation of the nucleotide-binding domain-like receptors Family Pyrin Domain Containing 3 (NLRP3) inflammasome, an innate immune sensor, is critical. Several factors can activate the NLRP3 inflammasome, but the nature of the link between NLRP3 inflammasome activation and metabolism remains to be thoroughly explored. This study investigates whether the small molecule inhibitor of the NLRP3 inflammasome, MCC950, modulates the lipopolysaccharide (LPS) -and amyloid-β (Aβ)-induced metabolic phenotype and inflammatory signature in macrophages. LPS + Aβ induced IL-1β secretion, while pre-treatment with MCC950 inhibited this. LPS + Aβ also upregulated IL-1β mRNA and supernatant concentrations of TNFα, IL-6 and IL-10, however these changes were insensitive to MCC950, confirming that MCC950 specifically targets inflammasome activation in BMDMs. LPS + Aβ increased glycolysis and the glycolytic enzyme, PFKFB3, and these effects were decreased by MCC950. These findings suggest that NLRP3 inflammasome activation may play a role in modulating glycolysis. To investigate this further, the effect of IL-1β on glycolysis was assessed. IL-1β stimulated glycolysis and PFKFB3, mimicking the effect of LPS + Aβ and adding to the evidence that inflammasome activation impacts on metabolism. This contention was supported by the finding that the LPS + Aβ-induced changes in glycolysis and PFKFB3 were attenuated in BMDMs from NLRP3-deficient and IL-1R1-deficient mice. Consistent with a key role for PFKFB3 is the finding that the PFKFB3 inhibitor, 3PO, attenuated the LPS + Aβ-induced glycolysis. The data demonstrate that activation of the NLRP3 inflammasome, and the subsequent release of IL-1β, play a key role in modulating glycolysis via PFKFB3. Reinstating metabolic homeostasis by targeting the NLRP3 inflammasome-PFKFB3 axis may provide a novel therapeutic target for treatment of acute and chronic disease.

Project description:ObjectiveC/EBPβ, a crucial transcription factor, regulates innate immunity and inflammatory responses. However, the role played by C/EBPβ in alveolar macrophage (AM) inflammatory responses remains unknown. This study aimed to investigate the role and mechanism of C/EBPβ in alveolar macrophages (AMs) from the transcriptional level and to search for natural compounds targeting C/EBPβ.MethodsRat AMs were infected with Lv-sh-C/EBPβ and treated with LPS, and the expression levels of iNOS, TNF-α, IL-6, and IL-1β were measured by RT-qPCR, Western blotting, and ELISA. Mechanistically, transcriptome sequencing (RNA-seq) revealed changes in gene expression patterns in AMs after LPS stimulation and C/EBPβ knockdown. Functional enrichment analyses and rescue experiments identified and validated inflammation-associated cell signaling pathways regulated by C/EBPβ. Furthermore, virtual screening was used to search for natural compounds that inhibit C/EBPβ with the structure of helenalin as a reference.ResultsFollowing stimulation with LPS, AMs exhibited an increased expression of C/EBPβ. C/EBPβ knockdown significantly decreased the expression levels of inflammatory mediators. A total of 374 differentially expressed genes (DEGs) were identified between LPS-stimulated C/EBPβ knockdown and negative control cells. The NOD-like receptor signaling may be a key target for C/EBPβ, according to functional enrichment analyses of the DEGs. Further experiments showed that the muramyl dipeptide (MDP, NOD2 agonist) reversed the downregulation of inflammatory mediators and the NF-κB pathway caused by the C/EBPβ knockdown. The virtual screening revealed that N-caffeoyltryptophan, orilotimod, and petasiphenone have comparable pharmacological properties to helenalin (a known C/EBPβ inhibitor) and demonstrate a great binding capacity to C/EBPβ.ConclusionAblation of C/EBPβ may attenuate LPS-induced inflammatory damage in AMs by inhibiting the NOD2 receptor signaling pathway. Three natural compounds, N-caffeoyltryptophan, orilotimod, and petasiphenone, may be potential C/EBPβ inhibitors.

Dataset Information

HIV infection modulates IL-1? response to LPS stimulation through a TLR4-NLRP3 pathway in human liver macrophages.

Publications

HIV infection modulates IL-1β response to LPS stimulation through a TLR4-NLRP3 pathway in human liver macrophages.

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