LPS-induced TIR domain complex acetylation activated TLR4/MAL/MyD88 signal pathway in sepsis [scRNA-Seq]
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ABSTRACT: Among the diseases caused by Toll-like receptor 4 (TLR4) abnormal activation by bacterial endotoxin, sepsis is the most dangerous one. The reprogramming of macrophages plays a crucial role in orchestrating the pathogenesis of sepsis. However, the precise mechanism underlying TLR4 activation in macrophages remained incompletely understood. Our studies revealed that upon lipopolysaccharide (LPS) stimulation, CREB-binding protein (CBP) was recruited to the TLR4 signalosome complex and resulted in pronounced acetylation in the TIR domains of TLR4, Myeloid differentiation factor 88 (MyD88) and MyD88 adapter-like (MAL), which significantly enhanced the activation of the NF-κB signaling pathway and polarization of M1 macrophages. In sepsis patients, significantly elevated TLR4-TIR acetylation was detected in CD16+ monocytes combined with elevated expression of M1 macrophage markers and production of pro-inflammatory cytokines. In contrast, histone deacetylase 1 (HDAC1) served as a key deacetylase in the deacetylation of the TIR domain complex. The inhibition of HDAC1 accelerated sepsis-associated syndromes, while the inhibition of CBP alleviated this process. Overall, our findings highlighted the crucial role of TIR domain complex acetylation in the regulation of inflammatory immune response and suggested that the reversible acetylation of the complex emerged as a promising therapeutic target for M1 macrophages during the progression of sepsis.
Project description:Among the diseases caused by Toll-like receptor 4 (TLR4) abnormal activation by bacterial endotoxin, sepsis is the most dangerous one. The reprogramming of macrophages plays a crucial role in orchestrating the pathogenesis of sepsis. However, the precise mechanism underlying TLR4 activation in macrophages remained incompletely understood. Our studies revealed that upon lipopolysaccharide (LPS) stimulation, CREB-binding protein (CBP) was recruited to the TLR4 signalosome complex and resulted in pronounced acetylation in the TIR domains of TLR4, Myeloid differentiation factor 88 (MyD88) and MyD88 adapter-like (MAL), which significantly enhanced the activation of the NF-κB signaling pathway and polarization of M1 macrophages. In sepsis patients, significantly elevated TLR4-TIR acetylation was detected in CD16+ monocytes combined with elevated expression of M1 macrophage markers and production of pro-inflammatory cytokines. In contrast, histone deacetylase 1 (HDAC1) served as a key deacetylase in the deacetylation of the TIR domain complex. The inhibition of HDAC1 accelerated sepsis-associated syndromes, while the inhibition of CBP alleviated this process. Overall, our findings highlighted the crucial role of TIR domain complex acetylation in the regulation of inflammatory immune response and suggested that the reversible acetylation of the complex emerged as a promising therapeutic target for M1 macrophages during the progression of sepsis.
Project description:Among the diseases caused by Toll-like receptor 4 (TLR4) abnormal activation by bacterial endotoxin, sepsis is the most dangerous one. The reprogramming of macrophages plays a crucial role in orchestrating the pathogenesis of sepsis. However, the precise mechanism underlying TLR4 activation in macrophages remained incompletely understood. Our studies revealed that upon lipopolysaccharide (LPS) stimulation, CREB-binding protein (CBP) was recruited to the TLR4 signalosome complex and resulted in pronounced acetylation in the TIR domains of TLR4, Myeloid differentiation factor 88 (MyD88) and MyD88 adapter-like (MAL), which significantly enhanced the activation of the NF-κB signaling pathway and polarization of M1 macrophages. In sepsis patients, significantly elevated TLR4-TIR acetylation was detected in CD16+ monocytes combined with elevated expression of M1 macrophage markers and production of pro-inflammatory cytokines. In contrast, histone deacetylase 1 (HDAC1) served as a key deacetylase in the deacetylation of the TIR domain complex. The inhibition of HDAC1 accelerated sepsis-associated syndromes, while the inhibition of CBP alleviated this process. Overall, our findings highlighted the crucial role of TIR domain complex acetylation in the regulation of inflammatory immune response and suggested that the reversible acetylation of the complex emerged as a promising therapeutic target for M1 macrophages during the progression of sepsis.
Project description:Tumor-associated macrophages contribute to tumor pathogenesis and represent an attractive therapeutic target. We report that the proprotein convertase PC1/3 inhibits the TLR4 Myd88-pathway induced in macrophages by the anti-cancer agent Taxol. Thus, PC1/3 knock-down in these cells exacerbates the TLR4 MyD88-dependent pathway triggered by Taxol. In PC1/3 knock-down macrophages, Taxol drives the secretion of pro-inflammatory cytokines, inhibits STAT3 signaling and counteracts tumor-supportive activities, thus inhibiting viability, growth and invasion of glioblastoma cells. Proteomic analyses indicate that their secretomes are characterized by a unique protein profile supporting a specific paracrine anti-tumoral effect. These findings unravel the potential value of a new therapeutic strategy combining PC1/3 inhibition and activation of the TLR4 MyD88-dependent pathway to switch intra-tumoral macrophages toward an anti-tumoral immunophenotype.
Project description:MyD88-independent signal transduction associated with Toll-like receptors (TLRs) 3 and TLR4 is mediated through the adapter protein TRIF (TIR-domain-containing adapter-inducing interferon-beta). It has been proposed that TLR signalling is important for the transcription of crucial inflammasome components like NLRP3, a process that has been termed "priming". In order to test whether TRIF signalling was required for the priming of inflammasome components, we performed a genome wide transcriptional analysis on wild-type and Trif-knockout bone marrow derived macrophages (BMMs) before and 1, 3 and 6 hours after phagocytosis of E. coli. These results indicated that TRIF was involved in the activation and not transcriptional priming of the NLRP3 inflammasome. Bone marrow derived macrophages from WT and Trif knockout mice, stimulated with E.coli for up to 6hrs.
Project description:In sepsis, acute lung injury (ALI) is a severe complication and a leading cause of death, involving complex mechanisms that include cellular and molecular interactions between immune and lung parenchymal cells. In recent decades, the role of Toll-like receptor 4 (TLR4) in mediating infection-induced inflammation has been extensively studied. However, how TLR4 facilitates interactions between innate immune cells and lung parenchymal cells in sepsis remains to be fully understood. This study aims to explore the role of TLR4 in regulating macrophage immunity and metabolism in greater depth. It also seeks to reveal how changes in these processes affect the interaction between macrophages and both pulmonary endothelial cells (ECs) and lymphatic endothelial cells (LECs). Using TLR4 knockout mice and the combined approaches of single-cell RNA sequencing and experimental validation, we demonstrate that in sepsis, TLR4-deficient macrophages upregulate Abca1, enhance cholesterol efflux, and reduce glycolysis, promoting M2 polarization and attenuating inflammation. These metabolic and phenotypic shifts significantly affect their interactions with pulmonary ECs and LECs. Mechanistically, we uncovered that TLR4 operates through multiple pathways in endothelial dysfunction: macrophage TLR4 mediates inflammatory damage to ECs/LECs, while endothelial TLR4 both directly sensitizes cells to lipopolysaccharide-induced injury and determines their susceptibility to macrophage-derived inflammatory signals. These findings reveal the complex role of TLR4 in orchestrating both immune-mediated and direct endothelial responses during sepsis-induced ALI, supporting that targeting TLR4 on multiple cell populations may present an effective therapeutic strategy.
Project description:We here identified that the trimeric spike protein of SARS-CoV-2 could bind to TLR4 directly and robustly activate downstream signaling in monocytes and neutrophils. Moreover, specific TLR4 or NFKB inhibitor, or knockout of MyD88 could significantly block IL-1B induction by spike protein. We thus reveal that spike protein of SARS-CoV-2 functions as a potent stimulus causing TLR4 activation and sepsis related abnormal responses.
Project description:WT control or MyD88 deficient bone marrow derived macrophages were stimulated with TLR2, TLR3, TLR4, TLR7, and TLR9 ligands for 48 h.
Project description:MyD88-independent signal transduction associated with Toll-like receptors (TLRs) 3 and TLR4 is mediated through the adapter protein TRIF (TIR-domain-containing adapter-inducing interferon-beta). It has been proposed that TLR signalling is important for the transcription of crucial inflammasome components like NLRP3, a process that has been termed "priming". In order to test whether TRIF signalling was required for the priming of inflammasome components, we performed a genome wide transcriptional analysis on wild-type and Trif-knockout bone marrow derived macrophages (BMMs) before and 1, 3 and 6 hours after phagocytosis of E. coli. These results indicated that TRIF was involved in the activation and not transcriptional priming of the NLRP3 inflammasome.