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The ROS scavenger, NAC, regulates hepatic Vα14iNKT cells signaling during Fas mAb-dependent fulminant liver failure.

Downs I, Liu J, Aw TY, Adegboyega PA, Ajuebor MN - PLoS ONE (2012)

Bottom Line: In addition, enrichment of the liver with GSH due to Vα14iNKT cells deficiency, induced an anti-inflammatory response in the liver of Jα18(-/-) mice that inhibited apoptosis, nitrotyrosine formation, IFN-γ signaling and effector functions.In summary, we propose a novel and previously unrecognized pro-inflammatory and pro-apoptotic role for endogenous ROS in stimulating Th1 signaling in Vα14iNKT cells to promote the development of FLF.Therefore, our study provides critical new insights into how NAC, a ROS scavenger, regulates Th1 signaling in intrahepatic Vα14iNKT cells to impact inflammatory and pathological responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana, United States of America.

ABSTRACT
Uncontrolled systemic activation of the immune system is an early initiating event that leads to development of acute fulminant liver failure (FLF) in mice after treatment with agonistic Fas mAb. In this study, we demonstrate that treatment of mice with N-acetylcysteine (NAC), an ROS scavenger and glutathione (GSH) precursor, almost completely abolished Fas mAb-induced FLF through suppression of Vα14iNKT cell activation, IFN-γ signaling, apoptosis and nitrotyrosine formation in liver. In addition, enrichment of the liver with GSH due to Vα14iNKT cells deficiency, induced an anti-inflammatory response in the liver of Jα18(-/-) mice that inhibited apoptosis, nitrotyrosine formation, IFN-γ signaling and effector functions. In summary, we propose a novel and previously unrecognized pro-inflammatory and pro-apoptotic role for endogenous ROS in stimulating Th1 signaling in Vα14iNKT cells to promote the development of FLF. Therefore, our study provides critical new insights into how NAC, a ROS scavenger, regulates Th1 signaling in intrahepatic Vα14iNKT cells to impact inflammatory and pathological responses.

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Effect of NAC treatment on intrahepatic Vα14iNKT cell activation during agonistic Fas mAb-induced FLF.Representative FACS histograms of extracellular CD25 (a), intracellular IFN-γ (d), intracellular TNF-α (e; αGalcer used as a positive control) and intracellular active caspase 3 (f; Adenovirus used as a positive control) expression levels by intrahepatic Vα14iNKT cells at 4.5 h after PBS or agonistic Fas mAb treatment. All experiments were performed twice. Figure S1 in b and c are presented as mean ± s.e.m with n = 4 mice/group; *P<0.05 by one-way analysis of variance followed by Newman-Kuels post hoc test.
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pone-0038051-g002: Effect of NAC treatment on intrahepatic Vα14iNKT cell activation during agonistic Fas mAb-induced FLF.Representative FACS histograms of extracellular CD25 (a), intracellular IFN-γ (d), intracellular TNF-α (e; αGalcer used as a positive control) and intracellular active caspase 3 (f; Adenovirus used as a positive control) expression levels by intrahepatic Vα14iNKT cells at 4.5 h after PBS or agonistic Fas mAb treatment. All experiments were performed twice. Figure S1 in b and c are presented as mean ± s.e.m with n = 4 mice/group; *P<0.05 by one-way analysis of variance followed by Newman-Kuels post hoc test.

Mentions: We next verified by flow cytometry that hepatic Vα14iNKT cells were activated following agonistic Fas mAb administration in WT mice as denoted by upregulation of the activation marker, CD25, on cell surface (Figure 2A and B) and by increased intracellular IFN-γ expression by hepatic Vα14iNKT cells (Figure 2C and D). In addition, we established that the ROS scavenger, NAC, effectively suppressed hepatic Vα14iNKT cells CD25 and IFN-γ expression in WT mice during Fas mAb-mediated FLF (Figure 2A, B, C, D). Although CD25 expression by hepatic Vα14iNKT cells in NAC-treated WT mice during Fas mAb-mediated FLF was 2-fold higher than PBS control, it was not significant (Figure 2B). In contrast, hepatic Vα14iNKT cells IFN-γ expression in NAC-treated WT mice during Fas mAb-mediated FLF was significantly higher (i.e. 3-fold) than PBS control (Figure 2C). Moreover, the number of CD25-positive cells but not IFN-γ positive cells in the liver of WT mice after NAC/Fas mAb treatment was significantly higher than PBS control (Figure S1). It is noteworthy that Vα14iNKT cells from the liver of Fas mAb-treated WT mice lack intracellular TNF-α (Figure 2E) and active caspase 3 (Figure 2F).


The ROS scavenger, NAC, regulates hepatic Vα14iNKT cells signaling during Fas mAb-dependent fulminant liver failure.

Downs I, Liu J, Aw TY, Adegboyega PA, Ajuebor MN - PLoS ONE (2012)

Effect of NAC treatment on intrahepatic Vα14iNKT cell activation during agonistic Fas mAb-induced FLF.Representative FACS histograms of extracellular CD25 (a), intracellular IFN-γ (d), intracellular TNF-α (e; αGalcer used as a positive control) and intracellular active caspase 3 (f; Adenovirus used as a positive control) expression levels by intrahepatic Vα14iNKT cells at 4.5 h after PBS or agonistic Fas mAb treatment. All experiments were performed twice. Figure S1 in b and c are presented as mean ± s.e.m with n = 4 mice/group; *P<0.05 by one-way analysis of variance followed by Newman-Kuels post hoc test.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3368940&req=5

pone-0038051-g002: Effect of NAC treatment on intrahepatic Vα14iNKT cell activation during agonistic Fas mAb-induced FLF.Representative FACS histograms of extracellular CD25 (a), intracellular IFN-γ (d), intracellular TNF-α (e; αGalcer used as a positive control) and intracellular active caspase 3 (f; Adenovirus used as a positive control) expression levels by intrahepatic Vα14iNKT cells at 4.5 h after PBS or agonistic Fas mAb treatment. All experiments were performed twice. Figure S1 in b and c are presented as mean ± s.e.m with n = 4 mice/group; *P<0.05 by one-way analysis of variance followed by Newman-Kuels post hoc test.
Mentions: We next verified by flow cytometry that hepatic Vα14iNKT cells were activated following agonistic Fas mAb administration in WT mice as denoted by upregulation of the activation marker, CD25, on cell surface (Figure 2A and B) and by increased intracellular IFN-γ expression by hepatic Vα14iNKT cells (Figure 2C and D). In addition, we established that the ROS scavenger, NAC, effectively suppressed hepatic Vα14iNKT cells CD25 and IFN-γ expression in WT mice during Fas mAb-mediated FLF (Figure 2A, B, C, D). Although CD25 expression by hepatic Vα14iNKT cells in NAC-treated WT mice during Fas mAb-mediated FLF was 2-fold higher than PBS control, it was not significant (Figure 2B). In contrast, hepatic Vα14iNKT cells IFN-γ expression in NAC-treated WT mice during Fas mAb-mediated FLF was significantly higher (i.e. 3-fold) than PBS control (Figure 2C). Moreover, the number of CD25-positive cells but not IFN-γ positive cells in the liver of WT mice after NAC/Fas mAb treatment was significantly higher than PBS control (Figure S1). It is noteworthy that Vα14iNKT cells from the liver of Fas mAb-treated WT mice lack intracellular TNF-α (Figure 2E) and active caspase 3 (Figure 2F).

Bottom Line: In addition, enrichment of the liver with GSH due to Vα14iNKT cells deficiency, induced an anti-inflammatory response in the liver of Jα18(-/-) mice that inhibited apoptosis, nitrotyrosine formation, IFN-γ signaling and effector functions.In summary, we propose a novel and previously unrecognized pro-inflammatory and pro-apoptotic role for endogenous ROS in stimulating Th1 signaling in Vα14iNKT cells to promote the development of FLF.Therefore, our study provides critical new insights into how NAC, a ROS scavenger, regulates Th1 signaling in intrahepatic Vα14iNKT cells to impact inflammatory and pathological responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana, United States of America.

ABSTRACT
Uncontrolled systemic activation of the immune system is an early initiating event that leads to development of acute fulminant liver failure (FLF) in mice after treatment with agonistic Fas mAb. In this study, we demonstrate that treatment of mice with N-acetylcysteine (NAC), an ROS scavenger and glutathione (GSH) precursor, almost completely abolished Fas mAb-induced FLF through suppression of Vα14iNKT cell activation, IFN-γ signaling, apoptosis and nitrotyrosine formation in liver. In addition, enrichment of the liver with GSH due to Vα14iNKT cells deficiency, induced an anti-inflammatory response in the liver of Jα18(-/-) mice that inhibited apoptosis, nitrotyrosine formation, IFN-γ signaling and effector functions. In summary, we propose a novel and previously unrecognized pro-inflammatory and pro-apoptotic role for endogenous ROS in stimulating Th1 signaling in Vα14iNKT cells to promote the development of FLF. Therefore, our study provides critical new insights into how NAC, a ROS scavenger, regulates Th1 signaling in intrahepatic Vα14iNKT cells to impact inflammatory and pathological responses.

Show MeSH
Related in: MedlinePlus