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Attenuation of the macrophage inflammatory activity by TiO₂ nanotubes via inhibition of MAPK and NF-κB pathways.

Neacsu P, Mazare A, Schmuki P, Cimpean A - Int J Nanomedicine (2015)

Bottom Line: Results showed that the Ti/TiO2 significantly reduce the expression levels of the phosphorylated forms of p38, ERK1/2, c-Jun NH2-terminal kinase (JNK), IKKβ, and IkB-α.Furthermore, a significant reduction in the p65 nuclear accumulation on the nanotubular surface was remarked.However, the selective inhibitor for JNK signaling pathway (SP600125) was effective in reducing tumor necrosis factor alpha release as well as monocyte chemotactic protein-1 and nitric oxide production.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, University of Bucharest, Bucharest, Romania.

ABSTRACT
Biomaterial implantation in a living tissue triggers the activation of macrophages in inflammatory events, promoting the transcription of pro-inflammatory mediator genes. The initiation of macrophage inflammatory processes is mainly regulated by signaling proteins of mitogen-activated protein kinase (MAPK) and by nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways. We have previously shown that titania nanotubes modified Ti surfaces (Ti/TiO2) mitigate the immune response, compared with flat Ti surfaces; however, little is known regarding the underlying mechanism. Therefore, the aim of this study is to investigate the mechanism(s) by which this nanotopography attenuates the inflammatory activity of macrophages. Thus, we analyzed the effects of TiO2 nanotubes on the activation of MAPK and NF-κB signaling pathways in standard and lipopolysaccharide-evoked conditions. Results showed that the Ti/TiO2 significantly reduce the expression levels of the phosphorylated forms of p38, ERK1/2, c-Jun NH2-terminal kinase (JNK), IKKβ, and IkB-α. Furthermore, a significant reduction in the p65 nuclear accumulation on the nanotubular surface was remarked. Following, by using specific MAPK inhibitors, we observed that lipopolysaccharide-induced production of monocyte chemotactic protein-1 and nitric oxide was significantly inhibited on the Ti/TiO2 surface via p38 and ERK1/2, but not via JNK. However, the selective inhibitor for JNK signaling pathway (SP600125) was effective in reducing tumor necrosis factor alpha release as well as monocyte chemotactic protein-1 and nitric oxide production. Altogether, these data suggest that titania nanotubes can attenuate the macrophage inflammatory response via suppression of MAPK and NF-κB pathways providing a potential mechanism for their anti-inflammatory activity.

No MeSH data available.


Related in: MedlinePlus

A schematic diagram showing the proposed mechanisms underlying the attenuation of the macrophage inflammatory response by TiO2 nanotubes.Notes: Nanotubular TiO2 surface acts through significant suppression of LPS-induced NF-κB activation, an event correlated with its inhibitory effect on LPS-induced IkB kinase (IKK) activation, IkB-α phosphorylation (by IKKβ and, possibly, MAPKs), nuclear translocation of p65-NF-κB, and also through suppression of MAPK (ERK, p38, and JNK) phosphorylation. Solid arrows indicate the main inflammatory pathways activated by challenging the RAW 264.7 cells with LPS. The oblic dashed arrow indicates the potential involvement of MAPK in the regulation of NF-κB activation. The dotted arrows show the regulation of the pro-inflammatory gene expression. The right side vertical solid arrows denote the down-regulation of pro-inflammatory gene expression and protein secretion. The right side dashed arrow indicates the direct relationship between the level of protein secretion and that of gene expression. The blunt lines (┣) indicate the inhibition by Ti/TiO2 surfaces. The oval dashed line illustrates the degradation of the phosphorylated IkB-alpha. Yellow “P” symbol denotes the phosphorylated biomolecules.Abbreviations: ERK, extracellular signal-regulated kinase; JNK, c-Jun NH2-terminal kinase; LPS, lipopolysaccharide; MAPK, mitogen-activated protein kinase; NF-κB, nuclear factor kappa-light-chain-enhancer of activated B cells.
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f6-ijn-10-6455: A schematic diagram showing the proposed mechanisms underlying the attenuation of the macrophage inflammatory response by TiO2 nanotubes.Notes: Nanotubular TiO2 surface acts through significant suppression of LPS-induced NF-κB activation, an event correlated with its inhibitory effect on LPS-induced IkB kinase (IKK) activation, IkB-α phosphorylation (by IKKβ and, possibly, MAPKs), nuclear translocation of p65-NF-κB, and also through suppression of MAPK (ERK, p38, and JNK) phosphorylation. Solid arrows indicate the main inflammatory pathways activated by challenging the RAW 264.7 cells with LPS. The oblic dashed arrow indicates the potential involvement of MAPK in the regulation of NF-κB activation. The dotted arrows show the regulation of the pro-inflammatory gene expression. The right side vertical solid arrows denote the down-regulation of pro-inflammatory gene expression and protein secretion. The right side dashed arrow indicates the direct relationship between the level of protein secretion and that of gene expression. The blunt lines (┣) indicate the inhibition by Ti/TiO2 surfaces. The oval dashed line illustrates the degradation of the phosphorylated IkB-alpha. Yellow “P” symbol denotes the phosphorylated biomolecules.Abbreviations: ERK, extracellular signal-regulated kinase; JNK, c-Jun NH2-terminal kinase; LPS, lipopolysaccharide; MAPK, mitogen-activated protein kinase; NF-κB, nuclear factor kappa-light-chain-enhancer of activated B cells.

Mentions: In addition, many independent studies have shown that the MAPK pathways are involved in the upregulation of LPS-induced pro-inflammatory mediators.7,13–15,17,26,51–56 To establish the level of implication of these signaling pathways in reducing the macrophage activation by nanotubular structure, the effect of selective MAPK inhibitors on the secretion of TNF-α, MCP-1, and NO was investigated. Upon treatment of RAW 264.7 cells with LPS and the ERK1/2 and p38 inhibitors, the production of all three analyzed proinflammatory mediators was significantly reduced, while the JNK inhibitor (SP600125) significantly suppressed only the TNF-α production. These results indicate that titania nanotubes exert protective effects against inflammation, through their downregulating effects on the production of MCP-1, NO, and TNF-α, by regulating ERK/p38 and ERK/p38/JNK pathways, respectively. Furthermore, the immuno-suppressive effects of TiO2 nanotubes might be associated with the inactivation of NF-κB signaling pathway as a result of the decrease in IKKβ and IkB-α phosphorylation and subsequent inhibition of the NF-κB-p65 nuclear translocation (Figure 6). Moreover, some studies indicate that the NF-κB transcription factor plays an important part in the regulation of genes encoding the pro-inflammatory cytokines, adhesion molecules, chemokines, growth factors, and inflammation-associated enzymes.9,57–60


Attenuation of the macrophage inflammatory activity by TiO₂ nanotubes via inhibition of MAPK and NF-κB pathways.

Neacsu P, Mazare A, Schmuki P, Cimpean A - Int J Nanomedicine (2015)

A schematic diagram showing the proposed mechanisms underlying the attenuation of the macrophage inflammatory response by TiO2 nanotubes.Notes: Nanotubular TiO2 surface acts through significant suppression of LPS-induced NF-κB activation, an event correlated with its inhibitory effect on LPS-induced IkB kinase (IKK) activation, IkB-α phosphorylation (by IKKβ and, possibly, MAPKs), nuclear translocation of p65-NF-κB, and also through suppression of MAPK (ERK, p38, and JNK) phosphorylation. Solid arrows indicate the main inflammatory pathways activated by challenging the RAW 264.7 cells with LPS. The oblic dashed arrow indicates the potential involvement of MAPK in the regulation of NF-κB activation. The dotted arrows show the regulation of the pro-inflammatory gene expression. The right side vertical solid arrows denote the down-regulation of pro-inflammatory gene expression and protein secretion. The right side dashed arrow indicates the direct relationship between the level of protein secretion and that of gene expression. The blunt lines (┣) indicate the inhibition by Ti/TiO2 surfaces. The oval dashed line illustrates the degradation of the phosphorylated IkB-alpha. Yellow “P” symbol denotes the phosphorylated biomolecules.Abbreviations: ERK, extracellular signal-regulated kinase; JNK, c-Jun NH2-terminal kinase; LPS, lipopolysaccharide; MAPK, mitogen-activated protein kinase; NF-κB, nuclear factor kappa-light-chain-enhancer of activated B cells.
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Related In: Results  -  Collection

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f6-ijn-10-6455: A schematic diagram showing the proposed mechanisms underlying the attenuation of the macrophage inflammatory response by TiO2 nanotubes.Notes: Nanotubular TiO2 surface acts through significant suppression of LPS-induced NF-κB activation, an event correlated with its inhibitory effect on LPS-induced IkB kinase (IKK) activation, IkB-α phosphorylation (by IKKβ and, possibly, MAPKs), nuclear translocation of p65-NF-κB, and also through suppression of MAPK (ERK, p38, and JNK) phosphorylation. Solid arrows indicate the main inflammatory pathways activated by challenging the RAW 264.7 cells with LPS. The oblic dashed arrow indicates the potential involvement of MAPK in the regulation of NF-κB activation. The dotted arrows show the regulation of the pro-inflammatory gene expression. The right side vertical solid arrows denote the down-regulation of pro-inflammatory gene expression and protein secretion. The right side dashed arrow indicates the direct relationship between the level of protein secretion and that of gene expression. The blunt lines (┣) indicate the inhibition by Ti/TiO2 surfaces. The oval dashed line illustrates the degradation of the phosphorylated IkB-alpha. Yellow “P” symbol denotes the phosphorylated biomolecules.Abbreviations: ERK, extracellular signal-regulated kinase; JNK, c-Jun NH2-terminal kinase; LPS, lipopolysaccharide; MAPK, mitogen-activated protein kinase; NF-κB, nuclear factor kappa-light-chain-enhancer of activated B cells.
Mentions: In addition, many independent studies have shown that the MAPK pathways are involved in the upregulation of LPS-induced pro-inflammatory mediators.7,13–15,17,26,51–56 To establish the level of implication of these signaling pathways in reducing the macrophage activation by nanotubular structure, the effect of selective MAPK inhibitors on the secretion of TNF-α, MCP-1, and NO was investigated. Upon treatment of RAW 264.7 cells with LPS and the ERK1/2 and p38 inhibitors, the production of all three analyzed proinflammatory mediators was significantly reduced, while the JNK inhibitor (SP600125) significantly suppressed only the TNF-α production. These results indicate that titania nanotubes exert protective effects against inflammation, through their downregulating effects on the production of MCP-1, NO, and TNF-α, by regulating ERK/p38 and ERK/p38/JNK pathways, respectively. Furthermore, the immuno-suppressive effects of TiO2 nanotubes might be associated with the inactivation of NF-κB signaling pathway as a result of the decrease in IKKβ and IkB-α phosphorylation and subsequent inhibition of the NF-κB-p65 nuclear translocation (Figure 6). Moreover, some studies indicate that the NF-κB transcription factor plays an important part in the regulation of genes encoding the pro-inflammatory cytokines, adhesion molecules, chemokines, growth factors, and inflammation-associated enzymes.9,57–60

Bottom Line: Results showed that the Ti/TiO2 significantly reduce the expression levels of the phosphorylated forms of p38, ERK1/2, c-Jun NH2-terminal kinase (JNK), IKKβ, and IkB-α.Furthermore, a significant reduction in the p65 nuclear accumulation on the nanotubular surface was remarked.However, the selective inhibitor for JNK signaling pathway (SP600125) was effective in reducing tumor necrosis factor alpha release as well as monocyte chemotactic protein-1 and nitric oxide production.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, University of Bucharest, Bucharest, Romania.

ABSTRACT
Biomaterial implantation in a living tissue triggers the activation of macrophages in inflammatory events, promoting the transcription of pro-inflammatory mediator genes. The initiation of macrophage inflammatory processes is mainly regulated by signaling proteins of mitogen-activated protein kinase (MAPK) and by nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways. We have previously shown that titania nanotubes modified Ti surfaces (Ti/TiO2) mitigate the immune response, compared with flat Ti surfaces; however, little is known regarding the underlying mechanism. Therefore, the aim of this study is to investigate the mechanism(s) by which this nanotopography attenuates the inflammatory activity of macrophages. Thus, we analyzed the effects of TiO2 nanotubes on the activation of MAPK and NF-κB signaling pathways in standard and lipopolysaccharide-evoked conditions. Results showed that the Ti/TiO2 significantly reduce the expression levels of the phosphorylated forms of p38, ERK1/2, c-Jun NH2-terminal kinase (JNK), IKKβ, and IkB-α. Furthermore, a significant reduction in the p65 nuclear accumulation on the nanotubular surface was remarked. Following, by using specific MAPK inhibitors, we observed that lipopolysaccharide-induced production of monocyte chemotactic protein-1 and nitric oxide was significantly inhibited on the Ti/TiO2 surface via p38 and ERK1/2, but not via JNK. However, the selective inhibitor for JNK signaling pathway (SP600125) was effective in reducing tumor necrosis factor alpha release as well as monocyte chemotactic protein-1 and nitric oxide production. Altogether, these data suggest that titania nanotubes can attenuate the macrophage inflammatory response via suppression of MAPK and NF-κB pathways providing a potential mechanism for their anti-inflammatory activity.

No MeSH data available.


Related in: MedlinePlus