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Systemic inhibition of NF-kappaB activation protects from silicosis.

Di Giuseppe M, Gambelli F, Hoyle GW, Lungarella G, Studer SM, Richards T, Yousem S, McCurry K, Dauber J, Kaminski N, Leikauf G, Ortiz LA - PLoS ONE (2009)

Bottom Line: At the time of lung transplantation, we found the lungs of silica-exposed subjects to contain multiple foci of inflammatory cells and silicotic nodules with proximal TNFalpha expressing macrophage and NF-kappaB activation in epithelial cells.Using a mouse experimental model in which the endotracheal instillation of silica reproduces the silica-induced lung injury observed in humans we found that systemic inhibition of NF-kappaB activation with a pharmacologic inhibitor (BAY 11-7085) of IkappaB alpha phosphorylation decreased silica-induced inflammation and collagen deposition.In contrast, transgenic mice expressing a dominant negative IkappaB alpha mutant protein under the control of epithelial cell specific promoters demonstrate enhanced apoptosis and collagen deposition in their lungs in response to silica.

View Article: PubMed Central - PubMed

Affiliation: Division of Occupational and Environmental Medicine, Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.

ABSTRACT

Background: Silicosis is a complex lung disease for which no successful treatment is available and therefore lung transplantation is a potential alternative. Tumor necrosis factor alpha (TNFalpha) plays a central role in the pathogenesis of silicosis. TNFalpha signaling is mediated by the transcription factor, Nuclear Factor (NF)-kappaB, which regulates genes controlling several physiological processes including the innate immune responses, cell death, and inflammation. Therefore, inhibition of NF-kappaB activation represents a potential therapeutic strategy for silicosis.

Methods/findings: In the present work we evaluated the lung transplant database (May 1986-July 2007) at the University of Pittsburgh to study the efficacy of lung transplantation in patients with silicosis (n = 11). We contrasted the overall survival and rate of graft rejection in these patients to that of patients with idiopathic pulmonary fibrosis (IPF, n = 79) that was selected as a control group because survival benefit of lung transplantation has been identified for these patients. At the time of lung transplantation, we found the lungs of silica-exposed subjects to contain multiple foci of inflammatory cells and silicotic nodules with proximal TNFalpha expressing macrophage and NF-kappaB activation in epithelial cells. Patients with silicosis had poor survival (median survival 2.4 yr; confidence interval (CI): 0.16-7.88 yr) compared to IPF patients (5.3 yr; CI: 2.8-15 yr; p = 0.07), and experienced early rejection of their lung grafts (0.9 yr; CI: 0.22-0.9 yr) following lung transplantation (2.4 yr; CI:1.5-3.6 yr; p<0.05). Using a mouse experimental model in which the endotracheal instillation of silica reproduces the silica-induced lung injury observed in humans we found that systemic inhibition of NF-kappaB activation with a pharmacologic inhibitor (BAY 11-7085) of IkappaB alpha phosphorylation decreased silica-induced inflammation and collagen deposition. In contrast, transgenic mice expressing a dominant negative IkappaB alpha mutant protein under the control of epithelial cell specific promoters demonstrate enhanced apoptosis and collagen deposition in their lungs in response to silica.

Conclusions: Although limited by its size, our data support that patients with silicosis appear to have poor outcome following lung transplantation. Experimental data indicate that while the systemic inhibition of NF-kappaB protects from silica-induced lung injury, epithelial cell specific NF-kappaB inhibition appears to aggravate the outcome of experimental silicosis.

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Tumor necrosis factor alpha (TNFα), nuclear factor kappa B (NFKB) and associated cytokines increased in mouse lung following silica treatment.Mice (n = 5 C57BL/6J mice/group) were treated with silica, lung mRNA was obtained at 3, 7, 14, and 28 days, and 40 transcript levels were assessed by qRT-PCR. (A) Self-organizing map visualization of transcripts in Tree View. The order of the transcripts is greatest (top) to lowest (bottom) as measured on day 28. (B) Visualization of Mean Tendency of the 40 transcripts measured. Values are mean±standard error and *p<0.05 as determined by One way analysis of variance with all pairwise multiple comparison procedures (Holm-Sidak method). (C) Transcript levels of selected members of TNFα signaling, NFKB signaling, and downstream cytokine families. All abbreviations are current Entrez Gene official symbols and official full names are presented in Table S1.
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pone-0005689-g003: Tumor necrosis factor alpha (TNFα), nuclear factor kappa B (NFKB) and associated cytokines increased in mouse lung following silica treatment.Mice (n = 5 C57BL/6J mice/group) were treated with silica, lung mRNA was obtained at 3, 7, 14, and 28 days, and 40 transcript levels were assessed by qRT-PCR. (A) Self-organizing map visualization of transcripts in Tree View. The order of the transcripts is greatest (top) to lowest (bottom) as measured on day 28. (B) Visualization of Mean Tendency of the 40 transcripts measured. Values are mean±standard error and *p<0.05 as determined by One way analysis of variance with all pairwise multiple comparison procedures (Holm-Sidak method). (C) Transcript levels of selected members of TNFα signaling, NFKB signaling, and downstream cytokine families. All abbreviations are current Entrez Gene official symbols and official full names are presented in Table S1.

Mentions: To ascertain whether TNFα or NF-κB signaling pathways and targeted cytokines were altered in silica treated mice, 40 lung transcripts were assessed in the lung of C57BL/6 mice at 3, 7, 14 and 28 d after silica exposure. Overall, 26 transcripts increased (p<0.05) within 3 d and were slightly higher than the mean level at 7 d (Figure 3A and Figure 3B). At 28 d, 38 of the 40 transcripts were increased (only CHUK and EGR1 were not significantly increased). Of the 40 transcripts measured, TNFα increased the most (∼90-fold). TNFα receptors, TNFRSF1B and TNFRSF1A, increased, as did transcripts that are rapidly induced by TNFα, TNFAIP3 and RIPK2 (Figure 3C). All 19 TNF signaling pathway transcripts increased by 28 d (Figure 3A). Albeit somewhat less the TNF signaling pathway, NF-κB signaling pathway transcripts also increased in mouse lung following silica exposure. At 28 d, NFKB1 (p50) increased ∼5–10 fold and Rel/NFKB family transcription factors (REL, RELA, RELB) increased ∼5–15 fold (Figure 3C). Only 1 (CHUK) of 9 transcripts in the NF-κB signaling pathway was not significantly different from control by 28 d. In addition, 11 of 12 cytokine transcripts increased significantly with the progression of treatment. Of these, cytokine controlling the production, differentiation, and function of monocytes/macrophages (CCL2 a.k.a. MCP1, and CSF2 a.k.a. GM-CSF), and of granulocytes (CSF2: a.k.a. G-CSF; CCL2) are noteworthy (Figure 3C). In addition, transcripts encoding interleukins (IL1B, IL6), IFNG, and the downstream transcription activator, STAT1, increased markedly (∼8–20 fold at 28 d).


Systemic inhibition of NF-kappaB activation protects from silicosis.

Di Giuseppe M, Gambelli F, Hoyle GW, Lungarella G, Studer SM, Richards T, Yousem S, McCurry K, Dauber J, Kaminski N, Leikauf G, Ortiz LA - PLoS ONE (2009)

Tumor necrosis factor alpha (TNFα), nuclear factor kappa B (NFKB) and associated cytokines increased in mouse lung following silica treatment.Mice (n = 5 C57BL/6J mice/group) were treated with silica, lung mRNA was obtained at 3, 7, 14, and 28 days, and 40 transcript levels were assessed by qRT-PCR. (A) Self-organizing map visualization of transcripts in Tree View. The order of the transcripts is greatest (top) to lowest (bottom) as measured on day 28. (B) Visualization of Mean Tendency of the 40 transcripts measured. Values are mean±standard error and *p<0.05 as determined by One way analysis of variance with all pairwise multiple comparison procedures (Holm-Sidak method). (C) Transcript levels of selected members of TNFα signaling, NFKB signaling, and downstream cytokine families. All abbreviations are current Entrez Gene official symbols and official full names are presented in Table S1.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2682759&req=5

pone-0005689-g003: Tumor necrosis factor alpha (TNFα), nuclear factor kappa B (NFKB) and associated cytokines increased in mouse lung following silica treatment.Mice (n = 5 C57BL/6J mice/group) were treated with silica, lung mRNA was obtained at 3, 7, 14, and 28 days, and 40 transcript levels were assessed by qRT-PCR. (A) Self-organizing map visualization of transcripts in Tree View. The order of the transcripts is greatest (top) to lowest (bottom) as measured on day 28. (B) Visualization of Mean Tendency of the 40 transcripts measured. Values are mean±standard error and *p<0.05 as determined by One way analysis of variance with all pairwise multiple comparison procedures (Holm-Sidak method). (C) Transcript levels of selected members of TNFα signaling, NFKB signaling, and downstream cytokine families. All abbreviations are current Entrez Gene official symbols and official full names are presented in Table S1.
Mentions: To ascertain whether TNFα or NF-κB signaling pathways and targeted cytokines were altered in silica treated mice, 40 lung transcripts were assessed in the lung of C57BL/6 mice at 3, 7, 14 and 28 d after silica exposure. Overall, 26 transcripts increased (p<0.05) within 3 d and were slightly higher than the mean level at 7 d (Figure 3A and Figure 3B). At 28 d, 38 of the 40 transcripts were increased (only CHUK and EGR1 were not significantly increased). Of the 40 transcripts measured, TNFα increased the most (∼90-fold). TNFα receptors, TNFRSF1B and TNFRSF1A, increased, as did transcripts that are rapidly induced by TNFα, TNFAIP3 and RIPK2 (Figure 3C). All 19 TNF signaling pathway transcripts increased by 28 d (Figure 3A). Albeit somewhat less the TNF signaling pathway, NF-κB signaling pathway transcripts also increased in mouse lung following silica exposure. At 28 d, NFKB1 (p50) increased ∼5–10 fold and Rel/NFKB family transcription factors (REL, RELA, RELB) increased ∼5–15 fold (Figure 3C). Only 1 (CHUK) of 9 transcripts in the NF-κB signaling pathway was not significantly different from control by 28 d. In addition, 11 of 12 cytokine transcripts increased significantly with the progression of treatment. Of these, cytokine controlling the production, differentiation, and function of monocytes/macrophages (CCL2 a.k.a. MCP1, and CSF2 a.k.a. GM-CSF), and of granulocytes (CSF2: a.k.a. G-CSF; CCL2) are noteworthy (Figure 3C). In addition, transcripts encoding interleukins (IL1B, IL6), IFNG, and the downstream transcription activator, STAT1, increased markedly (∼8–20 fold at 28 d).

Bottom Line: At the time of lung transplantation, we found the lungs of silica-exposed subjects to contain multiple foci of inflammatory cells and silicotic nodules with proximal TNFalpha expressing macrophage and NF-kappaB activation in epithelial cells.Using a mouse experimental model in which the endotracheal instillation of silica reproduces the silica-induced lung injury observed in humans we found that systemic inhibition of NF-kappaB activation with a pharmacologic inhibitor (BAY 11-7085) of IkappaB alpha phosphorylation decreased silica-induced inflammation and collagen deposition.In contrast, transgenic mice expressing a dominant negative IkappaB alpha mutant protein under the control of epithelial cell specific promoters demonstrate enhanced apoptosis and collagen deposition in their lungs in response to silica.

View Article: PubMed Central - PubMed

Affiliation: Division of Occupational and Environmental Medicine, Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.

ABSTRACT

Background: Silicosis is a complex lung disease for which no successful treatment is available and therefore lung transplantation is a potential alternative. Tumor necrosis factor alpha (TNFalpha) plays a central role in the pathogenesis of silicosis. TNFalpha signaling is mediated by the transcription factor, Nuclear Factor (NF)-kappaB, which regulates genes controlling several physiological processes including the innate immune responses, cell death, and inflammation. Therefore, inhibition of NF-kappaB activation represents a potential therapeutic strategy for silicosis.

Methods/findings: In the present work we evaluated the lung transplant database (May 1986-July 2007) at the University of Pittsburgh to study the efficacy of lung transplantation in patients with silicosis (n = 11). We contrasted the overall survival and rate of graft rejection in these patients to that of patients with idiopathic pulmonary fibrosis (IPF, n = 79) that was selected as a control group because survival benefit of lung transplantation has been identified for these patients. At the time of lung transplantation, we found the lungs of silica-exposed subjects to contain multiple foci of inflammatory cells and silicotic nodules with proximal TNFalpha expressing macrophage and NF-kappaB activation in epithelial cells. Patients with silicosis had poor survival (median survival 2.4 yr; confidence interval (CI): 0.16-7.88 yr) compared to IPF patients (5.3 yr; CI: 2.8-15 yr; p = 0.07), and experienced early rejection of their lung grafts (0.9 yr; CI: 0.22-0.9 yr) following lung transplantation (2.4 yr; CI:1.5-3.6 yr; p<0.05). Using a mouse experimental model in which the endotracheal instillation of silica reproduces the silica-induced lung injury observed in humans we found that systemic inhibition of NF-kappaB activation with a pharmacologic inhibitor (BAY 11-7085) of IkappaB alpha phosphorylation decreased silica-induced inflammation and collagen deposition. In contrast, transgenic mice expressing a dominant negative IkappaB alpha mutant protein under the control of epithelial cell specific promoters demonstrate enhanced apoptosis and collagen deposition in their lungs in response to silica.

Conclusions: Although limited by its size, our data support that patients with silicosis appear to have poor outcome following lung transplantation. Experimental data indicate that while the systemic inhibition of NF-kappaB protects from silica-induced lung injury, epithelial cell specific NF-kappaB inhibition appears to aggravate the outcome of experimental silicosis.

Show MeSH
Related in: MedlinePlus