Limits...
Activation of the NF κ B Pathway Enhances AhR Expression in Intestinal Caco-2 Cells.

Champion S, Sauzet C, Bremond P, Benbrahim K, Abraldes J, Seree E, Barra Y, Villard PH - ISRN Toxicol (2013)

Bottom Line: This was associated with an increase in AhR promoter activity.Similar results were obtained with conditioned media from PMA-treated THP-1 cells.Our results support this hypothesis and suggest that AhR could be a new target for inflammatory bowel disease patient management.

View Article: PubMed Central - PubMed

Affiliation: IMBE-UMR CNRS 7263, IRD 237 Aix-Marseille Université Campus Timone, Faculté de Pharmacie, 27 boulevard Jean Moulin, 13385 Marseille Cedex 05, France.

ABSTRACT
Recent data suggest that apart from its well-known role in the regulation of xenobiotic metabolizing enzymes, AhR is also involved in inflammation. However, the influence of inflammation on AhR expression remains unknown. Here, we demonstrated that proinflammatory conditions induced by either PMA or IL-1 β enhance AhR expression in Caco-2 cells. This was associated with an increase in AhR promoter activity. By means of directed mutagenesis experiments and the use of proteasome inhibitors, we demonstrated that inflammation-induced AhR expression involved the NF κ B pathway but not AP-1. Moreover, conditioned media from PMA-treated Caco-2 cells were also able to induce AhR expression, and this induction was repressed by anti-IL-1 β blocking antibodies. Similar results were obtained with conditioned media from PMA-treated THP-1 cells. Taken together, these data suggest that AhR could be involved in vivo in an inflammatory loop. AhR was recently suspected to be implicated in inflammatory bowel disease. Our results support this hypothesis and suggest that AhR could be a new target for inflammatory bowel disease patient management.

No MeSH data available.


Related in: MedlinePlus

Effect of 8 h exposure to conditioned media from 100 nM PMA-treated Caco-2 cells on AhR mRNA levels (a). Effect of 8 h exposure to conditioned media from 100 nM PMA 24 h treated Caco-2 cells in presence of IL-1β-neutralizing antibodies on AhR mRNA levels (b). Effect of 8 h exposure to conditioned media from 100 nM PMA-treated THP-1 cells on AhR mRNA levels (c). *: P < 0.05 versus control.
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3818893&req=5

fig5: Effect of 8 h exposure to conditioned media from 100 nM PMA-treated Caco-2 cells on AhR mRNA levels (a). Effect of 8 h exposure to conditioned media from 100 nM PMA 24 h treated Caco-2 cells in presence of IL-1β-neutralizing antibodies on AhR mRNA levels (b). Effect of 8 h exposure to conditioned media from 100 nM PMA-treated THP-1 cells on AhR mRNA levels (c). *: P < 0.05 versus control.

Mentions: Caco-2 cells are able to produce cytokines, notably TNFα and IL-1β, in response to proinflammatory signals [15]. These cytokines exert their effect through the NFκB pathway. Therefore, treating Caco-2 cells with conditioned media from PMA-treated Caco-2 cells should result in AhR induction. Our results are summarized in Figure 5. Media collected from 6 to 24 h after treating Caco-2 cells with PMA significantly upregulated AhR mRNA. Maximal activity (4.2-fold increase) was obtained with the 24 h conditioned medium (Figure 5(a)). Pretreating the cells with an IL-1β neutralizing antibody (dilution 1/100) 4 h before exposure to 24 h PMA-conditioned medium inhibited the induction of AhR expression, while pretreatment with rabbit isotype IgG had no effect (Figure 5(b)). In another experiment, Caco-2 cells were treated with conditioned media from PMA-treated THP-1 cells, and similarly we observed an induction of AhR mRNA (4.4-fold increase) (Figure 5(c)). Our data therefore point to the involvement of a signalization loop which could lead to an enhancement of inflammatory processes.


Activation of the NF κ B Pathway Enhances AhR Expression in Intestinal Caco-2 Cells.

Champion S, Sauzet C, Bremond P, Benbrahim K, Abraldes J, Seree E, Barra Y, Villard PH - ISRN Toxicol (2013)

Effect of 8 h exposure to conditioned media from 100 nM PMA-treated Caco-2 cells on AhR mRNA levels (a). Effect of 8 h exposure to conditioned media from 100 nM PMA 24 h treated Caco-2 cells in presence of IL-1β-neutralizing antibodies on AhR mRNA levels (b). Effect of 8 h exposure to conditioned media from 100 nM PMA-treated THP-1 cells on AhR mRNA levels (c). *: P < 0.05 versus control.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3818893&req=5

fig5: Effect of 8 h exposure to conditioned media from 100 nM PMA-treated Caco-2 cells on AhR mRNA levels (a). Effect of 8 h exposure to conditioned media from 100 nM PMA 24 h treated Caco-2 cells in presence of IL-1β-neutralizing antibodies on AhR mRNA levels (b). Effect of 8 h exposure to conditioned media from 100 nM PMA-treated THP-1 cells on AhR mRNA levels (c). *: P < 0.05 versus control.
Mentions: Caco-2 cells are able to produce cytokines, notably TNFα and IL-1β, in response to proinflammatory signals [15]. These cytokines exert their effect through the NFκB pathway. Therefore, treating Caco-2 cells with conditioned media from PMA-treated Caco-2 cells should result in AhR induction. Our results are summarized in Figure 5. Media collected from 6 to 24 h after treating Caco-2 cells with PMA significantly upregulated AhR mRNA. Maximal activity (4.2-fold increase) was obtained with the 24 h conditioned medium (Figure 5(a)). Pretreating the cells with an IL-1β neutralizing antibody (dilution 1/100) 4 h before exposure to 24 h PMA-conditioned medium inhibited the induction of AhR expression, while pretreatment with rabbit isotype IgG had no effect (Figure 5(b)). In another experiment, Caco-2 cells were treated with conditioned media from PMA-treated THP-1 cells, and similarly we observed an induction of AhR mRNA (4.4-fold increase) (Figure 5(c)). Our data therefore point to the involvement of a signalization loop which could lead to an enhancement of inflammatory processes.

Bottom Line: This was associated with an increase in AhR promoter activity.Similar results were obtained with conditioned media from PMA-treated THP-1 cells.Our results support this hypothesis and suggest that AhR could be a new target for inflammatory bowel disease patient management.

View Article: PubMed Central - PubMed

Affiliation: IMBE-UMR CNRS 7263, IRD 237 Aix-Marseille Université Campus Timone, Faculté de Pharmacie, 27 boulevard Jean Moulin, 13385 Marseille Cedex 05, France.

ABSTRACT
Recent data suggest that apart from its well-known role in the regulation of xenobiotic metabolizing enzymes, AhR is also involved in inflammation. However, the influence of inflammation on AhR expression remains unknown. Here, we demonstrated that proinflammatory conditions induced by either PMA or IL-1 β enhance AhR expression in Caco-2 cells. This was associated with an increase in AhR promoter activity. By means of directed mutagenesis experiments and the use of proteasome inhibitors, we demonstrated that inflammation-induced AhR expression involved the NF κ B pathway but not AP-1. Moreover, conditioned media from PMA-treated Caco-2 cells were also able to induce AhR expression, and this induction was repressed by anti-IL-1 β blocking antibodies. Similar results were obtained with conditioned media from PMA-treated THP-1 cells. Taken together, these data suggest that AhR could be involved in vivo in an inflammatory loop. AhR was recently suspected to be implicated in inflammatory bowel disease. Our results support this hypothesis and suggest that AhR could be a new target for inflammatory bowel disease patient management.

No MeSH data available.


Related in: MedlinePlus