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IL-10 modulates DSS-induced colitis through a macrophage-ROS-NO axis.

Li B, Alli R, Vogel P, Geiger TL - Mucosal Immunol (2013)

Bottom Line: Lamina propria macrophages (LPMφs) did not show numerical or phenotypic differences from controls, or a competitive advantage over wild-type cells.Proinflammatory cytokine production, and particularly tumor necrosis factor-α (TNF-α), was increased, although TNF-α neutralization failed to reveal a defining role for this cytokine in the aggravated disease.Downregulation of NO and ROS production are central to the protective actions of IL-10.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, St Jude Children's Research Hospital, Memphis, Tennessee, USA.

ABSTRACT
Breakdown of the epithelial barrier because of toxins or other insults leads to severe colitis. Interleukin-10 (IL-10) is a critical regulator of this, yet its cellular targets and mechanisms of action are not resolved. We address this here. Mice with a macrophage-selective deletion of IL-10Rα (IL-10Rα(Mdel)) developed markedly enhanced dextran sodium sulfate (DSS)-induced colitis that did not significantly differ from disease in IL-10(-/-) or IL-10Rα(-/-) mice; no impact of IL-10Rα deficiency in other lineages was observed. IL-10Rα(Mdel) colitis was associated with increased mucosal barrier disruption in the setting of intact epithelial regeneration. Lamina propria macrophages (LPMφs) did not show numerical or phenotypic differences from controls, or a competitive advantage over wild-type cells. Proinflammatory cytokine production, and particularly tumor necrosis factor-α (TNF-α), was increased, although TNF-α neutralization failed to reveal a defining role for this cytokine in the aggravated disease. Rather, IL-10Rα(Mdel) LPMφs produced substantially greater levels of nitric oxide (NO) and reactive oxygen species (ROS) than controls. Inhibition of these had modest effects in wild-type mice, although they dramatically reduced colitis severity in IL-10Rα(Mdel) mice, and largely eliminated the differential effect of DSS in them. Therefore, the palliative actions of IL-10 in DSS-induced colitis predominantly results from its macrophage-specific effects. Downregulation of NO and ROS production are central to the protective actions of IL-10.

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Role of NO and arginase in colitis exacerbation(A) Macrophages were sorted from colons of mice with colitis (d 7) and iNOS and arginase expression were measured by qRT-PCR. The ratio of expression in IL-10RαMdel to IL-10Rαfl/fl was measured. Mean + 1 s.d. is plotted. (B) Colon tissue from mice with colitis (d 7) was homogenized and tissue NOS activity measured using a colorimetric assay. Results from individual mice (circles) and cohort means (lines) are shown. (C) Colitis was induced in IL-10RαMdel and IL-10Rαfl/fl mice with 3% DSS. AG or saline was administered i.p. Mean±1 s.e.m. weight change from d 0 is plotted (n=10/cohort). (D) Rectal bleeding scores measured on d 7 after colitis induction. (E, F) Analyses are similar to (C, D) except IL-10RαMdel and IL-10Rαfl/fl mice (n=10/cohort) were treated with BEC or saline by i.p. injection. *; p < 0.05, **, p < 0.01. For experiments C-F, statistical significance is only shown comparing drug treated and untreated IL-10RαMdel or IL-10Rαfl/fl mice. Significance levels between IL-10RαMdel and IL-10Rαfl/fl cohorts are not shown. Data are representative of two independent experiments.
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Figure 5: Role of NO and arginase in colitis exacerbation(A) Macrophages were sorted from colons of mice with colitis (d 7) and iNOS and arginase expression were measured by qRT-PCR. The ratio of expression in IL-10RαMdel to IL-10Rαfl/fl was measured. Mean + 1 s.d. is plotted. (B) Colon tissue from mice with colitis (d 7) was homogenized and tissue NOS activity measured using a colorimetric assay. Results from individual mice (circles) and cohort means (lines) are shown. (C) Colitis was induced in IL-10RαMdel and IL-10Rαfl/fl mice with 3% DSS. AG or saline was administered i.p. Mean±1 s.e.m. weight change from d 0 is plotted (n=10/cohort). (D) Rectal bleeding scores measured on d 7 after colitis induction. (E, F) Analyses are similar to (C, D) except IL-10RαMdel and IL-10Rαfl/fl mice (n=10/cohort) were treated with BEC or saline by i.p. injection. *; p < 0.05, **, p < 0.01. For experiments C-F, statistical significance is only shown comparing drug treated and untreated IL-10RαMdel or IL-10Rαfl/fl mice. Significance levels between IL-10RαMdel and IL-10Rαfl/fl cohorts are not shown. Data are representative of two independent experiments.

Mentions: IL-10 potently inhibits iNOS, and thereby NO production. The integrated effects of NO’s antimicrobial activity, toxic actions on the barrier, and cell signaling activity may alternatively promote or diminish colitis. In DSS colitis, excessive NO production worsens disease, though protective effects of NO have also been identified26. To assess iNOS activity, we sorted LPMϕs from colitic mice and quantified iNOS mRNA. Levels were 4.7±0.8 fold higher in IL-10RαMdel compared with IL-10Rαfl/fl macrophages. Arginase, which inhibits iNOS by degrading NO’s nitrogen source, was reciprocally though less strongly decreased (0.52±0.07 fold, Fig. 5a).


IL-10 modulates DSS-induced colitis through a macrophage-ROS-NO axis.

Li B, Alli R, Vogel P, Geiger TL - Mucosal Immunol (2013)

Role of NO and arginase in colitis exacerbation(A) Macrophages were sorted from colons of mice with colitis (d 7) and iNOS and arginase expression were measured by qRT-PCR. The ratio of expression in IL-10RαMdel to IL-10Rαfl/fl was measured. Mean + 1 s.d. is plotted. (B) Colon tissue from mice with colitis (d 7) was homogenized and tissue NOS activity measured using a colorimetric assay. Results from individual mice (circles) and cohort means (lines) are shown. (C) Colitis was induced in IL-10RαMdel and IL-10Rαfl/fl mice with 3% DSS. AG or saline was administered i.p. Mean±1 s.e.m. weight change from d 0 is plotted (n=10/cohort). (D) Rectal bleeding scores measured on d 7 after colitis induction. (E, F) Analyses are similar to (C, D) except IL-10RαMdel and IL-10Rαfl/fl mice (n=10/cohort) were treated with BEC or saline by i.p. injection. *; p < 0.05, **, p < 0.01. For experiments C-F, statistical significance is only shown comparing drug treated and untreated IL-10RαMdel or IL-10Rαfl/fl mice. Significance levels between IL-10RαMdel and IL-10Rαfl/fl cohorts are not shown. Data are representative of two independent experiments.
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Related In: Results  -  Collection

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Figure 5: Role of NO and arginase in colitis exacerbation(A) Macrophages were sorted from colons of mice with colitis (d 7) and iNOS and arginase expression were measured by qRT-PCR. The ratio of expression in IL-10RαMdel to IL-10Rαfl/fl was measured. Mean + 1 s.d. is plotted. (B) Colon tissue from mice with colitis (d 7) was homogenized and tissue NOS activity measured using a colorimetric assay. Results from individual mice (circles) and cohort means (lines) are shown. (C) Colitis was induced in IL-10RαMdel and IL-10Rαfl/fl mice with 3% DSS. AG or saline was administered i.p. Mean±1 s.e.m. weight change from d 0 is plotted (n=10/cohort). (D) Rectal bleeding scores measured on d 7 after colitis induction. (E, F) Analyses are similar to (C, D) except IL-10RαMdel and IL-10Rαfl/fl mice (n=10/cohort) were treated with BEC or saline by i.p. injection. *; p < 0.05, **, p < 0.01. For experiments C-F, statistical significance is only shown comparing drug treated and untreated IL-10RαMdel or IL-10Rαfl/fl mice. Significance levels between IL-10RαMdel and IL-10Rαfl/fl cohorts are not shown. Data are representative of two independent experiments.
Mentions: IL-10 potently inhibits iNOS, and thereby NO production. The integrated effects of NO’s antimicrobial activity, toxic actions on the barrier, and cell signaling activity may alternatively promote or diminish colitis. In DSS colitis, excessive NO production worsens disease, though protective effects of NO have also been identified26. To assess iNOS activity, we sorted LPMϕs from colitic mice and quantified iNOS mRNA. Levels were 4.7±0.8 fold higher in IL-10RαMdel compared with IL-10Rαfl/fl macrophages. Arginase, which inhibits iNOS by degrading NO’s nitrogen source, was reciprocally though less strongly decreased (0.52±0.07 fold, Fig. 5a).

Bottom Line: Lamina propria macrophages (LPMφs) did not show numerical or phenotypic differences from controls, or a competitive advantage over wild-type cells.Proinflammatory cytokine production, and particularly tumor necrosis factor-α (TNF-α), was increased, although TNF-α neutralization failed to reveal a defining role for this cytokine in the aggravated disease.Downregulation of NO and ROS production are central to the protective actions of IL-10.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, St Jude Children's Research Hospital, Memphis, Tennessee, USA.

ABSTRACT
Breakdown of the epithelial barrier because of toxins or other insults leads to severe colitis. Interleukin-10 (IL-10) is a critical regulator of this, yet its cellular targets and mechanisms of action are not resolved. We address this here. Mice with a macrophage-selective deletion of IL-10Rα (IL-10Rα(Mdel)) developed markedly enhanced dextran sodium sulfate (DSS)-induced colitis that did not significantly differ from disease in IL-10(-/-) or IL-10Rα(-/-) mice; no impact of IL-10Rα deficiency in other lineages was observed. IL-10Rα(Mdel) colitis was associated with increased mucosal barrier disruption in the setting of intact epithelial regeneration. Lamina propria macrophages (LPMφs) did not show numerical or phenotypic differences from controls, or a competitive advantage over wild-type cells. Proinflammatory cytokine production, and particularly tumor necrosis factor-α (TNF-α), was increased, although TNF-α neutralization failed to reveal a defining role for this cytokine in the aggravated disease. Rather, IL-10Rα(Mdel) LPMφs produced substantially greater levels of nitric oxide (NO) and reactive oxygen species (ROS) than controls. Inhibition of these had modest effects in wild-type mice, although they dramatically reduced colitis severity in IL-10Rα(Mdel) mice, and largely eliminated the differential effect of DSS in them. Therefore, the palliative actions of IL-10 in DSS-induced colitis predominantly results from its macrophage-specific effects. Downregulation of NO and ROS production are central to the protective actions of IL-10.

Show MeSH
Related in: MedlinePlus