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Netrin-1 regulates the inflammatory response of neutrophils and macrophages, and suppresses ischemic acute kidney injury by inhibiting COX-2-mediated PGE2 production.

Ranganathan PV, Jayakumar C, Mohamed R, Dong Z, Ramesh G - Kidney Int. (2013)

Bottom Line: This was associated with reduced apoptosis, inflammatory cytokine and chemokine expression, and improved kidney function.Moreover, netrin-1 regulates COX-2 expression at the transcriptional level through the regulation of NFκB activation.This could be a potential drug for treating many inflammatory immune disorders.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine and Vascular Biology Center, Georgia Health Sciences University, Augusta, Georgia 30912, USA.

ABSTRACT
Netrin-1 regulates inflammation but the mechanism by which this occurs is unknown. Here we explore the role of netrin-1 in regulating the production of the prostanoid metabolite PGE2 from neutrophils in in vitro and in vivo disease models. Ischemia reperfusion in wild-type and RAG-1 knockout mice induced severe kidney injury that was associated with a large increase in neutrophil infiltration and COX-2 expression in the infiltrating leukocytes. Administration of netrin-1 suppressed COX-2 expression, PGE2 and thromboxane production, and neutrophil infiltration into the kidney. This was associated with reduced apoptosis, inflammatory cytokine and chemokine expression, and improved kidney function. Treatment with the PGE2 receptor EP4 agonist enhanced neutrophil infiltration and renal injury, which was not inhibited by netrin-1. Consistent with in vivo data, both LPS- and IFNγ-induced inflammatory cytokine production in macrophages and IL-17-induced IFNγ production in neutrophils were suppressed by netrin-1 in vitro by suppression of COX-2 expression. Moreover, netrin-1 regulates COX-2 expression at the transcriptional level through the regulation of NFκB activation. Thus, netrin-1 regulates the inflammatory response of neutrophils and macrophages through suppression of COX-2-mediated PGE2 production. This could be a potential drug for treating many inflammatory immune disorders.

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Regulation of COX-2 expression and PGE2 production by netrin-1 in macrophages, neutrophils and T cells. A. IFNγ-induced COX-2 expression was suppressed by addition of netrin-1 in macrophages. Netrin-1-mediated suppression of COX-2 expression was abolished by addition of PGE2. #, p<0.001 vs. all other groups. *p<0.001 vs. IFNγ-treated. B. IFNγ and LPS-induced increase in PGE2 production in macrophages was suppressed with netrin-1 treatment. *, p<0.005 vs. control. +, p<0.001 vs. IFNγ and LPS-treated groups. C and D. IFNγ-induced production of chemokines MCP-1 and IP-10 was inhibited in netrin-1 treated macrophages, which was abolished with PGE2 addition. #, p<0.001 vs. all other groups. *, p<0.001 vs. IFNγ-treated. E and F. IL-17-induced COX-2 expression and inflammatory cytokine production is suppressed by netrin-1 in neutrophils in vitro. E. IL-17 induced the expression of TNFα, COX-2, and prostaglandin E synthase 2 (ptges2) in neutrophils, which was suppressed by addition of netrin-1. Addition of PGE2 along with netrin-1 abolished the suppressive effect of netrin-1. *, p<0.001 vs. all other groups. F. IL-17-induced IFNγ production in neutrophils is suppressed by netrin-1, which was abolished by addition of PGE2. *, p<0.001 vs. all other groups. Values are mean ± SEM. n=4-6.
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Figure 6: Regulation of COX-2 expression and PGE2 production by netrin-1 in macrophages, neutrophils and T cells. A. IFNγ-induced COX-2 expression was suppressed by addition of netrin-1 in macrophages. Netrin-1-mediated suppression of COX-2 expression was abolished by addition of PGE2. #, p<0.001 vs. all other groups. *p<0.001 vs. IFNγ-treated. B. IFNγ and LPS-induced increase in PGE2 production in macrophages was suppressed with netrin-1 treatment. *, p<0.005 vs. control. +, p<0.001 vs. IFNγ and LPS-treated groups. C and D. IFNγ-induced production of chemokines MCP-1 and IP-10 was inhibited in netrin-1 treated macrophages, which was abolished with PGE2 addition. #, p<0.001 vs. all other groups. *, p<0.001 vs. IFNγ-treated. E and F. IL-17-induced COX-2 expression and inflammatory cytokine production is suppressed by netrin-1 in neutrophils in vitro. E. IL-17 induced the expression of TNFα, COX-2, and prostaglandin E synthase 2 (ptges2) in neutrophils, which was suppressed by addition of netrin-1. Addition of PGE2 along with netrin-1 abolished the suppressive effect of netrin-1. *, p<0.001 vs. all other groups. F. IL-17-induced IFNγ production in neutrophils is suppressed by netrin-1, which was abolished by addition of PGE2. *, p<0.001 vs. all other groups. Values are mean ± SEM. n=4-6.

Mentions: Since both monocytes and neutrophils are present in RAG-1 knockout animals and these two cell types are regulated by netrin-1 during ischemia reperfusion injury [9], we determined whether COX-2-mediated inflammation is regulated by netrin-1 in both macrophages and neutrophils. We hypothesized that netrin-1 regulates inflammatory responses of macrophages and neutrophils by suppressing COX-2-mediated PGE2 production, thereby suppressing inflammatory cytokine and chemokine production. To determine this possibility, we characterized the mechanism of netrin-1-mediated suppression of COX-2 and PGE2 production in a macrophage cell line. As shown in Figure 6, addition of either IFNγ or LPS treatment induced a large increase in COX-2 expression and PGE2 production, but not COX-1 expression (Figure 6A and C). Both IFNγ and LPS-induced COX-2 and PGE2 production were suppressed in netrin-1 treated macrophages. IFNγ also induced a large increase in MCP-1 and IP-10 production, which was inhibited by netrin-1 (Figure 6B and D). The netrin-1 mediated suppressive effect on chemokine production was abolished when PGE2 is added to the culture, suggesting that the netrin-1 effect is at the level of COX-2 expression.


Netrin-1 regulates the inflammatory response of neutrophils and macrophages, and suppresses ischemic acute kidney injury by inhibiting COX-2-mediated PGE2 production.

Ranganathan PV, Jayakumar C, Mohamed R, Dong Z, Ramesh G - Kidney Int. (2013)

Regulation of COX-2 expression and PGE2 production by netrin-1 in macrophages, neutrophils and T cells. A. IFNγ-induced COX-2 expression was suppressed by addition of netrin-1 in macrophages. Netrin-1-mediated suppression of COX-2 expression was abolished by addition of PGE2. #, p<0.001 vs. all other groups. *p<0.001 vs. IFNγ-treated. B. IFNγ and LPS-induced increase in PGE2 production in macrophages was suppressed with netrin-1 treatment. *, p<0.005 vs. control. +, p<0.001 vs. IFNγ and LPS-treated groups. C and D. IFNγ-induced production of chemokines MCP-1 and IP-10 was inhibited in netrin-1 treated macrophages, which was abolished with PGE2 addition. #, p<0.001 vs. all other groups. *, p<0.001 vs. IFNγ-treated. E and F. IL-17-induced COX-2 expression and inflammatory cytokine production is suppressed by netrin-1 in neutrophils in vitro. E. IL-17 induced the expression of TNFα, COX-2, and prostaglandin E synthase 2 (ptges2) in neutrophils, which was suppressed by addition of netrin-1. Addition of PGE2 along with netrin-1 abolished the suppressive effect of netrin-1. *, p<0.001 vs. all other groups. F. IL-17-induced IFNγ production in neutrophils is suppressed by netrin-1, which was abolished by addition of PGE2. *, p<0.001 vs. all other groups. Values are mean ± SEM. n=4-6.
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Figure 6: Regulation of COX-2 expression and PGE2 production by netrin-1 in macrophages, neutrophils and T cells. A. IFNγ-induced COX-2 expression was suppressed by addition of netrin-1 in macrophages. Netrin-1-mediated suppression of COX-2 expression was abolished by addition of PGE2. #, p<0.001 vs. all other groups. *p<0.001 vs. IFNγ-treated. B. IFNγ and LPS-induced increase in PGE2 production in macrophages was suppressed with netrin-1 treatment. *, p<0.005 vs. control. +, p<0.001 vs. IFNγ and LPS-treated groups. C and D. IFNγ-induced production of chemokines MCP-1 and IP-10 was inhibited in netrin-1 treated macrophages, which was abolished with PGE2 addition. #, p<0.001 vs. all other groups. *, p<0.001 vs. IFNγ-treated. E and F. IL-17-induced COX-2 expression and inflammatory cytokine production is suppressed by netrin-1 in neutrophils in vitro. E. IL-17 induced the expression of TNFα, COX-2, and prostaglandin E synthase 2 (ptges2) in neutrophils, which was suppressed by addition of netrin-1. Addition of PGE2 along with netrin-1 abolished the suppressive effect of netrin-1. *, p<0.001 vs. all other groups. F. IL-17-induced IFNγ production in neutrophils is suppressed by netrin-1, which was abolished by addition of PGE2. *, p<0.001 vs. all other groups. Values are mean ± SEM. n=4-6.
Mentions: Since both monocytes and neutrophils are present in RAG-1 knockout animals and these two cell types are regulated by netrin-1 during ischemia reperfusion injury [9], we determined whether COX-2-mediated inflammation is regulated by netrin-1 in both macrophages and neutrophils. We hypothesized that netrin-1 regulates inflammatory responses of macrophages and neutrophils by suppressing COX-2-mediated PGE2 production, thereby suppressing inflammatory cytokine and chemokine production. To determine this possibility, we characterized the mechanism of netrin-1-mediated suppression of COX-2 and PGE2 production in a macrophage cell line. As shown in Figure 6, addition of either IFNγ or LPS treatment induced a large increase in COX-2 expression and PGE2 production, but not COX-1 expression (Figure 6A and C). Both IFNγ and LPS-induced COX-2 and PGE2 production were suppressed in netrin-1 treated macrophages. IFNγ also induced a large increase in MCP-1 and IP-10 production, which was inhibited by netrin-1 (Figure 6B and D). The netrin-1 mediated suppressive effect on chemokine production was abolished when PGE2 is added to the culture, suggesting that the netrin-1 effect is at the level of COX-2 expression.

Bottom Line: This was associated with reduced apoptosis, inflammatory cytokine and chemokine expression, and improved kidney function.Moreover, netrin-1 regulates COX-2 expression at the transcriptional level through the regulation of NFκB activation.This could be a potential drug for treating many inflammatory immune disorders.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine and Vascular Biology Center, Georgia Health Sciences University, Augusta, Georgia 30912, USA.

ABSTRACT
Netrin-1 regulates inflammation but the mechanism by which this occurs is unknown. Here we explore the role of netrin-1 in regulating the production of the prostanoid metabolite PGE2 from neutrophils in in vitro and in vivo disease models. Ischemia reperfusion in wild-type and RAG-1 knockout mice induced severe kidney injury that was associated with a large increase in neutrophil infiltration and COX-2 expression in the infiltrating leukocytes. Administration of netrin-1 suppressed COX-2 expression, PGE2 and thromboxane production, and neutrophil infiltration into the kidney. This was associated with reduced apoptosis, inflammatory cytokine and chemokine expression, and improved kidney function. Treatment with the PGE2 receptor EP4 agonist enhanced neutrophil infiltration and renal injury, which was not inhibited by netrin-1. Consistent with in vivo data, both LPS- and IFNγ-induced inflammatory cytokine production in macrophages and IL-17-induced IFNγ production in neutrophils were suppressed by netrin-1 in vitro by suppression of COX-2 expression. Moreover, netrin-1 regulates COX-2 expression at the transcriptional level through the regulation of NFκB activation. Thus, netrin-1 regulates the inflammatory response of neutrophils and macrophages through suppression of COX-2-mediated PGE2 production. This could be a potential drug for treating many inflammatory immune disorders.

Show MeSH
Related in: MedlinePlus