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Mincle-mediated translational regulation is required for strong nitric oxide production and inflammation resolution.

Lee WB, Kang JS, Choi WY, Zhang Q, Kim CH, Choi UY, Kim-Ha J, Kim YJ - Nat Commun (2016)

Bottom Line: Here we show that Mincle, the inducible receptor for mycobacterial cord factor, is the key switch for the transition of macrophages from cytokine expression to high nitric oxide production.In addition to its stimulatory role on TLR-mediated transcription, Mincle enhanced the translation of key genes required for nitric oxide synthesis through p38 and eIF5A hypusination, leading to granuloma resolution.Thus, Mincle has dual functions in the promotion and subsequent resolution of inflammation during anti-mycobacterial defence using both transcriptional and translational controls.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Republic of Korea.

ABSTRACT
In response to persistent mycobacteria infection, the host induces a granuloma, which often fails to eradicate bacteria and results in tissue damage. Diverse host receptors are required to control the formation and resolution of granuloma, but little is known concerning their regulatory interactions. Here we show that Mincle, the inducible receptor for mycobacterial cord factor, is the key switch for the transition of macrophages from cytokine expression to high nitric oxide production. In addition to its stimulatory role on TLR-mediated transcription, Mincle enhanced the translation of key genes required for nitric oxide synthesis through p38 and eIF5A hypusination, leading to granuloma resolution. Thus, Mincle has dual functions in the promotion and subsequent resolution of inflammation during anti-mycobacterial defence using both transcriptional and translational controls.

No MeSH data available.


Related in: MedlinePlus

iNOS deficiency and inhibition of eIF5A hypusination aggravate granuloma formation by TDM.(a–e) WT and iNOS−/− mice were injected intravenously with an oil-in-water emulsion of TDM (n>6 mice/group). (a) Histology of lungs at 7 and 14 days after injection (scale bars, 100μm). (b) TDM-induced lung swelling. On days 7 and 14 after injection of TDM, lung swelling was evaluated by LWI. (c) Identification of leucocyte subsets in lung granulomas on day 14 after TDM injection by flow cytometry. The number of neutrophils (PMN, CD11b+ Ly6G+), monocytes (Mono, CD11b+ Ly6G−), T cells (CD3+) and B cells (CD19+) are indicated. (d) ELISA of IL-1β in lung lysates on day 7 or 14 after TDM injection. (e) Immunoblot analysis of active caspase-1 (Casp1 p10) and iNOS in lysates of lungs from WT and iNOS−/− mice injected with TDM; β-actin serves as a loading control (each lane represents an individual mouse). (f–j) Mice were administered with PBS, GC7 or CPX via intraperitoneal injection, and with oil-in-water emulsion of TDM or emulsion alone, via intravenous injection. On day 7 after the indicated injection, lungs were harvested and experiments were performed. (f) Lung histology was examined by H&E staining (scale bars, 100 μm.) (g) TDM-induced lung swelling. At day 7 after the indicated injection, lung swelling was evaluated by LWI. (h) ELISA of IL-1β in lung lysates on day 7 TDM injection. (i) Immunoblot analysis of active caspase-1 (Casp1 p10) and iNOS in lysates of lungs from mice injected with TDM with/without GC7 or CPX, assessed on day 7 after injection; β-actin serves as a loading control (each lane represents an individual mouse). (j) Lethal systemic inflammation by TDM (n=five mice/group, P-value calculated by Mantel–Cox test). *P<0.05, **P<0.01 (two-tailed unpaired Student's t-test). Data are representative of two experiments (b–d,g–i: mean and s.d. of three to five mice per group).
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f7: iNOS deficiency and inhibition of eIF5A hypusination aggravate granuloma formation by TDM.(a–e) WT and iNOS−/− mice were injected intravenously with an oil-in-water emulsion of TDM (n>6 mice/group). (a) Histology of lungs at 7 and 14 days after injection (scale bars, 100μm). (b) TDM-induced lung swelling. On days 7 and 14 after injection of TDM, lung swelling was evaluated by LWI. (c) Identification of leucocyte subsets in lung granulomas on day 14 after TDM injection by flow cytometry. The number of neutrophils (PMN, CD11b+ Ly6G+), monocytes (Mono, CD11b+ Ly6G−), T cells (CD3+) and B cells (CD19+) are indicated. (d) ELISA of IL-1β in lung lysates on day 7 or 14 after TDM injection. (e) Immunoblot analysis of active caspase-1 (Casp1 p10) and iNOS in lysates of lungs from WT and iNOS−/− mice injected with TDM; β-actin serves as a loading control (each lane represents an individual mouse). (f–j) Mice were administered with PBS, GC7 or CPX via intraperitoneal injection, and with oil-in-water emulsion of TDM or emulsion alone, via intravenous injection. On day 7 after the indicated injection, lungs were harvested and experiments were performed. (f) Lung histology was examined by H&E staining (scale bars, 100 μm.) (g) TDM-induced lung swelling. At day 7 after the indicated injection, lung swelling was evaluated by LWI. (h) ELISA of IL-1β in lung lysates on day 7 TDM injection. (i) Immunoblot analysis of active caspase-1 (Casp1 p10) and iNOS in lysates of lungs from mice injected with TDM with/without GC7 or CPX, assessed on day 7 after injection; β-actin serves as a loading control (each lane represents an individual mouse). (j) Lethal systemic inflammation by TDM (n=five mice/group, P-value calculated by Mantel–Cox test). *P<0.05, **P<0.01 (two-tailed unpaired Student's t-test). Data are representative of two experiments (b–d,g–i: mean and s.d. of three to five mice per group).

Mentions: A granuloma is an organized collection of immune cells, mostly macrophages, induced by sustained presence of mycobacteria before killing them35. Excessive granuloma formation by high IL-1β would result in severe tissue damage due to uncontrolled necrotic cell death363738. Thus, delayed NO production following IL-1β activation may contribute not only to bacterial killing, but also to anti-inflammation by downregulating IL-1β. To confirm the negative regulatory function of NO in the inflammatory response, we injected TDM intravenously with oil-in-water emulsion, and compared the extent of pulmonary granuloma formation in WT and iNOS−/− mice. Both WT and iNOS−/− mice showed an increase in lung weight index (LWI) and granuloma formation at day 7 after TDM injection (Fig. 7a,b). Similar to previous reports39, TDM-induced granuloma was resolved and partially disappeared 14 days post administration in the WT lung. However, the granuloma area and LWI were increased in iNOS−/− mice, rather than being resolved. Consistent with the severe histopathology, iNOS−/− mouse lungs at day 14 showed significantly increased infiltration of neutrophil (CD11b+Ly6G+) and monocyte (CD11b+Ly6G−), but not lymphocyte (Fig. 7c). Although we cannot rule out an indirect effect caused by NO deficiency, this pathological damage appeared to be caused by increased inflammasome activation: increased IL-1β secretion and cleavage of caspase-1 was observed in iNOS mutant mouse lungs (Fig. 7d,e). Therefore, iNOS is required for IL-1β downregulation after the confinement of mycobacterial substances within the granuloma to prevent the excessive spread of inflammatory response.


Mincle-mediated translational regulation is required for strong nitric oxide production and inflammation resolution.

Lee WB, Kang JS, Choi WY, Zhang Q, Kim CH, Choi UY, Kim-Ha J, Kim YJ - Nat Commun (2016)

iNOS deficiency and inhibition of eIF5A hypusination aggravate granuloma formation by TDM.(a–e) WT and iNOS−/− mice were injected intravenously with an oil-in-water emulsion of TDM (n>6 mice/group). (a) Histology of lungs at 7 and 14 days after injection (scale bars, 100μm). (b) TDM-induced lung swelling. On days 7 and 14 after injection of TDM, lung swelling was evaluated by LWI. (c) Identification of leucocyte subsets in lung granulomas on day 14 after TDM injection by flow cytometry. The number of neutrophils (PMN, CD11b+ Ly6G+), monocytes (Mono, CD11b+ Ly6G−), T cells (CD3+) and B cells (CD19+) are indicated. (d) ELISA of IL-1β in lung lysates on day 7 or 14 after TDM injection. (e) Immunoblot analysis of active caspase-1 (Casp1 p10) and iNOS in lysates of lungs from WT and iNOS−/− mice injected with TDM; β-actin serves as a loading control (each lane represents an individual mouse). (f–j) Mice were administered with PBS, GC7 or CPX via intraperitoneal injection, and with oil-in-water emulsion of TDM or emulsion alone, via intravenous injection. On day 7 after the indicated injection, lungs were harvested and experiments were performed. (f) Lung histology was examined by H&E staining (scale bars, 100 μm.) (g) TDM-induced lung swelling. At day 7 after the indicated injection, lung swelling was evaluated by LWI. (h) ELISA of IL-1β in lung lysates on day 7 TDM injection. (i) Immunoblot analysis of active caspase-1 (Casp1 p10) and iNOS in lysates of lungs from mice injected with TDM with/without GC7 or CPX, assessed on day 7 after injection; β-actin serves as a loading control (each lane represents an individual mouse). (j) Lethal systemic inflammation by TDM (n=five mice/group, P-value calculated by Mantel–Cox test). *P<0.05, **P<0.01 (two-tailed unpaired Student's t-test). Data are representative of two experiments (b–d,g–i: mean and s.d. of three to five mice per group).
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f7: iNOS deficiency and inhibition of eIF5A hypusination aggravate granuloma formation by TDM.(a–e) WT and iNOS−/− mice were injected intravenously with an oil-in-water emulsion of TDM (n>6 mice/group). (a) Histology of lungs at 7 and 14 days after injection (scale bars, 100μm). (b) TDM-induced lung swelling. On days 7 and 14 after injection of TDM, lung swelling was evaluated by LWI. (c) Identification of leucocyte subsets in lung granulomas on day 14 after TDM injection by flow cytometry. The number of neutrophils (PMN, CD11b+ Ly6G+), monocytes (Mono, CD11b+ Ly6G−), T cells (CD3+) and B cells (CD19+) are indicated. (d) ELISA of IL-1β in lung lysates on day 7 or 14 after TDM injection. (e) Immunoblot analysis of active caspase-1 (Casp1 p10) and iNOS in lysates of lungs from WT and iNOS−/− mice injected with TDM; β-actin serves as a loading control (each lane represents an individual mouse). (f–j) Mice were administered with PBS, GC7 or CPX via intraperitoneal injection, and with oil-in-water emulsion of TDM or emulsion alone, via intravenous injection. On day 7 after the indicated injection, lungs were harvested and experiments were performed. (f) Lung histology was examined by H&E staining (scale bars, 100 μm.) (g) TDM-induced lung swelling. At day 7 after the indicated injection, lung swelling was evaluated by LWI. (h) ELISA of IL-1β in lung lysates on day 7 TDM injection. (i) Immunoblot analysis of active caspase-1 (Casp1 p10) and iNOS in lysates of lungs from mice injected with TDM with/without GC7 or CPX, assessed on day 7 after injection; β-actin serves as a loading control (each lane represents an individual mouse). (j) Lethal systemic inflammation by TDM (n=five mice/group, P-value calculated by Mantel–Cox test). *P<0.05, **P<0.01 (two-tailed unpaired Student's t-test). Data are representative of two experiments (b–d,g–i: mean and s.d. of three to five mice per group).
Mentions: A granuloma is an organized collection of immune cells, mostly macrophages, induced by sustained presence of mycobacteria before killing them35. Excessive granuloma formation by high IL-1β would result in severe tissue damage due to uncontrolled necrotic cell death363738. Thus, delayed NO production following IL-1β activation may contribute not only to bacterial killing, but also to anti-inflammation by downregulating IL-1β. To confirm the negative regulatory function of NO in the inflammatory response, we injected TDM intravenously with oil-in-water emulsion, and compared the extent of pulmonary granuloma formation in WT and iNOS−/− mice. Both WT and iNOS−/− mice showed an increase in lung weight index (LWI) and granuloma formation at day 7 after TDM injection (Fig. 7a,b). Similar to previous reports39, TDM-induced granuloma was resolved and partially disappeared 14 days post administration in the WT lung. However, the granuloma area and LWI were increased in iNOS−/− mice, rather than being resolved. Consistent with the severe histopathology, iNOS−/− mouse lungs at day 14 showed significantly increased infiltration of neutrophil (CD11b+Ly6G+) and monocyte (CD11b+Ly6G−), but not lymphocyte (Fig. 7c). Although we cannot rule out an indirect effect caused by NO deficiency, this pathological damage appeared to be caused by increased inflammasome activation: increased IL-1β secretion and cleavage of caspase-1 was observed in iNOS mutant mouse lungs (Fig. 7d,e). Therefore, iNOS is required for IL-1β downregulation after the confinement of mycobacterial substances within the granuloma to prevent the excessive spread of inflammatory response.

Bottom Line: Here we show that Mincle, the inducible receptor for mycobacterial cord factor, is the key switch for the transition of macrophages from cytokine expression to high nitric oxide production.In addition to its stimulatory role on TLR-mediated transcription, Mincle enhanced the translation of key genes required for nitric oxide synthesis through p38 and eIF5A hypusination, leading to granuloma resolution.Thus, Mincle has dual functions in the promotion and subsequent resolution of inflammation during anti-mycobacterial defence using both transcriptional and translational controls.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Republic of Korea.

ABSTRACT
In response to persistent mycobacteria infection, the host induces a granuloma, which often fails to eradicate bacteria and results in tissue damage. Diverse host receptors are required to control the formation and resolution of granuloma, but little is known concerning their regulatory interactions. Here we show that Mincle, the inducible receptor for mycobacterial cord factor, is the key switch for the transition of macrophages from cytokine expression to high nitric oxide production. In addition to its stimulatory role on TLR-mediated transcription, Mincle enhanced the translation of key genes required for nitric oxide synthesis through p38 and eIF5A hypusination, leading to granuloma resolution. Thus, Mincle has dual functions in the promotion and subsequent resolution of inflammation during anti-mycobacterial defence using both transcriptional and translational controls.

No MeSH data available.


Related in: MedlinePlus