Hemozoin or malaria pigment is the detoxification product of heme, released into the circulation during malaria infection. Once phegocytized by host cells, it induces the production of cytokines, such as IL-1β, whose proform is cleaved by caspase-1, a protease involved in a multiprotein complex called the inflammasome. lt has been recently reported that synthetic malaria pigment activates the inflammasome and that membrane lipid rafts are potentially involved, but the mechanisms are not yet known. Ln the present study we provide first evidence of the activation of the inflammasome and production of IL-1β by native hemozoin (nHZ) extracted from parasite cultures and not only by synthetic malaria pigment. We observed that the production of IL-1β by nHZ-treated mouse bone marrow macrophages was impaired in the presence of zYVAD-fmk, a caspase-1 inhibitor and in caspase-1-/- cells. Phagocytosis of nHZ was crucial for IL-1β production, since in the presence of the phagocytosis inhibitor, cytochalasin D, the cells did not produced IL-1β. Moreover; when we examined the involvement of cathepsins, proteases released upon lysosomal or phagosomal destabilization, we found that in the presence of inhibitors for cathepsins the production of IL-1β was decreased. lnflammasome activation by nHZ was also associated with generation of oxidative stress measured with the fluorescent indicator 5-(and•6ychloromethyl•2',7'-dlchlomdihydrottuoresoein diacelate acetyl ester (DCF-DA). In fact, antioxidants decreased both intracellular reactive oxygen species and IL-1β production. Furthermore, membrane lipid peroxidation in nHZ-treated macrophages was demonstrated by detemining the levels of thiobarbituric acid reactive substances (TBARS). Additionally some of the effects of nHZ were reproduced by using 4-hydroxynonenal (HNE), a major aldehydic end-product of membrane peroxidation. HNE induced IL-1β secretion in macrophages, which was decreased by zYVAD-fmk and in caspase-1-/- cells. ln the presence of inhibitors for cathepsins, the production of IL-1β was also decreased. Taken together these findings suggest an indirect mechanism of activation of the inflammasome by nHZ exists through the peroxidation of lipids present in the cell membranes upon oxidative burst. Research funded by the EU-AntiMal-lP•018834 and PUR 2008, italy.

Malarial hemozoin activates inflammasome through membrane lipid peroxidation / Y. Corbett, S. D’Alessandro, N. Basilico, S. Parapini, P. Crauwels, M.F. Omodeo-Salè, K. Fitzgerald, D.T. Golenbock, D. Taramelli. ((Intervento presentato al convegno 2010 Keystone Symposia. Malaria: new approaches to understanding host-parasite interactions tenutosi a Copper Mountain nel 2010.

Malarial hemozoin activates inflammasome through membrane lipid peroxidation

Y. Corbett
Primo
;
S. D’Alessandro
Secondo
;
N. Basilico;S. Parapini;M.F. Omodeo-Salè;D. Taramelli
Ultimo
2010

Abstract

Hemozoin or malaria pigment is the detoxification product of heme, released into the circulation during malaria infection. Once phegocytized by host cells, it induces the production of cytokines, such as IL-1β, whose proform is cleaved by caspase-1, a protease involved in a multiprotein complex called the inflammasome. lt has been recently reported that synthetic malaria pigment activates the inflammasome and that membrane lipid rafts are potentially involved, but the mechanisms are not yet known. Ln the present study we provide first evidence of the activation of the inflammasome and production of IL-1β by native hemozoin (nHZ) extracted from parasite cultures and not only by synthetic malaria pigment. We observed that the production of IL-1β by nHZ-treated mouse bone marrow macrophages was impaired in the presence of zYVAD-fmk, a caspase-1 inhibitor and in caspase-1-/- cells. Phagocytosis of nHZ was crucial for IL-1β production, since in the presence of the phagocytosis inhibitor, cytochalasin D, the cells did not produced IL-1β. Moreover; when we examined the involvement of cathepsins, proteases released upon lysosomal or phagosomal destabilization, we found that in the presence of inhibitors for cathepsins the production of IL-1β was decreased. lnflammasome activation by nHZ was also associated with generation of oxidative stress measured with the fluorescent indicator 5-(and•6ychloromethyl•2',7'-dlchlomdihydrottuoresoein diacelate acetyl ester (DCF-DA). In fact, antioxidants decreased both intracellular reactive oxygen species and IL-1β production. Furthermore, membrane lipid peroxidation in nHZ-treated macrophages was demonstrated by detemining the levels of thiobarbituric acid reactive substances (TBARS). Additionally some of the effects of nHZ were reproduced by using 4-hydroxynonenal (HNE), a major aldehydic end-product of membrane peroxidation. HNE induced IL-1β secretion in macrophages, which was decreased by zYVAD-fmk and in caspase-1-/- cells. ln the presence of inhibitors for cathepsins, the production of IL-1β was also decreased. Taken together these findings suggest an indirect mechanism of activation of the inflammasome by nHZ exists through the peroxidation of lipids present in the cell membranes upon oxidative burst. Research funded by the EU-AntiMal-lP•018834 and PUR 2008, italy.
apr-2010
Settore MED/04 - Patologia Generale
Settore BIO/10 - Biochimica
Malarial hemozoin activates inflammasome through membrane lipid peroxidation / Y. Corbett, S. D’Alessandro, N. Basilico, S. Parapini, P. Crauwels, M.F. Omodeo-Salè, K. Fitzgerald, D.T. Golenbock, D. Taramelli. ((Intervento presentato al convegno 2010 Keystone Symposia. Malaria: new approaches to understanding host-parasite interactions tenutosi a Copper Mountain nel 2010.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/166690
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