Hemozoin-fed (HZ-fed) monocytes are strongly exposed to oxidative stress, shed large amounts of peroxidation derivatives with subsequent impairment of numerous functions and overproduce proinflammatory cytokines. Nevertheless histopathologic features of autoptic tissues from patients with severe malaria show abundant presence of HZ in Kupffer cells and other tissue macrophages, suggesting that function impairment and cytokines production are not accompanied by cells death. The aim of present study is to clarify the role of hemozoin on cell survival focusing on the involvement and temporal setting of proinflammatory and anti-apoptotic molecules. Analysis through immunocytochemistry and flow cytometry showed that long term cell viability was unaffected by hemozoin in human monocytes. Short term analysis through macro-array of a complete panel of cytokines and real-time RT-PCR experiments showed that HZ induced immediately IL-1beta gene expression, further followed by additional transcription of eight chemokines (IL-8, ENA-78, GROalpha, GRObeta, GROgamma,MIP-1alpha, MIP-1beta and MCP-1), two cytokines (TNFalpha and IL-1RA), and cytokine/chemokine-related proteolytic enzyme MMP-9. Furthermore, real-time RT-PCR analysis showed that 15-HETE, a potent lipoperoxidation derivative generated by HZ through heme-catalysis, recapitulated HZ effects on five chemokines expression. Intermediate term investigation by western blotting showed that HZ increased protein expression of HSP27, a chemokine-related molecule with anti-apoptotic properties. Collectively, present data suggest that apoptosis of hemozoin-fed monocytes is prevented through a cascade involving 15-HETE-mediated higher transcription of IL-1beta, rapidly endorsed by chemokines, TNFalpha, MMP-9 and IL-1RA transcription and up-regulation of anti-apoptotic HSP27 protein expression, favouring persistence of impaired monocytes in the bloodstream and clinical progress towards fatal complicated malaria.
Enhanced Proinflammatory Response and Missing Apoptosis in Hemozoin-Fed Human Monocytes: a HSP-27-Mediated Anomaly in Falciparum Malaria
PRATO, Mauro;ULLIERS, Daniela;GALLO, Valentina;KEILING, BRIGITTE EVELIN;AKIDE-NDUNGE, OSCAR BATE;MANDILI, GIORGIA;SAVIOZZI, Silvia;CALOGERO, Raffaele Adolfo;ARESE, Paolo;GIRIBALDI, Giuliana
2010-01-01
Abstract
Hemozoin-fed (HZ-fed) monocytes are strongly exposed to oxidative stress, shed large amounts of peroxidation derivatives with subsequent impairment of numerous functions and overproduce proinflammatory cytokines. Nevertheless histopathologic features of autoptic tissues from patients with severe malaria show abundant presence of HZ in Kupffer cells and other tissue macrophages, suggesting that function impairment and cytokines production are not accompanied by cells death. The aim of present study is to clarify the role of hemozoin on cell survival focusing on the involvement and temporal setting of proinflammatory and anti-apoptotic molecules. Analysis through immunocytochemistry and flow cytometry showed that long term cell viability was unaffected by hemozoin in human monocytes. Short term analysis through macro-array of a complete panel of cytokines and real-time RT-PCR experiments showed that HZ induced immediately IL-1beta gene expression, further followed by additional transcription of eight chemokines (IL-8, ENA-78, GROalpha, GRObeta, GROgamma,MIP-1alpha, MIP-1beta and MCP-1), two cytokines (TNFalpha and IL-1RA), and cytokine/chemokine-related proteolytic enzyme MMP-9. Furthermore, real-time RT-PCR analysis showed that 15-HETE, a potent lipoperoxidation derivative generated by HZ through heme-catalysis, recapitulated HZ effects on five chemokines expression. Intermediate term investigation by western blotting showed that HZ increased protein expression of HSP27, a chemokine-related molecule with anti-apoptotic properties. Collectively, present data suggest that apoptosis of hemozoin-fed monocytes is prevented through a cascade involving 15-HETE-mediated higher transcription of IL-1beta, rapidly endorsed by chemokines, TNFalpha, MMP-9 and IL-1RA transcription and up-regulation of anti-apoptotic HSP27 protein expression, favouring persistence of impaired monocytes in the bloodstream and clinical progress towards fatal complicated malaria.
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