Objective:Avidly phagocytosed hemozoin(malarial pigment) alters several functions of human monocytes and stimulates generation of several cytokines.Recently,we showed that phagocytosis of hemozoin by human monocytes i...Objective:Avidly phagocytosed hemozoin(malarial pigment) alters several functions of human monocytes and stimulates generation of several cytokines.Recently,we showed that phagocytosis of hemozoin by human monocytes increases expression and activity of matrix metalloproteinase-9,a proteolytic enzyme available in specific gelatinase granules,which contain several enzymes including lysozyme.Present work investigated active lysozyme release after phagocytosis of hemozoin and its dependence on production of tumor necrosis factor alpha. Methods:After phagocytosis of hemozoin,hemozoin-containing trophozoites or control meals(opsonized nonparasitized red blood cells and latex particles),monocyte supematants were monitored for 2 hours,in presence of blocking anti-human tumor necrosis factor alpha antibodies or recombinant human tumor necrosis factor alpha cytokine in selected experiments.Lysozyme release was evaluated by a specific spectrometric assay measuring lysozyme activity after coincubation of cell supematants with suspensions of Mycrococcus Lysodeikticus,while levels of soluble tumor necrosis factor alpha were analyzed by specific enzyme-linked immunodsorbent assay. Results:Levels of lysozyme activity and soluble tumor necrosis factor alpha protein were increased in hemozoin in-or trophozoites-laden monocytes supematants.Phagocytosis per se(control meals) also increased lysozyme release,but levels were significantly lower than those obtained after phagocytosis of hemozoin or trophozoites. Interestingly,all effects on lysozyme release observed after phagocytosis were abrogated by blocking anti-human tumor necrosis factor alpha antibodies,while they were mimicked by recombinant human tumor necrosis factor alpha cytokine.Conclusions:Present work shows that phagocytosis of hemozoin promotes monocyte degranulation and enhances active lysozyme release.The effect requires tumor necrosis factor alpha mediation.展开更多
Objective:To investigate whether the increase of tumor necrosis factor alpha is dependent on lipidic component of malarial pigment.Methods:Adherent human monocytes were fed for 3 hours with different meals(native hemo...Objective:To investigate whether the increase of tumor necrosis factor alpha is dependent on lipidic component of malarial pigment.Methods:Adherent human monocytes were fed for 3 hours with different meals(native hemozoin;lipid free hemozoin;and control latex particles),then tumor necrosis factor alpha was monitored in cell supernatants up to 48 hours through western blotting or specific enzyme-linked immunoadsorbent assay.In selected experiments,unfed monocytes were treated with different doses of 15(S,R)-hydroxy-6,8,11,13-eicosatetraenoic acid or 4-hydroxynonenal instead of phagocytosis.Results:Hemozoin-fed monocytes produced higher levels of tumor necrosis factor alpha than unstimulated and latex-fed cells, while lipid-free hemozoin did not reproduce these results.Additionally,hemozoin effects were mimicked dose-dependently by 15(S,R)-hydroxy-6,8,11,13-eicosatetraenoic acid,but not by 4-hydroxynonenal.Conclusions:Present data suggest an essential role for lipids in hemozoindependent enhanced release of tumor necrosis factor alpha from monocytes,and 15(S,R)hydroxy -6,8,11,13-eicosatetraenoic acid could be one possible specific mediator.展开更多
More than 2 billion people are at risk of malaria,which primarily affects poor populations in tropical and subtropical areas,including Southern Asia.As malaria incidence has been reduced strongly in some parts of ende...More than 2 billion people are at risk of malaria,which primarily affects poor populations in tropical and subtropical areas,including Southern Asia.As malaria incidence has been reduced strongly in some parts of endemic regions by combinations of interventions,including artemisinin-based therapies and insecticide-treated bed nets,a new goal has been established recently by charity foundations which support research on malaria:the worldwide eradication of the pathology.Doing away with control approaches which have been applied for the last 50 years and more focus on elimination objectives will deeply change priorities in the area of malaria treatment,chemoprevention,vector control,vaccine research and health system assessment.In this review,actual knowledge on pathogenesis and pharmacology is discussed,and new drugs, vaccines and insecticides are described.展开更多
During malaria infection,elevated levels of pro-inflammatory mediators and nitric;oxide production have been associated with pathogenesis and disease severity.Previous in vitro and in vivo studies have proposed that b...During malaria infection,elevated levels of pro-inflammatory mediators and nitric;oxide production have been associated with pathogenesis and disease severity.Previous in vitro and in vivo studies have proposed that both Plasmodium falciparum hemozoin and glycosylphosphatidylinositols are able to modulate blood mononuclear cells,contributing to stimulation of signal transduction and downstream regulation of the NF-KB signaling pathway,and subsequently leading to the production of pro-inflammatory cytokines,chemokines,and nitric oxide.The present review summarizes the published in vitro and in vivo studies that have investigated the mechanism of intracellular signal transduction and activation of the NF-KB signaling pathway in blood mononuclear cells after being inducted by Plasmodium falciparum malaria components.Particular attention is paid to hemozoin and glycosylphosphatidylinositols which reflect the important mechanism of signaling pathways involved in immune response.展开更多
Objective:To investigate the effect of malarial pigment(hemozoin,HZ) on expression of heat shock proteins(HSPs) and cell viability in human monocytes by using a stable cell line(THP-1 cells).Methods:THP-1 cells were f...Objective:To investigate the effect of malarial pigment(hemozoin,HZ) on expression of heat shock proteins(HSPs) and cell viability in human monocytes by using a stable cell line(THP-1 cells).Methods:THP-1 cells were fed with native HZ or treated with pro-apoptotic molecule gliotoxin for 9 h.Thereafter,the protein expression of HSP-27 and HSP-70 was evaluated by western blotting.Alternatively,HZ-fed cells were cultured up to 72 h and cell viability parameters(survival,apoptosis and necrosis rates) were measured by flow cytometric analysis. Results:HZ increased basal protein levels of HSP-27 without altering those of HSP-70 in THP-1 cells,and promoted long-term cell survival without inducing apoptosis.As expected,gliotoxin inhibited HSP-27 protein expression and promoted long-term cell apoptosis.Conclusions: Present data show that HZ prevents cell apoptosis and enhances the expression of anli-apoptotic HSP-27 in THP-1 cells,confirming the previous evidences obtained from HZ-fed immunopurified monocytes.Since the use of a stable cell line is pivotal to perform HSP-27 silencing experiments, monocytic THP-1 cells could be a good candidate line for such an approach,which is heavily required to clarify the role of HSP-27 in survival of impaired HZ-fed monocytes during falciparum malaria.展开更多
Malaria is one of the leading causes of mortality and morbidity in developing countries. Accurate and complete diagnosis is key for effective treatment of the disease. However, mainstream malaria diagnostic techniques...Malaria is one of the leading causes of mortality and morbidity in developing countries. Accurate and complete diagnosis is key for effective treatment of the disease. However, mainstream malaria diagnostic techniques suffer from a number of shortcomings. There is therefore an urgent need for development of new and more efficient techniques for malaria diagnosis. In vivo Photoacoustic spectroscopy is an emerging technique, which has great potential of delivering a nearly ideal method for early diagnosis of the disease. The technique promises to be highly sensitive and specific. In this paper, a description of photoacoustic malaria sensing is given. This is followed by a review of photoacoustic-based malaria diagnostic techniques and suggestions for future improvements.展开更多
Malaria is one of the leading killer diseases in sub-Saharan Africa. Although the disease is curable, early and accurate diagnosis is key to effective therapy. Existing malaria diagnostic techniques have low detection...Malaria is one of the leading killer diseases in sub-Saharan Africa. Although the disease is curable, early and accurate diagnosis is key to effective therapy. Existing malaria diagnostic techniques have low detection accuracy especially when the parasite load in the blood is low. In this paper, we report on a simple photo-thermal based technique for detection of the Plasmodium parasites’ biomarker (hemozoin) in blood smear samples. The technique has demonstrated 100% Plasmodium detection sensitivity and specificity from the ten blood smear test samples used.展开更多
Malaria is a disease that has drawn worldwide attention due to the alarming rise of mortality rates particularly in third world countries. During the Plasmodium parasite intraerythrocytic life cycle, metabolic process...Malaria is a disease that has drawn worldwide attention due to the alarming rise of mortality rates particularly in third world countries. During the Plasmodium parasite intraerythrocytic life cycle, metabolic processes include the formation of hemozoin or malaria pigment. This pigment functions in the prevention of oxygen radical-mediated damage to the parasite. Drugs targeting hemozoin formation such as chloroquine and amodaquine are effective and are still used, but recently Plasmodium parasites have become resistant to these drugs, especially against chloroquine. In this study we looked at the potential use of two heterocyclic pyrimidine derivatives as anti-malaria drugs; 2,4-Diamino-6-Mercaptopyrimidine （DAMP） and 2-Mercaptopyrimidine （2-MP）. These compounds bear various coordination sites that enable them to react with metal ions to form coordination compounds. We used two methods for testing the inhibition of ferriprotoporphyrin IX （FP） biomineralisation： semi-quantitative microassay used by Deharo, and a quantitative assay used by G. Blaner and M. Akkawi. We report here the finding that （DAMP） has an in vitro inhibitory effect on I%hematin formation at concentrations and magnitude of nearly similar order to that of chloroquine, 2-MP was found to be effective but to a lower degree than DAMP.展开更多
基金supported in the context of the Italian Malaria Network by grants from Compagnia di San Paolo-IMIthe University of Torino Intramural FundsRegione Piemonte,Ricerca Sanitaria Finalizzata 2007 to PA
文摘Objective:Avidly phagocytosed hemozoin(malarial pigment) alters several functions of human monocytes and stimulates generation of several cytokines.Recently,we showed that phagocytosis of hemozoin by human monocytes increases expression and activity of matrix metalloproteinase-9,a proteolytic enzyme available in specific gelatinase granules,which contain several enzymes including lysozyme.Present work investigated active lysozyme release after phagocytosis of hemozoin and its dependence on production of tumor necrosis factor alpha. Methods:After phagocytosis of hemozoin,hemozoin-containing trophozoites or control meals(opsonized nonparasitized red blood cells and latex particles),monocyte supematants were monitored for 2 hours,in presence of blocking anti-human tumor necrosis factor alpha antibodies or recombinant human tumor necrosis factor alpha cytokine in selected experiments.Lysozyme release was evaluated by a specific spectrometric assay measuring lysozyme activity after coincubation of cell supematants with suspensions of Mycrococcus Lysodeikticus,while levels of soluble tumor necrosis factor alpha were analyzed by specific enzyme-linked immunodsorbent assay. Results:Levels of lysozyme activity and soluble tumor necrosis factor alpha protein were increased in hemozoin in-or trophozoites-laden monocytes supematants.Phagocytosis per se(control meals) also increased lysozyme release,but levels were significantly lower than those obtained after phagocytosis of hemozoin or trophozoites. Interestingly,all effects on lysozyme release observed after phagocytosis were abrogated by blocking anti-human tumor necrosis factor alpha antibodies,while they were mimicked by recombinant human tumor necrosis factor alpha cytokine.Conclusions:Present work shows that phagocytosis of hemozoin promotes monocyte degranulation and enhances active lysozyme release.The effect requires tumor necrosis factor alpha mediation.
基金supported in the context of the Italian Malaria Network by grants from Compagnia di San Paolo-IMI and from Regione Piemonte,Ricerca Sanitaria Finalizzata 2008bis to PA
文摘Objective:To investigate whether the increase of tumor necrosis factor alpha is dependent on lipidic component of malarial pigment.Methods:Adherent human monocytes were fed for 3 hours with different meals(native hemozoin;lipid free hemozoin;and control latex particles),then tumor necrosis factor alpha was monitored in cell supernatants up to 48 hours through western blotting or specific enzyme-linked immunoadsorbent assay.In selected experiments,unfed monocytes were treated with different doses of 15(S,R)-hydroxy-6,8,11,13-eicosatetraenoic acid or 4-hydroxynonenal instead of phagocytosis.Results:Hemozoin-fed monocytes produced higher levels of tumor necrosis factor alpha than unstimulated and latex-fed cells, while lipid-free hemozoin did not reproduce these results.Additionally,hemozoin effects were mimicked dose-dependently by 15(S,R)-hydroxy-6,8,11,13-eicosatetraenoic acid,but not by 4-hydroxynonenal.Conclusions:Present data suggest an essential role for lipids in hemozoindependent enhanced release of tumor necrosis factor alpha from monocytes,and 15(S,R)hydroxy -6,8,11,13-eicosatetraenoic acid could be one possible specific mediator.
基金supported by the Compagnia di San Paolo-IMI grants to MP in the context of the Italian Malaria Network
文摘More than 2 billion people are at risk of malaria,which primarily affects poor populations in tropical and subtropical areas,including Southern Asia.As malaria incidence has been reduced strongly in some parts of endemic regions by combinations of interventions,including artemisinin-based therapies and insecticide-treated bed nets,a new goal has been established recently by charity foundations which support research on malaria:the worldwide eradication of the pathology.Doing away with control approaches which have been applied for the last 50 years and more focus on elimination objectives will deeply change priorities in the area of malaria treatment,chemoprevention,vector control,vaccine research and health system assessment.In this review,actual knowledge on pathogenesis and pharmacology is discussed,and new drugs, vaccines and insecticides are described.
基金Supported by the Institute of Research and Development,Walailak University,Nakhon Si Thammarat,Thailand
文摘During malaria infection,elevated levels of pro-inflammatory mediators and nitric;oxide production have been associated with pathogenesis and disease severity.Previous in vitro and in vivo studies have proposed that both Plasmodium falciparum hemozoin and glycosylphosphatidylinositols are able to modulate blood mononuclear cells,contributing to stimulation of signal transduction and downstream regulation of the NF-KB signaling pathway,and subsequently leading to the production of pro-inflammatory cytokines,chemokines,and nitric oxide.The present review summarizes the published in vitro and in vivo studies that have investigated the mechanism of intracellular signal transduction and activation of the NF-KB signaling pathway in blood mononuclear cells after being inducted by Plasmodium falciparum malaria components.Particular attention is paid to hemozoin and glycosylphosphatidylinositols which reflect the important mechanism of signaling pathways involved in immune response.
基金supported by University of Torino Intramural Funds to GG and by grants to MP from the Compagnia di San Paolo,Torino,in the context of the Italian Malaria Network
文摘Objective:To investigate the effect of malarial pigment(hemozoin,HZ) on expression of heat shock proteins(HSPs) and cell viability in human monocytes by using a stable cell line(THP-1 cells).Methods:THP-1 cells were fed with native HZ or treated with pro-apoptotic molecule gliotoxin for 9 h.Thereafter,the protein expression of HSP-27 and HSP-70 was evaluated by western blotting.Alternatively,HZ-fed cells were cultured up to 72 h and cell viability parameters(survival,apoptosis and necrosis rates) were measured by flow cytometric analysis. Results:HZ increased basal protein levels of HSP-27 without altering those of HSP-70 in THP-1 cells,and promoted long-term cell survival without inducing apoptosis.As expected,gliotoxin inhibited HSP-27 protein expression and promoted long-term cell apoptosis.Conclusions: Present data show that HZ prevents cell apoptosis and enhances the expression of anli-apoptotic HSP-27 in THP-1 cells,confirming the previous evidences obtained from HZ-fed immunopurified monocytes.Since the use of a stable cell line is pivotal to perform HSP-27 silencing experiments, monocytic THP-1 cells could be a good candidate line for such an approach,which is heavily required to clarify the role of HSP-27 in survival of impaired HZ-fed monocytes during falciparum malaria.
文摘Malaria is one of the leading causes of mortality and morbidity in developing countries. Accurate and complete diagnosis is key for effective treatment of the disease. However, mainstream malaria diagnostic techniques suffer from a number of shortcomings. There is therefore an urgent need for development of new and more efficient techniques for malaria diagnosis. In vivo Photoacoustic spectroscopy is an emerging technique, which has great potential of delivering a nearly ideal method for early diagnosis of the disease. The technique promises to be highly sensitive and specific. In this paper, a description of photoacoustic malaria sensing is given. This is followed by a review of photoacoustic-based malaria diagnostic techniques and suggestions for future improvements.
文摘Malaria is one of the leading killer diseases in sub-Saharan Africa. Although the disease is curable, early and accurate diagnosis is key to effective therapy. Existing malaria diagnostic techniques have low detection accuracy especially when the parasite load in the blood is low. In this paper, we report on a simple photo-thermal based technique for detection of the Plasmodium parasites’ biomarker (hemozoin) in blood smear samples. The technique has demonstrated 100% Plasmodium detection sensitivity and specificity from the ten blood smear test samples used.
文摘Malaria is a disease that has drawn worldwide attention due to the alarming rise of mortality rates particularly in third world countries. During the Plasmodium parasite intraerythrocytic life cycle, metabolic processes include the formation of hemozoin or malaria pigment. This pigment functions in the prevention of oxygen radical-mediated damage to the parasite. Drugs targeting hemozoin formation such as chloroquine and amodaquine are effective and are still used, but recently Plasmodium parasites have become resistant to these drugs, especially against chloroquine. In this study we looked at the potential use of two heterocyclic pyrimidine derivatives as anti-malaria drugs; 2,4-Diamino-6-Mercaptopyrimidine （DAMP） and 2-Mercaptopyrimidine （2-MP）. These compounds bear various coordination sites that enable them to react with metal ions to form coordination compounds. We used two methods for testing the inhibition of ferriprotoporphyrin IX （FP） biomineralisation： semi-quantitative microassay used by Deharo, and a quantitative assay used by G. Blaner and M. Akkawi. We report here the finding that （DAMP） has an in vitro inhibitory effect on I%hematin formation at concentrations and magnitude of nearly similar order to that of chloroquine, 2-MP was found to be effective but to a lower degree than DAMP.
