Introduction. In the last decade growing evidence in vitro and in vivo on matrix metalloproteinases (MMPs) involvement in malaria has been emerging. Haemozoin (HZ, malaria pigment) was shown to enhance MMP-9 activity in human monocytes, whereas high serum levels of Tissue Inhibitor of Metalloproteinase-1 (TIMP-1), endogenous MMP-9 inhibitor, were found in patients with severe malaria. Here, the effects of HZ on TIMP-1 expression and release by human monocytes were studied, along with dependence on production of Macrophage Inflammatory Protein-1(MIP-1)alpha and involvement of NF-kappaB activation. Methods. Human adherent monocytes from peripheral blood were fed with latex (control meal) or HZ and further incubated with: rhMIP-1alpha; anti-hMIP-1alpha blocking Abs; quercetin; artemisinin; and parthenolide. Therefore, TIMP-1/MIP-1alpha mRNA expression was evaluated by Real Time RT-PCR; TIMP-1/MIP-1alpha protein release by Western blotting and ELISA; total net gelatinolytic activity by fluorogenic gelatin conversion assay. Results. HZ enhanced TIMP-1 and MIP-1alpha mRNA expression and protein release, whereas latex did not. All the HZ effects on TIMP-1 were mimicked by rhMIP-1alpha and abrogated by anti-hMIP-1alpha Abs. Quercetin, artemisinin and parthenolide, three NF-kappaB inhibitors showing antimalarial properties, abrogated the HZ effects on MIP-1alpha/TIMP-1 release. The total gelatinolytic activity, representing the net sum of MMP-9 activity and TIMP-1 inhibition, was enhanced by HZ. Conclusions. Phagocytosis of HZ by human monocytes promotes MIP-1alpha-dependent increase of TIMP-1 expression and release through NF-kappaB activation. The present data fit with previous evidence indicating TIMP-1 as a marker for severe malaria; however, since TIMP-1 enhancement is not sufficient to inhibit the HZ-increased MMP-9 activity, future studies aimed to define feasibility of adjuvant therapy with supplementary synthetic MMP inhibitors are strongly encouraged.
Phagocytosis of haemozoin alters MMP-9/TIMP-1 balance in human monocytes: role of cytokines, lipids and NF-kappaB
GIRIBALDI, Giuliana;VALENTE, Elena;POLIMENI, Manuela;ULLIERS, Daniela;KHADJAVI, AMINA;MANDILI, GIORGIA;PRATO, Mauro
2011-01-01
Abstract
Introduction. In the last decade growing evidence in vitro and in vivo on matrix metalloproteinases (MMPs) involvement in malaria has been emerging. Haemozoin (HZ, malaria pigment) was shown to enhance MMP-9 activity in human monocytes, whereas high serum levels of Tissue Inhibitor of Metalloproteinase-1 (TIMP-1), endogenous MMP-9 inhibitor, were found in patients with severe malaria. Here, the effects of HZ on TIMP-1 expression and release by human monocytes were studied, along with dependence on production of Macrophage Inflammatory Protein-1(MIP-1)alpha and involvement of NF-kappaB activation. Methods. Human adherent monocytes from peripheral blood were fed with latex (control meal) or HZ and further incubated with: rhMIP-1alpha; anti-hMIP-1alpha blocking Abs; quercetin; artemisinin; and parthenolide. Therefore, TIMP-1/MIP-1alpha mRNA expression was evaluated by Real Time RT-PCR; TIMP-1/MIP-1alpha protein release by Western blotting and ELISA; total net gelatinolytic activity by fluorogenic gelatin conversion assay. Results. HZ enhanced TIMP-1 and MIP-1alpha mRNA expression and protein release, whereas latex did not. All the HZ effects on TIMP-1 were mimicked by rhMIP-1alpha and abrogated by anti-hMIP-1alpha Abs. Quercetin, artemisinin and parthenolide, three NF-kappaB inhibitors showing antimalarial properties, abrogated the HZ effects on MIP-1alpha/TIMP-1 release. The total gelatinolytic activity, representing the net sum of MMP-9 activity and TIMP-1 inhibition, was enhanced by HZ. Conclusions. Phagocytosis of HZ by human monocytes promotes MIP-1alpha-dependent increase of TIMP-1 expression and release through NF-kappaB activation. The present data fit with previous evidence indicating TIMP-1 as a marker for severe malaria; however, since TIMP-1 enhancement is not sufficient to inhibit the HZ-increased MMP-9 activity, future studies aimed to define feasibility of adjuvant therapy with supplementary synthetic MMP inhibitors are strongly encouraged.
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