Synthetic Plasmodium-like hemozoin activates the immune response: a morphology - function study.

Increasing evidence points to an important role for hemozoin (HZ), the malaria pigment, in the immunopathology related to this infection. However, there is no consensus as to whether HZ exerts its immunostimulatory activity in absence of other parasite or host components. Contamination of native HZ preparations and the lack of a unified protocol to produce crystals that mimic those of Plasmodium HZ (PHZ) are major technical limitants when performing functional studies with HZ.

Autofluorescence of condensed heme aggregates in malaria pigment and its synthetic equivalent hematin anhydride (beta-hematin).

The condensed crystalline phase of iron(III) protoporphyrin IX either isolated from parasite culture as malaria pigment (hemozoin) or synthetic equivalent hematin anhydride exhibits a solid-state autofluorescence characterized by an excitation maximum of 555 nm and an emission maximum of 577 nm. The excitation spectrum maximum at 555 nm corresponds to the Q(0,0) band in the absorption spectrum which represents the lowest singlet of the material. This suggests that the fluorescent emission is due to the heme condensed phase.

A novel form of NF-kappaB is induced by Leishmania infection: involvement in macrophage gene expression.

Leishmania spp. are obligate intracellular parasites that inhabit the phagolysosomes of macrophages. Manipulation of host cell signaling pathways and gene expression by Leishmania is critical for Leishmania's survival and resultant pathology.

Hemozoin induces macrophage chemokine expression through oxidative stress-dependent and -independent mechanisms.

Chemokine production has been associated with the immunopathology related to malaria. Previous findings indicated that hemozoin (HZ), a parasite metabolite released during schizogeny, might be an important source of these proinflammatory mediators. In this study we investigated the molecular mechanisms underlying HZ-inducible macrophage (Mphi) chemokine mRNA expression.

Signaling events involved in macrophage chemokine expression in response to monosodium urate crystals.

Chemokine production has been associated with leukocyte infiltration into the joint during gouty arthritis, and monosodium urate (MSU) crystals, the causative agent of this arthropathy, have been shown to modulate their expression. In the present study, we investigated the transductional mechanisms underlying this cellular regulation in the murine macrophage cell line B10R. We report that MSU crystals rapidly and transiently increase mRNA levels of various chemokines in a concentration-dependent manner.