Biochemical association between essential trace elements and susceptibility to Leishmania major in BALB/c and C57BL/6 mice

Several enzymes that contribute to immune system responses require zinc and copper as trace elements for their activity. We examined zinc and copper levels in two susceptible Balb/c mouse lines and resistant C57bl/6 mice infected with Leishmania major MRHO/IR/75/ER, a prevalent strain that causes cutaneous leishmaniasis in Iran. Serum Zn and Cu were determined by flame atomic absorption spectrophotometry. Higher Cu levels were found in infected C57bl/6 mice and higher Zn levels were found in infected Balb/c mice. Also, Cu/Zn ratios were increased in both the Balb/c and the C57bl/6 mice. We conclude that concentrations of essential trace elements vary during cutaneous leishmaniasis infection and that this variation is associated with susceptibility/resistance to Leishmania major in Balb/c and C57bl/6 mice. We detected Zn deficiency in the plasma of infected Balb/c mice; possibly, therapeutic administration of Zn would be useful for treating this form of leishmaniasis. Increases in Cu level might increase resistance to leishmaniasis. Based on our findings, the Cu/Zn ratio could be a useful marker for the pathophysiology of leishmaniasis.

The ubiquitous gp63-like metalloprotease from lower trypanosomatids: in the search for a function

Plant and insect trypanosomatids constitute the "lower trypanosomatids", which have been used routinely as laboratory models for biochemical and molecular studies because they are easily cultured under axenic conditions, and they contain homologues of virulence factors from the classic human trypanosomatid pathogens. Among the molecular factors that contribute to Leishmania spp. virulence and pathogenesis, the major surface protease, alternatively called MSP, PSP, leishmanolysin, EC 3.4.24.36 and gp63, is the most abundant surface protein of Leishmania promastigotes. A myriad of functions have been described for the gp63 from Leishmania spp. when the metacyclic promastigote is inside the mammalian host. However, less is known about the functions performed by this molecule in the invertebrate vector. Intriguingly, gp63 is predominantly expressed in the insect stage of Leishmania, and in all insect and plant trypanosomatids examined so far. The gp63 homologues found in lower trypanosomatids seem to play essential roles in the nutrition as well as in the interaction with the insect epithelial cells. Since excellent reviews were produced in the last decade regarding the roles played by proteases in the vertebrate hosts, we focused in the recent developments in our understanding of the biochemistry and cell biology of gp63-like proteins in lower trypanosomatids.

Tripanossomatídeos de insetos e de plantas são informalmente denominados de "tripanossomatídeos inferiores". Estes microrganismos são utilizados rotineiramente como modelos para estudos de bioquímica e de biologia molecular porque são facilmente cultivados sob condições axênicas e porque possuem homólogos aos fatores de virulência encontrados nos tripanossomatídeos que são patógenos humanos clássicos. Dentre os fatores moleculares que contribuem para a virulência e patogênese de Leishmania spp. destaca-se a principal protease de superfície, também conhecida como MSP, PSP, leishmanolisina, EC 3.4.24.36 e gp63, que é a proteína de superfície mais abundante encontrada nas formas promastigotas de Leishmania. Diversas funções foram descritas para a gp63 de Leishmania no hospedeiro vertebrado. Entretanto, pouco é conhecido sobre as funções desempenhadas por essa molécula no inseto vetor. Curiosamente, a gp63 é predominantemente expressa na forma evolutiva de Leishmania encontrada no inseto, e em todos os tripanossomatídeos de insetos e plantas analisados até o presente momento. Os homólogos da gp63 presentes nos tripanossomatídeos inferiores desempenham um papel essencial na nutrição assim como na interação com as células epiteliais do inseto. Uma vez que revisões de excelente qualidade foram produzidas na última década sobre a função de proteases nos hospedeiros vertebrados, nesta revisão nós abordamos os recentes progressos sobre os aspectos bioquímicos e as prováveis funções biológicas desempenhadas pelas proteínas homólogas à gp63 nos tripanossomatídeos inferiores.

Comparative effect of ion calcium and magnesium in the activation and infection of the murine macrophage by Leishmania major

Amastigotes of Leishmania major have a great ability to evade destruction in host cells. This study investigated the activation in resident, inflammatory macrophages and J774 cells in vitro treated with lipopolysaccharide (LPS), soluble Leishmania antigen (SLA), calcium ionophore (CaI) and magnesium (Mg2+) alone or combined. An increase in nitric oxide (NO) production was observed in J774 or inflammatory macrophages treated with LPS alone or in combination with SLA and CaI. The same treatments did not affect the NO release by resident macrophages. There was no interference in uptake of L. major but CaI decreased intracellular proliferation of the parasite. This study demonstrated the importance of CaI in decreasing L. major proliferation inside murine macrophages while Mg2+ seemed to increase parasite proliferation. These finding may help to understand the events involved in host cells' clearance of this pathogen..

Histopathological study of three leishmania major strains

Amastigotes count in inoculated foot pad and histopathological study of infected mice were performed to study three Leishmania major strains: the Senegalese strain MHOM/SN/00/DKI[SN], the Sudanese strain MHOM/SD/89/UG8[SD], and the Saudi strain MHOM/SA/84/JISH[SA]. Eight-week-old male BALB/c mice were divided into three groups. Each group was infected with one of the studied strains. Amastigotes in the inoculated foot of infected. mice in the three groups were counted at 30 and 45 days using modified fluorescence diacetate/ethidium bromide viability test. The number of amastigotes in the SA group was found to be significantly lower than that of the other two groups at both durations. There was no significant difference between the number of amastigotes in the SN and SD strains at 30 days. but it was significantly higher in the SN group than that of the SD group at 45 days post-inoculation. In the animals studied, tissue samples were obtained from the skin, liver, spleen, and testes for gross pathological changes and histopathological evaluation. The SD strain started earlier and led a more aggressive course. The SN and SA strains were less aggressive. The SA strain showed changes at an earlier time and resulted in a more aggressive course of the disease. The SN and SA strains were less aggressive. The SA strain showed the most chronic course of the three

Psammomys obesus cretzschmar, 1828 and zoonotic cutaneous leishmaniasis in Sinai peninsula, Egypt

In the Middle East, the fat sand rat Psammomys obesus is the most important reservoir host of zoonotic cutaneous leishmaniasis [ZCL]. It is the most incriminated host in outbreaks. Two P. obesus caught in Wadi El-Gedeiret [El-Arish, North Sinai] were found naturally infected with Leishmania major as indicated by enzyme electrophoresis. In Egypt, the already known reservoir hosts are Gerbillus pyramidum I, Geoffroy St. Hilaire, 1825, Meriones crassus Sundevall, 1984 and Meriones sacramnti Thomas, 1922. The role of P. obesus as a host was discussed

Studies on the causative agent of cutaneous leishmaniasis in Shiraz Iran

Leishmania species were isolated from 14 patients with acute cutaneous leishmaniasis [CL] in Shiraz. The isolated organisms were injected subcutaneously into the base tail of 14 groups of Swiss outbred white mice. Each group consisted of 10 mice and each mouse received 2xl0 promastigotes. During 4-6 weeks after inoculation, smears and cultures were taken from this site and the isolated organisms were inoculated into a new series of mice. During 6-8 weeks after inoculation, erythema was observed in only two groups of these animals. No ulceration or open lesion, which are characteristics of L. major, were noticed in the inoculated mice. Upon direct smear preparation from these two groups of animals only a few organisms were seen with no growth in cultures. On the basis of these observations we concluded that the Leishmania isolated from the patients with acute CL in Shiraz is Leishmania tropica. Various factors which contribute to the survival of the organisms at the site of inoculation without formation of open lesions are discussed

Phosphorylation of proteins in virulent promastigotes from Leishmania major

Protein kinases are present in the plasma membrane of the human parasite Leishmania. A marked increase in enzyme activity has been detected as cultures entered into the stationary phase of growth. Since avirulent parasites can be separated from virulent forms by the peanut agglutinin (PNA), we have examined the change in the protein kinase activity of L. major during growth in vitro and the difference in phosphorylation with virulent promastigotes (PNA-) of L. major. Marked similarities were found between the phosphorylation patterns of the logarithmic and stationary phase promastigotes of L. major. On the other hand, when the phosphorylation pattern of those proteins, shared by both the metacyclic (PNA-) promastigotes and the stationary phase cells, was examined, a marked increase in both the total number of phosphoproteins and the extent of their phosphorylation was observed in PNA-. Both the increase in protein kinase activity in the stationary phase parasites and the marked changes in phosphorylation in the highly infective promastigotes, may provide a clue as to the adaptative mechanism which enable promastigotes to survive within the vertebrate host