Tumor necrosis factor-α\alpha in combination with interferon-γ\gamma, but not with interleukin 4 activates murine macrophages for elimination of Leishmania major amastigotes

We have previously shown that during an infection with Leishmania major, susceptible BALB/c mice, as opposed to mice of a resistant strain (C57BLl6), are primed by lipopolysaccharide for the production of high levels of tumor necrosis factor-$\alpha$ (TNF-$\alpha$) which is known to be a potent maerophage M$\Phi$ stimulator in other parasitic diseases. In the present study we investigated whether TNF-$\alpha$ activates M$\Phi$ for killing of L. major parasites. In the absence of interferon-y (IFN-$\gamma$) or lipopolysaccharide, TNF-$\alpha$ (0.025-25000 U/ml) failed to activate peritoneal exudate M$\Phi$ from BALB/c mice for killling of L. major amastigotes. In the presence of suboptimal doses of IFN-$\gamma$ (5 or 10 Vlml), however, TNF-$\alpha$ mediated a rapid elimination of intracellular parasites, which was highly significant compared to IFN-$\gamma$ alone. Tbe combination of TNF with interleukin 4, in contrast, was inactive in this respect and allowed survival of intracellular parasites. From these data we conelude that the presence of IFN-$\gamma$ is crucial for TNF-$\alpha$-mediated killing of L. major parasites by M$\Phi$. Disease progression in susceptible mice therefore seems to be a consequence of a deficiency of IFN-$\gamma$ and a predominance of interleukin 4 rather than the result of an excess amount of TNF-$\alpha$

Antileishmanial Potential of Crude Plant Extracts Derived from Medicinal Plants in Palestine

Herbal and traditional medicine is commonly and widely used in Palestine. There has been no ethno pharmacological study to document the usefulness of traditional or medicinal plants from Palestine against leishmaniasis, a spectrum of severe parasitic diseases that occur worldwide and is caused by protozoa of the genus Leishmania. The aim of the present study was to collect and analyze some of the traditionally used medicinal plants from Palestine against Leishmania major parasites that cause cutaneous leishmaniasis. Plant materials were collected during spring and summer of the year 2011, identified and the voucher numbers were kept at Al-Quds University Gardens (AQUG). The whole plant (except roots), flowers, fruits or seeds were collected, washed with distilled water, air dried in the shade for 20 days and then powdered in an electric grinder. For each plant species, alcoholic and dimethyl sulfoxide extracts were tested in vitro against L. major promastigotes and their antileishmanial activities were evaluated by Alamar Blue bioassay. Twenty plant species belonging to14 families were examined for their in vitro anti-parasitic effect against L. major. Among the total crude extracts tested; five were found to have various levels of activities (20%), some extracts having significant antileishmanial activity with IC50 values ranging from 8.83 to 100 μg/mL. The most active crude extracts were from the shoots of Artemisia inculta and Malva sylvestris with activity of 84.1%, IC50 = 8.8 μg/mL. And 90.1%, IC50 = 19.5 μg/mL respectively. The results demonstrate that the crude extracts of Artemisia inculta and Malva sylvestris showed promising antileishmanial activity, further and extensive studies should be carried out; particularly bio-guided fractionation to identify the active fraction and further chemical characterization of structureThe authors gratefully thank the Deutscher Akademischer Austauschdienst (DAAD) and Zamallah program for providing travel grant. IMIB - Institute for Molecular Infection Biology, for providing support to validate this work at Würzburg University, financial support by the Deutsche Forschungsgemeinschaft (SFB 630) given To HM is gratefully acknowledge

Anti-Parasitic Compounds from Streptomyces sp. Strains Isolated from Mediterranean Sponges

Actinomycetes are prolific producers of pharmacologically important compounds accounting for about 70% of the naturally derived antibiotics that are currently in clinical use. In this study, we report on the isolation of Streptomyces sp. strains from Mediterranean sponges, on their secondary metabolite production and on their screening for anti-infective activities. Bioassay-guided isolation and purification yielded three previously known compounds namely, cyclic depsipeptide valinomycin, indolocarbazole alkaloid staurosporine and butenolide. This is the first report of the isolation of valinomycin from a marine source. These compounds exhibited novel anti-parasitic activities specifically against Leishmania major (valinomycin IC50 < 0.11 μM; staurosporine IC50 5.30 μM) and Trypanosoma brucei brucei (valinomycin IC50 0.0032 μM; staurosporine IC50 0.022 μM; butenolide IC50 31.77 μM). These results underscore the potential of marine actinomycetes to produce bioactive compounds as well as the re-evaluation of previously known compounds for novel anti-infective activities

Pathogen- and Host-Directed Antileishmanial Effects Mediated by Polyhexanide (PHMB)

BACKGROUND:Cutaneous leishmaniasis (CL) is a neglected tropical disease caused by protozoan parasites of the genus Leishmania. CL causes enormous suffering in many countries worldwide. There is no licensed vaccine against CL, and the chemotherapy options show limited efficacy and high toxicity. Localization of the parasites inside host cells is a barrier to most standard chemo- and immune-based interventions. Hence, novel drugs, which are safe, effective and readily accessible to third-world countries and/or drug delivery technologies for effective CL treatments are desperately needed. METHODOLOGY/PRINCIPAL FINDINGS:Here we evaluated the antileishmanial properties and delivery potential of polyhexamethylene biguanide (PHMB; polyhexanide), a widely used antimicrobial and wound antiseptic, in the Leishmania model. PHMB showed an inherent antileishmanial activity at submicromolar concentrations. Our data revealed that PHMB kills Leishmania major (L. major) via a dual mechanism involving disruption of membrane integrity and selective chromosome condensation and damage. PHMB's DNA binding and host cell entry properties were further exploited to improve the delivery and immunomodulatory activities of unmethylated cytosine-phosphate-guanine oligodeoxynucleotides (CpG ODN). PHMB spontaneously bound CpG ODN, forming stable nanopolyplexes that enhanced uptake of CpG ODN, potentiated antimicrobial killing and reduced host cell toxicity of PHMB. CONCLUSIONS:Given its low cost and long history of safe topical use, PHMB holds promise as a drug for CL therapy and delivery vehicle for nucleic acid immunomodulators

Dendritic cell-mediated vaccination relies on interleukin-4 receptor signaling to avoid tissue damage after Leishmania major infection of BALB/c mice

Prevention of tissue damages at the site of Leishmania major inoculation can be achieved if the BALB/c mice are systemically given L. major antigen (LmAg)-loaded bone marrow-derived dendritic cells (DC) that had been exposed to CpG-containing oligodeoxynucleotides (CpG ODN). As previous studies allowed establishing that interleukin-4 (IL-4) is involved in the redirection of the immune response towards a type 1 profile, we were interested in further exploring the role of IL-4. Thus, wild-type (wt) BALB/c mice or DC-specific IL-4 receptor alpha (IL-4Rα)-deficient (CD11ccreIL-4Rα−/lox) BALB/c mice were given either wt or IL-4Rα-deficient LmAg-loaded bone marrow-derived DC exposed or not to CpG ODN prior to inoculation of 2×105 stationary-phase L. major promastigotes into the BALB/c footpad. The results provide evidence that IL4/IL-4Rα-mediated signaling in the vaccinating DC is required to prevent tissue damage at the site of L. major inoculation, as properly conditioned wt DC but not IL-4Rα-deficient DC were able to confer resistance. Furthermore, uncontrolled L. major population size expansion was observed in the footpad and the footpad draining lymph nodes of CD11ccreIL-4Rα−/lox mice immunized with CpG ODN-exposed LmAg-loaded IL-4Rα-deficient DC, indicating the influence of IL-4Rα-mediated signaling in host DC to control parasite replication. In addition, no footpad damage occurred in BALB/c mice that were systemically immunized with LmAg-loaded wt DC doubly exposed to CpG ODN and recombinant IL-4. We discuss these findings and suggest that the IL4/IL4Rα signaling pathway could be a key pathway to trigger when designing vaccines aimed to prevent damaging processes in tissues hosting intracellular microorganisms

Development of helper T cell subsets: a central role for interleukin 12

No abstract availabl

Experimental cutaneous leishmaniasis: Langerhans cells internalize Leishmania major and induce an antigen-specific T-cell response.

No abstract availabl

Epidermal Langerhans cells are critical for immunoregulation of cutaneous leishmaniasis

In leishmaniasis, macrophages are known to play a central role as modulators of the specific immune activity. In this article, Heidrun Moll presents evidence for the critical involvement of another component of the skin immune system, the epidermal Langerhans cell. She proposes that Langerhans cells take up parasites in the skin and transport them to the draining lymph node for presentation to T cells and initiation of the specific immune response

L3T4+ T cells promoting susceptibility to murine cutaneous leishmaniasis express the surface marker Ly-24 (Pgp-1)

No abstract availabl

Simultaneous demonstration of two antigens with immunogold-silver staining and immunoenzymatic labeling

A novel technique for independent and simultaneous labeling of two antigens expressed on individual cells (referred to as mixed labeling) is presented. The staining procedure combined three-step (streptavidin-biotin) immunogold-silver staining with three-step immunoenzymatic labeling. To ensure both high specificity and high sensitivity, particular emphasis was placed on designing a protocol that avoids immunological crossreactivity between the antibody reagents and overlapping of the final color products. Two examples for usage of this mixed labeling technique are described: lymphocyte subpopulations were identified in inflammatory lesions of human skin and infected host cells were characterized in the skin of mice infected with the obligatory intracellular parasite Leishmania major, a cause of human cutaneous leishmaniasis