Human Neutrophil Peptide 1 as immunotherapeutic agent against Leishmania infected BALB/c mice.

Human Neutrophil Peptide 1 (HNP1) produced by neutrophils, is a well-known antimicrobial peptide which plays a role both in innate as well as in adaptive immunity and is under intensive investigation as a potential therapeutic agent. Previous in vitro experiments have indicated the leishmaniacidal effect of recombinant HNP1 on Leishmania major (L. major) promastigotes and amastigotes. In the current study, we further extended the idea to explore the remedial effect of HNP1 in the two modalities of peptide therapy (folded HNP1) and gene therapy in L. major infected BALB/c mice. To this end, mice in five different groups received synthetic folded HNP1 (G1), pcDNA-HNP1-EGFP (G2), pcDNA-EGFP (G3), Amphotericin B (G4) and PBS (G5), which was started three weeks after infection for three consecutive weeks. Footpad swelling was monitored weekly and a day after the therapy ended, IFN-γ, IL-4, IL-10, IL-6 and nitric oxide produced by splenocytes were analyzed together with the parasite load in draining lymph nodes. Arginase activity and dermal histopathological changes were also analyzed in the infected footpads. We demonstrated that both therapeutic approaches effectively induced Th1 polarization and restricted parasite burden. It can control disease progression in contrast to non-treated groups. However, pcDNA-HNP1-EGFP is more promising in respect to parasite control than folded HNP1, but less effective than AmB treatment. We concluded with the call for a future approach, that is, a DNA-based expression of HNP1 combined with AmB as it can improve the leishmaniacidal efficacy.

Live Leishmania tarentolae secreting HNP1 as an immunotherapeutic tool against Leishmania infection in BALB/c mice.

AIM: Several disadvantages about chemotherapy for leishmaniasis has reinforced discovery of novel therapeutic agents especially immunotherapeutics. HNP1, as a member of the mammalian antimicrobial peptides family, is an attractive molecule due to its broad functional spectrum. Here, the in vivo potency of HNP1 in transgenic Leishmania tarentolae as an immunotherapy tool against Leishmania major-infected BALB/c mice was examined. METHODS & RESULTS: 3 weeks after infection with L. major, the treatment effect of L. tarentolae-HNP1-EGFP was pursued. The results were promising in respect to parasite load control and Th1 immune response polarization compared with controls. CONCLUSION: Immunotherapy by live L. tarentolae secreting HNP1 can elicit cellular immune response in a susceptible mouse model in order to control L. major infection.

Arginase activity in pathogenic and non-pathogenic species of Leishmania parasites.

Proliferation of Leishmania (L.) parasites depends on polyamine availability, which can be generated by the L-arginine catabolism and the enzymatic activity of arginase (ARG) of the parasites and of the mammalian hosts. In the present study, we characterized and compared the arginase (arg) genes from pathogenic L. major and L. tropica and from non-pathogenic L. tarentolae. We quantified the level of the ARG activity in promastigotes and macrophages infected with pathogenic L. major and L. tropica and non-pathogenic L. tarentolae amastigotes. The ARG's amino acid sequences of the pathogenic and non-pathogenic Leishmania demonstrated virtually 98.6% and 88% identities with the reference L. major Friedlin ARG. Higher ARG activity was observed in all pathogenic promastigotes as compared to non-pathogenic L. tarentolae. In vitro infection of human macrophage cell line (THP1) with pathogenic and non-pathogenic Leishmania spp. resulted in increased ARG activities in the infected macrophages. The ARG activities present in vivo were assessed in susceptible BALB/c and resistant C57BL/6 mice infected with L. major, L. tropica and L. tarentolae. We demonstrated that during the development of the infection, ARG is induced in both strains of mice infected with pathogenic Leishmania. However, in L. major infected BALB/c mice, the induction of ARG and parasite load increased simultaneously according to the time course of infection, whereas in C57BL/6 mice, the enzyme is upregulated solely during the period of footpad swelling. In L. tropica infected mice, the footpads' swellings were slow to develop and demonstrated minimal cutaneous pathology and ARG activity. In contrast, ARG activity was undetectable in mice inoculated with the non-pathogenic L. tarentolae. Our data suggest that infection by Leishmania parasites can increase ARG activity of the host and provides essential polyamines for parasite salvage and its replication. Moreover, the ARG of Leishmania is vital for parasite proliferation and required for infection in mice. ARG activity can be used as one of the main marker of the disease severity.

Mammalian host defense peptides and their implication on combating Leishmania infection.

Infection with parasites of the genus Leishmania is a health problem in many countries around the world. No effective vaccine is available against leishmaniasis, so chemotherapy is the only alternative for treatment of all forms of the disease. However, drawbacks including toxicity and severe adverse reactions restrain the use of currently available chemotherapeutics. Therefore development of new drugs and therapeutic approaches is highly demanded. Mammalian host defense peptides (mHDP) and/or mammalian antimicrobial peptides (mAMP) are among promising compounds considered effective to control the infectious diseases. These are potential multifunctional molecules that modulate the immune response besides direct killing of pathogens. Here we have reviewed the hallmark characteristics of the mHDPs in respect to the potential role they can play against leishmaniasis.

Slime layer formation and the prevalence of mecA and aap genes in Staphylococcus epidermidis isolates.

INTRODUCTION: Staphylococcus epidermidis strains are frequently associated with catheter-related infection, acute bacteremia, and hospital-acquired infection. Some isolates produce an extracellular matrix called slime that may make them more resistant to antibiotics. The aim of this study was to determine antimicrobial resistance patterns, the prevalence of slime production, and the distribution of genes (mecA and aap, respectively) associated with these phenotypes in S. epidermidis nasal isolates from health-care personnel. METHODOLOGY: A descriptive cross-sectional study was performed on 163 nasal swabs from health-care staff (one swab per subject). S. epidermidis isolates were tested for slime production on congo red agar and antibiotic resistance. PCR-based screening for mecA and aap genes was performed upon the extracted DNA of S. epidermidis isolates. RESULTS: A total of 99 S. epidermidis strains were cultured from 58.9% of the study participants (n = 96). Of these strains, 34 (34.3%) isolates produced slime. A significant relation between slime production and resistance to penicillin 32(94%) , oxacillin 30(88%), tetracycline 20(59%), erythromycin 27(79%), and clindamycin 26(77%) was found. Respectively, 95.8% and 94.8% of all isolates were PCR-positive for mecA and aap, but only 59.8% of mecA+ strains were oxacillin-resistant and 37.3% of aap+ strains were slime producers. CONCLUSIONS: The surveillance of nasal colonization with slime-forming oxacillin-resistant S. epidermidis in health-care workers might be helpful in breaking the epidemiological chain of hospital-acquired infections.