Transcriptional Shift and Metabolic Adaptations during Leishmania Quiescence Using Stationary Phase and Drug Pressure as Models

Microorganisms can adopt a quiescent physiological condition which acts as a survival strategy under unfavorable conditions. Quiescent cells are characterized by slow or non-proliferation and a deep downregulation of processes related to biosynthesis. Although quiescence has been described mostly in bacteria, this survival skill is widespread, including in eukaryotic microorganisms. In Leishmania, a digenetic parasitic protozoan that causes a major infectious disease, quiescence has been demonstrated, but the molecular and metabolic features enabling its maintenance are unknown. Here, we quantified the transcriptome and metabolome of Leishmania promastigotes and amastigotes where quiescence was induced in vitro either, through drug pressure or by stationary phase. Quiescent cells have a global and coordinated reduction in overall transcription, with levels dropping to as low as 0.4% of those in proliferating cells. However, a subset of transcripts did not follow this trend and were relatively upregulated in quiescent populations, including those encoding membrane components, such as amastins and GP63, or processes like autophagy. The metabolome followed a similar trend of overall downregulation albeit to a lesser magnitude than the transcriptome. It is noteworthy that among the commonly upregulated metabolites were those involved in carbon sources as an alternative to glucose. This first integrated two omics layers afford novel insight into cell regulation and show commonly modulated features across stimuli and stages.

Trichilianones A-D, Novel Cyclopropane-Type Limonoids from Trichilia adolfi

The fractionation of an ethanol extract of the bark of Trichilia adolfi yielded four novel limonoids (trichilinones A-D, 1–4), with five fused rings and related to the hortiolide-type limonoids. Starting with an ε-lactone, which is α,β-unsaturated in trichilinones A and D (1 and 4), attached to a tetrahydrofuran ring that is connected to an unusual bicyclo [5.1.0] hexane system, joined with a cyclopentanone with a 3-furanyl substituent [(2-oxo)-furan-(5H)-3-yl in trichilinone D (4)], the four compounds isolated display a new 7/5/3/5/5 limonoid ring system. Their structures were established based on extensive analysis of NMR spectroscopic data. As the crude extract possessed anti-leishmanial properties, the compounds were assayed for cytotoxic and anti-parasitic activities in vitro in murine macrophages cells (Raw 264.7) and leishmania promastigotes (L. amazoniensis and L. braziliensis), respectively. The compounds showed moderate cytotoxicity (approximately 70 μg/mL), but are not responsible for the leishmanicidal effect of the extract.

Photodynamic activity of Photogem® in Leishmania promastigotes and infected macrophages

Objectives: This study aimed to evaluate the effect of photodynamic therapy (PDT) with Photogem® in promastigotes of Leishmania braziliensis and Leishmania major, and in infected macrophages. Materials & methods: The following parameters were analyzed: Photogem® internalization, mitochondrial activity, viability, tubulin marking and morphological alterations in promastigotes and viability in infected macrophages. Results: Photogem® accumulated in the cytosol and adhered to the flagellum. Changes were observed in the mitochondrial activity in groups maintained in the dark, with no viability alteration. After PDT, viability decreased up to 80%, and morphology was affected. Conclusion: The results point out that PDT with Photogem® can reduce parasite and macrophage viability.

Antileishmanial potential of alkaloids isolated from plants: an integrative review

Leishmaniasis treatment is often carried out with drugs of high toxic potential and high cost, and satisfactory therapeutic response is not usually observed. In this context, searching for therapeutic alternatives is urgent. This study seeks to evaluate the antileishmanial potential of alkaloids from plants. The search for scientific papers occurred at Pubmed, CAPES Journal Portal (PPC), Virtual Health Library (VHL) and COCHRANE using the descriptors: alkaloid and antileishmanial. The inclusion criteria were studies about alkaloids isolated from plants and tested against Leishmania parasite. A total of 805 publications were found in Pubmed, 825 in PPC, 4 in VHL and none in COCRHANE. After reading the titles and abstracts, articles containing other biological evaluations (350), chemical studies such as docking and material characterizations (388), evaluation of extracts and fractions activities (406) which did not fit in this research or were in duplicate (377) were excluded. Acridone and all the naphthylisoquinolinic and tetrahydroisoquinolinic alkaloids were active or moderately active against Leishmania promastigotes or amastigotes, and indolizidine was active against both forms. The β-carbolines were inactive or moderately active against Leishmania promastigotes, with the exception of flavopereirine. The indolizidine alkaloid was the most promising as a future drug candidate, since it was very active against both forms of Leishmania.

Super Infection of Cutaneous Leishmaniasis Caused by Leishmania major and L. tropica to Crithidia fasciculata in Shiraz, Iran

Background: The aims of the current study were to determined present status of CL in Shiraz City, identify the causative species of Leishmania and conduct phylogenetic evaluations in detected parasites. Methods: This study was conducted on 70 individuals with suspected CL that referred to the major health centers of Shiraz (Valfajr), Fars province, Iran, from Sep 2016 to Jul 2017. DNA was extracted from cultured Leishmania promastigotes and PCR-RFLP were performed using ITS1-rDNA gene. Results: Overall, 39 male (55.70%) and 31 (44.30%) female were found to be positive microscopically. All of direct examined positive samples were confirmed to be positive for Leishmania spp. DNA. Based upon the PCRRFLP patterns and phylogenetic analysis, 46 (65.72%), 17 (24.28%) and 7 (10%) isolates were clearly identified as L. major, L. tropica and C. fasciculata, respectively. Conclusion: The dominat detected species in Shiraz City was L. major and L. tropica, respectively. CL has high prevalence in Shiraz City; therefore, more studies on leishmaniasis in the natural vectors and also reservoirs infection in this region is exceedingly recommended. Skin leisons due to C. fasciculata, was described for the first time in Iran (Shiraz City).

Entomological Survey for the Detection of Sand Fly Fauna and Vector Species in the Cutaneous Leishmaniasis Endemic Area in East Mediterranean Region of Turkey, Mersin Province

Cutaneous (CL) and visceral (VL) forms of leishmaniasis, transmitted by sand flies, are seen in all countries located in Mediterranean Basin including Turkey. In this study, we aimed to conduct an entomological survey for the detection of sand fly fauna and vector species in Mersin province, one of the important endemic areas for CL in Turkey. In total, 912 sand fly specimens were collected in 2010 and 2011 using CDC light traps. Nine Phlebotomus (Diptera: Psychodidae) and three Sergentomyia (Diptera: Psychodidae) species were detected. Of the collected Phlebotomus sand flies, P. sergenti Parrot, 1917 (30.1%) was the most dominant followed by P. alexandri Sinton, 1928 (18.2%), P. neglectus/syriacus Tonnoir Adler (12.0%), P. tobbi Adler & Theodor, 1930 (11.7%), and P. papatasi Scopoli, 1786 (10.2%), while S. minuta Rondani, 1843 (11.3%) was the dominant species among Sergentomyia. During the field work in 2011, female specimens (n = 81) were screened for the presence of Leishmania promastigotes by midgut dissection, and all were found negative. The rest of the collected female specimens (n = 334) were pooled according to species (P. alexandri, P. neglectus/syriacus, P. papatasi, P. sergenti, P. simici, and P. tobbi) and location (Mut, Silifke, and Anamur). In total, 29 pools were generated and real-time ITS1 PCR assay was performed to detect and identify natural Leishmania Ross, 1903 (Kinetoplastida: Trypanosomatida) infection. Two pools, both from Mut town, containing P. sergenti specimens were found positive and Leishmania tropica Ross, 1903 was identified as an infectious agent for both pools. In conclusion, the sand fly fauna was determined in an endemic area for CL. The detection of L. tropica DNA in P. sergenti specimens showed the possible vectorial role of this species in Mersin province.

Transmission of Leishmania infantum from cats to dogs

Leishmania infantum infection in cats has been reported in several countries, including Brazil. However, the transmission of visceral leishmaniasis (VL) from cats to another host has not been proven yet. Therefore, the aim of this study was to verify the possibility of L. infantum transmission from cats to dogs. In order to verify the possibility of VL transmission from the cat to the dog, xenodiagnosis was carried out in a VL-positive cat, using 55 female Lutzomyia longipalpis. Five days later, 40 insects were dissected to verify Leishmania infection. The remaining 15 females were fed in a healthy dog. The potential infection of the dog was verified through clinical, serological, parasitological examinations, and PCR, at three, six, and twelve months post-infection. All 55 L. longipalpis females became visibly engorged. Leishmania promastigotes were detected in 27.5% of the dissected insects. Leishmania infection in the dog was confirmed upon first evaluation. DNA sequencing of the parasite isolated from the cat confirmed L. infantum infection and showed 99% similarity with the L. infantum DNA sequences from the dogs. Through this study, it was possible to confirm the L. infantum experimental transmission from a domestic cat to a domestic dog through its biological vector L. longipalpis.