Leishmaniasis is a parasitic disease caused by hemoflagellate, Leishmania spp. The parasite is transmitted by the bite of an infected female phlebotomine sandfly. The disease is prevalent throughout the world and in at least 88 countries. Nearly 25 compounds are reported to have anti-leishmanial effects but not all are in use. The pentavalent antimony compounds have remained mainstay for nearly 75 years. Pentavalent antimony is a prodrug that is reduced by glutathione to active trivalent species catalyzed by thiol-dependent-reductase. However, emergence of resistance led to the use of other compounds--amphotericin B, pentamidine, paromomycin, allopurinol etc. Amphotericin B, an antifungal macrolide polyene is characterized by the hydrophilic polyhydroxyl and hydrophobic polyene faces on it long axis. Presently, it is the only drug with highest cure rate. It acts on membrane sterols resulting in parasite cell lysis. Its lipid formulations have been developed to minimize side effects. Other anti-fungals like ketoconazole, fluconazole and terbinafine are found less effective. Recently, anticancer alkylphosphocholines have been found most effective oral compounds. These act as membrane synthetic ether-lipid analogues, and consist of alkyl chains in the lipid portions. Most promising of these are miltefosine (hexadecylphosphocholine), edelfosine (ET-18-OCH(3)) and ilmofosine (BM 41.440). However, the recent focus has been on identifying newer therapeutic targets in the parasite such as DNA topoisomerases. The present review describes the current understanding of different drugs against leishmaniasis, their chemistry, mode of action and the mechanism of resistance in the parasite. Future perspectives in the area of new anti-leishmanial drug targets are also enumerated. However, due to the vastness of the topic main emphasis is given on visceral leishmaniasis.
Leishmaniasis is a vector-borne disease caused by different species of protozoan parasites of the genus Leishmania. It is a major health problem yet neglected tropical diseases, with approximately 350 million people worldwide at risk and more than 1.5 million infections occurring each year. Leishmaniasis has different clinical manifestations, including visceral (VL or kala-azar), cutaneous (CL), mucocutaneous (MCL), diffuse cutaneous (DCL) and post kala-azar dermal leishmaniasis (PKDL). Currently, the only mean to treat and control leishmaniasis is by rational medications and vector control. However, the number of available drugs is limited and even these are either exorbitantly priced, have toxic side effects or prove ineffective due to the emergence of resistant strains. On the other hand, the vector control methods are not so efficient. Therefore, there is an urgent need for developing a safe, effective, and affordable vaccine for the prevention of leishmaniasis. Although in recent years a large body of researchers has concentrated their efforts on this issue, yet only three vaccine candidates have gone for clinical trial, until date. These are: (i) killed vaccine in Brazil for human immunotherapy; (ii) live attenuated vaccine for humans in Uzbekistan; and (iii) second-generation vaccine for dog prophylaxis in Brazil. Nevertheless, there are at least half a dozen vaccine candidates in the pipeline. One can expect that, in the near future, the understanding of the whole genome of Leishmania spp. will expand the vaccine discovery and strategies that may provide novel vaccines. The present review focuses on the development and the status of various vaccines and potential vaccine candidates against leishmaniasis.
Aims: Mitochondrial Ca 2+ homeostasis is crucial for balancing cell survival and death. The recent discovery of the molecular identity of the mitochondrial Ca 2+ uniporter pore (MCU) opens new possibilities for applying genetic approaches to study mitochondrial Ca 2+ regulation in various cell types, including cardiac myocytes. Basal tyrosine phosphorylation of MCU was reported from mass spectroscopy of human and mouse tissues, but the signaling pathways that regulate mitochondrial Ca 2+ entry through posttranslational modifications of MCU are completely unknown. Therefore, we investigated a 1 -adrenergic-mediated signal transduction of MCU posttranslational modification and function in cardiac cells. Results: a 1 -adrenoceptor (a 1 -AR) signaling translocated activated proline-rich tyrosine kinase 2 (Pyk2) from the cytosol to mitochondrial matrix and accelerates mitochondrial Ca 2+ uptake via Pyk2-dependent MCU phosphorylation and tetrametric MCU channel pore formation. Moreover, we found that a 1 -AR stimulation increases reactive oxygen species production at mitochondria, mitochondrial permeability transition pore activity, and initiates apoptotic signaling via Pyk2-dependent MCU activation and mitochondrial Ca 2+ overload. Innovation: Our data indicate that inhibition of a 1 -AR-Pyk2-MCU signaling represents a potential novel therapeutic target to limit or prevent mitochondrial Ca 2+ overload, oxidative stress, mitochondrial injury, and myocardial death during pathophysiological conditions, where chronic adrenergic stimulation is present. Conclusion: The a 1 -AR-Pyk2-dependent tyrosine phosphorylation of the MCU regulates mitochondrial Ca 2+ entry and apoptosis in cardiac cells. Antioxid. Redox Signal. 21, 863-879.
BackgroundMiltefosine unresponsive and relapse cases of visceral leishmaniasis (VL) are increasingly being reported. However, there has been no laboratory confirmed reports of miltefosine resistance in VL. Here, we report two laboratory confirmed cases of VL from India.MethodsTwo patients with VL were referred to us with suspected VL. The first patient was a native of the VL endemic state of Bihar, but residing in Delhi, a VL non-endemic area. He was treated with broad-spectrum antibiotics and antipyretics but was unresponsive to treatment. The second patient was from Jharkhand state in eastern India (adjoining Bihar), another endemic state for VL. He was refractory to anti-leishmanial treatment, which included administration of miltefosine. Following investigation, both patients were serologically positive for VL, and blood buffy coat from both patients grew Leishmania donovani. The isolates derived from both cases were characterized for their drug susceptibility, genetically characterised, and SNPs typed for LdMT and LdROS gene expression. Both patients were successfully treated with amphotericin B.ResultsThe in vitro drug susceptibility assays carried out on both isolates showed good IC50 values to amphotericin B (0.1 ± 0.0004 μg/ml and 0.07 ± 0.0019 μg/ml). One isolate was refractory to SbIII with an IC50 of > 200 μM while the second isolate was sensitive to SbIII with an IC50 of 36.70 ± 3.2 μM. However, in both the isolates, IC50 against miltefosine was more than 10-fold higher (> 100 μM) than the standard strain DD8 (6.8 ± 0.1181 μM). Furthermore, genetic analyses demonstrated single nucleotide polymorphisms (SNPs) (354Tyr↔Phe and 1078Phe↔Tyr) in the LdMT gene of the parasites.ConclusionsHere, we document two laboratory confirmed cases of miltefosine resistant VL from India. Our finding highlights the urgent need to establish control measures to prevent the spread of these strains. We also propose that LdMT gene mutation analysis could be used as a molecular marker of miltefosine resistance in L. donovani.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-017-1969-z) contains supplementary material, which is available to authorized users.
Highlights d miR551b-3p translocates to the nucleus and activates STAT3 transcription d Importin-8 (IPO8) is required for the nuclear translocation of miR551b-3p d miR551b-3p activates the expression of OSM family genes for autocrine signaling loop d Inhibition of miR551b-3p disrupts OSM-mediated signaling addiction
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