Bioactivity guided fractionation of Moringa oleifera Lam. flower targeting Leishmania donovani.

Leishmaniases is a group of diseases caused by the protozoan parasite belonging to the genus Leishmania. At least 20 species of Leishmania are known to infect humans transmitted by female sandflies, Phlebotomus spp. Leishmania donovani causes visceral leishmaniasis, considered most lethal among the common three forms of leishmaniasis.

Antiproteolytic and leishmanicidal activity of Coccinia grandis (L.) Voigt leaf extract against Leishmania donovani promastigotes.

In visceral leishmaniasis (VL), development of alternative safe therapeutic strategy is gaining paramount wherein natural components of plant origin have prominence. We explored Coccinia grandis (L.) Voigt, a medicinal plant known in traditional folk medicine, for its antileishmanial efficacy.

Identification and characterization of a Leishmania donovani serine protease inhibitor: Possible role in regulation of host serine proteases.

Aims: This study aims to identify, purify, and characterize an endogenous serine protease inhibitor from an Indian strain of Leishmania donovani, which causes the fatal visceral leishmaniasis.

Main Methods: (i) Reverse zymography was used to identify the serine protease inhibitor by inhibiting the gelatinolytic activity of serine protease. (ii) Purification was performed by combining heat treatment, ultracentrifugation, and affinity and gel permeation chromatography.

Effect of different serine protease inhibitors in validating the 115 kDa Leishmania donovani secretory serine protease as chemotherapeutic target.

Proteases have been considered as an important group of targets for development of antiprotozoal drugs due to their essential roles in host-parasite interactions, parasite immune evasion, life cycle transition and pathogenesis of parasitic diseases. The development of potent and selective serine protease inhibitors targeting L. donovani secretory serine protease (pSP) could pave the way to the discovery of potential antileishmanial drugs.

Leishmania donovani secretory serine protease alters macrophage inflammatory response via COX-2 mediated PGE-2 production.

Leishmania parasites determine the outcome of the infection by inducing inflammatory response that suppresses macrophage's activation. Defense against Leishmania is dependent on Th1 inflammatory response by turning off macrophages' microbicidal property by upregulation of COX-2, as well as immunosuppressive PGE-2 production. To understand the role of L.

TLR4-mediated activation of MyD88 signaling induces protective immune response and IL-10 down-regulation in Leishmania donovani infection.

In visceral leishmaniasis, a fragmentary IL-12 driven type 1 immune response along with the expansion of IL-10 producing T-cells correlates with parasite burden and pathogenesis. Successful immunotherapy involves both suppression of IL-10 production and enhancement of IL-12 and nitric oxide (NO) production. As custodians of the innate immunity, the toll-like receptors (TLRs) constitute the first line of defense against invading pathogens.

TLR mediated GSK3β activation suppresses CREB mediated IL-10 production to induce a protective immune response against murine visceral leishmaniasis.

During Leishmania donovani (LD) infection Interleukin (IL)-10 favors parasite replication and plays a central role as a target for immune-based therapy. Glycogen synthase kinase 3 (GSK3)β differentially regulates TLR-mediated cytokine production. CREB, an important transcription factor that induces IL-10 production is negatively regulated by GSK3β.

In vitro anti-leishmanial efficacy of potato tuber extract (PTEx): leishmanial serine protease(s) as putative target.

Leishmaniasis, a neglected tropical disease (NTD) causes major health problems in the tropical and subtropical world. Most of the antileishmanial modern therapies with different formulations of pentavalent antimonials, Miltefosine, Amphotericin B etc. are not satisfactory in recent times due to high toxicity to the host and present rising strain resistance issues.

Protease inhibitors in potential drug development for Leishmaniasis.

Leishmaniasis is a deadly protozoan parasitic disease affecting millions of people worldwide. The treatment strategy of Leishmania infection depends exclusively on chemotherapy till date. But the treatment of the disease is greatly hampered due to high cost, toxicity of the available drugs and more importantly emergence of drug resistance.

In vivo and in vitro antileishmanial activity of Bungarus caeruleus snake venom through alteration of immunomodulatory activity.

Leishmaniasis threatens more than 350 million people worldwide specially in tropical and subtropical region. Antileishmanial drugs that are currently available have various limitations. The search of new drugs from natural products (plants, animals) possessing antileishmanial activity is ventured throughout the world.

TLR-mediated distinct IFN-γ/IL-10 pattern induces protective immunity against murine visceral leishmaniasis.

Resistance to murine visceral leishmaniasis (VL) correlates with the development of an IFN-γ predominant immune response. Beta1,4-galactose terminal glycans are potent inducers of IFN-γ. Here, we demonstrate the efficacy of a 29 kDa β1,4-galactose terminal glycoprotein (GP29) of Leishmania donovani (LD) in an in vitro macrophage model and an in vivo mouse model of VL.

TLR4 and NKT cell synergy in immunotherapy against visceral leishmaniasis.

NKT cells play an important role in autoimmune diseases, tumor surveillance, and infectious diseases, providing in most cases protection against infection. NKT cells are reactive to CD1d presented glycolipid antigens. They can modulate immune responses by promoting the secretion of type 1, type 2, or immune regulatory cytokines.

115 kDa serine protease confers sustained protection to visceral leishmaniasis caused by Leishmania donovani via IFN-γ induced down-regulation of TNF-α mediated MMP-9 activity.

Visceral leishmaniasis caused by the intracellular parasite Leishmania donovani is a major public health problem in the developing world. The emergence of increasing number of L. donovani strains resistance to antimonial drugs recommended worldwide requires the intervention of effective vaccine strategy for treatment of VL.

Asiaticoside induces tumour-necrosis-factor-α-mediated nitric oxide production to cure experimental visceral leishmaniasis caused by antimony-susceptible and -resistant Leishmania donovani strains.

Objectives: The aim of this study was to investigate and characterize the efficacy of asiaticoside in an experimental model of visceral leishmaniasis caused by antimony-susceptible (AG83) and -resistant (GE1F8R and K39) Leishmania donovani.

Methods: The effect of asiaticoside was evaluated by microscopic counting of intracellular amastigotes in cultured macrophages stained with Giemsa. The antileishmanial effect of the compounds was assessed in infected BALB/c mice by estimation of splenic and liver parasite burdens in Leishman Donovan units.

Mechanism of amphotericin B resistance in clinical isolates of Leishmania donovani.

The clinical value of amphotericin B, the mainstay therapy for visceral leishmaniasis in sodium antimony gluconate-nonresponsive zones of Bihar, India, is now threatened by the emergence of acquired drug resistance, and a comprehensive understanding of the underlying mechanisms is the need of the hour. We have selected an amphotericin B-resistant clinical isolate which demonstrated 8-fold-higher 50% lethal doses (LD(50)) than an amphotericin B-sensitive strain to explore the mechanism of amphotericin B resistance. Fluorimetric analysis demonstrated lower anisotropy in the motion of the diphenylhexatriene fluorescent probe in the resistant strain, which indicated a higher fluidity of the membrane for the resistant strain than for the sensitive strain.

Leishmania donovani glycosphingolipid facilitates antigen presentation by inducing relocation of CD1d into lipid rafts in infected macrophages.

NKT cells respond to presentation of specific glycolipids with release of both Th1- and Th2-type cytokines. Leishmania donovani (LD)-infected splenic macrophages (sMϕ(I)) and bone marrow-derived dendritic cells (BMDC(I)) failed to activate NKT cells in response to α-galactosyl ceramide (α-GalCer). The defective antigen presentation could be corrected by treating the cells with the immunostimulating glycosphingophospholipid (GSPL) of LD parasites.

Immunolocalization and characterization of two novel proteases in Leishmania donovani: putative roles in host invasion and parasite development.

Two novel intracellular proteases having identical molecular mass (58 kDa) were purified from virulent Indian strain of Leishmania donovani by a combination of aprotinin-agarose affinity chromatography, ion exchange chromatography and finally continuous elution electrophoresis. Both of these proteases migrate in SDS-PAGE as a single homogeneous bands suggesting monomeric nature of these proteases. The enzyme activity of one of the proteases was inhibited by serine protease inhibitor aprotinin and another one was inhibited by metalloprotease inhibitor 1, 10 phenanthroline.

In situ immunolocalization and stage-dependent expression of a secretory serine protease in Leishmania donovani and its role as a vaccine candidate.

Proteases have been found to play essential roles in many biological processes, including the pathogenesis of leishmaniasis. Most parasites rely on their intracellular and extracellular protease repertoire to invade and multiply in mammalian host cells. However, few studies have addressed serine proteases in Leishmania and their role in host pathogenesis.

Complete protection against experimental visceral leishmaniasis with complete soluble antigen from attenuated Leishmania donovani promastigotes involves Th1-immunity and down-regulation of IL-10.

Compared with cutaneous leishmaniasis, vaccination against visceral leishmaniasis has received limited attention. Most available drugs are toxic, and relapse after cure remains a chronic problem. Growing limitations in available chemotherapeutic strategies due to emerging resistant strains and lack of an effective vaccine strategy against visceral leishmaniasis deepens the crisis.

UDP-Gal: N-acetylglucosamine beta 1-4 galactosyltransferase expressing live attenuated parasites as vaccine for visceral leishmaniasis.

As compared to cutaneous leishmaniasis, vaccination against visceral leishmaniasis (VL) has received limited attention. In this study, we demonstrate for the first time that an UDP-Galactose: N-acetylglucosamine beta 1-4 galactosyltransferase (GenBank Accession No. EF159943) expressing attenuated LD clonal population (A-LD) is able to confer protection against the experimental challenge with the virulent LD AG83 parasite.

Identification, purification, and characterization of a secretory serine protease in an Indian strain of Leishmania donovani.

An aprotinin sensitive serine protease was identified in the culture supernatant of the Indian strain of Leishmania donovani (MHOM/IN/1983/AG83). The protease was subsequently purified and characterized. The apparent molecular mass of the enzyme was 115 kDa in SDS-PAGE under non-reducing condition, while on reduction it showed a 56 kDa protein band indicating that the protease is a dimeric protein.

Immuno stimulating glycophosphosphingolipid antigen from Leishmania donovani is recognized by visceral leishmaniasis patient sera.

Surface antigens on Leishmania promastigotes and infected macrophages are obvious targets in immunoprophylaxis for leishmanial infection. The glycophosphosphingolipid (GSPL) antigen isolated from Leishmania donovani surface membrane was recognized by sera from patients with visceral leishmaniasis. GSPL was also expressed on the membrane of parasite-infected macrophages.

Hybrid cell vaccination resolves Leishmania donovani infection by eliciting a strong CD8+ cytotoxic T-lymphocyte response with concomitant suppression of interleukin-10 (IL-10) but not IL-4 or IL-13.

There is an acute dearth of therapeutic interventions against visceral leishmaniasis that is required to restore an established defective cell-mediated immune response. Hence, formulation of effective immunotherapy requires the use of dominant antigen(s) targeted to elicit a specific antiparasitic cellular immune response. We implemented hybrid cell vaccination therapy in Leishmania donovani-infected BALB/c mice by electrofusing dominant Leishmania antigen kinetoplastid membrane protein 11 (KMP-11)-transfected bone marrow-derived macrophages from BALB/c mice with allogeneic bone marrow-derived dendritic cells from C57BL/6 mice.

Kinetoplastid membrane protein-11 DNA vaccination induces complete protection against both pentavalent antimonial-sensitive and -resistant strains of Leishmania donovani that correlates with inducible nitric oxide synthase activity and IL-4 generation: evidence for mixed Th1- and Th2-like responses in visceral leishmaniasis.

The emergence of an increasing number of Leishmania donovani strains resistant to pentavalent antimonials (SbV), the first line of treatment for visceral leishmaniasis worldwide, accounts for decreasing efficacy of chemotherapeutic interventions. A kinetoplastid membrane protein-11 (KMP-11)-encoding construct protected extremely susceptible golden hamsters from both pentavalent antimony responsive (AG83) and antimony resistant (GE1F8R) virulent L. donovani challenge.