Caister Academic Press

Molecular Biology of Kinetoplastid Parasites | Book

Publisher: Caister Academic Press
Edited by: Hemanta K. Majumder
CSIR-Indian Institute of Chemical Biology, Kolkata, India
Pages: c. 250
Publication date: January 2018Buy book
ISBN: 978-1-910190-71-5
Price: GB £159 or US $319
Publication date: January 2018Buy ebook
ISBN: 978-1-910190-72-2
Price: GB £159 or US $319

Kinetoplastid parasites are responsible for a number of serious protozoal diseases with limited treatment options and few commercially available vaccines. Viewed globally, these parasites pose an increasing threat to human health and welfare.

Written by a team of authors active in the field of Leishmania and Trypanosoma research, this volume reviews the current research in kinetoplastid parasites. With an emphasis on cellular and molecular biology, areas covered include epigenetic regulation, cellular defence, manipulation of host macrophages, B lymphocyte response, adhesion and invasion of host tissues, immune evasion, immunotherapy, hemeproteins, phospholipids biosynthesis and DNA topoisomerases. A common theme throughout the book is the identification of new therapeutic targets for drug development.

This timely and up-to-date volume is essential reading for anyone working on kinetoplastid parasites and will also be of interest to parasitologists, immunologists and drug development researchers. All parasitology laboratories should have a copy of this important reference volume.

Table of contents
1. Genome-wide Profiling of Unique Domain Architectures Reveals Novel Epigenetic Regulators of Leishmania infantum
V. S. Gowri, Nimisha Mittal, Rohini Muthuswami and Rentala Madhubala
Leishmania, a protozoan parasite, constitutes a major source of human mortality and morbidity. Epigenetic gene regulation has emerged as a major mechanism for gene regulation. Not much is known about the post-translational histone modifications and chromatin-modifying enzymes in Leishmania. The resolution of the genome of Leishmania has enabled us to perform the first-ever genome-wide survey of the epigenetic regulator proteins. In this chapter, the complete repertoire of epigenetic modulators comprising of 238 proteins [40 Writers, 16 Readers (excluding 32 Ankyrin repeat proteins and 121 WD40 proteins), 18 ATP-dependent chromatin remodelers belonging to SWI2/SNF2 family and 11 Erasers] is reported. Our analysis showed that the organism contained 30 lysine methyltransferases of which 18 were specific to kinetoplastids. 3 DOT1 methyltransferases were identified as against an earlier report of only 2 DOT1 homologs in T. brucei. Our analysis also showed that L. infantum, unlike human, contains only the second type of demethylases (Jumonji type) and LSD1 type demethylase is absent. Further, the organism contains 3 Class III (sirtuins) HDACs phylogenetically closer to the Gram-negative bacterial sirtuins. The present study provides new insights into a complete repertoire of histone-modifying enzymes that could help in better understanding of epigenetic regulation in Leishmania.
2. Role of Hypoxia Inducible Factor-1 in Leishmania-Macrophage Interaction: A New Therapeutic Paradigm
Amit Kumar Singh, Vivek G. Vishnu, Shalini Saini, Sandhya Sandhya and Chinmay K. Mukhopadhyay
Intracellular parasites use host components for their survival and growth after invasion within host, while hosts spread out their innate immune defences to deny any advantage to the invading parasite. The research in the last decade provided evidences of oxygen sensing mammalian transcription factor hypoxia-inducible factor-1 (HIF-1) as a master controller of innate immune response of phagocytes against various intracellular and extracellular pathogens. In response to most of these pathogens host phagocytes increase transcription of HIF-1α, the regulatory component of HIF-1, to express various effector molecules against invaders. The involvement of NFkB in regulating HIF-1α transcription further strengthened the paradigm. However, more recent evidences revealed that protozoan parasite Leishmania donovani (LD), the causative agent of fatal visceral leishmaniasis, in contrary could promote and exploit HIF-1 activation for its survival advantage within host macrophages. HIF-1 is a heterodimer of regulatory subunit HIF-1α and constitutive HIF-1β. In oxygen deficiency or cellular iron depletion, expression of HIF-1α is regulated by a post-translational protein stability mechanism mediated by a family of prolyl hydroxylases (PHDs), while during phagocytic invasion by pathogens HIF-1α is regulated mainly by a transcriptional mechanism. Interestingly, LD activates HIF-1 by both transcriptional and post translational protein stability mechanism. The current chapter will summarize the detail mechanism of HIF-1 activation and its potential role in survival advantage of intracellular LD within host macrophages. Due to its pivotal role in angiogenesis and cancer, HIF-1 is a crucial drug target and matter of intense research. The recent finding of role of host HIF-1 in survival and growth of LD thus presents an opportunity to repurpose the HIF-1 inhibitors as potential drugs against visceral leishmaniasis.
3. Response of B Lymphocyte During Leishmania Infection
Koushik Mondal and Syamal Roy
Leishmania protozoa affects peripheral B cell subset and expansion of multiple B cell clones leading to polyclonal B cell activation. Both cutaneous and visceral leishmaniasis stimulates polyclonal B cell activation leading to generation of self or autoantibody and secretion of IgG. The polyclonal B cell activation also stimulates and activates Transitional B cell and Marginal Zone B cell subsets to function as an IL-10 secreting regulatory B cell during infection. Protozoal parasite mediated generation of hypergammaglobulinemia and secretion of IL-10 are the major B cell immuno-pathological changes responsible for disease progression during leishmaniasis.
4. Cellular Defence of the Leishmania Parasite
Sanchita Das and Chandrima Shaha
One of the major defence approaches of host against a pathogen is to generate ROS (Reactive Oxygen Species) and RNS (Reactive Nitrogen Species) to eliminate infections. How the pathogen overcomes this stress response is the key to successful invasion and sustenance of infection.Leishmania spp. is accountable for the disease Leishmaniasis that manifests itself in a cutaneous or a visceral form and survives within macrophage phagosomes, the very compartments that are supposed to eliminate them. Leishmania spp. lacks catalases but has evolved several important defensive armories. These include, the peroxiredoxins, thiols, ascorbate peroxidase, selenoproteins, kinases and phosphatases. Available data on the variety of defence systems are discussed.
5. Molecular Regulation of Macrophage Class Switching in Indian Post-kala-azar Dermal Leishmaniasis (PKDL)
Mitali Chatterjee, Srija Moulik, Debkanya Dey, Debanjan Mukhopadhyay, Shibabrata Mukherjee and Susmita Roy
Leishmania donovani, the causative parasite responsible for Visceral Leishmaniasis (VL) and its chronic dermal sequel, post-kala-azar dermal leishmaniasis (PKDL) manipulates host monocytes/macrophages for ensuring its survival. Information regarding macrophage polarization is primarily derived from murine models, but growing evidence is emphasizing the inadequacy of direct inter-species translation. Accordingly, the status of monocytes/macrophages with regard to plasticity and polarization in circulation and dermal lesions of patients with PKDL was characterized. The raised plasma levels of IL-4/IL-13 and IL-10 in patients with PKDL confirmed the presence of a microenvironment conducive for alternative activation of monocytes/macrophages. Furthermore, the mRNA expression of il-10, ifn-γ, mrc-1, arg-1,, vitamin D signalling pathway (vdr, cyp27b1, ll-37), was examined in circulation and lesional sites, wherein there was a consistent increase in expression of M2 markers. Conversely, the classical macrophage activation markers showed a consistent decline in generation of reactive oxygen and nitrogen intermediates, expression of Toll like receptors 2 and 4 (CD282/284) along with impairment of the MAP kinase pathway. Taken together, impairment of antigen presentation along with an increased presence of alternatively activated monocyte/macrophage subsets sustained parasite survival and facilitated disease persistence. Accordingly, immunomodulators capable of evoking a reduction in M2 monocytes/macrophage population or enhancing their switching from M2 to M1 could be an effective chemotherapeutic strategy against Leishmaniasis.
6. Leishmania Exploits Host's Defence Machineries for Survival: A Tale of Immune Evasion
Amrita Saha and Anindita Ukil
The disease Leishmaniasis caused by protozoan parasite of genus Leishmania, is a major health concern as over 12 million people are affected worldwide. The disease comprises of spectrum of clinical manifestations ranging from self-healing cutaneous lesions to life threatening infection of visceral organs to death. The lifestyle of Leishmania is that of an obligate intracellular parasite that resides and multiplies within the phagolysosome of host macrophages. Interestingly, these macrophages are the sentinels of the immune system,that are specialized for the destruction of invading pathogens. Therefore, in order to successfully dwell within its niche, Leishmania has had to evolve range of sophisticated mechanisms to subvert normal macrophage functioning. There are multiple ways by which intracellular pathogens like Leishmania make use of host cell's machinery in order to survive and replicate, either by employing strategies to inhibit proteins that play a positive role in immune cell activation or by activating molecules that act as negative regulators of immune cell signalling and function. Current research has focused on parasite induced alteration of host cell signalling pathways, combating microbicidal free radical generation and modulation of cytokine/chemokine profiles that alter immune cell activation and antigen presentation. The aim of this chapter is to highlight the molecular mechanisms underlying immune evasion strategies whereby Leishmania can subvert host surveillance, thereby exploiting the macrophage environment in its favour for its persistence. Understanding these mechanisms in detail may open up new perspectives on potential molecular pathways that are prone to pharmacological manipulation and can prove as promising areas for preclinical and clinical research.
7. Ceramide in the Establishment of Visceral Leishmaniasis, an Insight into Membrane Architecture and Pathogenicity
Junaid J. Jawed, Shabina Parveen and Subrata Majumdar
Biological membrane are the permeability barrier for the selective entry of biomolecules but sometime it is responsible for providing platform for the entry and establishment of infection. Sphingomyelins are the chief component of the most of the biological membranes, ceramide being one of its important component. Generation of ceramide leads to increased susceptibility of the host towards parasite. Increased endogenous ceramide resulted into elevated expression of PKC ζ which causes downregulation of essential component of MAPK pathways including p-38, JNK and on the other hand increases the phosphorylation of ERK1/2. Alternative activation of different MAPKs ultimately leads to reduced nuclear translocation of NFkB and AP-1 as a result of which the cell show increased synthesis of immunosuppressive cytokines like TGF-β and IL-10 along with reduced NO generation, leading to severe host immune suppression. On the other hand ceramide also induced by de novo pathway which further shows increased membrane fluidity and hampered antigen presentation and reciprocal regulation of different T cell subsets including T-reg and Th-17 cells. Collectively the roles of ceramide in infectious diseasesis of great importance and can be a specific target for designing therapy against infection.
8. The Role of Hemeproteins in Different Life Cycle Stages of Leishmania
Subhankar Dolai and Subrata Adak
Hemeproteins are iron protoporphyrin IX prosthetic group/co-factor containing proteins that are widely distributed among prokaryotes and eukaryotes to carry out vital cellular functions, which are necessary for survival. To perpetuate infection and survive for successful disease establishment, Leishmania pathogens adopt different morphology through differentiation, manipulate cellular metabolism, programme cell signalling to thrive within hypoxic arthropod vector gut, employ antioxidant defence systems to evade reactive oxygen species that are generated as a result of cellular metabolism, and reactive nitrogen and oxygen species that are generated within activated vertebrate host macrophages. Genome sequencing reveals the presence of an array of hemeproteins in Leishmania with hypothetical functions. However, being phylogenetically distant, the Leishmania hemeproteins are distinct in primary structures and sometimes novel compared to their human host counterparts. In this chapter we have surmised the recent development in understanding of hemeprotein functions in Leishmania and their physiological roles in parasite life cycle to better understand the pathogenesis, and the novel parasite survival strategies that could be exploited as possible therapeutic targets.
9. Pre-adaptation of Leishmania Promastigotes to Intracellular Life: Ensuring a Successful Infection
Roma Sinha and Nahid Ali
Leishmaniasis is a group of diseases with diverse phenotype from self-healing cutaneous lesions to fatal visceral infections. The complex life-cycle of the parasite Leishmania in its vector and host as well as the vector and host characteristics determine the severity of infection. Leishmania has evolved several strategies to survive as extracellular promastigotes in the sandfly vector and successfully transform to amastigotes sensing an increase in temperature and acidic pH inside the macrophages. In this review we have discussed the physiological and biochemical changes in promastigotes which make them infective and how these infection ready parasites respond to intramacrophagic stress. We have summed up the changes in expression of structural proteins, virulence factors (including species-specific virulence factors), and stress related proteins when the parasites convert to metacyclic promastigotes and then from metacyclics to amastigotes, and how these pathways have been targeted for therapy. The trends in global gene expression of Leishmania under various conditions and at various life-stages using modern molecular biology approaches like genomics, transciptomics, proteomics and metabolomics have been discussed in conjunction with the theory of pre-adaptation of the parasites for life inside macrophages.
10. DNA Topoisomerases of Kinetoplastid Parasites: Brief Overview and Recent Perspectives
Sourav Saha, Somenath R. Chowdhury and Hemanta K. Majumder
Topoisomerases are group of enzymes that resolve DNA topological problems and aids different DNA transaction processes viz. replication, transcription, recombination etc. inside cells. These proteins accomplish their feats by steps of DNA strand(s) scission, strand passage or rotation and subsequent rejoining activities. Topoisomerases of kinetoplastid parasites have been extensively studied because of their unusual features. The unique presence of heterodimeric Type IB topoisomerase and prokaryotic 'TopA homologue' Type IA topoisomerase in kinetoplastids still generate immense interest among scientists. Moreover, because of their structural dissimilarity with the host enzymes, topoisomerases of kinetoplastid parasites are attractive targets for chemotherapeutic interventions to kill these deadly parasites. In this chapter, we summarize historical perspectives and recent advances in kinetoplastid topoisomerase research and how these proteins are exploited for drug targeting.
11. Host-Kinetoplastid Parasite Interaction at the Immune System Interface: Immune Evasion and Immunotherapy
Arathi Nair, Sunil Kumar, Bhaskar Saha and Divanshu Shukla
Parasites co-evolved with their respective hosts over millions of years. During the process of coevolution, host and parasite bequeath each other with a striking legacy of immune surveillance and immune evasion, respectively. The host-parasite interaction is thus dynamic and complete with cascades of temporally separated responses that characterize different phases of infection; the phases remain connected to each other as if one response leads to the next. In the first phase, the parasite's cell surface molecules interact with the pattern recognition receptors (PRR) on the host cell surface, followed by internalization and recognition of the parasite's intracellular molecules by the PRRs within the host cells. The results of these interactions include, but are not limited to, parasite survival or degradation, moderation of the antigen-presenting functions of the host cells and elicitation of the T cell responses that further control parasite survival in a host. The parasite in each phase modulates the host immune responses to engineer its own survival. Therefore, in this review, molecular interactions between the hosts and the parasites, Leishmania and Trypanosoma, will be described emphasizing the anti-parasite immune mechanisms and parasite-devised immune evasion. How this knowledge helps strategize anti-parasite therapy is also discussed.
12 . Extracellular Matrix Interacting Proteins of Trypanosomatids: Adhesion and Invasion of Host Tissues
Shreyasi Palit and Pijush K. Das
Extracellular matrix (ECM), a highly dynamic, complex three dimensional macromolecular structure is ubiquitously present in tissues forming the basal lamina. Comprising of laminin, collagen, fibronectin, elastin, proteoglycan and several other glycoproteins, ECM acts as a major mechanical barrier to almost all known invasive pathogens. Therefore, pathogens are constantly evolving measures to breach this barrier for their survival within the host. Most pathogens therefore remodel ECM either by binding to its component glycoproteins by their ECM binding proteins or by degrading the matrix by secreting several matrix-degrading enzymes in order to adhere, invade and survive within the host tissue. Recent advances have suggested trypanosomatids which include Leishmania sp., Trypanosoma sp., Phytomonas sp., etc., also utilize a repertoire of ECM interacting proteins in order to bind and mediate downstream signalling events in order to establish its niche. This article therefore emphasizes on understanding the array of proteins of trypanosomatids that interact with the ECM components of the host during the early stages of infection so that they can be exploited in future to develop new drugs.
13. Effects of Phospholipid Analogues on Trypanosomatids
Wanderley de Souza, Joseane Godinho, Emile Barrias, Marina Roussaki, Juliany C. F. Fernandes Rodrigues and Theodora Calogeropoulou.
Diseases caused by pathogenic protozoa that belong to the Trypanosomatidae these include Chagas' disease and sleeping sickness, which are caused by Trypanosoma cruzi and Trypanosoma brucei (rhodesiense and gambiense subspecies), respectively, and the various forms of leishmaniasis, caused by several species of the Leishmania genus. Although significant efforts have been directed at developing new chemotherapeutic strategies against trypanosomatids, the compounds routinely used in clinical practice are those that were identified many years ago (pentavalent antimonials, pentamidine, or liposomal amphotericin B for leishmaniasis; nifurtimox or benzinidazole for Chagas disese;). Several groups are working on the identification of new and more specific drug targets in trypanosomatids. One important recognized target is the phospholipids (PLs) biosynthesis in view of the important role played by these molecules in cell structure and functions. In this chapter we review basic aspects of the PLs biosynthetic pathways both in mammalian cells and in trypanosomatids. In addition special emphasis is given to the Phospholipid Analogues (PA) that constitute a new class of pharmaceutical compounds that exhibit excellent biocompatibility and an especial amphiphilicity making them appropriate to be employed as drugs with broad biological activity. The various possibilities to synthesize these compounds either by organic and/or enzymatic synthetic steps are discussed. Mention is made to the process of molecular hybridization which allows the synthesis of new hybrid molecules by combining two pharmacophores such as PAs with Trifluralin. Several PAs have been tested against parasitic protozoa and some of them have shown excellent anti parasite activity. One of them, miltefosine, has been introduced in clinics to treat leishmaniasis. We also review the effect of several PAs on the growth, morphology, cell cycle, lipid accumulation, and mitochondrion function in the parasites. These compounds are able to kill the parasites through mechanisms such as autophagy and/or a apoptotic-like cell death process.

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(EAN: 9781910190715 9781910190722 Subjects: [medical microbiology] [parasitology] )