Browsing by Author "Naveen K. Singh"

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CD300a Receptor Blocking Enhances Early Clearance of Leishmania donovani From Its Mammalian Host Through Modulation of Effector Functions of Phagocytic and Antigen Experienced T Cells
(Frontiers Media S.A., 2022) Rajan Singh; Anshul Anand; Arun K. Rawat; Shashi Saini; Baishakhi Mahapatra; Naveen K. Singh; Alok K. Mishra; Samer Singh; Nisha Singh; Dhiraj Kishore; Vinod Kumar; Pradeep Das; Rakesh K. Singh
The parasites of the genus Leishmania survive and proliferate in the host phagocytic cells by taking control over their microbicidal functions. The parasite also promotes differentiation of antigen-specific anti-inflammatory cytokines producing effector T cells, which eventually results in disease pathogenesis. The mechanisms that parasites employ to dominate host adaptive immunity are largely unknown. For the first time, we report that L. donovani, which causes visceral leishmaniasis in the Indian subcontinent, upregulates the expression of an immune inhibitory receptor i.e., CD300a on antigen presenting and phagocytic cells to dampen their effector functions. The blocking of CD300a signals in leishmania antigens activated macrophages and dendritic cells enhanced the production of nitric oxide, pro-inflammatory cytokines along with MHCI/II genes expression, and reduced parasitic uptake. Further, the abrogation of CD300a signals in Leishmania infected mice benefited antigen-experienced, i.e., CD4+CD44+ and CD8+CD44+ T cells to acquire more pro-inflammatory cytokines producing phenotypes and helped in the early clearance of parasites from their visceral organs. The CD300a receptor blocking also enhanced the conversion of CD4+ T effectors cells to their memory phenotypes i.e., CCR7high CD62Lhigh up to 1.6 and 1.9 fold after 14 and 21 days post-infection, respectively. These findings implicate that CD300a is an important determinant of host phagocytic cells functions and T cells differentiation against Leishmania antigens. Copyright © 2022 Singh, Anand, Rawat, Saini, Mahapatra, Singh, Mishra, Singh, Singh, Kishore, Kumar, Das and Singh.
Potential of Plants and Microbes for the Removal of Metals: Eco-Friendly Approach for Remediation of Soil and Water
(Elsevier Inc., 2015) Naveen K. Singh; Rajeev P. Singh
The potential of plants and their associated microorganisms to serve as an environmental counterbalance to industrial pollution has recently been recognized. Although the use of marginal land contaminated with heavy metals for biofuel production can reduce the need to use viable crop land, it is also important to remove contaminants from these sites as biofuel plants are not concerned with food chain contamination. In plants, a rhizosphere zone is a range of processes that induce either directly by the activity of plant roots or by the activity of rhizosphere microflora. Plant rhizospheric secretion of various organic acids, aided by plant-producing chelating agents, pH changes, and redox reactions, are able to solubilize and accumulate at low levels, even from nearly insoluble precipitates. The roots also provide a resourceful habitat for the growth of different types of bacteria (gram negative) and fungi that facilitate growth, nutrition, plant competitiveness, and reducing trace elements toxicity or increasing labile metal pools and uptake by roots. The use of aquatic or terrestrial plants to remove heavy metals from contaminated sites has been extensively tested and studied. There are also many reports on the metal-resistant root-associated beneficial microbes that could improve plant survival in metal-polluted soils and enhance heavy metal extraction by plants. © 2016 Elsevier Inc. All rights reserved.