l-Arginine Uptake by Cationic Amino Acid Transporter Promotes Intra-Macrophage Survival of Leishmania donovani by Enhancing Arginase-Mediated Polyamine Synthesis
Authors: Ruby Singh
Ajay Kumar
Pradeep Das
Abhishek Mandal
Sudha Verma
Ayan Kumar Ghosh
Saptarshi Roy
Abul Hasan Sardar
Sushmita Das
Kumar Abhishek
Bidyut Purkait
Savita Saini
Chitra Mandal
Ashish Kumar
Journal: Frontiers in Immunology (2017)
Discipline: IMMUNOLOGY
Keywords: CAT-2; Leishmania; arginase; cytokine; l-arginine
Affiliations: Department of Molecular Biology, Rajendra Memorial Research Institute of Medical Sciences (ICMR), Patna, India., Department of Microbiology, All India Institute of Medical Sciences (AIIMS), Patna, India., Cancer Biology and Inflammatory Disorder Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India., Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Hajipur, India.

Abstract:  The survival of intracellular protozoan parasite, Leishmania donovani, the causative agent of Indian visceral leishmaniasis (VL), depends on the activation status of macrophages. l-Arginine, a semi-essential amino acid plays a crucial regulatory role for activation of macrophages. However, the role of l-arginine transport in VL still remains elusive. In this study, we demonstrated that intra-macrophage survival of L. donovani depends on the availability of extracellular l-arginine. Infection of THP-1-derived macrophage/human monocyte-derived macrophage (hMDM) with Leishmania, resulted in upregulation of l-arginine transport. While investigating the involvement of the transporters, we observed that Leishmania survival was greatly impaired when the transporters were blocked either using inhibitor or siRNA-mediated downregulation. CAT-2 was found to be the main isoform associated with l-arginine transport in L. donovani-infected macrophages. l-arginine availability and its transport regulated the host arginase in Leishmania infection. Arginase and inducible nitric oxide synthase (iNOS) expression were reciprocally regulated when assayed using specific inhibitors and siRNA-mediated downregulation. Interestingly, induction of iNOS expression and nitric oxide production were observed in case of inhibition of arginase in infected macrophages. Furthermore, inhibition of l-arginine transport as well as arginase resulted in decreased polyamine production, limiting parasite survival inside macrophages. l-arginine availability and transport regulated Th1/Th2 cytokine levels in case of Leishmania infection. Upregulation of l-arginine transport, induction of host arginase, and enhanced polyamine production were correlated with increased level of IL-10 and decreased level of IL-12 and TNF-α in L. donovani-infected macrophages. Our findings provide clear evidence for targeting the metabolism of l-arginine and l-arginine-metabolizing enzymes as an important therapeutic and prophylactic strategy to treat VL. 

Retracted: No

PubPeer comments:
 Concern about Figure 2: the CAT-2 panel from the THP-1 cells looks very similar to the CAT-2 panel from the hMDM cells. Shown with pink boxes. ![file] , 
 Concern about Figure 7C and 10: the Arg-1 panels look very similar to each other. Shown with aqua boxes. ![file] , 
 Concern about Figure 11. Two GAPDH panels look very similar. Note a little round dot at the top left part of the right band, marked in green boxes. ![file] , 
 Correction, January 2020: https: www.frontiersin.org articles 10.3389 fimmu.2019.03101 full  In the original article, there were mistakes in Figure 2D, Figure 2E, Figure 7C, Figure 10 (blot image), Figure 11A and Figure 11C as published. The same image was unintentionally provided for (1) CAT-2 panel in Figure 2D and Figure 2E (2) Arg-1 panel in Figure 7C and Figure 10 (blot image) (3) GAPDH panel in Figure 11A and Figure 11C. The corrected Figures 2, 7, 10, and 11 appear below. Can the authors please comment on the high number mistakes that were detected and addressed with this correction? Are they confident that there are no other mistakes remaining? ,