Evaluation of Leishmania donovani disulfide isomerase as a potential target of cellular immunity against visceral leishmaniasis

• Published in: Cellular immunology 2014-05, Vol.289 (1-2), p.76-85
• Main Authors: Amit, Ajay, Chaudhary, Rajesh, Yadav, Anupam, Suman, Shashi S., Narayan, Shyam, Das, V.N.R., Pandey, K., Singh, S.K., Singh, Bipin K., Ali, Vahab, Das, Pradeep, Bimal, Sanjiva
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Alanine - pharmacology; Female; Humans; Immunity, Cellular - immunology; Immunologic Factors - immunology; Immunosuppression; Inducible nitric oxide; Interferon-gamma; Interferon-gamma - biosynthesis; Interleukin-10; Interleukin-10 - biosynthesis; L-Lactate Dehydrogenase; Lactate dehydrogenase; Leishmania donovani; Leishmania donovani - enzymology; Leishmaniasis, Visceral - immunology; Macrophages - immunology; Macrophages - parasitology; Male; Nitric Oxide - secretion; Protein disulfide isomerase; Protein Disulfide-Isomerases - immunology; Visceral leishmaniasis; Young Adult
• ISSN: 0008-8749; 1090-2163
• DOI: 10.1016/j.cellimm.2014.03.011

15kDa protein of PDI is directly linked to pathogenicity but its activity is inhibited by alanine in Indian cases of visceral leishmaniasis. [Display omitted] •We purified recombinant PDI from Leishmania donovani which was of 15kDa molecular size.•r-Ld PDI proved to be virulent factor for LD in VL patients.•rLd-PDI caused strong immunosuppression in VL patients.•Alanine reduced activities of PDI of Ld and induced collateral protective immunity in VL. In Leishmania species, protein disulfide isomerase (PDI) – a redox chaperone is primarily associated with virulence and survival. The precise mechanism, especially in relation to redox changes and its effects on immunological responses in visceral leishmaniasis (VL) is not completely understood as yet. Therefore, we purified a recombinant PDI from Leishmania donovani (r-LdPDI) which was of ∼15kDa molecular size and examined its effects on immunological responses in peripheral blood (PBMC) of human VL cases. For these studies, alanine was tested as an inhibitor and was used in parallel to all experiments. This protein was identified to have a direct correlation with parasite growth which significantly increased number of promastigotes as well as axenic amastigotes after 96h of culture. Our experiments examining the immunological response against r-LdPDI also indicate the activation of pro-L. donovani dictated immunological responses in VL. The stimulation of PBMC with r-LdPDI induced lactate dehydrogenase (LDH) activities and up regulated interleukin-10 (IL-10) production but not the HLA-DR expression, Nitric oxide (NO) release and IFN-γ production indicating a pivoted role for r-LdPDI in causing a strong immunosuppression in a susceptible host. Further, we observed that an addition of alanine in L. donovani culture offers a significant inhibition in growth of parasite and helps in reconstitution of protective immune response in VL cases. Therefore, we demonstrate a future cross talk on use of alanine which can reduce the activities of PDI of L. donovani, eliminating the parasite induced immunosuppression and inducing collateral host protective response in VL.