Evaluation of cellular immunological responses in mono- and polymorphic clinical forms of post-kala-azar dermal leishmaniasis in India

Abstract

SummaryPost-kala-azar dermal leishmaniasis (PKDL) is a chronic dermal complication that occurs usually after recovery from visceral leishmaniasis (VL). The disease manifests into macular, papular and/or nodular clinical types with mono-or polymorphic presentations. Here, we investigated differences in immunological response between these two distinct clinical forms in Indian PKDL patients. Peripheral blood mononuclear cells of PKDL and naive individuals were exposed in vitro to total soluble Leishmania antigen (TSLA). The proliferation index was evaluated using an enzyme-linked immunosorbent assay (ELISA)-based lymphoproliferative assay. Cytokines and granzyme B levels were determined by cytometric bead array. Parasite load in tissue biopsy samples of PKDL was quantified by quantitative polymerase chain reaction (qPCR). The proportion of different lymphoid subsets in peripheral blood and the activated T cell population were estimated using flow cytometry. The study demonstrated heightened cellular immune responses in the polymorphic PKDL group compared to the naive group. The polymorphic group showed significantly higher lymphoproliferation, increased cytokines and granzyme B levels upon TSLA stimulation, and a raised proportion of circulating natural killer (NK) T cells against naive controls. Furthermore, the polymorphic group showed a significantly elevated proportion of activated CD4 1 and CD8 1 T cells upon in-vitro TSLA stimulation. Thus, the polymorphic variants showed pronounced cellular immunity while the monomorphic form demonstrated a comparatively lower cellular response. Additionally, the elevated level of both activated CD4 1 and CD8 1 T cells, coupled with high granzyme B secretion upon in-vitro TSLA stimulation, indicated the role of cytotoxic cells in resistance to L. donovani infection in polymorphic PKDL.

Gene deleted live attenuated Leishmania vaccine candidates against visceral leishmaniasis elicit pro-inflammatory cytokines response in human PBMCs

“…We analyzed the capacity of Ld Cen1 −/− and Ld p27 −/− to stimulate TNF-α and found that similar to IL-12, significantly higher stimulation of TNF-α was seen only in the HVL and PKDL groups. The observed increase in production of Th1 cytokines (IFN-γ, TNF-α and IL-12) in Leishmania exposed group (HVL or PKDL) compared to naive or active VL individual in response to live attenuated or wild type Leishmania parasites, is in accordance with earlier studies carried out with Leishmania antigen in HVL and PKDL groups 33 34 40 44 . Further, this increase in Th1 cytokine production in pre-exposed group suggested that the live attenuated parasites can induce protective effector response from memory response generated during resolution of infection in HVL individuals.…”

“…In the present study, we observed significantly higher stimulation of IFN-γ in HVL and PKDL group as compared to the control uninfected cells and healthy group. Leishmanial antigens have previously been shown to induce stimulation of IFN-γ in PKDL and healed cases of VL, asymptomatic VL, cutaneous and mucocutaneous leishmaniasis 33 34 35 36 37 . In the present study significantly higher stimulation of IFN-γ was also found in the VL group as compared to the healthy group.…”

Ageing dangerously; homing of senescent CD8 T cells in cutaneous Leishmaniasis

“…The IFN‐γ‐driven Type 1 immune response to CL is both associated with a good prognosis, and also contributes significantly to immunopathology 1 . This protective‐but‐damaging immune response in CL is known to be dominated by CD4 + T cells and cytotoxic CD8 + T cells, which display cytotoxic functions 2,3 . It has also become apparent that other populations of cytotoxic cells, including Natural Killer (NK) cells may also contribute to pathogen clearance in CL 4 .…”

“…1 This protective-but-damaging immune response in CL is known to be dominated by CD4 + T cells and cytotoxic CD8 + T cells, which display cytotoxic functions. 2,3 It has also become apparent that other populations of cytotoxic cells, including Natural Killer (NK) cells may also contribute to pathogen clearance in CL. 4 In order to develop improved strategies for vaccination or develop strategies for therapeutic control post-infection, it is important to understand the contributions of immune cells to both pathogen clearance and to the infection-induced pathology.…”

Effects of Invariant NKT Cells on Parasite Infections and Hygiene Hypothesis

“…Post-kala-azar dermal leishmaniasis is a chronic dermal complication that occurs usually after recovery from visceral leishmaniasis. There was a raised proportion of circulating NKT cells in these patients compared to health controls [ 34 ]. Karmakar and colleagues isolated a natural ligand of NKT cells, β -(1–4)-galactose terminal glycosphingophospholipid (GSPL) from this parasite to treat infected BALB/c mice.…”