Visceral leishmaniasis

About: Visceral leishmaniasis is a research topic. Over the lifetime, 7486 publications have been published within this topic receiving 184865 citations. The topic is also known as: Kala-Azar & viscus leishmaniasis.

IL-10-producing Th1 cells and disease progression are regulated by distinct CD11c⁺ cell populations during visceral leishmaniasis.

Abstract: IL-10 is a critical regulatory cytokine involved in the pathogenesis of visceral leishmaniasis caused by Leishmania donovani and clinical and experimental data indicate that disease progression is associated with expanded numbers of CD4+ IFNγ+ T cells committed to IL-10 production. Here, combining conditional cell-specific depletion with adoptive transfer, we demonstrate that only conventional CD11chi DCs that produce both IL-10 and IL-27 are capable of inducing IL-10-producing Th1 cells in vivo. In contrast, CD11chi as well as CD11cint/lo cells isolated from infected mice were capable of reversing the host protective effect of diphtheria toxin-mediated CD11c+ cell depletion. This was reflected by increased splenomegaly, inhibition of NO production and increased parasite burden. Thus during chronic infection, multiple CD11c+ cell populations can actively suppress host resistance and enhance immunopathology, through mechanisms that do not necessarily involve IL-10-producing Th1 cells.

Cytokine Responses to Novel Antigens in an Indian Population Living in an Area Endemic for Visceral Leishmaniasis

Abstract: Background: There are no effective vaccines for visceral leishmaniasis (VL), a neglected parasitic disease second only to malaria in global mortality. We previously identified 14 protective candidates in a screen of 100 Leishmania antigens as DNA vaccines in mice. Here we employ whole blood assays to evaluate human cytokine responses to 11 of these antigens, in comparison to known defined and crude antigen preparations. Methods: Whole blood assays were employed to measure IFN-c, TNF-a and IL-10 responses to peptide pools of the novel antigens R71, Q51, L37, N52, L302.06, J89, M18, J41, M22, M63, M57, as well as to recombinant proteins of tryparedoxin peroxidase (TRYP), Leishmania homolog of the receptor for activated C kinase (LACK) and to crude soluble Leishmania antigen (SLA), in Indian patients with active (n=8) or cured (n=16) VL, and in modified Quantiferon positive (EHC +ve , n=20) or modified Quantiferon negative (EHC 2ve , n=9) endemic healthy controls (EHC). Results: Active VL, cured VL and EHC +ve groups showed elevated SLA-specific IFN-c, but only active VL patients produced IL10 and EHC +ve did not make TNF-a. IFN-c to IL-10 and TNF-a to IL-10 ratios in response to TRYP and LACK antigens were higher in cured VL and EHC +ve exposed individuals compared to active VL. Five of the eleven novel candidates (R71, L37, N52, J41, and M22) elicited IFN-c and TNF-a, but not IL-10, responses in cured VL (55–87.5% responders) and EHC +ve (40– 65% responders) subjects. Conclusions: Our results are consistent with an important balance between pro-inflammatory IFNc and TNFc cytokine responses and anti-inflammatory IL-10 in determining outcome of VL in India, as highlighted by response to both crude and defined protein antigens. Importantly, cured VL patients and endemic Quantiferon positive individuals recognise 5 novel vaccine candidate antigens, confirming our recent data for L. chagasi in Brazil, and their potential as cross-species vaccine candidates.

Dendritic cell-based immunotherapy combined with antimony-based chemotherapy cures established murine visceral leishmaniasis.

Abstract: Dendritic cells (DCs) have been proposed to play a critical role as adjuvants in vaccination and immunotherapy. In this study we evaluated the combined effect of soluble Leishmania donovani Ag (SLDA)-pulsed syngeneic bone marrow-derived DC-based immunotherapy and antimony-based chemotherapy for the treatment of established murine visceral leishmaniasis. Three weekly injections of SLDA-pulsed DCs into L. donovani-infected mice reduced liver and splenic parasite burden significantly, but could not clear parasite load from these organs completely. Strikingly, the conventional antileishmanial chemotherapy (sodium antimony gluconate) along with injections of SLDA-pulsed DCs resulted in complete clearance of parasites from both these organs. Repetitive in vitro stimulation of splenocytes from uninfected or L. donovani-infected mice with SLDA-pulsed DCs led to the emergence of CD4(+) T cells with characteristics of Th1 cells. Our data indicate that DC-based immunotherapy enhances the in vivo antileishmanial potential of antimony or vice versa.

Immunoenhancement Combined with Amphotericin B as Treatment for Experimental Visceral Leishmaniasis

Abstract: To determine if stimulation of Th1-cell-associated immune responses, mediated by interleukin 12 (IL-12) and gamma interferon (IFN-γ), enhance the antileishmanial effect of amphotericin B (AMB), Leishmania donovani-infected BALB/c mice were first treated with (i) exogenous IL-12 to induce IFN-γ, (ii) agonist anti-CD40 monoclonal antibody (MAb) to maintain IL-12 and induce IFN-γ, or (iii) anti-IL-10 receptor (IL-10R) MAb to blockade suppression of IL-12 and IFN-γ. In animals with established visceral infection, low-dose AMB alone (two injections of 1 mg/kg of body weight; total dose, 2 mg/kg) killed 15 to 29% of liver parasites; by themselves, the immunointerventions induced 16 to 33% killing. When the interventions were combined, the leishmanicidal activities increased 3.4-fold (anti-CD40), 6.3-fold (anti-IL-10R), and 9-fold (IL-12) compared with the activities of AMB plus the control preparations; and overall killing (76 to 84%) approximated the 84 to 92% killing effect of 7.5-fold more AMB alone (three injections of 5 mg/kg; total dose, 15 mg/kg). These results suggest that strengthening the host Th1-cell response may be a strategy for the development of AMB-sparing regimens in visceral leishmaniasis.

Miltefosine as an effective choice in the treatment of post‐kala‐azar dermal leishmaniasis

Abstract: Summary Background Post-kala-azar dermal leishmaniasis (PKDL) constitutes a parasite reservoir important in the transmission of visceral leishmaniasis (VL). Unacceptable treatment regimens and increasing drug resistance blight control programmes. The success of oral miltefosine in VL prompted a clinical, histopathological and parasitological study of this drug in PKDL. Objectives To define the dose and duration of miltefosine for treatment of PKDL. Methods Twenty-six patients confirmed by slit-skin smear, histopathology and molecular tests were enrolled in the study. They received miltefosine capsules 50 mg thrice daily after food. Treatment was for 60 days with a provision to increase by 30 days if a responder had not attained a cure. Cure was ascertained by clinical and histopathological examination, and measuring parasite burden using real-time polymerase chain reaction. Results Twenty-four patients with a wide range of parasite burden completed the study. Twenty-three achieved a cure giving an initial cure rate of 96% (95% confidence interval 79–99%). Sixteen patients were cured with 50 mg thrice daily, 13 in 60 days and three within 90 days. In seven cases, miltefosine had to be reduced, because of gastrointestinal intolerance, to 50 mg twice daily to a total of 180 capsules. Lesional parasites were undetectable at 1 month post-treatment. Treatment was safe with no relapses at 1-year follow-up. Conclusion Oral miltefosine, 50 mg thrice daily for 60 days or twice daily for 90 days, could be an effective treatment for PKDL.