sirolimus and Leishmaniasis--Visceral

Leishmaniases are a group of neglected tropical parasitic diseases, mainly affecting vulnerable populations of countries with poor socioeconomic status. Development of efficient vaccines is a priority due to the increasing incidence of drug resistance and toxicity to current treatments. In the search for a safe and efficient protective vaccine for human and dog visceral leishmaniases, we analyzed the suitability of the immunomodulatory drug sirolimus (SIR) to boost a preventive DNA vaccine against leishmaniasis. SIR is an already marketed drug that has been described to boost immune protection against different disease models and has also emerged as a promising therapeutic drug against L. major.. Syrian hamsters were treated with SIR concomitantly with the administration of a DNA vaccine formulation consisting in four plasmids carrying the Leishmania genes LACK, TRYP, PAPLE22 and KMPII, respectively. Two weeks after the last vaccination, the animals were infected intraperitoneally with L. infantum parasites. Five weeks post-infection the parasite load was measured by real-time PCR in target tissues and immune response was evaluated by determining anti-Leishmania specific antibodies in combination with cytokine expression in the spleen.. Our results show that the DNA vaccine itself efficiently reduced the burden of parasites in the skin (P = 0.0004) and lymph nodes (P = 0.0452). SIR administration also enhanced the protection by reducing the parasite load in the spleen (P = 0.0004). Vaccinated animals with or without SIR co-treatment showed lower IFN-γ expression levels than those found in the spleen of control animals. mRNA expression levels of NOS2 and IL-10 were found to be significantly higher in the vaccinated plus SIR treated group.. Co-administration of SIR enhances a DNA vaccination regimen against L. infantum, improving the reduction of parasite load in skin, lymph node and spleen. The analysis of immune markers in the spleen after challenge suggests that the trend to recover naïve levels of IFN-γ and IL-10, and the concurrent higher expression of NOS2, may be responsible for the protection induced by our vaccine co-administered with SIR.

Topics: Animals; Antibodies, Protozoan; Cricetinae; Cytokines; Immunization; Immunologic Factors; Leishmania infantum; Leishmaniasis, Visceral; Male; Mesocricetus; Parasite Load; Plasmids; Protozoan Proteins; Sirolimus; Spleen; Vaccines, DNA

Leishmania-induced interleukin-12 (IL-12) expression is negatively regulated by the phosphatidylinositol 3-kinase (PI3K) and extracellular signal regulated kinase (ERK) 1/2 pathways in human monocyte derived macrophages (MDMs). To extend these studies, we examined the pathways downstream from PI3K in L. donovani-induced reciprocal regulation of IL-12/IL-10 axis in THP-1-derived macrophages. We show for the first time that in THP-1-derived macrophages and human monocytes, mTOR inhibition by rapamycin reversed L. donovani-induced IL-12 and IL-10 modulation. L. donovani-induced phosphorylation of P70S6K, a correlate of mTOR activity, in TLR-stimulated THP-1 derived macrophages. This increase in P70S6K phosphorylation was completely blocked by rapamycin (mTOR inhibitor) and partially by wortmannin (PI3K inhibitor). These observations suggest that a PI3K independent pathway is operative in the modulation of IL-12 and IL-10. Blocking of TLR2 significantly attenuated IL-10 induced by the parasite, but did not affect IL-12 production. Thus, our data suggests that intracellular network of PI3K and mTOR pathway control IL-12/IL-10 modulation by L. donovani. mTOR inhibitors may be attractive molecules to reverse this modulation and may result in control of disease.

Topics: Animals; Cell Line; Humans; Interleukin-10; Interleukin-12; Leishmania donovani; Leishmaniasis, Visceral; Macrophages; Monocytes; Phosphatidylinositol 3-Kinases; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases

Malignancies and opportunistic infections are frequently observed after solid-organ transplantation. Their occurrence strongly affects recipient survival. We report the case of a 29-year-old Tunisian kidney-recipient who was diagnosed simultaneously with post-transplant lymphoproliferative disease (PTLD) and visceral leishmaniasis (VL). Withdrawal of immunosuppressive therapy together with antiparasitic treatment using liposomal amphotericin B, and anti-CD20 antibodies medication resulted in cure of leishmaniasis and remission from PTLD. This case is of clinical interest because of the uncommon association of VL with PTLD after solid organ transplantation. It is also original by the favourable outcome of VL and PTLD, both known as life-threatening diseases. Also, it illustrates the predisposing role of immunosuppressive therapy in occurrence of opportunistic infections and malignancies after solid organ transplantation.

Topics: Adult; Amphotericin B; Antibodies, Monoclonal, Murine-Derived; Antiprotozoal Agents; Antiviral Agents; Epstein-Barr Virus Infections; Ganciclovir; Humans; Immunocompromised Host; Immunosuppressive Agents; Kidney Transplantation; Leishmaniasis, Visceral; Lymphoproliferative Disorders; Male; Meglumine; Meglumine Antimoniate; Opportunistic Infections; Organometallic Compounds; Postoperative Complications; Remission Induction; Rituximab; Sirolimus