Upregulation of ATP6V0D2 benefits intracellular survival of Leishmania donovani in erythrocytes-engulfing macrophages.

Visceral leishmaniasis (VL) is the most severe type of leishmaniasis which is caused by infection of Leishmania donovani complex. In the BALB/c mouse model of VL, multinucleated giant cells (MGCs) with heavy parasite infection consist of the largest population of hemophagocytes in the spleen of L. donovani-infected mice, indicating that MGCs provide the parasites a circumstance beneficial for their survival. Although ATP6V0D2 is a demonstrated factor inducing the formation of hemophagocytic MGCs during L. donovani infection, functions of this protein in shaping the infection outcome in macrophages remain unclear. Here we evaluated the influence of upregulated ATP6V0D2 on intracellular survival of the parasites. L. donovani infection-induced hemophagocytosis of normal erythrocytes by macrophages was suppressed by RNAi-based knockdown of Atp6v0d2. The knockdown of Atp6v0d2 did not improve the survival of amastigotes within macrophages when the cells were cultured in the absence of erythrocytes. On the other hand, reduced intracellular survival of amastigotes in macrophages by the knockdown was observed when macrophages were supplemented with antibody-opsonized erythrocytes before infection. There, increase in cytosolic labile iron pool was observed in the L. donovani-infected knocked-down macrophages. It suggests that ATP6V0D2 plays roles not only in upregulation of hemophagocytosis but also in iron trafficking within L. donovani-infected macrophages. Superior access to iron in macrophages may be how the upregulated expression of the molecule brings benefit to Leishmania for their intracellular survival in the presence of erythrocytes.

Evaluation of ex vivo human immune response against candidate antigens for a visceral leishmaniasis vaccine.

People cured from visceral leishmaniasis (VL) develop protection mediated by Th1-type cellular responses against new infections. We evaluated cytokine responses against 6 defined candidate vaccine antigens in 15 cured VL subjects and 5 healthy endemic controls with no evidence of previous exposure to Leishmania parasites. Of the 6 cytokines examined, only interferon-gamma (IFN-gamma) differentiated cured VL patients from non-exposed individuals, with cured patients mounting a significantly higher IFN-gamma response to a crude parasite antigen preparation. Among candidate vaccine antigens tested, the largest number of cured subjects recognized cysteine proteinase B, leading to heightened IFN-gamma responses, followed by sterol 24-c-methyltransferase. These two antigens were the most immunogenic and protective antigens in a murine VL model, indicating a relationship between T cell recall responses of humans cured from VL and protective efficacy in an experimental model. Further studies may help prioritize antigens for clinical development of a subunit vaccine against VL.

Relationship between nutritional therapy and surgery in Crohn's disease.

BACKGROUND/AIMS: Crohn's disease is often refractory and some patients require repeated surgical treatment. Nutritional therapy with an elemental diet has been reported effective in improving nutritional state and suppressing inflammation, and might be expected to assist in minimizing the need for surgery. We evaluated the relationship between an elemental diet and the period that patients spent without intestinal resection. METHODOLOGY: A total of 153 patients with Crohn's disease who visited our hospital from July, 1999 to July, 2005 were enrolled. The relationship between the caloric content of an elemental diet and surgery as an endpoint was examined using Cox regression analysis. Cumulative non-operation rates were calculated by the Kaplan-Meier method. Statistical significance was determined using the log-rank test. RESULTS: Among patients with jejunoileal involvement, patients receiving an elemental diet providing 900 kcal or more per day showed a statistically significant improvement in cumulative non-operation rate. Among those without jejunoileal involvement, in contrast, the cumulative non-operation rate did not differ among those receiving an elemental diet of less or more than 900 kcal per day. CONCLUSIONS: The use of an elemental diet of 900 kcal per day may be effective in avoiding surgery in patients with jejunoileal lesions. This diet may be useful in improving long-term convalescence in these patients.

Monitoring the effects of component structure and source on formulation stability and adjuvant activity of oil-in-water emulsions.

Oil-in-water emulsions have shown promise as safe and effective adjuvant formulations for vaccines. In particular, formulations consisting of metabolizable oils such as shark-derived squalene and detergents such as egg phosphatidylcholine have been used to produce stable vaccine emulsion formulations. However, there is an emphasis in pharmaceutical regulatory bodies on using synthetic or plant-derived components from sustainable sources instead of animal-derived components. This study compares the physicochemical properties and biological efficacy of emulsions consisting of oil and detergent components from animal, plant, and synthetic sources. In particular, effects of component structure and source on emulsion stability and biological activity are examined. It is shown that oil-in-water emulsions using animal-derived components can be substituted with synthetic or plant-derived materials while still exhibiting satisfactory physicochemical and biological properties.