Targeting of immunostimulatory DNA cures experimental visceral leishmaniasis through nitric oxide up‐regulation and T cell activation

Abstract

Active targeting of CpG-containing oligodeoxynucleotide (CpG-ODN) to macrophages was studied by incorporating it in mannose-coated liposomes, using visceral leishmaniasis as the model macrophage disease. Mannosylated liposomal CpG-ODN was more effective than liposomal or free CpG-ODN in inhibiting amastigote multiplication within macrophages. Moreover, in a 60-day mouse model of visceral leishmaniasis, complete elimination of spleen parasite burden was achieved by mannosylated liposomal CpG-ODN, compared to 62% and 81% parasite suppression by free and liposomal ODN, respectively, at a similar dose. Although in vitro exposure of CpG-ODN did not induce marked nitric oxide (NO) generation by macrophages, considerably enhanced amount of NO was generated by macrophages of CpG-ODN-treated animals. Their splenocytes secreted soluble factors required for the induction of NO generation, and the increased NO generation was paralleled by an increase in antileishmanial activity. Inducible NO generation was suppressed by treating splenocyte supernatants with anti-IFN-+ or anti-IL-12 antibodies, whereas in vivo administration of these anti-cytokine Ab along with CpG-ODN reversed protection against infection. CpG-ODN treatment resulted in reduced levels of IL-4, but increased levels of IFN-+ , IL-12 and inducible NO synthase in infected spleen cells, which was magnified by encapsulation in mannose-coated liposomes. This targeted treatment was not only curative, but it also imparted resistance to reinfection. These results represent a general approach for intracellular targeting of CpG-ODN, which effectively enhances its therapeutic potential in redirecting curative Th1 responses in Th2-driven disorders.

Hepatoprotective and neuroprotective activity of liposomal quercetin in combating chronic arsenic induced oxidative damage in liver and brain of rats

“…Hepatoprotective effect of a single injection of galactosylated liposomal quercetin on acute arsenite treated rats has been already studied by us in our previous observation (Mandal et al 2007). The same observation was made by Datta et al, 2003. They demonstrated that the liposome-entrapped compound interacts with target cells at a much faster rate than that of free components.…”

TLR9 Agonists Oppositely Modulate DNA Repair Genes in Tumor versus Immune Cells and Enhance Chemotherapy Effects

“…with CpG-ODN (26). Spleen cells were chosen for this analysis on the basis of previous studies establishing that the spleen accurately reflects the breadth of immunity induced by CpG-ODN in vivo (27)(28)(29)(30)(31)(32). Expression levels of mRNA in mouse spleen cells were monitored by microarray at different times after in vivo CpG-ODN treatment.…”

Regulatory Actions of Toll-Like Receptor 2 (TLR2) and TLR4 in Leishmania donovani Infection in the Liver

“…The latter have shown that expression of TLR2 and TLR4 mRNA in the spleen correlates with parasite load in L. infantum-infected BALB/c mice (25) and that prophylactic and/or therapeutic injections of TLR2 (26,27), TLR4 (28), or TLR9 agonists (29)(30)(31) enhance resistance in L. donovani-infected hamsters or BALB/c mice. Directly generated in vivo information is limited.…”