Leishmanicidal and healing effects of 3ß,6ß,16ß-trihydroxy lup-20 (29)-ene isolated from Combretum leprosum on Leishmania braziliensis infection in vitro and in vivo.

Treatment of cutaneous leishmaniasis depends on drugs that potentially cause serious side effects and resistance. Thus, topical therapies are attractive alternatives to the drugs currently used. 3ß, 6ß, 16ß-trihydroxylup-20 (29)-ene is a lupane triterpene isolated from Combretum leprosum Mart. leaves (CLF-1), with reports of in vitro antileishmanial effect against L. amazonensis and to promote lesion healing in animal model. Herein, we evaluated the in vitro and in vivo antileishmanial and healing effects of CLF-1 against L. braziliensis. CLF-1 treatment showed low toxicity in macrophages and significantly reduced parasite load in vitro. CLF-1 induced higher IL-12 and TNF-α production and more discrete IL-4 and IL-10 production. For in vivo evaluation, a CLF-1 cream formulation was prepared to treat hamsters infected with L. braziliensis. CLF-1 treatment was able to reduce parasite load of the infected skin and lymph node more efficiently than the conventional treatment. Histopathological analysis indicated a strong inflammatory response accompanied by an important healing response. Data from this study indicate that topical CLF-1 treatment was effective and non-toxic in L. braziliensis infected hamsters suggesting its potential for further development as a future therapeutic intervention.

CXCL10 treatment promotes reduction of IL-10+ regulatory T (Foxp3+ and Tr1) cells in the spleen of BALB/c mice infected by Leishmania infantum.

American visceral leishmaniasis is caused by the protozoan Leishmania infantum. The control of the disease depends on the magnitude of the Th1 cell response and IL-10 producing regulatory T cells. Administration of chemokine, such as CXCL10, has shown promising results in the leishmaniasis treatment. Previous studies from our group have shown that CXCL10 induces a reduction in parasite burden in the spleen and a decrease in IL-10 and TGF-ß production in L. infantum-infected BALB/c mice. This work investigated whether CXCL10-treatment reduces IL-10 + Treg cell populations (CD4+CD25+Foxp3+ and Tr1) and induces morphological changes in the spleen. BALB/c mice were infected and treated or not with CXCL10 on the 1st, 3rd and 7th days of infection. CXCL10-treatment was able to reduce the parasite load in the spleen in L. infantum-infected BALB/c mice and this decrease in the number of parasites correlated with the decrease in size of this organ in treated animals compared to untreated animals. 7, 23, and 45 days post-treatment (p.t.), the phenotype and frequency of IL-10 + Treg cells were evaluated by flow cytometry, and the morphological changes of the spleen were analyzed by optical microscopy. After 7 and 23 days p.t., CXCL10-treated animals showed a significant reduction of CD25-Foxp3-IL-10+ (Tr1) cells in the spleen when compared to untreated animals, whereas CD4+CD25+Foxp3+IL-10+ Treg cells reduced later at 23rd and 45th days p.t. Furthermore, while untreated animals showed a significant positive correlation between IL-10 production and Tr1 cells, in CXCL10-treated group this correlation was negative. Thus, these findings show that treatment with CXCL10 chemokine in L. infantum-infected BALB/c mice results in suppression of IL10+ Treg (Foxp3+ and Tr1) cells in the spleen, associated with a reduction in parasite load and splenomegaly.