MicroRNAs are small non-coding RNAs that regulate cellular processes by the post-transcriptional regulation of gene expression, including immune responses. The shift in the miRNA profiling of murine macrophages infected with Leishmania amazonensis can change inflammatory response and metabolism. L-arginine availability and its conversion into nitric oxide by nitric oxide synthase 2 (Nos2) or ornithine (a polyamine precursor) by arginase 1/2 regulate macrophage microbicidal activity. This work aimed to evaluate the function of miR-294, miR-301b, and miR-410 during early C57BL/6 bone marrow-derived macrophage infection with L. amazonensis. We observed an upregulation of miR-294 and miR-410 at 4 h of infection, but the levels of miR-301b were not modified. This profile was not observed in LPS-stimulated macrophages. We also observed decreased levels of those miRNAs target genes during infection, such as Cationic amino acid transporters 1 (Cat1/Slc7a1), Cat2/Slc7a22 and Nos2; genes were upregulated in LPS stimuli. The functional inhibition of miR-294 led to the upregulation of Cat2 and Tnfa and the dysregulation of Nos2, while miR-410 increased Cat1 levels. miR-294 inhibition reduced the number of amastigotes per infected macrophage, showing a reduction in the parasite growth inside the macrophage. These data identified miR-294 and miR-410 biomarkers for a potential regulator in the inflammatory profiles of microphages mediated by L. amazonensis infection. This research provides novel insights into immune dysfunction contributing to infection outcomes and suggests the use of the antagomiRs/inhibitors of miR-294 and miR-410 as new therapeutic strategies to modulate inflammation and to decrease parasitism.

Polyamines are molecules involved in macrophage activation and polarization in response to pathogens. The interaction with Leishmania promotes modulation of macrophage immune response to favor arginine deviation to polyamines production, leading to parasite survival. Polyamine levels are a potential modulator of growth factors, driving cells to proliferation, wound healing, oxidative stress, or regulating translation . Here, we investigate the impact of L-arginine and polyamines in the transcriptional regulation of genes involved in arginine metabolization and pro-inflammatory response to L. amazonensis in murine BALB/c macrophages. We found that supplementation with L-arginine is insufficient to modulate macrophage gene expression and infection. Polyamine supplementation altered nitric oxide synthase (Nos2) and nitric oxide (NO) production, as well as other macrophage enzymes. Putrescine supplementation increased transcript levels of polyamine metabolism-related genes Arginase 2 (Arg2), Spermidine synthase (SpdS), and Spermine synthase (SpmS) in both uninfected and L. amazonensis infected macrophages. Putrescine increased Nos2 expression without leading to NO production, while L-arginine plus spermine led to production of NO in uninfected macrophages. Besides, L-arginine supplementation reduced the levels of Il-1b during infection, and L-arginine or L-arginine plus putrescine increased Mcp1 at 24h of infection. The percentage of infected macrophages was lower after putrescine, spermidine, and spermine supplementation than L-arginine supplementation. Our data showed that the polyamines shift L-arginine-metabolism related-genes on BALB/c macrophages and affect infection by L. amazonensis.

Leishmania is a protozoan that causes leishmaniasis, a neglected tropical disease with clinical manifestations classified as cutaneous, mucocutaneous, and visceral leishmaniasis. In the infection context, the parasite can modulate macrophage gene expression affecting the microbicidal activity and immune response. The metabolism of L-arginine into polyamines putrescine, spermidine, and spermine reduces nitric oxide (NO) production, favoring Leishmania survival. Here, we investigate the effect of supplementation with L-arginine and polyamines in infection of murine BALB/c macrophages by L. amazonensis and in the transcriptional regulation of genes involved in arginine metabolism and proinflammatory response. We showed a reduction in the percentage of infected macrophages upon putrescine supplementation compared to L-arginine, spermidine, and spermine supplementation. Unexpectedly, deprivation of L-arginine increased nitric oxide synthase (Nos2) gene expression without changes in NO production. Putrescine supplementation increased transcript levels of polyamine metabolism-related genes Arg2, ornithine decarboxylase (Odc1), Spermidine synthase (SpdS), and Spermine synthase (SpmS), but reduced Arg1 in L. amazonensis infected macrophages, while spermidine and spermine promoted opposite effects. Putrescine increased Nos2 expression without leading to NO production, while L-arginine plus spermine led to NO production in uninfected macrophages, suggesting that polyamines can induce NO production. Besides, L-arginine supplementation reduced Il-1b during infection, and L-arginine or L-arginine plus putrescine increased Mcp1 at 24h of infection, suggesting that polyamines availability can interfere with cytokine/chemokine production. Our data showed that putrescine shifts L-arginine-metabolism related-genes on BALB/c macrophages and affects infection by L. amazonensis.

Aos meus pais, Marcia e Angelo e minhas avós Edna e Valdomira, agradeço por sempre me apoiarem e confiarem em mim. Agradeço a minha orientadora, Sandra Marcia Muxel, e a vida, por esse encontro tão importante e que deu super certo. Meus amigos de São Paulo, Olívia, Luan, Lídia, Lucas, Clei, Guilherme, Sthephany, Beatriz e Suemy, tão importantes desde o início do mestrado.As pessoas da minha vida que amo, sinto falta e que mesmo distantes pelas circunstâncias dei um jeito de manter na lembrança, sempre perto,