Behavior of two Leishmania infantum strains—evaluation of susceptibility to antimonials and expression of microRNAs in experimentally infected J774 macrophages and in BALB/c mice

Abstract

Strains of the same Leishmania parasite species, isolated from different host organisms, may exhibit unique infection profiles and induce a change in the expression of microRNAs among host macrophages and in model host mice. MicroRNAs (MiR) are endogenous molecules of about 22 nucleotides that are involved in many regulatory processes, including the vertebrate host immune response. In this respect, the infectivity and susceptibility to antimonials of two L. infantum strains, BH46, isolated from human, and OP46, isolated from symptomatic dog, were characterized in J774 macrophages and BALB/c mice. Parasite burden was assessed in the liver, spleen, and bone marrow using the serial limiting dilution technique. A higher parasite burden was observed in the spleen and bone marrow of animals infected with OP46 compared to BH46 strain. Our results also showed that OP46 was less susceptible to the antimonials. In addition, miR-122 and miR-155 expression was evaluated in the liver and J774 macrophages, and in spleens from infected animals, respectively. An increase was observed in the expression of miR-155 in J774 macrophages infected with both strains compared to uninfected cells, with a higher expression in cells infected with OP46. However, no difference in the expression of miR-122 and miR-155 was observed in the infected animals. Thus, this study shows that OP46 was more infective for mice, it caused a higher increase in miR-155 expression in infected macrophages and was less susceptible to the antimonials evaluated. These data suggest that alteration in miR-155 level likely plays a role in regulating the response to L. infantum.

Induction of miR 21 impairs the anti-Leishmania response through inhibition of IL-12 in canine splenic leukocytes

“…Differential expression of miR 122 was demonstrated in mice macrophages infected by L . infantum [31], in human macrophages, infected by L . donovani , members of the miR 30A-3p family were misregulated [15], suggesting that there is variation in miRNA response to Leishmania spp.…”

Expression of MicroRNA of Macrophages Infected with Attenuated Leishmania major Parasite

“…36 Silva et al showed alterations in the miR-155 level probably contributes to the regulation of responses to Leishmania infantum. 37 In their research, Singh et al presented the current modulatory contribution of the host microRNA (miR30a-3p) in regulating the host cell macroautophagy/autophagy following the infections with L. donovani. 19 Wendlandt demonstrated that logarithmic phase of promastigote multiplying processes, different miRNAs, such as miR-200b, let-7b, miR-339-5p, miR-423-5p, and miR-744, noticeably changed in the infected macrophages.…”

Liver infusion tryptose (LIT): the best choice for growth, viability, and infectivity of Leishmania infantum parasites

“…infantum promastigotes cultivated in Grace’s medium demonstrated a lower percentage of infected macrophages but high parasite load (as shown by optical microscopy and flow cytometry analysis). This can be explained by the nature of the medium which is largely used in many studies to induce infection in animal models (da Silva Jr. et al 2015 ; Silva et al 2018 ; Siripattanapipong et al 2019 ). Based on our data, we can suggest that Grace’s medium, instead of inducing procyclic promastigotes, probably induces the formation of metacyclic promastigotes that explains the high parasite load in the infected macrophages in vitro.…”