Biology subjects

Giorgio, S.

Publications and source records attributed to Giorgio, S..

3 recordsLinked to original sources

bioRxiv2025

Impact of Bacterial Membrane Vesicles on Cellular Responses in Leishmania amazonensis-Infected Macrophages In Vitro

Leishmania amazonensis is an intracellular protozoan parasite and the main cause of Localized Cutaneous Leishmaniasis (LCL). A practical problem that can worsen the condition of infected individuals is secondary co-infection caused by opportunistic bacteria. This study evaluated the influence of Bacterial Membrane Vesicles (BMVs) from Pseudomonas aeruginosa and Staphylococcus aureus--both commonly associated with LCL--on macrophages previously infected with L. amazonensis. The diameter and concentration of BMVs were consistent with previous findings. We assessed infection dynamics, macrophage viability, and cytokine production. Results showed significant reductions in these parameters when L. amazonensis-infected macrophages were subsequently treated with BMVs, compared to the control group (infected but not treated with BMVs). Quantification of IL-2, IL-4, IL-6, IL-10, IL-17A, IFN-{gamma}, and TNF- revealed elevated levels of the last cytokine, suggesting an inflammatory response. Co-cultures treated with BMVs from P. aeruginosa (POMVs) exhibited a more pronounced inflammatory profile--marked by higher IL-1{beta} and TNF- concentrations--compared to those treated with BMVs from S. aureus (SEVs). IL-4 and IL-6 levels remained low relative to IL-1{beta} and TNF-. In conclusion, our data suggest that macrophage infection with L. amazonensis followed by exposure to bacterial MVs simulates a host-parasite-bacterial interaction, inducing strong immunogenic and inflammatory responses, which may represent potential targets for future vaccine strategies.

microbiology↗

bioRxiv2024

Uptake and survival of Leishmania amazonensis in Acanthamoeba castellanii: An infection organism model?

Leishmaniasis is a neglected tropical disease. Parasite strategies and the evaluation of drugs and vaccines are inferred from studies carried out using mouse models and macrophages. The development of model organisms with no ethical restrictions will contribute to our knowledge of leishmaniasis. Acanthamoeba castellanii, a free-living protozoan, is known to interact with various microorganisms. In this study, the interaction between the amoeba A. castellanii and the trypanosomatid Leishmania amazonensis was investigated by combining quantitative kinetics analysis, optical, fluorescence, electronic, confocal, and live video microcopy. We sought to standardize protocols for the co-culture; the optimal experimental conditions were: RPMI medium + 10% SFB at 26{degrees}C. L. amazonensis invades A. castellanii through its acanthopods, and the promastigotes interact with the trophozoites via their flagellum, which also occurs when parasites infect mammalian macrophages. The forms of L. amazonensis inside the amoeba become rounded and lose their flagellum; they are similar to amastigotes. These round forms were isolated from trophozoites after 3 h of co-culture and differentiated into promastigotes, demonstrating their viability inside amoeba. The percentage of amoebas with L. amazonensis was reduced overtime. Thus, considering that A. castellanii can clear Leishmania, this interaction could serve as an effective model of cellular leishmanicidal mechanisms.

cell biology↗

bioRxiv2023

The impact of knocking out the Leishmania major telomerase RNA (LeishTER): from altered cell proliferation to decreased parasite infectivity

The telomerase RNA, TER, is an intrinsic component of the telomerase ribonucleoprotein complex. It contains the telomere template sequence copied by the enzyme during telomere elongation. This unique molecule shows divergent nucleotide sequences but a more conserved secondary structure containing domains involved with telomerase assembly and biogenesis. The present work aims to characterize the biological roles played by the Leishmania TER component (LeishTER) in parasite homeostasis. We generated double knockout (LmTER-/-) parasites, which showed a distinct growth pattern at early passages, characterized by lower density and an extended stationary phase compared to the control. Although this pattern normalized after multiple in vitro passages, ablation of LeishTER affected cell division and proliferation, with cells arrested at the G0/G1 phase. Progressive telomere shortening was also observed during continuous passages, along with a reduction in the expression of TERRA29. Complementation with the episomal expression of LeishTER did not restore telomere length to the control levels, corroborating preliminary results showing that the overexpression of TER has a dominant negative effect on parasite lifespan. LmTER-/- also presented a higher percentage of gamma-H2A phosphorylation, likely due to stalled replication forks since no DNA damage was observed. Also, no plasma membrane modifications were detected, but pro-survival autophagic signals were present. Intriguingly, LmTER-/- retained the ability to transform into metacyclic forms, although its in vitro infectivity and growth inside the host cell were compromised. Together, these results highlight the importance of TER in parasite lifespan and open a discussion about its potential as a drug target against Leishmania.

molecular biology↗