Metabolic manipulation of host cells by intracellular pathogens is currently recognized to play an important role in the pathology of infection. Nevertheless, little information is available ...regarding mitochondrial energy metabolism in Leishmania infected macrophages. Here, we demonstrate that during L. infantum infection, macrophages switch from an early glycolytic metabolism to an oxidative phosphorylation, and this metabolic deviation requires SIRT1 and LKB1/AMPK. SIRT1 or LBK1 deficient macrophages infected with L. infantum failed to activate AMPK and up-regulate its targets such as Slc2a4 and Ppargc1a, which are essential for parasite growth. As a result, impairment of metabolic switch caused by SIRT1 or AMPK deficiency reduces parasite load in vitro and in vivo. Overall, our work demonstrates the importance of SIRT1 and AMPK energetic sensors for parasite intracellular survival and proliferation, highlighting the modulation of these proteins as potential therapeutic targets for the treatment of leishmaniasis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Plants are increasingly exposed to events of elevated temperature and water deficit, which threaten crop productivity. Understanding the ability to rapidly recover from abiotic stress, restoring ...carbon assimilation and biomass production, is important to unravel crop climate resilience. This study compared the photosynthetic performance of two Triticum aestivum L. cultivars, Sokoll and Paragon, adapted to the climate of Mexico and UK, respectively, exposed to 1‐week water deficit and high temperatures, in isolation or combination. Measurements included photosynthetic assimilation rate, stomatal conductance, in vitro activities of Rubisco (EC 4.1.1.39) and invertase (INV, EC 3.2.1.26), antioxidant capacity and chlorophyll a fluorescence. In both genotypes, under elevated temperatures and water deficit (WD38°C), the photosynthetic limitations were mainly due to stomatal restrictions and to a decrease in the electron transport rate. Chlorophyll a fluorescence parameters clearly indicate differences between the two genotypes in the photoprotection when subjected to WD38°C and showed faster recovery of Paragon after stress relief. The activity of the cytosolic invertase (CytINV) under these stress conditions was strongly related to the fast photosynthesis recovery of Paragon. Taken together, the results suggest that optimal sucrose export/utilization and increased photoprotection of the electron transport machinery are important components to limit yield fluctuations due to water shortage and elevated temperatures.
Interannual and local fluctuations in wheat crop yield are majorly explained by abiotic constraints. Heatwaves and drought, which are among the top stressors, commonly co-occur, and their frequency ...is increasing with global climate change. High-throughput methods were optimised to phenotype wheat plants under controlled water deficit and high temperature, with the aim to identify phenotypic traits conferring adaptative stress responses. Wheat plants of 10 genotypes were grown in a fully automated plant facility under 25/18ºC day/night for 30 days, and then the temperature was increased for seven days (38/31ºC day/night) while maintaining half of the plants well irrigated and half at 30% field capacity. Thermal and multispectral images and pot weights were registered twice daily. At the end of the experiment, key metabolites and enzyme activities from the carbohydrate and antioxidant metabolisms were quantified. Regression machine learning models were successfully established to predict plant biomass using image-extracted parameters. Evapotranspiration traits expressed significant genotype-environment interactions (GxE) when acclimatization to stress was continuously monitored. Consequently, transpiration efficiency was essential to maintain the balance between water-saving strategies and biomass production in wheat under water deficit and high temperature. Stress tolerance included changes in the carbohydrate metabolism, particularly in the sucrolytic and glycolytic pathways, and in the antioxidant metabolism. The observed genetic differences in sensitivity to high temperature and water deficit can be exploited in breeding programs to improve wheat resilience to climate change.
Exhibiting a red-shifted absorption/scattering feature compared to conventional plasmonic metals, titanium nitride nanoparticles (TiN NPs) look as very promising candidates for biomedical ...applications, but these applications are still underexplored despite the presence of extensive data for conventional plasmonic counterparts. Here, we report the fabrication of ultrapure, size-tunable TiN NPs by methods of femtosecond laser ablation in liquids and their biological testing. We show that TiN NPs demonstrate strong and broad plasmonic peak around 640-700 nm with a significant tail over 800 nm even for small NPs sizes (<7 nm). In vitro tests of laser-synthesized TiN NPs on cellular models evidence their low cytotoxicity and excellent cell uptake. We finally demonstrate a strong photothermal therapy effect on U87-MG cancer cell cultures using TiN NPs as sensitizers of local hyperthermia under near-infrared laser excitation. Based on absorption band in the region of relative tissue transparency and acceptable biocompatibility, laser-synthesized TiN NPs promise the advancement of biomedical modalities employing plasmonic effects, including absorption/scattering contrast imaging, photothermal therapy, photoacoustic imaging and SERS.
Abstract
Under perturbing conditions such as infection with
Leishmania
, a protozoan parasite living within the phagosomes in mammalian macrophages, cellular and organellar structures, and metabolism ...are dynamically regulated for neutralizing the pressure of parasitism. However, how modulations of the host cell metabolic pathways support
Leishmania
infection remains unknown. Herein, we report that lipid accumulation heightens the susceptibility of mice to
L. donovani
infection and promotes resistance to first‐line anti‐leishmanial drugs. Despite being pro‐inflammatory, the in vitro generated uninfected lipid‐laden macrophages (LLMs) or adipose‐tissue macrophages (ATMs) display lower levels of reactive oxygen and nitrogen species. Upon infection, LLMs secrete higher IL‐10 and lower IL‐12p70 cytokines, inhibiting CD4
+
T cell activation and Th1 response suggesting a key modulatory role for intramacrophage lipid accumulation in anti‐leishmanial host defence. We, therefore, examined this causal relationship between lipids and immunomodulation using an in vivo high‐fat diet (HFD) mouse model. HFD increased the susceptibility to
L. donovani
infection accompanied by a defective CD4
+
Th1 and CD8
+
T cell response. The white adipose tissue of HFD mice displays increased susceptibility to
L. donovani
infection with the preferential infection of F4/80
+
CD11b
+
CD11c
+
macrophages with higher levels of neutral lipids reserve. The HFD increased resistance to a first‐line anti‐leishmanial drug associated with a defective adaptive immune response. These data demonstrate that the accumulation of neutral lipids contributes to susceptibility to visceral leishmaniasis hindering host‐protective immune response and reducing the efficacy of antiparasitic drug therapies.
Trypanosomiasis is a parasitic disease affecting both humans and animals
in the form of Human African Trypanosomiasis and Nagana disease,
respectively. Anemia is one of the most common symptoms of
...trypanosomiasis, and if left unchecked can cause severe complications and
even death. Several factors have been associated with the development of
this anemia, including dysregulation of iron homeostasis, but little is known
about the molecular mechanisms involved. Here, using murine models, we
study the involvement of hepcidin, the key regulator of iron metabolism and
an important player in the development of anemia of inflammation. Our
data show two stages for the progression of anemia, to which hepcidin contributes
a first stage when anemia develops, with a likely cytokine-mediated
stimulation of hepcidin and subsequent limitation in iron availability and
erythropoiesis, and a second stage of recovery, where the increase in hepcidin
then declines due to the reduced inflammatory signal and increased
production of erythroid regulators by the kidney, spleen and bone marrow,
thus leading to an increase in iron release and availability, and enhanced erythropoiesis.
In agreement with this, in hepcidin knockout mice, anemia is
much milder and its recovery is complete, in contrast to wild-type animals
which have not fully recovered from anemia after 21 days. Besides all other
factors known to be involved in the development of anemia during trypanosomiasis,
hepcidin clearly makes an important contribution to both its
development and recovery.
Canine leishmaniasis is a major veterinary issue and also a public health challenge due to its zoonotic potential. In this context, serological evaluation is essential for Canine leishmaniasis ...management. Several serological alternatives, such as rapid diagnostic tests, enzyme-linked immunosorbent assay (ELISA) and immunofluorescence antibody test (IFAT), are well established. In fact, the capacity of distinct tests and antigens, evaluated by their sensitivity and specificity, to detect disease is normally considered sufficient for diagnosing Canine leishmaniasis. In this context, we evaluated the seropositivity using 8 different serological tests (ELISA with Leishmania recombinant proteins (rK39, LicTXNPx); soluble promastigote Leishmania antigens (SPLA); commercial ELISA test) in 82 clinically suspect animals from Northern Portugal. The obtained serological data originated 50% of inconclusive serological information with a mixture of seropositive and seronegative results for individual animals. Cut-off independent risk groups were then generated from the serological data to evaluate the clustering of the samples. This analysis originated risk groups that correlated with the most seropositive samples, suggesting that this method might be used, in a cut-off independent manner, to improve conventional serological evaluation. Ultimately, given that no test prioritization exists, the use of any single serological test increases the potential for misdiagnosis, along with all associated risks for the dog as well as public health. The use of a cut-off independent analysis has the potential to improve the predictive values of these tests, enabling a more accurate evaluation of the dog's condition.
Leishmania spp. are intracellular parasitic protozoa responsible for a group of neglected tropical diseases, endemic in 98 countries around the world, called leishmaniasis. These parasites have a ...complex digenetic life cycle requiring a susceptible vertebrate host and a permissive insect vector, which allow their transmission. The clinical manifestations associated with leishmaniasis depend on complex interactions between the parasite and the host immune system. Consequently, leishmaniasis can be manifested as a self-healing cutaneous affliction or a visceral pathology, being the last one fatal in 85-90% of untreated cases. As a result of a long host-parasite co-evolutionary process, Leishmania spp. developed different immunomodulatory strategies that are essential for the establishment of infection. Only through deception and manipulation of the immune system, Leishmania spp. can complete its life cycle and survive. The understanding of the mechanisms associated with immune evasion and disease progression is essential for the development of novel therapies and vaccine approaches. Here, we revise how the parasite manipulates cell death and immune responses to survive and thrive in the shadow of the immune system.
Fluorescence is a very promising radioactive-free technique for functional imaging in small animals and, in the future, in humans. However, most commercial near-infrared dyes display poor optical ...properties, such as low fluorescence quantum yields and short fluorescence lifetimes. In this paper, we explore whether the encapsulation of infrared cyanine dyes within the core of lipid nanoparticles (LNPs) could improve their optical properties. Lipophilic dialkylcarbocyanines DiD and DiR are loaded very efficiently in 30-35-nm-diam lipid droplets stabilized in water by surfactants. No significant fluorescence autoquenching is observed up to 53 dyes per particle. Encapsulated in LNP, which are stable for more than one year at room temperature in HBS buffer (HEPES 0.02 M, EDTA 0.01 M, pH 5.5), DiD and DiR display far improved fluorescence quantum yields Phi (respectively, 0.38 and 0.25) and longer fluorescence lifetimes tau (respectively, 1.8 and 1.1 ns) in comparison to their hydrophilic counterparts Cy5 (Phi=0.28, tau=1.0 ns) and Cy7 (Phi=0.13, tau=0.57 ns). Moreover, dye-loaded LNPs are able to accumulate passively in various subcutaneous tumors in mice, thanks to the enhanced permeability and retention effect. These new fluorescent nanoparticles therefore appear as very promising labels for in vivo fluorescence imaging.
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