There is substantial experimental evidence to indicate that Leishmania infections that are transmitted naturally by the bites of infected sand flies differ in fundamental ways from those initiated by ...needle inocula. We have used flow cytometry and intravital microscopy (IVM) to reveal the heterogeneity of sand fly transmission sites with respect to the subsets of phagocytes in the skin that harbor L. major within the first hours and days after infection. By flow cytometry analysis, dermis resident macrophages (TRMs) were on average the predominant infected cell type at 1 hr and 24 hr. By confocal IVM, the co-localization of L. major and neutrophils varied depending on the proximity of deposited parasites to the presumed site of vascular damage, defined by the highly localized swarming of neutrophils. Some of the dermal TRMs could be visualized acquiring their infections via transfer from or efferocytosis of parasitized neutrophils, providing direct evidence for the "Trojan Horse" model. The role of neutrophil engulfment by dermal TRMs and the involvement of the Tyro3/Axl/Mertk family of receptor tyrosine kinases in these interactions and in sustaining the anti-inflammatory program of dermal TRMs was supported by the effects observed in neutrophil depleted and in Axl-/-Mertk-/- mice. The Axl-/-Mertk-/- mice also displayed reduced parasite burdens but more severe pathology following L. major infection transmitted by sand fly bite.
The origin and functional specialization of dermal macrophages in cutaneous infections have been little studied. In this paper, we show that a strain of
(
Seidman LmSd) that produces nonhealing ...cutaneous lesions in conventionally resistant C57BL/6 mice was more efficiently taken up by M2-polarized bone marrow (BM)-derived macrophages (BMDMs) in vitro and by mannose receptor (MR)
dermal macrophages in vivo compared with a healing strain (
Friedlin V1). Both in steady and in T helper type 1 (Th1) cell-driven inflammatory states, the MR
dermal macrophages showed M2 characteristics. The dermal macrophages were radio resistant and not replaced by monocytes or adult BM-derived cells during infection, but were locally maintained by IL-4 and IL-10. Notably, the favored infection of M2 BMDMs by LmSd in vitro was MR dependent, and genetic deletion of MR or selective depletion of MR
dermal macrophages by anti-CSF-1 receptor antibody reversed the nonhealing phenotype. We conclude that embryonic-derived, MR
dermal macrophages are permissive for parasite growth even in a strong Th1-immune environment, and the preferential infection of these cells plays a crucial role in the severity of cutaneous disease.
Leishmaniasis is a neglected tropical disease affecting millions of individuals worldwide. P2X7 receptor has been linked to the elimination of Leishmania amazonensis. Biological responses evoked by ...P2X7 receptor activation have been well-documented, including apoptosis, phagocytosis, cytokine release, such as IL-1β. It was demonstrated that NLRP3 inflammasome activation and IL-1β signaling participated in resistance against L. amazonensis. Furthermore, our group has shown that L. amazonensis elimination through P2X7 receptor activation depended on leukotriene B4 (LTB4) production and release. Therefore, we investigated whether L. amazonensis elimination by P2X7 receptor and LTB4 involved NLRP3 inflammasome activation and IL-1β signaling. We showed that macrophages from NLRP3-/-, ASC-/-, Casp-1/11-/-, gp91phox-/- , and IL-1R-/- mice treated with ATP or LTB4 did not decrease parasitic load as was observed in WT mice. When ASC-/- macrophages were treated with exogenous IL-1β, parasite killing was noted, however, we did not see parasitic load reduction in IL-1R-/- macrophages. Similarly, macrophages from P2X7 receptor-deficient mice treated with IL-1β also showed decreased parasitic load. In addition, when we infected Casp-11-/- macrophages, neither ATP nor LTB4 were able to reduce parasitic load, and Casp-11-/- mice were more susceptible to L. amazonensis infection than were WT mice. Furthermore, P2X7-/- L. amazonensis-infected mice locally treated with exogenous LTB4 showed resistance to infection, characterized by lower parasite load and smaller lesions compared to untreated P2X7-/- mice. A similar observation was noted when infected P2X7-/- mice were treated with IL-1β, i.e., lower parasite load and smaller lesions compared to P2X7-/- mice. These data suggested that L. amazonensis elimination mediated by P2X7 receptor and LTB4 was dependent on non-canonical NLRP3 inflammasome activation, ROS production, and IL-1β signaling.
This study aimed to identify potential inhibitors and investigate the mechanism of action on SARS-CoV-2 ACE2 receptors using a molecular modeling study and theoretical determination of biological ...activity. Hydroxychloroquine was used as a pivot structure and antimalarial analogues of 1,2,4,5 tetraoxanes were used for the construction and evaluation of pharmacophoric models. The pharmacophore-based virtual screening was performed on the Molport
database (~7.9 million compounds) and obtained 313 structures. Additionally, a pharmacokinetic study was developed, obtaining 174 structures with 99% confidence for human intestinal absorption and penetration into the blood-brain barrier (BBB); posteriorly, a study of toxicological properties was realized. Toxicological predictions showed that the selected molecules do not present a risk of hepatotoxicity, carcinogenicity, mutagenicity, and skin irritation. Only 54 structures were selected for molecular docking studies, and five structures showed binding affinity (ΔG) values satisfactory for ACE2 receptors (PDB 6M0J), in which the molecule MolPort-007-913-111 had the best ΔG value of -8.540 Kcal/mol, followed by MolPort-002-693-933 with ΔG = -8.440 Kcal/mol. Theoretical determination of biological activity was realized for 54 structures, and five molecules showed potential protease inhibitors. Additionally, we investigated the Mpro receptor (6M0K) for the five structures via molecular docking, and we confirmed the possible interaction with the target. In parallel, we selected the TopsHits 9 with antiviral potential that evaluated synthetic accessibility for future synthesis studies and in vivo and in vitro tests.
Leishmania major is the main causative agent of cutaneous leishmaniasis in the Old World. In Leishmania parasites, the lack of transcriptional control is mostly compensated by post-transcriptional ...mechanisms. Methylation of arginine is a conserved post-translational modification executed by Protein Arginine Methyltransferase (PRMTs). The genome from L. major encodes five PRMT homologs, including the cytosolic protein associated with several RNA-binding proteins, LmjPRMT7. It has been previously reported that LmjPRMT7 could impact parasite infectivity. In addition, a more recent work has clearly shown the importance of LmjPRMT7 in RNA-binding capacity and protein stability of methylation targets, demonstrating the role of this enzyme as an important epigenetic regulator of mRNA metabolism. In this study, we unveil the impact of PRMT7-mediated methylation on parasite development and virulence. Our data reveals that higher levels of LmjPRMT7 can impair parasite pathogenicity, and that deletion of this enzyme rescues the pathogenic phenotype of an attenuated strain of L. major. Interestingly, lesion formation caused by LmjPRMT7 knockout parasites is associated with an exacerbated inflammatory reaction in the tissue correlated with an excessive neutrophil recruitment. Moreover, the absence of LmjPRMT7 also impairs parasite development within the sand fly vector Phlebotomus duboscqi. Finally, a transcriptome analysis shed light onto possible genes affected by depletion of this enzyme. Taken together, this study highlights how post-transcriptional regulation can affect different aspects of the parasite biology.
Pentacyclic triterpenes in general exert beneficial effects in metabolic disorders. This study investigated the effects of α, β-amyrin, a pentacyclic triterpene mixture from the resin of Protium ...heptaphyllum on blood sugar level and lipid profile in normal and streptozotocin (STZ)-induced diabetic mice, and in mice fed on a high-fat diet (HFD).
Mice treated with α, β-amyrin (10, 30 and 100 mg/kg, p.o.) or glibenclamide (10 mg/kg, p.o.) had significantly reduced STZ-induced increases in blood glucose (BG), total cholesterol (TC) and serum triglycerides (TGs). Unlike glibenclamide that showed significant reductions in BG, TC and TGs in normoglycemic mice, α, β-amyrin did not lower normal blood sugar levels but at 100 mg/kg, manifested a hypolipidemic effect. Also, α, β-amyrin effectively reduced the elevated plasma glucose levels during the oral glucose tolerance test. Moreover, the plasma insulin level and histopathological analysis of pancreas revealed the beneficial effect of α, β-amyrin in the preservation of beta cell integrity. In mice treated orally with α, β-amyrin (10, 30 and 100 mg/kg) or fenofibrate (200 mg/kg), the HFD-associated rise in serum TC and TGs were significantly less. The hypocholesterolemic effect of α, β-amyrin appeared more prominent at 100 mg/kg with significant decreases in VLDL and LDL cholesterol and an elevation of HDL cholesterol. Besides, the atherogenic index was significantly reduced by α, β-amyrin.
These findings reflect the potential antihyperglycemic and hypolipidemic effects of α, β-amyrin mixture and suggest that it could be a lead compound for drug development effective in diabetes and atherosclerosis.
Leishmaniasis is a neglected tropical disease that causes several clinical manifestations. Parasites of the genus Leishmania cause this disease. Spread across five continents, leishmaniasis is a ...particular public health problem in developing countries. Leishmania infects phagocytic cells such as macrophages, where it induces adenosine triphosphate (ATP) release at the time of infection. ATP activates purinergic receptors in the cell membranes of infected cells and promotes parasite control by inducing leukotriene B4 release and NLRP3 inflammasome activation. Moreover, uridine triphosphate induces ATP release, exacerbating the immune response. However, ATP may also undergo catalysis by ectonucleotidases present in the parasite membrane, generating adenosine, which activates P1 receptors and induces the production of anti-inflammatory molecules such as prostaglandin E2 and IL-10. These mechanisms culminate in Leishmania's survival. Thus, how Leishmania handles extracellular nucleotides and the activation of purinergic receptors determines the control or the dissemination of the disease.
Learning Objectives
After completing this course, the reader will be able to:
Explain how malnutrition (deficit or excess) is used as a decisive factor in treatment of cancer patients.
Describe the ...interactions and influences of overweight/obesity on tumor metabolism and of individualized tumor metabolism on tumor burden and undernutrition.
Use the association of sarcopenic obesity to predict and manage poorer performance status and decreased survival in cancer patients.
This article is available for continuing medical education credit at CME.TheOncologist.com
Objective.
Nutritional status in cancer has been mostly biased toward undernutrition, an issue now in dispute. We aimed to characterize nutrition status, to analyze associations between nutritional and clinical/cancer‐related variables, and to quantify the relative weights of nutritional and cancer‐related features.
Methods.
The cross‐sectional study included 450 nonselected cancer patients (ages 18–95 years) at referral for radiotherapy. Nutritional status assessment included recent weight changes, body mass index (BMI) categorized by World Health Organization's age/sex criteria, and Patient‐Generated Subjective Global Assessment (PG‐SGA; validated/specific for oncology).
Results.
BMI identified 63% as ≥25 kg/m2 (43% overweight, 20% obese) and 4% as undernourished. PG‐SGA identified 29% as undernourished and 71% as well nourished. Crossing both methods, among the 319 (71%) well‐nourished patients according to PG‐SGA, 75% were overweight/obese and only 25% were well nourished according to BMI. Concordance between BMI and PG‐SGA was evaluated and consistency was confirmed. More aggressive/advanced stage cancers were more prevalent in deficient and excessive nutritional status: in 83% (n = 235/282) of overweight/obese patients by BMI and in 85% (n = 111/131) of undernourished patients by PG‐SGA. Results required adjustment for diagnoses: greater histological aggressiveness was found in overweight/obese prostate and breast cancer; undernutrition was associated with aggressive lung, colorectal, head‐neck, stomach, and esophageal cancers (p < .005). Estimates of effect size revealed that overweight/obesity was associated with advanced stage (24%), aggressive breast (10%), and prostate (9%) cancers, whereas undernutrition was associated with more aggressive lung (6%), colorectal (6%), and head‐neck (6%) cancers; in both instances, age and longer disease duration were of significance.
Conclusion.
Undernutrition and overweight/obesity have distinct implications and bear a negative prognosis in cancer. This study provides novel data on the prevalence of overweight/obesity and undernutrition in cancer patients and their potential role in cancer histological behavior.
This paper provides novel data on the prevalence of overweight/obesity and undernutrition in cancer patients and shows that there is a likely relation among nutritional status, disease aggressiveness, and consequent association with prognosis.
This study investigated the potential of selected compounds as inhibitors of SARS-CoV-2 Mpro through pharmacokinetic and toxicological analyses, molecular docking, and molecular dynamics simulations. ...In silico molecular docking simulations revealed promising ligands with favorable binding affinities for Mpro, ranging from −6.2 to −9.5 kcal/mol. Moreover, molecular dynamics simulations demonstrated the stability of protein–ligand complexes over 200 ns, maintaining protein secondary structures. MM-PBSA analysis revealed favorable interactions between ligands and Mpro, with negative binding energy values. Hydrogen bond formation capacity during molecular dynamics was confirmed, indicating consistent interactions with Mpro catalytic residues. Based on these findings, selected ligands show promise for future studies in developing COVID-19 treatments.
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