Molecular diagnosis of trypanosomatids in Didelphis marsupialis from Los Montes de María: a first report of Trypanosoma rangeli from Colombian Caribbean region.

Didelphis marsupialis is a primary reservoir of Trypanosoma cruzi, etiologic agent of American Trypanosomiasis-AT or Chagas Disease-CD, in America. Some findings of Trypanosoma rangeli have been recorded in this mammal, in sympatry with T. cruzi. In Los Montes de María, Bolívar, Colombian Caribbean, triatomine insects and potential parasite host has been registered, but little is known about the relationship between these parasites and D. marsupialis. We investigated the natural trypanosomatids infection rate in D. marsupialis, applying a parasitological and molecular diagnosis. Twenty D. marsupialis was investigated between 2018 and 2019 using 21 Tomahawk® traps placed on the sylvatic/domestic corridors. Blood was drawn by cardiopuncture after sedation. An aliquot of blood samples was cultured in Novy, Nicolle, McNeal/Roswell Park Memorial Institute medium at 24 °C/60 days for the detection of motile trypomastigotes. Parasite DNA was obtained by salting out methods from positive blood cultures. Trypanosomatids diagnosis was done by Polymerase Chain Reaction-sequencing of V7V8 region of 18S ribosomal RNA (18S-rRNA) gene. Amplicons were sequenced, and consensus sequences were aligned with reference sequences from GenBank. Four isolates corresponded to T. rangeli (20%) and one to T. cruzi (5%). The natural infection of D. marsupialis by T. rangeli and T. cruzi constitutes the first record of these parasites in didelphids in Los Montes de María and the first record of T. rangeli in this marsupial, in the Colombian Caribbean.

Kinetic Characterization of ASXL1/2-Mediated Allosteric Regulation of the BAP1 Deubiquitinase.

BAP1 is an ubiquitin hydrolase whose deubiquitinase activity is mediated by polycomb group-like protein ASXL2. Cancer-related BAP1 mutations/deletions lead to loss-of-function by targeting the catalytic ubiquitin C-terminal hydrolase (UCH) or UCH37-like domain (ULD) domains of BAP1, and the latter disrupts binding to ASXL2, an obligate partner for BAP1 enzymatic activity. However, the biochemical and biophysical properties of domains involved in forming the enzymatically active complex are unknown. Here, we report the molecular dynamics, kinetics, and stoichiometry of these interactions. We demonstrate that interactions between BAP1 and ASXL2 are direct, specific, and stable to biochemical and biophysical manipulations as detected by isothermal titration calorimetry (ITC), GST association, and optical biosensor assays. Association of the ASXL2-AB box greatly stimulates BAP1 activity. A stable ternary complex is formed, comprised of the BAP1-UCH, BAP1-ULD, and ASXL2-AB domains. Stoichiometric analysis revealed that one molecule of the ULD domain directly interacts with one molecule of the AB box. Real-time kinetic analysis of the ULD/AB protein complex to the BAP1-UCH domain, based on surface plasmon resonance, indicated that formation of the ULD/AB complex with the UCH domain is a single-step event with fast association and slow dissociation rates. In vitro experiments validated in cells that the ASXL-AB box directly regulates BAP1 activity. IMPLICATIONS: Collectively, these data elucidate molecular interactions between specific protein domains regulating BAP1 deubiquitinase activity, thus establishing a foundation for small-molecule approaches to reactivate latent wild-type BAP1 catalytic activity in BAP1-mutant cancers.

Detecting Prostate Cancer Using Pattern Recognition Neural Networks With Flow Cytometry-Based Immunophenotyping in At-Risk Men.

Current screening methods for prostate cancer (PCa) result in a large number of false positives making it difficult for clinicians to assess disease status, thus warranting advancements in screening and early detection methods. The goal of this study was to design a liquid biopsy test that uses flow cytometry-based immunophenotyping and artificial neural network (ANN) analysis to detect PCa. Numerous myeloid and lymphoid cell populations, including myeloid-derived suppressor cells, were measured from 156 patients with PCa, 123 with benign prostatic hyperplasia (BPH), and 99 male healthy donor (HD) controls. Using pattern recognition neural network (PRNN) analysis, a type of ANN, PCa detection compared against HD resulted in 96.6% sensitivity, 87.5% specificity, and an area under the curve (AUC) value of 0.97. Detecting patients with higher risk disease (⩾Gleason 7) against lower risk disease (BPH/Gleason 6) resulted in 92.0% sensitivity, 42.7% specificity, and an AUC of 0.72. This study suggests that analyzing flow cytometry immunophenotyping data with PRNNs may prove to be a useful tool to improve PCa detection and reduce the number of unnecessary prostate biopsies performed each year.

Identification of monocyte-like precursors of granulocytes in cancer as a mechanism for accumulation of PMN-MDSCs.

We have identified a precursor that differentiates into granulocytes in vitro and in vivo yet belongs to the monocytic lineage. We have termed these cells monocyte-like precursors of granulocytes (MLPGs). Under steady state conditions, MLPGs were absent in the spleen and barely detectable in the bone marrow (BM). In contrast, these cells significantly expanded in tumor-bearing mice and differentiated to polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs). Selective depletion of monocytic cells had no effect on the number of granulocytes in naive mice but decreased the population of PMN-MDSCs in tumor-bearing mice by 50%. The expansion of MLPGs was found to be controlled by the down-regulation of Rb1, but not IRF8, which is known to regulate the expansion of PMN-MDSCs from classic granulocyte precursors. In cancer patients, putative MLPGs were found within the population of CXCR1+CD15-CD14+HLA-DR-/lo monocytic cells. These findings describe a mechanism of abnormal myelopoiesis in cancer and suggest potential new approaches for selective targeting of MDSCs.