HIV infection significantly affects the frequencies and functions of immunoregulatory CD3+CD4-CD8- double-negative (DN) T-cells, while the effect of early antiretroviral therapy (ART) initiation on these cells remains understudied. DN T-cell subsets were analyzed prospectively in 10 HIV+ individuals during acute infection and following early ART initiation compared to 20 HIV-uninfected controls. In this study, 21 Rhesus macaques (RMs) were SIV-infected, of which 13 were assessed during acute infection and 8 following ART initiation four days post-infection. DN T-cells and FoxP3+ DN Treg frequencies increased during acute HIV infection, which was not restored by ART. The expression of activation (HLA-DR/CD38), immune checkpoints (PD-1/CTLA-4), and senescence (CD28-CD57+) markers by DN T-cells and DN Tregs increased during acute infection and was not normalized by ART. In SIV-infected RMs, DN T-cells remained unchanged despite infection or ART, whereas DN Treg frequencies increased during acute SIV infection and were not restored by ART. Finally, frequencies of CD39+ DN Tregs increased during acute HIV and SIV infections and remained elevated despite ART. Altogether, acute HIV/SIV infections significantly changed DN T-cell and DN Treg frequencies and altered their immune phenotype, while these changes were not fully normalized by early ART, suggesting persistent HIV/SIV-induced immune dysregulation despite early ART initiation.

The bone marrow microenvironment (BME) drives drug resistance in acute lymphoblastic leukemia (ALL) through leukemic cell interactions with bone marrow (BM) niches, but the underlying mechanisms remain unclear. Here, we show that the interaction between ALL and mesenchymal stem cells (MSCs) through integrin β1 induces an epithelial-mesenchymal transition (EMT)-like program in MSC-adherent ALL cells, resulting in drug resistance and enhanced survival. Moreover, single-cell RNA sequencing analysis of ALL-MSC co-culture identifies a hybrid cluster of MSC-adherent ALL cells expressing both B-ALL and MSC signature genes, orchestrated by a WNT/β-catenin-mediated EMT-like program. Blockade of interaction between β-catenin and CREB binding protein impairs the survival and drug resistance of MSC-adherent ALL cells in vitro and results in a reduction in leukemic burden in vivo. Targeting of this WNT/β-catenin-mediated EMT-like program is a potential therapeutic approach to overcome cell extrinsically acquired drug resistance in ALL.
Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.

Previous studies reported on the safety and applicability of mesenchymal stem/stromal cells (MSCs) to ameliorate pulmonary inflammation in acute respiratory distress syndrome (ARDS). Thus, multiple clinical trials assessing the potential of MSCs for COVID-19 treatment are underway. Yet, as SARS-inducing coronaviruses infect stem/progenitor cells, it is unclear whether MSCs could be infected by SARS-CoV-2 upon transplantation to COVID-19 patients. We found that MSCs from bone marrow, amniotic fluid, and adipose tissue carry angiotensin-converting enzyme 2 and transmembrane protease serine subtype 2 at low levels on the cell surface under steady-state and inflammatory conditions. We did not observe SARS-CoV-2 infection or replication in MSCs at steady state under inflammatory conditions, or in direct contact with SARS-CoV-2-infected Caco-2 cells. Further, indoleamine 2,3-dioxygenase 1 production in MSCs was not impaired in the presence of SARS-CoV-2. We show that MSCs are resistant to SARS-CoV-2 infection and retain their immunomodulation potential, supporting their potential applicability for COVID-19 treatment.
Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.

Vascular calcification is a severe pathological event in the manifestation of atherosclerosis. Pathogenic triggers mediating osteogenic differentiation of arterial smooth muscle cells (SMC) in humans remain insufficiently understood and are to a large extent investigated in animal models or cells derived thereof. Here, we describe an in vitro model based on SMC derived from healthy and diseased humans that allows to comprehensively investigate vascular calcification mechanisms. Comparing the impact of the commonly used SMC culture media VascuLife, DMEM, and M199, cells were characterised by immunofluorescence, flow cytometry, qPCR, and regarding their contractility and proliferative capacity. Irrespective of the arterial origin, the clinical background and the expansion medium used, all cells expressed typical molecular SMC marker while contractility varied between donors. Interestingly, the ability to induce an osteogenic differentiation strongly depended on the culture medium, with only SMC cultured in DMEM depositing calcified matrix upon osteogenic stimulation, which correlated with increased alkaline phosphatase activity, increased inorganic phosphate level and upregulation of osteogenic gene markers. Our optimized model is suitable for donor-oriented as well as broader screening of potential pathogenic mediators triggering vascular calcification. Translational studies aiming to identify and to evaluate therapeutic targets in a personalized fashion would be feasible.