Biology subjects

Ashkar, A. A.

Publications and source records attributed to Ashkar, A. A..

4 recordsLinked to original sources

bioRxiv2025

Single-Cell Analysis of NK Cell Cytotoxicity in Cancer Therapy Using Microfluidic Droplets

Natural Killer (NK) cells are critical components of the immune system, uniquely capable of detecting and eliminating cancer cells without prior sensitization. Here, a droplet-based microfluidic platform is introduced that enables real-time monitoring and single-cell analysis of NK cell-mediated cytotoxicity against K562 cancer cells. Distinct NK cells are evaluated to quantify key metrics, including the percentage of cytotoxic NK cells, serial killing capacity, killing time per target, NK-target contact duration, and migration velocities. The results demonstrated that expanded NK cells (exNK) exhibited longer attachments, superior cytotoxic activity, serial killing, and rapid killing dynamics, whereas peripheral blood NK cells (pbNK), especially when they were exposed to ascites tumor microenvironment (TME) (pbNK-asc), displayed reduced cytotoxic abilities in all parameters. Interestingly, expanded NK cells exposed to ascites TME (exNK-asc) retained partial functionality, indicating that expansion provides resilience against suppressive factors. In addition, cell velocity analysis further revealed that the presence of a cancer cell increases the migration of NK cells. This single-cell analysis provides novel insights into NK-cancer cell interactions, offering a robust framework for enhancing the efficacy of future immunotherapy applications especially for optimizing off-the-shelf NK cell-based immunotherapies. Table of Contents O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=151 SRC="FIGDIR/small/651923v1_ufig1.gif" ALT="Figure 1"> View larger version (65K): org.highwire.dtl.DTLVardef@1f6e0b0org.highwire.dtl.DTLVardef@11971fborg.highwire.dtl.DTLVardef@18a2cdeorg.highwire.dtl.DTLVardef@87d4d9_HPS_FORMAT_FIGEXP M_FIG A droplet-based microfluidic platform examines how Natural Killer (NK) cells target cancer cells at the single-cell level. By comparing peripheral blood and expanded NK cells under normal and tumor-like conditions, distinct differences in attachment, serial killing, killing time, and migration are revealed. These findings provide insights that could enhance tumor targeting, particularly in off-the-shelf NK cell therapies. C_FIG

immunology↗

bioRxiv2024

Maternal obesogenic diet disrupts mid-gestation decidual immune and vascular homeostasis without impairing spiral artery remodelling

Excess maternal adiposity (i.e., overweight and obesity) during pregnancy has been linked to impaired uteroplacental perfusion, compromised placental development, and a higher risk of adverse pregnancy outcomes. Owing to the nature of chronic inflammation and immune dysregulation accompanying excess adiposity, disruption of leukocyte-mediated tissue remodelling and immunoregulation within the decidua have emerged as likely drivers contributing to suboptimal placental function in pregnancies impacted by maternal overweight or obesity. However, the impacts of excess adiposity on major populations of innate lymphoid cells (ILCs) and macrophages which orchestrate these processes and the environment that these cells occupy remain vastly understudied. Here, we used a mouse model of chronic high-fat, high-sucrose (HFHS) diet-feeding to characterize the impacts of an obesogenic milieu on decidual immune dynamics during placental development at mid-gestation (E10.5). HFHS pregnancies exhibited marked increases in total decidual leukocyte abundance, driven by population-level increases in tissue-resident and conventional NK cells, and MHC-II+ macrophages. This was not associated with abnormalities in implantation site morphology or decidual spiral artery remodelling but was coincident with histological patterns of local inflammation. In line with this, expression of canonical proinflammatory cytokines and chemokines were moderately upregulated in bulk decidual tissue of HFHS dams. This was accompanied by more potent elevations in multiple mediators of angiogenesis, endothelial activation, and coagulation in HFHS decidual tissue. Collectively, these findings point towards pathological vascular inflammation and possibly dysregulated decidual angiogenesis in the first half of pregnancy as factors predisposing to reduced placental efficiency, malperfusion, and inflammation seen in pregnancies affected by maternal overweight and obesity.

developmental biology↗

bioRxiv2023

Targeting the MR1-MAIT Cell Axis Improves Vaccine Efficacy and Affords Protection against Viral Pathogens

Mucosa-associated invariant T (MAIT) cells are MR1-restricted, innate-like T lymphocytes with tremendous antibacterial and immunomodulatory functions. MAIT cells also sense and respond to viral infections in an MR1-independent fashion. However, whether they can be directly targeted in immunization strategies against viral pathogens is unknown. We addressed this question in multiple wild-type and genetically altered but clinically relevant mouse strains using several vaccine platforms against influenza viruses, poxviruses and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We demonstrate that 5-(2-oxopropylideneamino)-6-D-ribitylaminouracil (5-OP-RU), a riboflavin-based MR1 ligand of bacterial origin, can synergize with viral vaccines to expand MAIT cells in multiple tissues, reprogram them towards a pro-inflammatory MAIT1 phenotype, license them to bolster mainstream virus-specific CD8+ T cell responses, and potentiate heterosubtypic antiviral protection. Repeated 5-OP-RU administration did not render MAIT cells anergic, thus allowing for its inclusion in prime-boost immunization protocols. Mechanistically, tissue MAIT cell accumulation was due to their robust proliferation, as opposed to altered migratory behavior, and required viral vaccine replication competency, Toll-like receptor 3 (TLR3) and cell-autonomous type I interferon receptor signaling. Furthermore, the observed phenomenon was manifest in young and old female and male mice, and could also be recapitulated in a human cell culture system in which peripheral blood mononuclear cells were exposed to replicating virions and 5-OP-RU. In conclusion, although viruses and virus-based vaccines are devoid of the riboflavin biosynthesis machinery that supplies MR1 ligands, targeting MR1 enhances the efficacy of vaccine-elicited antiviral immunity. We propose 5-OP-RU as a non-classic but potent and versatile vaccine adjuvant against respiratory viruses.

immunology↗

bioRxiv2018

Medroxyprogesterone acetate mediated alteration in the vaginal microbiota and microenvironment in a Kenyan sex worker cohort

AbstractThe hormonal contraceptive Medroxyprogesterone Acetate (MPA) is associated with increased risk of Human Immunodeficiency Virus (HIV), via incompletely understood mechanisms. Increased diversity in the vaginal microbiota modulates genital inflammation and is associated with increased HIV-1 acquisition. However, the effect of MPA on diversity of the vaginal microbiota is relatively unknown. In a cohort of female Kenyan sex workers, negative for sexually transmitted infections (STIs), with Nugent Scores <7 (N=58 of 370 screened), MPA correlated with significantly increased diversity of the vaginal microbiota as assessed by 16S rRNA gene sequencing. MPA was also significantly associated with low vaginal glycogen and -amylase, factors implicated in vaginal colonization by lactobacilli, bacteria believed to protect against STIs. Furthermore, increased diversity of the vaginal microbiota correlated with activation of vaginal HIV-1 target cells. Results were recapitulated in humanized mice where MPA treatment was associated with increased diversity of the vaginal microbiota, low glycogen, and enhanced HIV-1 susceptibility. Together these results suggest MPA-induced hypo-estrogenism may alter key metabolic components necessary for vaginal colonization by certain bacterial species including lactobacilli, and allow for greater bacterial diversity in the vaginal microbiota. Bacterial diversity in the vaginal microbiota correlates with activation of HIV-1 target cells, which might thus contribute to enhanced susceptibility to HIV-1.

molecular biology↗