Biology subjects

Loiselle, A.

Publications and source records attributed to Loiselle, A..

11 recordsLinked to original sources

bioRxiv2025

Cryptic leukemia antigens share homology with microbial epitopes and stimulate T-cell responses in healthy donors

Leukemia cells express cryptic tumor-specific antigens (TSAs) derived from aberrantly transcribed non-exomic genome sequences. These antigens are generally absent from healthy tissues yet shared across patients, making them attractive immunotherapy targets by minimizing on-target/off-tumor toxicity while offering broad applicability. However, their immunogenic potential and the nature of the T-cell repertoire they stimulate remain unknown. Cryptic antigen-specific CD8+ T cells could be expanded from healthy donor T-cell repertoires for six out of nine candidate acute leukemia cryptic TSA. T-cell receptor (TCR) and epitope sequence analysis revealed oligoclonal or near-monoclonal responses, involving shared and donor-restricted clonotypes recognizing cryptic TSAs which shared sequence homology with microbial epitopes. Orthotopic TCR replacement with cryptic TSA-specific TCR chains using a one-step CRISPR-Cas9 approach further validated the antigenic specificity and therapeutic potential of two TCRs respectively targeting cryptic TSAs from acute myeloid and lymphoid leukemia. To our knowledge, this is the first report describing functional TCRs directed against cryptic leukemia TSAs and highlights their potential as a new class of antigens for T-cell-based immunotherapies. Key pointsO_LIA high proportion of cryptic leukemia TSAs shares homology with microbial epitopes and can stimulate expansion of low-frequency T cell repertoire in healthy individuals. C_LIO_LIEx vivo expansion of cryptic TSA-specific T cells enables TCR identification that can be used to devise new T cell immunotherapies. C_LI Visual Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=122 SRC="FIGDIR/small/691479v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@1bd720dorg.highwire.dtl.DTLVardef@8ac6d6org.highwire.dtl.DTLVardef@104289aorg.highwire.dtl.DTLVardef@5a65e_HPS_FORMAT_FIGEXP M_FIG C_FIG ConclusionCryptic leukemia antigens elicit antigenic and specific T-cell responses and represents novel targets for TCR or BiTE immunotherapy.

immunology↗

bioRxiv2023

Higher Angiotensin I Converting Enzyme 2 (ACE2) levels in the brain of individuals with Alzheimer's disease.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a major cause of death in the elderly. Cognitive decline due to Alzheimers disease (AD) is frequent in the geriatric population disproportionately affected by the COVID-19 pandemic. Interestingly, central nervous system (CNS) manifestations have been reported in SARS-CoV-2-infected patients. In this study, we investigated the levels of Angiotensin I Converting Enzyme 2 (ACE2), the main entry receptor of SARS-COV-2 in cells, in postmortem parietal cortex samples from two independent AD cohorts, totalling 142 persons. Higher concentrations of ACE2 protein and mRNA were found in individuals with a neuropathological diagnosis of AD compared to age-matched healthy control subjects. Brain levels of soluble ACE2 were inversely associated with cognitive scores (p = 0.02), markers of pericytes (PDGFR{beta}, p=0.02 and ANPEP, p = 0.007) and caveolin1 (p = 0.03), but positively correlated with soluble amyloid-{beta} peptides (A{beta}) concentrations (p = 0.01) and insoluble phospho- tau (S396/404, p = 0.002). No significant differences in ACE2 were observed in the 3xTgAD mouse model of tau and A{beta} neuropathology. Results from immunofluorescence and Western blots showed that ACE2 protein is mainly localized in neurons in the human brain but predominantly in microvessels in the mouse brain. The present data show that an AD diagnosis is associated with higher levels of soluble ACE2 in the human brain, which might contribute to a higher risk of CNS SARS-CoV-2 infection.

neuroscience↗

bioRxiv2022

Widespread alterations in microRNA biogenesis in human Huntington's disease putamen

Altered microRNA (miRNA) expression is a common feature of Huntingtons disease (HD) and could participate in disease onset and progression. However, little is known about the underlying causes of miRNA disruption in HD. We and others have previously shown that mutant Huntingtin (mHTT) binds to Ago2, a central component of miRNA biogenesis, and disrupts mature miRNA levels. In this study, we sought to determine if miRNA maturation per se was compromised in HD. Towards this end, we characterized t major miRNA biogenesis pathway components and miRNA maturation products (pri-miRNA, pre-miRNA, and mature) in human HD (N=41, Vonsattel grades HD2-4) and healthy control (N=25) subjects. Notably, the striatum (putamen) and cortex (BA39) from the same individuals were analyzed in parallel. We show that Ago2, Drosha, and Dicer were strongly downregulated in human HD at early stages of disease. Using a panel of HD-related miRNAs (miR-10b, miR-196b, miR-132, miR-212, miR-127, miR-128), we uncovered various types of maturation defects in HD brain, the most prominent occurring at the pre-miRNA to mature miRNA maturation step. Consistent with earlier findings, we provide evidence that alterations in autophagy could participate in miRNA maturation defects. Notably, most changes occurred in the striatum, which is more prone to HTT aggregation and neurodegeneration. Likewise, we observed no significant alterations in miRNA biogenesis in human HD cortex and blood, strengthening tissue-specific effects. Overall, these data provide important clues into the underlying mechanisms behind miRNA alterations in HD-susceptible tissues. Further investigations are now required to understand the biological, diagnostic, and therapeutic implications of miRNA/RNAi biogenesis defects in HD and related neurodegenerative disorders.

neuroscience↗

bioRxiv2021

Marker-free coselection for successive rounds of prime editing in human cells

Prime editing enables the introduction of precise point mutations, small insertions, or short deletions without requiring donor DNA templates. However, efficiency remains a key challenge in a broad range of human cell types. In this work, we designed a robust coselection strategy through coediting of the ubiquitous and essential sodium/potassium pump (Na+/K+ ATPase). We readily engineered highly modified pools of cells and clones with homozygous modifications for functional studies with minimal pegRNA optimization. This process revealed that nicking the non-edited strand stimulates multiallelic editing but often generates tandem duplications and large deletions at the target site, an outcome dictated by the relative orientation of the protospacer adjacent motifs. Our approach streamlines the production of cell lines with multiple genetic modifications to create cellular models for biological research and lays the foundation for the development of cell-type specific coselection strategies.

molecular biology↗

bioRxiv2019

Cell non-autonomous functions of S100a4 drive fibrotic tendon healing

Identification of pro-regenerative approaches to improve tendon healing is of critical importance given the diminished quality of life and physical function that accompanies the typical fibrotic response to tendon injury. S100a4 modulates fibrosis through tissue-type dependent mechanisms, and the role of S100a4 in fibrotic, scar-mediated tendon healing has not been established. In the present study we tested the hypothesis that inhibition of S100a4 improves tendon function following acute injury and surgical repair. We demonstrate cell non-autonomous functions of S100a4 as S100a4 haploinsufficiency promotes regenerative tendon healing, including decreased scar formation and improved mechanical properties. Moreover, inhibition of S100a4 via antagonism of its putative receptor, the Receptor for Advanced Glycation Endproducts (RAGE), also decreases scar formation. Mechanistically, knock-down of S100a4 decreases myofibroblast and macrophage content at the site of injury, with both cell populations being key drivers of fibrotic progression. In contrast, S100a4+ cell depletion displays time-dependent effects on scar formation, and consistent impairments in restoration of mechanical properties, indicating a critical role for these cells in re-establishing tendon strength after injury. Finally, we demonstrate, that S100a4-lineage cells become -SMA+ myofibroblasts, via loss of S100a4 expression. Using a combination of genetic mouse models, small molecule inhibitors and in vitro studies we have defined S100a4 as a novel, promising therapeutic candidate to improve tendon function after acute injury.

cell biology↗

bioRxiv2018

Scleraxis Lineage Cells Contribute to Organized Bridging Tissue During Tendon Healing, and Identifies Subpopulations of Resident Tendon Cells

During tendon healing, it is postulated that intrinsic tendon cells drive tissue regeneration while extrinsic cells drive pathological scar formation. Intrinsic tendon cells are frequently described as a homogenous, fibroblast population that is positive for the marker Scleraxis. It is controversial whether intrinsic Scleraxis localize within the forming scar tissue during adult tendon healing. We have previously demonstrated that calcium binding protein S100a4 is a driver of tendon scar formation and marks a subset of intrinsic tendon cells. However, the relationship between Scleraxis and S100a4 has not been explored. In this study, we aimed to investigate the localization of Scleraxis lineage cells following adult murine flexor tendon repair and to establish the relationship between Scleraxis and S100a4 throughout both homeostasis and healing. We have shown that adult Scleraxis lineage cells localize within the scar tissue and organize into a highly aligned cellular bridge during tendon healing. Additionally, we demonstrate that markers Scleraxis and S100a4 label distinct populations in tendon during homeostasis and localize differently within tendon scar tissue, with Scleraxis found specifically in the organized bridging tissue and S100a4 localized throughout the entire scar region. These studies define a heterogeneous tendon cell environment and demonstrate discreet contributions of subpopulations during healing. Taken together, these data enhance our understanding and ability to target the complex cellular environment of the tendon during homeostasis and healing.

cell biology↗

bioRxiv2018

Non-invasive ultrasound quantification of Scar Tissue Volume predicts functional changes during tendon healing

Tendon injuries are very common and disrupt the transmission of forces from muscle to bone, leading to impaired function and quality of life. Successful restoration of tendon function after injury is a challenging clinical problem due to the pathological, scar-mediated manner in which tendons heal. Currently, there are no standard treatments to modulate scar tissue formation and improve tendon healing. A major limitation to the identification of therapeutic candidates has been the reliance on terminal end-point metrics of healing in pre-clinical studies, which require a large number of animals and result in destruction of the tissue. To address this limitation, we have identified quantification of Scar Tissue Volume (STV) from ultrasound imaging as a longitudinal, non-invasive metric of tendon healing. STV was strongly correlated with established endpoint metrics of gliding function including Gliding Resistance (GR) and Metatarsophalangeal (MTP) Flexion Angle. However, no associations were observed between STV and tensile mechanical properties. To define the sensitivity of STV to identify differences between functionally discrete tendon healing phenotypes, we utilized S100a4 haploinsufficient mice (S100a4GFP/+), which heal with improved gliding function relative to wildtype (WT) littermates. A significant decrease in STV was observed in S100a4GFP/+repairs, relative to WT at day 14. Taken together, these data suggest US quantification of STV as a means to facilitate the rapid screening of biological and pharmacological interventions to improve tendon healing, and identify promising therapeutic targets, in an efficient, cost-effective manner.

bioengineering↗

bioRxiv2018

Insulin Receptor Deletion in S100a4-lineage cells accelerates age-related bone loss

Type I and Type II Diabetes dramatically impair skeletal health. Altered Insulin Receptor (IR) signaling is a common feature of both diseases, and insulin has potent bone anabolic functions. Several previous studies have demonstrated that loss of IR in bone cells results in disrupted bone homeostasis during early post-natal growth. Here we have deleted IR in S100a4-lineage cells (IRcKOS100a4) and assessed the effects on bone homeostasis at both young (15 weeks) and older adult (48 weeks) mice. S100a4-cre has previously been shown to target the perichondrium during bone development, and here we show that S100a4 is expressed by adult trabecular and cortical bone cells, and that S100a4-Cre effectively targets adult bone, resulting in efficient deletion of IR. Deletion of IR in S100a4-lineage cells does effect initial bone acquisition or homeostasis with no changes in cortical, trabecular or mechanical properties at 15-weeks of age, relative to wild type (WT) littermates. However, by 48-weeks of age, IRcKOS100a4 mice display substantial declines in trabecular bone volume, bone volume fraction and torsional rigidity, relative to age-matched WT controls. This work establishes the utility of using S100a4-cre to target bone and demonstrates that IR in S100a4-lineage cells is required for maintenance of bone homeostasis in adult mice.

cell biology↗

bioRxiv2017

Obesity/Type II Diabetes Promotes Function-Limiting Changes In Flexor Tendon Extracellular Matrix Organization That Are Not Reversed By Restoring Normal Metabolic Function

Type II Diabetes (T2DM) negatively alters baseline tendon function, including decreased range of motion and mechanical properties; however, the biological mechanisms that promote diabetic tendinopathy are unknown. To facilitate identification of therapeutic targets we developed a novel murine model of diabetic tendinopathy. Mice fed a High Fat Diet (HFD) developed diet induced obesity and T2DM. Obesity/ T2DM resulted in progressive impairments in tendon gliding function and mechanical properties, relative to mice fed a Low Fat Diet (LFD), as well as a decrease in collagen fibril diameter by transmission electron microscopy. We then determined if restoration of normal metabolic function, by switching mice from HFD to LFD, is sufficient to halt the pathological changes in tendon due to obesity/T2DM. However, switching from a HFD to LFD resulted in greater impairments in tendon gliding function than mice maintained on a HFD. Mechanistically, IR{beta} signaling is decreased in obese/T2DM murine tendons, suggesting altered IR{beta} signaling as a driver of diabetic tendinopathy. However, knock-down of IR{beta} expression in S100a4-lineage cells (IRcKOS100a4) was not sufficient to induce diabetic tendinopathy as no impairments in tendon gliding function or mechanical properties were observed in IRcKOS100a4 relative to WT. Collectively, these data define a murine model of diabetic tendinopathy, and demonstrate that tendon-specific, rather than systemic treatment approaches are needed.

pathology↗

bioRxiv2017

Deletion Of EP4 In S100a4-Lineage Cells Reduces Scar Tissue Formation During Early But Not Later Stages Of Tendon Healing

Tendon injuries heal via scar tissue rather than regeneration. This healing response forms adhesions between the flexor tendons in the hand and surrounding tissues, resulting in impaired range of motion and hand function. Mechanistically, inflammation has been strongly linked to adhesion formation, and Prostaglandin E2 (PGE2) is associated with both adhesion formation and tendinopathy. In the present study we tested the hypothesis that deletion of the PGE2 receptor EP4 in S100a4-lineage cells would decrease adhesion formation. S100a4-Cre; EP4flox/flox (EP4cKOS100a4) repairs healed with improved gliding function at day 14, followed by impaired gliding at day 28, relative to wild type. Interestingly, EP4cKOS100a4 resulted in only transient deletion of EP4, suggesting up-regulation of EP4 in an alternative cell population in these mice. Loss of EP4 in Scleraxis-lineage cells did not alter gliding function, suggesting that Scx-lineage cells are not the predominant EP4 expressing population. In contrast, a dramatic increase in -SMA+, EP4+ double-positive cells were observed in EP4cKOS100a4 suggesting that EP4cKOS100a4 repairs heal with increased infiltration of EP4 expressing -SMA myofibroblasts, identifying a potential mechanism of late up-regulation of EP4 and impaired gliding function in EP4cKOS100a4 tendon repairs.

cell biology↗

bioRxiv2017

Obesity/Type II Diabetes Alters Macrophage Polarization Resulting in a Fibrotic Tendon Healing Response

Type II Diabetes (T2DM) dramatically impairs the tendon healing response, resulting in decreased collagen organization and mechanics relative to non-diabetic tendons. Despite this burden, there remains a paucity of information regarding the mechanisms that govern impaired healing of diabetic tendons.\n\nMice were placed on either a high fat diet (T2DM) or low fat diet (lean) and underwent flexor tendon transection and repair surgery. Healing was assessed via mechanical testing, histology and changes in gene expression associated with collagen synthesis, matrix remodeling, and macrophage polarization. Obese/diabetic tendons healed with increased scar formation and impaired mechanical properties. Consistent with this, prolonged and excess expression of extracellular matrix (ECM) components were observed in obese/T2DM tendons. Macrophages are involved in both inflammatory and matrix deposition processes during healing. Obese/T2DM tendons healed with increased expression of markers of pro-inflammatory M1 macrophages, and elevated and prolonged expression of M2 macrophages markers that are involved in ECM deposition. Here we demonstrate that tendons from obese/diabetic mice heal with increased scar formation and increased M2 polarization, identifying excess M2 macrophage activity and matrix synthesis as a potential mechanism of the fibrotic healing phenotype observed in T2DM tendons, and as such a potential target to improve tendon healing in T2DM.

pathology↗