Publications by authors named "Alexis Combes"

Human immune systems are highly variable, with most variation attributable to non-genetic sources. The gut microbiome crucially shapes the immune system; however, its relationship with the baseline immune states of healthy humans remains incompletely understood. Therefore, we performed multi-omic profiling of 110 healthy participants through the ImmunoMicrobiome study.

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  • - This study focused on developing a new imaging-based method called single-cell spatial transcriptomics (iSCST) to analyze archived, formalin-fixed, paraffin-embedded (FFPE) tissue samples from inflammatory bowel disease (IBD) patients, which helps to preserve the spatial context of various cell types within the tissue.
  • - Researchers benchmarked three iSCST platforms by analyzing 57 FFPE mucosal biopsies from IBD patients and healthy controls, allowing for detailed cell analysis and gene expression profiling through a consistent data processing pipeline.
  • - A custom gene panel showed the best performance for detecting and quantifying different cell subsets, revealing significant findings related to inflammation and treatment responses in ulcerative colitis, which could enhance
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CD206 is a common marker of a putative immunosuppressive "M2" state in tumor-associated macrophages (TAMs). We made a novel conditional CD206 (Mrc1) knock-in mouse to specifically visualize and/or deplete CD206+ TAMs. Early depletion of CD206+ macrophages and monocytes (Mono/Macs) led to the indirect loss of conventional type I dendritic cells (cDC1), CD8 T cells, and NK cells in tumors.

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Chronic inflammation and tissue fibrosis are common responses that worsen organ function, yet the molecular mechanisms governing their cross-talk are poorly understood. In diseased organs, stress-induced gene expression changes fuel maladaptive cell state transitions and pathological interaction between cellular compartments. Although chronic fibroblast activation worsens dysfunction in the lungs, liver, kidneys and heart, and exacerbates many cancers, the stress-sensing mechanisms initiating transcriptional activation of fibroblasts are poorly understood.

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Objective: To investigate if a positive result on ReceptivaDx for evaluation of B-cell lymphoma 6 (BCL6), a proposed marker of progesterone resistance associated with impaired uterine receptivity, correlates with a suboptimal profile of receptivity-associated markers in the window of implantation using the endometrial receptivity array and single-nucleus transcriptomic analysis.

Design: Retrospective clinical cohort study; pilot study of single-nucleus RNA sequencing of prospectively collected window of implantation endometrium undergoing ReceptivaDx BCL6 evaluation.

Setting: Academic center.

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  • - Germinal matrix hemorrhage (GMH) is a serious condition in preterm infants linked to blood vessel rupture in the brain, but the reasons behind this vulnerability are not well understood.
  • - Research shows that microglia (immune cells in the brain) interact with developing blood vessels differently as the brain matures and their absence can hinder blood vessel growth in key brain areas.
  • - In preterm infants with GMH, immune cells show abnormal activation, leading to inflammation and factors that compromise blood vessel integrity, suggesting that the immune response plays a crucial role in the development of GMH.
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  • Tumor progression leads to fibrosis, which involves excessive buildup of extracellular matrix and reduces immune cell infiltration, particularly affecting CD8 T cells.
  • Tumor-associated macrophages (TAMs) adapt to the stiff fibrotic environment by promoting collagen production through signaling from transforming growth factor-β.
  • This collagen production by TAMs creates a challenging metabolic environment that limits the effectiveness of CD8 T cells, hindering their ability to mount strong antitumor responses in breast cancer patients.
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  • Colitis caused by checkpoint inhibitors (CPI) is common and typically treated with steroids, but its mechanisms in patients who have used steroids or do not respond to them are not well understood.
  • Researchers analyzed biopsies and blood samples from mainly steroid-experienced CPI colitis patients using advanced techniques to identify contributing immune cell populations.
  • The study found increased levels of specific T cells linked to the colitis, and highlighted unique features of CPI colitis metabolism and potential targets for treatment, suggesting CD4 memory T cells and certain endothelial cells could be key in managing this disease.
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  • TGFβ is a molecule that helps tumors hide from the immune system and impacts how cancer cells behave. When TGFβ signaling is lost, it makes tumors more damaged and more likely to respond to treatments that attack their DNA.
  • Researchers found that tumors with high levels of damage (called βAlt) could be treated better with immune therapies, but many of these tumors actually had fewer immune cells around them despite their damage.
  • In studies, they discovered that combining treatments like radiation and blocking TGFβ could help these immune-poor tumors attract immune cells and respond better to therapies that use the immune system.
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Ulcerative colitis (UC) is driven by immune and stromal subsets, culminating in epithelial injury. Vedolizumab (VDZ) is an anti-integrin antibody that is effective for treating UC. VDZ is known to inhibit lymphocyte trafficking to the intestine, but its broader effects on other cell subsets are less defined.

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Background: Acute lung allograft dysfunction (ALAD) is an imprecise syndrome denoting concern for the onset of chronic lung allograft dysfunction (CLAD). Mechanistic biomarkers are needed that stratify risk of ALAD progression to CLAD. We hypothesized that single cell investigation of bronchoalveolar lavage (BAL) cells at the time of ALAD would identify immune cells linked to progressive graft dysfunction.

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  • Hematopoiesis is the process where our body makes different types of blood cells from special cells called multipotent hematopoietic stem cells (HSC).
  • Researchers studied how changes in certain genes, like KRAS and RasGRP1, affect these blood cells and found that these changes can cause an imbalance, making more of some types of blood cells than others.
  • They discovered that RasGRP1 helps keep some stem cells in a resting state, while KRAS reduces these resting cells, showing how different genes can change how our blood cells develop.
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The bone marrow is the main site of blood cell production in adults, however, rare pools of hematopoietic stem and progenitor cells with self-renewal and differentiation potential have been found in extramedullary organs. The lung is primarily known for its role in gas exchange but has recently been described as a site of blood production in mice. Here, we show that functional hematopoietic precursors reside in the extravascular spaces of the human lung, at a frequency similar to the bone marrow, and are capable of proliferation and engraftment.

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Tumor-associated macrophages (TAMs) are frequently categorized as being 'M1' or 'M2' polarized, even as substantial data challenges this binary modeling of macrophage cell state. One molecule consistently referenced as a delineator of a putative immunosuppressive 'M2' state is the surface protein CD206. We thus made a novel conditional CD206 () knock-in mouse to specifically visualize and/or deplete CD206+ 'M2-like' TAMs and assess their correspondence with pro-tumoral immunity.

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  • Altered myeloid inflammation and lymphopenia are key characteristics of severe infections, particularly in patients with acute lung injuries from SARS-CoV-2.
  • The upregulated EN-RAGE gene program found in airway and blood myeloid cells is linked to increased clinical severity, predicting outcomes like mechanical ventilation and mortality.
  • IL-6 was identified as a major factor driving myeloid dysfunction, and blocking its signaling with tocilizumab effectively normalized EN-RAGE gene expression and improved T cell function in clinical trials.
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Antitumor immunity is driven by CD8 T cells, yet we lack signatures for the exceptional effectors in tumors, amongst the vast majority of CD8 T cells undergoing exhaustion. By leveraging the measurement of a canonical T cell activation protein (CD69) together with its RNA (), we found a larger classifier for TCR stimulation-driven effector states and . This revealed exceptional 'star' effectors-highly functional cells distinguished amidst progenitor and terminally exhausted cells.

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  • High-dimensional single-cell technologies have become essential for studying the immune system, but analyzing the resulting data is complex and computationally demanding.
  • The authors introduce Cyclone, an analysis pipeline that simplifies and optimizes clustering and visualization of cytometry data across different techniques and biological contexts.
  • Cyclone not only matches the accuracy of established immune cell identification methods but also helps discover new subsets of immune cells linked to specific biological characteristics, enhancing immunology research.
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  • Tumours exist in a complex immune environment that can either help or hinder their growth, challenging the idea that all tumours share a single immune profile needing treatment.
  • Recent research has shown that there are multiple immune states surrounding tumours, with around 12 major 'dominant' immune archetypes that recur across different cancers.
  • Understanding these archetypal TMEs can reveal specific weaknesses that could be targeted for cancer therapies, while also anticipating potential side effects for patients.
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  • Scientists studied how different cells work together to heal skin wounds over time.
  • They discovered patterns in how genes are turned on and off during this healing process, which they called "movements."
  • They also found similar healing patterns in tumors, suggesting that tumors behave like wounds that don’t completely heal.
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Intratumoral heterogeneity (ITH)-defined as genetic and cellular diversity within a tumor-is linked to failure of immunotherapy and an inferior anti-tumor immune response. The underlying mechanism of this association is unknown. To address this question, we modeled heterogeneous tumors comprised of a pro-inflammatory ("hot") and an immunosuppressive ("cold") tumor population, labeled with YFP and RFP tags respectively to enable precise spatial tracking.

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  • High-dimensional single cell technologies have transformed immunology research, enabling scientists to study the immune system more effectively.
  • Cyclone is a new analysis pipeline that integrates necessary tools for data processing, such as dimensionality reduction and clustering, making it easier to analyze complex cytometry data.
  • Cyclone has been tested on various cytometry techniques and has been shown to accurately identify immune cell types, facilitating further research and discoveries in immunology.
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CD8 T cell responses are critical for anti-tumor immunity. While extensively profiled in the tumor microenvironment, recent studies in mice identified responses in lymph nodes (LNs) as essential; however, the role of LNs in human cancer patients remains unknown. We examined CD8 T cells in human head and neck squamous cell carcinomas, regional LNs, and blood using mass cytometry, single-cell genomics, and multiplexed ion beam imaging.

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Unlabelled: α-Fetoprotein (AFP) is expressed by stem-like and poor outcome hepatocellular cancer tumors and is a clinical tumor biomarker. AFP has been demonstrated to inhibit dendritic cell (DC) differentiation and maturation and to block oxidative phosphorylation. To identify the critical metabolic pathways leading to human DC functional suppression, here, we used two recently described single-cell profiling methods, scMEP (single-cell metabolic profiling) and SCENITH (single-cell energetic metabolism by profiling translation inhibition).

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  • The study explored how the airway epithelium responds to SARS-CoV-2 and its variants, using airway organoids from 20 different subjects to better understand infection mechanisms.* -
  • Tetraspanin-8 (TSPAN8) was identified as a key factor that enhances SARS-CoV-2 infection, working independently of the ACE2-Spike protein interaction.* -
  • Although Delta and Omicron variants showed lower infection rates than the original virus, they still altered the epithelial response, indicating potential new targets for COVID-19 treatments with TSPAN8-blocking antibodies.*
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Ulcerative colitis (UC) is driven by immune and stromal subsets, culminating in epithelial injury. Vedolizumab (VDZ) is an anti-integrin antibody that is effective for treating UC. VDZ is known to inhibit lymphocyte trafficking to the intestine, but its broader effects on other cell subsets are less defined.

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