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Abstract Background Increasing evidence supports a key role for peripheral immune processes in the pathophysiology of Alzheimer’s disease (AD), highlighting an intricate interplay between brain resident glial cells and both innate and adaptive peripheral immune effectors. We previously showed that regulatory T cells (Tregs) have a beneficial impact on disease progression in AD-like pathology, notably by modulating the microglial response associated with Aβ deposits in a mouse model of amyloid pathology. Besides microglia, reactive astrocytes also play a critical role in neuroinflammatory processes associated with AD. Different phenotypes of reactive astrocytes have previously been characterized, including A1-like neurotoxic and A2-like neuroprotective subtypes. However, the precise impact of Tregs on astrocyte reactivity and phenotypes in AD still remains poorly defined. Methods We assessed the impact of Treg immunomodulation on astrocyte reactivity in a mouse model of AD-like amyloid pathology. Using 3D imaging, we carried out extensive morphological analyses of astrocytes following either depletion or amplification of Tregs. We further assessed the expression of several A1- and A2-like markers by immunofluorescence and RT-qPCR. Results Modulation of Tregs did not significantly impact the magnitude of global astrocyte reactivity in the brain nor in the close vicinity of cortical amyloid deposits. We did not observe changes in the number, morphology, or branching complexity of astrocytes according to immunomodulation of Tregs. However, early transient depletion of Tregs modulated the balance of reactive astrocyte subtypes, resulting in increased C3-positive A1-like phenotypes associated with amyloid deposits. Conversely, early depletion of Tregs decreased markers of A2-like phenotypes of reactive astrocytes associated with larger amyloid deposits. Intriguingly, modulation of Tregs also impacted the cerebral expression of several markers of A1-like subsets in healthy mice. Conclusions Our study suggests that Tregs contribute to modulate and fine-tune the balance of reactive astrocyte subtypes in AD-like amyloid pathology, by dampening C3-positive astrocytes in favor of A2-like phenotypes. This effect of Tregs may partly relate to their capacity at modulating steady state astrocyte reactivity and homeostasis. Our data further highlight the need for refined markers of astrocytes subsets and strategy of analysis for better deciphering the complexity of astrocyte reactivity in neurodegeneration.

Background Acute ischemic stroke is a neurologic emergency associated with severe disability and death. There is growing evidence that neutrophil extracellular traps (NETs) contribute to the pathogenesis of acute stroke. By mechanical removal of the occluding thrombus from the patient's vasculature, endovascular thrombectomy enables the collection of thrombus material for immunohistologic analysis. The aim of our study was to strengthen the association of NET content in ischemic thrombi with clinical outcome and guide future therapeutics. Methods We performed an immunohistologic analysis of thrombi from 101 patients with acute ischemic stroke, focusing on the association between NET content and clinical and interventional indicators. Results NETs were present in every patient with acute ischemic stroke. Their abundance in thrombi was associated with interventional markers of thrombus stability. NET‐rich thrombi were associated with unsuccessful recanalization (modified Thrombolysis in Cerebral Infarction

Abstract Background A dysregulated immune response is emerging as a key feature of critical illness in COVID-19. Neutrophils are key components of early innate immunity that, if not tightly regulated, contribute to uncontrolled systemic inflammation. We sought to decipher the role of neutrophil phenotypes, functions, and homeostasis in COVID-19 disease severity and outcome. Methods By using flow cytometry, this longitudinal study compares peripheral whole-blood neutrophils from 90 COVID-19 ICU patients with those of 22 SARS-CoV-2-negative patients hospitalized for severe community-acquired pneumonia (CAP) and 38 healthy controls. We also assessed correlations between these phenotypic and functional indicators and markers of endothelial damage as well as disease severity. Results At ICU admission, the circulating neutrophils of the COVID-19 patients showed continuous basal hyperactivation not seen in CAP patients, associated with higher circulating levels of soluble E- and P-selectin, which reflect platelet and endothelial activation. Furthermore, COVID-19 patients had expanded aged-angiogenic and reverse transmigrated neutrophil subsets—both involved in endothelial dysfunction and vascular inflammation. Simultaneously, COVID-19 patients had significantly lower levels of neutrophil oxidative burst in response to bacterial formyl peptide. Moreover patients dying of COVID-19 had significantly higher expansion of aged-angiogenic neutrophil subset and greater impairment of oxidative burst response than survivors. Conclusions These data suggest that neutrophil exhaustion may be involved in the pathogenesis of severe COVID-19 and identify angiogenic neutrophils as a potentially harmful subset involved in fatal outcome. Graphic Abstract

Background: Chemotherapy options in patients with advanced pancreatic ductal adenocarcinoma (PDAC) after failure of standard chemotherapies are limited. Objectives: We aimed to report the efficacy and safety of the leucovorin and 5-fluorouracil (LV5FU2) and carboplatin combination in this setting. Design: We performed a retrospective study including consecutive patients with advanced PDAC who received LV5FU2–carboplatin between 2009 and 2021 in an expert center. Methods: We measured overall survival (OS) and progression-free survival (PFS), and explored associated factors using Cox proportional hazard models. Results: In all, 91 patients were included (55% male, median age 62), with a performance status of 0/1 in 74% of cases. LV5FU2–carboplatin was mainly used in third (59.3%) or fourth line (23.1%), with three (interquartile range: 2.0–6.0) cycles administered on average. The clinical benefit rate was 25.2%. Median PFS was 2.7 months (95% CI: 2.4–3.0). At multivariable analysis, no extrahepatic metastases ( p = 0.083), no ascites or opioid-requiring pain ( p = 0.023), 18 months after initial diagnosis ( p

There is intensive research using gold nanoparticles for biomedical purposes, which have many advantages such as ease of synthesis and high reactivity. Their possible small size (