Biology subjects

Lemarie, E.

Publications and source records attributed to Lemarie, E..

4 recordsLinked to original sources

bioRxiv2026

Combined lactate and hypothermia therapy enhances neuroprotection following neonatal hypoxic-ischemic brain injury

Background and Purpose: Neonatal hypoxia-ischemia (NHI) is a leading cause of mortality and long-term neurodevelopmental disability. Therapeutic hypothermia (TH) is currently the only established treatment for NHI; however, its efficacy remains limited, underscoring the need for adjunctive neuroprotective strategies. Lactate is now regarded as a major metabolic substrate of the brain and has previously been shown to exert neuroprotective effects following experimental NHI. We investigated whether lactate enhances hypothermia-induced neuroprotection and evaluated the optimal timing of administration and potential underlying mechanisms. Methods: Postnatal day 7 Wistar rats were subjected to NHI using the Rice-Vannucci model and treated with TH alone (2h at 32{degrees}C), sodium L-lactate alone, or combined L-lactate-TH. Animals underwent longitudinal magnetic resonance imaging (MRI) and behavioral assessments, complemented by histological, immunohistochemical, and Western blot analyses, including assessment of protein lactylation. The effect of sodium L-lactate administration timing relative to TH was also evaluated. Results: Lactate significantly enhanced the neuroprotective effects of TH, particularly when administered before hypothermia, resulting in greater lesion recovery, reduced neuroinflammation and apoptotic cell death, preserved neuronal integrity, and improved long-term motor and cognitive outcomes. Combined treatment preserved neuronal lactate transporter, prevented NHI-induced astrocytic glutamate transporter upregulation, modulated lactylation markers, supporting coordinated metabolic and epigenetic adaptations following NHI. Conclusions: Early lactate administration enhances the neuroprotective efficacy of TH following NHI. These findings identify lactate as a promising adjunct to TH and support its translational potential as a metabolic strategy to improve outcomes following NHI brain injury.

neuroscience↗

bioRxiv2026

Intermittent Hypoxia Alters Cerebrovascular Recovery After Stroke

Stroke is a prevalent chronic disease, significantly contributing to mortality and long-term disability. The cerebrovascular recovery process after stroke can be complicated by certain comorbidities, including obstructive sleep apnea syndrome (OSA). However, the mechanisms underlying this deleterious impact of OSA on post-stroke recovery remain elusive. We conducted a preclinical study in rats submitted to stroke and intermittent hypoxia (IH), the main characteristic of OSA, to investigate the effects of IH on stroke lesion and to decipher the pathophysiological mechanisms of this stroke-OSA interaction. Using a malonate model of ischemic stroke on Sprague Dawley rats exposed to either normoxia or intermittent hypoxia for over 56 days, we monitored brain lesion size, microvascular plasticity and blood brain barrier (BBB) permeability using in vivo 4.7T-MRI. Finally, we assessed oxidative stress, inflammation, and angiogenesis-related gene expression by qPCR, and NeuN, GFAP, Collagen IV and ZO-1 expression by immunohistological staining. Our findings indicate that while IH does not significantly affect lesion volume reduction over time, it exacerbates ischemic injury-induced necrosis and neuronal loss. Additionally, IH amplifies post-stroke inflammation, as evidenced by increased IL-6 and TGF-{beta} expression, and induces oxidative stress by increasing DHE staining and decreasing Superoxide Dismutase (SOD1) level. Vascular assessment revealed IH-induced modifications in vessel radius and angiogenic factors expression (VEGF, Ang2), alongside increased BBB permeability and altered expression of aquaporin 1 and claudin 1, particularly in the acute phase post-stroke. These results suggest that IH alters cerebrovascular integrity and exacerbates inflammatory response following ischemic stroke, potentially contributing to poorer long-term functional outcomes. Understanding the mechanisms through which IH exacerbates post-stroke injury may guide the development of targeted neuroprotective strategies to improve stroke recovery in patients with OSA.

pathology↗

bioRxiv2025

Multimodal Characterization and Evolution of Malonate-induced Stroke Model: advanced MRI, Histology-Molecular Profiling

BackgroundIschemic stroke is a leading cause of mortality and disability worldwide, yet therapeutic options remain limited. Preclinical models play a crucial role in understanding stroke pathophysiology and evaluating potential treatments. This study aimed to provide a comprehensive characterization of the temporal evolution of ischemic injury induced by malonate intracerebral injection using multiparametric magnetic resonance imaging (MRI) combined with histological and molecular analysis. MethodsFocal ischemic lesions were induced by malonate injection in the striatum of rats. Lesion volume was monitored using T2-weighted MRI at multiple time points (Day 1, D7, D14, D28, and D56). Water content, reflecting vasogenic edema, was assessed via apparent diffusion coefficient (ADC) measurements, while vascular alterations were evaluated using blood volume fraction (BVF), vessel radius, and oxygen saturation (StO2). Blood-brain barrier (BBB) permeability was quantified through gadolinium-enhanced MRI. Molecular analyses by RT-qPCR were conducted to assess oxidative stress, inflammation, and angiogenesis-related gene expression. Immunohistological staining was performed to investigate neuronal loss, astrocytic activation, and vascular remodeling. ResultsMRI analysis showed a significant and progressive decrease in lesion volume. Water content increased from D4 onward. Ischemic injury significantly altered vascular function, leading to increased vessel radius and BVF while reducing tissue oxygenation. BBB permeability was elevated at D7 and D56, accompanied by increased claudin-1 and aquaporin-1 expression. Molecular analysis revealed an upregulation of inflammatory markers (IL-6, TGF-{beta}, NF-{kappa}B), oxidative stress response genes (SOD1, Nrf1), and impaired angiogenesis with increased Ang1/Ang2 but reduced VEGF/VEGFR1. Immunohistological analysis demonstrated neuronal loss, astrocytic activation, and vascular remodeling, characterized by increased ZO-1 and ColI-IV expression. ConclusionThe observed changes in lesion volume, vascular function, inflammation, oxidative stress, and angiogenesis highlight key mechanisms underlying post-stroke recovery. These findings emphasize the importance of long-term monitoring in preclinical stroke models and may contribute to the development of novel therapeutic strategies.

neuroscience↗

bioRxiv2021

A novel nanoluciferase transgenic reporter to measure proteinuria in zebrafish

The zebrafish is an important animal system for modelling human diseases. This includes kidney dysfunction as the embryonic kidney (pronephros) shares considerable molecular and morphological homology with the human nephron. Zebrafish also have a high fecundity, with females capable of laying 200-300 eggs per week, thereby facilitating chemical and mutation screening. A key clinical indicator of kidney disease is proteinuria, but a high-throughput readout of proteinuria in the zebrafish is lacking. Coupling the advantages of the zebrafish system with a tool to measure proteinuria will advance the scope for testing the efficacy of drugs to treat kidney diseases. Here, we generated a stable transgenic zebrafish line using the l-fabp10 liver-specific promoter to over-express a nanoluciferase molecule fused with the D3 domain of Receptor-Associated-Protein (RAP) to create NL-D3. In the healthy state, NL-D3 is excreted, but when embryos were treated with chemicals that affected either proximal tubular reabsorption (cisplatin, gentamicin) or glomerular filtration (angiotensin II, Hanks Balanced Salt Solution, Bovine Serum Albumin), NL-D3 presence in the urine increased. Similarly, depletion of several gene products associated with kidney disease (nphs1, nphs2, lrp2a, ocrl, col4a3, col4a4, and col4a5) also induced NL-D3 proteinuria. Furthermore, we found that treating col4a4 depleted zebrafish larvae (a model of Alport syndrome) with captopril reduced proteinuria. Our findings confirm the use of the NL-D3 transgenic zebrafish as a robust and quantifiable proteinuria reporter. Given the feasibility of high-throughput assays in zebrafish, this novel reporter will permit screening for drugs that ameliorate proteinuria and thereby prioritise candidates for further translational studies. Significance StatementThe zebrafish has become an important system for modelling kidney disease. However, proteinuria, an important clinical indicator of kidney dysfunction, is not easily detected in zebrafish. Here, we describe a transgenic line that uses a nanoluciferase reporter to enable detection of proteinuria in multiple models of glomerular and proximal tubular kidney disease in the zebrafish. In this system proteinuria can be accurately measured in a high-throughput manner and will enable the screening of drugs that affect glomerular filtration or protein re-uptake in the proximal tubule.

pathology↗