Biology subjects

Navarro, F. P.

Publications and source records attributed to Navarro, F. P..

4 recordsLinked to original sources

bioRxiv2025

Brain Infiltrated Monocyte-Macrophages in a rat model of Temporal Lobe Epilepsy: Revisiting the Pro-Inflammatory Paradigm

Neuroinflammation is central to temporal lobe epilepsy, yet the specific role of myeloid cells remains unclear. In status epilepticus (SE) models, circulating monocytes have been reported to infiltrate the brain, though distinguishing them from microglia remains challenging. Using a rat model, we traced infiltrating monocytes post-SE, to investigate their persistence, phenotypic evolution during epileptogenesis and contribution to neuroinflammation. By tracking phagocyted fluorescent nanoparticles and using CD68 immunohistochemistry, we confirmed that monocytes entered the brain in significant numbers 24 hours post-SE, after the inflammatory peak occurred (7h post-SE). Tracked up to 7 weeks, these cells adopted a microglia-like phenotype, contributed to the microglial scar and sustained low-grade inflammation during the chronic phase of epilepsy solely through their presence, as their expression of pro-inflammatory markers resembled that of non-activated microglia. Importantly, monocytes initially and transiently supported an anti-inflammatory response providing a unique opportunity to modulate neuroinflammation and potentially disrupt epilepsy progression, opening new avenues for therapeutic interventions.

neuroscience↗

bioRxiv2024

Second generation of LNP based mRNA vaccine leads to a T-cell-inflamed tumor microenvironment favorable for improving PD-1/PD-L1 blocking therapy and long-term immunity in a cold tumor model

The delivery of mRNA-based cancer vaccines has demonstrated significant promise in triggering antitumor immune responses. With the aim of using them in combination with other immunotherapies already used in the clinical appropriately, the modifications of the intratumoral immune microenvironment needs to be deeply characterized. We have shown that the second generation of lipid nanoparticles (LNPs), nanostructured lipid carriers (so-called Lipidots(R)), are able to vector protein antigens and nucleic acids. Here, we test Lipidots(R) for the delivery of mRNA encoding OVA antigen and eliciting a specific antitumor immune response. We demonstrate in vitro that our LNPs deliver mRNA into dendritic cells (DCs), when complexed with mRNA, activate DCs through the TLR4/8 and ROS signaling pathways and induce specific CD4+ and CD8+ T cell activation. Our vaccinal strategy exhibits significant antitumor efficacy both in the context of tumor prevention and as a therapeutic vaccine in B16OVA and E.G7-OVA cold tumors. The LNP-Ova mRNA vaccine induces a profound intratumoral remodeling of the innate and adaptive immunity associated with an increase in the gene expression of chemokines (Cxcl10, Cxcl11, Cxcl9) involved in CD8+ T cell attraction. Additionally, the vaccine induces the establishment of an escape mechanism mediated by PD-1/PDL-1 axis, making it an adjuvant therapy for optimized responses to the blocking of this signaling pathway. Finally, the combination of vaccine and anti-PD-1 therapy achieves a much higher rate of complete responses and memory immune responses compared to monotherapies. Our work demonstrates the capability of Lipidots(R) as an effective platform for the development of preventive and therapeutic vaccines against cancer based on mRNA delivery and that combination with other immunotherapies such as immune checkpoint blockers could counter tumor resistance and promote long-term antitumor immunity.

immunology↗

bioRxiv2021

Tuning the immunostimulation properties of cationic lipid nanocarriers for nucleic acid delivery

Nonviral systems, such as lipid nanoparticles, have emerged as reliable methods to enable nucleic acid intracellular delivery. The use of cationic lipids in various formulations of lipid nanoparticles enables the formation of complexes with nucleic acid cargo and facilitates their uptake by target cells. However, due to their small size and highly charged nature, these nanocarrier systems can interact in vivo with antigen-presenting cells (APCs), such as dendritic cells (DCs) and macrophages. As this might prove to be a safety concern for developing therapies based on lipid nanocarriers, we sought to understand how they could affect the physiology of APCs. In the present study, we investigate the cellular and metabolic response of primary macrophages or DCs exposed to the neutral or cationic variant of the same lipid nanoparticle formulation. We demonstrate that macrophages are the cells affected most significantly and that the cationic nanocarrier has a substantial impact on their physiology, depending on the positive surface charge. Our study provides a first model explaining the impact of charged lipid materials on immune cells and demonstrates that the primary adverse effects observed can be prevented by fine-tuning the load of nucleic acid cargo. Finally, we bring rationale to calibrate the nucleic acid load of cationic lipid nanocarriers depending on whether immunostimulation is desirable with the intended therapeutic application, for instance, gene delivery or messenger RNA vaccines.

immunology↗

bioRxiv2021

Low grade inflammation in the epileptic hippocampus contrasts with explosive inflammation occurring in the acute phase following status epilepticus in rats: translation to patients with epilepsy

There is still a lack of robust data, acquired identically and reliably from tissues either surgically resected from patients with mesial temporal lobe epilepsy (mTLE) or collected in animal models, to answer the question of whether the degree of inflammation of the hippocampus differs between mTLE patients, and between epilepsy and epileptogenesis. Here, using highly calibrated RTqPCR, we show that neuroinflammatory marker expression was highly variable in the hippocampus and the amygdala of mTLE patients. This variability was not associated with gender, age, duration of epilepsy, seizure frequency, and anti-seizure drug treatments. In addition, it did not correlate between the two structures and was reduced when the inflammatory status was averaged between the two structures. We also show that brain tissue not frozen within minutes after resection had significantly decreased housekeeping gene transcript levels, precluding the possibility of using post-mortem tissues to assess physiological baseline transcript levels in the hippocampus. We thus used rat models of mTLE, induced by status epilepticus (SE), that have the advantage of providing access to physiological baseline values. They indisputably indicated that inflammation measured during the chronic phase of epilepsy was much lower than the explosive inflammation occurring after SE, and was only detected when epilepsy was associated with massive neurodegeneration and gliosis. Comparison between the inter-individual variability measured in patients and that established in all epileptic and control rats suggests that some mTLE patients may have very low inflammation in the hippocampus, close to control values. However, the observation of elevated inflammation in the amygdala of some patients indicates that inflammation should be studied not only at the epileptic hippocampus, but also in the associated brain structures in order to have a more integrated view of the degree of inflammation present in brain networks involved in mesial temporal lobe epilepsy.

neuroscience↗