Mechanosensing by meningeal macrophages and its impact on neuroinflammation
Due to the vital importance of the brain, its infection and inflammation have to be tightly controlled. The brain surface is connected to the skull by highly vascularized membranes, the meninges, that are prone to inflammation, following neuroinfection. In the case of viral meningitis, this leads to blood leakage, increased intracranial pressure and fatal herniation. The goal of this project is to understand how meningeal macrophages (MM), the most abundant immune population, respond to an increase in intracranial pressure and whether this is beneficial to the host upon infection. To this aim, we will combine innovative strategies to visualize, manipulate and characterize the behavior of MM in vitro, in different conditions of pressure/microbial stimulation. We will extend our results in vivo, in mice infected with lymphocytic choriomeningitis virus (LCMV). This pioneer work will help understand the understudied mechanical properties of the brain defense system and may provide new avenues to design therapeutic strategies.
LCMV, macrophages, TRPV, mechanotransduction, pressure
1/ Define the mechanical properties of MM in vitro in response to different pressures and microbial stimulation, and their functional outcome in terms of macrophage activation (calcium induced-production of chemokines or vasoactive peptides) or macrophage death.
2/ Understand the molecular mechanisms allowing mechanical sensing and signal transduction.
3/ Evaluate the in vivo relevance of our findings, in the context of viral meningitis.
Proposed approach (experimental / theoretical / computational)
Preliminary data indicate that MM are equipped with mechanoreceptors and are activated by increased hydrostatic pressure. Also, they have specific membrane and cytoskeleton properties.
1/ We will sort MM populations from the meningeal tissue of wild-type mice and measure their mechanical properties and their response to pressure (Fura2 calcium imaging and single cell RNA sequencing), using force-based biophysical techniques (indenter and pressure-controlled chamber). We will use a range of hydrostatic pressures from 7 (steady-state) to 25 mmHg (pathological edema), with and without microbial stimulation.
2/ Upstream receptors/regulators of high pressure-MM transcriptome will be analyzed in silico and validated in vitro using genetic and pharmacological tools.
3/ We will use knock-out mice and transcranial receptor inhibition upon LCMV infection, and will follow the course of the infection (MM activation state, recruitment of immune cell types, viral load, edema, death).
This project is interdisciplinary as it requires:
1- The biomechanical expertise of Dr. Valignat in the LAI lab. She routinely uses pressure-controlled chambers and calcium probes that will be important to measure MM properties (elasticity, maximal load, activation). The indenter, a new acquisition of the Centuri program, will also be used.
2- The immunopathology and virology expertise of Dr. Rua. I have already described the key virological and immunological parameters involved in the control of LCMV neuroinfection, and we will be able to follow those parameters upon MM manipulation (inhibition of mechanosignal transduction).
3- The bioinformatics expertise of the CIML genomic facility (Dr. Rua’s Institute). In silico analysis of the upstream transcriptomic regulators of high-pressure MM will be needed to infer the activation state and transduction signaling pathways involved in MM response to intracranial pressure.
We are looking for a candidate with either an immunology/virology background, or with a biophysics background. The PhD candidate should be able to learn fast and adapt to different environments. He/She should be fluent in English or/and French.