Periodic Reporting for period 3 - BrainDrain (Translational implications of the discovery of brain-draining lymphatics)
Período documentado: 2020-08-01 hasta 2022-01-31
In 2010, 800 billion Euros was spent on brain diseases in Europe and the cost is expected to increase due to the aging population. In this project we exploit our new discovery for research to alleviate this disease burden. In work selected by Nature Medicine among the top 10 ”Notable Advances” and by Science as one of the 10 ”Breakthroughs of the year” 2015, we discovered a meningeal lymphatic vascular system that serves brain homeostasis. We will reassess current concepts about cerebrovascular dynamics, fluid drainage and cellular trafficking in physiological conditions and in Alzheimer’s disease (AD) and neuroinflammation models in mice and in postmortem tissues in humans. First, we will study the development and properties of meningeal lymphatics and how they are formed and maintained. Then, we want to analyse the clearance of macromolecules and protein aggregates in mouse models of Alzheimer’s disease, and in mice that lack the newly discovered meningeal lymphatic drainage system. We examine if growth factor-mediated expansion of lymphatic vessels alleviates the parenchymal accumulation of neurotoxic molecules and brain disease pathogenesis and brain damage after traumatic brain injury. The meningeal lymphatics could be involved in a number of neurodegenerative and neuroinflammatory diseases of considerable human and socioeconomic burden. Several of our previous concepts have already been translated to clinical development and we aim to develop proof-of-principle therapeutic concepts in this project.
The main achievements so far concern the progress in the following objectives:
We demonstrated that essentially meningeal lymphatic vessels around the brain and spinal cord develop during the first postnatal month and that VEGFR3/VEGFC signaling is indispensable for their development and maintenance. We show that tuning the VEGFR3/VEGFC pathway by genetic and biochemical methods allows regression or expansion of meningeal lymphatic vessels in adulthood, resulting in a corresponding decrease or increase of cerebrospinal fluid clearance. We found the lymphatic network is extensive, it functions in transport of cerebrospinal fluid and it is plastic, reacting to injury or inflammation. Furthermore, we have developed multiple new and improved methods for imaging and analysis of the meningeal lymphatic vessels and their function, including imaging of whole cleared skull. We are further developing techniques that allow visualization of intracranial tracer flow. Investigation of the effects of VEGF-C and VEGFR-3 on cerebrospinal fluid flow and protein clearance is in progress.
We demonstrated a significant role of the main lymphangiogenic factor VEGF-C in regulation of cerebrospinal fluid (CSF) flow and drainage. Administration of VEGF-C protein immediately after stroke ensures faster recovery and improved behavioral outcome in mice. Analysis transgenic K14-sVEGFR3-Ig mice that lack lymphatic vessels has revealed a number of interesting changes in immune cells in CNS tissues.
We have also described and characterized meningeal lymphatics inrimates (marmosets). Ethical permission for autopsies has been obtained and collection of samples from meninges, draining extracranial lymphatic vessels and lymph nodes as well as from nasal mucosa has been initiated in collaboration with pathology and forensic medicine department.
We have characterized the role of meningeal lymphatic vessels in Alzheimer’s disease with two widely used mouse models. The basic characterization of tissues related to mLVs, namely dura mater, brain and cervical lymph nodes are analyzed at different time-points of disease course by IHC and functional drainage analysis. Initial results demonstrate that although same cell populations can be found at different disease progression states, changes occur especially in immune-cell expression profile.The exceptional dependence of meningeal lymphatic vessels the lymphangiogenic growth factor VEGF-C allows us to selectively modulate the amount and functionality of mLVs and study their role in Alzheimer’s disease.
In addition to the VEGFC-VEGFR3 signaling pathway, Angiopoietin (Ang)-Tie signaling pathway plays important roles in regulating vascular permeability and leukocyte trafficking. Experimental autoimmune encephalomyelitis (EAE) is a well-characterized experimental model of multiple sclerosis (MS), which is the most common human demyelinating CNS autoimmune disease. We found that neuroinflammation induces the expression of Ang2. Transgenic mice expressing Ang2 specifically in ECs developed a more severe EAE than control mice whereas both prophylactic and preemptive treatment with an Ang2-blocking antibody ameliorates EAE. Thus, Ang2 targeting may serve as an alternative therapeutic option for the treatment of CNS autoimmune diseases.
Our results reveal that mLVs in the dura almost completely regressed as a result of inhibition of VEGFR3 signaling. However, to our surprise, the lack of mLVs in the skull cap did not alter the clinical severity of EAE or the percentage of body weight loss. Therefore, further studies are now under consideration to determine the exact contribution of mLVs at different anatomic locations to the progression of CNS autoimmune diseases and how this knowledge could be translated into the treatment of CNS autoimmune diseases.
Our current results (in collaboration with Dr. Francesco Noe) shows that mLVs are pivotal for a proper and specific neuro-immune response after TBI, which is principally mediated by the resident memory cytotoxic CD8+ T cells.
We demonstrated that essentially meningeal lymphatic vessels around the brain and spinal cord develop during the first postnatal month and that VEGFR3/VEGFC signaling is indispensable for their development and maintenance. We show that tuning the VEGFR3/VEGFC pathway by genetic and biochemical methods allows regression or expansion of meningeal lymphatic vessels in adulthood, resulting in a corresponding decrease or increase of cerebrospinal fluid clearance. We found the lymphatic network is extensive, it functions in transport of cerebrospinal fluid and it is plastic, reacting to injury or inflammation. Furthermore, we have developed multiple new and improved methods for imaging and analysis of the meningeal lymphatic vessels and their function, including imaging of whole cleared skull. We are further developing techniques that allow visualization of intracranial tracer flow. Investigation of the effects of VEGF-C and VEGFR-3 on cerebrospinal fluid flow and protein clearance is in progress.
We demonstrated a significant role of the main lymphangiogenic factor VEGF-C in regulation of cerebrospinal fluid (CSF) flow and drainage. Administration of VEGF-C protein immediately after stroke ensures faster recovery and improved behavioral outcome in mice. Analysis transgenic K14-sVEGFR3-Ig mice that lack lymphatic vessels has revealed a number of interesting changes in immune cells in CNS tissues.
We have also described and characterized meningeal lymphatics inrimates (marmosets). Ethical permission for autopsies has been obtained and collection of samples from meninges, draining extracranial lymphatic vessels and lymph nodes as well as from nasal mucosa has been initiated in collaboration with pathology and forensic medicine department.
We have characterized the role of meningeal lymphatic vessels in Alzheimer’s disease with two widely used mouse models. The basic characterization of tissues related to mLVs, namely dura mater, brain and cervical lymph nodes are analyzed at different time-points of disease course by IHC and functional drainage analysis. Initial results demonstrate that although same cell populations can be found at different disease progression states, changes occur especially in immune-cell expression profile.The exceptional dependence of meningeal lymphatic vessels the lymphangiogenic growth factor VEGF-C allows us to selectively modulate the amount and functionality of mLVs and study their role in Alzheimer’s disease.
In addition to the VEGFC-VEGFR3 signaling pathway, Angiopoietin (Ang)-Tie signaling pathway plays important roles in regulating vascular permeability and leukocyte trafficking. Experimental autoimmune encephalomyelitis (EAE) is a well-characterized experimental model of multiple sclerosis (MS), which is the most common human demyelinating CNS autoimmune disease. We found that neuroinflammation induces the expression of Ang2. Transgenic mice expressing Ang2 specifically in ECs developed a more severe EAE than control mice whereas both prophylactic and preemptive treatment with an Ang2-blocking antibody ameliorates EAE. Thus, Ang2 targeting may serve as an alternative therapeutic option for the treatment of CNS autoimmune diseases.
Our results reveal that mLVs in the dura almost completely regressed as a result of inhibition of VEGFR3 signaling. However, to our surprise, the lack of mLVs in the skull cap did not alter the clinical severity of EAE or the percentage of body weight loss. Therefore, further studies are now under consideration to determine the exact contribution of mLVs at different anatomic locations to the progression of CNS autoimmune diseases and how this knowledge could be translated into the treatment of CNS autoimmune diseases.
Our current results (in collaboration with Dr. Francesco Noe) shows that mLVs are pivotal for a proper and specific neuro-immune response after TBI, which is principally mediated by the resident memory cytotoxic CD8+ T cells.
Our top-ranking discovery that the brain is served by an elaborate system of meningeal lymphatic vessels challenges opens up a possibility to address a totally new area of biomedical research.
With our discovery, the concept of how the brain drainage and immune systems should be targeted for disease benefit is likely to be dramatically changed, thus greatly influencing the development of novel therapeutic targets. This project could spin off useful biomarkers and indicators for clinical pathology, patient stratification and personalized medicine. Our studies could also spin off genetic and epigenetic risk factors that may alter normal brain function and predispose to neurologic disease through dysfunctional lymphatic circulation. - My research group has previously invented and patented vascular technology that has so far led to a startup company and altogether three clinical trials, thus our credibility in translational biomedical research should be high.
The ambitious objective of my plan is to elucidate the development and physiological function of meningeal lymphatic vasculature, to characterize its role in the pathogenesis of neurodegenerative and neuroinflammatory diseases, and to explore the new translational diagnostic and therapeutic potential of lymphangiogenic growth factors in these diseases. This research will have a global impact by incorporating new concepts into the state-of-the-art in human physiology and into neurodegenerative and neuroinflammatory pathogenesis research to bring it to a new level.
With our discovery, the concept of how the brain drainage and immune systems should be targeted for disease benefit is likely to be dramatically changed, thus greatly influencing the development of novel therapeutic targets. This project could spin off useful biomarkers and indicators for clinical pathology, patient stratification and personalized medicine. Our studies could also spin off genetic and epigenetic risk factors that may alter normal brain function and predispose to neurologic disease through dysfunctional lymphatic circulation. - My research group has previously invented and patented vascular technology that has so far led to a startup company and altogether three clinical trials, thus our credibility in translational biomedical research should be high.
The ambitious objective of my plan is to elucidate the development and physiological function of meningeal lymphatic vasculature, to characterize its role in the pathogenesis of neurodegenerative and neuroinflammatory diseases, and to explore the new translational diagnostic and therapeutic potential of lymphangiogenic growth factors in these diseases. This research will have a global impact by incorporating new concepts into the state-of-the-art in human physiology and into neurodegenerative and neuroinflammatory pathogenesis research to bring it to a new level.