PATHOPHYSIOLOGY OF CHRONIC INFLAMMATORY DISORDERS AND RELATED BIOTHERAPIES

Acronym: PACIDbio  

Coordinators : AUSSEIL Jérôme and POUPOT Remy

 

Scientific Objectives


Chronic inflammatory and neuro-inflammatory diseases are characterized by a dysregulated and imbalanced immune system. Among all immune cells, myeloid cells emerge as important players in several inflammatory diseases because of their ability to promote inflammation and oxidative stress in addition to their skill to detect and mitigate pathogenic states. Our team is interested in microglia in the brain and in monocytes / macrophages in tissues that are also confronted with chronic local inflammations such as: bone, joint and the kidneys. Microglia and macrophages establish interactions with neighboring tissue cells (by releasing mediators or not), and influence their activities not only under pathological conditions, but also under physiological conditions, especially during development, homeostatic tissue processes, tissue repair, and immunity. Playing major roles in the initiation and propagation of the chronic inflammation including neuro-inflammation, microglia as well as monocytes / macrophages are therefore relevant therapeutic targets.

Our research interests are focused on the pathophysiology of inflammatory and neuro-inflammatory disorders, and on the design and the development of new biotherapies and their implementation at the preclinical and clinical steps.

 

 

 

 

 

 

 

 

 


Axis 1: Pathophysiology and gene therapy for Sanfilippo syndrome, a paediatric neurodegenerative disease

Sanfilippo syndrome (also referred as Mucopolysaccharidosis IIIB) is characterized by severe neuro-inflammation and neurodegeneration caused by the deficiency of a lysosomal exoglycanase leading to the interruption of heparan sulfate (HS) degradation. The progressive accumulation of HS Oligosaccharides (HSOs) induces oxidative stress development, cytokine and chemokine production via a TLR4-dependent activation in the central nervous system (CNS) (Trudel, J Neurosci Res 2015) and in the osteoarticular system. The activation of TLR-4 induces microglial STAT3 signalling pathway activation leading to increase expression of hepcidin and brain iron retention (Puy, Glia 2018). We are currently studying the functional and molecular status of microglia in this syndrome. We are also elucidating the role of microglia in the initiation and the propagation of inflammation leading to the neurodegenerative processes in our models (murine BV2 and primary adult microglia, human CHME-5 microglia and Sanfilippo B mouse models). Microglia-derived extracellular vesicle (EVs) are suggested to be involved in propagation of inflammatory signals in brain. However, little is known about the biogenesis and the regulation of EVs production. Using biochemical and proteomic approaches, we aim at studying the production, composition and role of EVs produced by microglia during neuro-inflammation. There is currently no therapy for these diseases. In collaboration with teams from the Institut Pasteur and the APHP, we participated in a first phase I / II clinical trial of intracerebral gene therapy on 4 Sanfilippo B children, the results of which are very encouraging. However, the neurocognitive benefit was only partial, probably because the enzyme is not delivered to the periphery of the brain.

Our team is now launching a new preclinical study on animal models combining intracerebral and peripheral administration of a new vector crossing the blood brain barrier. If the results are convincing, a new clinical trial will be scheduled. This project is funded by the association Vaincre les Maladies Lysosomales.

Axis 2: Pathophysiology of Parkinson disease and new anti-inflammatory therapies for neurodegenerative diseases

“Reactive microgliosis” is now considered the causal agent of neuro-inflammation that leads to neurodegeneration in several diseases linked to ageing (among which Alzheimer’s Disease and Parkinson’s Disease, PD). Part of our research is to decipher the mechanisms and kinetics leading to “reactive microgliosis” in PD using mouse model thereof.
We are also designing new therapeutic approaches to treat chronic inflammation by targeting myeloid cells (monocytes/macrophages, dendritic cells, …). We have shown that immuno-modulatory phosphorus-based dendrimers such as the ABP dendrimer are able to switch the pro-inflammatory activation of monocytes/macrophages to an anti-inflammatory phenotype. We have proven the therapeutic efficacy of these molecules in several mouse models of chronic inflammatory diseases (Rheumatoid Arthritis, Multiple Sclerosis, …). Now we want to test the therapeutic efficacy of the ABP dendrimer (or of bio-active analogues) in mouse models of neurodegenerative diseases. The cellular and molecular mechanisms underpinning the therapeutic efficacy of the dendrimers, if any, will be delineated.
In parallel, we are collaborating with Michel Simon’s team at INFINITy to take advantage of the anti-inflammatory properties of phosphorus-based dendrimers to treat skin inflammatory diseases, and in particular psoriasis, by topical application of the dendrimers.

Axis 3. Iron metabolism and hepcidin in chronic inflammatory diseases

Iron that is present in all cells of the body, is necessary for life (oxygen transport, electron transfer reactions, or DNA synthesis). Physiological iron is used mainly to produce heme, the prosthetic group of hemoproteins such as hemoglobin, myoglobin and cytochrome P450. However, excess of iron represents a real threat for the cell since it is able to generate free radicals (ROS) during the Fenton reaction (chemical reaction using  iron and oxygenated water to produce hydroxyl radical: H2O2 + Fe2+ “OH + OH + Fe3+).  Iron is also incriminated to promote pathogen infection. In the body, iron balance is ensured by a strict equilibrium between its absorption from the diet and its storage by macrophages. Both intestinal absorption and macrophages release of iron are controlled by hepcidin, a small peptide synthesized and secreted by the liver. The expression of hepcidin is regulated by iron variations in the body (induced in iron overload and repressed by iron deficiency and stimulated erythropoiesis). In addition, being an acute phase protein, hepcidin in induced by inflammation, which in pathology contributes to functional iron deficiency and anemia of inflammation. Hepcidin is also expressed in many other organs, albeit at a much lower level (Kidney, brain, bone, monocytes/macrophages).

 

The main goal of this axis is to develop research leading to elucidate the role of extrahepatic hepcidin in infection/inflammation process and in pathologies facing oxidative stress due to the uncontrolled inflammatory iron accumulation both in mouse models and in patients. Currently, our priorities is kidney diseases (anemia of inflammation, urinary tract infection), neuroinflammation (Sanfilippo syndrome) and bone/joint (Rheumatic disease).

Axis 4: Bone remodeling, arthritis and therapeutics

Myeloid cells (monocytes, dendritic cells, macrophages and osteoclasts) play a central role in the pathogenesis of inflammatory osteo-articular diseases such as Rheumatoid Arthritis or Psoriatic Arthritis. They are notably involved in joint inflammation, structural damage, and inflammation-induced osteoporosis. We aim at better characterizing the involvement of myeloid cells and at investigating the impact of disease-modifying anti-rheumatic drugs (DMARDs) on these cells in inflammatory rheumatic diseases.

Our strong connection to the Rheumatology department of Toulouse University Hospital and to the national Rheumatology network of University Hospitals allows an access to local (BIOTOUL) and national clinical databases and biobanks involving patients with Rheumatoid arthritis (ESPOIR cohort), Psoriatic Arthritis (APACHE cohort), Spondyloarthritis (DESIR cohort) and Systemic mastocytosis (CEREMAST).

 

Currently, we are investigating: 1)- the impact of DMARDs on macrophage polarization and osteoclastogenesis in the context of inflammatory osteo-articular diseases. 2)- the mechanisms of TNF reverse signalling induced by anti-TNF agents and its implication in clinical response to anti-TNF agents. 3)- the role of hepcidin in joint inflammation and bone remodelling during arthritis;

Axis 5 : Prader Willi Syndrome (PWS), neurodevelopment and epigenetics

Prader Willi Syndrome (PWS) is a rare neuro-developmental disease with a severe eating disorder and behavioral disturbances. We study PWS pathophysiology in the context of the National Reference Center for PWS, in Toulouse Children’s University Hospital coordinated by M. Tauber. We use complementary approaches with on-going clinical research studies and cellular models with iPSC (induced Pluripotent Stem Cells) from PWS patients. Some reports suggest an implication of SNORD116 in neuro-inflammation and neurodegeneration in PWS.

Specifically, we study the role of a small nucleolar RNA, SNORD116, with respect to neuroendocrine and endocrine abnormalities in PWS. Using specific hypothalamic neurons derived from iPSC of a patient with highly limited SNOD116 deletion (MD) (Am J Hum Genet, 2015) we have contributed to the demonstration of the role of SNORD116 in the processing of several prohormones (J Clin Invest, 2017; Coll. R. Liebel, Columbia Un. USA).

Our most recent results demonstrate the impact of SNORD116 and IGFBP7 on growth hormone therapy in PWS (Genet Med, 2021). Further studies are conducted in order to elucidate the molecular mechanisms involved.

A major topic is the role of hypothalamic dysfunction, especially related to ghrelin and oxytocin (OXT) pathways with therapeutics perspective as demonstrated by the beneficial effects of OXT administrated to PWS infants (Pediatrics, 2018 and Rev. in Lancet Diabetes Endocrinol, 2021). Ghrelin and OXT pathways in PWS in relation with SNORD116 deletion are also highly involved in addiction, food intake and behavioral disturbances, potentially linked to epigenetic modifications (Mol Psychiatry, 2020 and Transl Psychiatry, 2020).

A prospective study with placebo for the effect of OXT in infants is developed in the context of a European Trial PEDCRIN (OTBB3 Trial PedCRIN H2020 GA- N° 731046 4), supported by the startup OT4B. This study will be one support for clarifying the impact of SNORD116 and PWS on epigenetic processes in pathways underlying the dopaminergic circuit of recompense involved in addiction and social interaction (J. Salles, PhD thesis).

Another topic addresses the role of ghrelin disturbances and hormone resistance in bone metabolism. With respect to pathophysiology of scoliosis frequently observed in PWS, the molecular mechanism implicating cellular resistance are tested in models of osteoblasts (Biochim. Biophys. Acta, 2020 and Biochem Biophys Rep, 2020). This is connected with the Reference Center of the Metabolism of Calcium and Phosphate and ERN Bone coordinated by J.P. Salles.

Axis 6 : AlterAG, a new pathway for the synthesis of the endocannabinoid 2-arachidonoylglycerol in infectious and inflammatory pathologies

The discovery of endocannabinoid system (ECS), as revealed through studies of the most potent psychotropic compound from Cannabis sativa, D-9-tetrahydrocannabinol (THC), has opened a novel area of pharmacology suggesting its therapeutic potential in various pathological conditions. The ECS consists of cannabinoid receptors, their endogenous ligands (endocannabinoids) and proteins controlling their synthesis and degradation. To date, two cannabinoid receptors (CB1 and CB2) have been identified. They are cell membrane receptors containing seven transmembrane domains and they belong to the G-protein-coupled receptors family. Their expression is tissue specific since CB1 is mainly located in the central nervous system while CB2 is mainly expressed in the immune system. The two receptors are activated by endogenous lipid mediators that are released « on demand » in response to diverse physiological and pathological stimuli. Cannabinoids have pleiotropic activities like anti-inflammatory, immunomodulatory and neuroprotective properties. We have discovered a new pathway for the synthesis of the main endocannabinoid, 2-arachidonoylglycerol (2-AG), the full agonist of both receptors. This involves the hydrolysis by a lysophospholipase C called GDE3 (GDPD2 gene) of lysophosphatidylinositol (LPI), which is itself a ligand of a third type of endocannabinoid receptor (GPR55). GDE3 is expressed in particular in splenic red pulp fibroblasts, small intestine enterocytes, skin and a subpopulation of astrocytes.

Taking advantage of the use of mice invalidated for GDPD2 (GDE3-KO), we have shown a role of GDE3 in the defense against circulating bacteria, especially in the spleen. GDE3 could also contribute to neuro-inflammatory processes by intervening at two levels: small intestine, where it is essential for maintaining intestinal barrier integrity and microbiota balance, central nervous system, where it ensures the production of 2-AG on specific sites which remain to be identified.

The objective of this axis is to investigate the role of GDE3 and the mechanisms involved in several murine models of infectious and inflammatory pathologies of the gastrointestinal tract, brain (Experimental Autoimmune Encephalomyelitis or EAE, Parkinson’s disease and Sanfilippo syndrome), skin (psoriasis) and immune system. The involvement of the alternative pathway of 2-AG production, which we call Alter-AG, could thus provide interesting pharmacological targets to be explored in the context of these pathologies.

Scientific Objectives


Chronic inflammatory and neuro-inflammatory diseases are characterized by a dysregulated and imbalanced immune system. Among all immune cells, myeloid cells emerge as important players in several inflammatory diseases because of their ability to promote inflammation and oxidative stress in addition to their skill to detect and mitigate pathogenic states. Our team is interested in microglia in the brain and in monocytes / macrophages in tissues that are also confronted with chronic local inflammations such as: bone, joint and the kidneys. Microglia and macrophages establish interactions with neighboring tissue cells (by releasing mediators or not), and influence their activities not only under pathological conditions, but also under physiological conditions, especially during development, homeostatic tissue processes, tissue repair, and immunity. Playing major roles in the initiation and propagation of the chronic inflammation including neuro-inflammation, microglia as well as monocytes / macrophages are therefore relevant therapeutic targets.

Our research interests are focused on the pathophysiology of inflammatory and neuro-inflammatory disorders, and on the design and the development of new biotherapies and their implementation at the preclinical and clinical steps.

 

 

 

 

 

 

 

 

 


Axis 1: Pathophysiology and gene therapy for Sanfilippo syndrome, a paediatric neurodegenerative disease

Sanfilippo syndrome (also referred as Mucopolysaccharidosis IIIB) is characterized by severe neuro-inflammation and neurodegeneration caused by the deficiency of a lysosomal exoglycanase leading to the interruption of heparan sulfate (HS) degradation. The progressive accumulation of HS Oligosaccharides (HSOs) induces oxidative stress development, cytokine and chemokine production via a TLR4-dependent activation in the central nervous system (CNS) (Trudel, J Neurosci Res 2015) and in the osteoarticular system. The activation of TLR-4 induces microglial STAT3 signalling pathway activation leading to increase expression of hepcidin and brain iron retention (Puy, Glia 2018). We are currently studying the functional and molecular status of microglia in this syndrome. We are also elucidating the role of microglia in the initiation and the propagation of inflammation leading to the neurodegenerative processes in our models (murine BV2 and primary adult microglia, human CHME-5 microglia and Sanfilippo B mouse models). Microglia-derived extracellular vesicle (EVs) are suggested to be involved in propagation of inflammatory signals in brain. However, little is known about the biogenesis and the regulation of EVs production. Using biochemical and proteomic approaches, we aim at studying the production, composition and role of EVs produced by microglia during neuro-inflammation. There is currently no therapy for these diseases. In collaboration with teams from the Institut Pasteur and the APHP, we participated in a first phase I / II clinical trial of intracerebral gene therapy on 4 Sanfilippo B children, the results of which are very encouraging. However, the neurocognitive benefit was only partial, probably because the enzyme is not delivered to the periphery of the brain.

Our team is now launching a new preclinical study on animal models combining intracerebral and peripheral administration of a new vector crossing the blood brain barrier. If the results are convincing, a new clinical trial will be scheduled. This project is funded by the association Vaincre les Maladies Lysosomales.

Axis 2: Pathophysiology of Parkinson disease and new anti-inflammatory therapies for neurodegenerative diseases

“Reactive microgliosis” is now considered the causal agent of neuro-inflammation that leads to neurodegeneration in several diseases linked to ageing (among which Alzheimer’s Disease and Parkinson’s Disease, PD). Part of our research is to decipher the mechanisms and kinetics leading to “reactive microgliosis” in PD using mouse model thereof.
We are also designing new therapeutic approaches to treat chronic inflammation by targeting myeloid cells (monocytes/macrophages, dendritic cells, …). We have shown that immuno-modulatory phosphorus-based dendrimers such as the ABP dendrimer are able to switch the pro-inflammatory activation of monocytes/macrophages to an anti-inflammatory phenotype. We have proven the therapeutic efficacy of these molecules in several mouse models of chronic inflammatory diseases (Rheumatoid Arthritis, Multiple Sclerosis, …). Now we want to test the therapeutic efficacy of the ABP dendrimer (or of bio-active analogues) in mouse models of neurodegenerative diseases. The cellular and molecular mechanisms underpinning the therapeutic efficacy of the dendrimers, if any, will be delineated.
In parallel, we are collaborating with Michel Simon’s team at INFINITy to take advantage of the anti-inflammatory properties of phosphorus-based dendrimers to treat skin inflammatory diseases, and in particular psoriasis, by topical application of the dendrimers.

Axis 3. Iron metabolism and hepcidin in chronic inflammatory diseases

Iron that is present in all cells of the body, is necessary for life (oxygen transport, electron transfer reactions, or DNA synthesis). Physiological iron is used mainly to produce heme, the prosthetic group of hemoproteins such as hemoglobin, myoglobin and cytochrome P450. However, excess of iron represents a real threat for the cell since it is able to generate free radicals (ROS) during the Fenton reaction (chemical reaction using  iron and oxygenated water to produce hydroxyl radical: H2O2 + Fe2+ “OH + OH + Fe3+).  Iron is also incriminated to promote pathogen infection. In the body, iron balance is ensured by a strict equilibrium between its absorption from the diet and its storage by macrophages. Both intestinal absorption and macrophages release of iron are controlled by hepcidin, a small peptide synthesized and secreted by the liver. The expression of hepcidin is regulated by iron variations in the body (induced in iron overload and repressed by iron deficiency and stimulated erythropoiesis). In addition, being an acute phase protein, hepcidin in induced by inflammation, which in pathology contributes to functional iron deficiency and anemia of inflammation. Hepcidin is also expressed in many other organs, albeit at a much lower level (Kidney, brain, bone, monocytes/macrophages).

 

The main goal of this axis is to develop research leading to elucidate the role of extrahepatic hepcidin in infection/inflammation process and in pathologies facing oxidative stress due to the uncontrolled inflammatory iron accumulation both in mouse models and in patients. Currently, our priorities is kidney diseases (anemia of inflammation, urinary tract infection), neuroinflammation (Sanfilippo syndrome) and bone/joint (Rheumatic disease).

Axis 4: Bone remodeling, arthritis and therapeutics

Myeloid cells (monocytes, dendritic cells, macrophages and osteoclasts) play a central role in the pathogenesis of inflammatory osteo-articular diseases such as Rheumatoid Arthritis or Psoriatic Arthritis. They are notably involved in joint inflammation, structural damage, and inflammation-induced osteoporosis. We aim at better characterizing the involvement of myeloid cells and at investigating the impact of disease-modifying anti-rheumatic drugs (DMARDs) on these cells in inflammatory rheumatic diseases.

Our strong connection to the Rheumatology department of Toulouse University Hospital and to the national Rheumatology network of University Hospitals allows an access to local (BIOTOUL) and national clinical databases and biobanks involving patients with Rheumatoid arthritis (ESPOIR cohort), Psoriatic Arthritis (APACHE cohort), Spondyloarthritis (DESIR cohort) and Systemic mastocytosis (CEREMAST).

 

Currently, we are investigating: 1)- the impact of DMARDs on macrophage polarization and osteoclastogenesis in the context of inflammatory osteo-articular diseases. 2)- the mechanisms of TNF reverse signalling induced by anti-TNF agents and its implication in clinical response to anti-TNF agents. 3)- the role of hepcidin in joint inflammation and bone remodelling during arthritis;

Axis 6 : AlterAG, a new pathway for the synthesis of the endocannabinoid 2-arachidonoylglycerol in infectious and inflammatory pathologies

The discovery of endocannabinoid system (ECS), as revealed through studies of the most potent psychotropic compound from Cannabis sativa, D-9-tetrahydrocannabinol (THC), has opened a novel area of pharmacology suggesting its therapeutic potential in various pathological conditions. The ECS consists of cannabinoid receptors, their endogenous ligands (endocannabinoids) and proteins controlling their synthesis and degradation. To date, two cannabinoid receptors (CB1 and CB2) have been identified. They are cell membrane receptors containing seven transmembrane domains and they belong to the G-protein-coupled receptors family. Their expression is tissue specific since CB1 is mainly located in the central nervous system while CB2 is mainly expressed in the immune system. The two receptors are activated by endogenous lipid mediators that are released « on demand » in response to diverse physiological and pathological stimuli. Cannabinoids have pleiotropic activities like anti-inflammatory, immunomodulatory and neuroprotective properties. We have discovered a new pathway for the synthesis of the main endocannabinoid, 2-arachidonoylglycerol (2-AG), the full agonist of both receptors. This involves the hydrolysis by a lysophospholipase C called GDE3 (GDPD2 gene) of lysophosphatidylinositol (LPI), which is itself a ligand of a third type of endocannabinoid receptor (GPR55). GDE3 is expressed in particular in splenic red pulp fibroblasts, small intestine enterocytes, skin and a subpopulation of astrocytes.

Taking advantage of the use of mice invalidated for GDPD2 (GDE3-KO), we have shown a role of GDE3 in the defense against circulating bacteria, especially in the spleen. GDE3 could also contribute to neuro-inflammatory processes by intervening at two levels: small intestine, where it is essential for maintaining intestinal barrier integrity and microbiota balance, central nervous system, where it ensures the production of 2-AG on specific sites which remain to be identified.

The objective of this axis is to investigate the role of GDE3 and the mechanisms involved in several murine models of infectious and inflammatory pathologies of the gastrointestinal tract, brain (Experimental Autoimmune Encephalomyelitis or EAE, Parkinson’s disease and Sanfilippo syndrome), skin (psoriasis) and immune system. The involvement of the alternative pathway of 2-AG production, which we call Alter-AG, could thus provide interesting pharmacological targets to be explored in the context of these pathologies.

Axis 5 : Prader Willi Syndrome (PWS), neurodevelopment and epigenetics

Prader Willi Syndrome (PWS) is a rare neuro-developmental disease with a severe eating disorder and behavioral disturbances. We study PWS pathophysiology in the context of the National Reference Center for PWS, in Toulouse Children’s University Hospital coordinated by M. Tauber. We use complementary approaches with on-going clinical research studies and cellular models with iPSC (induced Pluripotent Stem Cells) from PWS patients. Some reports suggest an implication of SNORD116 in neuro-inflammation and neurodegeneration in PWS.

Specifically, we study the role of a small nucleolar RNA, SNORD116, with respect to neuroendocrine and endocrine abnormalities in PWS. Using specific hypothalamic neurons derived from iPSC of a patient with highly limited SNOD116 deletion (MD) (Am J Hum Genet, 2015) we have contributed to the demonstration of the role of SNORD116 in the processing of several prohormones (J Clin Invest, 2017; Coll. R. Liebel, Columbia Un. USA).

Our most recent results demonstrate the impact of SNORD116 and IGFBP7 on growth hormone therapy in PWS (Genet Med, 2021). Further studies are conducted in order to elucidate the molecular mechanisms involved.

A major topic is the role of hypothalamic dysfunction, especially related to ghrelin and oxytocin (OXT) pathways with therapeutics perspective as demonstrated by the beneficial effects of OXT administrated to PWS infants (Pediatrics, 2018 and Rev. in Lancet Diabetes Endocrinol, 2021). Ghrelin and OXT pathways in PWS in relation with SNORD116 deletion are also highly involved in addiction, food intake and behavioral disturbances, potentially linked to epigenetic modifications (Mol Psychiatry, 2020 and Transl Psychiatry, 2020).

A prospective study with placebo for the effect of OXT in infants is developed in the context of a European Trial PEDCRIN (OTBB3 Trial PedCRIN H2020 GA- N° 731046 4), supported by the startup OT4B. This study will be one support for clarifying the impact of SNORD116 and PWS on epigenetic processes in pathways underlying the dopaminergic circuit of recompense involved in addiction and social interaction (J. Salles, PhD thesis).

Another topic addresses the role of ghrelin disturbances and hormone resistance in bone metabolism. With respect to pathophysiology of scoliosis frequently observed in PWS, the molecular mechanism implicating cellular resistance are tested in models of osteoblasts (Biochim. Biophys. Acta, 2020 and Biochem Biophys Rep, 2020). This is connected with the Reference Center of the Metabolism of Calcium and Phosphate and ERN Bone coordinated by J.P. Salles.

Other details


Publications

2021

Tauber, Maith{é} ; Hoybye, Charlotte

Endocrine disorders in Prader-Willi syndrome: a model to understand and treat hypothalamic dysfunction Journal Article

The Lancet Diabetes and Endocrinology, 9 (4), pp. 235–246, 2021, ISSN: 22138595.

Abstract | Links | BibTeX

Salles, Juliette ; Lacassagne, Emmanuelle ; Eddiry, Sanaa ; Franchitto, Nicolas ; Salles, Jean Pierre ; Tauber, Maith{é}

What can we learn from PWS and SNORD116 genes about the pathophysiology of addictive disorders? Journal Article

Molecular Psychiatry, 26 (1), pp. 51–59, 2021, ISSN: 14765578.

Abstract | Links | BibTeX