Project acronym APOLs
Project Role of Apolipoproteins L in immunity and disease
Researcher (PI) Etienne Pays
Host Institution (HI) UNIVERSITE LIBRE DE BRUXELLES
Call Details Advanced Grant (AdG), LS6, ERC-2014-ADG
Summary Work conducted in my laboratory on the trypanosome killing factor of human serum led to the identification
of the primate-specific Apolipoprotein L1 (APOL1) as a novel pore-forming protein with striking similarities
with proteins of the apoptotic BCL2 family. APOL1 belongs to a family of proteins induced under
inflammatory conditions in myeloid and endothelial cells. APOL1 is efficiently neutralized by the SRA
protein of Trypanosoma rhodesiense, accounting for the ability of this trypanosome subspecies to infect
humans and cause sleeping sickness. We found that natural APOL1 variants escaping SRA neutralization and
therefore conferring human resistance to T. rhodesiense are associated with chronic kidney disease.
Moreover, transgenic mice expressing these APOL1 variants exhibit an obese phenotype. Our unpublished
results also indicate that APOLs control the lifespan of dendritic cells and podocytes activated by viral
stimuli. Therefore, we propose that the pathology of APOL variants is due to their deregulated activity on the
control of the cellular lifespan in myeloid/endothelial cells activated by pathogen detection.
This project aims at characterizing (i) the molecular mechanism by which APOLs control the lifespan of
activated dendritic cells and podocytes, which has direct impact on innate immunity and inflammation, and
(ii) the mechanism by which APOL1 variants cause pathology. In addition, we plan to detail the
physiological function of APOLs by studying the phenotype of transgenic mice either expressing human
APOL1 (wild-type and variants) or devoid of APOL genes, which we have recently generated. Finally, we
propose to exploit the extraordinary potential of trypanosomes for antigenic variation in order to produce
SRA variants able to neutralize the pathogenic APOL1 variants. Preliminary experiments suggest that in
podocytes SRA antagonizes APOL1 induction by viral stimulus and subsequent cell death, opening new
perspectives to treat kidney disease.
Summary
Work conducted in my laboratory on the trypanosome killing factor of human serum led to the identification
of the primate-specific Apolipoprotein L1 (APOL1) as a novel pore-forming protein with striking similarities
with proteins of the apoptotic BCL2 family. APOL1 belongs to a family of proteins induced under
inflammatory conditions in myeloid and endothelial cells. APOL1 is efficiently neutralized by the SRA
protein of Trypanosoma rhodesiense, accounting for the ability of this trypanosome subspecies to infect
humans and cause sleeping sickness. We found that natural APOL1 variants escaping SRA neutralization and
therefore conferring human resistance to T. rhodesiense are associated with chronic kidney disease.
Moreover, transgenic mice expressing these APOL1 variants exhibit an obese phenotype. Our unpublished
results also indicate that APOLs control the lifespan of dendritic cells and podocytes activated by viral
stimuli. Therefore, we propose that the pathology of APOL variants is due to their deregulated activity on the
control of the cellular lifespan in myeloid/endothelial cells activated by pathogen detection.
This project aims at characterizing (i) the molecular mechanism by which APOLs control the lifespan of
activated dendritic cells and podocytes, which has direct impact on innate immunity and inflammation, and
(ii) the mechanism by which APOL1 variants cause pathology. In addition, we plan to detail the
physiological function of APOLs by studying the phenotype of transgenic mice either expressing human
APOL1 (wild-type and variants) or devoid of APOL genes, which we have recently generated. Finally, we
propose to exploit the extraordinary potential of trypanosomes for antigenic variation in order to produce
SRA variants able to neutralize the pathogenic APOL1 variants. Preliminary experiments suggest that in
podocytes SRA antagonizes APOL1 induction by viral stimulus and subsequent cell death, opening new
perspectives to treat kidney disease.
Max ERC Funding
2 250 000 €
Duration
Start date: 2015-09-01, End date: 2020-08-31
Project acronym ASTHMACRYSTALCLEAR
Project Role of protein crystallization in type 2 immunity and asthma
Researcher (PI) Bart LAMBRECHT
Host Institution (HI) VIB
Call Details Advanced Grant (AdG), LS6, ERC-2017-ADG
Summary Spontaneous protein crystallization is a rare event in biology. Eosinophilic inflammation such as seen in the airways in asthma, chronic rhinosinusitis and helminth infection is however accompanied by accumulation of large amounts of extracellular Charcot-Leyden crystals. These are made of Galectin-10, a protein of unknown function produced by eosinophils, hallmark cells of type 2 immunity. In mice, eosinophilic inflammation is also accompanied by protein crystal build up, composed of the chitinase-like proteins Ym1 and Ym2, produced by alternatively activated macrophages. Here we challenge the current view that these crystals are just markers of eosinophil demise or macrophages activation. We hypothesize that protein crystallization serves an active role in immunoregulation of type 2 immunity. On the one hand, crystallization might turn a harmless protein into a danger signal. On the other hand, crystallization might sequester and eliminate the physiological function of soluble Galectin-10 and Ym1, or prolong it via slow release elution. For full understanding, we therefore need to understand the function of the proteins in a soluble and crystalline state. Our program at the frontline of immunology, molecular structural biology and clinical science combines innovative tool creation and integrative research to investigate the structure, function, and physiology of galectin-10 and related protein crystals. We chose to study asthma as the crystallizing proteins are abundantly present in human and murine disease. There is still a large medical need for novel therapies that could benefit patients with chronic steroid-resistant disease, and are alternatives to eosinophil-depleting antibodies whose long term effects are unknown.
Summary
Spontaneous protein crystallization is a rare event in biology. Eosinophilic inflammation such as seen in the airways in asthma, chronic rhinosinusitis and helminth infection is however accompanied by accumulation of large amounts of extracellular Charcot-Leyden crystals. These are made of Galectin-10, a protein of unknown function produced by eosinophils, hallmark cells of type 2 immunity. In mice, eosinophilic inflammation is also accompanied by protein crystal build up, composed of the chitinase-like proteins Ym1 and Ym2, produced by alternatively activated macrophages. Here we challenge the current view that these crystals are just markers of eosinophil demise or macrophages activation. We hypothesize that protein crystallization serves an active role in immunoregulation of type 2 immunity. On the one hand, crystallization might turn a harmless protein into a danger signal. On the other hand, crystallization might sequester and eliminate the physiological function of soluble Galectin-10 and Ym1, or prolong it via slow release elution. For full understanding, we therefore need to understand the function of the proteins in a soluble and crystalline state. Our program at the frontline of immunology, molecular structural biology and clinical science combines innovative tool creation and integrative research to investigate the structure, function, and physiology of galectin-10 and related protein crystals. We chose to study asthma as the crystallizing proteins are abundantly present in human and murine disease. There is still a large medical need for novel therapies that could benefit patients with chronic steroid-resistant disease, and are alternatives to eosinophil-depleting antibodies whose long term effects are unknown.
Max ERC Funding
2 499 846 €
Duration
Start date: 2018-08-01, End date: 2023-07-31
Project acronym CAPCAN
Project Molecular and Genetic Study of the human infections by Capnocytophaga canimorsus
Researcher (PI) Guy Richard Cornelis
Host Institution (HI) UNIVERSITE DE NAMUR ASBL
Call Details Advanced Grant (AdG), LS6, ERC-2011-ADG_20110310
Summary "Capnocytophaga canimorsus are Gram-negative bacteria from the normal oral flora of dogs, which cause rare but severe infections in humans that have been bitten or simply licked. The most common syndrome is fulminant septicemia with peripheral gangrene. Mortality reaches 40 % in spite of antibiotherapy and amputations. My laboratory pioneered recently the study of this new pathogen. We engineered genetic tools, sequenced and annotated the genome and determined the surface proteome of a strain isolated from a fatal infection. This showed that C. canimorsus have abundant surface-exposed lipoproteins forming a new kind of feeding complexes, some of them specialized in deglycosylating glycoproteins from the host. This property allows C. canimorsus to feed by grazing oligosaccharides at the surface of human cells. The present research program aims at characterizing these deglycosylating complexes, unravelling their role in neutralizing the innate immunity and promoting growth within the host and finally characterizing their assembly at the bacterial surface. Genomic comparisons will help defining which of these many complexes play a critical role in human pathogenesis. Besides this, the lipopolysaccharide structure will be determined and genetically manipulated to understand its low endotoxicity and small anti-inflammatory effectors present in the culture supernatant of C. canimorsus will be identified. Growth in human blood of wild type and mutant strains will be monitored by isothermal microcalorimetry in the hope of developing a surrogate of animal model. Such a ""virulence"" model would allow to address the question whether all dog's strains are equally dangerous for humans. It would also open an avenue for testing differences in individual human susceptibility. All this knowledge will give new insights in this emerging pathogen and might lead to prevention of the disease caused by C. canimorsus"
Summary
"Capnocytophaga canimorsus are Gram-negative bacteria from the normal oral flora of dogs, which cause rare but severe infections in humans that have been bitten or simply licked. The most common syndrome is fulminant septicemia with peripheral gangrene. Mortality reaches 40 % in spite of antibiotherapy and amputations. My laboratory pioneered recently the study of this new pathogen. We engineered genetic tools, sequenced and annotated the genome and determined the surface proteome of a strain isolated from a fatal infection. This showed that C. canimorsus have abundant surface-exposed lipoproteins forming a new kind of feeding complexes, some of them specialized in deglycosylating glycoproteins from the host. This property allows C. canimorsus to feed by grazing oligosaccharides at the surface of human cells. The present research program aims at characterizing these deglycosylating complexes, unravelling their role in neutralizing the innate immunity and promoting growth within the host and finally characterizing their assembly at the bacterial surface. Genomic comparisons will help defining which of these many complexes play a critical role in human pathogenesis. Besides this, the lipopolysaccharide structure will be determined and genetically manipulated to understand its low endotoxicity and small anti-inflammatory effectors present in the culture supernatant of C. canimorsus will be identified. Growth in human blood of wild type and mutant strains will be monitored by isothermal microcalorimetry in the hope of developing a surrogate of animal model. Such a ""virulence"" model would allow to address the question whether all dog's strains are equally dangerous for humans. It would also open an avenue for testing differences in individual human susceptibility. All this knowledge will give new insights in this emerging pathogen and might lead to prevention of the disease caused by C. canimorsus"
Max ERC Funding
1 473 338 €
Duration
Start date: 2012-07-01, End date: 2016-06-30
