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 Our unpublished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 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
