Heart failure due to dilated cardiomyopathy is frequently caused by myocarditis. However, the pat... more Heart failure due to dilated cardiomyopathy is frequently caused by myocarditis. However, the pathogenesis of myocarditis remains incompletely understood. Here, we report the presence of neutrophil extracellular traps (NETs) in cardiac tissue of patients and mice with myocarditis. Inhibition of NET formation in experimental autoimmune myocarditis (EAM) of mice substantially reduces inflammation in the acute phase of the disease. Targeting the cytokine midkine (MK), which mediates NET formation in vitro, not only attenuates NET formation in vivo and the infiltration of polymorphonuclear neutrophils (PMNs) but also reduces fibrosis and preserves systolic function during EAM. Low-density lipoprotein receptor–related protein 1 (LRP1) acts as the functionally relevant receptor for MK-induced PMN recruitment as well as NET formation. In summary, NETosis substantially contributes to the pathogenesis of myocarditis and drives cardiac inflammation, probably via MK, which promotes PMN traffic...
Nearly 15 years after the first description of neutrophil extracellular traps (NETs), our knowled... more Nearly 15 years after the first description of neutrophil extracellular traps (NETs), our knowledge concerning this structure has expanded considerably. Initially, NETs were considered solely an elaborate function of the innate immune system to combat invading microorganisms. Successively it became clear that NETs have farther-reaching capabilities. They are involved in a series of pathophysiological mechanisms ranging from inflammation to thrombosis where they fulfill essential functions when produced at the right site and the right time but can have a serious impact when generation or clearance of NETs is inadequately controlled. This review provides a concise overview on the far-reaching functions of NETs in health and disease.
NETs contribute to malaria by promoting emergency granulopoiesis and endothelial binding of paras... more NETs contribute to malaria by promoting emergency granulopoiesis and endothelial binding of parasitized erythrocytes.
Neuregulins and their specific receptors, members of the ErbB family of tyrosine kinases, have be... more Neuregulins and their specific receptors, members of the ErbB family of tyrosine kinases, have been implicated in the control of growth and development of Schwann cells, specialized cells that wrap around nerve axons to provide electrical insulation. Here we use gene targeting to generate mice that lack ErbB3, a high-affinity neuregulin receptor. Homozygous erbB3 mutant embryos lack Schwann-cell precursors and Schwann cells that accompany peripheral axons of sensory and motor neurons. The initial development of motor neurons and sensory neurons of dorsal root ganglia occurs as it should, but at later stages most motor neurons (79%) and sensory neurons in dorsal root ganglia (82%) undergo cell death in erbB3 mutant embryos. Degeneration of the peripheral nervous system in erbB3 mutant pups is thus much more severe than the cell death in mice that lack neurotrophins or neurotrophin receptors. We also show that ErbB3 functions in a cell-autonomous way during the development of Schwann cells, but not in the survival of sensory or motor neurons. Our results indicate that sensory and motor neurons require factors for their survival that are provided by developing Schwann cells.
Plasmodium relies on actin-based motility to migrate from the site of infection and invade target... more Plasmodium relies on actin-based motility to migrate from the site of infection and invade target cells. Using a substrate-dependent gliding locomotion, sporozoites are able to move at fast speed (1–3 μm/s). This motility relies on a minimal set of actin regulatory proteins and occurs in the absence of detectable filamentous actin (F-actin). Here we report an overexpression strategy to investigate whether perturbations of F-actin steady-state levels affect gliding locomotion and host invasion. We selected two vital Plasmodium berghei G-actin–binding proteins, C-CAP and profilin, in combination with three stage-specific promoters and mapped the phenotypes afforded by overexpression in all three extracellular motile stages. We show that in merozoites and ookinetes, additional expression does not impair life cycle progression. In marked contrast, overexpression of C-CAP and profilin in sporozoites impairs circular gliding motility and salivary gland invasion. The propensity for product...
Proceedings of the National Academy of Sciences, 1995
The Ca(2+)-dependent cell adhesion molecule E-cadherin functions in the establishment and mainten... more The Ca(2+)-dependent cell adhesion molecule E-cadherin functions in the establishment and maintenance of epithelial cell morphology during embryogenesis and adulthood. Downregulation or complete shut-down of E-cadherin expression and mutation of the gene are observed during the progression of tumors of epithelial origin (carcinomas) and correlate with the metastatic potential. We have introduced a targeted mutation into the E-cadherin gene by homologous recombination in mouse embryonic stem cells. The mutation removes E-cadherin sequences essential for Ca2+ binding and for adhesive function. These embryonic stem cells were used to generate mice carrying the mutation. Heterozygous mutant animals appear normal and are fertile. However, the homozygous mutation is not compatible with life: E-cadherin -/- embryos show severe abnormalities before implantation. Particularly, the adhesive cells of the morula dissociate shortly after compaction has occurred, and their morphological polarizat...
Neuregulins (NDF, heregulin, GGF ARIA, or SMDF) are EGF-like growth and differentiation factors t... more Neuregulins (NDF, heregulin, GGF ARIA, or SMDF) are EGF-like growth and differentiation factors that signal through tyrosine kinase receptors of the ErbB family. Here, we report a novel phenotype in mice with targeted mutations in the erbB2, erbB3, orneuregulin-1 genes. These three mutations cause a severe hypoplasia of the primary sympathetic ganglion chain. We provide evidence that migration of neural crest cells to the mesenchyme lateral of the dorsal aorta, in which they differentiate into sympathetic neurons, depends on neuregulin-1 and its receptors. Neuregulin-1 is expressed at the origin of neural crest cells. Moreover, a tight link between neuregulin-1 expression, the migratory path, and the target site of sympathogenic neural crest cells is observed. Sympathetic ganglia synthesize catecholamines in the embryo and the adult. Accordingly, catecholamine levels in mutant embryos are severely decreased, and we suggest that the lack of catecholamines contributes to the embryonal...
Bacteriophages exert strong evolutionary pressure on their microbial hosts. In their lytic lifecy... more Bacteriophages exert strong evolutionary pressure on their microbial hosts. In their lytic lifecycle, complete bacterial subpopulations are utilized as hosts for bacteriophage replication. However, during their lysogenic lifecycle, bacteriophages can integrate into the host chromosome and alter the host’s genomic make-up, possibly resulting in evolutionary important adjustments. Not surprisingly, bacteria have evolved sophisticated immune systems to protect against phage infection. Streptococcus pyogenes isolates are frequently lysogenic and their prophages have been shown to be major contributors to the virulence of this pathogen. Most S. pyogenes phage research has focused on genomic prophages in relation to virulence, but little is known about the defensive arsenal of S. pyogenes against lytic phage infection. Here, we characterized Phage A1, an S. pyogenes bacteriophage, and investigated several mechanisms that S. pyogenes utilizes to protect itself against phage predation. We s...
Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a global threat. The only ... more Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a global threat. The only approved vaccine against TB, Mycobacterium bovis bacillus Calmette-Guérin (BCG), provides insufficient protection and, being a live vaccine, can cause disseminated disease in immunocompromised individuals. Previously, we found that intradermal cDNA tattoo immunization with cDNA of tetanus toxoid fragment C domain 1 fused to cDNA of the fusion protein H56, comprising the Mtb antigens Ag85B, ESAT-6, and Rv2660c, induced antigen-specific CD8+ T cell responses in vivo. As cDNA tattoo immunization would be safer than a live vaccine in immunocompromised patients, we tested the protective efficacy of intradermal tattoo immunization against TB with H56 cDNA, as well as with H56_E, a construct optimized for epitope processing in a mouse model. As Mtb antigens can be used in combination with BCG to boost immune responses, we also tested the protective efficacy of heterologous prime-boost, using de...
The human gastric pathogen Helicobacter pylori occurs in two basic variants, either exhibiting a ... more The human gastric pathogen Helicobacter pylori occurs in two basic variants, either exhibiting a functional cagPAI-encoded type-4-secretion-system (T4SS) or not. Only a few cagPAI positive strains have been successfully adapted for long-term infection of mice, including the pre-mouse Sydney strain 1 (PMSS1). Here we confirm that PMSS1 induces gastric inflammation and neutrophil infiltration in mice, progressing to intestinal metaplasia. Complete genome analysis of PMSS1 revealed 1,423 coding sequences, encompassing the cagPAI gene cluster and, unusually, location of the cytotoxin-associated gene A (cagA) approximately 15 kb downstream of the island. PMSS1 harbours three genetically exchangeable loci that are occupied by hopQ coding sequences. HopQ represents a critical co-factor required for translocation of CagA translocation into the host cell and activation of NF-κB by via the T4SS. Long-term colonization of mice led to an impairment of cagPAI functionality. One of the bacterial ...
Finegoldia magna, a Gram-positive anaerobic coccus, is an opportunistic pathogen, associated with... more Finegoldia magna, a Gram-positive anaerobic coccus, is an opportunistic pathogen, associated with medical device-related infections. F. magna is the only described species of the genus Finegoldia. We report the analysis of 17 genomes of Finegoldia isolates. Phylogenomic analyses showed that the Finegoldia population can be divided into two distinct clades, with an average nucleotide identity of 90.7%. One clade contains strains of F. magna, whereas the other clade includes more heterogeneous strains, hereafter tentatively named "Finegoldia nericia". The latter species appears to be more abundant in the human microbiome. Surface structure differences between strains of F. magna and "F. nericia" were detected by microscopy. Strain-specific heterogeneity is high and previously identified host-interacting factors are present only in subsets of "F. nericia" and F. magna strains. However, all genomes encode multiple host factor-binding proteins such as albumi...
Mycobacterium tuberculosis (Mtb) primarily resides in the lung but can also persist in extrapulmo... more Mycobacterium tuberculosis (Mtb) primarily resides in the lung but can also persist in extrapulmonary sites. Macrophages are considered the prime cellular habitat in all tissues. Here we demonstrate that Mtb resides inside adipocytes of fat tissue where it expresses stress-related genes. Moreover, perigonadal fat of Mtb-infected mice disseminated the infection when transferred to uninfected animals. Adipose tissue harbors leukocytes in addition to adipocytes and other cell types and we observed that Mtb infection induces changes in adipose tissue biology depending on stage of infection. Mice infected via aerosol showed infiltration of inducible nitric oxide synthase (iNOS) or arginase 1 (Arg1)-negative F4/80+ cells, despite recruitment of CD3+, CD4+ and CD8+ T cells. Gene expression analysis of adipose tissue of aerosol Mtb-infected mice provided evidence for upregulated expression of genes associated with T cells and NK cells at 28 days post-infection. Strikingly, IFN-γ-producing N...
Neutrophils are essential for immune defense and can respond to infection by releasing chromatin ... more Neutrophils are essential for immune defense and can respond to infection by releasing chromatin in the form of neutrophil extracellular traps (NETs). Here we show that NETs are induced by mitogens and accompanied by induction of cell-cycle markers, including phosphorylation of the retinoblastoma protein and lamins, nuclear envelope breakdown, and duplication of centrosomes. We identify cyclin-dependent kinases 4 and 6 (CDK4/6) as essential regulators of NETs and show that the response is inhibited by the cell-cycle inhibitor p21(Cip). CDK6, in neutrophils, is required for clearance of the fungal pathogen Candida albicans. Our data describe a function for CDK4/6 in immunity.
Malaria is a human parasitic disease that is transmitted by a mosquito vector. Plasmodium parasit... more Malaria is a human parasitic disease that is transmitted by a mosquito vector. Plasmodium parasites, the causative agents, differ in their infectivity and virulence to the mammalian host, but the mechanistic underpinnings of this variation remain unknown. As mosquitoes provide a nutrient-rich niche for development of transmissible stages, we examined the role of lipids in parasite development and infectivity by disrupting lipid trafficking in mosquito adults. We show that depleting the major mosquito lipoprotein lipophorin deprives parasites of neutral lipids, arrests oocysts growth and impairs sporozoite formation. Importantly, lipid deficiency decreases parasite mitochondrial membrane potential and severely compromises sporozoite infectivity and virulence in the mammalian host. Our findings demonstrate the requirement of mosquito lipids for Plasmodium metabolism, and uncover the mitochondrial contribution to parasite infectivity and virulence. By drawing a connection between vecto...
Heart failure due to dilated cardiomyopathy is frequently caused by myocarditis. However, the pat... more Heart failure due to dilated cardiomyopathy is frequently caused by myocarditis. However, the pathogenesis of myocarditis remains incompletely understood. Here, we report the presence of neutrophil extracellular traps (NETs) in cardiac tissue of patients and mice with myocarditis. Inhibition of NET formation in experimental autoimmune myocarditis (EAM) of mice substantially reduces inflammation in the acute phase of the disease. Targeting the cytokine midkine (MK), which mediates NET formation in vitro, not only attenuates NET formation in vivo and the infiltration of polymorphonuclear neutrophils (PMNs) but also reduces fibrosis and preserves systolic function during EAM. Low-density lipoprotein receptor–related protein 1 (LRP1) acts as the functionally relevant receptor for MK-induced PMN recruitment as well as NET formation. In summary, NETosis substantially contributes to the pathogenesis of myocarditis and drives cardiac inflammation, probably via MK, which promotes PMN traffic...
Nearly 15 years after the first description of neutrophil extracellular traps (NETs), our knowled... more Nearly 15 years after the first description of neutrophil extracellular traps (NETs), our knowledge concerning this structure has expanded considerably. Initially, NETs were considered solely an elaborate function of the innate immune system to combat invading microorganisms. Successively it became clear that NETs have farther-reaching capabilities. They are involved in a series of pathophysiological mechanisms ranging from inflammation to thrombosis where they fulfill essential functions when produced at the right site and the right time but can have a serious impact when generation or clearance of NETs is inadequately controlled. This review provides a concise overview on the far-reaching functions of NETs in health and disease.
NETs contribute to malaria by promoting emergency granulopoiesis and endothelial binding of paras... more NETs contribute to malaria by promoting emergency granulopoiesis and endothelial binding of parasitized erythrocytes.
Neuregulins and their specific receptors, members of the ErbB family of tyrosine kinases, have be... more Neuregulins and their specific receptors, members of the ErbB family of tyrosine kinases, have been implicated in the control of growth and development of Schwann cells, specialized cells that wrap around nerve axons to provide electrical insulation. Here we use gene targeting to generate mice that lack ErbB3, a high-affinity neuregulin receptor. Homozygous erbB3 mutant embryos lack Schwann-cell precursors and Schwann cells that accompany peripheral axons of sensory and motor neurons. The initial development of motor neurons and sensory neurons of dorsal root ganglia occurs as it should, but at later stages most motor neurons (79%) and sensory neurons in dorsal root ganglia (82%) undergo cell death in erbB3 mutant embryos. Degeneration of the peripheral nervous system in erbB3 mutant pups is thus much more severe than the cell death in mice that lack neurotrophins or neurotrophin receptors. We also show that ErbB3 functions in a cell-autonomous way during the development of Schwann cells, but not in the survival of sensory or motor neurons. Our results indicate that sensory and motor neurons require factors for their survival that are provided by developing Schwann cells.
Plasmodium relies on actin-based motility to migrate from the site of infection and invade target... more Plasmodium relies on actin-based motility to migrate from the site of infection and invade target cells. Using a substrate-dependent gliding locomotion, sporozoites are able to move at fast speed (1–3 μm/s). This motility relies on a minimal set of actin regulatory proteins and occurs in the absence of detectable filamentous actin (F-actin). Here we report an overexpression strategy to investigate whether perturbations of F-actin steady-state levels affect gliding locomotion and host invasion. We selected two vital Plasmodium berghei G-actin–binding proteins, C-CAP and profilin, in combination with three stage-specific promoters and mapped the phenotypes afforded by overexpression in all three extracellular motile stages. We show that in merozoites and ookinetes, additional expression does not impair life cycle progression. In marked contrast, overexpression of C-CAP and profilin in sporozoites impairs circular gliding motility and salivary gland invasion. The propensity for product...
Proceedings of the National Academy of Sciences, 1995
The Ca(2+)-dependent cell adhesion molecule E-cadherin functions in the establishment and mainten... more The Ca(2+)-dependent cell adhesion molecule E-cadherin functions in the establishment and maintenance of epithelial cell morphology during embryogenesis and adulthood. Downregulation or complete shut-down of E-cadherin expression and mutation of the gene are observed during the progression of tumors of epithelial origin (carcinomas) and correlate with the metastatic potential. We have introduced a targeted mutation into the E-cadherin gene by homologous recombination in mouse embryonic stem cells. The mutation removes E-cadherin sequences essential for Ca2+ binding and for adhesive function. These embryonic stem cells were used to generate mice carrying the mutation. Heterozygous mutant animals appear normal and are fertile. However, the homozygous mutation is not compatible with life: E-cadherin -/- embryos show severe abnormalities before implantation. Particularly, the adhesive cells of the morula dissociate shortly after compaction has occurred, and their morphological polarizat...
Neuregulins (NDF, heregulin, GGF ARIA, or SMDF) are EGF-like growth and differentiation factors t... more Neuregulins (NDF, heregulin, GGF ARIA, or SMDF) are EGF-like growth and differentiation factors that signal through tyrosine kinase receptors of the ErbB family. Here, we report a novel phenotype in mice with targeted mutations in the erbB2, erbB3, orneuregulin-1 genes. These three mutations cause a severe hypoplasia of the primary sympathetic ganglion chain. We provide evidence that migration of neural crest cells to the mesenchyme lateral of the dorsal aorta, in which they differentiate into sympathetic neurons, depends on neuregulin-1 and its receptors. Neuregulin-1 is expressed at the origin of neural crest cells. Moreover, a tight link between neuregulin-1 expression, the migratory path, and the target site of sympathogenic neural crest cells is observed. Sympathetic ganglia synthesize catecholamines in the embryo and the adult. Accordingly, catecholamine levels in mutant embryos are severely decreased, and we suggest that the lack of catecholamines contributes to the embryonal...
Bacteriophages exert strong evolutionary pressure on their microbial hosts. In their lytic lifecy... more Bacteriophages exert strong evolutionary pressure on their microbial hosts. In their lytic lifecycle, complete bacterial subpopulations are utilized as hosts for bacteriophage replication. However, during their lysogenic lifecycle, bacteriophages can integrate into the host chromosome and alter the host’s genomic make-up, possibly resulting in evolutionary important adjustments. Not surprisingly, bacteria have evolved sophisticated immune systems to protect against phage infection. Streptococcus pyogenes isolates are frequently lysogenic and their prophages have been shown to be major contributors to the virulence of this pathogen. Most S. pyogenes phage research has focused on genomic prophages in relation to virulence, but little is known about the defensive arsenal of S. pyogenes against lytic phage infection. Here, we characterized Phage A1, an S. pyogenes bacteriophage, and investigated several mechanisms that S. pyogenes utilizes to protect itself against phage predation. We s...
Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a global threat. The only ... more Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a global threat. The only approved vaccine against TB, Mycobacterium bovis bacillus Calmette-Guérin (BCG), provides insufficient protection and, being a live vaccine, can cause disseminated disease in immunocompromised individuals. Previously, we found that intradermal cDNA tattoo immunization with cDNA of tetanus toxoid fragment C domain 1 fused to cDNA of the fusion protein H56, comprising the Mtb antigens Ag85B, ESAT-6, and Rv2660c, induced antigen-specific CD8+ T cell responses in vivo. As cDNA tattoo immunization would be safer than a live vaccine in immunocompromised patients, we tested the protective efficacy of intradermal tattoo immunization against TB with H56 cDNA, as well as with H56_E, a construct optimized for epitope processing in a mouse model. As Mtb antigens can be used in combination with BCG to boost immune responses, we also tested the protective efficacy of heterologous prime-boost, using de...
The human gastric pathogen Helicobacter pylori occurs in two basic variants, either exhibiting a ... more The human gastric pathogen Helicobacter pylori occurs in two basic variants, either exhibiting a functional cagPAI-encoded type-4-secretion-system (T4SS) or not. Only a few cagPAI positive strains have been successfully adapted for long-term infection of mice, including the pre-mouse Sydney strain 1 (PMSS1). Here we confirm that PMSS1 induces gastric inflammation and neutrophil infiltration in mice, progressing to intestinal metaplasia. Complete genome analysis of PMSS1 revealed 1,423 coding sequences, encompassing the cagPAI gene cluster and, unusually, location of the cytotoxin-associated gene A (cagA) approximately 15 kb downstream of the island. PMSS1 harbours three genetically exchangeable loci that are occupied by hopQ coding sequences. HopQ represents a critical co-factor required for translocation of CagA translocation into the host cell and activation of NF-κB by via the T4SS. Long-term colonization of mice led to an impairment of cagPAI functionality. One of the bacterial ...
Finegoldia magna, a Gram-positive anaerobic coccus, is an opportunistic pathogen, associated with... more Finegoldia magna, a Gram-positive anaerobic coccus, is an opportunistic pathogen, associated with medical device-related infections. F. magna is the only described species of the genus Finegoldia. We report the analysis of 17 genomes of Finegoldia isolates. Phylogenomic analyses showed that the Finegoldia population can be divided into two distinct clades, with an average nucleotide identity of 90.7%. One clade contains strains of F. magna, whereas the other clade includes more heterogeneous strains, hereafter tentatively named "Finegoldia nericia". The latter species appears to be more abundant in the human microbiome. Surface structure differences between strains of F. magna and "F. nericia" were detected by microscopy. Strain-specific heterogeneity is high and previously identified host-interacting factors are present only in subsets of "F. nericia" and F. magna strains. However, all genomes encode multiple host factor-binding proteins such as albumi...
Mycobacterium tuberculosis (Mtb) primarily resides in the lung but can also persist in extrapulmo... more Mycobacterium tuberculosis (Mtb) primarily resides in the lung but can also persist in extrapulmonary sites. Macrophages are considered the prime cellular habitat in all tissues. Here we demonstrate that Mtb resides inside adipocytes of fat tissue where it expresses stress-related genes. Moreover, perigonadal fat of Mtb-infected mice disseminated the infection when transferred to uninfected animals. Adipose tissue harbors leukocytes in addition to adipocytes and other cell types and we observed that Mtb infection induces changes in adipose tissue biology depending on stage of infection. Mice infected via aerosol showed infiltration of inducible nitric oxide synthase (iNOS) or arginase 1 (Arg1)-negative F4/80+ cells, despite recruitment of CD3+, CD4+ and CD8+ T cells. Gene expression analysis of adipose tissue of aerosol Mtb-infected mice provided evidence for upregulated expression of genes associated with T cells and NK cells at 28 days post-infection. Strikingly, IFN-γ-producing N...
Neutrophils are essential for immune defense and can respond to infection by releasing chromatin ... more Neutrophils are essential for immune defense and can respond to infection by releasing chromatin in the form of neutrophil extracellular traps (NETs). Here we show that NETs are induced by mitogens and accompanied by induction of cell-cycle markers, including phosphorylation of the retinoblastoma protein and lamins, nuclear envelope breakdown, and duplication of centrosomes. We identify cyclin-dependent kinases 4 and 6 (CDK4/6) as essential regulators of NETs and show that the response is inhibited by the cell-cycle inhibitor p21(Cip). CDK6, in neutrophils, is required for clearance of the fungal pathogen Candida albicans. Our data describe a function for CDK4/6 in immunity.
Malaria is a human parasitic disease that is transmitted by a mosquito vector. Plasmodium parasit... more Malaria is a human parasitic disease that is transmitted by a mosquito vector. Plasmodium parasites, the causative agents, differ in their infectivity and virulence to the mammalian host, but the mechanistic underpinnings of this variation remain unknown. As mosquitoes provide a nutrient-rich niche for development of transmissible stages, we examined the role of lipids in parasite development and infectivity by disrupting lipid trafficking in mosquito adults. We show that depleting the major mosquito lipoprotein lipophorin deprives parasites of neutral lipids, arrests oocysts growth and impairs sporozoite formation. Importantly, lipid deficiency decreases parasite mitochondrial membrane potential and severely compromises sporozoite infectivity and virulence in the mammalian host. Our findings demonstrate the requirement of mosquito lipids for Plasmodium metabolism, and uncover the mitochondrial contribution to parasite infectivity and virulence. By drawing a connection between vecto...
Uploads