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ObjectiveEpigenetic mechanisms, including DNA methylation (DNAm), have been proposed to play a key role in Crohn’s disease (CD) pathogenesis. However, the specific cell types and pathways affected as well as their potential impact on disease phenotype and outcome remain unknown. We set out to investigate the role of intestinal epithelial DNAm in CD pathogenesis.DesignWe generated 312 intestinal epithelial organoids (IEOs) from mucosal biopsies of 168 patients with CD (n=72), UC (n=23) and healthy controls (n=73). We performed genome-wide molecular profiling including DNAm, bulk as well as single-cell RNA sequencing. Organoids were subjected to gene editing and the functional consequences of DNAm changes evaluated using an organoid-lymphocyte coculture and a nucleotide-binding oligomerisation domain, leucine-rich repeat and CARD domain containing 5 (NLRC5) dextran sulphate sodium (DSS) colitis knock-out mouse model.ResultsWe identified highly stable, CD-associated loss of DNAm at major histocompatibility complex (MHC) class 1 loci including NLRC5and cognate gene upregulation. Single-cell RNA sequencing of primary mucosal tissue and IEOs confirmed the role of NLRC5 as transcriptional transactivator in the intestinal epithelium. Increased mucosal MHC-I and NLRC5 expression in adult and paediatric patients with CD was validated in additional cohorts and the functional role of MHC-I highlighted by demonstrating a relative protection from DSS-mediated mucosal inflammation in NLRC5-deficient mice. MHC-I DNAm in IEOs showed a significant correlation with CD disease phenotype and outcomes. Application of machine learning approaches enabled the development of a disease prognostic epigenetic molecular signature.ConclusionsOur study has identified epigenetically regulated intestinal epithelial MHC-I as a novel mechanism in CD pathogenesis.

ABSTRACTThe influence of the owner family on managerial decision-making in family firms is undisputed. However, we know relatively little about how this influence is exerted. Based on upper echelon theory, and in the context of innovation management, we explore the owner family’s influence via collaborative dialogue. Quantitative analyses based on 116 family firms, substantiated by 12 qualitative interviews within seven family firms, show that an owner family’s collaborative dialogue minimizes the influence of an owner manager’s attitude toward risk on TMT innovativeness. On the other hand, the collaborative dialogue strengthens the impact TMT innovativeness has on firm-level innovative capacity.

The liver has been studied extensively due to the broad number of diseases affecting its vital functions. However, therapeutic advances have been hampered by the lack of knowledge concerning human hepatic development. Here, we addressed this limitation by describing the developmental trajectories of different cell types that make up the human liver at single-cell resolution. These transcriptomic analyses revealed that sequential cell-to-cell interactions direct functional maturation of hepatocytes, with non-parenchymal cells playing essential roles during organogenesis. We utilized this information to derive bipotential hepatoblast organoids and then exploited this model system to validate the importance of signalling pathways in hepatocyte and cholangiocyte specification. Further insights into hepatic maturation also enabled the identification of stage-specific transcription factors to improve the functionality of hepatocyte-like cells generated from human pluripotent stem cells. Thus, our study establishes a platform to investigate the basic mechanisms directing human liver development and to produce cell types for clinical applications.

Intestinal stem and progenitor cells replicate and differentiate in distinct compartments, influenced by Wnt, BMP, and other subepithelial cues. The cellular sources of these signals were long obscure because intestinal mesenchyme was insufficiently characterised. In this Review, we discuss how recent mRNA profiles of mouse and human intestinal submucosa, coupled with fine-resolution microscopy and gene and cell disruptions, reveal a coherent picture of an organised tissue carrying cells with distinct molecular properties and functions.

Research has started to investigate personality traits of social entrepreneurs because such traits in commercial entrepreneurs have been found to affect new venture creation/success. In this exploratory study, we apply the person‐environment fit theory and analyze specific social entrepreneurial personality dimensions (i.e., altruism, empathic concern, personal distress, compassion), and classical entrepreneurial personality dimensions (i.e., need for achievement (nAch), entrepreneurial self‐efficacy (ESE), general self‐efficacy, risk‐taking propensity) to identify differences between prospective social and commercial entrepreneurs. Using a sample of 85 prospective entrepreneurs, results show that prospective social entrepreneurs differ from prospective commercial entrepreneurs in the personality dimensions of personal distress, nAch, ESE, and risk‐taking propensity.

ObjectiveHuman intestinal epithelial organoids (IEOs) are increasingly being recognised as a highly promising translational research tool. However, our understanding of their epigenetic molecular characteristics and behaviour in culture remains limited.DesignWe performed genome-wide DNA methylation and transcriptomic profiling of human IEOs derived from paediatric/adult and fetal small and large bowel as well as matching purified human gut epithelium. Furthermore, organoids were subjected to in vitro differentiation and genome editing using CRISPR/Cas9 technology.ResultsWe discovered stable epigenetic signatures which define regional differences in gut epithelial function, including induction of segment-specific genes during cellular differentiation. Established DNA methylation profiles were independent of cellular environment since organoids retained their regional DNA methylation over prolonged culture periods. In contrast to paediatric and adult organoids, fetal gut-derived organoids showed distinct dynamic changes of DNA methylation and gene expression in culture, indicative of an in vitro maturation. By applying CRISPR/Cas9 genome editing to fetal organoids, we demonstrate that this process is partly regulated by TET1, an enzyme involved in the DNA demethylation process. Lastly, generating IEOs from a child diagnosed with gastric heterotopia revealed persistent and distinct disease-associated DNA methylation differences, highlighting the use of organoids as disease-specific research models.ConclusionsOur study demonstrates striking similarities of epigenetic signatures in mucosa-derived IEOs with matching primary epithelium. Moreover, these results suggest that intestinal stem cell-intrinsic DNA methylation patterns establish and maintain regional gut specification and are involved in early epithelial development and disease.

Spirochetes have developed sophisticated means to successfully colonize host tissues and survive in unfavorable environments. Attachment to human cells is thought to be a key step for the establishment of an infection that causes multiple clinical symptoms. Infection of host tissues largely depends on the ability of spirochetes to attach to different cell types. In this study, we examine the ability of spirochetes belonging to seven distinct genospecies (Borrelia (B.) burgdorferisensu stricto (s.s.), B. afzelii, B. garinii, B. spielmanii, B. bavariensis, B. lusitaniae,and B. valaisiana) to adhere to human keratinocytes. Among the genospecies analyzed, B. valaisianaand B. spielmaniishowed the strongest adherence while B. bavariensis, B. gariniiand B. afzeliidisplayed moderate binding activity. By contrast, only a few cells of B. burgdorferis.s. and B. lusitaniaebound to keratinocytes. Furthermore, intra-species differences have also been observed among B. garinii, B. bavariensis, B. afzelii, and in particular B. valaisiana.

ABSTRACTAcinetobacter baumanniiis a Gram-negative pathogen that causes a multitude of nosocomial infections. The Acinetobactertrimeric autotransporter adhesin (Ata) belongs to the superfamily of trimeric autotransporter adhesins which are important virulence factors in many Gram-negative species. Phylogenetic profiling revealed that atais present in 78% of all sequenced A. baumanniiisolates but only in 2% of the closely related species A. calcoaceticusand A. pittii. Employing a markerless atadeletion mutant of A. baumanniiATCC 19606 we show that adhesion to and invasion into human endothelial and epithelial cells depend on Ata. Infection of primary human umbilical cord vein endothelial cells (HUVECs) with A. baumanniiled to the secretion of interleukin (IL)-6 and IL-8 in a time- and Ata-dependent manner. Furthermore, infection of HUVECs by WT A. baumanniiwas associated with higher rates of apoptosis via activation of caspases-3 and caspase-7, but not necrosis, in comparison to ∆ata. Ata deletion mutants were furthermore attenuated in their ability to kill larvae of Galleria mellonellaand to survive in larvae when injected at sublethal doses. This indicates that Ata is an important multifunctional virulence factor in A. baumanniithat mediates adhesion and invasion, induces apoptosis and contributes to pathogenicity in vivo.

Signals from the surrounding niche drive proliferation and suppress differentiation of intestinal stem cells (ISCs) at the bottom of intestinal crypts. Among sub-epithelial support cells, deep sub-cryptal CD81+PDGFRAlotrophocytes capably sustain ISC functions ex vivo. Here, we show that mRNA and chromatin profiles of abundant CD81−PDGFRAlomouse stromal cells resemble those of trophocytes and that both populations provide crucial canonical Wnt ligands. Mesenchymal expression of key ISC-supportive factors extends along a spatial and molecular continuum from trophocytes into peri-cryptal CD81−CD55hicells, which mimic trophocyte activity in organoid co-cultures. Graded expression of essential niche factors is not cell-autonomous but dictated by the distance from bone morphogenetic protein (BMP)-secreting PDGFRAhimyofibroblast aggregates. BMP signaling inhibits ISC-trophic genes in PDGFRAlocells near high crypt tiers; that suppression is relieved in stromal cells near and below the crypt base, including trophocytes. Cell distances thus underlie a self-organized and polar ISC niche.

In North America, Lyme disease is primarily caused by the spirochetal bacterium Borrelia burgdorferisensu stricto (Bb), which is transmitted between multiple vertebrate hosts and ixodid ticks, and is a model commonly used to study host-pathogen interactions. While Bbis consistently observed in its mammalian and avian reservoirs, the bacterium is rarely isolated from North American reptiles. Two closely related lizard species, the eastern fence lizard (Sceloporus undulatus) and the western fence lizard (Sceloporus occidentalis), are examples of reptiles parasitized by Ixodesticks. Vertebrates are known to generate complement as an innate defense mechanism, which can be activated before Bbdisseminate to distal tissues. Complement from western fence lizards has proven lethal against one Bbstrain, implying the role of complement in making those lizards unable to serve as hosts to Bb. However, BbDNA is occasionally identified in distal tissues of field-collected eastern fence lizards, suggesting some Bbstrains may overcome complement-mediated clearance in these lizards. These findings raise questions regarding the role of complement and its impact on Bbinteractions with North American lizards. In this study, we found Bbseropositivity in a small population of wild-caught eastern fence lizards and observed Bbstrain-specific survivability in lizard sera. We also found that a Bbouter surface protein, OspE, from Bbstrains viable in sera, promotes lizard serum survivability and binds to a complement inhibitor, factor H, from eastern fence lizards. Our data thus identify bacterial and host determinants of eastern fence lizard complement evasion, providing insights into the role of complement influencing Bbinteractions with North American lizards.

Cell motility and biomechanics are critical in various (patho)physiological processes, including the regulation of vascular barrier integrity, which can be subverted by bacterial pathogens. Here, we present a protocol on how to expose endothelial cells (ECs) to vector-borne Borrelia burgdorferi(Bb) and characterize EC kinematics and dynamics during exposure to live or heat-inactivated Bbthrough traction force and monolayer stress microscopy. Modifications to this protocol may be necessary for studying how different cell types interact with Bbor other microorganisms.

DNA methylation is one of the major epigenetic mechanisms implicated in regulating cellular development and cell-type-specific gene expression. Here we performed simultaneous genome-wide DNA methylation and gene expression analysis on purified intestinal epithelial cells derived from human fetal gut, healthy pediatric biopsies, and children newly diagnosed with inflammatory bowel disease (IBD). Results were validated using pyrosequencing, real-time PCR, and immunostaining. The functional impact of DNA methylation changes on gene expression was assessed by employing in-vitroassays in intestinal cell lines. DNA methylation analyses allowed identification of 214 genes for which expression is regulated via DNA methylation, i.e. regulatory differentially methylated regions (rDMRs). Pathway and functional analysis of rDMRs suggested a critical role for DNA methylation in regulating gene expression and functional development of the human intestinal epithelium. Moreover, analysis performed on intestinal epithelium of children newly diagnosed with IBD revealed alterations in DNA methylation within genomic loci, which were found to overlap significantly with those undergoing methylation changes during intestinal development. Our study provides novel insights into the physiological role of DNA methylation in regulating functional maturation of the human intestinal epithelium. Moreover, we provide data linking developmentally acquired alterations in the DNA methylation profile to changes seen in pediatric IBD.

DNA methylation is one of the major epigenetic mechanisms implicated in regulating cellular development and cell-type-specific gene expression. Here we performed simultaneous genome-wide DNA methylation and gene expression analysis on purified intestinal epithelial cells derived from human fetal gut, healthy pediatric biopsies, and children newly diagnosed with inflammatory bowel disease (IBD). Results were validated using pyrosequencing, real-time PCR, and immunostaining. The functional impact of DNA methylation changes on gene expression was assessed by employing in-vitroassays in intestinal cell lines. DNA methylation analyses allowed identification of 214 genes for which expression is regulated via DNA methylation, i.e. regulatory differentially methylated regions (rDMRs). Pathway and functional analysis of rDMRs suggested a critical role for DNA methylation in regulating gene expression and functional development of the human intestinal epithelium. Moreover, analysis performed on intestinal epithelium of children newly diagnosed with IBD revealed alterations in DNA methylation within genomic loci, which were found to overlap significantly with those undergoing methylation changes during intestinal development. Our study provides novel insights into the physiological role of DNA methylation in regulating functional maturation of the human intestinal epithelium. Moreover, we provide data linking developmentally acquired alterations in the DNA methylation profile to changes seen in pediatric IBD.

Epigenetics can be defined as stable, potentially heritable changes in the cellular phenotype caused by mechanisms other than alterations to the underlying DNA sequence. As such, any observed phenotypic changes including organ development, aging, and the occurrence of disease could be driven by epigenetic mechanisms in the presence of stable cellular DNA sequences. Indeed, with the exception of rare mutations, the human genome-sequence has remained remarkably stable over the past centuries. In contrast, substantial changes to our environment as part of our modern life style have not only led to a significant reduction of certain infectious diseases but also seen the exponential increase in complex traits including obesity and multifactorial diseases such as autoimmune disorders. It is becoming increasingly clear that epigenetic mechanisms operate at the interface between the genetic code and our environment, and a large body of existing evidence supports the importance of environmental factors such as diet and nutrition, infections, and exposure to toxins on human health. This seems to be particularly the case during vulnerable periods of human development such as pregnancy and early life. Importantly, as the first point of contact for many of such environmental factors including nutrition, the digestive system is being increasingly linked to a number of “modern” pathologies. In this review article, we aim to give a brief introduction to the basic molecular principals of epigenetics and provide a concise summary of the existing evidence for the role of epigenetic mechanisms in gastrointestinal health and disease, hepatology, and nutrition.

Diese Studie untersucht die Auswirkungen von Herkunftslandinformationen von Produkten auf Qualitätswahrnehmungen, Einstellungen und Kaufabsichten von Konsumenten mittels einer differenzierten Metaanalyse, die insgesamt 67 Studien mit 327 Effektstärken integriert. Die Ergebnisse zeigen einen mittleren bis hohen signifikanten Country-of-Origin (COO)-Effekt. Nach der Globalisierungswelle zeigt sich ein verringerter COO-Effekt. Die differenzierte Betrachtung multidimensionaler Effekte zeigt einen vergleichsweise hohen Effekt des Country-of-Brand. Zusätzlich konnten zwei neue Moderatoren identifiziert werden. Erstens messen Studien, die auf Studentenstichproben basieren, höhere COO-Effekte. Zweitens fallen die Ergebnisse in Experimenten geringer aus, wenn hybride Produkte untersucht werden. This study applies a differentiated meta-analysis, which integrates 67 studies and 327 effect sizes, to analyze the impact of country-of-origin (COO) effects of products on quality perceptions, attitudes, and purchase intentions of customers. Results show a moderate to strong significant COO effect for the investigated period. This effect becomes weaker after the globalization wave after the period of the 1990s. The differentiated consideration of multidimensional effects shows a comparatively strong effect of the country-of-brand. Additionally, we identified two new moderators. First, studies that use student samples show stronger COO effects. Second, studies that use hybrid products show weaker COO effects.

•Borreliae in mosquitoes (Culicidae).•Supposed transstadial transmission.•Findings not restricted to a single host genus.•First evidence of mosquitoes infected by borreliae in Germany.

Borrelia miyamotoi, a relapsing fever spirochete transmitted by ixodid ticks, is able to cause infections associated with systemic complaints, including malaise and fever, as well as meningoencephalitis in immunocompromised patients. In order to elucidate immune evasion of previously difficult to cultivate B. miyamotoi, we have examined the ability of this newly emerging human pathogen to escape the complement system. Growth inhibition assays revealed that B. miyamotoiis strongly resistant to complement-mediated bacteriolysis. Investigating complement activation, we found that B. miyamotoishowed reduced deposition of components C3, C5, C7, C8, C9 as well as the membrane attack complex (MAC) on the borrelial surface. In addition, no aberrations in cell morphology were observed after incubation of B. miyamotoiin active human serum, confirming the findings of the growth inhibition assay. The data presented here provide strong evidence that B. miyamotoiovercome human complement by affecting the central complement component C3, thereby inhibiting formation of the C3 convertase and downstream activation of the complement cascade.

Diese Studie untersucht im Rahmen einer Metaanalyse den Zusammenhang zwischen dem training und dem Einsatzerfolg von Expatriates. Bisherige Metaanalysen zu diesem Thema haben mehrheitlich Studien mit einem Fokus auf Soldaten, Ärzten und Schülern berücksichtigt. Um weitere Erkenntnisse auf Unternehmensebene zu gewinnen, berücksichtigt diese Metananalyse 28 Studien, die alle einen Fokus auf Managern haben. Die Ergebnisse zeigen einen positiven und signifikanten Effekt von Training auf die Arbeitszufriedenheit und das Commitment von Expatriates. Weiterhin zeigen die Ergebnisse, dass Training die Abbruchabsicht von Expatriates verringert. Betrachtet man Anpassung als Erfolgskriterium, so besteht kein signifikanter Zusammenhang zwischen Training und Arbeits- und Interaktionsanpassung. Hinsichtlich der kulturellen Anpassung zeigen die Ergebnisse lediglich einen schwachen Zusammenhang. In order to prepare expatriates for assignments abroad, companies invest in expatriates training. Prior research on the effect of expatriate training on expatriate performance is inconsistent and has mostly focused on soldiers, medical doctors, and students. Hence, this study analyzes the relationship between expatriate training and expatriate performance on an organizational level by applying a meta-analysis including 28 studies with a focus on managers. Results show that expatriate training has a positive and significant effect on job satisfaction and commitment. Further, expatriate training decreases the intention of expatriates to leave the job. In contrast, applying facets of adjustment as performance indicator, results show no significant effect of expatriate training on work adjustment and interaction adjustment. The effect of expatriates training on cultural adjustment is marginal significant. The study discusses implications of the findings for research and management and develops avenues for future research.

ABSTRACTCspA of the Lyme disease spirochete Borrelia burgdorferirepresents a key molecule in immune evasion, protecting borrelial cells from complement-mediated killing. As previous studies focused almost exclusively on CspA of B. burgdorferi, here we investigate the different binding capacities of CspA orthologs of Borrelia burgdorferi, B. afzelii, and B. spielmaniifor complement regulator factor H and plasminogen and their ability to inhibit complement activation by either binding these host-derived plasma proteins or independently by direct interaction with components involved in formation of the lethal, pore-like terminal complement complex. To further examine their function in serum resistance in vivo, a serum-sensitive B. gariniistrain was used to generate spirochetes, ectopically producing functional CspA orthologs. Irrespective of their species origin, all three CspA orthologs impart resistance to complement-mediated killing when produced in a serum-sensitive B. gariniisurrogate strain. To analyze the inhibitory effect on complement activation and to assess the potential to inactivate C3b by binding of factor H and plasminogen, recombinant CspA orthologs were also investigated. All three CspA orthologs simultaneously bound factor H and plasminogen but differed in regard to their capacity to inactivate C3b via bound plasmin(ogen) and inhibit formation of the terminal complement complex. CspA of B. afzeliibinds plasmin(ogen) and inhibits the terminal complement complex more efficiently than CspA of B. burgdorferiand B. spielmanii. Taken together, CspA orthologs of serum-resistant Lyme disease spirochetes act as multifunctional evasion molecules that inhibit complement on two central activation levels, C3b generation and assembly of the terminal complement complex.

Tick-borne encephalitis (TBE) and Lyme borreliosis are the most common tick-borne zooanthroponoses in Germany. The federal risk map for TBE in this country is based on recorded cases of human infection, whereas information on the vector-based prevalence of either pathogen is fragmentary. In this study, a total of 12,497 host-seeking nymphal and adult Ixodes ricinusticks (Acari: Ixodidae) were collected from March to October 2009 and April to June 2010, in 5 TBE non-risk and 4 TBE risk areas of the Rhine-Main region (Hesse) via flagging. A total of 3615 ticks was examined for infection with Borrelia burgdorferisensu lato and 9115 ticks were analyzed for TBE virus (TBEV). Pathogens were detected by real-time polymerase chain reaction. Among 3615 questing ticks, 344 (9.5%) were found infected with B. burgdorferisensu lato. Five Borreliagenospecies were identified by sequencing the OspAgene: B. afzelii(81.3%), B. garinii(14.0%), B. valaisiana(2.7%), B. spielmanii(1.3%), and B. bavariensis(0.7%). TBE infection of ticks differed between areas classified as TBE risk and TBE non-risk areas. While the prevalence of TBEV was between 0 and 0.2% (3 of 3947 ticks) in the TBE risk areas, no TBEV-infected tick was detected from TBE non-risk areas. The results show that B. burgdorferisensu lato occurred in all 9 examined locations, indicating that Lyme borreliosis is prevalent in the Rhine-Main region, whereas TBEV was detected only in previously classified risk areas.

Borrelia burgdorferi, the etiological agent of Lyme disease, exploits an array of strategies to establish infection and to overcome host innate and adaptive immune responses. One key borrelial immune escape mechanism involves the inactivation of host complement attack through acquisition of human immune regulators factor H (CFH), factor H-like protein 1 (FHL1), factor H-related protein 1 (CFHR1), CFHR2, and/or CFHR5. Binding of these host proteins is primarily mediated by bacterial surface-exposed proteins that have been collectively referred to as complement regulator-acquiring surface proteins, or CRASPs. Different strains of B. burgdorferiproduce as many as 5 different CRASP molecules that comprise 3 distinct, genetically unrelated groups. Depending on bacterial genetic composition, different combinations of these proteins can be found on the borrelial outer surface. The 3 groups differ in their gene location, gene regulatory mechanisms, expression patterns during the tick-mammal infection cycle, protein sequence and structure as well as binding affinity for complement regulators and other serum proteins. These attributes influence the proteins’ abilities to contribute to complement resistance of this emerging human pathogen. In this review, we focus on the current knowledge on structure, function, and gene regulation of these B. burgdorferiinfection-associated proteins.

ABSTRACTSpirochetes belonging to the Borrelia burgdorferisensu lato complex differ in resistance to complement-mediated killing by human serum. Here, we characterize complement sensitivity of a panel of B. lusitaniaeisolates derived from ticks collected in Germany and Portugal as well as one patient-derived isolate, PoHL. All isolates are highly susceptible to complement-mediated lysis in human serum and activate complement predominantly by the alternative pathway, leading to an increased deposition of complement components C3, C6, and the terminal complement complex. Interestingly, serum-sensitive B. lusitaniaeisolates were able to bind immune regulator factor H (CFH), and some strains also bound CFH-related protein 1 (CFHR1) and CFHR2. Moreover, CFH bound to the surface of B. lusitaniaewas inefficient in mediating C3b conversion. Furthermore, the identification and characterization of a potential CFH-binding protein, OspE, revealed that this molecule possesses a significantly reduced binding capacity for CFH compared to that of CFH-binding OspE paralogs expressed by various serum-resistant Borreliaspecies. This finding suggests that a reduced binding capability of CFH is associated with an increased serum sensitivity of B. lusitaniaeto human complement.

Spirochetes belonging to the Borrelia burgdorferi sensu lato complex differ in resistance to complement-mediated killing by human serum. Here, we characterize complement sensitivity of a panel of B. lusitaniae isolates derived from ticks collected in Germany and Portugal as well as one patient-derived isolate, PoHL. All isolates are highly susceptible to complement-mediated lysis in human serum and activate complement predominantly by the alternative pathway, leading to an increased deposition of complement components C3, C6, and the terminal complement complex. Interestingly, serum-sensitive B. lusitaniae isolates were able to bind immune regulator factor H (CFH), and some strains also bound CFH-related protein 1 (CFHR1) and CFHR2. Moreover, CFH bound to the surface of B. lusitaniae was inefficient in mediating C3b conversion. Furthermore, the identification and characterization of a potential CFH-binding protein, OspE, revealed that this molecule possesses a significantly reduced binding capacity for CFH compared to that of CFH-binding OspE paralogs expressed by various serum-resistant Borrelia species. This finding suggests that a reduced binding capability of CFH is associated with an increased serum sensitivity of B. lusitaniae to human complement.

ABSTRACTIn North America, tick-borne relapsing fever is caused by the species Borrelia hermsii, B. parkeri, and B. turicatae, which are transmitted to humans through the bite of the respective infected tick vectors. Here we describe the identification and functional characterization of a surface lipoprotein of B. parkeri, designated BpcA, that binds the human complement regulators factor H and factor H-related protein 1 and, simultaneously, the host protease plasminogen. In contrast, the homologous B. turicataeprotein failed to bind human factor H and factor H-related protein 1 but retained its plasminogen binding capacity. Factor H bound to BpcA maintains its regulatory capacity to control C3b deposition and C3 convertase activity. Ectopic expression of BpcA in a serum-sensitive B. burgdorferistrain protects transformed cells from complement-mediated killing. Furthermore, bound plasminogen/plasmin endows B. parkeriand B. turicataewith the potential to degrade extracellular matrix components. These findings expand our understanding of the putative recent evolutionary separation of Borrelia parkeriand Borrelia turicatae, provide evidence that B. parkeridiffers from B. turicataein its ability to resist complement attack, and may help in understanding the pathological processes underlying tick-borne relapsing fever.

In North America, tick-borne relapsing fever is caused by the species Borrelia hermsii, B. parkeri, and B. turicatae, which are transmitted to humans through the bite of the respective infected tick vectors. Here we describe the identification and functional characterization of a surface lipoprotein of B. parkeri, designated BpcA, that binds the human complement regulators factor H and factor H-related protein 1 and, simultaneously, the host protease plasminogen. In contrast, the homologous B. turicatae protein failed to bind human factor H and factor H-related protein 1 but retained its plasminogen binding capacity. Factor H bound to BpcA maintains its regulatory capacity to control C3b deposition and C3 convertase activity. Ectopic expression of BpcA in a serum-sensitive B. burgdorferi strain protects transformed cells from complement-mediated killing. Furthermore, bound plasminogen/plasmin endows B. parkeri and B. turicatae with the potential to degrade extracellular matrix components. These findings expand our understanding of the putative recent evolutionary separation of Borrelia parkeri and Borrelia turicatae, provide evidence that B. parkeri differs from B. turicatae in its ability to resist complement attack, and may help in understanding the pathological processes underlying tick-borne relapsing fever.

Tigecycline is a new glycylcycline that has recently been revealed to be very effective in vitro against a variety of Gram-negative and Gram-positive bacteria including multi-drug resistant microorganisms. Using a standardized microdilution susceptibility testing method, we determined the minimal inhibitory concentrations (MICs) and the minimal bactericidal concentrations (MBCs) of tigecycline, in parallel with doxycycline, tetracycline, and other antibiotic agents relevant for Lyme borreliosis treatment such as ceftriaxone and cefotaxime. The activity of all agents against 16 different Borreliaisolates belonging to all borrelial genospecies known to be pathogenic for humans was investigated and analyzed under standardized conditions.

ABSTRACTPrevious studies using small numbers of serum samples from human patients and experimentally infected animals identified the frequent presence of antibodies recognizing RevA, a borrelial fibronectin-binding outer surface protein. We now demonstrate that most examined Lyme disease spirochetes from North America and Europe contain genes encoding RevA proteins, some with extensive regions of conservation and others with moderate diversity. Line blot analyses using recombinant RevA from two diverse Lyme disease spirochetes of RevA and serum samples from culture-confirmed human Lyme disease patients from the United States (n= 46, mainly with early Lyme disease) and Germany (>500, with early and late manifestations of Lyme disease) were performed. The results indicated that a sizable proportion of patients produced antibodies that recognized recombinant RevA. Overall, RevA-based serological studies were less sensitive and less specific than other assay types, such as the VlsE-based C6 peptide assay. However, sera from patients in the initial stages of Lyme disease contained antibodies against RevA, demonstrating that this protein is expressed early in human infection. Thus, RevA may be a useful target for preventative or curative therapies.

ABSTRACTAcquisition of complement regulator factor H (CFH) and factor H-like protein 1 (CFHL1) from human serum enables Borrelia spielmanii, one of the etiological agents of Lyme disease, to evade complement-mediated killing by the human host. Up to three distinct complement regulator-acquiring surface proteins (CRASPs) may be expressed by serum-resistant B. spielmanii, each exhibiting an affinity for CFH and/or CFHL1. Here, we describe the functional characterization of the 15-kDa CRASPs of B. spielmanii, members of the polymorphic Erp (OspE/F-related) protein family, that bind two distinct host complement regulators, CFH and factor H-related protein 1 (CFHR1), but not CFHL1. CFH bound to the B. spielmaniiCRASPs maintained cofactor activity for factor I-mediated C3b inactivation. Three naturally occurring alleles of this protein bound CFH and CFHR1 while a fourth natural allele could not. Comparative sequence analysis of these protein alleles identified a single amino acid, histidine-79, as playing a significant role in CFH/CFHR1 binding, with substitution by an arginine completely abrogating ligand binding. The mutation of His-79 to Arg did not inhibit binding of plasminogen, another known ligand of this group of borrelial outer-surface proteins.