Molecular mechanisms for the subversion of MyD88 signaling by TcpC from virulent uropathogenic Escherichia coli.

The Toll/IL-1 receptor (TIR) domains are crucial signaling modules during innate immune responses involving the Toll-like receptors (TLRs) and IL-1 receptor (IL-1R). Myeloid differential factor 88 (MyD88) is a central TIR domain-containing adapter molecule responsible for nearly all TLR-mediated signaling and is targeted by a TIR domain-containing protein C (TcpC) from virulent uropathogenic Escherichia coli, a common human pathogen. The mechanism of such molecular antagonism has remained elusive. We present the crystal structure of the MyD88 TIR domain with distinct loop conformations that underscore the functional specialization of the adapter, receptor, and microbial TIR domains. Our structural analyses shed light on the genetic mutations at these loops as well as the Poc site. We demonstrate that TcpC directly associates with MyD88 and TLR4 through its predicted DD and BB loops to impair the TLR-induced cytokine induction. Furthermore, NMR titration experiments identify the unique CD, DE, and EE loops from MyD88 at the TcpC-interacting surface, suggesting that TcpC specifically engages these MyD88 structural elements for immune suppression. These findings thus provide a molecular basis for the subversion of TLR signaling by the uropathogenic E. coli virulence factor TcpC and furnish a framework for the design of novel therapeutic agents that modulate immune activation.

Orthostatic hypotension is differentially associated with the cerebellar versus the parkinsonian variant of multiple system atrophy: a comparative study.

Orthostatic hypotension (OH) is a cardinal feature of autonomic failure in multiple system atrophy (MSA); however, there are few comparative data on OH in the motor subtypes of MSA. In the present retrospective study, postural blood pressure drop after 3 min of standing was determined in 16 patients with the cerebellar variant of MSA (MSA-C) and in 17 patients with the Parkinson variant (MSA-P). Twenty idiopathic Parkinson's disease (IPD) patients matched for age, sex, disease duration and dopaminergic therapy served as control group. OH frequency and severity were more pronounced in MSA-C followed by MSA-P and IPD. Differences in brainstem pathology are likely to account for the tight association of MSA-C and OH. A simple standing test should be obligatory in the work-up of patients with sporadic late-onset ataxias.

Patientenpartizipation in der pädiatrischen Versorgungsforschung am Universitätsklinikum Freiburg: von der Projektbeteiligung zum Patientenbeirat.

Participation of patients and relatives in research means that those affected are involved in the research process in a partnership role. Despite the growing importance of participatory approaches and the large number of available concepts, many researchers and patients are faced with the question of how participatory research can be realized and organized in concrete terms. Here we report on our experiences with two different forms of patient participation in research in the context of pediatric health care research at a university hospital: (1) In a project for the development and evaluation of a case management for patients with spinal muscular atrophy, patient representatives have an consultative role. (2) In the patient advisory board, which is to accompany the research activities of the research group at the site continuously and systematically, i.e. in all phases, the participation currently corresponds to a contributory role (involvement) which, in the future, could be moved onto the collaborative stage. In both forms of participation, the essential questions include the selection of the participating patients, the type and extent of participation, and the evaluation of the effect of participation on the research that is carried out. In our experience, both forms of participation add value to research from the perspective of all participants. At the same time, they bring different opportunities and challenges. While in project-based participation the sphere of influence is already delineated by researchers, the context of the patient advisory board provides more room and openness to develop, for example, a research agenda and thus identify new research topics. In our experience, however, sufficient resources (in terms of time and money) are required from all participants, as well as good, trusting cooperation with jointly developed processes to realize both forms of participation.

Chlamydophila pneumoniae downregulates MHC-class II expression by two cell type-specific mechanisms.

Chlamydophila pneumoniae was shown to prevent IFN gamma-inducible upregulation of MHC-class II molecules by secreting chlamydial protease-like activity factor (CPAF) into the cytosol of those host cells which support the complete bacterial replication cycle. CPAF acts by degrading upstream stimulatory factor 1 (USF-1). However, in cells like bone marrow-derived macrophages (BMM), which restrict chlamydial replication, we show that CPAF expression is barely detectable and the expression of USF-1 is induced upon infection with C. pneumoniae. Nevertheless, the infection still reduced base line and prevented IFN gamma-inducible MHC-class II expression. Similar results were obtained with heat-inactivated C. pneumoniae. In contrast, reduction of MHC-class II molecules was not observed in MyD88-deficient BMM. Reduction of IFN gamma-inducible MHC-class II expression by C. pneumoniae in BMM was mediated in part by the MAP-kinase p38. Infection of murine embryonic fibroblasts (MEF) with C. pneumoniae, which allow chlamydial replication, induced the expression of CPAF and decreased USF-1 and MHC-class II expression. Treatment of these cells with heat-inactivated C. pneumoniae reduced USF-1 and MHC-class II expression to a much lower extent. In summary, C. pneumoniae downregulates MHC-class II expression by two cell type-specific mechanisms which are either CPAF-independent and MyD88-dependent like in BMM or CPAF-dependent like in MEFs.

Induction of iNOS by Chlamydophila pneumoniae requires MyD88-dependent activation of JNK.

Innate immune cells produce NO via inducible NO synthase (iNOS) in response to certain infections or upon stimulation with cytokines such as IFN-gamma and TNF. NO plays an important role in host defense against intracellular bacteria including Chlamydophila pneumoniae as a result of its microbicidal activity. In MyD88-deficient mice, which succumb to C. pneumoniae infection, iNOS induction is impaired 6 days postinfection, although pulmonary levels of IFN-gamma and TNF are elevated as in wild-type mice at this time-point. Here, we demonstrate that induction of iNOS in macrophages upon C. pneumoniae infection is controlled by MyD88 via two pathways: NF-kappaB activation and phosphorylation of the MAPK JNK, which leads to the nuclear translocation of c-Jun, one of the two components of the AP-1 complex. In addition, phosphorylation of STAT1 and expression of IFN regulatory factor 1 (IRF-1) were delayed in the absence of MyD88 after C. pneumoniae infection but not after IFN-gamma stimulation. Taken together, our data show that for optimal induction of iNOS during C. pneumoniae infection, the concerted action of the MyD88-dependent transcription factors NF-kappaB and AP-1 and of the MyD88-independent transcription factors phosphorylated STAT1 and IRF-1 is required.

Uropathogenic Escherichia coli strain CFT073 disrupts NLRP3 inflammasome activation.

Successful bacterial pathogens produce an array of virulence factors that allow subversion of the immune system and persistence within the host. For example, uropathogenic Escherichia coli strains, such as CFT073, express Toll/IL-1 receptor-containing (TIR-containing) protein C (TcpC), which impairs TLR signaling, thereby suppressing innate immunity in the urinary tract and enhancing persistence in the kidneys. Here, we have reported that TcpC also reduces secretion of IL-1ß by directly interacting with the NACHT leucin-rich repeat PYD protein 3 (NLRP3) inflammasome, which is crucial for recognition of pathogens within the cytosol. At a low MOI, IL-1ß secretion was minimal in CFT073-infected macrophages; however, IL-1ß release was markedly increased in macrophages infected with CFT073 lacking tcpC. Induction of IL-1ß secretion by CFT073 and tcpC-deficient CFT073 required the NLRP3 inflammasome. TcpC attenuated activation of the NLRP3 inflammasome by binding both NLRP3 and caspase-1 and thereby preventing processing and activation of caspase-1. Moreover, in a murine urinary tract infection model, CFT073 infection rapidly induced expression of the NLRP3 inflammasome in the bladder mucosa; however, the presence of TcpC in WT CFT073 reduced IL-1ß levels in the urine of infected mice. Together, these findings illustrate how uropathogenic E. coli use the multifunctional virulence factor TcpC to attenuate innate immune responses in the urinary tract.

The Gram-negative bacterium Chlamydia trachomatis L2 stimulates tumor necrosis factor secretion by innate immune cells independently of its endotoxin.

The endotoxin of Chlamydia trachomatis L(2), the causative agent of lymphogranuloma venerum, has been described as an endotoxin with an atypical structure and weak stimulatory activity. It is, however, unclear whether chlamydial endotoxin plays a role in the stimulation of innate immune cells upon contact with the whole microorganism C. trachomatis L(2). We show here that chlamydial endotoxin and, as expected, Escherichia coli O55:B5 endotoxin depend on Toll-like receptor 4 without depending on Toll-like receptor 2 to stimulate bone marrow-derived dendritic cells to secrete tumor necrosis factor (TNF). In contrast, the whole microorganism C. trachomatis L(2) induces TNF secretion by innate immune cells independently of Toll-like receptor 4, while stimulation by E. coli O55:B5 depends on Toll-like receptor 4. Furthermore, although TNF secretion of the macrophage cell line RAW264.7 with chlamydial or E. coli O55:B5 endotoxin as well as with the bacterium E. coli O55:B5 is inhibited by the endotoxin-neutralizing compound polymyxin B, C. trachomatis L(2)-induced secretion of TNF cannot be reduced. In accordance with the literature, the potential of chlamydial endotoxin is more than 100-fold weaker than E. coli O55:B5 endotoxin on all cell types tested. We conclude that chlamydial endotoxin is unlikely to be involved in C. trachomatis L(2)-induced release of TNF by innate immune cells.

A cell-culture system for long-term maintenance of elevated hydrostatic pressure with the option of additional tension.

In cell stress research, there is still a need to apply long-term hydrostatic pressure without changing any other environmental condition. We present here a new, open, pressurized chamber system allowing long-term sustained and dynamic application of hydrostatic pressure with the option of additional tension. Based on the computer-controlled Flexcell Strain Unit, we designed a pressurized chamber with a dynamic airflow and a defined membrane extension, which can be regulated by spacers. During operation up to 26.6kPa, O(2) partial pressures and pH in the cell-culture medium do not change compared to control cultures kept at normal atmosphere.

Magnetic resonance imaging of the ear for patient-specific reconstructive surgery.

INTRODUCTION: Like a fingerprint, ear shape is a unique personal feature that should be reconstructed with a high fidelity during reconstructive surgery. Ear cartilage tissue engineering (TE) advantageously offers the possibility to use novel 3D manufacturing techniques to reconstruct the ear, thus allowing for a detailed auricular shape. However it also requires detailed patient-specific images of the 3D cartilage structures of the patient's intact contralateral ear (if available). Therefore the aim of this study was to develop and evaluate an imaging strategy for acquiring patient-specific ear cartilage shape, with sufficient precision and accuracy for use in a clinical setting. METHODS AND MATERIALS: Magnetic resonance imaging (MRI) was performed on 14 volunteer and six cadaveric auricles and manually segmented. Reproducibility of cartilage volume (Cg.V), surface (Cg.S) and thickness (Cg.Th) was assessed, to determine whether raters could repeatedly define the same volume of interest. Additionally, six cadaveric auricles were harvested, scanned and segmented using the same procedure, then dissected and scanned using high resolution micro-CT. Correlation between MR and micro-CT measurements was assessed to determine accuracy. RESULTS: Good inter- and intra-rater reproducibility was observed (precision errors <4% for Cg.S and <9% for Cg.V and Cg.Th). Intraclass correlations were good for Cg.V and Cg.S (>0.82), but low for Cg.Th (<0.23) due to similar average Cg.Th between patients. However Pearson's coefficients showed that the ability to detect local cartilage shape variations is unaffected. Good correlation between clinical MRI and micro-CT (r>0.95) demonstrated high accuracy. DISCUSSION AND CONCLUSION: This study demonstrated that precision and accuracy of the proposed method was high enough to detect patient-specific variation in ear cartilage geometry. The present study provides a clinical strategy to access the necessary information required for the production of 3D ear scaffolds for TE purposes, including detailed patient-specific shape. Furthermore, the protocol is applicable in daily clinical practice with existing infrastructure.

Toll-like receptors 2 and 4 regulate the frequency of IFNγ-producing CD4+ T-cells during pulmonary infection with Chlamydia pneumoniae.

TLR2 and TLR4 are crucial for recognition of Chlamydia pneumoniae in vivo, since infected TLR2/4 double-deficient mice are unable to control the infection as evidenced by severe loss of body weight and progressive lethal pneumonia. Unexpectedly, these mice display higher pulmonary levels of the protective cytokine IFNγ than wild type mice. We show here, that antigen-specific CD4(+) T-cells are responsible for the observed IFNγ-secretion in vivo and their frequency is higher in TLR2/4 double-deficient than in wild type mice. The capacity of TLR2/4 double-deficient dendritic cells to re-stimulate CD4(+) T-cells did not differ from wild type dendritic cells. However, the frequency of CD4(+)CD25(+)Foxp3(+) T-cells was considerably higher in wild type compared to TLR2/4 double-deficient mice and was inversely related to the number of IFNγ-secreting CD4(+) effector T-cells. Despite increased IFNγ-levels, at least one IFNγ-mediated response, protective NO-secretion, could not be induced in the absence of TLR2 and 4. In summary, CD4(+)CD25(+)Foxp3(+) regulatory T-cells fail to expand in the absence of TLR2 and TLR4 during pulmonary infection with C. pneumoniae, which in turn enhances the frequency of CD4(+)IFNγ(+) effector T-cells. Failure of IFNγ to induce NO in TLR2/4 double-deficient cells represents one possible mechanism why TLR2/4 double-deficient mice are unable to control pneumonia caused by C. pneumoniae and succumb to the infection.

Differential involvement of TLR2 and TLR4 in host survival during pulmonary infection with Chlamydia pneumoniae.

The relevance of TLR2 and TLR4 for recognizing Chlamydia pneumoniae in vivo during pulmonary infection and to survive the infection was explored. We found that early immune responses triggered by C. pneumoniae partially depended on TLR2, but not on TLR4. The chemokines MIP-2 and MIP-1alpha were not induced, while IL-12p40 levels were higher in TLR2(-/-) mice compared to wild-type mice. Secretion of TNF, keratinocyte-derived chemokine and monocyte chemoattractant protein-1 was attenuated in TLR2(-/-) mice, while IFN-gamma was increased as in wild-type mice. The pulmonary cyto- and chemokine response of TLR2(-/-) x TLR4(d/d) was similar to TLR2(-/-) mice. TLR2(-/-) and TLR2(-/-) x TLR4(d/d) mice also attracted fewer polymorphonuclear neutrophils into the lung, while TLR4(d/d) mice recruited them. Attenuated recruitment of polymorphonuclear neutrophils correlated with reduced weight loss in TLR2(-/-) and TLR2(-/-) x TLR4(d/d) mice and a lower chlamydial burden 3 days post infection. At 9 days post infection, TLR2(-/-) and TLR2(-/-) x TLR4(d/d) mice produced cyto- and chemokines as efficiently as wild-type mice, indicating that the involvement of TLR in inflammation varies over time. All TLR2(-/-) x TLR4(d/d) mice succumbed to the infection, while about 50% of TLR2(-/-) mice died. Taken together, the function of TLR2 and TLR4 is required to survive pulmonary infection with C. pneumoniae.

Pathologically elevated cyclic hydrostatic pressure induces CD95-mediated apoptotic cell death in vascular endothelial cells.

We describe cyclic hydrostatic pressure of 200/100 mmHg with a frequency of 85/min as a hemodynamically relevant pathological condition enforcing apoptosis in endothelial cells (EC) after 24 h of treatment. This went along with an increase of CD95 and CD95L surface expression, shedding of CD95L into the supernatant, cleavage of caspase-3 and caspase-8, and elevated JNK-2, c-Jun, and CD95L mRNA expression. Furthermore, increased DNA-binding activity of the AP-1 transcription factor family members FRA-1 and c-Jun was observed. This activation was reduced by inhibition of JNK, which subsequently prevented elevated CD95L mRNA expression. Caspase inhibitors and a CD95L-neutralizing antibody also reduced EC apoptosis. Most of the pressure-induced events were most prominent at 24 and 48 h. However, after 48 h, the CD95/CD95L expression pattern switched back to CD95-/CD95L+ and the specific death rate decreased. Cyclic pathological hydrostatic pressure is a novel type of stress to EC that renders them susceptible to CD95/CD95L-mediated autoapoptosis and/or paracrine apoptosis accompanied by upregulation of intracellular molecules known to trigger both apoptosis and survival.

Polymorphonuclear neutrophils improve replication of Chlamydia pneumoniae in vivo upon MyD88-dependent attraction.

Chlamydia pneumoniae, an obligate intracellular bacterium, causes pneumonia in humans and mice. In this study, we show that GR1+/CD45+ polymorphonuclear neutrophils (PMN) surprisingly increase the bacterial load of C. pneumoniae in vivo. Upon intranasal infection of wild-type mice, the lung weight is increased; the cytokines TNF, IL-12p40, and IFN-gamma, as well as the chemokines keratinocyte-derived chemokine, MCP-1, and MIP-2 are secreted; and GR1+/CD45+ PMN are recruited into lungs 3 days postinfection. In contrast, in infected MyD88-deficient mice, which lack a key adaptor molecule in the signaling cascade of TLRs and IL-1R family members, the increase of the lung weight is attenuated, and from the analyzed cyto- and chemokines, only IL-12p40 is detectable. Upon infection, almost no influx of inflammatory cells into lungs of MyD88-deficient mice can be observed. Six days postinfection, however, MyD88-deficient mice were able to produce TNF, IFN-gamma, keratinocyte-derived chemokine, and MCP-1 in amounts similar to wild-type mice, but failed to secrete IL-12p40 and MIP-2. At this time point, the infection increased the lung weight to a level similar to wild-type mice. Curiously, the chlamydial burden in MyD88-deficient mice 3 days postinfection is lower than in wild-type mice, a finding that can be reproduced in wild-type mice by depletion of GR1+ cells. In analyzing how PMN influence the chlamydial burden in vivo, we find that PMN are infected and enhance the replication of C. pneumoniae in epithelial cells. Thus, the lower chlamydial burden in MyD88-deficient mice can be explained by the failure to recruit PMN.

In chronic pancreatitis, widespread emergence of TRAIL receptors in epithelia coincides with neoexpression of TRAIL by pancreatic stellate cells of early fibrotic areas.

TRAIL (TNF-related apoptosis-inducing ligand) induces apoptosis by cross-linking of the two TRAIL receptors that contain a death domain, TRAIL-R1 and TRAIL-R2. TRAIL-R3 and TRAIL-R4 are receptors that do not transmit an apoptotic signal. Our aim was to determine the expression of TRAIL and its receptors in normal pancreas and chronic pancreatitis. We applied real-time PCR, immunohisto(cyto)chemistry, and nick-end labeling of apoptosis. In normal pancreas, a minor subset of acinar cells coexpressed TRAIL-R2 and TRAIL-R4, whereas ductular epithelium and interstitial fibroblast-like cells (FLC) expressed TRAIL-R4. TRAIL-R1 and TRAIL-R3 were not detected in normal pancreas. In chronic pancreatitis, the exocrine epithelium strongly expressed TRAIL-R1, -R2, -R4, and, to a lesser extent, TRAIL-R3. Islets focally neoexpressed TRAIL-R1 and -R2 and intensely expressed TRAIL-R4. Changes in TRAIL receptor expression were most pronounced in areas of inflammatory infiltration and active fibrosis. In normal pancreas, expression of TRAIL was low on the mRNA level and undetectable on the protein level. In chronic pancreatitis, FLC in areas of active fibrosis expressed TRAIL. In addition, apoptosis were most numerous in these areas. We show that these FLC are pancreatic stellate cells. Pancreatic stellate cells express TRAIL in vivo and in vitro, and TRAIL expression is enhanced by IFN-gamma. Our findings indicate that the TRAIL/TRAIL receptor system is likely to be involved in chronic pancreatitis and suggest that pancreatic stellate cells may directly contribute to acinar regression by inducing apoptosis of parenchymal cells in a TRAIL-dependent manner.

Role of chlamydial heat shock protein 60 in the stimulation of innate immune cells by Chlamydia pneumoniae.

Chlamydia pneumoniae stimulates potently maturation of and cytokine secretion by bone marrow-derived dendritic cells (BMDDC). BMDDC responses depend mainly on Toll-like receptor (TLR)2 and to a minor extent on TLR4. We demonstrate here using C. pneumoniae in an infectious model with the replication-permissive epithelial cell line HEp2 that HSP60 is produced in substantial amounts in chlamydial inclusions during infection. Electron microscopy of chlamydial inclusions revealed that HSP60 was mainly associated with reticulate bodies, but was also located in between the different chlamydial developmental forms. Supernatants of permissive HEp2 cells infected with C. pneumoniae contained soluble chlamydial HSP60 as demonstrated by Western blotting and were able to stimulate BMDDC of wild-type mice. The stimulatory capacity of culture supernatants correlated with the presence of chlamydial HSP60. In contrast, BMDDC from TLR4-mutant mice crossed to TLR2-deficient mice were not stimulated by the culture supernatant, indicating that chlamydial HSP60 but not cytokines, possibly secreted by infected HEp2 cells, are responsible for the observed stimulation of BMDDC. Purified recombinant HSP60 from C. pneumoniae stimulated BMDDC in a TLR2- and TLR4-dependent fashion similar to the whole microorganism. In summary, these data suggest chlamydial HSP60 as an important mediator of inflammatory responses during infection with C. pneumoniae.