Arbeitsgruppe "Funktionelle Genomforschung"
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Streptococcus pneumoniae has evolved versatile strategies to colonize the nasopharynx of humans. Colonization is facilitated by direct interactions with host cell receptors or via binding to components of the extracellular matrix. In addition, pneumococci hijack host-derived extracellular proteases such as the serine protease plasmin(ogen) for ECM and mucus degradation as well as colonization. S. pneumoniae expresses strain-dependent up to four serine proteases. In this study, we assessed the role of secreted or cell-bound serine proteases HtrA, PrtA, SFP, and CbpG, in adherence assays and in a mouse colonization model. We hypothesized that the redundancy of serine proteases compensates for the deficiency of a single enzyme. Therefore, double and triple mutants were generated in serotype 19F strain EF3030 and serotype 4 strain TIGR4. Strain EF3030 produces only three serine proteases and lacks the SFP encoding gene. In adherence studies using Detroit-562 epithelial cells, we demonstrated that both TIGR4Δcps and 19F mutants without serine proteases or expressing only CbpG, HtrA, or PrtA have a reduced ability to adhere to Detroit-562 cells. Consistent with these results, we show that the mutants of strain 19F, which preferentially colonizes mice, abrogate nasopharyngeal colonization in CD-1 mice after intranasal infection. The bacterial load in the nasopharynx was monitored for 14 days. Importantly, mutants showed significantly lower bacterial numbers in the nasopharynx two days after infection. Similarly, we detected a significantly reduced pneumococcal colonization on days 3, 7, and 14 post-inoculations. To assess the impact of pneumococcal serine proteases on acute infection, we infected mice intranasally with bioluminescent and invasive TIGR4 or isogenic triple mutants expressing only CbpG, HtrA, PrtA, or SFP. We imaged the acute lung infection in real-time and determined the survival of the mice. The TIGR4lux mutant expressing only PrtA showed a significant attenuation and was less virulent in the acute pneumonia model. In conclusion, our results showed that pneumococcal serine proteases contributed significantly to pneumococcal colonization but played only a minor role in pneumonia and invasive diseases. Because colonization is a prerequisite for invasive diseases and transmission, these enzymes could be promising candidates for the development of antimicrobials to reduce pneumococcal transmission.
Background and Aims
Gallbladder cancer (GBC) is a neglected disease with substantial geographical variability: Chile shows the highest incidence worldwide, while GBC is relatively rare in Europe. Here, we investigate the causal effects of risk factors considered in current GBC prevention programs as well as C‐reactive protein (CRP) level as a marker of chronic inflammation.
Approach and Results
We applied two‐sample Mendelian randomization (MR) using publicly available data and our own data from a retrospective Chilean and a prospective European study. Causality was assessed by inverse variance weighted (IVW), MR‐Egger regression, and weighted median estimates complemented with sensitivity analyses on potential heterogeneity and pleiotropy, two‐step MR, and mediation analysis. We found evidence for a causal effect of gallstone disease on GBC risk in Chileans (P = 9 × 10−5) and Europeans (P = 9 × 10−5). A genetically elevated body mass index (BMI) increased GBC risk in Chileans (P = 0.03), while higher CRP concentrations increased GBC risk in Europeans (P = 4.1 × 10−6). European results suggest causal effects of BMI on gallstone disease (P = 0.008); public Chilean data were not, however, available to enable assessment of the mediation effects among causal GBC risk factors.
Conclusions
Two risk factors considered in the current Chilean program for GBC prevention are causally linked to GBC risk: gallstones and BMI. For Europeans, BMI showed a causal effect on gallstone risk, which was itself causally linked to GBC risk.
Mast cells reside on and near the cerebral vasculature, the predominant site of pneumococcal entry into the central nervous system (CNS). Although mast cells have been reported to be crucial in protecting from systemic bacterial infections, their role in bacterial infections of the CNS remained elusive. Here, we assessed the role of mast cells in pneumococcal infection in vitro and in vivo. In introductory experiments using mouse bone marrow-derived mast cells (BMMC), we found that (i) BMMC degranulate and release selected cytokines upon exposure to Streptococcus pneumoniae, (ii) the response of BMMC varies between different pneumococcal serotypes and (iii) is dependent on pneumolysin. Intriguingly though, apart from a slight enhancement of cerebrospinal fluid (CSF) pleocytosis, neither two different mast cell-deficient Kit mutant mouse strains (WBB6F1-KitW/Wv and C57BL/6 KitW-sh/W-sh mice) nor pharmacologic mast cell stabilization with cromoglycate had any significant impact on the disease phenotype of experimental pneumococcal meningitis. The incomplete reversal of the enhanced CSF pleocytosis by local mast cell engraftment suggests that this phenomenon is caused by other c-Kit mutation-related mechanisms than mast cell deficiency. In conclusion, our study suggests that mast cells can be activated by S. pneumoniae in vitro. However, mast cells do not play a significant role as sentinels of pneumococcal CSF invasion and initiators of innate immunity in vivo.
The autism susceptibility locus on human chromosome 7q32 contains the maternally imprinted MEST and the non-imprinted COPG2 and TSGA14 genes. Autism is a disorder of the ‘social brain’ that has been proposed to be due to an overbalance of paternally expressed genes. To study regulation of the 7q32 locus during anthropoid primate evolution, we analyzed the methylation and expression patterns of MEST, COPG2, and TSGA14 in human, chimpanzee, Old World monkey (baboon and rhesus macaque), and New World monkey (marmoset) cortices. In all human and anthropoid primate cortices, the MEST promoter was hemimethylated, as expected for a differentially methylated imprinting control region, whereas the COPG2 and TSGA14 promoters were completely demethylated, typical for transcriptionally active non-imprinted genes. The MEST gene also showed comparable mRNA expression levels in all analyzed species. In contrast, COPG2 expression was downregulated in the human cortex compared to chimpanzee, Old and New World monkeys. TSGA14 either showed no differential regulation in the human brain compared to chimpanzee and marmoset or a slight upregulation compared to baboon. The human-specific downregulation supports a role for COPG2 in the development of a ‘social brain’. Promoter methylation patterns appear to be more stable during evolution than gene expression patterns, suggesting that other mechanisms may be more important for inter-primate differences in gene expression.
Differences in Mouse Hepatic Thyroid Hormone Transporter Expression with Age and Hyperthyroidism
(2015)
Background: Clinical features of thyroid dysfunction vary with age, and an oligosymptomatic presentation of hyperthyroidism is frequently observed in the elderly. This suggests age modulation of thyroid hormone (TH) action, which may occur, for example, by alterations in TH production, metabolism and/or TH action in target organs. Objectives: In this paper, we address possible changes in TH transporter expression in liver tissues as a mechanism of age-dependent variation in TH action. Methods: Chronic hyperthyroidism was induced in 4- and 20-month-old C57BL6/NTac male mice (n = 8-10) by intraperitoneal injections of 1 µg/g body weight <smlcap>L</smlcap>-thyroxine (T<sub>4</sub>) every 48 h over 7 weeks. Control animals were injected with PBS. Total RNA was isolated from liver samples for analysis of the TH transporter and TH-responsive gene expression. TH concentrations were determined in mice sera. Results: Baseline serum free T<sub>4</sub> (fT<sub>4</sub>) concentrations were significantly higher in euthyroid young compared to old mice. T<sub>4</sub> treatment increased total T<sub>4</sub>, fT<sub>4</sub> and free triiodothyronine to comparable concentrations in young and old mice. In the euthyroid state, TH transporter expression was significantly higher in old than in young mice, except for Mct8 and Oatp1a1 expression levels. Hyperthyroidism resulted in upregulation of Mct10, Lat1 and Lat2 in liver tissue, while Oatp1a1, Oatp1b2 and Oatp1a4 expression was downregulated. This effect was preserved in old animals. Conclusion: Here, we show age-dependent differences in TH transporter mRNA expression in the euthyroid and hyperthyroid state of mice focusing on the liver as a classical TH target organ.
Die vorliegende Arbeit adressiert die Nutzbarkeit des humanen Speichelproteoms als diagnostisches Instrument im Kontext einer oralen Mukositis bei Kopf- und Halskarzinoms. Als häufigste Nebenwirkung einer Radio(chemo)therapie kann die Mukositis therapielimitierend sein und hat für betroffene Patienten meist eine Einschränkung ihrer Lebensqualität zur Folge. Trotz der guten Verfügbarkeit von Speichel existieren wenige Studien, welche zeigen, dass das Speichelproteom für die Diagnostik einer Krankheit oder zur Therapieentscheidung nutzbar ist. Das hat unter anderem seinen Grund in der Komplexität der massenspektrometrischen Methode. Die erste Veröffentlichung (Golatowski et al. 2013) erarbeitete deshalb einen Standard in der Probengewinnung von Speichel. Als Ergebnis steht die Empfehlung zur Nutzung eines Paraffin-Kaugummis, aufgrund des hohen Speichelvolumens und der guten Vergleichbarkeit mit der nichtstimulierten Salivation beim identifizierten Proteom. In einer zweiten Veröffentlichung (Jehmlich & Golatowski et al. 2014) wurden C18 Mikrosäulen verschiedener Hersteller bezüglich ihres Einflusses auf die Proteinidentifizierung verglichen. Die Säulen sind notwendig für die Entsalzung und Aufreinigung eines Peptidgemisches. Mit allen verwendeten Säulen konnten ähnliche Ergebnisse erzielt werden, wobei die ZipTip® µC18 sowie C18 Systeme der OASIS® HLB μElution 96er Well Platte und TopTip® C18 Pipettenspitzen leicht überlegen sind. In der letzten Arbeit (Jehmlich et al. 2015) wurden die gewonnenen Erkenntnisse genutzt, um die Speichelproben von Patienten mit Kopf- und Halskarzinom zu untersuchen. Insgesamt zeigten wir die Möglichkeit, alterierte Proteine zwischen zwei Patientengruppen massenspektrometrisch zu detektieren. Mit den gefundenen Daten konnte demonstrieren werden, dass massenspektrometrische Techniken geeignet sind, um schon vor Behandlungsbeginn Patienten zu identifizieren, die für die Entwicklung einer oralen Mukositis prädisponiert sind. Es ist hierbei die Proteinklasse der Metalloproteinasen hervorzuheben, da diese für einen therapeutischen Ansatz gegen Mukositis interessant sind. In Zukunft werden jedoch größere und voraussichtlich multizentrische Studien erforderlich sein, um ausreichend große Patientenkohorten zusammenzustellen und die Klassifikation speziell für Patienten ohne Mukositisrisiko sensitiver zu gestalten.
Humanity is plagued by many diseases. Beside environmental influences, many --- if not all --- diseases are also subject to genetic predisposition and then display molecular alterations such as proteomic or metabolic aberrations. The elucidation of the molecular principles underlying human diseases is one of the prime goals of biomedical research. To this end, there has been an advent of large-scale omics profiling studies. While the field of molecular biology has experienced tremendous development, data analysis remains a bottleneck. In the context of this thesis, we developed a number of analysis strategies for different types of omics data resulting from different experimental settings. These include approaches for associations studies for plasma miRNAs and time-resolved plasma omics data. Furthermore, we devised analyses of different RNA-Seq transcriptome profiling studies coping with problems such as lack of replicates or multifactorial experimental design. We also designed machine learning frameworks for the identification of discriminatory biomolecular signatures analysing case-control or time-to-event data. All of the strategies mentioned above were developed and applied in the contexts of multi-disciplinary endeavours. They aided in the identification of plasma miRNAs associated with age, sex, and BMI as well as plasma miRNAs bearing potential as diagnostic biomarkers for non-alcoholic fatty liver disease (NAFLD). This thesis significantly contributed to a study demonstrating the utility of plasma miRNAs as prognostic biomarkers for major cardiovascular events such as ST-elevation myocardial infarction. Our approaches for analysing RNA-Seq data aided in the characterisation of murine models for Alzheimers disease and the transcriptional response of human gingiva fibroblasts to ionizing radiation exposure. Furthermore, the developed approaches were applied for studying a human model for thyrotoxicosis and for the successful identification of a multi-omics plasma biomarker signature of thyroid status. We are only beginning to understand the molecular principles underlying human diseases. The approaches and results presented in this thesis will contribute to improved understanding of biomolecular processes involved in common diseases such as Alzheimers disease, NAFLD, and cardiovascular diseases.
Transfusion-related acute lung injury (TRALI) is an adverse transfusion reaction and the major cause of transfusion-related mortality. The syndrome occurs within six hours after transfusion and is characterized by acute respiratory distress and the occurrence of a non-cardiogenic, bilateral lung edema. TRALI is almost entirely induced by leukocyte-reactive substances which are present in the blood product and get transferred to the recipient during transfusion. The majority of cases (~80%) is caused by leukocyte-reactive immunoglobulins and is accordingly classified as immune-mediated TRALI. The responsible antibodies are generated via alloimmunization and are directed against human leukocyte antigens of class I and II or human neutrophil alloantigens (HNA). Within the HNA class, HNA-3a antibodies have an exceptional clinical relevance as they are most frequently involved in severe and fatal TRALI cases. The high mortality was associated with their characteristic ability to induce a strong neutrophil aggregation response. The described clinical relevance of HNA-3a antibody-mediated TRALI motivates the screening for new strategies for preventive or acute pharmacologic intervention. Knowledge of the molecular pathomechanisms is a crucial prerequisite and thus, respective investigations are required. In order to achieve this goal, HNA-3a antibody-induced cytotoxicity and aggregation were assessed on the molecular level by usage of flow cytometry, the granulocyte agglutination test and by phosphoproteome analysis. The current study provides insight into molecular processes during HNA-3a antibody-induced neutrophil responses and is the first to assess neutrophils using global, gel-free phosphoproteome analyses. Accordingly, it is the first to provide neutrophil phosphoproteome data in the context of TRALI. Gel-free phosphoproteome analyses of primary neutrophils required the highly selective and sensitive phosphopeptide enrichment from stable and sufficiently large protein extracts. However, an appropriate workflow did not exist and was hence developed by sequential protocol optimization steps. The developed workflow was finally proven suitable for comparative gel-free phosphoproteomics when detecting the formyl-methionyl-leucyl-phenylalanine-induced activation of extracellular signal-regulated kinase 1/2 (ERK1/2) signaling in a proof-of-principle experiment. The following single parameter analyses were conducted to investigate neutrophils for their responses to HNA-3a antibodies in absence and presence of proinflammatory priming conditions. Results revealed that the direct stimulation of neutrophils with HNA-3a antibodies will likely not cause the induction of cytotoxic effector functions. In contrast, neutrophils react predominantly by aggregation, a process which is potentially mediated by integrins and causes a secondary, subthreshold activation of solely ERK2. Accordingly, only the neutrophil aggregation response could also be enhanced by an appropriate priming. Taken together, the single parameter analyses proved neutrophil aggregation as the main pathomechanism in HNA-3a antibody-mediated TRALI and thus, the underlying signaling pathways were investigated by global, gel-free phosphoproteomics. The following phosphoproteome analyses indicated the induction of a biphasic signaling during 30 minutes of HNA-3a antibody treatment and signaling pathways of Rho family GTPases could be associated with the first and the second phase. Additionally, the involvement of ERK signaling was indicated in the second phase and this result corroborated thus the data of the previous single parameter analyses. The comprehensive analysis of the identified signaling pathways revealed Rho, Rac and Cdc42 as central regulators and the specific inhibition of Rho in the following validating experiments led very intriguingly to a significant enhancement of HNA-3a antibody-mediated neutrophil aggregation. Hence, this result indicated a potential inhibitory effect of HNA-3a antibodies on Rho activity. Therefore, Rho inhibition was suggested to occur in parallel to an adhesion-inducing signaling pathway and might hence be involved in the stabilization of neutrophil aggregates in HNA-3a antibody-induced TRALI. The results from this doctoral thesis contributed to the generation of a new pathogenesis model for HNA-3a antibody-mediated TRALI. In this model, neutrophils respond to direct HNA-3a antibody exposure predominantly by homotypic aggregation. These potentially very stable and primed aggregates accumulate in the lung and are susceptible to parallel, proinflammatory stimulation. Subsequently, this cascade leads to full neutrophil activation and finally to TRALI induction.
