BMPs vermitteln ihre zellulären Effekte durch Rekrutierung und Aktivierung von zwei Typen spezifischer, membranständiger Rezeptoren. Die genauen Mechanismen der Rezeptorakivierung und die Komposition eines funktionellen, signalvermittelnden Komplexes auf der Zelloberfläche sind in den letzten Jahren genau untersucht worden. Die dimere Natur aller BMPs, die Promiskuitivität der BMPs sowie der entsprechenden Rezeptoren und die unterschiedlichen Rezeptorkonformationen (PFC, BISC) erschweren jedoch die experimentelle Zugänglichkeit dieser Proteinfamilie. Um den Einfluss der Membranverankerung der Rezeptoren auf deren Affinität zu einzelnen Liganden zu untersuchen, wurden verschiedene Methoden evaluiert, die eine quantitative Kopplung an Plasmamembranen ermöglichten. Die BMP Rezeptorektodomänen wurden u.a. mittels einer lysin-spezifischen Kopplung lipidiert, oder aber als His6-Ektodomänen an membranintegrierte Chelatlipide gekoppelt. / BMPs elicit their cellular functions via recruitment and activation of specific receptor serin/threonine receptor kinases. The precise mechanisms leading to receptor activation and the composition of a functional signal transducing complex on the cell surface has been investigated intensively over the last decades. The dimeric nature of all BMPs, the promiscuity of both, the ligands and the receptors and the different receptor conformations on the cell surface (PFC, BISC) hamper the experimental accessibility of this protein family. To study the membrane anchorage's influence of the receptors on their affinity towards single ligands, different methods were evaluated that enabled us to couple the receptor ectodomains in a quantitative manner to plasma membranes. The BMP receptor ectodomains were, among other techniques, lipidated in a lysine specific way or coupled as hexahistidine fusion proteins to membrane integrated chelating lipids.

O objetivo deste trabalho foi avaliar, in vitro, os efeitos de diferentes concentrações do fator de crescimento transformador beta 1 (TGF-β1) em células-tronco derivadas da polpa de dentes decíduos esfoliados humanos (SHED), com relação à viabilidade, proliferação, migração e diferenciação celular. As SHED foram mantidas em meio de cultura MEMα + soro fetal bovino (FBS) 10% + penicilina e estreptomicina 1% e tratadas com TGF-β1 na concentração de 1,0; 5,0 e 10,0 ng/mL. Após 1, 3, 5 e 7 dias, foram avaliadas a viabilidade celular pelo método MTT e a proliferação pelo método SRB. Após 24 h de tratamento com TGF-β1, foi realizado um ensaio de migração celular por meio de insertos com poros de 8 μm. Para a avaliação da diferenciação celular de SHED em odontoblastos foram analisados por meio da RT-PCR os marcadores DSPP e DMP-1, após tratamento com TGF-β1 nas diferentes concentrações por 14 dias. Os resultados foram submetidos à ANOVA seguido do teste de Tukey. Em relação à viabilidade celular, as diferentes concentrações de TGF-β1 não tiveram efeito citotóxico sobre SHED. As células tratadas com diferentes concentrações de TGF-β1 apresentaram maiores taxas de proliferação que as do controle negativo (MEMα + 10% de FBS) a partir do 3o dia (p=0,000). Observou-se maiores taxas de migração em direção aos meios contendo TGF-β1, mas sem diferença estatisticamente significativa entre as diferentes concentrações utilizadas, entretanto, houve diferença estatisticamente significativa entre as diferentes concentrações de TGF-β1 com o controle positivo (p=0,000), controle negativo (p=0,000) e entre o controle positivo e negativo (p=0,002). A expressão de DMP-1 foi observada de forma crescente nas doses de 1,0 e 5,0 ng/mL de TGF-β1 ao longo do período (1, 7 e 14 dias) e na dose de 10,0 ng/mL a marcação foi mais intensa desde o primeiro dia do estímulo. Em relação à expressão de DSPP, o grupo tratado com 10,0 ng/mL apresentou marcação após 14 dias de tratamento. Sendo assim, este estudo permite concluir que as diferentes concentrações de TGF-β1 estimularam a proliferação e migração celular, sem efeito citotóxico sobre as células ao longo do período do estudo. Em relação à diferenciação celular a concentração 10,0 ng/mL de TGF-β1 estimulou à expressão de DMP-1 e DSPP. / The aim of this study was to evaluate, in vitro, the effect of transforming growth factor beta 1 (TGF-β1) in stem cells derived from the pulp of human exfoliated deciduous teeth (SHED) regarding to cell viability, proliferation, migration and differentiation. SHED were maintained in MEMα culture medium + 10% fetal bovine serum (FBS) + 1% penicillin and streptomycin, and treated with TGF-β1 at the following concentrations of 1.0; 5.0 and 10.0 ng/mL. After 1, 3, 5 and 7 days, cell viability was assessed by MTT assay and proliferation by the SRB method. After 24h of TGF-β1 treatment, cell migration assay was carried out using inserts of 8 μm pore size. To evaluate SHED differentiation into odontoblasts, DMP-1 and DSPP markers were analyzed by RT-PCR, after treatment at different concentrations of TGF-β1 for 14 days. The results were submitted by ANOVA and Tukey test. With respect to cell viability, the different TGF-β1 concentrations did not have cytotoxic effect on SHED. The cells treated by different TGF-β1 concentrations showed higher proliferation rates than those of the negative control (MEMα + 10% FBS) after the third day (p = 0.000). Higher rates of migration towards the media containing TGF-β1 were observed, but there were no statistically significant differences among the concentrations. All different TGF-β1 concentrations showed statistically significant differences with the positive control (p=0.000) and negative control (p=0.000). Statistically significant differences were observed between positive and negative control (p=0.002). DMP-1 expression was observed incrementally at TGF-β1 concentrations of 1.0 and 5.0 ng/mL at 1, 7, and 14 days and the concentration of 10.0 ng/mL was more intense from day one of the stimulus. DSPP expression was more intense after 14 days of treatment with the concentration of 10.0 ng/mL. Thus, this study concluded that different TGF-β1 concentrations stimulated cell proliferation and migration, without cytotoxic effect on the cells throughout the study period. From the perspective of cell differentiation, TGF-β1 concentration of 10.0 ng/mL was capable of stimulating DMP-1 and DSPP expression.

O objetivo deste trabalho foi avaliar, in vitro, os efeitos de diferentes concentrações do fator de crescimento transformador beta 1 (TGF-β1) em células-tronco derivadas da polpa de dentes decíduos esfoliados humanos (SHED), com relação à viabilidade, proliferação, migração e diferenciação celular. As SHED foram mantidas em meio de cultura MEMα + soro fetal bovino (FBS) 10% + penicilina e estreptomicina 1% e tratadas com TGF-β1 na concentração de 1,0; 5,0 e 10,0 ng/mL. Após 1, 3, 5 e 7 dias, foram avaliadas a viabilidade celular pelo método MTT e a proliferação pelo método SRB. Após 24 h de tratamento com TGF-β1, foi realizado um ensaio de migração celular por meio de insertos com poros de 8 μm. Para a avaliação da diferenciação celular de SHED em odontoblastos foram analisados por meio da RT-PCR os marcadores DSPP e DMP-1, após tratamento com TGF-β1 nas diferentes concentrações por 14 dias. Os resultados foram submetidos à ANOVA seguido do teste de Tukey. Em relação à viabilidade celular, as diferentes concentrações de TGF-β1 não tiveram efeito citotóxico sobre SHED. As células tratadas com diferentes concentrações de TGF-β1 apresentaram maiores taxas de proliferação que as do controle negativo (MEMα + 10% de FBS) a partir do 3o dia (p=0,000). Observou-se maiores taxas de migração em direção aos meios contendo TGF-β1, mas sem diferença estatisticamente significativa entre as diferentes concentrações utilizadas, entretanto, houve diferença estatisticamente significativa entre as diferentes concentrações de TGF-β1 com o controle positivo (p=0,000), controle negativo (p=0,000) e entre o controle positivo e negativo (p=0,002). A expressão de DMP-1 foi observada de forma crescente nas doses de 1,0 e 5,0 ng/mL de TGF-β1 ao longo do período (1, 7 e 14 dias) e na dose de 10,0 ng/mL a marcação foi mais intensa desde o primeiro dia do estímulo. Em relação à expressão de DSPP, o grupo tratado com 10,0 ng/mL apresentou marcação após 14 dias de tratamento. Sendo assim, este estudo permite concluir que as diferentes concentrações de TGF-β1 estimularam a proliferação e migração celular, sem efeito citotóxico sobre as células ao longo do período do estudo. Em relação à diferenciação celular a concentração 10,0 ng/mL de TGF-β1 estimulou à expressão de DMP-1 e DSPP. / The aim of this study was to evaluate, in vitro, the effect of transforming growth factor beta 1 (TGF-β1) in stem cells derived from the pulp of human exfoliated deciduous teeth (SHED) regarding to cell viability, proliferation, migration and differentiation. SHED were maintained in MEMα culture medium + 10% fetal bovine serum (FBS) + 1% penicillin and streptomycin, and treated with TGF-β1 at the following concentrations of 1.0; 5.0 and 10.0 ng/mL. After 1, 3, 5 and 7 days, cell viability was assessed by MTT assay and proliferation by the SRB method. After 24h of TGF-β1 treatment, cell migration assay was carried out using inserts of 8 μm pore size. To evaluate SHED differentiation into odontoblasts, DMP-1 and DSPP markers were analyzed by RT-PCR, after treatment at different concentrations of TGF-β1 for 14 days. The results were submitted by ANOVA and Tukey test. With respect to cell viability, the different TGF-β1 concentrations did not have cytotoxic effect on SHED. The cells treated by different TGF-β1 concentrations showed higher proliferation rates than those of the negative control (MEMα + 10% FBS) after the third day (p = 0.000). Higher rates of migration towards the media containing TGF-β1 were observed, but there were no statistically significant differences among the concentrations. All different TGF-β1 concentrations showed statistically significant differences with the positive control (p=0.000) and negative control (p=0.000). Statistically significant differences were observed between positive and negative control (p=0.002). DMP-1 expression was observed incrementally at TGF-β1 concentrations of 1.0 and 5.0 ng/mL at 1, 7, and 14 days and the concentration of 10.0 ng/mL was more intense from day one of the stimulus. DSPP expression was more intense after 14 days of treatment with the concentration of 10.0 ng/mL. Thus, this study concluded that different TGF-β1 concentrations stimulated cell proliferation and migration, without cytotoxic effect on the cells throughout the study period. From the perspective of cell differentiation, TGF-β1 concentration of 10.0 ng/mL was capable of stimulating DMP-1 and DSPP expression.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

A organização de fibras de colágeno no leito de uma ferida é componente importante da cicatrização e contração da ferida, determinando em última instância a qualidade final da cicatriz. Neste estudo realizamos a implantação de modelo de biotecnologia constituído de géis de colágeno povoados por fibroblastos humanos, que foi utilizado como instrumento para a melhor compreensão dos fenômenos ainda pouco elucidados, envolvidos na contração de feridas. Utilizando fibroblastos procedentes de pele normal ou quelóides, observou-se maior contração dos géis povoados por fibroblastos oriundos de quelóide. O modelo implementado foi considerado eficiente para a avaliação da presença de moduladores da fase de remodelação da cicatriz, tais como o Fator de Crescimento Transformador Beta (TGF beta). A comparação entre a curva de contração gerada por fibroblastos oriudos de pele normal sob o efeito do TGF beta e a contração gerada por fibroblastos de quelóides, demonstra que as mesmas apresentam comportamento igual do ponto de vista estatístico. O modelo proposto demonstrou ser adequado para a melhor compreensão dos mecanismos responsáveis pela contração de feridas, bem como possui potencial na avaliação de novas drogas capazes de modular este fenômeno / An important component of tissue healing and wound contraction is the re-arrangement of ground collagen fibers, which can ultimately influence the final quality of scars. In this study we used a biotechnology experimental model with contracting collagen gels seeded with human fibroblasts in order to better understand the phenomena involved in wound contraction. We compared the contraction of the collagen gels using fibroblasts from normal skin and from keloids, and we observed that the collagen gels seeded with keloid fibroblasts suffered a bigger contraction. The model was considered efficient to test growth factors with the potential to modulate the remodeling phase of the scar, for example, the Transforming Growth Factor Beta (TGF beta). The analysis of the changing macroscopic gel area comparing the contraction generated by the normal fibroblasts after the treatment with TGF beta with the contraction in the gels with keloid\'s fibroblasts showed that they have the same behavior. The experimental model proved to be an useful tool to better understand the wound contraction and to test new drugs to modulate this phenomenon.

Experimentelle FACS-Flow-Analysen im Kontext einer radiogenen Lungenfibrose zur Veränderung der Zellproliferation von Maus-Lungen-Fibroblasten unter dem Einfluss von Kulturüberständen bestrahlter Fibroblasten. Additiv einzelne Versuche mit Antikörperzugabe gegen TGF-beta zur Evaluation eines hemmenden Effektes auf eine postulierte Arretierung der Fibroblasten in der G1-Phase der Zellteilung durch die Zytokine der Kulturüberstände bestrahlter Maus-Lungen-Fibroblasten. / FACS-Flow-Analyses on changes of cell-proliferations of mouse-lung-fibroblasts under the influence of culture-supernatants of irradiated fibroblasts in the context of a radiogenic lung fibrosis. Additionally some studies on a postulated inhibitory effect of an tgf-beta-antibody on the g1-phase cell-cycle-arrest of mitosis through cytokines in the supernatants of the irradiated fibroblasts.

Der wesentliche Dosis limitierende Faktor einer Strahlentherapie thorakaler Malignome ist die Strahlenempfindlichkeit des Lungenparenchymes, da sich mit einer Häufigkeit von 25-75 % aller Patienten ein Strahlenschaden des Lungengewebes entwickeln kann. Die Inzidenz einer Lungenfibrose nach 6- 12 Monaten liegt bei 15-30%. Die Kombination zytostatischer Medikamente mit ionisierender Strahlung kann die Ansprechraten verbessern, kann andererseits die Inzidenz einer Pneumonitis erhöhen. Die konkreten Mechanismen, die zu einer Pneumonitis und einer strahleninduzierten Fibrose führen, sind bislang noch nicht vollständig bekannt. Es wird vermutet, daß die ortsständigen Zellen der Lunge eine aktivere Rolle in der Pathogenese als bisher angenommen, einnehmen. Tiermodelle der Strahlenschädiung der Lunge zeigten ein sehr frühe Expression von TGF-ß-mRNA and fibronectin-mRNA nach Bestrahlung. TGF-ß und Fibronectin sind in der BALF und Serum von an thorakalen Malignomen erkrankten, strahlentherapeutisch behandelten Patienten erhöht. Neben Makrophagen und Typ II Pneumocyten als zelluläre Quellen der genannten Cytokine, sind Fibroblasten in der Lage beide Agentien in erheblichem Umfang zu synthetisieren. Ziele Um die aktive Rolle von Fibroblasten in der Pathogenese der strahleninduzierten Lungenfibrose in Abwesenheit von Entzündungszellen zu untersuchen, bestrahlten wir Lungenfibroblasten in vitro und beobachteten folgende Parameter. 1. Zellwachstum 2. Synthese von Fibronectin 3. Synthese von Kollagen ( Procollagen-I-Peptid) 4. Synthese von TGF-ß1 Methoden Humane fetale Lungenfibroblasten (MRC-5 ,ICN Biochemicals Eschwege ,Deutschland) wurden in DME Medium kultiviert unter Zugabe von 10% FCS plus L-Glutamine, Penicillin G , Amphotericin B und Gentamycin; Luftfeuchtigkeit 100% , Temperatur 37°, CO2 5%, Medienwechsel erfolgten zweimal wöchentlich und 24 Stunden vor den Messungen. 24h nach der Aussaat der Zellen erfolgte die Strahlenapplikation (CO 60; 4.5, 7.5, 10.5 Gy ). Messungen erfolgten an den Tagen 3,6,9,12,15 nach Bestrahlung. Hierfür wurden folgende Materialien verwandt. Fibronectin (ELISA), Takara TGF beta (ELISA), DPC Biermann Procollagen-I-Peptide (ELISA), Takara LDH ( kinetischer Assay), Sigma Cell counts (Zählkammer) Alle Messungen wurden zweimal unternommen. Ergebnisse: 1. Das Zellwachstum wurde dosisabhängig gehemmt. 2. Beginnend am 3 Tag stieg die Syntheserate des Fibronectin dosisabhängig. 3. Ähnliche Beobachtungen wurde bzgl der Procollagen-I-Peptid Synthese beobachtet. 4. TGF-ß Spiegel fanden sich nach Bestrahlung ab Tag 6 bis zum 4-fachen über dem Ausgangswert erhöht und kehrten ziwschen den Tagen 9 und 15 auf das Ausgangsniveau zurück. 5. Eine Erhöhung des LDH wurde nicht beobachtet. Dies zeigte, dass eine Zytolyse kein wesentlichen Einfluß hatte. Disskusion: Bei Bestrahlung humaner fetaler Lungenfibroblasten wird das Zellwachstum dosisabhängig limitiert. Dies wurde nicht durch einen strahlenbedingt erhöhten Zelltod hervorgerufen , da das bestimmte LDH ( ein Marker der Zytolyse) in den Zellkulturüberständen nicht erhöht war. Wir vermuten, das durch Bestrahlung eine Differenzierung von Progenitor Fibroblasten zu postmitotischen Fibrocyten erfolgte, wie auch bereits von anderen Arbeitsgruppen berichtet. TGF-ß fand sich nach Bestrahlung in den Zellkulturüberständen deutlich erhöht. Es wird angenommen , daß TGF-ß eine Schlüsselrolle in der Pathogenese fibrosierender Erkrankungen der Lunge, der Leber, der Niere spielt und ebenso in die Enstehung der durch ionisierende Bestrahlung hervorgerufene Lungenfibrose eingebunden ist. Unsere Experimente haben gezeigt , daß Fibroblasten in der Lage sind große Mengen TGF-ß and Fibronectin - sogar in Abwesenheit von Entzündungszellen- zu erzeugen und sich vermutlich autokrin stimulieren können. Dieser Mechanismus wird als wichtiger Co-Faktor in der Pathobiologie verschiedener zur Fibrose führender Lungenerkrankungen angenommen. Schlussfolgerung Fibroblasten produzieren erhöhte Mengen TGF-ß und Fibronectin nach Applikation ionisierender Strahlung. Sie könnten in der Pathogenese der Strahlenschädigung der Lunge eine aktivere Rolle spielen als bisher angenommen. / Introduction The major dosis limiting factor of radiation therapy of thoracic malignomas is the lung which may develop radiation injury with a frequency of 25-70% of patients .The incidence of lung fibrosis after 6-12 months ist 15-30 %. Combination of cytostatic drugs with ionizid radiation can improve response rates, but may result in a higher incidence of pneumonitis. The exact mechanisms leading to pneumonitis and radiation induced fibrosis of the lung are yet unknown.The structural cells of the lung are of the lung are probably involved in the pathogenesis in a more active way than thougt until now. Animal models of radiation injury of the lung showed a very early expression of TGF-beta -mRNA and fibronectin-mRNA after irradiation. TGF-ß and Fibronectin were elevated in BALF and in serum. Macrophages and type-II-pneumocytes are thought to be the cellular source, but fibroblasts also are capable to synthesize both agents in large amounts. Aims In order to investigate the active role of fibroblasts in the pathogenesis of radiation fibrosis we irradiated human lung fibroblasts in vitro. We focused on following points: 1. cell growth 2. synthesis of fibronectin 3. synthesis of collagen (procollagen-I-peptid) 4. synthesis of TGF-beta-1 Methods Human fetal lung fibroblasts (MRC-5 ,ICN Biochemicals Eschwege ,Germany) cultured in DME-medium plus 10 % FCS plus L-glutamine, penicillin G, amphotericin B and gentamycine; air humidity 100 %, temp. 37°C, CO2 5%; change of medium twice weekly and 24 hr. before measurements. 24hrs. after seeding, application of ionizing radiation (CO 60; 4.5, 7.5, 10.5 Gy ). Measurements on day 3,6,9,12,15 after irradiation: Fibronectin (ELISA), Takara TGF beta (ELISA), DPC Biermann Procollagen-I-Peptide (ELISA), Takara LDH ( kinetic assay), Sigma Cell counts (counting chamber) All measurements have been done twice. Results 1. cell growth was inhibited in a dose dependent manner. 2. Beginning at day 3 cell related synthesis of fibronectin was increased depending on the dose of irradiation. 3. Similar observations were made in synthesis of procollagen-I-peptide. 4. TGF-beta levels were increased four fold after irradiation beginning on day 6 and returned to basal values between day 9 and 15 (the cells treated with 10.5 Gy were an exception. Here we found a furthermore higher secretion rate ). 5. No elevation of LDH was noticed, showing that cytolysis was not important in these effects. Discussion Irradiation of fetal human lung fibroblasts inihibited cell growth in a dose depend manner. This was not due to cell death initiated by ionizing rays, because LDH ( marker of cytolysis) was not elevated in culture supernatants. We assume that irradiation induces differentiation of progenitor-fibroblasts to promitotic fibrocytes as reported by other groups. TGF-beta was considerably elevated in culture supernatants after irradiation. TGF-beta is assumed to play a key role in fibrosing disease of lung, liver and kidney and may be involved in radiation induced lung fibrosis as well. Our experiments show, that fibroblasts are able to produce high amounts of TGF-beta and fibronectins - even if inflammatory cells are absent- and may stimulate themselves in an autocrine manner.This mechanism is thought to be an important co-factor in the pathobiology of different fibrosing disorders of the lung and may be important in radiation injury of the lung as well. Conclusion Fibroblasts produce increased amounts of TGF-beta and fibronectin after irradiation. They may play a more active role in the pathogenesis of radiation injury than thought up to now.

While TGF-β is able to regulate miRNA expression in numerous cell types, TGF-β-dependent changes in the miRNA profile of CD8+ T cells had not been studied before. Considering that TGF-β suppresses CD8+ T cell effector functions in numerous ways, we wondered whether induction of immune-regulatory miRNAs could add to the known transcriptional effects of TGF-β on immune effector molecules. In this study, we used miRNA arrays, deep sequencing and qRT-PCR to identify miRNAs that are modulated by TGF-β in human CD8+ T cells. Having found that the TGF-β-dependent downregulation of NKG2D surface expression in NK cells and CD8+ T cells does not go along with a corresponding reduction in mRNA levels, this pathway appeared to be a possible target of TGF-β-inducible miRNAs. However, this hypothesis could not be confirmed by miRNA reporter assays. Instead, we observed that DAP10 transcription is suppressed by TGF-β which in turn negatively affects NKG2D surface expression. In spite of promising preliminary experiments, technical difficulties associated with the transfection of primary NK cells and NK cell lines unfortunately precluded the final proof of this hypothesis. Instead, we focused on the TGF-β-induced changes in the miRNome of CD8+ T cells and confirmed the induction of the miR-23a cluster members, namely miR-23a, miR-27a and miR-24 by three different techniques. Searching for potential targets of these miRNAs which could contribute to the immunosuppressive action of TGF-β in T cells, we identified and confirmed a previously unknown regulation of IFN-γ mRNA by miR-27a and miR-24. Newly generated miRNA reporter constructs further revealed that LAMP1 mRNA is a target of miR-23a. Upon modulation of the miR-23a cluster in CD8+ T cells by the respective miRNA antagomirs and mimics, significant changes in IFN-γ expression confirmed the functional relevance of our findings. Effects on CD107a/LAMP1 expression were, in contrast, rather minimal. Still, overexpression of the miR-23a cluster attenuated the cytotoxic activity of antigen-specific CD8+ T cells. Taken together, these functional data reveal that the miR-23a cluster not only is induced by TGF-β, but also exerts a suppressive effect on CD8+ T-cell effector functions, even in the absence of TGF-β signaling. / Obwohl bekannt war, dass TGF- die miRNA Expression in zahlreichen Zelltypen moduliert, waren TGF- abhängige Veränderung des miRNA Profils in CD8+ T Zellen noch nicht untersucht worden. Da TGF-β die Effektorfunktionen von CD8+ T Zellen aber in vielfältiger Weise inhibiert, fragten wir uns, ob die transkriptionellen Effekte, die TGF-β bekanntermaßen auf Immuneffektormoleküle ausübt, noch durch die Induktion immunregulatorischer miRNAs ergänzt werden. Daher nutzten wir miRNA Arrays, Genomsequenzierungstechniken und Echtzeit-PCR um miRNAs zu identifizieren, welche in humane CD8+ T Zellen von TGF- moduliert werden. Die Beobachtung, dass die TGF--abhängige Herunterregulation der NKG2D Oberflächenexpression in Natürlichen Killerzellen und CD8+ T Zellen nicht mit einer entsprechenden Verringerung der mRNA Menge einhergeht, ließ zudem vermuten, dass dieser Signalweg über miRNAs reguliert werden könnte. Nach verschiedenen miRNA Reporterassays musste diese Hpothese jedoch verworfen werden. Stattdessen zeigte sich, dass TGF- die Transkription von DAP10 inhibiert was wiederum die Oberflächenexpression von NKG2D limitieren sollte. Trotz viel versprechender initialer Experimente scheiterte der letzgültige Beweis dieser Hypothese aber an der ungenügenden Transfizierbarkeit von primären NK Zellen sowie von NK Zelllinien. Daher konzentrierten wir uns im Weiteren auf die durch TGF- induzierten Veränderungen im miRNom von CD8+ T Zellen und konnten mit drei verschiedenen Techniken die Induktion des miR-23a Clusters (mit den einzelnen miRNAs miR-23a, miR-27a und miR-24) bestätigen. Auf der Suche nach potentiellen immunregulatorisch relevanten Zielgenen dieser miRNAs konnten wir erstmals eine Regulation von IFN- durch miR-27a und miR-24 nachweisen. Zu diesem Zweck generierte miRNA Reporterkonstrukte zeigten zudem, dass LAMP1 durch miR-23a reguliert wird. Nach Modulation des miR-23a Clusters durch die entsprechenden miRNA Antagomir und Surrogat-Konstrukte konnten wir auch in CD8+ T Zellen signifikante Veränderungen der IFN-γ Expression nachweisen und somit die funktionelle Relevanz unserer Befunde bestätigen. Die Effekte auf die Expression von CD107a/LAMP1 waren hingegen nur minimal. Trotzdem führte die Überexpression des miR-23a Clusters zu einer Verringerung der zytotoxischen Aktivität von antigenspezifischen CD8+ T Zellen. Zusammen genommen belegen diese funktionellen Untersuchungen, dass das miRNA-23a Cluster, welches durch TGF-β induziert wird, zur Hemung der Effektorfunktionen in CD8+ T Zellen beiträgt, und zwar sowohl in Gegenwart als auch in Abwesenheit von TGF-β.

Osteoarthritis (OA) is a debilitating condition affecting over 21 million persons in the United States. This number is expected to rise in the coming decades. Treatment approaches for OA focus on symptom modifying measures (i.e., pain relief) as disease modifying interventions do not currently exist. However, some of the interventions used to alleviate the symptoms of OA are also thought to have disease-modifying benefits. Two such non-surgical interventions for OA are intra-articular hyaluronan (HA) injections and physical exercise. In order to effectively study their effects in human OA, animal models that are amenable for studying intervention outcomes are needed. The research focused on developing and characterizing a progressive non-surgical model of knee OA in adult mice. This model was used to firstly, examine the capacity of intra-articular HA injections to prevent knee joint degeneration, and secondly to examine the capacity of moderate exercise to prevent onset and progression of joint degeneration. Intra-articular injections of TGF--β1 into murine knees produce synovial hyperplasia, osteophyte formation, and fibrotic changes on cartilage surfaces and joint capsules. However, additional exposure of the joints to high intensity treadmill running (biomechanical overuse) results in more widespread and focal OA-like cartilage erosions of both the tibial and femoral surfaces, similar to that described for the pathological appearance of late human knee OA. Taken together, these data support that synovitis and soft-tissue activation in early OA joints may precede and/or accelerate the process cartilage degeneration characteristic of progressive and late stage osteoarthritis. Intra-articular injections of high molecular weight HA one day following TGF--β1 injections resulted in decreased synovial hyperplasia, minimized osteophyte formation, and significantly decreased severity of cartilage lesions. A four week, alternate day, low intensity aerobic treadmill running program prior to TGF--β1 injections and overuse also resulted in decreased severity of cartilage lesions.

Endoglin, a co-receptor of the TGF-β superfamily, is predominantly expressed in endothelial cells and in some myeloid cells and implicated as a potential modulator of immune responses. We previously demonstrated that Endoglin heterozygous (Eng+/-) mice subjected to the dextran sulfate sodium colitis model developed persistent inflammation and epithelial ulceration, while Eng+/+ mice recovered following the acute phase of disease. Our aim was to assess potential alterations in distribution and number of immune cells, expression of inflammatory mediators and mechanisms of oxidative burst in Eng+/- mice. While the number of overall T, B and myeloid cells was unaltered between the genotypes, changes in neutrophil regulating cytokines and angiogenesis mediating factors were observed in Eng+/- mice. In addition, downregulation of phagocyte oxidative burst enzymes point to potential defects in microbial clearance in Eng+/- mice. These findings suggest a role for endoglin in regulating immune and vascular functions during inflammation.