@phdthesis{Schaefer2018,
  author    = {Sch{\"a}fer, Carmen},
  title     = {Influence of interleukin-6-type cytokine oncostatin M on murine aortic vascular smooth muscle cells},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-135527},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2018},
  abstract  = {Oncostatin M (OSM) is a cytokine of the interleukin-6 family and released in the early phase of inflammation by neutrophils, activated macrophages, dendritic cells, and T lymphocytes. Its roles in physiology and disease are not entirely understood yet. It has been shown recently that substantial amounts of OSM are found in atherosclerotic plaques. The first part of this thesis addresses the effects of OSM on vascular smooth muscle cells (VSMCs). This cell type is known to contribute to atherogenesis and expresses the type I and type II OSM receptor complexes. This study revealed that OSM is a strong inducer of an array of genes which have recently been shown to play important roles in atherosclerosis. Investigation of VSMCs isolated from OSMRbeta-deficient (Osmr-/-) mice proved that the regulation of these target genes is entirely dependent on the activation of the type II OSMR complex. In addition to OSM, other cytokines expressed by T lymphocytes were found to contribute to plaque development. According to earlier publications, the influence of IL-4, IL-13, and IL-17 on the progression of plaques were discussed controversially. Nevertheless, for the regulation of investigated atherosclerotic target genes and receptor complexes in VSMCs, they seemed to play a minor role compared to OSM. Only the expression of the decoy receptor IL-13Ralpha2 - a negative feedback mechanism for IL-13-mediated signalling - was strongly induced after treatment with all mentioned cytokines, especially when VSMCs were primed with OSM before stimulation. The second part of this thesis focuses on the role of OSM during the progression of atherosclerosis in vivo. Therefore, Ldlr-/-Osmr-/- mice were generated by crossing Ldlr-/- mice - a typical mouse model for atherosclerosis - with Osmr-/- mice. These double-deficient mice together with Ldlr-/-Osmr+/+ mice were set on cholesterol rich diet (Western diet, WD) for 12 weeks before they were sacrificed. Determination of body and organ weight, staining of aortas and aortic roots as well as gene expression profiling strongly suggested that Ldlr-/-Osmr-/- mice are less susceptible for plaque development and weight gain compared to Ldlr-/-Osmr+/+ mice. However, further experiments and additional controls (C57Bl/6 and Osmr-/- mice) on WD are necessary to clarify the underlying molecular mechanisms. Taken together, the interleukin-6-type cytokine OSM is a strong inducer of an array of target genes involved in de-differentiation and proliferation of VSMCs, a process known to contribute substantially to atherogenesis. Further in vivo studies will help to clarify the role of OSM in atherosclerosis.},
  subject      = {Arteriosklerose},
  language  = {en}
}
@phdthesis{Drechsler2012,
  author    = {Drechsler, Johannes},
  title     = {Determination of the hypertrophic potential of Oncostatin M on rat cardiac cells and the characterisation of the receptor complexes utilised by rat Oncostatin M},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-85215},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2012},
  abstract  = {Interleukin-6 (IL-6), oncostatin M (OSM), leukaemia inhibitory factor (LIF) and cardiotrophin-1 (CT-1) are members of the IL-6-type cytokine family that is characterised by sharing the common receptor subunit gp130. While the involvement of these polypeptides in cell differentiation, cell survival, proliferation, apoptosis, inflammation, haematopoiesis, immune response and acute phase reaction has already been demonstrated, the description of their role in development and progression of cardiac hypertrophy is still rather limited. A model has been postulated that declares the transient expression of IL-6-type cytokines as protective, while a continuous cardiac secretion of these proteins seems to be rather harmful for the heart. Within the first part of the study (results 4.1, 4.2 and 4.3) it was shown that OSM induces hypertrophy of primary neonatal rat cardiomyocytes (NRCM), just as its related cytokines LIF, CT-1 and hIL-6/hsIL-6R (hsIL-6R, human soluble IL-6 receptor). Regarding the hypertrophic potentials the LIFR/gp130 utilising cytokines (hLIF, hOSM and hCT-1) are stronger inducers than the OSMR/gp130 utilising mOSM. Human IL-6/hsIL-6R which signals via a gp130 homodimer has the weakest hypertrophic effect. The thorough analysis of typical signalling pathways initiated by IL-6-type cytokines revealed that STAT3 phosphorylation at Y705 seems to be the most important hypertrophy promoting pathway. In addition and in contrast to published work, we clearly demonstrate that classical IL-6 signalling (upon pure IL-6 treatment) has no hypertrophic effect on cardiomyocytes, because they lack sufficient amounts of the membrane-bound IL-6R. This is also true for neonatal rat cardiac fibroblasts (NRCFB). Since these cells can also influence cardiac hypertrophy, signalling pathways and target genes were additionally examined in NRCFB in response to OSM, LIF and IL-6/sIL-6R. One of the key findings of this thesis is the selective change in expression of cytokines and receptors of the IL-6 family in both cell types upon IL-6-type cytokine stimulation. A striking difference between NRCM and NRCFB is the fact that the target gene induction in NRCM is of similar duration upon mOSM and hIL-6/hsIL-6R treatment, while hIL-6/hsIL-6R is capable of promoting the induction of OSMR and IL-6 significantly longer in NRCFB. By searching for transcription factors or intermediate cytokines which could be responsible for this difference, a strong correlation between increased Il6 transcription and amount of mRNA levels for C/EBPβ and C/EBPδ was observed in response to IL-6/sIL-6R stimulation. Interestingly, mOSM also mediates the induction of C/EBPβ and δ, but the initiation is significantly less efficient than in response to IL-6/sIL-6R. Therefore, we assume that mOSM stimulation fails to reach threshold values required for a prolonged IL-6 secretion. Since we additionally observe a slight IL-6R mRNA upregulation in NRCFB, we assume that the combination of IL-6, LIF, C/EBPβ, C/EBPδ and IL-6R expression might be responsible for the observed different kinetics with which IL-6 and OSM stimulate NRCFB. In addition to the aforementioned proteins, members of the renin-angiotensin system seem to support the IL-6-type cytokine mediated hypertrophy. Since it has already been shown that angiotensin II vice versa induces IL-6 expression in NRCM and NRCFB, this enhanced expression of AT1α and ACE could be of crucial interest for the hypertrophy supporting phenotype. The second part of the presented work dealt with the characterisation of the receptor complexes of rat OSM. The central question of this analysis was, whether rOSM, just like mOSM, only binds the type II (OSMR/gp130) receptor complex or is able to utilise the type II and type I (LIFR/gp130) receptor complex. Using different experimental approaches (knock-down of the OSMR expression by RNA interference, blocking of the LIFR by LIF-05, an antagonistic LIF variant, and generation of stably transfected Ba/F3 cells expressing the newly cloned rat OSMR/gp130 or LIFR/gp130 receptor complex) we can clearly show that rat OSM surprisingly utilises both, the type I and type II receptor complex. Therefore it closely mimics the human situation. Furthermore, rOSM displays cross-species activities and stimulates cells of human as well as murine origin. Its signaling capacities closely mimic those of human OSM in cell types of different origin in the way that strong activation of the JAK/STAT, the MAP kinase as well as the PI3K/Akt pathways can be observed. Therefore, the results obtained in the last section of this thesis clearly suggest that rat disease models would allow evaluation of the relevance of OSM for human biology much better than murine models.},
  subject      = {Interleukin 6},
  language  = {en}
}