No description available.

Keloids are classically regarded as scars that `outgrow the boundary of the original injury'. Ambiguous data concerning certain characteristics of keloid fibroblasts (such as proliferation rates and collagen production), however, have served only to confuse researchersT. he lack of an in vivo model and of detailed clinical accounts are added problems. In this study, a murine granulomatous tissue resolution model was used to investigate the profile of a number of cytokines suspectedto be involved in the aetiology of keloids. The results obtained from these experiments were then extrapolated to clarify the observations made in keloids. The results of these extrapolated comparisons revealed elevated levels of interleukin (IL)-4, IL-10, vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF) and transforming growth factor beta (TGF)-ß in keloid samples and decreasedle vels of interferon (IFN)-y and IL-2. The murine model was also used to investigate the implications of the low levels of IFN-y known to be present in the serum of keloid patients and shown here to be present in clinical samples. The results were found to support the hypothesis that the addition of IFN-y reduces the fibrosis so typical of keloids by rectifying the abnormality of the absence of IFNy content. The same model was used to provide evidence that the inhibition of VEGF activity in resolving wounds may halt the development of keloid lesions. The immunohistochemical profiles of cellular proliferation, apoptosis, lymphokines and cytokines for resolution (and, to a certain extent, the model) were used to compare with the abnormally resolved wounds which were available as clinical samples. Immunohistochemistry was also employed to describe the cellular nature of the clinical tissue samples in detail and to facilitate the development of the following hypothesis for keloid formation and propagation: lymphocytes migrate to the site of an (alleged) endogenous antigen present in the skin. The nature of these lymphocytes is characteristic of a type 2 immune response, they produce IL-4 (and IL-10) which in turn inhibit(s) the production of IFN-y and IL-2. Aside from this immunological response, wound resolution is taking place: fibroblasts are producing PDGF, EGF and TGF-ß to aid matrix remodelling and collagen synthesis. The provisional matrix is being vascularised by the action of VEGF, to allow the replenishment of nutrients; regression of blood vessels occurs through the action of an apoptosis-dependent mechanism, as does the 'normalisation' of fibroblastic populations. The keloid scar continues to grow after the cessation of resolution because the immune response to the 'endogenous' antigen continues and the lymphocytes continue to migrate to the site of the wound and continue to stimulate fibroblast proliferation and collagen production through the release of IL-4.

Multiple Sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) that is characterized by widespread focal areas of inflammation and demyelination. Although the exact cause of the disease is still not known, myelin-reactive T cells that enter the CNS trigger the disease and lead to the recruitment and activation of macrophages and other immune cells. One set of candidates that could serve to mediate these CNS changes is the family of phospholipase A2 (PLA2) enzymes, which consist of secreted (sPLA2) and cytosolic (cPLA2) forms. These enzymes hydrolyze membrane phospholipids to release free fatty acids (arachidonic acid) that can stimulate complex inflammatory cascades, and lysophospholipids that can induce myelin breakdown and demyelination, the two pathological hallmarks of MS. / For my Ph.D. research I studied the expression and role of different members of the PLA2 family in 'experimental autoimmune encephalomyelitis' (EAE), a widely used animal model of MS. I first generated a relapsing-remitting form of EAE in the C57BL/6 mouse strain that lacks a major form of sPLA2. I showed that cPLA2 is expressed by immune cells in the EAE lesions in the CNS. Furthermore blocking the activity of cPLA2 with a broad-spectrum chemical inhibitor starting at the time of EAE induction reduced the incidence and severity of disease, reduced lesion burden as well as reduced the expression of a number of chemokines and cytokines. Treating mice in the remission phase also prevented further clinical episodes. This showed that some or all members of the cPLA2 family play an important role in the onset and progression of EAE in a strain of mice lacking sPLA2. / I next carried out studies to assess the expression of all 14 members of the sPLA2 and cPLA2 families at the onset, peak and remission stages of EAE in the SJL/J mouse strain that expresses all forms of PLA2. The mRNA expression of only 4 of these PLA2s was increased. These include sPLA2 (groups IIA and V) and cPLA 2 (groups IVA and VIA). The expression of these PLA2s in the CNS was also characterized by double-immunofluorescence. The role of these PLA2s was assessed using selective inhibitors and analysed by monitoring the clinical disability scores, chemokine/cytokine protein arrays, lipomics lipid profiling, and histological analysis. Surprisingly, the sPLA2 inhibitor prevented disease remission and worsened the clinical outcome. This was accompanied by an increase in several pro-inflammatory chemokines. Selective inhibitors of cPLA2 group IVA and the calcium independent foam group VIA (iPLA2) reduced severity of EAE when given starting before onset of disease. The cPLA2 inhibitor treatment was effective only while administered, while iPLA2 inhibitor treatment was effective even after treatment was stopped. Furthermore, only delayed treatment with the iPLA2 inhibitor was effective, suggesting that cPLA2 group IVA only plays a role in the initiation of disease, while iPLA 2 plays a role in both disease onset and progression. These effects were also associated with concomitant reduction in chemokine/cytokine expression, reduction of inflammatory lipid mediators, and increase in protective lipids e.g., omega 3 fatty acids. / This work has allowed us to dissect out the expression and role of different members of the PLA2 family and has revealed the importance of selectively inhibiting some but not others in EAE. These findings may therefore have important implications for the treatment of MS.

No description available.

Inflammation of the central nervous system (CNS) is important in many human diseases, and is regulated by a multitude of factors, including the cytokine interferon-gamma (IFNgamma). The importance of IFNgamma is highlighted in experimental autoimmune encephalomyelitis (EAE), an animal model of CNS inflammation. Mice lacking IFNgamma show exaggerated disease, with a different pattern of chemokine expression than the wild-type. We administered IFNgamma to the CNS using intrathecal injection of a replication-defective adenoviral vector to ask about direct actions of IFNgamma on chemokine expression without the confounding factors present during CNS inflammation. AdIFNgamma induced expression of CXCL10 and CCL5, two chemokines strikingly absent in Ifng-/- EAE. Chemokine expression was not associated with inflammation, though when an infectious stimulus was administered, an influx of immune cells to the CNS was seen. Using AdIFNgamma to restore IFNgamma to Ifng-/- mice with EAE had a disease-limiting effect. We used vectors encoding CXCL10 or CCL5, to replace these chemokines which are absent during Ifng-/- EAE, attempting to modulate the disease into a form resembling that of the wild-type. AdCCL5 treatment showed a mild reduction in EAE severity in the Ifng-/-, though AdCXCL10 treatment had no effect. A principal inducer of IFNgamma is interleukin-18 (IL 18), and IFNgamma induces IL18-binding protein (IL18bp) which inhibits IL18, establishing a negative feedback loop. We found that ILl8bp expression is upregulated in wild-type mice with EAE, but not in the Ifng-/-, suggesting that the exaggerated disease of the Ifng -/- may be due in part to unrestrained actions of ILI8. Treatment with a vector encoding IL18bp (AdIL18bp) significantly inhibited EAE, without restricting immune cell entry to the CNS. Cytokine expression was shifted away from a pattern favouring Th17 development. AdIL18bp treatment inhibited EAE in Ifng-/- mice, indicating that IFNgamma was not required for this activity. We used a vector encoding M3, a chemokine-binding protein derived from MHV-68, to reduce EAE severity, showing the first use of a viral chemokine-binding protein in EAE.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21617号 / 医博第4423号 / 新制||医||1033(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 羽賀 博典, 教授 川口 義弥, 教授 妹尾 浩 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

No description available.