The development of fibrosis involves disruption of connective tissue homeostasis that may include inhibition of collagen remodeling pathways such as phagocytosis, as well as the differentiation of myofibroblasts, pro-fibrotic cells. Myofibroblast differentiation is dependent on actin assembly, which can alter cell shape and is required for collagen phagocytosis and remodeling. Cyclosporin A (CsA) is a commonly used drug for prevention of organ transplant rejection that causes marked fibrosis in periodontal tissues by inhibiting collagen phagocytosis. As gelsolin is a Ca2+-dependent actin severing protein that mediates collagen phagocytosis, I determined whether gelsolin is a CsA target. Compared to vehicle-treated controls, CsA-treatment of wild-type mice increased collagen accumulation by 60% in periodontal tissues; equivalent increases were seen in vehicle-treated gelsolin-null mice. From a series of in vitro experiments, I conclude that CsA-induced accumulation of collagen in the periodontal ECM involves disruption of the actin severing properties of gelsolin. This disruption inhibits the binding step of collagen phagocytosis and promotes fibrosis. During the development of pressure-induced cardiac hypertrophy, collagen accumulates in the interstitium, due to myofibroblasts which express alpha-smooth muscle actin (SMA). As focal adhesion complexes are putative mechanosensing organelles, I examined the role of focal adhesion kinase (FAK) and its interaction with gelsolin, in the regulation of SMA expression. After application of mechanical force to cultured fibroblasts through collagen-coated magnetite beads attached to beta1 integrins, FAK and gelsolin were recruited to beads and there was increased nuclear translocation of MRTF-A, a transcriptional co-activator of SMA. These data suggested a novel pathway in which mechanosensing by FAK regulates actin assembly through gelsolin; actin assembly in turn controls SMA expression through MRTF-A. I also examined a potential role for the actin nucleators, mammalian Diaphanous-related formins (mDia), in the mechanosensing pathway that leads to force-induced expression of SMA. siRNA knockdown of mDia inhibited actin assembly at force-induced focal adhesions. In anchored collagen gels to model myofibroblast-mediated contraction of the matrix, mDia knockdown reduced contraction by 50%. Collectively, these experiments indicate that the regulation of actin assembly plays an important role in the development of force-induced transcriptional activation of SMA, myofibroblast differentiation and collagen phagocytosis.

The development of fibrosis involves disruption of connective tissue homeostasis that may include inhibition of collagen remodeling pathways such as phagocytosis, as well as the differentiation of myofibroblasts, pro-fibrotic cells. Myofibroblast differentiation is dependent on actin assembly, which can alter cell shape and is required for collagen phagocytosis and remodeling. Cyclosporin A (CsA) is a commonly used drug for prevention of organ transplant rejection that causes marked fibrosis in periodontal tissues by inhibiting collagen phagocytosis. As gelsolin is a Ca2+-dependent actin severing protein that mediates collagen phagocytosis, I determined whether gelsolin is a CsA target. Compared to vehicle-treated controls, CsA-treatment of wild-type mice increased collagen accumulation by 60% in periodontal tissues; equivalent increases were seen in vehicle-treated gelsolin-null mice. From a series of in vitro experiments, I conclude that CsA-induced accumulation of collagen in the periodontal ECM involves disruption of the actin severing properties of gelsolin. This disruption inhibits the binding step of collagen phagocytosis and promotes fibrosis. During the development of pressure-induced cardiac hypertrophy, collagen accumulates in the interstitium, due to myofibroblasts which express alpha-smooth muscle actin (SMA). As focal adhesion complexes are putative mechanosensing organelles, I examined the role of focal adhesion kinase (FAK) and its interaction with gelsolin, in the regulation of SMA expression. After application of mechanical force to cultured fibroblasts through collagen-coated magnetite beads attached to beta1 integrins, FAK and gelsolin were recruited to beads and there was increased nuclear translocation of MRTF-A, a transcriptional co-activator of SMA. These data suggested a novel pathway in which mechanosensing by FAK regulates actin assembly through gelsolin; actin assembly in turn controls SMA expression through MRTF-A. I also examined a potential role for the actin nucleators, mammalian Diaphanous-related formins (mDia), in the mechanosensing pathway that leads to force-induced expression of SMA. siRNA knockdown of mDia inhibited actin assembly at force-induced focal adhesions. In anchored collagen gels to model myofibroblast-mediated contraction of the matrix, mDia knockdown reduced contraction by 50%. Collectively, these experiments indicate that the regulation of actin assembly plays an important role in the development of force-induced transcriptional activation of SMA, myofibroblast differentiation and collagen phagocytosis.

Mast cells (MC) are present in nearly all tissues in the body and participate in many physiological processes including allergy, tissue remodelling, fibrosis, angiogenesis, and autoimmunity. They can be activated by many stimuli, including allergic and innate immune stimulation. When activated, MC release mediators through which they can regulate inflammatory processes. Recently, we have discovered that rat and human MC express the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR), the gene responsible for Cystic Fibrosis (CF). We showed that CFTR had functional activity in MC and its expression was differentially regulated by IFNg. In this thesis, we compared CFTR expression between MC and epithelial cells (EC) by Western blot analysis and found that CFTR expression in MC is similar to that in EC, but there are some differences which suggest either glycosylation or post-transcriptional/translational differences between MC and EC. We also explored the role of CFTR in human MC secretion from various cellular compartments, in response to various stimuli. When we blocked CFTR using pharmacological inhibitors, there was an inhibition of cAMP-dependent Cl- flux. Our data also shows that CFTR pharmacological inhibition had no effect on IgE/anti-IgE-mediated b-hexosaminidase or eicosanoid release from MC. When we stimulated MC with either IgE/anti-IgE or the adenosine receptor agonist NECA (3 uM) for 24h in the presence of CFTR inhibitors, secretion of several mediators appeared to be dysregulated including IL-8, MIF, IL-13, IL-16, PAI-1 and CCL1. To add to these findings, we also used short hairpin RNA (shRNA) to reduce CFTR expression in MC. CFTR deficient MC were unresponsive to NECA and showed reduced constitutive IL-6 secretion. Finally, we cultured MC from CF and non-CF donor peripheral blood progenitors and compared several phenotypic and functional aspects of the cells. We saw no difference in growth, protease content and surface marker expression between CF and non-CF MC, but stimulation of the cells with IgE/anti-IgE or Pseudomonas aeruginosa appeared to differentially induce cytokine synthesis and secretion from CF and non-CF MC. These findings suggest that MC function is dysregulated in CF and that CF MC may be involved in the pathophysiology of CF. / Experimental Medicine

This thesis pertains to the pathogenesis of alcoholic pancreatitis, a considerable burden in terms of morbidity, mortality and health related costs. It has long been known that only a minority of alcoholics develop clinically evident pancreatitis, suggesting that (an) additional trigger factor(s) is required to elicit overt disease. Endotoxin (lipopolysaccharide LPS), from gut-derived gram negative bacteria may be one such trigger factor, since alcoholics exhibit increased levels of serum endotoxin. In addition, the degree of endotoxinaemia has been reported to correlate with the severity of pancreatitis. Studies described in this thesis report, i) the development of a novel rodent model of alcoholic pancreatitis produced by challenging alcohol-fed animals with single or repeated doses of LPS. The animals exhibit features of both acute (acinar vacuolisation, necrosis, pancreatic oedema, haemorrhage and inflammatory infiltration) and chronic (acinar atrophy and pancreatic fibrosis) pancreatitis; ii) the reversion of pancreatic injury (including fibrosis) upon withdrawal of alcohol in the model and the persistence of pancreatic damage with continuation of alcohol feeding; iii) activation of pancreatic stellate cells (PSCs, known to play a central role in fibrogenesis) in vivo and in vitro by alcohol and LPS; iv) the inhibition of PSC apoptosis in vivo and in vitro upon exposure to alcohol and LPS and the induction of PSC apoptosis in vivo upon withdrawal of alcohol from the diet and v) the presence of LPS receptors TLR4 and CD14 on PSCs, which would explain the responsiveness of PSCs to LPS. Thus the work in this thesis provides strong evidence in support of endotoxin as a clinically relevant trigger factor for the initiation of alcoholic pancreatitis and as a factor that promotes disease progression. The thesis also provides the first experimental evidence to support the clinical reports of a beneficial effect of abstinence on chronic pancreatitis. Delineation of the mechanisms mediating the induction, progression and reversibility of alcoholic pancreatitis has the potential to direct the development of new therapeutic interventions for alcohol-related pancreatic injury.

Age-dependent changes in the kidney are often debilitating, can be life-threatening and are a significant cause of increasing health costs worldwide. Excessive fibrosis, a general lack of regenerative ability and an increase in apoptosis in cells that determine healthy renal function work together to cause chronic kidney disease (CKD). This thesis reviewed the literature and then tested hypotheses developed from this review, to provide information on the molecules and mechanisms that determine the age-dependent changes of CKD. Results in this thesis provide a comprehensive analysis of the molecular, structural and functional changes of age-related CKD, with particular attention paid to the longevity gene p66Shc. The present studies were able to make use of established ageing rodent colonies of various phenotypes. In the first of the research Chapters, rat models of age-related CKD linked with obesity and hypertension were used. The research tested the hypothesis that each cause of age-related renal change (ageing, obesity or hypertension) would have differing underlying genetic modifications that could explain any differences in renal structure and function. In particular, alterations in oxidant handling and energy metabolism were investigated to identify markers for age-related CKD. Young (3 months) and old (20-24 months) spontaneously-hypertensive rats (SHR), normotensive Wistar- Kyoto (WKY) and Wistar rats (normotensive, with excess visceral and peri-renal fat in ageing) (N = 4 per group) were compared for renal functional and physiological parameters, fibrosis, inflammation and oxidative stress. All of the analyses indicated the old obese Wistars had the greatest renal injury, inflammation and markers of oxidative stress. In particular, % phosphop66/ p66Shc, considered an oxidant stress marker, was significantly increased in these animals (p<0.05). These results suggest that obesity and hypertension have differing oxidant handling and signalling pathways that act in the pathogenesis of age-related CKD, and that obesity alone may be a key causative mechanism of age-related CKD. x Oxidative stress is thought to be a major cause of age-related CKD. In chapter 5, the following hypotheses were tested: (1) that the added stress of ischemia-reperfusion (IR) injury on the ageing kidney would create an environment for increased injury; and (2) that this injury could be modulated by using a short-term anti-ageing strategies. Old (20-24 month) and young (3 month) WKY rats (females, N = 4 per group) were used to compare the effects of bilateral, 45-minute, IR injury with and without calorie restriction (a 40% reduction in food from baseline) or vitamin E (daily gavage of 1000IU) for 10 days prior to IR surgery and then for the length of recovery from IR (4 days). Histological, functional and molecular analyses were used. Old rats had significantly worsened renal injury compared with young rats with IR. Proteins involved in oxidative stress (HO-1, p66Shc and phospho-p66Shc), survival (PKB and phospho-PKB), apoptosis (Bax, Bcl-2), inflammation and fibrosis (NF-κB, tumour necrosis factor-α/TNFα, transforming growth factor-β/TGFβ) were differentially expressed according to age and development of IR injury. Vitamin E-supplemented animals showed minimal improvement and calorie restriction generally worsened the outcome in both young and old animals. Changes in protein expression support the notion that these short-term calorie-restricted animals were in a catabolic state, perhaps similar to protein energy wasting seen in some of the human dialysis population. In chapter 6 in vitro experimental models using primary human renal proximal tubular epithelial cells (PTECs) were utilised. Successive passaging in culture of the PTECs showed increasing markers of senescence and oxidative stress. The degree of senescence correlated with expression of the oxidative stress marker phospho-p66Shc and alterations in other key signalling molecules. Hydrogen peroxide (5mM for 1 hour) was used to simulate a burst of oxidative stress and the effects of leptin and resveratrol was examined. Histological and molecular analyses demonstrated some links with the previous in vivo results, for example the involvement of phospho-p66Shc in the development of cell senescence but generally the in vitro experiments did not replicate in vivo xi findings. The lack of complex, heterogeneous, cellular and growth factor/cytokine interactions of the in vivo environment are thought to be a factor in this disappointing result. The tendency for development of CKD differs in males and females in ageing humans. In chapter 7 characteristics of age-related CKD in old male and female rats were compared, summarising data on the WKY rats from Chapters 3 to 5. Minor differences between males and females in histology, function and protein expression are described, but these do not adequately reflect the findings of gender dimorphisms in development of CKD, reported from human and experimental in vivo studies. These experiments demonstrate some of the pathogenetic mechanisms of age-related CKD. The results indicate pathways or molecules that may be targeted in future therapies or may be used as biomarkers of early development of age-related CKD. In particular, the modification of p66Shc may one day be used to minimize renal damage and promote health in the elderly.

Thesis (Ph. D.)--Case Western Reserve University, 2008. / [School of Medicine] Department of Pharmacology. Includes bibliographical references.

Thesis (M.Med.Sc.)--University of Western Australia, 2007.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 78-89). Also available in electronic version.

Thesis (Ph. D.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on October 18, 2007) Vita. Includes bibliographical references.

Class of 2006 Abstract / Objectives: To develop a new equation to predict creatinine clearance specific for cystic fibrosis patients. Methods: A literature review was performed to capture data on the daily creatinine excretion in CF patients in relation to age, weight, height, and other physiologic variables. Nonlinear mixed effect modeling was then used to develop an equation to estimate creatinine clearance using individual covariates. The performance of the new equation developed was compared to the Cockcroft and Gault method in a CF population (age > 16 years). Results: A database of individual patient data from a previously published study of 19 patients was created. Significant covariates for model development included actual body weight, sex, and serum creatinine. The final candidate model was: 5.62× ABW0.67 CrCl = sCr(mg / dl) × 0.649( female) Conclusions: The results of the mean absolute error and root mean squared error calculations show that the new equation resulted in less bias and better precision than Cockcroft-Gault, Jeliffe I, and Jeliffe II based on the limited data available. However, these conclusions are limited in that the only evaluation data available was the same data that was used for model development.