Microbiological, environmental and proteolytic aspects in chronic rhinosinusitis with nasal polyposis

Chronic rhinosinusitis is one of the most common chronic respiratory tract diseases affecting up to 15% of the adult population in the Western world. It may be perpetuated by factors predisposing to sinus ostial obstruction together with inflammatory changes in the sinus mucosa. Chronic rhinosinusitis is associated with asthma, and it may represent the same disease process. Chronic rhinosinusitis with nasal polyposis (CRSwNP) and asthma share also the characteristic inflammatory features and histopathologic feature of airway remodelling. Remodelling is considered as a key event in the pathogenesis of asthma. It is controlled by a delicate balance between the matrix metalloproteinases (MMPs) and their regulators. The purpose of the present study was to evaluate the microbiological findings, inflammatory features and MMP and tissue inhibitor of metalloproteinases-1 (TIMP-1) expression in CRSwNP. The results were related to the patient history, exposure to moisture and clinical outcome in order to find out possible explanations for the etiology and chronicity of CRSwNP. Bacterial culture results were similar in patients and in controls and do not explain the chronic course of CRSwNP. The presence of fungi seems to be more common in CRSwNP than chronic rhinosinusitis in general, and they should be actively searched for using microbiological as well as histological methods. Typical outdoor fungal species were found in nasal lavage samples taken from controls in the autumn but not in the winter, reflecting environmental exposure. Exposure to moisture was reported by 46% of the CRSwNP patients, which is in accordance to the Finnish general population. Exposed patients did not differ significantly from non-exposed subjects with regards to microbiological findings, tissue eosinophilia and clinical outcome. Significantly elevated levels of collagenase-2 (MMP-8) and interleukin (IL)-8 but not tumour necrosis factor-α were found in CRSwNP patients. In particular, the activation of mesenchymal-type MMP-8 but not polymorphonuclear-type MMP-8 was associated with elevated IL-8 levels. IL-8 and MMP-8 may form an inductive cytokine-proteinase cascade in CRSwNP pathogenesis and provide a target for novel therapies and a diagnostic tool for monitoring CRSwNP treatment. The proteolytic spectrum is different in eosinophilic and non-eosinophilic CRSwNP with the up-regulation of MMP-8 and MMP-9 in non-eosinophilic CRSwNP, suggesting different pathophysiology in these subgroups. The lack of MMP up-regulation was associated with a poor prognostic factor and worse clinical outcome, representing a possible synergic anti-inflammatory function of MMP-8 and MMP-9 in CRSwNP. This study provides new information about possible immunologic mechanisms in the pathogenesis of CRSwNP. The recently discovered anti-inflammatory/ defensive properties of MMP-8 and MMP-9 in animal models are reported for the first time in a clinical setting in human inflammatory diseases.

Associations among Emdogain®, human oral carcinoma cells and oral proteolytic enzymes

The Enamel matrix derivative Emdogain® (EMD) is a commercially available tissue extract preparation of porcine enamel origin. Studies have shown EMD to be clinically useful in promoting periodontal regeneration. EMD has been widely used in periodontal therapy for over ten years, but the mechanism of its action and the exact composition are not completely clear. EMD is predominantly amelogenin (>90%). However, unlike amelogenin, EMD has a number of growth factor-like effects and it has been shown to enhance the proliferation, migration and other cellular functions of periodontal ligament fibroblasts and osteoblasts. In contrast, the effects of EMD on epithelial cell lines and in particular on oral malignant cells have not been adequately studied. In addition, EMD has effects on the production of cytokines by several oral cell lines and the product is in constant interaction with different oral enzymes. Regardless of the various unknown properties of EMD, it is said to be clinically safe in regenerative procedures, also in medically compromised patients. The aim of the study was to examine whether gingival crevicular fluid (GCF), which contains several different proteolysis enzymes, could degrade EMD and alter its biological functions. In addition, the objective was to study the effects of EMD on carcinogenesis-related factors, in particular MMPs, using in vitro and in vivo models. This study also aimed to contribute to the understanding of the composition of EMD. GCF was capable of degrading EMD, depending on the periodontal status, with markedly more degradation in all states of periodontal disease compared to healthy controls. EMD was observed to stimulate the migration of periodontal ligament fibroblasts (PLF), whereas EMD together with GCF could not stimulate this proliferation. In addition, recombinant amelogenin, the main component of EMD, decreased the migration of PLFs. A comparison of changes induced by EMD and TGF-β1 in the gene profiles of carcinoma cells showed TGF-β1 to regulate a greater number of genes than EMD. However, both of the study reagents enhanced the expression of MMP-10 and MMP-9. Furthermore, EMD was found to induce several factors closely related to carcinogenesis on gene, protein, cell and in vivo levels. EMD enhanced the production of MMP-2, MMP-9 and MMP-10 proteins by cultured carcinoma cells. In addition, EMD stimulated the migration and in vitro wound closure of carcinoma cells. EMD was also capable of promoting metastasis formation in mice. In conclusion, the diseased GCF, containing various proteases, causes degradation of EMD and decreased proliferation of PLFs. Thus, this in vitro study suggests that the regenerative effect of EMD may decrease due to proteases present in periodontal tissues during the inflammation and healing of the tissues in vivo. Furthermore, EMD was observed to enhance several carcinoma-related factors and in particular the production of MMPs by benign and malignant cell lines. These findings suggest that the clinical safety of EMD with regard to dysplastic mucosal lesions should be further investigated.

Characterization of cytokines, matrix metalloproteinases and toll-like receptors in human periodontal tissue destruction

Periodontal Disease affects the supporting structures of the teeth and is initiated by a microbial biofilm called dental plaque. Severity ranges from superficial inflammation of the gingiva (gingivitis) to extensive destruction of connective tissue and bone leading to tooth loss (periodontitis). In periodontitis the destruction of tissue is caused by a cascade of microbial and host factors together with proteolytic enzymes. Matrix metalloproteinases (MMPs) are known to be central mediators of the pathologic destruction in periodontitis. Initially plaque bacteria provide pathogen-associated molecular patterns (PAMPs) which are sensed by Toll-like receptors (TLRs), and initiate intracellular signaling cascades leading to host inflammation. Our aim was to characterize TNF-α (tumor necrosis factor-alpha) and its type I and II receptors in periodontal tissues, as well as, the effects of TNF-α, IL-1β (interleukin-1beta) and IL-17 on the production and/or activation of MMP-3, MMP-8 and MMP-9. Furthermore we mapped the TLRs in periodontal tissues and assessed how some of the PAMPs binding to the key TLRs found in periodontal tissues affect production of TNF-α and IL-1β by gingival epithelial cells with or without combination of IL-17. TNF-α and its receptors were detected in pericoronitis. Furthermore, increased expression of interleukin-1β and vascular cell adhesion molecule-1 was found as a biological indicator of TNF-α ligand-receptor interaction. MMP-3, -8, and 9 were investigated in periodontitis affected human gingival crevicular fluid and gingival fibroblasts produced pro-MMP-3. Following that, the effect of IL-17 was studied on MMP and pro-inflammatory cytokine production. IL-17 was increased in periodontitis and up-regulated IL-1β, TNF-α, MMP-1 and MMP-3. We continued by demonstrating TLRs in gingival tissues, in which significant differences between patients with periodontitis and healthy controls were found. Finally, enzyme-linked immunosorbent assays were performed to show that the gingival cells response to inflammatory responses in a TLR-dependent manner. Briefly, this thesis demonstrates that TLRs are present in periodontal tissues and present differences in periodontitis compared to healthy controls. The cells of gingival tissues respond to inflammatory process in a TLR-dependent manner by producing pro-inflammatory cytokines. During the destruction of periodontal tissues, the release (IL-1β and TNF-α) and co-operation with other pro-inflammatory cytokines (IL-17), which in turn increase the inflammation and thus be more harmful to the host with the increased presence of MMPs (MMP-1, MMP-3, MMP-8, MMP-9) in diseased over healthy sites.

Periodontitis and peri-implantitis biomarkers in human oral fluids and the null-allele mouse model

Tissue destruction associated with the periodontal disease progression is caused by a cascade of host and microbial factors and proteolytic enzymes. Aberrant laminin-332 (Ln-332), human beta defensin (hBD), and matrix metalloproteinase (MMP) functions have been found in oral inflammatory diseases. The null-allele mouse model appears as the next step in oral disease research. The MMP-8 knock-out mouse model allowed us to clarify the involvement of MMP-8 in vivo in oral and related inflammatory diseases where MMP-8 is suggested to play a key role in tissue destruction. The cleaved Ln-332 γ2-chain species has been implicated in the apical migration of sulcular epithelial cells during the formation of periodontal pockets. We demonstrated that increased Ln-332 fragment levels in gingival crevicular fluid (GCF) are strongly associated with the severity of inflammation in periodontitis. Porphyromonas gingivalis trypsin-like proteinase can cleave an intact Ln-332 γ2-chain into smaller fragments and eventually promote the formation of periodontal pockets. hBDs are components of an innate mucosal defense against pathogenic microbes. Our results suggest that P. gingivalis trypsin-like proteinase can degrade hBD and thus reduce the innate immune response. Elevated levels and the increased activity of MMPs have been detected in several pathological tissue-destructive conditions where MMPs are shown to cleave extracellular matrix (ECM) and basement membrane (BM) molecules and to facilitate tissue destruction. Elevated levels of MMP-8 have been reported in many inflammatory diseases. In periodontitis, MMP-8 levels in gingival crevicular fluid (GCF) and in peri-implant sulcular fluid (PISF) are elevated at sites of active inflammation, and the increased levels of MMP-8 are mainly responsible for collagenase activity, which leads to tissue destruction. MMP-25, expressed by neutrophils, is involved in inflammatory diseases and in ECM turnover. MMP-26 can degrade ECM components and serve as an activator of other MMP enzymes. We further confirmed that increased levels and activation of MMP-8, -25, and -26 in GCF, PISF, and inflamed gingival tissue are associated with the severity of periodontal/peri-implant inflammation. We evaluated the role of MMP-8 in P. gingivalis-induced periodontitis by comparing MMP-8 knock-out (MMP8-/-) and wild-type mice. Surprisingly, MMP-8 significantly attenuated P. gingivalis-induced site-specific alveolar bone loss. We also evaluated systemic changes in serum immunoglobulin and lipoprotein profiles among these mouse groups. P. gingivalis infection increased HDL/VLDL particle size in the MMP-8-/- mice, which is an indicator of lipoprotein responses during systemic inflammation. Serum total LPS and IgG antibody levels were enhanced in both mice groups. P. gingivalis-induced periodontitis, especially in MMP-8-/- mice, is associated with severe alveolar bone loss and with systemic inflammatory and lipoprotein changes that are likely to be involved in early atherosclerosis.

Geant4 Hadronic Cascade Models and CMS Data Analysis : Computational Challenges in the LHC era

This work belongs to the field of computational high-energy physics (HEP). The key methods used in this thesis work to meet the challenges raised by the Large Hadron Collider (LHC) era experiments are object-orientation with software engineering, Monte Carlo simulation, the computer technology of clusters, and artificial neural networks. The first aspect discussed is the development of hadronic cascade models, used for the accurate simulation of medium-energy hadron-nucleus reactions, up to 10 GeV. These models are typically needed in hadronic calorimeter studies and in the estimation of radiation backgrounds. Various applications outside HEP include the medical field (such as hadron treatment simulations), space science (satellite shielding), and nuclear physics (spallation studies). Validation results are presented for several significant improvements released in Geant4 simulation tool, and the significance of the new models for computing in the Large Hadron Collider era is estimated. In particular, we estimate the ability of the Bertini cascade to simulate Compact Muon Solenoid (CMS) hadron calorimeter HCAL. LHC test beam activity has a tightly coupled cycle of simulation-to-data analysis. Typically, a Geant4 computer experiment is used to understand test beam measurements. Thus an another aspect of this thesis is a description of studies related to developing new CMS H2 test beam data analysis tools and performing data analysis on the basis of CMS Monte Carlo events. These events have been simulated in detail using Geant4 physics models, full CMS detector description, and event reconstruction. Using the ROOT data analysis framework we have developed an offline ANN-based approach to tag b-jets associated with heavy neutral Higgs particles, and we show that this kind of NN methodology can be successfully used to separate the Higgs signal from the background in the CMS experiment.

Androgen receptor in transcriptional regulation and carcinogenesis

Androgens control a variety of developmental processes that create the male phenotype and are important for maintaining male fertility and normal functions of tissues and organs that are not directly involved in procreation. Androgen receptor (AR) that mediates the biological actions of androgens is a member of the nuclear receptor superfamily of ligand-inducible transcription factors. Although AR was cloned over 15 years ago, the mechanisms by which it regulates gene expression are not well understood. A growing body of in vitro experimental evidence suggests that a complex network of proteins is involved in the androgen-dependent transcriptional regulation. However, the process of AR-dependent transcriptional regulation under physiological conditions is largely elusive. In the present study, a series of experiments were performed, including quantitative chromatin immunoprecipitation (ChIP) assays, to investigate AR-mediated transcription process using living prostate cancer cells. Our results show that the loading of AR and recruitment of coactivators and RNA polymerase II (Pol II) to both the promoter and enhancer of AR target genes are a transient and cyclic event that in addition to hyperacetylation, also involves dynamic changes in methylation, phosphorylation of core histone H3 in androgen-treated LNCaP cells. The dynamics of testosterone (T)-induced loading of AR onto the proximal promoters of the genes clearly differed from that loaded onto the distal enhancers. Significantly, more holo-AR was loaded onto the enhancers than the promoters, but the principal Pol II transcription complex was assembled on the promoters. By contrast, the pure antiandrogen bicalutamide (CDX) complexed to AR elicited occupancy of the PSA promoter, but was unable to load onto the PSA enhancer and was incapable of recruiting Pol II, coactivators and following changes of covalent histone modifications. The partial antagonist cyproterone acetate (CPA) and mifepristone (RU486) were capable of promoting AR loading onto both the PSA promoter and enhancer at a comparable efficiency with androgen in LNCaP cells expressing mutant AR. However, CPA- and RU486-bound AR not only recruited Pol II and coactivator p300 and GRIP1 onto the promoter and enhancer, but also recruited the corepressor NCoR onto the promoter as efficiently as CDX. In addition, we demonstrate that both proteasome and protein kinases are implicated in AR-mediated transcription. Even though proteasome inhibitor MG132 and protein kinase inhibitor DRB (5, 6-Dichlorobenzimidazole riboside) can block ligand-dependent accumulation of PSA mRNA with same efficiency, their use results in different molecular profiles in terms of the formation of AR-mediated transcriptional complex. Collectively, these results indicate that transcriptional activation by AR is a complicated process, which includes transient loading of holo-AR and recruitment of Pol II and coregulators accompanied by a cascade of distinct covalent histone modifications; This process involves both the promoter and enhancer elements, as well as other general components of the cell machineries e.g. proteasome and protein kinase; The pure antiandrogen CDX and the partial antagonist CPA and RU486 exhibit clearly different profiles in terms of their ability to induce the formation of AR-dependent transcriptional complexes and the histone modifications associated with the target genes in human prostate cancer cells. Finally, by using quantitative RT-PCR to compare the expression of sixteen AR co-regulators in prostate cancer cell lines, xenografts, and clinical prostate cancer specimens we suggest that AR co-regulators protein inhibitor of activated STAT1 (PIAS1) and steroid receptor coactivator 1(SRC1) could be involved in the progression of prostate cancer.

Characterization of the mitochondrial active-site serine protein LACTB: filaments in the mitochondrial intermembrane space

Mitochondria have evolved from endosymbiotic alpha-proteobacteria. During the endosymbiotic process early eukaryotes dumped the major component of the bacterial cell wall, the peptidoglycan layer. Peptidoglycan is synthesized and maintained by active-site serine enzymes belonging to the penicillin-binding protein and the β-lactamase superfamily. Mammals harbor a protein named LACTB that shares sequence similarity with bacterial penicillin-binding proteins and β-lactamases. Since eukaryotes lack the synthesis machinery for peptidoglycan, the physiological role of LACTB is intriguing. Recently, LACTB has been validated in vivo to be causative for obesity, suggesting that LACTB is implicated in metabolic processes. The aim of this study was to investigate the phylogeny, structure, biochemistry and cell biology of LACTB in order to elucidate its physiological function. Phylogenetic analysis revealed that LACTB has evolved from penicillin binding-proteins present in the bacterial periplasmic space. A structural model of LACTB indicates that LACTB shares characteristic features common to all penicillin-binding proteins and β-lactamases. Recombinat LACTB protein expressed in E. coli was recovered in significant quantities. Biochemical and cell biology studies showed that LACTB is a soluble protein localized in the mitochondrial intermembrane space. Further analysis showed that LACTB preprotein underwent proteolytic processing disclosing an N-terminal tetrapeptide motif also found in a set of cell death-inducing proteins. Electron microscopy structural studies revealed that LACTB can polymerize to form stable filaments with lengths ranging from twenty to several hundred nanometers. These data suggest that LACTB filaments define a distinct microdomain in the intermembrane space. A possible role of LACTB filaments is proposed in the intramitochondrial membrane organization and microcompartmentation. The implications of these findings offer novel insight into the evolution of mitochondria. Further studies of the LACTB function might provide a tool to treat mitochondria-related metabolic diseases.

Milk casein-derived tripeptides : A special focus on blood pressure and vascular function

Increased consumption of low-fat milk products is inversely associated with the risk of hypertension. The beneficial effect of milk on blood pressure is attributed to high calcium and potassium content but also to specific peptide sequences, which are cleaved from milk protein during gastrointestinal digestion, fermentation of milk with proteolytic starter cultures or enzymatic hydrolysis. Milk products fermented with Lactobacillus helveticus contain casein-derived tripeptides isoleucine-proline-proline (Ile-Pro-Pro) and valine-proline-proline (Val-Pro-Pro), which have been shown to possess antihypertensive effects in humans and in experimental animals. The aim of the present series of studies was to investigate the effects of tripeptides Ile-Pro-Pro and Val-Pro-Pro or fermented milk products containing them on vascular function and blood pressure and to elucidate the mechanisms behind them by using different experimental models of hypertension. Another aim was to characterize the acute effects of tripeptides on blood pressure and arterial stiffness in mildly hypertensive humans. Ile-Pro-Pro and Val-Pro-Pro or fermented milk products containing them attenuated the development of hypertension in two experimental models of hypertension, spontaneously hypertensive rat (SHR) and type 2 diabetic Goto-Kakizaki (GK) rat fed with high-salt diet. Significant differences in systolic blood pressure (SBP) were seen after 8 weeks treatment with tripeptide-containing products compared to control product. Plant sterols did not enhance this effect. Two differently produced tripeptide powders produced a similar attenuating effect on SBP in SHR. In mildly hypertensive subjects, a single administration of tripeptide- and plant sterol-containing fermented milk product decreased both SBP and diastolic blood pressure (DBP) over a period of 8 hours. Protective effect of tripeptides Ile-Pro-Pro and Val-Pro-Pro and fermented milk products containing them on vascular function was demonstrated in in vitro studies and long-term experimental studies. The effect was shown to be endothelium-dependent and possibly involving endothelium-derived hyperpolarizing factor (EDHF). In the clinical study, single administration of tripeptide-containing fermented milk product did not affect measures of arterial stiffness. Long-term treatment with fermented milk product containing Ile-Pro-Pro and Val-Pro-Pro inhibited angiotensin-converting enzyme (ACE) and decreased aldosterone levels thus showing beneficial effects on the renin-angiotensin system (RAS) in SHR and GK. No changes in the components of RAS were observed by the single administration of the same product in mildly hypertensive subjects. Increased levels of cGMP, NOx and citrulline suggest increased nitric oxide (NO) production by the tripeptides. Taken together, Ile-Pro-Pro and Val-Pro-Pro -containing products attenuate the development of hypertension after long-term treatment in experimental models of hypertension and possess an acute antihypertensive effect in mildly hypertensive subjects. In addition, these tripeptides show endothelium-mediated beneficial effects on vascular function. Attenuation of blood pressure increase by the tripeptides in experimental animals involves RAS, but its role in the antihypertensive effect in humans remains to be elucidated.

Function and regulation of Cdk7

Understanding the process of cell division is crucial for modern cancer medicine due to the central role of uncontrolled cell division in this disease. Cancer involves unrestrained proliferation as a result of cells loosing normal control and being driven through the cell cycle, where they normally would be non-dividing or quiescent. Progression through the cell cycle is thought to be dependent on the sequential activation of cyclin-dependent kinases (Cdks). The full activation of Cdks requires the phosphorylation of a conserved residue (threonine-160 on human Cdk2) on the T-loop of the kinase domain. In metazoan species, a trimeric complex consisting of Cdk7, cyclin H and Mat1 has been suggested to be the T-loop kinase of several Cdks. In addition, Cdk7 have also been implicated in the regulation of transcription. Cdk7, cyclin H, and Mat1 can be found as subunits of general transcription factor TFIIH. Cdk7, in this context, phosphorylates the Carboxy-terminal domain (CTD) of the large subunit of RNA polymerase II (RNA pol II), specifically on serine-5 residues of the CTD repeat. The regulation of Cdk7 in these and other functions is not well known and the unambiguous characterization of the in vivo role of Cdk7 in both T-loop activation and CTD serine-5 phosphorylation has proved challenging. In this study, the fission yeast Cdk7-cyclin H homologous complex, Mcs6-Mcs2, is identified as the in vivo T-loop kinase of Cdk1(Cdc2). It also identifies multiple levels of regulation of Mcs6 kinase activity, i.e. association with Pmh1, a novel fission yeast protein that is the apparent homolog of metazoan Mat1, and T-loop phosphorylation of Mcs6, mediated by Csk1, a monomeric T-loop kinase with similarity to Cak1 of budding yeast. In addition, Skp1, a component of the SCF (Skp1-Cullin-F box protein) ubiquitin ligase is identified by its interactions with Mcs2 and Pmh1. The Skp1 association with Mcs2 and Pmh1 is however SCF independent and does not involve proteolytic degradation but may reflect a novel mechanism to modulate the activity or complex assembly of Mcs6. In addition to Cdk7, also Cdk8 has been shown to have CTD serine-5 kinase activity in vitro. Cdk8 is not essential in yeast but has been shown to function as a transcriptional regulator. The function of Cdk8 is unknown in flies and mammals. This prompted the investigation of murine Cdk8 and its potential role as a redundant CTD serine-5 kinase. We find that Cdk8 is required for development prior to implantation, at a time that is co-incident with a burst of Cdk8 expression during normal development. The results does not support a role of Cdk8 as a serine-5 CTD kinase in vivo but rather shows an unexpected requirement for Cdk8, early in mammalian development. The results presented in this thesis extends our current knowledge of the regulation of the cell cycle by characterizing the function of two distinct cell cycle regulating T-loop kinases, including the unambiguous identification of Mcs6, the fission yeast Cdk7 homolog, as the T-loop kinase of Cdk1. The results also indicate that the function of Mcs6 is conserved from fission yeast to human Cdk7 and suggests novel mechanisms by which the distinct functions of Cdk7 and Mcs6 could be regulated. These findings are important for our understanding of how progression of the cell cycle and proper transcription is controlled, during normal development and tissue homeostasis but also under condition where cells have escaped these control mechanisms e.g. cancer.

Studies on Matrix Metalloproteinase (MMP-2, -9 and -14) and β2 Integrin Targeting as Potential Anticancer Therapeutics

Proteolytic enzymes, such as matrix metalloproteinases (MMP), are associated to the progression of several cancers. They degrade extracellular components, which helps tumors to expand and cancer cells to escape from the primary site. Of all MMPs, gelatinases (MMP-2 and -9) and membrane type-1 matrix metalloproteinase (MT1-MMP, MMP-14), in particular, are often associated to more aggressive types of head and neck carcinomas as well as to a poorer outcome in patient survival. Although therapies during the last decades have advanced, the mortality of the disease is still rather high and adjuvant therapies are searched for continuously. MMP-9 and MT1-MMP are also involved in neo-angiogenesis, which is necessary for tumor expansion. For this reason, we have identified synthetic peptides-targeting gelatinases and MT1-MMP, and have also evaluated their anticancer effects in vitro and in vivo. Antigelatinolytic peptides effectively inhibited tongue-carcinoma cell invasion and reduced the growth of xenografted tumors. In tumor samples of mice that were treated with antigelatinolytic peptides, the micro-vessel density was significantly reduced. We also identified a novel MT1-MMP targeting peptide and demonstrated that it exerted anticancer effects against several malignant cell lines in vitro. The effects of MT1-MMP inhibition on tongue-squamous cell carcinomas were evaluated by using xenograft tumors, which it effectively inhibited. Tranexamic acid was also demonstrated to inhibit tongue-squamous cell carcinoma invasion, most probably due to its ability to prevent the plasmin-mediated activation of proMMP-9. Leukocyte β2 integrins are another interesting option when evaluating targets for the therapeutic intervention of inflammatory conditions or malignancies of hematopoietic origin, since β2 integrins are expressed mainly by leukocytes. We identified a novel technique for screening small-molecule libraries against β2 integrins, and by using this technique we identified a novel αMβ2 integrin-binding chemical (IMB-10). IMB-10 significantly enhances leukocyte adhesion and inhibits their motility. We also demonstrated that IMB-10 can be used to inhibit inflammation and lymphoma growth in vivo. Interestingly, IMB-10 also reduced leukocyte tumor infiltration and inhibited tumor invasion.

Growth differentiation factor 9 signalling in the ovary

In the ovary, two new members of the large TGF-beta superfamily of growth factors were discovered in the 1990s. The oocyte was shown to express two closely related growth factors that were named growth differentiation factor 9 (GDF-9) and growth differentiation factor 9B (GDF-9B). Both of these proteins are required for normal ovarian follicle development although their individual significance varies between species. GDF-9 and GDF-9B mRNAs are expressed in the human oocytes from the primary follicle stage onwards. This thesis project was aimed to define the signalling mechanisms utilized by the oocyte secreted GDF-9. We used primary cultures of human granulosa luteal cells (hGL) as our cell model, and recombinant adenovirus-mediated gene transfer in manipulating the TGF-b family signalling cascade molecules in these cells. Overexpression of the constitutively active forms of the seven type I receptors, the activin receptor-like kinases 1-7 (ALK1-7), using recombinant adenoviruses caused a specific activation of either the Smad1 or Smad2 pathway proteins depending on the ALK used. Activation of both Smad1 and Smad2 proteins also stimulated the expression of dimeric inhibin B protein in hGL cells. Treatment with recombinant GDF-9 protein induced the specific activation of the Smad2 pathway and stimulated the expression of inhibin betaB subunit mRNA as well as inhibin B protein secretion in our cell model. Recombinant GDF-9 also activated the Smad3-responsive CAGA-luciferase reported construct, and the GDF-9 response in hGL cells was markedly potentiated upon the overexpression of Alk5 by adenoviral gene transduction. Alk5 overexpression also enhanced the GDF-9 induced inhibin B secretion by these cells. Similarly, in a mouse teratocarcinoma cell line P19, GDF-9 could activate the Smad2/3 pathway, and overexpression of ALK5 in COS7 cells rendered them responsive to GDF-9. Furthermore, transfection of rat granulosa cells with small interfering RNA for ALK5 or overexpression of the inhibitory Smad7 resulted in dose-dependent suppression of GDF-9 effects. In conclusion, this thesis shows that both Smad1 and Smad2 pathways are involved in controlling the regulation of inhibin B secretion. Therefore, in addition to endocrine control of inhibin production by the pituitary gonadotropins, also local paracrine factors within in the ovary, like the oocyte-derived growth factors, may contribute to controlling inhibin secretion. This thesis shows as well that like other TGF-beta family ligands, also GDF-9 signalling is mediated by the canonical type I and type II receptors with serine/threonine kinase activity, and the intracellular transcription factors, the Smads. Although GDF-9 binds to the BMP type II receptor, its downstream actions are specifically mediated by the type I receptor, ALK5, and the Smad2 and Smad3 proteins.

Molecular Details of Serum Resistance of Yersinia enterocolitica

In complement activation, Factor H (FH) and C4b-binding protein (C4bp) are the key regulators that prevent the complement cascade from attacking host tissues. Some bacteria may bind and deposit these regulators on their own surfaces and thus provide themselves with an efficient means to avoid complement activation. In consequence, bacteria resist complement-mediated lysis and opsonin-dependent phagocytosis. This study has demonstrated that Y. enterocolitica, similar to many other pathogens, recruits both FH and C4bp to its surface to ensure protection against the complement-mediated killing. YadA and Ail, the most crucial serum resistance factors of Y.enterocolitica, mediate the binding of FH and C4bp. FH - YadA interaction involves multiple higher structural motifs on the YadA stalk and the short consensus repeats (SCRs) of the entire polypeptide chain of FH. The Ail binding site on FH has been located to SCRs 6 and 7. The binding site for FH on Ail, however, remains undetermined. Both YadA- and Ail-bound regulators display full cofactor activity for FI-mediated cleavage of C3b/C4b. FH/C4bp-binding characteristics do, however, differ between YadA and Ail. In addition, Ail captures the regulators only in the absence of blocking lipopolysaccharide O-antigen and outer core, whereas YadA binds FH/C4bp independent of the presence of other surface factors Independent of mode of binding, however, YadA and Ail provide Y. enterocolitica a means to avoid complement-mediated lysis, enhancing chances for the bacteria to survive in the host during various phases of infection.

Activator Protein-1 and Epidermal Growth Factor Receptor Interplay : In Vivo & In Vitro Studies

Critical cellular decisions such as should the cell proliferate, migrate or differentiate, are regulated by stimulatory signals from the extracellular environment, like growth factors. These signals are transformed to cellular responses through their binding to specific receptors present at the surface of the recipient cell. The epidermal growth factor receptor (EGF-R/ErbB) pathway plays key roles in governing these signals to intracellular events and cell-to-cell communication. The EGF-R forms a signaling network that participates in the specification of cell fate and coordinates cell proliferation. Ligand binding triggers receptor dimerization leading to the recruitment of kinases and adaptor proteins. This step simultaneously initiates multiple signal transduction pathways, which result in activation of transcription factors and other target proteins, leading to cellular alterations. It is known that mutations of EGF-R or in the components of these pathways, such as Ras and Raf, are commonly involved in human cancer. The four best characterized signaling pathways induced by EGF-R are the mitogen-activated protein kinase cascades (MAPKs), the lipid kinase phosphatidylinositol 3 kinase (PI3K), a group of transcription factors called Signal Transducers and Activator of Transcription (STAT), and the phospholipase Cγ; (PLCγ) pathways. The activation of each cascade culminates in kinase translocation to the nucleus to stimulate various transcription factors including activator protein 1 (AP-1). AP-1 family proteins are basic leucine zipper (bZIP) transcription factors that are implicated in the regulation of a variety of cellular processes (proliferation and survival, growth, differentiation, apoptosis, cell migration, transformation). Therefore, the regulation of AP-1 activity is critical for the decision of cell fate and their deregulated expression is widely associated with many types of cancers, such as breast and prostate cancers. The aims of this study were to characterize the roles of EGF-R signaling during normal development and malignant growth in vitro and in vivo using different cell lines and tissue samples. We show here that EGF-R regulates cell proliferation but is also required for regulation of AP-1 target gene expression in fibroblasts in a MAP-kinase mediated manner. Furthermore, EGF-R signaling is essential for enterocyte proliferation and migration during intestinal maturation. EGF-R signaling network, especially PI3-K-Akt pathway mediated AP-1 activity is involved in cellular survival in response to ionizing radiation. Taken together, these results elucidate the connection of EGF-R and AP-1 in various cellular contexts and show their importance in the regulation of cellular behaviour presenting new treatment cues for intestinal perforations and cancer therapy.