The disruption of the blood-brain barrier (BBB) occurs after ischemic and hemorrhagic stroke and contributes to secondary brain damage. Matrix metalloproteinase-9 (MMP9) has been identified to be the main mediator of post-stroke BBB disruption. It is unknown whether deposition of heme/iron in the brain following stroke would affect MMP9 expression. In this study, I have demonstrated that heme/iron up-regulated MMP9 expression in rat astrocytes and that this upregulation was most likely due to reactive oxygen species (ROS) generated by heme/iron deposition on cells. ROS can activate AP-1 and NFκB signaling pathways which were responsible for increased MMP9 expression. Inhibiting AP-1 and NFκB decreased MMP9 expression. Heme/iron deposition also activated Nrf-2 and increased the expression of neuroprotective heme oxygenase-1. My study suggests that heme and iron deposition generates ROS and increases MMP9 expression through AP-1 and NFκB signaling pathways and that targeting these pathways or clearance of heme and iron may modulate MMP9 expression for reduced damage.

Rheumatoid arthritis (RA) is a chronic, systemic inflammatory disorder that may affect many tissues and organs but principally attacks synovial joints. All the symptoms of RA are mainly caused by cell inflammation, which results in cellular infiltration and synovial hyperplasia, finally leading to severe bone erosion. Existing drugs (steroids, non-steroid antiinflammatory drugs, disease-modifying anti-rheumatic drugs, etc.) can attenuate the symptoms of RA; however, these drugs also have many side effects. Therefore, it is necessary to discover new drugs for RA. Excavatolide B (Exc-B) is derived from the gorgonian coral. In our preliminary observations, Exc-B strongly inhibited lipopolysaccharide (LPS)-induced proinflammatory inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expression in RAW264.7 macrophages. The present study also showed that Exc-B significantly attenuates the expressions of osteoclast-like gene, cathepsin K, and matrix metalloproteinase (MMP)-9 in LPS-treated RAW 264.7 cells. Moreover, in the adjuvant-induced RA animal model, Exc-B effectively reduced the swelling and arthritic index from the morphological viewpoint as well as reduced bone erosion and synovial hyperplasia from the pathological viewpoint. Our data indicates that Exc-B can inhibit disease progression in RA. Hence, Exc-B may serve as a useful therapeutic agent for the treatment of RA.

The disruption of the blood-brain barrier (BBB) occurs after ischemic and hemorrhagic stroke and contributes to secondary brain damage. Matrix metalloproteinase-9 (MMP9) has been identified to be the main mediator of post-stroke BBB disruption. It is unknown whether deposition of heme/iron in the brain following stroke would affect MMP9 expression. In this study, I have demonstrated that heme/iron up-regulated MMP9 expression in rat astrocytes and that this upregulation was most likely due to reactive oxygen species (ROS) generated by heme/iron deposition on cells. ROS can activate AP-1 and NFκB signaling pathways which were responsible for increased MMP9 expression. Inhibiting AP-1 and NFκB decreased MMP9 expression. Heme/iron deposition also activated Nrf-2 and increased the expression of neuroprotective heme oxygenase-1. My study suggests that heme and iron deposition generates ROS and increases MMP9 expression through AP-1 and NFκB signaling pathways and that targeting these pathways or clearance of heme and iron may modulate MMP9 expression for reduced damage.

The disruption of the blood-brain barrier (BBB) occurs after ischemic and hemorrhagic stroke and contributes to secondary brain damage. Matrix metalloproteinase-9 (MMP9) has been identified to be the main mediator of post-stroke BBB disruption. It is unknown whether deposition of heme/iron in the brain following stroke would affect MMP9 expression. In this study, I have demonstrated that heme/iron up-regulated MMP9 expression in rat astrocytes and that this upregulation was most likely due to reactive oxygen species (ROS) generated by heme/iron deposition on cells. ROS can activate AP-1 and NFκB signaling pathways which were responsible for increased MMP9 expression. Inhibiting AP-1 and NFκB decreased MMP9 expression. Heme/iron deposition also activated Nrf-2 and increased the expression of neuroprotective heme oxygenase-1. My study suggests that heme and iron deposition generates ROS and increases MMP9 expression through AP-1 and NFκB signaling pathways and that targeting these pathways or clearance of heme and iron may modulate MMP9 expression for reduced damage.

The Metzincins are a superfamily of zinc-dependent endopeptidases associated with the regulation of the extracellular matrix (ECM). Their members include A Disintegrin and Metalloproteinase with Thrombospondin Motifs (ADAMTSs), A Disintegrin and Metalloproteinases (ADAMs), and the matrix metalloproteinases (MMPs). Metzincins exhibit diverse functions associated with both physiological and pathological states that include the proteolytic degradation of the ECM, regulation of various growth factors, cell surface receptors, and chemokines, and mediation of biological functions such as extravasation, survival, and proliferation. In pathological conditions such as cancer associated with chronic inflammation and multiple sclerosis associated with neurodegeneration, dysregulation of Metzincin activities are a hallmark of disease progression and severity. Hence, Metzincins are therapeutic targets for various disease states and research into optimal Metzincin inhibitor design is an ongoing exploit. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

No / Hair follicle (HF) morphogenesis is governed by a series of signals exchanged between the epidermal keratinocytes committed to HF-specific differentiation and the mesenchymal cells forming the follicular papilla (Schmidt-Ullrich and Paus, 2005). These interactions lead to the construction of the hair bulb, in which keratinocytes rapidly proliferate and differentiate into several cell populations forming the hair shaft and the inner root sheath. During the final steps of development, the HF elongates up to its maximal length and the hair shaft emerges through the epidermis through the hair canal that is formed at the distal portion of the HF epithelium (Schmidt-Ullrich and Paus, 2005). ...To elucidate a role for MMP-9 in the control of HF development and hair canal formation, its expression was studied by immunohistochemistry in cryosections of embryonic and postnatal skin of C57BL/6 mice (Sharov et al., 2003), and was correlated to the micro-anatomy of the developing hair canal depicted by high-resolution light microscopy, as described previously (Magerl et al., 2001). MMP-9 expression was not observed in the epidermis and developing HF placodes.

Thesis (Ph.D.)--University of Alabama at Birmingham, 2008. / Title from PDF title page (viewed on Sept. 17, 2009). Includes bibliographical references.

Mammals cannot re-form heavily damaged bones as in large fracture gaps, whereas zebrafish efficiently regenerate bones even after amputation of appendages. However, the source of osteoblasts that mediate appendage regeneration is controversial. Several studies in zebrafish have shown that osteoblasts are generated by dedifferentiation of existing osteoblasts at injured sites, but other observations suggest that de novo production of osteoblasts also occurs. In this study, we found from cell-lineage tracing and ablation experiments that a group of cells reserved in niches serves as osteoblast progenitor cells (OPCs) and has a significant role in fin ray regeneration. Besides regeneration, OPCs also supply osteoblasts for normal bone maintenance. We further showed that OPCs are derived from embryonic somites, as is the case with embryonic osteoblasts, and are replenished from mesenchymal precursors in adult zebrafish. Our findings reveal that reserved progenitors are a significant and complementary source of osteoblasts for zebrafish bone regeneration.

Patients with cystic fibrosis who are infected with the pathogen Pseudomonas aeruginosa have shown favorable responses to the drug azithromycin (AZM). This drug works in an anti-inflammatory capacity, improving clinical outcomes and improving quality of life in this population. The drug has also been shown to affect macrophage polarization by shifting these cells away from an inflammatory phenotype toward an alternatively activated anti-inflammatory phenotype. The full impact of this phenotypic change is not well understood in the context of the response to P. aeruginosa infection, or the overall immune response in cystic fibrosis. To understand how the AZM-polarized macrophage affects other types of cells, we utilized a co-culture in vitro system, with macrophages and fibroblasts incubating together. In this system, we determined that AZM causes upregulation of the pro-fibrotic mediator transforming growth factor-β as well as the extracellular matrix (ECM) protein fibronectin. The mediator of ECM turnover, matrix metalloproteinase (MMP)-9 was upregulated in this system as well. In an in vivo model of P. aeruginosa infection, MMP- 9 and fibronectin were increased in the bronchoalveolar lavage 7 days post-infection in mice that were treated with AZM. This was accompanied by a decrease in damage to the lung tissue, determine by histological examination. To determine if these changes would continue in human subjects with cystic fibrosis, a clinical study was done in this population. Subjects with AZM treatment had decreased TGF-β levels, but no differences in MMP-9 or fibronectin. Interestingly, correlations between certain fibrotic mediators and inflammatory cytokines, specifically interleukin -1β, were different in subjects with AZM treatment compared to subjects without AZM therapy. Together, these data indicate that AZM alters the fibrotic response from the macrophages, as well as the interaction of the inflammatory response and fibrosis development.

Traumatic brain injury (TBI) is a serious health concern, causing cognitive, motor, and sensory deficits, including olfactory dysfunction. This dissertation explores the effects of TBI on synaptic plasticity within the olfactory system, seeking to define mechanisms guiding postinjury sensory reinnervation. Physical forces induced by TBI can axotomize olfactory receptor neurons (ORNs), which innervate olfactory bulb (OB). These axons regenerate OB projections after injury, a process involving growth through a complex extracellular matrix (ECM). As such, we investigated a potential molecular mechanism capable of modifying local OB ECM to support postinjury synaptogenesis. Since matrix metalloproteinases (MMPs) and their ECM substrates are recognized for TBI therapeutic potential, we explored the role of MMP9 and its substrate osteopontin (OPN) in promoting ORN reinnervation of the OB after mild fluid percussion injury (FPI). First, we confirmed that FPI deafferented the mouse OB. In Chapter 2, we showed concurrent activation of neuroglia, elevated spectrin proteolysis and reduction in ORN-specific olfactory marker protein (OMP). As OMP normalized during regeneration, growth associated protein-43kD (GAP-43) peaked, marking OB entry of ORN growth cones. Ultrastructural analysis revealed ongoing ORN axon shrinkage and degeneration, glial phagocytosis of cellular debris, and a reorganization of synaptic structure. To explore ECM role in mediating postinjury OB reinnervation, we defined the time course of MMP9 activity and several downstream targets. Chapter 3 reports biphasic MMP9 activity increase during acute/subacute degeneration, accompanied by robust generation of 48kD OPN cell signaling peptide. OPN receptor CD44 also increased during the acute/subacute interval, suggesting potential interaction of the two proteins. Finally, we utilized MMP9 knockout (MMP9KO) mice to confirm MMP9 role in OB synaptogenesis. In Chapter 4, MMP9KO reversed FPI-induced lysis of 49kD OPN and altered postinjury expression of ORN axon degeneration marker OMP. Additional ultrastructural analysis verified delayed recovery of OB synaptic features within the injured MMP9KO. Overall, we demonstrated that mild FPI elicits ORN axotomy to induce OB reactive synaptogenesis, and that MMP9 supports reinnervation by processing OPN for activation of local glia, cells which reorganize the ECM for synapse regeneration.