Impact of fluoroquinolones and aminoglycosides on P. aeruginosa virulence factor production and cytotoxicity.

The opportunistic pathogen Pseudomonas aeruginosa is one of leading causes of disability and mortality worldwide and the world health organisation has listed it with the highest priority for the need of new antimicrobial therapies. P. aeruginosa strains responsible for the poorest clinical outcomes express either ExoS or ExoU, which are injected into target host cells via the type III secretion system (T3SS). ExoS is a bifunctional cytotoxin that promotes intracellular survival of invasive P. aeruginosa by preventing targeting of the bacteria to acidified intracellular compartments. ExoU is a phospholipase which causes destruction of host cell plasma membranes, leading to acute tissue damage and bacterial dissemination. Fluoroquinolones are usually employed as a first line of therapy as they have been shown to be more active against P. aeruginosain vitro than other antimicrobial classes. Their overuse over the past decade, however, has resulted in the emergence of antibiotic resistance. In certain clinical situations, aminoglycosides have been shown to be more effective then fluoroquinolones, despite their reduced potency towards P. aeruginosa in vitro. In this study, we evaluated the effects of fluoroquinolones (moxifloxacin and ciprofloxacin) and aminoglycosides (tobramycin and gentamycin) on T3SS expression and toxicity, in corneal epithelial cell infection models. We discovered that tobramycin disrupted T3SS expression and reduced both ExoS and ExoU mediated cytotoxicity, protecting infected HCE-t cells at concentrations below the minimal inhibitory concentration (MIC). The fluoroquinolones moxifloxacin and ciprofloxacin, however, upregulated the T3SS and did not inhibit and may have increased the cytotoxic effects of ExoS and ExoU

Neuropeptides and neurotransmitters in keratocytes : importance in corneal wound healing processes

Background: The cornea is the outermost transparent layer of the eye and it is responsible for the majorityof the eye’s total focusing power. Keratocytes are the resident cells of the corneal stroma and their function isto produce extracellular matrix components and to take part in corneal healing after injury, which may occurdue to trauma, infection or surgery. The process of corneal wound healing is complex. Shortly, keratocytesadjacent to the corneal wound undergo apoptosis and remaining cells start the process of proliferation andmigration in order to close the wound. Next, an influx of inflammatory cells such as macrophages andneutrophils occurs in order to clear the cornea from cellular debris. The final stage of the healing processrestores the quiescent state of keratocytes and remodels any disordered extracellular matrix components,leading to a healthy, transparent cornea. However, when the process of corneal wound healing is incompleteor disturbed, corneal scarring may occur, which can lead to significantly impaired vision. Despite extensiveresearch on corneal wound healing, corneal scarring remains a major cause of preventable blindness. Thehealing process is dependent on various cytokines and growth factors. However, it is possible that also othersignal substances are involved. Substance P (SP) is a neuropeptide well known for its role in pain perception.It has been shown that SP can also be produced by non-neuronal cells, including cells of the cornea, and thatit can have vast effects on physiological functions, including immune cell activity, and cellular processes, suchas cell migration, proliferation, and production of proinflammatory cytokines. Similarly, acetylcholine (ACh),a classical neurotransmitter, has also been reported to be produced by non-neuronal cells, including cornealepithelium, and to be involved in cell proliferation, angiogenesis, cell migration, apoptosis, and collagen geneexpression. In the studies of this thesis, it is hypothesized that neuropeptides and neurotransmitters areproduced by human keratocytes and that this production is increased in response to corneal injury. Moreover,it is hypothesized that the non-neuronal SP and ACh produced by injured keratocytes participate in cornealwound healing by enhancing keratocyte migration and proliferation, and/or by decreasing keratocyteapoptosis. The aims of this thesis project were to test these hypotheses and to study the underlying inter- andintracellular mechanisms of the effects of SP and ACh on keratocytes.Results: Cultured primary cells of the human corneal stroma expressed keratocyte markers (keratocan,lumican, CD34, and ALDH), the tachykinins SP and NKA, catecholamines (adrenaline, noradrenaline anddopamine), ACh, and glutamate. Moreover, the cells expressed neurokinin-1 and -2 receptors (NK-1R andNK-2R), dopamine receptor D2, muscarinic ACh receptors (mAChRs) M1, M3, M4 and M5, and NDMAR1glutamate receptor. Significant differences were observed between expression profiles in cultured keratocytesobtained from central and peripheral cornea. Such differences could also be seen between keratocytescultured under various serum concentrations. Expression and secretion of SP in cultured keratocytes wasincreased in response to injury in vitro. SP enhanced migration of cultured keratocytes through stimulation ofits preferred receptor, the NK-1R, and activation of the phosphatidylinositide 3-kinase and Rac1/RhoApathway and subsequent actin cytoskeleton reorganization and formation of focal adhesion points. Moreover,SP stimulation led to upregulated expression of the proinflammatory and chemotactic cytokine interleukin-8(IL-8), which also contributed significantly to SP-enhanced keratocyte migration and to attractingneutrophils. ACh enhanced keratocyte proliferation in vitro at low concentrations and this stimulation wasmediated through activation of mAChRs and activation of MAPK signalling. Moreover, ACh stimulation led toupregulation of two proliferation markers: PCNA and Ki-67. ACh was also able to protect cultured keratocytesfrom Fas-induced apoptosis, even at low concentrations. Activation of mAChRs was necessary for this latterprocess to occur. ACh reduced caspases 3/7 activation in Fas-treated keratocytes. Inhibition of the PKB/Aktpathway revealed that its activation is essential for mediating the anti-apoptotic effect of ACh in keratocytes.Conclusions: This thesis shows that human keratocytes express an array of neuropeptides (SP, NKA) andneurotransmitters (ACh, adrenaline, noradrenaline, dopamine and glutamate), and their receptors, and thatstimulation of NK-1R by SP and stimulation of mAChRs by ACh lead to keratocyte cellular processes that areknown to be involved in corneal wound healing. Specifically, SP enhances keratocyte migration throughupregulation of IL-8, ACh enhances keratocyte proliferation through activation of the MAPK signallingpathway, and ACh is able to protect keratocytes from apoptosis by activation of the PKB/Akt pathway. Takentogether, these findings suggest that both SP and ACh, if entered at the proper stage, could be beneficial forcorneal wound healing

Acetylcholine decreases formation of myofibroblasts and excessive extracellular matrix production in an in vitro human corneal fibrosis model

Acetylcholine (ACh) has been reported to play various physiological roles, including wound healing in the cornea. Here, we study the role of ACh in the transition of corneal fibroblasts into myofibroblasts, and in consequence its role in the onset of fibrosis, in an in vitro human corneal fibrosis model. Primary human keratocytes were obtained from healthy corneas. Vitamin C (VitC) and transforming growth factor-β1 (TGF-β1) were used to induce fibrosis in corneal fibroblasts. qRT-PCR and ELISA analyses showed that gene expression and production of collagen I, collagen III, collagen V, lumican, fibronectin (FN) and alpha-smooth muscle actin (α-SMA) were reduced by ACh in quiescent keratocytes. ACh treatment furthermore decreased gene expression and production of collagen I, collagen III, collagen V, lumican, FN and α-SMA during the transition of corneal fibroblasts into myofibroblasts, after induction of fibrotic process. ACh inhibited corneal fibroblasts from developing contractile activity during the process of fibrosis, as assessed with collagen gel contraction assay. Moreover, the effect of ACh was dependent on activation of muscarinic ACh receptors. These results show that ACh has an anti-fibrotic effect in an in vitro human corneal fibrosis model, as it negatively affects the transition of corneal fibroblasts into myofibroblasts. Therefore, ACh might play a role in the onset of fibrosis in the corneal stroma

Antiapoptotic Effect of Acetylcholine in Fas-Induced Apoptosis in Human Keratocytes

PURPOSE. To investigate the possible antiapoptotic effect of acetylcholine (ACh) in Fas-mediated apoptosis of primary human keratocytes in vitro, and to explore the underlying mechanism. METHODS. Primary human keratocytes were isolated from healthy corneas. Fas ligand (FasL) was used to induce apoptosis in keratocytes. Cell death was assessed by ELISA. Activity of caspase-3, -7, -8, and -9 was measured with luminescent caspase activity assays. Expression of nuclear factor-kappa B (NF-kappa B) gene was assessed with RT-quantitative (q)PCR. Cytochrome c release apoptosis assay kit was used to extract mitochondria and cytosol. Cytochrome c release, cleavage of Bid, and expression of B-cell lymphoma 2 (Bcl-2) were determined by Western blot. RESULTS. Cell death ELISA revealed that ACh is able to reduce Fas-induced apoptosis in keratocytes. Analysis of the activity of effector caspases-3 and -7 showed that ACh, when added to Fas-treated cells, decreases the activation of both these enzymes. The activity of initiator caspases -8 and -9 also decreased when ACh was added to Fas-treated cells. This antiapoptotic effect of ACh was dependent on ACh concentration and activation of muscarinic ACh receptors. Analysis of the antiapoptotic mechanisms triggered by ACh showed that ACh downregulates expression of FasL-induced NF-kappa B RNA expression, upregulates expression of antiapoptotic protein Bcl-2, downregulates expression of proapoptotic protein Bad, reduces cytochrome c release, and prevents proapoptotic Bid protein cleavage. CONCLUSIONS. Acetylcholine has an antiapoptotic effect in a Fas-apoptosis model of human primary keratocytes in vitro. It is therefore possible that ACh may play a role in corneal wound healing, by modulating its initiation phase

The adipose tissue stromal vascular fraction secretome enhances the proliferation but inhibits the differentiation of myoblasts

Background: Adipose tissue is an excellent source for isolation of stem cells for treating various clinical conditions including injuries to the neuromuscular system. Many previous studies have focused on differentiating these adipose stem cells (ASCs) towards a Schwann cell-like phenotype (dASCs), which can enhance axon regeneration and reduce muscle atrophy. However, the stromal vascular fraction (SVF), from which the ASCs are derived, also exerts broad regenerative potential and might provide a faster route to clinical translation of the cell therapies for treatment of neuromuscular disorders. Methods: The aim of this study was to establish the effects of SVF cells on the proliferation and differentiation of myoblasts using indirect co-culture experiments. A Growth Factor PCR Array was used to compare the secretomes of SVF and dASCs, and the downstream signaling pathways were investigated. Results: SVF cells, unlike culture-expanded dASCs, expressed and secreted hepatocyte growth factor (HGF) at concentrations sufficient to enhance the proliferation of myoblasts. Pharmacological inhibitor studies revealed that the signal is mediated via ERK1/2 phosphorylation and that the effect is significantly reduced by the addition of 100 pM Norleual, a specific HGF inhibitor. When myoblasts were differentiated into multinucleated myotubes, the SVF cells reduced the expression levels of fast-type myosin heavy chain (MyHC2) suggesting an inhibition of the differentiation process. Conclusions: In summary, this study shows the importance of HGF as a mediator of the SVF effects on myoblasts and provides further evidence for the importance of the secretome in cell therapy and regenerative medicine applications

Aniridia-related Keratopathy Relevant Cell Signaling Pathways in Human Fetal Corneas

We aimed to study aniridia-related keratopathy (ARK) relevant cell signaling pathways [Notch1, Wnt/β-catenin, Sonic hedgehog (SHH) and mTOR] in normal human fetal corneas compared with normal human adult corneas and ARK corneas. We found that fetal corneas at 20 weeks of gestation (wg) and normal adult corneas showed similar staining patterns for Notch1; however 10–11 wg fetal corneas showed increased presence of Notch1. Numb and Dlk1 had an enhanced presence in the fetal corneas compared with the adult corneas. Fetal corneas showed stronger immunolabeling with antibodies against β-catenin, Wnt5a, Wnt7a, Gli1, Hes1, p-rpS6, and mTOR when compared with the adult corneas. Gene expression of Notch1, Wnt5A, Wnt7A, β-catenin, Hes1, mTOR, and rps6 was higher in the 9–12 wg fetal corneas compared with adult corneas. The cell signaling pathway differences found between human fetal and adult corneas were similar to those previously found in ARK corneas with the exception of Notch1. Analogous profiles of cell signaling pathway activation between human fetal corneas and ARK corneas suggests that there is a less differentiated host milieu in ARK.Originally included in thesis in manuscript form.</p

Expression Profiles of Neuropeptides, Neurotransmitters, and Their Receptors in Human Keratocytes In Vitro and In Situ

Keratocytes, the quiescent cells of the corneal stroma, play a crucial role in corneal wound healing. Neuropeptides and neurotransmitters are usually associated with neuronal signaling, but have recently been shown to be produced also by non-neuronal cells and to be involved in many cellular processes. The aim of this study was to assess the endogenous intracellular and secreted levels of the neuropeptides substance P (SP) and neurokinin A (NKA), and of the neurotransmitters acetylcholine (ACh), catecholamines (adrenaline, noradrenaline and dopamine), and glutamate, as well as the expression profiles of their receptors, in human primary keratocytes in vitro and in keratocytes of human corneal tissue sections in situ. Cultured keratocytes expressed genes encoding for SP and NKA, and for catecholamine and glutamate synthesizing enzymes, as well as genes for neuropeptide, adrenergic and ACh (muscarinic) receptors. Keratocytes in culture produced SP, NKA, catecholamines, ACh, and glutamate, and expressed neurokinin-1 and -2 receptors (NK-1R and NK-2R), dopamine receptor D-2, muscarinic ACh receptors, and NDMAR1 glutamate receptor. Human corneal sections expressed SP, NKA, NK-1R, NK-2R, receptor D2, choline acetyl transferase (ChAT), M-3, M4 and M-5 muscarinic ACh receptors, glutamate, and NMDAR1, but not catecholamine synthesizing enzyme or the alpha(1) and beta(2) adrenoreceptors, nor M1 receptor. In addition, expression profiles assumed significant differences between keratocytes from the peripheral cornea as compared to those from the central cornea, as well as differences between keratocytes cultured under various serum concentrations. In conclusion, human keratocytes express an array of neuropeptides and neurotransmitters. The cells furthermore express receptors for neuropeptides/neurotransmitters, which suggests that they are susceptible to stimulation by these substances in the cornea, whether of neuronal or non-neuronal origin. As it has been shown that neuropeptides/neurotransmitters are involved in cell proliferation, migration, and angiogenesis, it is possible that they play a role in corneal wound healing

Antiangiogenic Arming of an Oncolytic Vaccinia Virus Enhances Antitumor Efficacy in Renal Cell Cancer Models▿ †

Oncolytic vaccinia viruses have shown compelling results in preclinical cancer models and promising preliminary safety and antitumor activity in early clinical trials. However, to facilitate systemic application it would be useful to improve tumor targeting and antitumor efficacy further. Here we report the generation of vvdd-VEGFR-1-Ig, a targeted and armed oncolytic vaccinia virus. Tumor targeting was achieved by deletion of genes for thymidine kinase and vaccinia virus growth factor, which are necessary for replication in normal but not in cancer cells. Given the high vascularization typical of kidney cancers, we armed the virus with the soluble vascular endothelial growth factor (VEGF) receptor 1 protein for an antiangiogenic effect. Systemic application of high doses of vvdd-VEGFR-1-Ig resulted in cytokine induction in an immunocompromised mouse model. Upon histopathological analysis, splenic extramedullary hematopoiesis was seen in all virus-injected mice and was more pronounced in the vvdd-VEGFR-1-Ig group. Analysis of the innate immune response after intravenous virus injection revealed high transient and dose-dependent cytokine elevations. When medium and low doses were used for intratumoral or intravenous injection, vvdd-VEGFR-1-Ig exhibited a stronger antitumor effect than the unarmed control. Furthermore, expression of VEGFR-1-Ig was confirmed, and a concurrent antiangiogenic effect was seen. In an immunocompetent model, systemic vvdd-VEGFR-1-Ig exhibited superior antitumor efficacy compared to the unarmed control virus. In conclusion, the targeted and armed vvdd-VEGFR-1-Ig has promising anticancer activity in renal cell cancer models. Extramedullary hematopoiesis may be a sensitive indicator of vaccinia virus effects in mice

Substance P induces fibrotic changes through activation of the RhoA/ROCK pathway in an in vitro human corneal fibrosis model

Fibrosis is characterized by hardening, overgrowth, and development of scars in various tissues as a result of faulty reparative processes, diseases, or chronic inflammation. During the fibrotic process in the corneal stroma of the eye, the resident cells called keratocytes differentiate into myofibroblasts, specialized contractile fibroblastic cells that produce excessive amounts of disorganized extracellular matrix (ECM) and pro-fibrotic components such as alpha-smooth muscle actin (alpha-SMA) and fibronectin. This study aimed to elucidate the role of substance P (SP), a neuropeptide that has been shown to be involved in corneal wound healing, in ECM production and fibrotic markers expression in quiescent human keratocytes, and during the onset of fibrosis in corneal fibroblasts, in an in vitro human corneal fibrosis model. We report that SP induces keratocyte contraction and upregulates gene expression of collagens I, III, and V, and fibrotic markers: alpha-SMA and fibronectin, in keratocytes. Using our in vitro human corneal fibrosis model, we show that SP enhances gene expression and secretion of collagens I, III, and V, and lumican. Moreover, SP upregulates gene expression and secretion of alpha-SMA and fibronectin, and increases contractility of corneal fibroblasts during the onset of fibrosis. Activation of the preferred SP receptor, the neurokinin-1 receptor (NK-1R), is necessary for the SP-induced pro-fibrotic changes. In addition, SP induces the pro-fibrotic changes through activation of the RhoA/ROCK pathway. Taken together, we show that SP has a pro-fibrotic effect in both quiescent human keratocytes and during the onset of fibrosis in an in vitro human corneal fibrosis model