Aerosol delivery of star polymer-siRNA nanoparticles as a therapeutic strategy to inhibit lung tumor growth.

Lung cancer is a major contributor to cancer-related death worldwide. siRNA nanomedicines are powerful tools for cancer therapeutics. However, there are challenges to overcome to increase siRNA delivery to solid tumors, including penetration of nanoparticles into a complex microenvironment following systemic delivery while avoiding rapid clearance by the reticuloendothelial system, and limited siRNA release from endosomes once inside the cell. Here we characterized cell uptake, intracellular trafficking, and gene silencing activity of miktoarm star polymer (PDMAEMA-POEGMA) nanoparticles (star nanoparticles) complexed to siRNA in lung cancer cells. We investigated the potential of nebulized star-siRNA nanoparticles to accumulate into orthotopic mouse lung tumors to inhibit expression of two genes [ßIII-tubulin, Polo-Like Kinase 1 (PLK1)] which: 1) are upregulated in lung cancer cells; 2) promote tumor growth; and 3) are difficult to inhibit using chemical drugs. Star-siRNA nanoparticles internalized into lung cancer cells and escaped the endo-lysosomal pathway to inhibit target gene expression in lung cancer cells in vitro. Nebulized star-siRNA nanoparticles accumulated into lungs and silenced the expression of ßIII-tubulin and PLK1 in mouse lung tumors, delaying aggressive tumor growth. These results demonstrate a proof-of-concept for aerosol delivery of star-siRNA nanoparticles as a novel therapeutic strategy to inhibit lung tumor growth.

Delineating the Role of ßIV-Tubulins in Pancreatic Cancer: ßIVb-Tubulin Inhibition Sensitizes Pancreatic Cancer Cells to Vinca Alkaloids.

Pancreatic cancer (PC) is a lethal disease which is characterized by chemoresistance. Components of the cell cytoskeleton are therapeutic targets in cancer. ßIV-tubulin is one such component that has two isotypes-ßIVa and ßIVb. ßIVa and ßIVb isotypes only differ in two amino acids at their C-terminus. Studies have implicated ßIVa-tubulin or ßIVb-tubulin expression with chemoresistance in prostate, breast, ovarian and lung cancer. However, no studies have examined the role of ßIV-tubulin in PC or attempted to identify isotype specific roles in regulating cancer cell growth and chemosensitivity. We aimed to determine the role of ßIVa- or ßIVb-tubulin on PC growth and chemosensitivity. PC cells (MiaPaCa-2, HPAF-II, AsPC1) were treated with siRNA (control, ßIVa-tubulin or ßIVb-tubulin). The ability of PC cells to form colonies in the presence or absence of chemotherapy was measured by clonogenic assays. Inhibition of ßIVa-tubulin in PC cells had no effect chemosensitivity. In contrast, inhibition of ßIVb-tubulin in PC cells sensitized to vinca alkaloids (Vincristine, Vinorelbine and Vinblastine), which was accompanied by increased apoptosis and enhanced cell cycle arrest. We show for the first time that ßIVb-tubulin, but not ßIVa-tubulin, plays a role in regulating vinca alkaloid chemosensitivity in PC cells. The results from this study suggest ßIVb-tubulin may be a novel therapeutic target and predictor of vinca alkaloid sensitivity for PC and warrants further investigation.

Fruit-derived phenolic compounds and pancreatic cancer: perspectives from Australian native fruits.

ETHNOPHARMACOLOGICAL RELEVANCE: Pancreatic cancer is a devastating cancer that presents late, is rapidly progressive and has current therapeutics with only limited efficacy. Bioactive compounds are ubiquitously present in fruits and numerous studies in vitro are addressing the activity of these compounds against pancreatic cancer, thus studies of specific bioactive compounds could lead to new anti-pancreatic cancer strategies. Australian native fruits have been used as foods and medicines by Australian Aboriginals for thousands of years, and preliminary studies have found these fruits to contain rich and diversified bioactive components with high antioxidant activity. Thus, Australian native fruits may possess key components for preventing or delaying the onset of tumorigenesis, or for the treatment of existing cancers, including pancreatic cancer. MATERIALS AND METHODS: Numerous databases including PubMed, SciFinder, Web of Knowledge, Scopus, and Sciencedirect were analysed for correlations between bioactive components from fruits and pancreatic cancer, as well as studies concerning Australian native fruits. RESULTS: In this review, we comprehensively highlight the proposed mechanisms of action of fruit bioactives as anti-cancer agents, update the potential anti-pancreatic cancer activity of various major classes of bioactive compounds derived from fruits, and discuss the existence of bioactive compounds identified from a selection Australian native fruits for future studies. CONCLUSION: Bioactive compounds derived from fruits possess the potential for the discovery of new anti-pancreatic cancer strategies. Further, Australian native fruits are rich in polyphenols including some flora that contain unique phenolic compounds, thereby warranting further investigations into their anti-cancer properties.

RNAi-mediated stathmin suppression reduces lung metastasis in an orthotopic neuroblastoma mouse model.

Metastatic neuroblastoma is an aggressive childhood cancer of neural crest origin. Stathmin, a microtubule destabilizing protein, is highly expressed in neuroblastoma although its functional role in this malignancy has not been addressed. Herein, we investigate stathmin's contribution to neuroblastoma tumor growth and metastasis. Small interfering RNA (siRNA)-mediated stathmin suppression in two independent neuroblastoma cell lines, BE(2)-C and SH-SY5Y, did not markedly influence cell proliferation, viability or anchorage-independent growth. In contrast, stathmin suppression significantly reduced cell migration and invasion in both the neuroblastoma cell lines. Stathmin suppression altered neuroblastoma cell morphology and this was associated with changes in the cytoskeleton, including increased tubulin polymer levels. Stathmin suppression also modulated phosphorylation of the actin-regulatory proteins, cofilin and myosin light chain (MLC). Treatment of stathmin-suppressed neuroblastoma cells with the ROCKI and ROCKII inhibitor, Y-27632, ablated MLC phosphorylation and returned the level of cofilin phosphorylation and cell invasion back to that of untreated control cells. ROCKII inhibition (H-1152) and siRNA suppression also reduced cofilin phosphorylation in stathmin-suppressed cells, indicating that ROCKII mediates stathmin's regulation of cofilin phosphorylation. This data demonstrates a link between stathmin and the regulation of cofilin and MLC phosphorylation via ROCK. To examine stathmin's role in neuroblastoma metastasis, stathmin short hairpin RNA (shRNA)\luciferase-expressing neuroblastoma cells were injected orthotopically into severe combined immunodeficiency-Beige mice, and tumor growth monitored by bioluminescent imaging. Stathmin suppression did not influence neuroblastoma cell engraftment or tumor growth. In contrast, stathmin suppression significantly reduced neuroblastoma lung metastases by 71% (P<0.008) compared with control. This is the first study to confirm a role for stathmin in hematogenous spread using a clinically relevant orthotopic cancer model, and has identified stathmin as an important contributor of cell invasion and metastasis in neuroblastoma.

Making decisions about delirium: a qualitative comparison of decision making between nurses working in palliative care, aged care, aged care psychiatry, and oncology.

BACKGROUND: Delirium has a significant impact on nursing practice from diagnosis and management, with under-detection and variable management of delirium being international problems. This study aimed to explore nurses' assessment and management of delirium when caring for people with cancer, the elderly or older people requiring psychiatric care in the inpatient setting. METHODS: Participants in this qualitative study were nurses working in Australian public hospital inpatient dedicated units in palliative care, aged care (geriatrics), aged care (geriatric) psychiatry and oncology. Semi-structured interviews were used to explore nurses' views about specific areas of delirium assessment and management. Purposive sampling was used and interviews conducted until thematic saturation reached. A thematic content analysis was performed from a grounded theory perspective. RESULTS: A total of 40 participants were included in the study. The analysis revealed four broad analytical themes: (1) superficial recognition and understanding of the operational definition of delirium or recognition of delirium as a syndrome; (2) nursing assessment: investigative versus a problem solving approach; (3) management: maintaining dignity and minimizing chaos; and (4) distress and the effect on others. DISCUSSION: Nurses have limited knowledge of the features of delirium regardless of their specialty discipline. Delirium was uniformly identified as a highly distressing experience for patients, families and staff alike. The majority of nurses had a superficial understanding of delirium management, and adopted a task-orientated approach aimed at addressing the more noticeable problems. These findings have implications for both education and knowledge translation. Innovative approaches are needed to align health professional behaviours with best evidence delirium care.

Myricetin induces pancreatic cancer cell death via the induction of apoptosis and inhibition of the phosphatidylinositol 3-kinase (PI3K) signaling pathway.

Pancreatic cancer is the fourth leading cause of cancer related deaths and is a disease with poor prognosis. It is refractory to standard chemotherapeutic drugs or to novel treatment modalities, making it imperative to find new treatments. In this study, using both primary and metastatic pancreatic cancer cell lines, we have demonstrated that the flavonoid myricetin induced pancreatic cancer cell death in vitro via apoptosis, and caused a decrease in PI3 kinase activity. In vivo, treatment of orthotopic pancreatic tumors with myricetin resulted in tumor regression and decreased metastatic spread. Importantly, myricetin was non-toxic, both in vitro and in vivo, underscoring its use as a therapeutic agent against pancreatic cancer.

Cortical activation and lamina terminalis functional connectivity during thirst and drinking in humans.

The pattern of regional brain activation in humans during thirst associated with dehydration, increased blood osmolality, and decreased blood volume is not known. Furthermore, there is little information available about associations between activation in osmoreceptive brain regions such as the organum vasculosum of the lamina terminalis and the brain regions implicated in thirst and its satiation in humans. With the objective of investigating the neuroanatomical correlates of dehydration and activation in the ventral lamina terminalis, this study involved exercise-induced sweating in 15 people and measures of regional cerebral blood flow (rCBF) using a functional magnetic resonance imaging technique called pulsed arterial spin labeling. Regional brain activations during dehydration, thirst, and postdrinking were consistent with the network previously identified during systemic hypertonic infusions, thus providing further evidence that the network is involved in monitoring body fluid and the experience of thirst. rCBF measurements in the ventral lamina terminalis were correlated with whole brain rCBF measures to identify regions that correlated with the osmoreceptive region. Regions implicated in the experience of thirst were identified including cingulate cortex, prefrontal cortex, striatum, parahippocampus, and cerebellum. Furthermore, the correlation of rCBF between the ventral lamina terminalis and the cingulate cortex and insula was different for the states of thirst and recent drinking, suggesting that functional connectivity of the ventral lamina terminalis is a dynamic process influenced by hydration status and ingestive behavior.

Health, economic, psychological and social impact of educating carers of patients with advanced pulmonary disease (protocol).

People with advanced pulmonary disease (APD), such as those with chronic obstructive pulmonary disease, have markedly impaired quality of life. Home Oxygen Therapy (HOT) itself is burdensome, although it often improves survival duration and quality of life in these patients. The exact burdens on informal caregivers of these patients are unknown. The central purpose of the pragmatic randomized controlled study described in this protocol is to determine the effectiveness of improving the skills and knowledge of carers of patients with APD who use HOT. Specifically we aimed to estimate the incremental impact of this carer intervention above usual care on health, economic, psychological and social domains for patient and carer dyads relative to the level of current burden. Eligible patients and their carers were recruited through three major hospitals, and randomized to an intervention or control group. The carers in the intervention group received two home-delivered education sessions based on the principles of academic detailing. Participants are currently being followed over 12 months. The primary outcome will be the proportion of patients surviving without a chronic obstructive pulmonary disease-related readmission / residential (non respite) care over 12 months. Carer secondary outcomes include perceived caregiver burden, level of expected and received social support, perceived level of mastery, self esteem, health related quality of life and disability, and ability to conduct domestic chores and household maintenance, social activities and provide service to others, and fatigue. Secondary patient outcomes include health related quality of life and disability, and current respiratory health status.

Unperceived treatment gaps in acute coronary syndromes.

BACKGROUND: Despite a strong evidence-base for several therapies recommended in the management of acute coronary syndromes (ACS), many patients do not receive these therapies. The barriers preventing translation of evidence into practice are incompletely understood. The aim of this study was to survey clinicians regarding barriers to implementing recommendations of recently published national clinical guidelines and to determine the extent to which these impact clinical practice. METHODS: A survey of clinicians at hospitals included in Australian Collaborative Acute Coronary Syndromes Prospective Audit (ACACIA, n = 3402, PML0051) was conducted, measuring self-stated knowledge, beliefs and guideline-concordant behaviours in relation to their care of ACS patients. Correlations between individual respondents' self-estimated rates and clinician's institutional rates of guideline-concordant behaviours were performed. RESULTS: Most respondents (n = 50/86, 58%) were aware of current guidelines and their scope, achieving 7/10 (Interquartile Range (IQR) = 2) median score on knowledge questions. Belief in benefits and agreement with guideline-recommended therapy was high. However, none of these factors correlated with increased use of guideline therapies. Apart from clopidogrel (r(s) = 0.28, p < 0.01) and early interventional therapy for high-risk non-ST elevation myocardial infarction (r(s) = 0.31, p < 0.01), there were no significant correlations between individual clinicians' self-estimated rates of guideline-concordant practice and rates recorded in ACACIA data for their respective institution. CONCLUSION: Beliefs about practice do not match actual practice. False beliefs regarding levels of evidence-based practice may contribute to inadequate implementation of evidence-based guidelines. Strategies such as continuous real-time audit and feedback of information for the delivery of care may help clinicians understand their levels of practice better and improve care.

Effect of aging on regional cerebral blood flow responses associated with osmotic thirst and its satiation by water drinking: a PET study.

Levels of thirst and ad libitum drinking decrease with advancing age, making older people vulnerable to dehydration. This study investigated age-related changes in brain responses to thirst and drinking in healthy men. Thirst was induced with hypertonic infusions (3.1 ml/kg 0.51M NaCl) in young (Y) and older (O) subjects. Regional cerebral blood flow (rCBF) was measured with positron emission tomography (PET). Thirst activations were identified by correlating rCBF with thirst ratings. Average rCBF was measured from regions of interest (ROI) corresponding to activation clusters in each group. The effects of drinking were examined by correlating volume of water drunk with changes in ROI rCBF from maximum thirst to postdrinking. There were increases in blood osmolality (Y, 2.8 +/- 1.8%; O, 2.2 +/- 1.4%) and thirst ratings (Y, 3.1 +/- 2.1; O, 3.7 +/- 2.8) from baseline to the end of the hypertonic infusion. Older subjects drank less water (1.9 +/- 1.6 ml/kg) than younger subjects (3.9 +/- 1.9 ml/kg). Thirst-related activation was evident in S1/M1, prefrontal cortex, anterior midcingulate cortex (aMCC), premotor cortex, and superior temporal gyrus in both groups. Postdrinking changes of rCBF in the aMCC correlated with drinking volumes in both groups. There was a greater reduction in aMCC rCBF relative to water drunk in the older group. Aging is associated with changes in satiation that militate against adequate hydration in response to hyperosmolarity, although it is unclear whether these alterations are due to changes in primary afferent inflow or higher cortical functioning.

Improving the management of acute coronary syndromes in Australia: translating evidence to outcomes.

Cardiovascular disease imposes a heavy burden of morbidity and mortality on the Australian community. This situation is likely to exacerbate as the number of elderly Australians increase. Management of acute coronary syndromes (ACS) is underpinned by a robust evidence base, which is outlined in clinical practice guidelines. Yet, despite wide diffusion of guidelines, many Australians who experience acute coronary syndromes do not receive optimal care. This article reviews what we have learnt from previous quality improvement initiatives and discusses what we need to know to improve acute coronary syndromes management in Australia.

Transmission of Xylella fastidiosa, Causal Agent of Citrus Variegated Chlorosis, by the Glassy-Winged Sharpshooter, Homalodisca coagulata.

Citrus variegated chlorosis (CVC) is an economically important disease of citrus in Brazil and Argentina. The causal pathogen is a strain of Xylella fastidiosa transmitted by several sharpshooter species. The glassy-winged sharpshooter (GWSS), Homalodisca coagulata, has become an important new pest of citrus and grapevines in California, where it transmits X. fastidiosa strains to several crops including grapes, oleander, and almonds. Transmission studies over a 3-year period at the USDA BSL3-P containment facility at Fort Detrick, MD, utilizing California field-collected GWSS, a Brazilian strain of CVC, and Madam Vinous sweet orange seedlings, have shown a consistent although low level of transmission of CVC. Test plants were observed for CVC symptoms, analyzed by polymerase chain reaction using species-specific primers for X. fastidiosa, membrane entrapment immunofluorescence, and scanning electron microscopy. X. fastidiosa was not detected in field-collected GWSS but was detected in GWSS following feeding on CVC-infected source plants. Transmission of the CVC strain of X. fastidiosa by GWSS increases the risk of establishment of CVC in the United States if it were introduced.

Vitamin A inhibits pancreatic stellate cell activation: implications for treatment of pancreatic fibrosis.

BACKGROUND AND AIMS: Activated pancreatic stellate cells (PSCs) are implicated in the production of alcohol induced pancreatic fibrosis. PSC activation is invariably associated with loss of cytoplasmic vitamin A (retinol) stores. Furthermore, retinol and ethanol are known to be metabolised by similar pathways. Our group and others have demonstrated that ethanol induced PSC activation is mediated by the mitogen activated protein kinase (MAPK) pathway but the specific role of retinol and its metabolites all-trans retinoic acid (ATRA) and 9-cis retinoic acid (9-RA) in PSC quiescence/activation, or its influence on ethanol induced PSC activation is not known. Therefore, the aims of this study were to (i) examine the effects of retinol, ATRA, and 9-RA on PSC activation; (ii) determine whether retinol, ATRA, and 9-RA influence MAPK signalling in PSCs; and (iii) assess the effect of retinol supplementation on PSCs activated by ethanol. METHODS: Cultured rat PSCs were incubated with retinol, ATRA, or 9-RA for varying time periods and assessed for: (i) proliferation; (ii) expression of alpha smooth muscle actin (alpha-SMA), collagen I, fibronectin, and laminin; and (iii) activation of MAPKs (extracellular regulated kinases 1 and 2, p38 kinase, and c-Jun N terminal kinase). The effect of retinol on PSCs treated with ethanol was also examined by incubating cells with ethanol in the presence or absence of retinol for five days, followed by assessment of alpha-SMA, collagen I, fibronectin, and laminin expression. RESULTS: Retinol, ATRA, and 9-RA significantly inhibited: (i) cell proliferation, (ii) expression of alpha-SMA, collagen I, fibronectin, and laminin, and (iii) activation of all three classes of MAPKs. Furthermore, retinol prevented ethanol induced PSC activation, as indicated by inhibition of the ethanol induced increase in alpha-SMA, collagen I, fibronectin, and laminin expression. CONCLUSIONS: Retinol and its metabolites ATRA and 9-RA induce quiescence in culture activated PSCs associated with a significant decrease in the activation of all three classes of MAPKs in PSCs. Ethanol induced PSC activation is prevented by retinol supplementation.

Desmoplastic reaction in pancreatic cancer: role of pancreatic stellate cells.

OBJECTIVES: Pancreatic cancer has a very poor prognosis, largely due to its propensity for early local and distant spread. Histopathologically, most pancreatic cancers are characterized by a prominent stromal/fibrous reaction in and around tumor tissue. The aims of this study were to determine whether (1) the cells responsible for the formation of the stromal reaction in human pancreatic cancers are activated pancreatic stellate cells (PSCs) and (2) an interaction exists between pancreatic cancer cells and PSCs that may facilitate local and distant invasion of tumor. METHODS: Serial sections of human pancreatic cancer tissue were stained for desmin and glial fibrillary acidic protein (stellate cell selective markers) and alpha-smooth muscle actin (alphaSMA), a marker of activated PSC activation, by immunohistochemistry, and for collagen using Sirius Red. Correlation between the extent of positive staining for collagen and alphaSMA was assessed by morphometry. The cellular source of collagen in stromal areas was identified using dual staining methodology, ie, immunostaining for alphaSMA and in situ hybridization for procollagen alpha1I mRNA. The possible interaction between pancreatic cancer cells and PSCs was assessed in vitro by exposing cultured rat PSCs to control medium or conditioned medium from 2 pancreatic cancer cell lines (PANC-1 and MiaPaCa-2) for 24 hours. PSC activation was assessed by cell proliferation and alphaSMA expression. RESULTS: Stromal areas of human pancreatic cancer stained strongly positive for the stellate cell selective markers desmin and GFAP (indicating the presence of PSCs), for alphaSMA (suggesting that the PSCs were in their activated state) and for collagen. Morphometric analysis demonstrated a close correlation (r = 0.77; P < 0.04; 8 paired sections) between the extent of PSC activation and collagen deposition. Procollagen mRNA expression was localized to alphaSMA-positive cells in stromal areas indicating that activated PSCs were the predominant source of collagen in stromal areas. Exposure of PSCs to pancreatic cancer cell secretions in vitro resulted in PSC activation as indicated by significantly increased cell proliferation and alphaSMA expression. CONCLUSIONS: Activated PSCs are present in the stromal reaction in pancreatic cancers and are responsible for the production of stromal collagen. PSC function is influenced by pancreatic cancer cells. Interactions between tumor cells and stromal cells (PSCs) may play an important role in the pathobiology of pancreatic cancer.

Increased thirst and vasopressin secretion after myocardial infarction in rats.

Impaired regulation of salt and water balance in left ventricular dysfunction and heart failure can lead to pulmonary and peripheral edema and hyponatremia. Previous studies of disordered water regulation in heart failure have used models of low cardiac output with normal cardiac function (e.g., inferior vena cava ligation). We investigated thirst and vasopressin (AVP) secretion in a rat myocardial infarction model of chronic left ventricular dysfunction/heart failure in response to a 24-h water deprivation period. Thirst (implied from water drunk), hematocrit, plasma renin activity, and plasma AVP concentrations increased with water deprivation vs. ad libitum water access. Thirst and plasma AVP concentrations were significantly positively correlated with infarct size after 24-h water deprivation but not under ad libitum water access conditions. The mechanism by which this occurs is unclear but could involve increased osmoreceptor sensitivity, altered stimulation of baroreceptors, the renin-angiotensin system, or altered central neural control.

Pancreatic stellate cell activation by ethanol and acetaldehyde: is it mediated by the mitogen-activated protein kinase signaling pathway?

BACKGROUND: Pancreatic fibrosis is a characteristic feature of alcoholic chronic pancreatitis. Recent studies suggest that activated pancreatic stellate cells (PSCs) are the major cell-type involved in pancreatic fibrogenesis. Cultured PSCs become activated when exposed to ethanol or its metabolite acetaldehyde (as indicated by increased alpha-smooth muscle actin [alpha-SMA] expression and increased collagen synthesis). However the intracellular signaling mechanisms responsible for ethanol- or acetaldehyde-induced PSC activation remain to be fully elucidated. One of the major signaling pathways known to regulate protein synthesis in mammalian cells is the mitogen-activated protein kinase (MARK) pathway. AIMS: To examine the effects of ethanol and acetaldehyde on the MAPK pathway (by assessing the activities of the 3 major subfamilies (extracellular-regulated kinases 1 and 2 [ERK 1/2], JNK and p38 kinase) in PSCs and to examine the role of p38 kinase in mediating the ethanol- and acetaldehyde-induced increase in alpha-SMA expression in activated rat PSCs. METHODS: Rat PSCs were incubated with ethanol (50 mM) or acetaldehyde (200 microM) for 15 min, 30 min, 60 min, and 24 h; and activities of ERK 1/2, JNK, and p38 kinase were assessed in cell lysates using kinase assays and Western blot. In addition, rat PSCs were treated with the specific p38 MAPK inhibitor SB203580 in the presence or absence of ethanol or acetaldehyde for 24h, and activation of the downstream protein kinase MAPKAP kinase-2 (an indicator of p38 MAPK activity) was assessed by Western blot. Specific inhibitors were also used to inhibit the activity of ERK 1/2 and JNK. Following inhibition of the above signaling pathways, alpha-SMA expression by PSCs was assessed by Western blot. RESULTS: Ethanol and acetaldehyde increased the activation of all 3 subfamilies (ERK 1/2, JNK and p38 kinase) of the MAPK pathway in PSCs. Treatment of PSCs with SB203580 abolished the ethanol- and acetaldehyde-induced increase in p38 MAPK activity and also prevented the induction of alpha-SMA expression in PSCs. However, inhibition of ERK 1/2 and JNK had no effect on ethanoland acetaldehyde-induced alpha-SMA expression in PSCs. CONCLUSIONS: (1) The MAP kinase pathway is induced in PSCs after exposure to ethanol or acetaldehyde and this induction is sustained for at least 24h. (2) The p38 MAPK pathway mediates the activation (as indicated by increased alpha-SMA expression) of PSCs by ethanol or acetaldehyde.

Cell migration: a novel aspect of pancreatic stellate cell biology.

BACKGROUND: Pancreatic stellate cells (PSCs), implicated as key mediators of pancreatic fibrogenesis, are found in increased numbers in areas of pancreatic injury. This increase in PSC number may be due to increased local proliferation and/or migration of these cells from adjacent areas. The ability of PSCs to proliferate has been well established but their potential for migration has not been examined. AIMS: Therefore, the aims of this study were to determine whether cultured rat PSCs have the capacity to migrate and, if so, to characterise this migratory capacity with respect to the influence of basement membrane components and the effect of platelet derived growth factor (PDGF, a known stimulant for migration of other cell types). METHODS: Migration of freshly isolated (quiescent) and culture activated (passaged) rat PSCs was assessed across uncoated or Matrigel (a basement membrane-like substance) coated porous membranes (pore size 8 micro m) in the presence or absence of PDGF (10 and 20 ng/ml) in the culture medium. A checkerboard assay was performed to assess whether the effect of PDGF on PSC migration was chemotactic or chemokinetic. RESULTS: Cell migration was observed with both freshly isolated and passaged PSCs. However, compared with passaged (culture activated) cells, migration of freshly isolated cells was delayed, occurring only at or after 48 hours of incubation when the cells displayed an activated phenotype. PSC migration through Matrigel coated membranes was delayed but not prevented by basement membrane components. PSC migration was increased by PDGF and this effect was predominantly chemotactic (that is, in the direction of a positive concentration gradient). CONCLUSIONS: (i) PSCs have the capacity to migrate. (ii) Activation of PSCs appears to be a prerequisite for migration. (iii) PDGF stimulates PSC migration and this effect is predominantly chemotactic. IMPLICATION: Chemotactic factors released during pancreatic injury may stimulate the migration of PSCs through surrounding basement membrane towards affected areas of the gland.

Endothelin ETA receptor antagonism does not attenuate angiotensin II-induced cardiac hypertrophy in vivo in rats.

1. Angiotensin (Ang) II causes cardiac hypertrophy in vitro and in vivo. It also stimulates the release of endothelin (ET)-1. Endothelin-1 induces hypertrophy of cardiomyocytes in vitro. 2. In the present study, we examined whether the cardiac hypertrophic action of AngII in vivo was mediated by ET-1 via ETA receptors. We also determined whether arginine vasopressin (AVP), another ET-1 stimulator, could cause cardiac hypertrophy in vivo through an ET-1-dependent pathway. 3. In Sprague-Dawley rats (n = 8 per group), we determined whether the orally administered ETA receptor antagonist BMS 193884 could attenuate the cardiac hypertrophic effect of: (i) i.v. AngII infusion at either 100 or 200 ng/kg per min, i.v., for 1 week; (ii) AngII infusion at 100 ng/kg per min, i.v., for 2 weeks; and (iii) AVP infusion at either 2 or 10 ng/kg per min, i.v., for 1 week. Mean arterial pressure and heart rate were also measured. 4. Infusion with AngII for both 1 and 2 weeks increased left ventricular weight. Only AngII infusion at 200 ng/kg per min for 1 week increased blood pressure. Endothelin ETA receptor blockade did not attenuate the left ventricular hypertrophy, even though it reduced the hypertensive effect of AngII. Arginine vasopressin increased blood pressure, but did not cause cardiac hypertrophy. 5. We showed that AngII can cause cardiac hypertrophy through a direct, blood pressure-independent effect on the heart. Endothelin-1 did not mediate the cardiac hypertrophic effect of AngII through ETA receptors. This may indicate the involvement of ETB receptors in this model of cardiac hypertrophy. Arginine vasopressin did not cause cardiac hypertrophy in vivo.

Rat pancreatic stellate cells secrete matrix metalloproteinases: implications for extracellular matrix turnover.

BACKGROUND: Pancreatic fibrosis is a characteristic feature of chronic pancreatic injury and is thought to result from a change in the balance between synthesis and degradation of extracellular matrix (ECM) proteins. Recent studies suggest that activated pancreatic stellate cells (PSCs) play a central role in pancreatic fibrogenesis via increased synthesis of ECM proteins. However, the role of these cells in ECM protein degradation has not been fully elucidated. AIMS: To determine: (i) whether PSCs secrete matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) and, if so (ii) whether MMP and TIMP secretion by PSCs is altered in response to known PSC activating factors such as tumour necrosis factor alpha (TNF-alpha), transforming growth factor beta1 (TGF-beta1), interleukin 6 (IL-6), ethanol, and acetaldehyde. METHODS: Cultured rat PSCs (n=3-5 separate cell preparations) were incubated at 37 degrees C for 24 hours with serum free culture medium containing TNF-alpha (5-25 U/ml), TGF-beta1 (0.5-1 ng/ml), IL-6 (0.001-10 ng/ml), ethanol (10-50 mM), or acetaldehyde (150-200 micro M), or no additions (controls). Medium from control cells was examined for the presence of MMPs by zymography using a 10% polyacrylamide-0.1% gelatin gel. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to examine gene expression of MMP9 and the tissue inhibitors of metalloproteinases TIMP1 and TIMP2. Western blotting was used to identify a specific MMP, MMP2 (a gelatinase that digests basement membrane collagen and the dominant MMP observed on zymography) and a specific TIMP, TIMP2. Reverse zymography was used to examine functional TIMPs in PSC secretions. The effect of TNF-alpha, TGF-beta1, and IL-6 on MMP2 secretion was assessed by densitometry of western blots. The effect of ethanol and acetaldehyde on MMP2 and TIMP2 secretion was also assessed by this method. RESULTS: Zymography revealed that PSCs secrete a number of MMPs including proteinases with molecular weights consistent with MMP2, MMP9, and MMP13. RT-PCR demonstrated the presence of mRNA for metalloproteinase inhibitors TIMP1 and TIMP2 in PSCs while reverse zymography revealed the presence of functional TIMP2 in PSC secretions. MMP2 secretion by PSCs was significantly increased by TGF-beta1 and IL-6, but was not affected by TNF-alpha. Ethanol and acetaldehyde induced secretion of both MMP2 and TIMP2 by PSCs. CONCLUSIONS: Pancreatic stellate cells have the capacity to synthesise a number of matrix metalloproteinases, including MMP2, MMP9, and MMP13 and their inhibitors TIMP1 and TIMP2. MMP2 secretion by PSCs is significantly increased on exposure to the proinflammatory cytokines TGF-beta1 and IL-6. Both ethanol and its metabolite acetaldehyde increase MMP2 as well as TIMP2 secretion by PSCs. IMPLICATION: The role of pancreatic stellate cells in extracellular matrix formation and fibrogenesis may be related to their capacity to regulate the degradation as well as the synthesis of extracellular matrix proteins.