[Preparation of metagenomic DNA from bronchoalveolar lavage fluids of patients with chronic obstructive pulmonary diseases].

OBJECTIVE: To optimize the method of isolating a small amount of metagenomic DNA efficiently from bronchoalveolar lavage fluids (BALF) of patients with stable chronic obstructive pulmonary diseases (COPD) , which will facilitate subsequent PCR and DNA sequencing. METHODS: BALF (5mL) of stable COPD patients was spun down to collect the cells. To extract genomic DNA from Gram-positive bacteria more efficiently, QIAGEN's DNA extraction protocol was optimized as follows: Added Buffer ATL to the pellets and used bead tubes and tissue homogenizers to break cell walls; then added proteinase K and incubated; after adding Buffer AL and ethanol, pipetted the mixture into a DNeasy spin column then centrifuged; washed the column with Buffer AW1 and Buffer AW2, finally added 50 microL Buffer AE to elute DNA. After measuring the total DNA concentration, the bacterial 16S rDNA was amplified by PCR and amplicon libraries were created for further determination. RESULTS: The DNA content of BALF with optimized protocols was 467.5 (135.0-1697.5) ng, which was significantly higher than those extracted with phenol-chloroform 95.0 (0-612.5) ng. After optimizing, more 16S rDNA PCR production can be obtained for future analysis (P = 0.002). CONCLUSION: The optimized DNA extraction methods combining DNA isolation kits with bead-beating were more efficient in isolating tiny metagenomic DNA from BALF.

Regulation of alveolar epithelial cell apoptosis and pulmonary fibrosis by coordinate expression of components of the fibrinolytic system.

Alveolar type II (ATII) cell apoptosis and depressed fibrinolysis that promotes alveolar fibrin deposition are associated with acute lung injury (ALI) and the development of pulmonary fibrosis (PF). We therefore sought to determine whether p53-mediated inhibition of urokinase-type plasminogen activator (uPA) and induction of plasminogen activator inhibitor-1 (PAI-1) contribute to ATII cell apoptosis that precedes the development of PF. We also sought to determine whether caveolin-1 scaffolding domain peptide (CSP) reverses these changes to protect against ALI and PF. Tissues as well as isolated ATII cells from the lungs of wild-type (WT) mice with BLM injury show increased apoptosis, p53, and PAI-1, and reciprocal suppression of uPA and uPA receptor (uPAR) protein expression. Treatment of WT mice with CSP reverses these effects and protects ATII cells against bleomycin (BLM)-induced apoptosis whereas CSP fails to attenuate ATII cell apoptosis or decrease p53 or PAI-1 in uPA-deficient mice. These mice demonstrate more severe PF. Thus p53 is increased and inhibits expression of uPA and uPAR while increasing PAI-1, changes that promote ATII cell apoptosis in mice with BLM-induced ALI. We show that CSP, an intervention targeting this pathway, protects the lung epithelium from apoptosis and prevents PF in BLM-induced lung injury via uPA-mediated inhibition of p53 and PAI-1.

Hepatocyte growth factor acts as a mitogen and chemoattractant for postnatal subventricular zone-olfactory bulb neurogenesis.

Neural progenitor cells persist throughout life in the forebrain subventricular zone (SVZ). They generate neuroblasts that migrate to the olfactory bulb and differentiate into interneurons, but mechanisms underlying these processes are poorly understood. Hepatocyte growth factor/scatter factor (HGF/SF) is a pleiotropic factor that influences cell motility, proliferation and morphogenesis in neural and non-neural tissues. HGF and its receptor, c-Met, are present in the rodent SVZ-olfactory bulb pathway. Using in vitro neurogenesis assays and in vivo studies of partially HGF-deficient mice, we find that HGF promotes SVZ cell proliferation and progenitor cell maintenance, while slowing differentiation and possibly altering cell fate choices. HGF also acts as a chemoattractant for SVZ neuroblasts in co-culture assays. Decreased HGF signaling induces ectopic SVZ neuroblast migration and alters the timing of migration to the olfactory bulb. These results suggest that HGF influences multiple steps in postnatal forebrain neurogenesis. HGF is a mitogen for SVZ neural progenitors, and regulates their differentiation and olfactory bulb migration.

Induction of tissue factor by urokinase in lung epithelial cells and in the lungs.

RATIONALE: Urokinase-type plasminogen activator (uPA) regulates extracellular proteolysis in lung injury and repair. Although alveolar expression of uPA increases, procoagulant activity predominates. OBJECTIVES: This study was designed to investigate whether uPA alters the expression of tissue factor (TF), the major initiator of the coagulation cascade, in lung epithelial cells (ECs). METHODS: Bronchial, primary airway ECs and C57B6 wild-type, uPA-deficient (uPA(-/-)) mice were exposed to phosphate-buffered saline, uPA, or LPS. Immunohistochemistry, protein, cellular, and molecular techniques were used to assess TF expression and activity. MEASUREMENTS AND MAIN RESULTS: uPA enhanced TF mRNA and protein expression, and TF-dependent coagulation in lung ECs. uPA-induced expression of TF involves both increased synthesis and enhanced stabilization of TF mRNA. uPA catalytic activity had little effect on induction of TF. By contrast, deletion of the uPA receptor binding growth factor domain from uPA markedly attenuated the induction of TF, suggesting that uPA receptor binding is sufficient for TF induction. Lung tissues of uPA-deficient mice expressed less TF protein and mRNA compared with wild-type mice. In addition, intratracheal instillation of mouse uPA increased TF mRNA and protein expression and accelerated coagulation in lung tissues. uPA(-/-) mice exposed to LPS failed to induce TF. CONCLUSIONS: uPA increased TF expression and TF-dependent coagulation in the lungs of mice. We hypothesize that uPA-mediated induction of TF occurs in lung ECs to promote increased fibrin deposition in the airways during acute lung injury.

Predictors of job satisfaction among academic faculty members: do instructional and clinical staff differ?

OBJECTIVES: This study aimed to identify and compare predictors of job satisfaction between instructional and clinical faculty members. METHODS: A 61-item faculty job satisfaction survey was distributed to 1898 academic faculty members at the University of Michigan Medical School. The anonymous survey was web-based. Questions covered topics on departmental organisation, research, clinical and teaching support, compensation, mentorship, and promotion. Levels of satisfaction were contrasted between faculty members on the two tracks, and predictors of job satisfaction were identified using linear regression models. RESULTS: Response rates for the instructional and clinical faculty groups were 43.1% and 46.7%, respectively. Clinical faculty members reported being less satisfied with how they were mentored and fewer reported understanding the process for promotion. There was no significant difference in overall job satisfaction between the two faculty groups. Surprisingly, clinical faculty members with mentors were significantly less satisfied with how they were mentored and with career advancement, and were significantly less likely to choose an academic career if they had to do it all over again compared with instructional faculty mentees. Additionally, senior-level clinical faculty members were significantly less satisfied with their opportunities to mentor junior faculty members compared with senior-level instructional faculty staff. Significant predictors of job satisfaction for both groups included areas of autonomy, meeting career expectations, work-life balance, and departmental leadership. In the clinical track only, compensation and career advancement variables also emerged as significant predictors of overall job satisfaction. CONCLUSIONS: Greater emphasis must be placed on faculty members' well-being at both the institutional level and the level of departmental leadership. Efforts to enhance job satisfaction and improve retention are more likely to succeed if they are directed by locally designed assessments involving department chairs and are specifically aimed at fostering more effective mentoring relationships and increasing the opportunities available for career advancement activities such as research work. Our findings show that these strategies can have significant impacts on job satisfaction and the retention of clinical track faculty members.

Symptom-related sputum microbiota in stable chronic obstructive pulmonary disease.

Background: The role of airway microbiota in COPD is highly debated. Symptomology assessment is vital for the management of clinically stable COPD patients; however, the link between symp toms and the airway microbiome is currently unknown. Purpose: The present study aimed to evaluate the relationship among stable COPD patients. Patients and methods: We conducted pyrosequencing of bacterial 16S rRNA using induced sputum samples in a Han Chinese cohort that included 40 clinically stable COPD patients and 19 healthy controls. Results: Alterations in community composition and core bacte rial taxa (Neisseria subflava, etc.) were observed in patients with severe symptoms compared with controls. The co-occurrence network indicated that the key microbiota enriched in COPD patients showed higher expression in patients with severe symptoms. The association pattern of symptoms with the sputum microbiome was obviously different from that of lung function in COPD patients. Conclusion: These findings broaden our insights into the relationship between the sputum microbiota and the symptom severity in COPD patients, emphasizing the role of symptoms in the airway microbiome, independent of lung function.

Current and emerging drugs for idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis is a chronic, progressive and often fatal form of interstitial lung disease. It is characterized by injury with loss of lung epithelial cells and abnormal tissue repair, resulting in abnormal accumulation of fibroblasts and myofibroblasts, deposition of extracellular matrix and distortion of lung architecture, leading to respiratory failure. This lethal lung disorder continues to pose major clinical challenges as an effective therapeutic regimen has yet to be developed. In this report, therapeutic strategies are reviewed, including the use of antifibrotic agents, inhibition of cytokines, leukotrienes and cytokines receptors, and molecular targeting of specific signaling pathways during fibrotic processes and angiogenesis. This article examines the body of evidence supporting present therapies and reviews the newer agents being tested in patients with idiopathic pulmonary fibrosis.

Urokinase is required for the formation of mactinin, an alpha-actinin fragment that promotes monocyte/macrophage maturation.

We have previously shown that lysates from HL-60 myeloid leukemia cells or from peripheral blood monocytes are able to degrade alpha-actinin to form a 31-kDa amino-terminal fragment with monocyte/macrophage maturation promoting activity. In contrast, intact alpha-actinin, which is a 100-kDa actin-binding protein, has no differentiating activity. The aim of this study was to investigate the enzyme responsible for the degradation of alpha-actinin to form this fragment, named mactinin. The ability of cell lysates to degrade [125I]alpha-actinin in the presence of various enzyme inhibitors, including inhibitors of metalloproteinases, cysteine proteinases, and serine proteases, was measured. Phenylmethylsulfonyl fluoride (PMSF) was the only inhibitor able to prevent formation of mactinin by cell lysate degradation of alpha-actinin, suggesting that a serine protease is responsible for the digestion. Of the various serine proteases tested (thrombin, plasmin, and urokinase), only urokinase was able to produce a 31-kDa band. The urokinase-generated 31-kDa band promoted maturation in HL-60 cells. Amiloride, a specific inhibitor of urokinase, inhibited production of the 31-kDa alpha-actinin fragment by HL-60 cell lysates. For in vivo tests, inflammatory fluid (from bronchoalvelolar lavage) was collected from uPA (urokinase) knockout mice and their wild-type counterparts after intratracheal challenge with Pneumocystis carinii. Although most (6 of 8) wild-type mice had mactinin in their inflammatory fluid samples, none (0 of 8) of the uPA knockout mice had mactinin present (P<0.01). These results demonstrate that urokinase is necessary and sufficient for the formation of the monocyte/macrophage maturation promoting fragment, mactinin, in vitro and in vivo. These findings support the role of urokinase in the regulation of monocyte/macrophage functions, such as that occurring in inflammatory reactions.

Urokinase-deficient and urokinase receptor-deficient mice have impaired neutrophil antimicrobial activation in vitro.

Leukocytes express both urokinase-type plasminogen activator (uPA) and the urokinase receptor (uPAR, CD87). We have shown that neutrophil recruitment to the lung during P. aeruginosa pneumonia is impaired in uPAR-deficient (uPAR-/-) mice but is normal in uPA-/- mice. However, both uPA-/- mice and uPAR-/- mice have impaired lung clearance of P. aeruginosa compared with wild-type (WT) mice. To determine the role of uPA and uPAR in antibacterial host defense, we compared neutrophil bacterial-phagocytosis, respiratory burst, and degranulation among uPA-/-, uPAR-/-, and WT mice. Neutrophil phagocytosis was significantly diminished comparing uPA-/- and uPAR-/- mice with WT mice at all time points. The generation of superoxide by both uPA-/- and uPAR-/- neutrophils was about half of that seen in WT neutrophils. Degranulation of azurophilic granules was significantly diminished in uPA-/- neutrophils compared with either uPAR-/- or WT neutrophils. By contrast, agonist-stimulated release of specific granules was not diminished in either uPA-/- or uPAR-/- mice compared with WT. We conclude that the uPA/uPAR system modulates several of the crucial steps in neutrophil activation that result in bacterial killing and effective innate host defense.

Gender Disparities in Academic Practice.

BACKGROUND: In academia, women remain underrepresented. The authors' sought to examine differences in faculty position and professional satisfaction among academic physicians by gender. METHODS: From 2008 to 2012, academic faculty members at a single institution were surveyed (2008, n = 737; 2010, n = 1151; and 2012, n = 971) regarding current position, choice of position, professional satisfaction, and desire for leaving. Logistic regression was performed to compare aspects of professional satisfaction by gender. RESULTS: Men more often held tenure track positions compared with women (2008, 45 percent versus 20 percent; 2010, 47 percent versus 20 percent; and 2012, 49 percent versus 20 percent; p < 0.001). Women were more likely to engage in only clinical activities compared with men (2008, 31 percent versus 18 percent; 2010, 28 percent versus 14 percent; and 2012, 33 percent versus 13 percent; p < 0.001) and less likely to participate in research. Women chose tracks to accommodate work-life balance [2008, OR, 1.9 (95 percent CI, 1.29 to 2.76); 2010, OR, 2.0 (95 percent CI, 1.38 to 2.76); and 2012, OR, 2.1 (95 percent CI, 1.40 to 3.00)], rather than the opportunity of tenure [2008, OR, 0.4 (95 percent CI, 0.23 to 0.75); 2010, OR, 0.5 (95 percent CI, 0.35 to 0.85); and 2012, OR, 0.5 (95 percent CI, 0.29 to 0.76) compared with men. Men reported higher professional satisfaction compared with women (2008, 5.7 versus 5.4, p < 0.009; 2012, 5.3 versus 5.0, p < 0.03). Men were more likely to leave because of leadership opportunities (14.4 percent versus 9.2 percent, p < 0.03) and compensation (14.2 percent versus 9.2 percent, p < 0.03) compared with women. CONCLUSIONS: Women report lower levels of professional satisfaction in academic practice compared with men. Given the increasing pressures of academic practice, efforts to align work-life balance and professional goals could potentially improve faculty satisfaction and retention.

Use of direct gradient analysis to uncover biological hypotheses in 16s survey data and beyond.

This study investigated the use of direct gradient analysis of bacterial 16S pyrosequencing surveys to identify relevant bacterial community signals in the midst of a "noisy" background, and to facilitate hypothesis-testing both within and beyond the realm of ecological surveys. The results, utilizing 3 different real world data sets, demonstrate the utility of adding direct gradient analysis to any analysis that draws conclusions from indirect methods such as Principal Component Analysis (PCA) and Principal Coordinates Analysis (PCoA). Direct gradient analysis produces testable models, and can identify significant patterns in the midst of noisy data. Additionally, we demonstrate that direct gradient analysis can be used with other kinds of multivariate data sets, such as flow cytometric data, to identify differentially expressed populations. The results of this study demonstrate the utility of direct gradient analysis in microbial ecology and in other areas of research where large multivariate data sets are involved.

Activation of urokinase plasminogen activator and its receptor axis is essential for macrophage infiltration in a prostate cancer mouse model.

Macrophages within the tumor microenvironment promote angiogenesis, extracellular matrix breakdown, and tumor cell migration, invasion, and metastasis. Activation of the urokinase plasminogen activator (uPA) and its receptor (uPAR) axis promotes prostate cancer tumorigenicity, invasion, metastasis, and survival within the tumor microenvironment. The link between macrophage infiltration and the uPA/uPAR axis in prostate cancer development has not been established, although it has been reported that uPA plays a critical role inmonocyte and macrophage chemotaxis. In this study, murine prostate cancer RM-1 cells were subcutaneously inoculated into wild-type (WT), uPA(-/-), and uPAR(-/-) mice. Tumor volume was significantly diminished in both uPA(-/-) and uPAR(-/-) mice compared with WT controls. Greater inhibition of tumor volume was also observed in uPA(-/-) mice compared with uPAR(-/-) mice, suggesting the important contribution of stromal-derived uPA to sustain the tumor growth. Immunohistochemical staining revealed that tumors in uPA(-/-) and uPAR(-/-) mice displayed significantly lower proliferative indices, higher apoptotic indices, and less neovascularity compared with the tumors in WT mice. Tumors in uPA(-/-) and uPAR(-/-) mice displayed significantly less macrophage infiltration as demonstrated by F4/80 staining and MAC3(+) cell numbers by flow cytometry compared with the tumors from WT mice. These findings suggest that the uPA/uPAR axis acts in both autocrine and paracrine manners in the tumor microenvironment, and activation of uPA/uPAR axis is essential for macrophage infiltration into prostate tumors.

The role of urokinase in idiopathic pulmonary fibrosis and implication for therapy.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive and frequently fatal form of interstitial lung disease for which there are no proven drug therapies. The pathogenesis of IPF is complex and the urokinase-type plasminogen activator (uPA)/plasminogen system participates in the repair process. The balance between the activating enzyme uPA, and its inhibitor PAI-1, is a critical determinant of the amount of scar development that follows. OBJECTIVE: To address the role of urokinase in the pathogenesis of pulmonary fibrosis and its implications for therapy. METHODS: We reviewed a spectrum of therapeutic strategies and focused on fibrinolytic and anticoagulant drugs for IPF patients. RESULTS/CONCLUSION: There is currently a search for new pharmacotherapeutic agents that may modulate the fibrogenic pathways in IPF. Either blocking PAI-1 or using uPA itself may be a promising new therapeutic strategy.

New insights into the pathogenesis and treatment of idiopathic pulmonary fibrosis: a potential role for stem cells in the lung parenchyma and implications for therapy.

Idiopathic Pulmonary Fibrosis (IPF) is a chronic, progressive, and often fatal form of interstitial lung disease. It is characterized by injury with loss of lung epithelial cells and abnormal tissue repair, resulting in replacement of normal functional tissue, abnormal accumulation of fibroblasts and myofibroblasts, deposition of extracellular matrix, and distortion of lung architecture which results in respiratory failure. Despite improvements in the diagnostic approach to IPF and active research in recent years, the molecular mechanisms of the disease remain poorly understood. This highly lethal lung disorder continues to pose major clinical challenges since an effective therapeutic regimen has yet to be identified and developed. For example, a treatment modality has been based on the assumption that IPF is a chronic inflammatory disease, yet most available anti-inflammatory drugs are not effective in treating it. Hence researchers are now focusing on understanding alternative underlying mechanisms involved in the pathogenesis of IPF in the hope of discovering potentially new pharmaceutical targets. This paper will focus on lung tissue repair, regeneration, remodeling, and cell types that may be important to consider in therapeutic interventions and includes a more detailed discussion of the potential targets of current therapeutic attack in pulmonary fibrosis. The discovery that adult bone marrow stem cells can contribute to the formation of differentiated cell types in other tissues, especially after injury, implies that they have the potential to participate in tissue remodeling, and perhaps regeneration. The current promise of the use of adult stem cells for tissue regeneration, and the belief that once irreversibly damaged tissue could be restored to a normal functional capacity using stem cell-based therapy, suggests a novel approach for treatment of diverse chronic diseases. However this optimism is tempered by current evidence that the pathogenesis of pulmonary fibrosis may involve the recruitment of bone marrow-derived fibroblasts, which are the key contributors to the pathogenesis of this chronic progressive disorder. Nevertheless, stem cell-related therapies are widely viewed as promising treatment options for patients suffering from various types of pulmonary diseases. Gender mismatched bone marrow or lung transplant recipients serve as natural populations in which to study the role of bone marrow-derived stem cells in recovery from pulmonary diseases. Understanding the mechanism of recruitment of stem cells to sites of injury, and their involvement in tissue repair, regeneration, and remodeling may offer a novel therapeutic target for developing more effective treatments against this fatal disorder. This article reviews the new concepts in the pathogenesis, current and future treatment options of pulmonary fibrosis, and the recent advances regarding the roles of stem cells in lung tissue repair, regeneration, and remodeling.

Mactinin treatment promotes wound-healing-associated inflammation in urokinase knockout mice.

Mactinin, a 31 kDa fragment from the amino-terminal end of alpha-actinin, is chemotactic for monocytes and can promote monocyte/macrophage maturation. Macrophages are essential for wound healing, in which they play key roles in debridement, angiogenesis, fibroblast proliferation, and collagen metabolism. We have previously determined that urokinase is necessary to form mactinin from extracellular alpha-actinin, which may be present at sites of inflammation as a result of cell movement. Thus, urokinase knockout mice are unable to form mactinin and therefore are an ideal model to study mactinin's effects on wound healing. Saline- and mactinin-treated wounds were analyzed in a subcutaneous sponge wound model in both wild-type and urokinase knockout mice. The wounded urokinase knockout mice had markedly decreased leukocyte infiltration compared with wounded wild-type mice. In addition, production of the proinflammatory cytokine, interleukin-12, and of collagen was also decreased in knockouts. Treatment of knockout mice with mactinin resulted in leukocyte infiltration numbers, interleukin-12 levels, and hydroxyproline measurements similar to those in wild-type mice. The results suggest that impaired wound healing in urokinase-deficient mice can be restored by administration of mactinin.

Induction of p53 by urokinase in lung epithelial cells.

Urokinase plasminogen activator (uPA) is a serine protease that catalyzes the conversion of plasminogen to plasmin. The plasminogen/plasmin system includes the uPA, its receptor, and its inhibitor (plasminogen activator inhibitor-1). Interactions between these molecules regulate cellular proteolysis as well as adhesion, cellular proliferation, and migration, processes germane to the pathogenesis of lung injury and neoplasia. In previous studies, we found that uPA regulates cell surface fibrinolysis by regulating its own expression as well as that of the uPA receptor and plasminogen activator inhibitor-1. In this study, we found that uPA alters expression of the tumor suppressor protein p53 in Beas2B airway epithelial cells in both a time- and concentration-dependent manner. These effects do not require uPA catalytic activity because the amino-terminal fragment of uPA lacking catalytic activity was as potent as two chain active uPA. Single chain uPA also enhanced p53 expression to the same extent as intact two chain active uPA and the amino-terminal fragment. Pretreatment of cells with anti-beta1 integrin antibody blocked uPA-induced p53 expression. uPA-induced p53 expression occurs without increased p53 mRNA expression. However, uPA induced oncoprotein MDM2 in a concentration-dependent manner. uPA-induced p53 expression does not require activation of tyrosine kinases. Inactivation of protein-tyrosine phosphatase SHP-2 inhibits both basal and uPA-induced p53 expression. Plasmin did not alter uPA-mediated p53 expression. The induction of p53 expression by exposure of lung epithelial cells to uPA is a newly recognized pathway by which urokinase may influence the proliferation of lung epithelial cells. This pathway could regulate pathophysiologic alterations of p53 expression in the setting of lung inflammation or neoplasia.

Urokinase-deficient mice fail to generate a type 2 immune response following schistosomal antigen challenge.

Activated lymphocytes express urokinase-type plasminogen activator (uPA). Previous work suggests that uPA modulates T-lymphocyte responses. Mice deficient in uPA (uPA(-/-)) fail to generate type 1 (T1) immune responses during infection with Cryptococcus neoformans. Failure to generate either a T1 or a T2 immune response is not predictive of defects in the alternative response. Conversely, down-regulation of one type of immune response may result in inappropriate overactivation of the other. It is not known whether the immune defect in uPA(-/-) mice affects only T1 responses or whether T2 responses are also impaired. Impairment of both T1 and T2 responses would suggest a global T-cell defect in the absence of uPA. To determine the role of uPA in T2 immune responses, wild-type (WT) and uPA(-/-) mice were primed and challenged with schistosomal egg antigen (SEA). This elicits strong polarization to T2 immune responses in immunocompetent mice. The challenged WT mice developed delayed-type hypersensitivity (DTH) to SEA; high levels of serum immunoglobulin E (IgE); a strong T2 cytokine phenotype with markedly elevated levels of interleukin-4 (IL-4), IL-5, and IL-13; and eosinophil-rich pulmonary granulomas. uPA(-/-) mice failed to develop DTH to SEA; did not polarize Ig production to IgE; did not produce high levels of IL-4, IL-5, or IL-13; and had markedly reduced numbers of granuloma-associated eosinophils. uPA(-/-) mice fail to generate polarized T2 immune responses to a T2-inducing pathogen. These findings, in conjunction with our previous work, demonstrate that mice deficient in uPA have profoundly impaired immunity involving both T1 and T2 polarization and are largely immunologically unresponsive.

Urokinase-type plasminogen activator is required for the generation of a type 1 immune response to pulmonary Cryptococcus neoformans infection.

Urokinase-type plasminogen activator (uPA)(-/-) mice cannot mount protective host defenses during infection with the opportunistic yeast Cryptococcus neoformans (52D). Because effective host defense against C. neoformans requires specific immune responses and the generation of type 1 (T1) cytokines, we determined how the absence of uPA impacts these processes. Wild-type (WT) and uPA(-/-) mice were inoculated with C. neoformans. Macrophage antifungal activity was assessed histologically, T lymphocyte responses in vivo and proliferation in vitro were quantified, and cytokine concentrations were determined by ELISA. uPA(-/-) macrophages have impaired antimicrobial activity. Regional lymph nodes of infected uPA(-/-) mice contained fewer cells than WT, suggesting impaired T cell proliferation in response to the pathogen in vivo. In vitro, uPA(-/-) T lymphocytes had impaired proliferative responses to C. neoformans rechallenge compared with WT. Infected WT mice generated T1 cytokines in the lung, characterized by high levels of IFN-gamma and IL-12. uPA(-/-) mice had decreased levels of IFN-gamma and IL-12, and increased IL-5, a type 2 cytokine. In the absence of uPA, the cytokine profile of regional lymph nodes shifted from a T1 pattern characterized by IFN-gamma and IL-2 to a weak, nonpolarized response. We conclude that in the absence of uPA, lymphocyte proliferative responses are diminished, and mice fail to generate protective T1 cytokines, resulting in impaired antimicrobial activity. This study provides novel evidence that uPA is a critical modulator of immune responses and of immune cell effector functions in vivo.

Urokinase-type plasminogen activator potentiates lipopolysaccharide-induced neutrophil activation.

Urokinase plasminogen activator (uPA) is a serine protease that catalyzes the conversion of plasminogen to plasmin. Although increased circulating levels of uPA are present in endotoxemia and sepsis, conditions in which activated neutrophils contribute to the development of acute organ dysfunction, the ability of uPA to participate directly in LPS-induced neutrophil activation has not been examined. In the present experiments, we show that uPA can enhance activation of neutrophils exposed to submaximal stimulatory doses of LPS. In particular, uPA increased LPS-induced activation of intracellular signaling pathways, including Akt and c-Jun N-terminal kinase, nuclear translocation of the transcriptional regulatory factor NF-kappa B, and expression of proinflammatory cytokines, including IL-1 beta, macrophage-inflammatory protein-2, and TNF-alpha. There was no effect of uPA on LPS-induced activation of p38 mitogen-activated protein kinase in neutrophils. Transgenic mice unable to produce uPA (uPA(-/-)) were protected from endotoxemia-induced lung injury, as determined by development of lung edema, pulmonary neutrophil accumulation, lung IL-1 beta, macrophage-inflammatory protein-2, and TNF-alpha cytokine levels. These results demonstrate that uPA can potentiate LPS-induced neutrophil responses and also suggest that such effects are sufficiently important in vivo to play a major contributory role in neutrophil-mediated inflammatory responses, such as the development of acute lung injury.

Pericellular proteolysis by leukocytes and tumor cells on substrates: focal activation and the role of urokinase-type plasminogen activator.

Previous studies have shown that the urokinase-type plasminogen activator receptor (uPAR) is localized to the adherence sites of leukocytes and tumor cells suggesting that pericellular proteolysis may accompany focal activation of adherence. To assess for focused pericellular proteolytic activity, we prepared two-dimensional substrates coated with FITC-casein or Bodipy FL-BSA. These molecules are poorly fluorescent, but become highly fluorescent after proteolytic degradation. Fluorescent peptide products were observed at adherence sites of stationary human neutrophils and at lamellipodia of polarized neutrophils. During cell migration, multiple regions of proteolysis appeared sequentially beneath the cell. Similarly, proteolytic action was restricted to adherence sites of resting HT1080 tumor cells but localized to the invadopodia of active cells. Using an extracellular fluorescence quenching method, we demonstrate that these fluorescent peptide products are extracellular. The uPA/uPAR system played an important role in the observed proteolytic activation. Plasminogen activator inhibitor-1 significantly reduced focal proteolysis. Sites of focal proteolysis matched the membrane distribution of uPAR. When uPA was dissociated from uPAR by acid washing, substantially reduced pericellular proteolysis was found. uPAR-negative T47D tumor cells did not express significant levels of substrate proteolysis. However, transfectant clones expressing uPAR (for example, T47D-26) displayed high levels of fluorescence indicating proteolysis at adherence sites. To provide further evidence for the role of the uPA/uPAR system in pericellular proteolysis, peritoneal macrophages from uPA knock-out (uPA-/-) and control (uPA+/+) mice were studied. Pericellular proteolysis was dramatically reduced in uPA-negative peritoneal macrophages. Thus, we have: (1). developed a novel methodology to detect pericellular proteolytic function, (2). demonstrated focused activation of proteolytic enzymatic activity in several cell types, (3). demonstrated its usefulness in real-time studies of cell migration, and (4). showed that the uPA/uPAR system is an important contributor to focal pericellular proteolysis.