Validation and shortcomings of the most common mouse model of chronic rhinosinusitis with nasal polyps

BACKGROUND

Chronic rhinosinusitis (CRS) is a highly prevalent airway disease worldwide. Whereas eosinophilic CRS with nasal polyps (eCRSwNP) represents its most severe phenotype, pathogenic mechanisms remain poorly understood despite a wide spectrum of in vitro and in vivo experimental models. A mouse model of experimental ovalbumin (OVA)-induced airway allergy with coadministration of Staphylococcus aureus enterotoxin B (SEB) has been widely used to study eosinophilic eCRSwNP. This study revisits the features of this model and its suitability for studying eCRS.

METHODOLOGY

We implemented the most used eCRSwNP mouse model based on OVA+SEB intranasal challenges. Readouts including inflammatory features by (immuno)histology of the sinonasal epithelium (NP formation, eosinophils, epithelial and basement membrane thickness, fibrosis, goblet cells, Charcot-Leyden crystals (CLC)-like, tight junctions) and IgE production by enzyme-linked immunosorbent assay (ELISA), were compared to features of the corresponding human disease.

RESULTS

The OVA+SEB model induced eosinophilic inflammation of upper and lower airways, with epithelial and basement membrane thickening, goblet cell hyperplasia and subepithelial fibrosis in the sinuses, along increased IgE production. Except local IgE in nasal lavage (NL), which was only increased in OVA+SEB group, all other features did not differ between OVA and OVA+SEB groups. Macro- or microscopic NP were not detected.

CONCLUSIONS

With the notable exception of local IgE production, the addition of SEB did not induce additional inflammatory or structural change in the sinuses from mice exposed to and challenged with OVA. This model might represent a model for severe upper airway allergy rather than a specific model of human eCRSwNP.

The memory of airway epithelium damage in smokers and COPD patients

Chronic obstructive pulmonary disease (COPD), a devastating and irreversible lung disease, causes structural and functional defects in the bronchial epithelium, the (ir)reversibility of which remains unexplored in vitro. This study aimed to investigate the persistence of COPD-related epithelial defects in long-term airway epithelial cultures derived from non-smokers, smokers, and COPD patients. Barrier function, polarity, cell commitment, epithelial-to-mesenchymal transition, and inflammation were evaluated and compared with native epithelium characteristics. The role of inflammation was explored using cytokines. We show that barrier dysfunction, compromised polarity, and lineage abnormalities observed in smokers and COPD persisted for up to 10 wk. Goblet cell hyperplasia was associated with recent cigarette smoke exposure. Conversely, increased IL-8/CXCL-8 release and abnormal epithelial-to-mesenchymal transition diminished over time. These ex vivo observations matched surgical samples' abnormalities. Cytokine treatment induced COPD-like changes in control cultures and reactivated epithelial-to-mesenchymal transition in COPD cells. In conclusion, these findings suggest that the airway epithelium of smokers and COPD patients retains a multidimensional memory of its original state and previous cigarette smoke-induced injuries, maintaining these abnormalities for extended periods.

Restin protein expression in non-small cell lung cancer

BACKGROUND

Restin is a member of the melanoma-associated antigen (MAGE) superfamily. Its expression has been reported to be up- or downregulated in cancer. Preclinical data suggest it is a tumor suppressor. In this study, we aimed to evaluate restin expression and prognostic value in non-small cell lung cancer (NSCLC).

METHODS

Restin expression was analyzed by immunohistochemistry in three tissue microarrays consisting of formalin-fixed/paraffin-embedded NSCLC specimens from 113 patients, represented in triplicate. Restin staining H-score was the result of the staining intensity (0-no, 1-weak, 2-moderate, and 3-strong) multiplied by the percentage of stained tumor cells; it was defined as low if 1-100, moderate if 101-200, and strong if 201-300. Haverage-score was the average H-score in the triplicate. Restin Haverage-scores were tested for correlations with clinical and pathological characteristics and patient outcome.

RESULTS

Restin expression was localized to the cytoplasm, with nuclear enhancement, of 112/113 (99.1%) NSCLCs. Restin Haverage-scores were 0 in 1/113 (0.88%), low in 15/113 (13.3%), moderate in 48/113 (42.5%), and strong in 49/113 (43.4%) NSCLCs. Restin Haverage-scores did not correlate with NSCLC histological subtype, disease stage, recurrence/progression-free, or overall survival.

CONCLUSION

Restin is moderately to strongly expressed in the majority of NSCLC tumors but its expression has no prognostic value in patients with NSCLC.

[Potential therapeutic implication of focal adhesion kinase in small-cell lung cancer]

The molecular steps leading to small cell lung cancer (SCLC) development and progression are still poorly understood, resulting in the absence of targeted therapy and an extremely poor prognosis. Activation of Focal Adhesion Kinase (FAK) plays a key role in the invasive behavior of this cancer in vitro. Our hypothesis is that FAK could be a therapeutic target in SCLC. Our work aims to describe a mouse model to study the role of FAK and the antitumoral potential of its inhibition in SCLC in vivo.

Disruption of GCN2 Pathway Aggravates Vascular and Parenchymal Remodeling during Pulmonary Fibrosis

Pulmonary fibrosis (PF) and pulmonary hypertension (PH) are chronic diseases of the pulmonary parenchyma and circulation, respectively, which may coexist, but underlying mechanisms remain elusive. Mutations in the GCN2 (general control nonderepressible 2) gene (EIF2AK4 [eukaryotic translation initiation factor 2 alpha kinase 4]) were recently associated with pulmonary veno-occlusive disease. The aim of this study is to explore the involvement of the GCN2/eIF2α (eukaryotic initiation factor 2α) pathway in the development of PH during PF, in both human disease and in a laboratory animal model. Lung tissue from patients with PF with or without PH was collected at the time of lung transplantation, and control tissue was obtained from tumor resection surgery. Experimental lung disease was induced in either male wild-type or EIF2AK4-mutated Sprague-Dawley rats, randomly receiving a single intratracheal instillation of bleomycin or saline. Hemodynamic studies and organ collection were performed 3 weeks after instillation. Only significant results (P < 0.05) are presented. In PF lung tissue, GCN2 protein expression was decreased compared with control tissue. GCN2 expression was reduced in CD31⁺ endothelial cells. In line with human data, GCN2 protein expression was decreased in the lung of bleomycin rats compared with saline. EIF2AK4-mutated rats treated with bleomycin showed increased parenchymal fibrosis (hydroxyproline concentrations) and vascular remodeling (media wall thickness) as well as increased right ventricular systolic pressure compared with wild-type animals. Our data show that GCN2 is dysregulated in both humans and in an animal model of combined PF and PH. The possibility of a causative implication of GCN2 dysregulation in PF and/or PH development should be further studied.

Bleomycin-induced lung injury: Revisiting an old tool to model group III PH associated with pulmonary fibrosis

Pulmonary hypertension (PH) is a chronic disorder of the pulmonary circulation that often associates with other respiratory diseases (i.e., group III PH), leading to worsened symptoms and prognosis, notably when combined with interstitial lung diseases such as pulmonary fibrosis (PF). PH may lead to right ventricular (RV) failure, which accounts for a substantial part of the mortality in chronic lung disease patients. The disappointing results of pulmonary arterial hypertension (PAH)-related therapies in patients with PF emphasize the need to better understand the pathophysiologic mechanisms that drive PH development and progression in this specific setting. In this work, we validated an animal model of group III PH associated with PF (PH-PF), by using bleomycin (BM) intratracheal instillation and characterizing the nature of induced lung and vascular remodeling, including the influence on RV structure and function. To our knowledge, this is the first work describing this dose of BM in Sprague Dawley rats and the effects upon the heart and lungs, using different techniques such as echocardiography, heart catheterization, and histology. Our data shows the successful implementation of a rat model that mimics combined PF-PH, with most features seen in the equivalent human disease, such as lung and arterial remodeling, increased mPAP and RV dysfunction.

Loss of ciliated cells and altered airway epithelial integrity in cystic fibrosis

BACKGROUND

In cystic fibrosis, the respiratory epithelium is the target tissue of both the genetic abnormality of the disease and of external aggressions, notably by pathogens (Pseudomonas aeruginosa). A detailed characterisation of the cystic fibrosis bronchial epithelium is however lacking, as most previous studies focused on the nasal epithelium or on cell lines. This study aimed to characterise the abnormal phenotype and epithelial-to-mesenchymal transition in cystic fibrosis bronchial epithelium and to evaluate in cell cultures whether abnormalities persist ex vivo.

METHODS

Explant lung tissues (n = 44) were assessed for bronchial epithelial cell phenotyping by immunostaining. Human bronchial epithelial cells were derived from basal cells isolated from cystic fibrosis patients or control donors and cultured in air-liquid interface for 2, 4 or 6 weeks.

RESULTS

Enhanced mucin 5AC and decreased β-tubulin expression were observed in cystic fibrosis airways reflecting a decreased ciliated/goblet cell ratio, associated with increased number of vimentin-positive cells, indicating epithelial-to-mesenchymal transition process. These features were recapitulated in vitro, in cystic fibrosis-derived reconstituted epithelium. However, they were not induced by CFTR inhibition or Pseudomonas infection, and most abnormalities tended to disappear in long-term culture (6 weeks) except for increased fibronectin release, an epithelial-to-mesenchymal transition marker.

CONCLUSIONS

This study provides new insights into airway epithelial changes in cystic fibrosis, which are imprinted through an acquired mechanism that we could not relate to CFTR function.

[Immunotherapy for head and neck squamous cell carcinoma]

Current recommendations for systemic treatments of head and neck squamous cell carcinoma have been significantly modified with the advent of immunotherapy for a majority of these cancers. Indeed, immune checkpoint inhibitors are now recommended in metastatic disease and in locoregional recurrence not amenable to a local treatment. PD-L1 positive tumours are eligible for immunotherapy in first line and immunotherapy is also available in second line, after failure of platinum based chemotherapy, regardless of PD-L1 expression. Ongoing clinical trials are exploring the role of immune checkpoint inhibitors in the adjuvant setting as well as with radiotherapy as definitive treatment. Immunotherapy has changed the treatment landscape and has improved the prognosis of patients with head and neck squamous cell carcinoma.

[Immune-related adverse events]

Immunotherapy has revolutionized cancer management in recent years and is affecting more and more patients. Immunotherapy side effects are specific, immune-related, and their early recognition and management are essential. Here we describe the main adverse effects of immunotherapy and their general principles of management.

Increased Expression and Activation of FAK in Small-Cell Lung Cancer Compared to Non-Small-Cell Lung Cancer

INTRODUCTION

Focal adhesion kinase (FAK) plays a crucial role in cancer development and progression. FAK is overexpressed and/or activated and associated with poor prognosis in various malignancies. However, in lung cancer, activated FAK expression and its prognostic value are unknown.

METHODS

FAK and activated FAK (phospho-FAK Y397) expressions were analyzed by multiplex immunofluorescence staining in formalin-fixed paraffin-embedded tissues from 95 non-small-cell lung cancer (NSCLC) and 105 small-cell lung cancer (SCLC) patients, and 37 healthy donors. The FAK staining score was defined as the percentage (%) of FAK-stained tumor area multiplied by (×) FAK mean intensity and phospho-FAK staining score as the (% of phospho-FAK-stained area of low intensity × 1) + (% of phospho-FAK-stained area of medium intensity × 2) + (% of the phospho-FAK-stained area of high intensity × 3). FAK and phospho-FAK staining scores were compared between normal, NSCLC, and SCLC tissues. They were also tested for correlations with patient characteristics and clinical outcomes.

RESULTS

The median follow-up time after the first treatment was 42.5 months and 6.4 months for NSCLC and SCLC patients, respectively. FAK and phospho-FAK staining scores were significantly higher in lung cancer than in normal lung and significantly higher in SCLC compared to NSCLC tissues (p < 0.01). Moreover, the ratio between phospho-FAK and FAK staining scores was significantly higher in SCLC than in NSCLC tissues (p < 0.01). However, FAK and activated FAK expression in lung cancer did not correlate with recurrence-free and overall survival in NSCLC and SCLC patients.

CONCLUSIONS

Total FAK and activated FAK expressions are significantly higher in lung cancer than in normal lung, and significantly higher in SCLC compared to NSCLC, but are not prognostic biomarkers in this study.

Bronchial Epithelial IgA Secretion Is Impaired in Asthma. Role of IL-4/IL-13

RATIONALE

Asthma is associated with increased lung IgE production, but whether the secretory IgA system is affected in this disease remains unknown.

OBJECTIVES

We explored mucosal IgA transport in human asthma and its potential regulation by T-helper cell type 2 inflammation.

METHODS

Bronchial biopsies from asthma and control subjects were assayed for bronchial epithelial polymeric immunoglobulin receptor (pIgR) expression and correlated to T-helper cell type 2 biomarkers. Bronchial epithelium reconstituted in vitro from these subjects, on culture in air-liquid interface, was assayed for pIgR expression and regulation by IL-4/IL-13.

MEASUREMENTS AND MAIN RESULTS

Downregulation of pIgR protein was observed in the bronchial epithelium from patients with asthma (P = 0.0002 vs. control subjects). This epithelial defect was not observed ex vivo in the cultured epithelium from patients with asthma. Exogenous IL-13 and IL-4 could inhibit pIgR expression and IgA transcytosis. Mechanistic experiments showed that autocrine transforming growth factor-β mediates the IL-4/IL-13 effect on the pIgR, with a partial contribution of upregulated transforming growth factor-α/epidermal growth factor receptor.

CONCLUSIONS

This study shows impaired bronchial epithelial pIgR expression in asthma, presumably affecting secretory IgA-mediated frontline defense as a result of type 2 immune activation of the transforming growth factor pathway.

Therapeutic Potential of Focal Adhesion Kinase Inhibition in Small Cell Lung Cancer

Small cell lung cancer (SCLC) has a poor prognosis. Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase regulating cell proliferation, survival, migration, and invasion, which is overexpressed and/or activated in several cancers, including SCLC. We wanted to determine whether FAK contributes to SCLC aggressive behavior. We first evaluated the effect of FAK small-molecule inhibitor PF-573,228 in NCI-H82, NCI-H146, NCI-H196, and NCI-H446 SCLC cell lines. PF-573,228 (0.1-5 μmol/L) inhibited FAK activity by decreasing phospho-FAK (Tyr397), without modifying total FAK expression. PF-573,228 decreased proliferation, decreased DNA synthesis, induced cell-cycle arrest in G₂-M phases, and increased apoptosis in all cell lines. PF-573,228 also decreased motility in adherent cell lines. To make sure that these effects were not off-target, we then used a genetic method to inhibit FAK in NCI-H82 and NCI-H446, namely stable transduction with FAK shRNA and/or FAK-related nonkinase (FRNK), a splice variant lacking the N-terminal and kinase domains. Although FAK shRNA transduction decreased total and phospho-FAK (Tyr397) expression, it did not affect proliferation, DNA synthesis, or progression through cell cycle. However, restoration of FAK-targeting (FAT) domain (attached to focal adhesion complex where it inhibits pro-proliferative proteins such as Rac-1) by FRNK transduction inhibited proliferation, DNA synthesis, and induced apoptosis. Moreover, although FAK shRNA transduction increased active Rac1 level, FRNK reexpression in cells previously transduced with FAK shRNA decreased it. Therefore, FAK appears important in SCLC biology and targeting its kinase domain may have a therapeutic potential, while targeting its FAT domain should be avoided to prevent Rac1-mediated protumoral activity.

Imprinting of the COPD airway epithelium for dedifferentiation and mesenchymal transition

In chronic obstructive pulmonary disease (COPD), epithelial changes and subepithelial fibrosis are salient features in conducting airways. Epithelial-to-mesenchymal transition (EMT) has been recently suggested in COPD, but the mechanisms and relationship to peribronchial fibrosis remain unclear. We hypothesised that de-differentiation of the COPD respiratory epithelium through EMT could participate in airway fibrosis and thereby, in airway obstruction.

Surgical lung tissue and primary broncho-epithelial cultures (in air–liquid interface (ALI)) from 104 patients were assessed for EMT markers. Cell cultures were also assayed for mesenchymal features and for the role of transforming growth factor (TGF)-β1.

The bronchial epithelium from COPD patients showed increased vimentin and decreased ZO-1 and E-cadherin expression. Increased vimentin expression correlated with basement membrane thickening and airflow limitation. ALI broncho-epithelial cells from COPD patients also displayed EMT phenotype in up to 2 weeks of culture, were more spindle shaped and released more fibronectin. Targeting TGF-β1 during ALI differentiation prevented vimentin induction and fibronectin release.

In COPD, the airway epithelium displays features of de-differentiation towards mesenchymal cells, which correlate with peribronchial fibrosis and airflow limitation, and which are partly due to a TGF-β1-driven epithelial reprogramming.

Increased IgA production by B-cells in COPD via lung epithelial interleukin-6 and TACI pathways

Despite their relevance to mucosal defense, production of IgA and the function of lung B-cells remain unknown in chronic obstructive pulmonary disease (COPD). We assessed IgA synthesis in the lungs of COPD (n=28) and control (n=21) patients, and regulation of B-cells co-cultured with in vitro-reconstituted airway epithelium. In COPD lung tissue, synthesis of IgA1 was increased, which led to its accumulation in subepithelial areas. In vitro, the COPD bronchial epithelium imprinted normal human B-cells for increased production of IgA (mainly IgA1) and maturation into CD38(+) plasma cells. These effects were associated with upregulation of TACI (transmembrane activator and CAML interactor) and were observed under resting conditions, while being partly inhibited upon stimulation with cigarette smoke extract. Interleukin (IL)-6 and BAFF (B-cell activating factor)/APRIL (a proliferation-inducing ligand) were upregulated in the COPD epithelium and lung tissue, respectively; the IgA-promoting effect of the COPD bronchial epithelium was inhibited by targeting IL-6 and, to a lower extent, by blocking TACI. These data show that in COPD, the bronchial epithelium imprints B-cells with signals promoting maturation into IgA-producing plasma cells through the action of two epithelial/B-cell axes, namely the IL-6/IL-6 receptor and BAFF-APRIL/TACI pathways, while cigarette smoke partly counteracts this IgA-promoting effect.

Features of mesenchymal transition in the airway epithelium from chronic rhinosinusitis

BACKGROUND

Chronic rhinosinusitis (CRS) defines a group of disorders characterized by persistent inflammation of the sinonasal tract. Epithelial changes and structural remodelling are present, but whether epithelial differentiation is altered remains uncertain.

METHODS

To evaluate the differentiation state of the sinonasal epithelium in CRS, sinonasal biopsies from patients with CRS with nasal polyps (CRSwNP) or CRS without nasal polyps (CRSsNP), or with allergic rhinitis (AR), as compared to controls, were processed by immunohistochemistry and RT-qPCR for terminal differentiation (E-cadherin, high molecular weight cytokeratins (Hmw CK) and CK5, vimentin) and lineage differentiation (ß-tubulin IV+ ciliated cells, MUC5AC+ goblet cells, p63 + basal cells). Findings were correlated with subepithelial fibrosis and clinical CT score.

RESULTS

Expression of E-cadherin was decreased at protein and mRNA levels in CRSwNP and CRSsNP, as compared to controls. Staining for Hmw CKs was also reduced in CRSwNP and CRSsNP, and CK5 mRNA was decreased in CRSwNP. These features were not due to changes in lineage specification, but associated with increases in vimentin-expressing epithelial cells. In addition, vimentin expression correlated with the basement membrane thickening and with CT score, as well as with tissue eosinophils.

CONCLUSION

Features of epithelial dedifferentiation towards a mesenchymal phenotype are observed in CRSwNP and CRSsNP and correlate with airway fibrosis and inflammation.

Downregulation of polymeric immunoglobulin receptor and secretory IgA antibodies in eosinophilic upper airway diseases

BACKGROUND

Immunoglobulin (Ig) A represents a first-line defence mechanism in the airways, but little is known regarding its implication in upper airway disorders. This study aimed to address the hypothesis that polymeric Ig receptor (pIgR)-mediated secretory IgA immunity could be impaired in chronic upper airway diseases.

METHODS

Nasal and ethmoidal biopsies, as well as nasal secretions, were collected from patients with chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) or without nasal polyps (CRSsNP), allergic rhinitis (AR) and controls, and assayed for IgA1/IgA2 synthesis, pIgR expression, production of secretory component (SC), IgA and relevant IgA antibodies, and correlated with local eosinophils and inflammatory features (IL-12, IL-13 and ECP).

RESULTS

pIgR expression was decreased in the ethmoidal mucosa in patients with CRSwNP (P = 0.003) and in AR (P = 0.006). This pIgR defect was associated with reduced levels of SC (P = 0.007) and IgA antibodies to Staphylococcus aureus enterotoxin B (SAEB) (P = 0.003) in nasal secretions from patients with CRSwNP, and with increased IgA deposition in subepithelial areas. pIgR downregulation was selectively observed in patients with tissue eosinophilia, whilst no clear relation to smoking history was observed.

CONCLUSION

Epithelial pIgR expression is decreased in patients with CRSwNP and AR and results in decreased SC and IgA antibodies to certain bacterial antigens (SAEB) in nasal secretions of patients with CRSwNP in parallel to subepithelial accumulation of IgA. This defect in mucosal immunity is associated with eosinophilic, Th2-related inflammation.

Platelet-derived growth factor-producing CD4+ Foxp3+ regulatory T lymphocytes promote lung fibrosis

RATIONALE

There is evidence that CD4(+) effector T lymphocytes (T eff) participate in the development of lung fibrosis, but the role of their CD4(+) regulatory T-cell (T reg) counterparts remains to be determined.

OBJECTIVES

To elucidate the contribution of T reg cells in a mouse model of lung fibrosis induced by silica (SiO(2)) particles.

METHODS

Lung T reg and T eff cells purified from SiO(2)-treated Foxp3-GFP transgenic mice were cocultured with naive lung fibroblasts or transferred to the lungs of healthy mice. DEREG mice, which express the diphtheria toxin receptor under the control of the foxp3 gene, were used to deplete T reg cells during fibrogenesis.

MEASUREMENTS AND MAIN RESULTS

CD4(+) Foxp3(+) T reg cells were persistently recruited in the lungs in response to SiO(2). T reg accumulation paralleled the establishment of pulmonary immunosuppression and fibrosis. T reg cells highly expressed platelet-derived growth factor (PDGF)-B via a TGF-β autocrine signaling pathway, directly stimulated fibroblast proliferation in vitro, and increased lung collagen deposition upon transfer in the lung of naive mice. The direct profibrotic effects of T reg cells were abolished by the inhibitor of the PDGF-B/TGF-β signaling pathway, imatinib mesylate. Neutralization of T reg-immunosuppressive activity resulted in enhanced accumulation of T eff cells and IL-4-driven pulmonary fibrogenesis, further demonstrating that T reg cells control T eff cell functions during inflammatory fibrosis.

CONCLUSIONS

Our study indicates that T reg cells contribute to lung fibrosis by stimulating fibroblasts through the secretion of PDGF-B in noninflammatory conditions and regulate detrimental T eff cell activities during inflammation-related fibrosis.

Cartilage matrix changes in the developing epiphysis: early events on the pathway to equine osteochondrosis?

REASONS FOR PERFORMING STUDY

The earliest osteochondrosis (OC) microscopic lesion reported in the literature was present in the femorotibial joint of a 2-day-old foal suggesting that OC lesions and factors initiating them may arise prior to birth.

OBJECTIVE

To examine the developing equine epiphysis to detect histological changes that could be precursors to OC lesions.

METHODS

Osteochondral samples from 21 equine fetuses and 13 foals were harvested from selected sites in the scapulohumeral, humeroradial, metacarpophalangeal, femoropatellar, femorotibial, tarsocrural and metatarsophalangeal joints. Sections were stained with safranin O and picrosiruis red to assess cartilage changes and structural arrangement of the collagen matrix.

RESULTS

Extracellular matrix changes observed included perivascular areas of paleness of the proteoglycan matrix associated with hypocellularity and, sometimes, necrotic chondrocytes. These changes were most abundant in the youngest fetuses and in the femoropatellar/femorotibial (FP/FT) joints. Indentations of the ossification front were also observed in most specimens, but, most frequently, in scapulohumeral and FP/FT joints. A cartilage canal was almost always present in these indentations. The vascular density of the cartilage was higher in the youngest fetuses. In these fetuses, the most vascularised joints were the metacarpo- and metatarsophalangeal joints but their cartilage canals regressed quickly. After birth, the most vascularised cartilage was present in the FP/FT joint. Articular cartilage differentiated into 4 zones early in fetal life and the epiphyseal cartilage also had a distinct zonal cartilage structure. A striking difference was observed in the collagen structure at the junction of the proliferative and hypertrophic zones where OCD lesions occur.

CONCLUSION

Matrix and ossification front changes were frequently observed and significantly associated with cartilage canals suggesting that they may be physiological changes associated with matrix remodelling and development. The collagen structure was variable through the growing epiphysis and a differential in biomechanical properties at focal sites may predispose them to injury.

Neuronal viability is controlled by a functional relation between synaptic and extrasynaptic NMDA receptors

N-methyl-D-aspartate receptors (NMDARs) are critical for synaptic plasticity that underlies learning and memory. But, they have also been described as a common source of neuronal damage during stroke and neurodegenerative diseases. Several studies have suggested that cellular location of NMDARs (synaptic or extrasynaptic) is a key parameter controlling their effect on neuronal viability. The aim of the study was to understand the relation between these two pools of receptors and to determine their implication in both beneficial and/or deleterious events related to NMDAR activation. We demonstrated that selective extrasynaptic NMDAR activation, as well as NMDA bath application, does not activate extracellular signal-regulated kinase (ERK) pathways, but induces mitochondrial membrane potential breakdown and triggers cell body and dendrite damages, whereas synaptic NMDAR activation is innocuous and induces a sustained ERK activation. The functional dichotomy between these two NMDAR pools is tightly controlled by glutamate uptake systems. Finally, we demonstrated that the only clinically approved NMDAR antagonist, memantine, preferentially antagonizes extrasynaptic NMDARs. Together, these results suggest that extrasynaptic NMDAR activation contributes to excitotoxicity and that a selective targeting of the extrasynaptic NMDARs represents a promising therapeutic strategy for brain injuries.

Evaluation of mycobacteria growth indicator tube for direct and indirect drug susceptibility testing of Mycobacterium tuberculosis from respiratory specimens in a Siberian prison hospital

The manual Mycobacteria Growth Indicator Tube (MGIT) method was evaluated for performing direct and indirect drug susceptibility testing (DST) of Mycobacterium tuberculosis for isoniazid and rifampin on 101 strongly smear-positive sputum specimens in a Siberian prison hospital. Using the indirect method of proportion (MOP) as the "gold standard," the accuracies of isoniazid and rifampin susceptibility testing by the direct MGIT system were 97.0 and 94.1%, respectively. The accuracy of the indirect MGIT system was 98.0% for both drugs. The turnaround times from specimen processing to reporting of the DST results ranged between 4 and 23 (mean, 9.2) days by the direct MGIT method, 9 and 30 (mean, 15.3) days by the indirect MGIT method, and 26 and 101 (mean, 59.6) days by the indirect MOP. MGIT appears to be a reliable, rapid, and convenient method for performing direct and indirect DSTs in low-resource settings, but further studies are required to refine the direct DST protocol. Cost is the only factor prohibiting widespread implementation of MGIT.

Uptake and intracellular fate of polyethylenimine in vivo

Branched polyamines are extensively used as nonviral vectors for plasmid DNA in transfection experiments. Moreover, recently it has been shown that these compounds are able to eliminate prions from infected cells in cultures. It has been proposed that in both cases endosomes or lysosomes are the site of action. This raises the question of how these molecules are taken up by the cells and what is their intracellular fate. In the work presented here, the question has been addressed by investigating the uptake and the intracellular distribution of branched polyethyleneimine (25 kD) by centrifugation methods. The polyamine was labelled with (125)I-tyramine cellobiose and injected to the rat. The radioactive polymer is taken up after injection into the liver, kidney, spleen, and lungs and remains in these organs for many days. In the liver, it is found mainly in the hepatocytes. Intracellular distribution of radioactivity present in that organ was investigated by differential and isopycnic centrifugations. Early after injection, radioactivity exhibits a distribution pattern similar to that of alkaline phosphodiesterase, a plasma membrane marker. Later, the distribution pattern becomes similar to that of cathepsin C, a lysosomal enzyme. Radioactivity and hydrolase distributions in a sucrose gradient are similarly modified by a pretreatment of the rat with Triton-WR1339, a specific density perturbant of lysosomes. These results indicate that polyethyleneimine is endocytosed and reaches lysosomes. For many days it persists in these organelles probably due to its resistance to lysosomal hydrolases.

The Bacillus stearothermophilus argCJBD operon harbours a strong promoter as evaluated in Escherichia coli cells

We have shown that the B. stearothermophilus argCJBD genes form a single operon. In B. stearothermophilus, a specific repressor governs operon expression by binding to the argCo operator site overlapping the Parg promoter sequence (Dion et al., 1997). Therefore, the enzymatic and transcriptional analyses performed in this work did not reflect the potential strength of Parg in the native host. For evaluation of the Parg promoter strength, E. coli was used as a host since its own ArgR repressor does not interact with the B. stearothermophilus heterologous operator. Parg-promoted argC gene expression dramatically increased, reaching up to 38% of the total protein in E. coli cells. An AT-rich sequence upstream of a -35 site of Parg was found to be indispensable for the promoter strength. Plasmids carrying the B. stearothermophilus argCJBD operon linked with its Parg/argCo region were unstable in E. coli. Stabilization of plasmids was achieved by repression of B. stearothermophilus arg genes through the action of the B. subtilis AhrC repressor.

Two amino acid amidohydrolase genes encoding L-stereospecific carbamoylase and aminoacylase are organized in a common operon in Bacillus stearothermophilus

The L-carbamoylase gene (amaB) upstream of the previously detected L-aminoacylase gene (amaA) in the Bacillus stearothermophilus NCIB8224 strain was identified in this study. The amaB and amaA genes are cotranscribed as a single mRNA from the same transcriptional start. The two-ama-gene operon is conserved in B. stearothermophilus strains. A cross-activity of L-carbamoylase towards respective substrates for L-aminoacylase supports the hypothesis of a common ancestor for both amino acid amidohydrolase genes.

Flow cytofluorimetric analysis of young and senescent human erythrocytes probed with lectins. Evidence that sialic acids control their life span

Comparing the properties of 'young' and senescent ('aged') O+ erythrocytes isolated by applying ultracentrifugation in a self-forming Percoll gradient, we demonstrate that the sialic acids of membrane glycoconjugates control the life span of erythrocytes and that the desialylation of glycans is responsible for the clearance of the aged erythrocytes. This capture is mediated by a beta-galactolectin present in the membrane of macrophages. The evidence supporting these conclusions is as follows: (1) Analysis by flow cytofluorimetry of the binding of fluorescein isothiocyanate labelled lectins specific for sialic acids shows that the aged erythrocytes bind less WGA, LPA, SNA and MAA than young erythrocytes. The binding of DSA and LCA is not modified. On the contrary, the number of binding sites of UEA-I specific for O antigen and of AAA decreases significantly. PNA and GNA do not bind to erythrocytes. (2) RCA120 as well as Erythrina cristagalli and Erythrina corallodendron lectins specific for terminal beta-galactose residues lead to unexpected and unexplained results with a decrease in the number of lectin binding sites associated with increasing desialylation. (3) The glycoconjugates from the old erythrocytes incorporate more sialic acid than the young cells. This observation results from the determination of the rate of transfer by alpha-2,6-sialyltransferase of fluorescent or radioactive N-acetylneuraminic acid, using as donors CMP-9-fluoresceinyl-NeuAc and CMP-[14C]-NeuAc, respectively. (4) Microscopy shows that the old erythrocytes are captured preferentially by the macrophages relative to the young ones. Fixation of erythrocytes by the macrophage membrane is inhibited by lactose, thus demonstrating the involvement of a terminal beta-galactose specific macrophage lectin. (5) Comparative study of the binding of WGA, LPA, SNA and MAA to the aged erythrocytes and to the in vitro enzymatically desialylated erythrocytes shows that the desialylation rate of aged cells is low but sufficient to lead to their capture by the macrophages.

Expression of the lactotransferrin receptor during the differentiation process of the megakaryocyte Dami cell line

In order to determine whether the human lactotransferrin receptor recently described on platelets was also present on hematopoietic precursors, we investigated its presence and characteristics on the megakaryocytic Dami cell line. The reversible binding of human 5-(([2-(carbo(hydrazino)methyl]thio)acetyl)aminofluorescein-labele d lactotransferrin showed that such a receptor was only present on the subpopulation of the largest cells. The increase in numbers of large cells during culture was paralleled by a concurrent increase in lactotransferrin receptor positive cells. Scatchard analysis of the binding of [125I]-labeled lactotransferrin showed that a single affinity class of binding site was present (Kd = 446 +/- 40 nM) and that there were 52 +/- 3 x 10(5) sites per cell. The mouse monoclonal antibody DP5B3G10, specific for the human lactotransferrin receptor, allowed its characterization as a 105 kDa protein on Western blots. The same monoclonal antibody was used to separate the small and large cell subpopulations of Dami cells by panning. Separate culture of the small cells showed that the receptor appeared prior to and independent from endomitosis. In contrast, GPIb was expressed only by large megakaryocytes. The use of conditioned medium from cultures of whole Dami cell populations indicated that a soluble factor is involved in differentiation, but not in the appearance of the lactotransferrin receptor.

Characterization of lactotransferrin receptor in epithelial cell lines from non-malignant human breast, benign mastopathies and breast carcinomas

The aim of this study was to investigate the presence of lactotransferrin receptor on breast non-malignant SV-40 immortalized cells (HBL100 and NB54T), benign mastopathy immortalized cells (NPM14T and NPM21T1), hst oncogene transformed HBL100 cell line (tumorigenic HH9 cells) and breast carcinoma cells (T47D, MCF7, VHB1, BT20 and MDA-MB 231). Flow cytometry analyses of the reversible binding of lactotransferrin labeled on its glycan moiety with fluorescein indicate, for the first time, that all these epithelial breast cell lines, express a specific lactotransferrin receptor. The binding parameters of [125I]-lactotransferrin to non-malignant cells, hst oncogene transformed cells and benign mastopathy cells are of the same order of magnitude as those determined for activated lymphocytes and for cancerous breast cell lines, except for MDA-MB 231 cells. MDA-MB 231 cells bind lactotransferrin with the lowest affinity and, in contrast to other analyzed breast cells, are not recognized by antibodies directed against lymphocyte lactotransferrin receptor. These results suggest that MDA-MB 231 lactotransferrin receptor is different from that characterized at the cell surface of other breast cells. In conclusion, since the lactotransferrin receptor expression was not enhanced at the surface of cancerous cell lines and was not altered by the oncogene transformation of a normal cell (HBL100) to a tumorigenic cell (HH9), the lactotransferrin receptor cannot be considered as a marker of tumor progression.