The mast cell exosome-fibroblast connection: A novel pro-fibrotic pathway.

Introduction: In addition to the traditional activation of resident receptors by release of local mediators, new evidence favors the existence of exosomes in cell-to-cell communication that mediates delivery of specific cargo to modulate recipient cell function. We report that mast cell exosomes are an additional source of pro-fibrotic substances and constitute a unique pathway for the generation of excess collagen. Methods: We use primary human lung fibroblasts (HLFs) to demonstrate the uptake of labeled exosomes isolated from the human mast cell line HMC-1 (MC-EXOs), previously shown to contain protein cargo in common with human mast cell exosomes. Results: The MC-EXO uptake by HLF is to the cytosol and increases both proline hydroxylation in HLF lysate and secreted collagen, within 24 h, which is sustained over 72 h, the same time required for transforming growth factor-ß (TGF-ß) to activate collagen synthesis in the HLFs. Unlike TGF-ß, MC-EXO uptake does not induce fibrillar gene activation or invoke the Smad-nuclear transcription pathway. We show that MC-EXO uptake and TGF-ß have an additive effect on collagen synthesis in HLF and postulate that MC-EXO uptake by HLFs is a contributing factor to excess collagen synthesis and represents a unique paradigm for understanding fibrosis. Discussion: It is known that, in the lungs, mast cells are more activated and increase in number with inflammation, injury and viral infection associated with fibrosis. With the reported increased incidence of post-COVID-pulmonary fibrosis (PCPF), data from patients with severe COVID-19 are presented that show an increase in the mast cell number in lung parenchyma, the site of PCPF. Our findings provide a rationale for targeting multiple fibrogenic pathways in the management of lung fibrosis and the use of mast cell exosomes as a biomarker for the prognostic and diagnostic management of evolving fibrotic lung disease.

Extracellular vesicles from human airway basal cells respond to cigarette smoke extract and affect vascular endothelial cells.

The human airway epithelium lining the bronchial tree contains basal cells that proliferate, differentiate, and communicate with other components of their microenvironment. One method that cells use for intercellular communication involves the secretion of exosomes and other extracellular vesicles (EVs). We isolated exosome-enriched EVs that were produced from an immortalized human airway basal cell line (BCi-NS1.1) and found that their secretion is increased by exposure to cigarette smoke extract, suggesting that this stress stimulates release of EVs which could affect signaling to other cells. We have previously shown that primary human airway basal cells secrete vascular endothelial growth factor A (VEGFA) which can activate MAPK signaling cascades in endothelial cells via VEGF receptor-2 (VEGFR2). Here, we show that exposure of endothelial cells to exosome-enriched airway basal cell EVs promotes the survival of these cells and that this effect also involves VEGFR2 activation and is, at least in part, mediated by VEGFA present in the EVs. These observations demonstrate that EVs are involved in the intercellular signaling between airway basal cells and the endothelium which we previously reported. The downstream signaling pathways involved may be distinct and specific to the EVs, however, as increased phosphorylation of Akt, STAT3, p44/42 MAPK, and p38 MAPK was not seen following exposure of endothelial cells to airway basal cell EVs.

Smoking-Dependent Distal-to-Proximal Repatterning of the Adult Human Small Airway Epithelium.

RATIONALE: Small airways are the primary site of pathologic changes in chronic obstructive pulmonary disease (COPD), the major smoking-induced lung disorder. OBJECTIVES: On the basis of the concept of proximal-distal patterning that determines regional specialization of the airway epithelium during lung development, we hypothesized that a similar program operates in the adult human lung being altered by smoking, leading to decreased regional identity of the small airway epithelium (SAE). METHODS: The proximal and distal airway signatures were identified by comparing the transcriptomes of large and small airway epithelium samples obtained by bronchoscopy from healthy nonsmokers. The expression of these signatures was evaluated in the SAE of healthy smokers and smokers with COPD compared with that of healthy nonsmokers. The capacity of airway basal stem cells (BCs) to maintain region-associated phenotypes was evaluated using the air-liquid interface model. MEASUREMENTS AND MAIN RESULTS: The distal and proximal airway signatures, containing 134 and 233 genes, respectively, were identified. These signatures included known developmental regulators of airway patterning, as well as novel regulators such as epidermal growth factor receptor, which was associated with the proximal airway phenotype. In the SAE of smokers with COPD, there was a dramatic smoking-dependent loss of the regional transcriptome identity with concomitant proximalization. This repatterning phenotype was reproduced by stimulating SAE BCs with epidermal growth factor, which was up-regulated in the SAE of smokers, during differentiation of SAE BCs in vitro. CONCLUSIONS: Smoking-induced global distal-to-proximal reprogramming of the SAE represents a novel pathologic feature of COPD and is mediated by exaggerated epidermal growth factor/epidermal growth factor receptor signaling in SAE BCs.

Endothelial Cell Mediated Promotion of Ciliated Cell Differentiation of Human Airway Basal Cells via Insulin and Insulin-Like Growth Factor 1 Receptor Mediated Signaling.

Human airway basal cells (BC) function as stem/progenitor cells of the human airway epithelium, capable of differentiating into ciliated and secretory cells during turnover and repair. The positioning of BC along the basement membrane allows for potential paracrine signaling from non-epithelial cells in the mesenchyme to regulate BC function. Based on the knowledge that interaction between the airway epithelium and mesenchyme is critical for proper maintenance of both tissues, and that endothelial cells (EC) can regulate multiple functions of BC, the present study was designed to help understand the role of BC and EC cross-talk in regulating BC stem/progenitor function. Using an in vitro co-culture system that mimics the in vivo physical separation of these cell types, we assessed the impact of primary lung microvascular EC on differentiation of primary BC into a mucociliated epithelium. The data demonstrate that co-culture of BC and lung microvasculature EC results in increased ciliated cell differentiation of BC via activation of insulin (INS) and insulin-like growth factor 1 (IGF1) receptor (INSR and IGF1R) mediated signaling in BC. Consistent with this data, siRNA mediated knockdown of INSR and IGF1R in BC suppressed ciliated cell differentiation. Together these findings identify an important signaling pathway required for differentiation of BC into a ciliated cells and demonstrate the importance of BC-EC cross-talk in regulating normal airway epithelial structure.

EGF-Amphiregulin Interplay in Airway Stem/Progenitor Cells Links the Pathogenesis of Smoking-Induced Lesions in the Human Airway Epithelium.

The airway epithelium of cigarette smokers undergoes dramatic remodeling with hyperplasia of basal cells (BC) and mucus-producing cells, squamous metaplasia, altered ciliated cell differentiation and decreased junctional barrier integrity, relevant to chronic obstructive pulmonary disease and lung cancer. In this study, we show that epidermal growth factor receptor (EGFR) ligand amphiregulin (AREG) is induced by smoking in human airway epithelium as a result of epidermal growth factor (EGF)-driven squamous differentiation of airway BC stem/progenitor cells. In turn, AREG induced a unique EGFR activation pattern in human airway BC, distinct from that evoked by EGF, leading to BC- and mucous hyperplasia, altered ciliated cell differentiation and impaired barrier integrity. Further, AREG promoted its own expression and suppressed expression of EGF, establishing an autonomous self-amplifying signaling loop in airway BC relevant for promotion of EGF-independent hyperplastic phenotypes. Thus, EGF-AREG interplay in airway BC stem/progenitor cells is one of the mechanisms that mediates the interconnected pathogenesis of all major smoking-induced lesions in the human airway epithelium. Stem Cells 2017;35:824-837.

JAG1-Mediated Notch Signaling Regulates Secretory Cell Differentiation of the Human Airway Epithelium.

Basal cells (BC) are the stem/progenitor cells of the human airway epithelium capable of differentiating into secretory and ciliated cells. Notch signaling activation increases BC differentiation into secretory cells, but the role of individual Notch ligands in regulating this process in the human airway epithelium is largely unknown. The objective of this study was to define the role of the Notch ligand JAG1 in regulating human BC differentiation. JAG1 over-expression in BC increased secretory cell differentiation, with no effect on ciliated cell differentiation. Conversely, knockdown of JAG1 decreased expression of secretory cell genes. These data demonstrate JAG1-mediated Notch signaling regulates differentiation of BC into secretory cells.

Endothelial MMP14 is required for endothelial-dependent growth support of human airway basal cells.

Human airway basal cells are the stem (or progenitor) population of the airway epithelium, and play a central role in anchoring the epithelium to the basement membrane. The anatomic position of basal cells allows for potential paracrine signaling between them and the underlying non-epithelial stromal cells. In support of this, we have previously demonstrated that endothelial cells support growth of basal cells during co-culture through vascular endothelial growth factor A (VEGFA)-mediated signaling. Building on these findings, we found, by RNA sequencing analysis, that basal cells expressed multiple fibroblast growth factor (FGF) ligands (FGF2, FGF5, FGF11 and FGF13) and that only FGF2 and FGF5 were capable of functioning in a paracrine manner to activate classical FGF receptor (FGFR) signaling. Antibody-mediated blocking of FGFR1 during basal-cell-endothelial-cell co-culture significantly reduced the endothelial-cell-dependent basal cell growth. Stimulation of endothelial cells with basal-cell-derived growth factors induced endothelial cell expression of matrix metallopeptidase 14 (MMP14), and short hairpin RNA (shRNA)-mediated knockdown of endothelial cell MMP14 significantly reduced the endothelial-cell-dependent growth of basal cells. Overall, these data characterize a new growth-factor-mediated reciprocal 'crosstalk' between human airway basal cells and endothelial cells that regulates proliferation of basal cells.

Activation of NOTCH1 or NOTCH3 signaling skews human airway basal cell differentiation toward a secretory pathway.

Airway basal cells (BC) function as stem/progenitor cells capable of differentiating into the luminal ciliated and secretory cells to replenish the airway epithelium during physiological turnover and repair. The objective of this study was to define the role of Notch signaling in regulating human airway BC differentiation into a pseudostratified mucociliated epithelium. Notch inhibition with γ-secretase inhibitors demonstrated Notch activation is essential for BC differentiation into secretory and ciliated cells, but more so for the secretory lineage. Sustained cell autonomous ligand independent Notch activation via lentivirus expression of the intracellular domain of each Notch receptor (NICD1-4) demonstrated that the NOTCH2 and 4 pathways have little effect on BC differentiation into secretory and ciliated cells, while activation of the NOTCH1 or 3 pathways has a major influence, with persistent expression of NICD1 or 3 resulting in a skewing toward secretory cell differentiation with a parallel decrease in ciliated cell differentiation. These observations provide insights into the control of the balance of BC differentiation into the secretory vs ciliated cell lineage, a balance that is critical for maintaining the normal function of the airway epithelium in barrier defense against the inhaled environment.

Generation of a human airway epithelium derived basal cell line with multipotent differentiation capacity.

BACKGROUND: As the multipotent progenitor population of the airway epithelium, human airway basal cells (BC) replenish the specialized differentiated cell populations of the mucociliated airway epithelium during physiological turnover and repair. Cultured primary BC divide a limited number of times before entering a state of replicative senescence, preventing the establishment of long-term replicating cultures of airway BC that maintain their original phenotype. METHODS: To generate an immortalized human airway BC cell line, primary human airway BC obtained by brushing the airway epithelium of healthy nonsmokers were infected with a retrovirus expressing human telomerase (hTERT). The resulting immortalized cell line was then characterized under non-differentiating and differentiating air-liquid interface (ALI) culture conditions using ELISA, TaqMan quantitative PCR, Western analysis, and immunofluorescent and immunohistochemical staining analysis for cell type specific markers. In addition, the ability of the cell line to respond to environmental stimuli under differentiating ALI culture was assessed. RESULTS: We successfully generated an immortalized human airway BC cell line termed BCi-NS1 via expression of hTERT. A single cell derived clone from the parental BCi-NS1 cells, BCi-NS1.1, retains characteristics of the original primary cells for over 40 passages and demonstrates a multipotent differentiation capacity into secretory (MUC5AC, MUC5B), goblet (TFF3), Clara (CC10) and ciliated (DNAI1, FOXJ1) cells on ALI culture. The cells can respond to external stimuli such as IL-13, resulting in alteration of the normal differentiation process. CONCLUSION: Development of immortalized human airway BC that retain multipotent differentiation capacity over long-term culture should be useful in understanding the biology of BC, the response of BC to environmental stress, and as a target for assessment of pharmacologic agents.

Reduction of virulence factor pyocyanin production in multidrug-resistant Pseudomonas aeruginosa.

Nosocomial infections caused by metallo-ß-lactamase (MBL)-producing multidrug-resistant (MDR) Pseudomonas aeruginosa have become a worldwide problem. Pyocyanin, a representative pigment produced by P. aeruginosa, is the major virulence factor of this organismThe aim of this study was to investigate the pyocyanin-producing ability of MBL-producing MDR P. aeruginosa. A total of 50 clinical isolates of P. aeruginosa, including 20 MDR strains, were collected at 18 general hospitals in Japan. The chromaticity and luminosity produced by pyocyanin in each isolate were measured. The quantity of pyocyanin and the expression of the phzM and phzS genes coding a pyocyanin synthesis enzyme were measured. MDR strains showed a bright yellow-green, while non-MDR strains tended to show a dark blue-green. The quantities of pyocyanin in MBL-producing strains and non-producing strains were 0.015 ± 0.002 and 0.41 ± 0.10 µg, respectively. The expression of the phzM and phzS genes in the MDR strains was 11 and 14 %, respectively, of the expression in the non-MDR strains. When the MBL gene was transduced into P. aeruginosa and it acquired multidrug resistance, it was shown that the pyocyanin-producing ability decreased. The pathogenicity of MBL-producing MDR P. aeruginosa may be lower than that of non-MDR strains. These MBL-producing MDR strains may be less pathogenic than non-MDR strains. This may explain why MDR-P. aeruginosa is unlikely to cause infection but, rather, causes subclinical colonization only.

Usefulness of linezolid in the treatment of hospital-acquired pneumonia caused by MRSA: a prospective observational study.

Clinical results for linezolid (LZD) treatment of hospital-acquired pneumonia (HAP) caused by methicillin-resistant Staphylococcus aureus (MRSA), particularly microbiologically evaluable or severe cases, are limited in Japan. A prospective observational study was conducted in order to assess the usefulness of LZD in Japanese patients with MRSA pneumonia. The study tracked fifteen participants treated with LZD for pneumonia who met the criteria of the HAP guidelines and were confirmed to have pneumonia caused by MRSA. Of these, six were severe and 13 had received antibiotic treatment before treatment with LZD. Of the 13 participants assessed for their clinical responses, seven were rated as cures, three were rated as failures, and three were indeterminate. The overall cure rate (cure/cure + failure) was 70.0% (7/10), and the cure rate by severity was 33.3% (1/3) for severe cases and 85.5% (6/7) for moderate cases. The one severe case with a clinical response rating of cure had failed to respond to vancomycin. Among the seven participants with a clinical response rating of cure, the microbiological response was eradication in three, presumed eradication in three, and indeterminate in one. Three serious adverse events occurred in two of the 15 participants, but none were considered to be causally related to LZD. The results suggest that LZD has high potential for severe and multidrug-resistant cases. A higher cure rate was achieved in moderate cases. In cases of pneumonia that are most likely MRSA infections with poor prognosis, it was suggested to be important for patient outcome to implement the most effective therapy before the patient's condition becomes serious.

Antibacterial activity of carbapenems against clinical isolates of respiratory bacterial pathogens in the northeastern region of Japan in 2007.

As the increasing prevalence of resistant strains of respiratory bacterial pathogens has recently been reported, continuous monitoring of the susceptibility of clinical isolates to antibacterial agents is important. We performed a surveillance study focusing on the susceptibility of major respiratory bacterial pathogens in the northeastern region of Japan to carbapenems and control drugs. A total of 168 bacterial strains isolated from patients with respiratory tract infections in 2007 were collected and the minimum inhibitory concentration (MIC) determined. MIC data were subjected to pharmacokinetic/pharmacodynamic analysis with Monte Carlo simulation to calculate the probability of achieving the target of time above MIC with each carbapenem. All Moraxella catarrhalis, Streptococcus pneumoniae, and methicillin-sensitive Staphylococcus aureus isolates were susceptible to carbapenems. Despite the increasing prevalence of ß-lactamase-nonproducing ampicillin-resistant strains, all Haemophilus influenzae isolates were susceptible to meropenem. For Pseudomonas aeruginosa, the susceptibility rates for meropenem and biapenem were 76.7%, and the highest probability of achieving pharmacodynamic target (40% of the time above MIC) was obtained with meropenem 0.5 g three times daily as a 4-h infusion (89.4%), followed by meropenem 0.5 g four times daily as a 1-h infusion (88.4%). Carbapenems have retained their position as key drugs for severe respiratory tract infections.

Antibacterial effects of brand-name teicoplanin and generic products against clinical isolates of methicillin-resistant Staphylococcus aureus.

Glycopeptide antibiotics, such as vancomycin and teicoplanin, have been used worldwide to treat infection caused by methicillin-resistant Staphylococcus aureus (MRSA). Generic teicoplanin products were manufactured by many companies in 2009. We investigated the susceptibility of 147 MRSA strains to brand-name teicoplanin (TEIC-1) and seven generic products (TEIC-2 to TEIC-8). The MIC(90) of generic TEIC-5 and TEIC-7 was 8 µg/ml whereas that of TEIC-1 and other generic products was 4 µg/ml. The potency equivalent of generic TEIC-5 and TEIC-7 was lower than that of TEIC-1, and TEIC content (%) per potency equivalent (200 mg) in a vial of these two generic products varied greatly compared with the other products. Although the potency equivalent of the TEIC used in this study was within the range stipulated in the Japanese Pharmacopeia, these results showed that the potency equivalent and susceptibility of two of the seven generic products differed from that of TEIC-1. The predicted AUC(0-72) value of those two generic products was 84-85% in comparison with that of TEIC-1. Among generic drugs, there may be products whose antimicrobial effect is not equal to that of the brand teicoplanin.

Efficacy of clarithromycin plus vancomycin in mice with implant-related infection caused by biofilm-forming Staphylococcus aureus.

BACKGROUND: Staphylococcal biofilms pose an important problem, especially after orthopedic surgery using foreign implants. Clarithromycin (CAM) eliminates the biofilms formed by a wide variety of aerobic and anaerobic bacteria. In a previous in vitro study, we showed that treatment with CAM and vancomycin (VCM) eradicated staphylococcal biofilms from surgical implants. To investigate the efficacy of this eradication therapy, we assessed its effects against Staphylococcus aureus on titanium plates implanted in mice. METHODS: A titanium washer covered with S. aureus biofilms was implanted in the muscular tissue around the femoral bone. Mice were given intravenous injections of CAM and intraperitoneal injections of VCM twice daily beginning 72 h after implantation. To confirm eradication of biofilms and S. aureus strains, the resected washer was examined by scanning electron microscopy. RESULTS: Dense colonization and biofilms were seen on the washer implanted in the control mice that received saline, saline plus CAM, or saline plus VCM. Treatment with CAM plus VCM eliminated the biofilms, indicating an S. aureus eradication effect. CONCLUSIONS: Staphylococcal biofilms have demonstrated resistance to most antibiotics, including VCM. Our in vivo data support the hypothesis that combined treatment using CAM plus VCM may effectively eradicate staphylococcal biofilms in patients with implant-related infection.

Randomized phase II trial comparing amrubicin with topotecan in patients with previously treated small-cell lung cancer: North Japan Lung Cancer Study Group Trial 0402.

PURPOSE: Amrubicin, a new anthracycline agent, and topotecan are both active for previously treated small-cell lung cancer (SCLC). No comparative study of these agents has been reported. This randomized phase II study was conducted to select amrubicin or topotecan for future evaluation. PATIENTS AND METHODS: Patients with SCLC previously treated with platinum-containing chemotherapy were randomly assigned to receive amrubicin (40 mg/m(2) on days 1 through 3) or topotecan (1.0 mg/m(2) on days 1 through 5). Patients were stratified by Eastern Cooperative Oncology Group performance status (0, 1, or 2) and type of relapse (chemotherapy sensitive or refractory). The primary end point was overall response rate (ORR), and secondary end points were progression-free survival (PFS), overall survival, and toxicity profile. RESULTS: From February 2004 to July 2007, 60 patients were enrolled, and 59 patients (36 patients with sensitive and 23 patients with refractory relapse) were assessable for efficacy and safety evaluation. Neutropenia was severe, and one treatment-related death owing to infection was observed in the amrubicin arm. ORRs were 38% (95% CI, 20% to 56%) for the amrubicin arm and 13% (95% CI, 1% to 25%) for the topotecan arm. In sensitive relapse, ORRs were 53% for the amrubicin arm and 21% for the topotecan arm. In refractory relapse, ORRs were 17% for the amrubicin arm and 0% for the topotecan arm. Median PFS was 3.5 months for patients in the amrubicin arm and 2.2 months for patients in the topotecan arm. Multivariate analysis revealed that amrubicin has more influence than topotecan on overall survival. CONCLUSION: Amrubicin may be superior to topotecan with acceptable toxicity for previously treated patients with SCLC. Further evaluation of amrubicin for relapsed SCLC is warranted.

Combined efficacy of clarithromycin plus cefazolin or vancomycin against Staphylococcus aureus biofilms formed on titanium medical devices.

In this study, we investigated the in vitro efficacy of clarithromycin (CLA) combined with cefazolin (CFZ) or vancomycin (VCM) against Staphylococcus aureus biofilms formed on titanium devices in order to confirm the efficacy of eradication therapies against device-related infection. The distribution of CLA in muscle tissue surrounding bone was also investigated by liquid chromatography/tandem mass spectrometry in 10 orthopaedic patients. Biofilm formation and eradication of S. aureus were monitored by scanning electron microscopy and using double-staining dyes, respectively. Although S. aureus biofilms were not eradicated by CLA, CFZ or VCM alone, CLA combined with CFZ or VCM destroyed biofilms, and S. aureus eradication was clearly observed 72 h later. This in vitro study showed that treatment with CLA plus CFZ or VCM destroyed staphylococcal biofilms formed on medical devices and eradicated S. aureus.

Adenocarcinoma with epidermal growth factor receptor gene mutations in three siblings.

Sensitivity to an inhibitor of epidermal growth factor receptor (EGFR) kinase strongly correlates with EGFR somatic mutations in non-small cell lung cancer. These mutations are frequently found in patients with adenocarcinoma, never- or light-smokers, women, and East Asians. In this study, we show an aggregation of three non-small cell lung cancer cases with EGFR gene mutations in one family. The subjects were all female, never- or light-smokers with adenocarcinoma. Two of the patients responded to treatment with gefitinib. A genetic study of these cases would be useful in elucidating genetic susceptibility to lung cancer in persons with EGFR mutations.