Porcine sinus mucosa holds cells that respond to bone morphogenetic protein (BMP)-6 and BMP-7 with increased osteogenic differentiation in vitro

The aim of this in vitro study was to determine whether the sinus mucosa holds cells with an osteogenic potential. Frozen sections of sinus mucosa from three adult pigs were investigated for the expression of STRO-1, a marker of mesenchymal progenitor cells, and alkaline phosphatase activity, an enzyme expressed by cells committed to the osteogenic lineage and by mature osteoblasts. To determine their osteogenic potential, mucosa-derived cells were incubated with bone morphogenetic protein (BMP)-6 and BMP-7, and alkaline phosphatase activity, osteocalcin expression, and mineralization of the extracellular matrix was measured. We found sinus mucosa cells staining positive for STRO-1 and alkaline phosphatase activity. When sinus mucosa tissue was placed in culture, alkaline phosphatase positive cells grew out from the explants and further increased alkaline phosphatase activity in response to BMP-6 and BMP-7. The expression level of the osteoblast-specific extracellular matrix protein osteocalcin, and the amount of calcium accumulation within the extracellular matrix was also increased in response to BMPs. We conclude that the sinus mucosa holds mesenchymal progenitor cells and cells committed to the osteogenic lineage that can respond to BMP-6 and BMP-7 by an increase of their osteogenic differentiation.

The cigarette smoke component acrolein inhibits expression of the innate immune components IL-8 and human beta-defensin 2 by sinonasal epithelial cells

BACKGROUND

Tobacco use is associated with poorer outcomes of medical and surgical therapy for chronic rhinosinusitis (CRS), although the underlying mechanism is unknown. Acrolein (AC) is a major component of cigarette smoke that has been shown to suppress innate immune gene expression by human bronchial epithelial cells and murine macrophages. In this study, we explore whether exposure of human sinonasal epithelial cells (HSNECs) to AC similarly reduces their innate immune gene expression.

METHODS

Primary HSNECs from CRS patients were grown in culture, either differentiated or submerged. HSNECs were treated for 30 minutes with 0-50 microM of AC and were subsequently analyzed by real-time polymerase chain reaction and ELISA to determine IL-8 and human beta-defensin (HBD) 2 expression. Total glutathione was measured to see the oxidative stress within the treatment range.

RESULTS

In primary HSNEC, IL-8 mRNA levels decreased dose dependently in the range of 10-50 microM of AC with an eightfold decrease at 50 microM. In addition, a 125-fold decrease at 50 microM for IL-8 protein was observed. HBD-2 mRNA decreased twofold and HBD-2 protein decreased fourfold at 50 microM of AC in primary HSNEC. However, differentiated HSNEC showed a marginal decrease in a dose-dependent manner for both IL-8 and HBD-2 within the range of 10-50 microM of AC. There was no oxidative stress observed over this range of AC concentration.

CONCLUSION

The tobacco smoke component AC has the capacity to suppress the inflammatory and innate immune function of sinonasal epithelial cells. Whether this effect contributes to the negative clinical impact of smoking on CRS outcomes merits additional investigation.

Cell division rates decrease with age, providing a potential explanation for the age-dependent deceleration in cancer incidence

A new evaluation of previously published data suggested to us that the accumulation of mutations might slow, rather than increase, as individuals age. To explain this unexpected finding, we hypothesized that normal stem cell division rates might decrease as we age. To test this hypothesis, we evaluated cell division rates in the epithelium of human colonic, duodenal, esophageal, and posterior ethmoid sinonasal tissues. In all 4 tissues, there was a significant decrease in cell division rates with age. In contrast, cell division rates did not decrease in the colon of aged mice, and only small decreases were observed in their small intestine or esophagus. These results have important implications for understanding the relationship between normal stem cells, aging, and cancer. Moreover, they provide a plausible explanation for the enigmatic age-dependent deceleration in cancer incidence in very old humans but not in mice.

Nasal anatomy, physiology, and function

The nose in man, despite its unusual external appearance, has a variety of functions that are related to its unique internal anatomy and the vascular tone of its mucous membrane. In addition, it houses the receptor side of the first cranial nerve. This receptor is relatively primitive in man and probably less effective in monitoring his environment than that of other mammals. The nose is the portal by which the ambient air first enters the body. The nose functions as a "guard dog" or "watch dog" for the lungs. It conditions air to a specific range of temperature and humidity. Its protective filtration and ciliary mechanisms are abundant. Nasal reflex functions affect the lower respiratory tract and cardiopulmonary functions and respond to intense emotional situations. Since the time of Proetz' original essays on the physiology of the nose, a great deal of study has been done on the various and myriad functions of the nose. A working understanding of its peculiar anatomy and unusual functions are important for understanding the pathophysiology of nasal disease.

Bacterial products increase expression of the human cathelicidin hCAP-18/LL-37 in cultured human sinus epithelial cells

The respiratory epithelium plays a major role in the primary defense of the airways against infection. It has been demonstrated that bacterial products are involved in the induction of inflammatory reactions of the upper airways. Little is known about the effects of bacterial products on expression of the antimicrobial peptide hCAP-18/LL-37, the only human cathelicidin identified so far. The aim of this study was to investigate the effects of bacterial products from both gram-positive and gram-negative bacteria on the expression of hCAP-18/LL-37 by sinus epithelial cells using an air-exposed tissue culture model. Lipopolysaccharide and lipoteichoic acid both increased hCAP-18/LL-37 expression in cultured sinus epithelium as assessed by immunohistochemistry, where maximal stimulation occurred at 100 ng ml(-1) lipopolysaccharide or 10 microg ml(-1) lipoteichoic acid. The stimulatory effect of lipopolysaccharide and lipoteichoic acid was not restricted to expression of hCAP-18/LL-37, since also mucin expression and IL-8 release from cultured sinus epithelium cells were increased by lipopolysaccharide and lipoteichoic acid. This suggests that bacterial products may stimulate innate immunity in the upper airways.

Eosinophil production of prostaglandin D2 in patients with aspirin-exacerbated respiratory disease

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) differs from aspirin-tolerant disease in part because of eosinophilic tissue infiltration and overexpression of arachidonic acid metabolic pathway components that lead to enhanced secretion of cysteinyl leukotrienes and prostaglandin (PG) D₂ observed constitutively and paradoxically in response to aspirin and other COX inhibitors. We have previously demonstrated the capacity of IFN-γ to drive cysteinyl leukotriene expression and response.

OBJECTIVE

We investigated eosinophils as a source of PGD₂ production in patients with AERD.

METHODS

Eosinophils were enriched from tissue and peripheral blood obtained from control subjects, patients with aspirin-tolerant disease, and patients with AERD. mRNA was extracted and evaluated for expression of hematopoietic prostaglandin D synthase (hPGDS). Expression of hPGDS protein was confirmed with Western hybridization and immunofluorescence staining. Cells were stimulated with aspirin, and secretion of PGD₂ was quantified. CD34⁺ progenitor cells were isolated and matured into eosinophils in the presence or absence of IFN-γ and hPGDS mRNA, and PGD₂ release was measured.

RESULTS

Gene expression analysis revealed that eosinophils from tissue and blood of patients with AERD display increased levels of hPGDS compared with asthmatic and control samples. Western hybridization confirmed the increase in hPGDS mRNA translated to increased protein expression. Immunofluorescence confirmed mast cells and eosinophils from tissue of patients with AERD and asthma demonstrated hPGDS expression, with higher levels in eosinophils from patients with AERD. Incubation of eosinophils from blood and tissue with aspirin stimulated PGD₂ release. IFN-γ-matured eosinophil progenitors showed enhanced hPGDS expression and increased levels of PGD₂ release at baseline and after aspirin stimulation.

CONCLUSIONS

In addition to mast cells, eosinophils represent an important source of PGD₂ in patients with AERD and identify a new target for therapeutic intervention.

A comparison of experimental methods in molecular chronic rhinosinusitis research

BACKGROUND

Research into the molecular pathogenesis of chronic rhinosinusitis (CRS) requires the collection and analysis of sinonasal tissue. Recent gene expression studies have used either surgical tissue specimens or isolated epithelial cell preparations. Here, we compare cultures of nasal epithelial cells, nasal brush biopsy, and whole ethmoid mucosa with respect to expression of innate immune genes.

METHODS

Ethmoid mucosa was collected intraoperatively from 12 CRS and control patients. This tissue either was processed whole for mRNA extraction or was used to generate primary nasal epithelial cell cultures. After 6 weeks, epithelial cells in culture were assessed for multiple innate immune proteins by flow cytometry. In parallel, middle meatal brush biopsy specimens were obtained from the same patients and studied acutely in a similar fashion by flow cytometry. Expression of innate immune genes was determined in whole tissue samples by real-time polymerase chain reaction.

RESULTS

Flow cytometry revealed that brush biopsy specimens contain 75% epithelial cells, whereas primary nasal epithelial cell cultures were pure. Epithelial cells derived from individual subjects expressed very similar levels of innate immune markers whether studied acutely or after 6 weeks in culture. Whole tissue mRNA levels were variable and not correlated to epithelial expression.

CONCLUSION

The choice of experimental methodology can greatly influence the results and interpretation of CRS research. Primary nasal epithelial cells maintain their innate immune receptor expression profile when grown in prolonged culture in vitro. These findings imply that alterations in innate immune gene expression in CRS may be intrinsic to the epithelial cells, even outside of their in vivo microenvironment.

Plant flavones enhance antimicrobial activity of respiratory epithelial cell secretions against Pseudomonas aeruginosa

Flavones are a class of natural plant secondary metabolites that have anti-inflammatory and anti-bacterial effects. Some flavones also activate the T2R14 bitter taste receptor, which is expressed in motile cilia of the sinonasal epithelium and activates innate immune nitric oxide (NO) production. Flavones may thus be potential therapeutics for respiratory infections. Our objective was to examine the anti-microbial effects of flavones on the common sinonasal pathogens Candida albicans, Staphylococcus aureus, and Pseudomonas aeruginosa, evaluating both planktonic and biofilm growth. Flavones had only very low-level antibacterial activity alone. They did not reduce biofilm formation, but did reduce production of the important P. aeruginosa inflammatory mediator and ciliotoxin pyocyanin. However, flavones exhibited synergy against P. aeruginosa in the presence of antibiotics or recombinant human lysozyme. They also enhanced the efficacy of antimicrobials secreted by cultured and primary human airway cells grown at air-liquid interface. This suggests that flavones may have anti-gram-negative potential as topical therapeutics when combined with antibiotics or in the context of innate antimicrobials secreted by the respiratory or other epithelia. This may have an additive effect when combined with T2R14-activated NO production. Additional studies are necessary to understand which flavone compounds or mixtures are the most efficacious.

Comparison of chloroform-induced toxicity in the kidneys, liver, and nasal passages of male Osborne-Mendel and F-344 rats

Chloroform given by gavage in corn oil at 180 mg/kg per day induced kidney tumors in male Osborne-Mendel rats. Chloroform-induced cytotoxicity and regenerative cell proliferation have been observed in the kidneys of male F-344 rats. In order to compare the acute sensitivity of male Osborne-Mendel with F-344 rats, animals from both strains were administered a single gavage dose of 0, 10, 34, 90, 180, or 477 mg/kg chloroform and necropsied 48 h later. Known target tissues were examined for histological changes. Regenerative cell proliferation was assessed as a labeling index (LI, percent of cells in S-phase) as determined by nuclear incorporation of bromodeoxyuridine. The epithelial cells of the proximal tubules of the kidney cortex were the primary target cells for cytotoxicity and regenerative cell proliferation. A dose-dependent increase in the LI was present in the kidney of Osborne-Mendel rats given doses of 10 mg/kg chloroform and above and in F-344 rats given 90 mg/kg and above. The maximal increase in the LI was 4.5- or 3.7-fold over control in Osborne-Mendel or F-344 given 477 mg/kg, respectively. The only increase in the hepatocyte LI was in the F-344 rats given 477 mg/kg. Edema and periosteal hypercellularity were observed in the nasal passages of both strains at doses of 90 mg/kg and above. These data indicate that Osborne-Mendel and F-344 rats are about equally susceptible to chloroform-induced nephrotoxicity. These results provide a basis for linking the extensive data base on mechanisms of action of chloroform toxicity in F-344 rats to the Osborne-Mendel rat and support the hypothesis that events secondary to chloroform-induced cytolethality and regenerative cell proliferation played a role in the induction of renal tumors in the Osborne-Mendel rat.

The early development of sino-nasal mucosa

The development of human nasal mucosa was studied in 20 fetal heads between 8 and 24 weeks of gestation. Initially the nasal cavity is lined by a single layer of flattened cells, which produces two to three layers of undifferentiated spherical cells. Olfactory epithelium lines the cranial portion of the human fetal nasal cavity at 8 weeks of gestation. Pseudostratified ciliated cuboidal or columnar epithelium appears at 9 weeks of gestation in the nasal cavity and between 14 and 16 weeks of gestation in the primitive ethmoid sinuses and maxillary sinus infundibulum. Goblet cells and glandular acini appear between 12 and 14 weeks of gestation. Initially these goblet cells/glands are found predominantly in the anterior nasal cavity but are more evenly distributed at 24 weeks of gestation. The epithelial development of the nasal septum generally precedes that of the lateral nasal wall. This study documents nasal mucosal maturation and associated anatomic development in the human fetus.

Impact of tobacco smoke on upper airway dendritic cell accumulation and regulation by sinonasal epithelial cells

BACKGROUND

In these studies we examined the impact of environmental tobacco smoke (ETS) and active smoking on sinonasal dendritic cell (DC) subsets in controls or patients with chronic rhinosinusitis with nasal polyps (CRSwNP). In subsequent in-vitro investigations, we examined the influence of cigarette smoke extract (CSE) on human sinonasal epithelial cells' (HSNECs) ability to regulate DC functions.

METHODS

Sinonasal tissue, blood, and hair were collected from patients undergoing sinus surgery. Smoking status and ETS exposure were determined by hair nicotine. DC subsets were examined by flow cytometric analysis. Monocyte-derived dendritic cells (moDCs) were treated with conditioned medium from non-smoked-exposed HSNECs (NS-HSNECs) or cigarette-smoke-extract-exposed HSNECs (CSE-HSNECs) to assess the impact of CSE exposure on HSNEC regulation of moDC functions.

RESULTS

Control subjects who were active smokers displayed increased sinonasal moDC and myeloid dendritic 1 (mDC1) cells and reduced mDC2 cells, whereas, in CRSwNP patients, only moDC and mDC2 cells were altered. ETS was found to increase only moDCs in the CRSwNP patients. In vitro, CSE stimulated HSNEC secretion of the moDC regulatory products chemokine (C-C motif) ligand 20, prostaglandin E2 , and granulocyte-macrophage colony-stimulating factor. CSE exposure also promoted HSNECs to stimulate monocyte and moDC migration. moDCs treated with CSE-HSNEC media stimulated an increase in antigen uptake and expression of CD80 and CD86. Last, CSE-HSNEC-treated moDCs secreted increased levels of interleukin-10, interferon-γ, and thymic stromal lymphopoietin.

CONCLUSION

Active smoking, and to a lesser degree ETS, alters the sinonasal composition of DCs. A potential mechanism to account for this is that cigarette smoke stimulates HSNECs to induce moDC migration, maturation, and activation.

Generation of thromboxane A2 from highly purified human sinus mast cells after immunological stimulation

To better understand metabolites of arachidonic acid generated from human mast cells, the present study assessed the capacity of human mast cells to synthesize thromboxane B2 (TXB2). Anti-IgE challenge of human sinus mast cells resulted in the generation of TXB2 in a dose-dependent manner with a maximal generation of 8.2+/-4.4 ng/10(6) cells (n = 12), which is about 10-fold lower than the maximal generation of prostaglandin D2 (PGD2). Pretreatment of the cells with OKY-046, an inhibitor of TXA synthase, prevented formation of TXB2 in a dose-dependent manner without affecting the generation of PGD2 or leukotriene C4. Experiments using indomethacin or MK-591, a potent FLAP inhibitor, showed that shunting of arachidonic acid did not occur in a single-cell suspension of mast cells. Analysis by RT-PCR revealed that two species of TXA synthase, the full-length TXA synthase mRNA (TXAS-1, 570 BP) and a small quantity of the alternate-spliced form (400 BP), were present in mast cells. When cellular levels of TXAS-1 mRNA were normalized to those of G3PDH mRNA, the relative concentration of TXAS-1 was 2.06+/-0.60 (n = 7) in highly purified sinus mast cells (92.3+/-3.0% pure) and 3.66+/-0.98 (n = 5) in eosinophils.

Staphylococcus aureus adherence to nasal epithelial cells in a physiological in vitro model

Nasal carriage of Staphylococcus aureus represents a risk factor for subsequent invasive infections and interpatient transmission of strains. No physiological in vitro model of nasal epithelial cells is available to study both patient- and bacteria-related characteristics and their interaction, leading to adherence and colonization. Starting with tissues from human nasal polyps, a confluent, squamous, nonkeratinized epithelium in collagen-coated 96-well microtiter plates was obtained after 14 d. This in vitro cell-layer was characterized histologically, ultrastructurally, and immunohistochemically and showed features that were indistinguishable from those observed in the squamous nonkeratinized epithelium found in the posterior part of the vestibulum nasi. Adherence experiments were performed with four different 3H-thymidine-labeled Staphylococcus aureus strains. The effect of bacterial inoculum size, temperature of incubation, and incubation medium were studied. The adherence results were found to be reproducible, reliable and sensitive, allowing detection of small quantitative differences in adherence between the Staphylococcus aureus strains. There was no significant difference in adherence at 23 degrees C and 37 degrees C, nor between the incubation medium M199 and phosphate-buffered saline. Plastic adherence could be reduced and standardized with use of siliconized tips and a constant bacterial inoculum volume of 100 microl/well. This physiological and reliable in vitro cell-culture model offers a unique opportunity to study Staphylococcus aureus adherence to squamous, nonkeratinized nasal epithelial cells and both patient and bacterial characteristics involved in this interaction.

Mucus production in the nasal sinuses

The density of goblet cells and glands was determined in the maxillary, ethmoidal, frontal, and sphenoidal sinuses. Goblet cells showed the highest density in the maxillary sinuses. 9700 per mm2, while in the other sinuses their density was approximately the same, from 5 900 to 6 500 cell per mm2. The density of glands was highest in the ethmoids, 0.5 gland/mm2, then in the maxillary sinuses, viz. 0.2 gland/mm2, while in the frontal and sphenoidal sinuses it was very low, 0.08 and 0.06 gland/mm2 respectively.

Further characterization of dispersed human sinus mast cells

We have examined biochemical and functional characteristics of dispersed sinus mast cells and compared them with those of mast cells dispersed from other tissues. This experiment yielded the following results. 1) Although no difference was observed in histamine content, tryptase content in sinus mast cells was significantly lower than that of skin and lung mast cells. 2) In contrast with the situation in foreskin mast cells, anti-IgE-induced histamine release from sinus and lung mast cells was potentiated with lower concentrations of adenosine. 3) Similar to lung mast cells, sinus mast cells did not respond to compound 48/80 or substance P, whereas skin mast cells were stimulated to release histamine with either 10 micrograms/ml of compound 48/80 (14.0%) or 10(-4) M of substance P (23.4%). 4) Sinus mast cells are similar to lung mast cells in terms of release of arachidonic acid metabolites. Anti-IgE challenge of sinus mast cells caused the generation of both prostaglandin D2 (89.5 +/- 33.7 ng/10(6) mast cells, n = 14) and i-leukotriene D4 (78.7 +/- 46.8 ng/10(6) mast cells, n = 10).

Airway reconstruction with carrier-free cell sheets composed of autologous nasal squamous epithelium

OBJECTIVES/HYPOTHESIS

Although skin has been the most effective graft material for reconstructing the airway lumen, the use of squamous epithelium has many problems. If autologous airway squamous epithelium could differentiate into mucociliary epithelium after in vivo grafting, it could be an answer to these problems. In this study, we wanted to examine whether carrier-free nasal epithelial cell sheets composed of autologous squamous epithelium could be used as a substitute for skin in airway luminal reconstruction in three maxillectomy patients.

STUDY DESIGN

In vitro biochemical experiments with in vivo applications.

METHODS

We cultured nasal squamous epithelium from three maxillary cancer patients prior to maxillectomy. These squamous cell sheets were grafted on the forearm free flap, and, after maxillectomy, the surgical defect was reconstructed with a prefabricated myocutaneous radial forearm free flap with the cultured nasal squamous epithelium. At 1 and 3 month intervals after the reconstructive surgery, the cultured cell grafted area was investigated with histologic phenotype, comparing the skin grafted area.

RESULTS

The autologous nasal squamous epithelial cell sheet differentiated into mucociliary epithelium without the crust or mucus stagnation that is usually observed in cases in which skin graft is used for airway reconstruction.

CONCLUSIONS

We suggest that autologous cultured nasal squamous epithelium, which differentiates into mucociliary epithelium after in vivo grafting, can be used as a clinically relevant substitute for skin graft in airway luminal reconstruction.

Factors influencing the goblet cell density in paranasal sinuses

The goblet cell density in normal and abnormal paranasal sinuses is presented and compared with other areas of the respiratory tract. Several factors influencing the goblet cell density are discussed.

Quantitative histology of the mucous membrane of the accessory nasal sinus and mastoid cavities

The mucous membranes of the accessory nasal sinuses and of the mastoid labyrinth were measured in undecalcified, plastic-embedded specimens from nonpathologic postmortem cases. Epithelial thicknesses, lamina propria thicknesses and the ratio of nuclear to total cell area of the epithelia are presented for these organs to provide a quantitative basis for dosimetric calculations of alpha-emitting radionuclides. These data will be of value for studies in populations at risk for head carcinomas from the intake of radium and related nuclides.

Fibrinolytic activity in medium from tissue culture of paranasal mucous membrane

It is known that a remarkable fibrinolytic activity of plasminogen activator (PA) can be seen in extracts of wet tissue and acetone powder preparation of paranasal mucous membrane evidencing chronic sinusitis. However, the origin of the PA in extract of paranasal mucous membrane has not yet been clarified up to the present time. In this experiment, using a tissue culture of paranasal mucous membrane, it was observed that two species of cells, epithelial cells and fibrocytes, proliferated in the implanted tissue. PA was isolated from the conditioned medium on the fifth day after culture. From these results, it appears that the PA may be released from epithelial cells and/or fibroblasts.

Density of epithelial cells in the normal human nose and the paranasal sinus mucosa. A scanning electron microscopic study

214 biopsies of mucosa from various sites of the nose and paranasal sinuses were obtained post-mortem and examined using the scanning electron microscope. The density of ciliated cells was increased in the nasal cavity, in the antero-posterior direction. In paranasal sinuses the density of these cells was high, except near the ostium of the maxillary sinus, where the density was decreased by half. Non-ciliated epithelial cells were found in relatively few areas: anterior aspect of the middle and lower turbinates, anterior septum. However, no uniform distribution of these cells was present. The density of goblet cells was significantly lower in the paranasal sinuses as compared to the nasal cavity, with the highest density being found near the ostium of the maxillary sinus.