Accumulation of CD69+ tissue‑resident memory T cells in the nasal polyps of patients with chronic rhinosinusitis

In patients with chronic rhinosinusitis with nasal polyps (CRSwNP), a relative accumulation of cluster of differentiation (CD)8+ T cells over CD4+ T cells occurs in nasal polyps compared with the peripheral blood. Nasal CD8+ T cells and CD4+ T cells predominantly present an effector memory phenotype. Immunological studies have reported that memory T cells recirculate from the tissues to the peripheral blood and a high percentage of these T cells persist within the tissue. The aim of the present study was to characterize CD69+ sphingosine‑1‑phosphate receptor 1 (S1PR1)‑ tissue resident memory T cells (Trm) in the polyps of patients with CRSwNP. Tissue and blood samples were collected from 10 patients undergoing nasal sinus surgery. Expression of specific extra‑ and intracellular molecules were analyzed using multicolor flow cytometry. A significantly higher level of CD8+ T cells than CD4+ T cells was present in nasal polyps, while significantly more CD4+ T cells than CD8+ T cells were detected in the peripheral blood of patients with CRSwNP. The frequency of CD69+ T cells was significantly higher in CD8+ and CD4+ T cells in nasal polyps compared with the peripheral blood. The frequency of CD69+ S1PR1‑ Trm was also significantly higher in CD4+ and CD8+ T cells from nasal polyps compared with the peripheral blood. Within polyps, the frequency of CD69+ S1PR1‑ Trm was again significantly higher in CD8+ compared with CD4+ T cells. In summary, a significantly higher frequency of CD69+ S1PR1‑ T cells was observed in the nasal polyps compared with the peripheral blood in patients with CRSwNP. The results of the present study suggest that local regulation of the immune response occurs within nasal polyps. As such, Trm should be considered a potential stimulus in the pathogenesis of nasal polyps. However, the role of Trm in nasal polyps as a pathogenic trigger of the local inflammatory reaction requires further investigation.

Impact and Modulations of Peripheral and Edaphic B Cell Subpopulations in Chronic Rhinosinusitis With Nasal Polyposis

Objectives

The pathophysiological mechanisms of chronic rhinosinusitis with nasal polyposis (CRSwNP) still are discussed controversially. Regulatory B cells (B_reg) are responsible for the suppression of T cell activity: deficiencies for B_reg have been demonstrated to contribute to autoimmune disorders, e.g., systemic lupus erythematosus. In order to evaluate the influence of B cell subpopulations, especially B_reg, on the etiology of this disease, the aim of this study was to characterize subpopulations of peripheral and edaphic B cells in CRSwNP.

Methods

Polypoid tissue and blood samples were collected from 10 patients undergoing paranasal sinus surgery and lymphocytes were analyzed by multicolor flow cytometry.

Results

There was a significantly lower frequency of B cells in nasal polyps compared to peripheral blood mononuclear cells (PBMC) in patients with CRSwNP. Mature resting B cells were the main population within B cells in PBMC, and memory B cells in nasal polyps. Remarkably, B_reg and mature B cells significantly decreased in nasal polyps compared to PBMC. Memory B cells significantly increased and represented the main subpopulation in nasal polyps in patients with CRSwNP.

Conclusion

In this study a detailed contemporary characterization of B cell subpopulations in patients with CRSwNP is presented. The influence of edaphic B cells could play a key role in the maintenance of this chronic infectious disease.

Complications of the Middle Cranial Fossa Approach for Acoustic Neuroma Removal

OBJECTIVE

To analyze postoperative complications after microsurgery for acoustic neuroma (AN) via the middle fossa approach (MFA).

MATERIALS AND METHODS

In total, 203 consecutive patients of a tertiary skull base referral center at a university hospital were included in this retrospective chart and database analysis. All patients had undergone primary microsurgery at the Otorhinolaryngology department via MFA between December 2005 and October 2014. Postoperative complications were documented during the inpatient stay and outpatient follow-up.

RESULTS

Overall, 41 complications were registered in 35 patients. The most common was cerebrospinal fluid (CSF) leakage in 13% of the patients. Bleeding complications were documented in seven patients: two cerebellar bleedings, one subdural and one epidural hematoma, two hematomas of the skin, and one bleeding through the closed wound. Two patients experienced meningitis and one patient had a transient ischemic attack. Furthermore, three cases of deep vein thrombosis occurred, which led to a lethal pulmonary embolism in one case. One patient sustained temporary palsy of the vocal fold and another reported antibiotic-associated diarrhea.

CONCLUSION

Acoustic neuroma surgery via the MFA can be conducted with low morbidity and mortality. The most common complication is CSF leakage, which can be treated in most cases in a stepwise conservative manner. Severe adverse events that may require revision surgery are very scarce (1%).

Characterization of T-cell subpopulations in patients with chronic rhinosinusitis with nasal polyposis

Background:

There is an ongoing discussion concerning the potential origins of chronic rhinosinusitis with nasal polyposis (CRSwNP).

Objective:

The aim of this study was to quantify subpopulations of T cells in peripheral blood and nasal polyps in CRSwNP to examine their influence on the etiology of this disease.

Methods:

Tissue and blood samples were collected from 11 patients who underwent nasal sinus surgery, and these samples were analyzed by multicolor flow cytometry.

Results:

There was a significantly lower frequency of CD4⁺ T-helper (Th) cells and a significantly higher frequency of CD8⁺ T cells among lymphocytes isolated from nasal polyps compared with peripheral blood mononuclear cells (PBMC). In both T-cell subpopulations, a shift mainly from naive T cells among peripheral blood lymphocytes toward an effector memory and terminally differentiated subtype predominance in nasal polyps was observed. Among CD4⁺ T cells, the frequencies of cluster of differentiation (CD) 45RA- Forkhead-Box-Protein P3high (FoxP3^high) cytotoxic T-lymphocyte-associated Protein 4high (CTLA-4^high) activated regulatory T (T_reg) cells, and CD45RA- Forkhead-Box-Protein P3low (FoxP3^low) memory T cells were significantly increased in nasal polyps compared with PBMC.

Conclusion:

In this study, we presented a detailed characterization of CD4⁺ and CD8⁺ T-cell subpopulations in patients with CRSwNP. CD8⁺ T cells were more prominent in nasal polyps than in CD4⁺ T cells. Both nasal CD8⁺ T cells and CD4⁺ T cells predominantly had an effector memory phenotype. Among CD4⁺ T cells, activated T_reg cells were increased in nasal polyps compared with PBMC. The data point toward a local regulation of T-cell composition within the microenvironment of nasal polyps, which might be further exploited in the future to develop novel immunotherapeutic strategies.

Development of Human Salivary Gland-Like Tissue In Vitro

The loss of salivary gland function caused by radiation therapy of the head and neck is a serious condition and it affects a patient's quality of life. The current lack of effective therapies demands new options to be explored. This study tested whether human salivary gland epithelial cells (SGECs) could be successfully cultured on a decellularized porcine gut matrix (SIS-muc) in both mono- and coculture with microvascular endothelial cells (mvECs). By performing immunofluorescence imaging, transmission as well as scanning electron microscopy (SEM), quantitative polymerase chain reaction (qPCR), and an amylase enzyme assay, it was investigated as to what extent the three-dimensional (3D)-cultured cells could maintain their molecular differentiation and the production of working α-amylase (α-AMY) compared with two-dimensional (2D) culture. In both 3D mono- and coculture, SGECs were successfully cultured and formed acinar-like structures. Those findings were confirmed by SEM imaging. Immunofluorescence imaging revealed that 3D-cultured cells expressed α-AMY, Claudin-1 (CL-1), and water channel protein aquaporin-5 (AQP-5). Two-dimensional-cultured cells only were positive for α-AMY. Real time (RT)-qPCR analysis showed that α-AMY relative gene expression was higher in both 3D mono- and coculture than in 2D culture. In α-AMY enzyme assay, cocultured SGECs showed about 25 times increased enzyme activity compared with 2D-cultured cells. In conclusion, the SIS-muc combined with endothelial coculture seems a suitable culture setting for the tissue engineering of functional human salivary gland tissue.

Genotoxic effects of zinc oxide nanoparticles in nasal mucosa cells are antagonized by titanium dioxide nanoparticles

Titanium dioxide nanoparticles (TiO₂-NPs) and zinc oxide nanoparticles (ZnO-NPs) are often used in sunscreens and other consumer products due to their photoprotective properties. However, concern exists regarding them possibly causing cyto- and genotoxic effects. The aim of this study was to assess cyto- and genotoxicity of these nanomaterials after single or combined exposure. For this purpose, a battery of cell culture test systems for human nasal mucosa (monolayer, air-liquid interface and mini organ culture) were exposed to 0.1-20μg/ml of TiO₂- and ZnO-NPs alone and in combination. Cytotoxicity was measured by the MTT assay, and DNA damage and repair capacity were investigated using the comet assay. TiO₂-NPs did not exhibit any cyto- or genotoxic potential within the tested concentrations. However, results of the study indicated cyto- and genotoxicity resulting from ZnO-NPs. The genotoxicity could be antagonized by TiO₂-NPs. Furthermore, the DNA repair capacity after ZnO-NP-induced DNA damage was enhanced by TiO₂-NPs. The adsorption of dissolved zinc ions onto TiO₂-NPs is discussed as the major antagonistic mechanism. The combination of both metal oxide nanoparticles interferes with the genotoxicity of ZnO-NPs and should be discussed as a reasonable and safe alternative to the sole use of ZnO-NPs in consumer products.

[Treatment of nasolacrimal duct obstruction from the otorhinolaryngologist's perspective]

BACKGROUND

Epiphora is the classic symptom of nasolacrimal duct obstruction, particularly among elderly people. Dacryocystorhinostomy (DCR) via external (Toti) and endonasal (West) approaches are well-established surgical treatments.

OBJECTIVE

The aim of the present article is to describe the etiology and diagnostics of nasolacrimal duct obstruction. Furthermore, treatment modalities are discussed according to the current literature, with particular consideration of the otorhinolaryngologist's perspective.

MATERIALS AND METHODS

A search of the current literature focused on the past 5 years was performed in PubMed.

RESULTS

Several retrospective and prospective randomized studies describe the external and endonasal DCR approaches as safe surgical procedures, with high success rates of around 90 %. The endoscope is standardly used for visualization during the endonasal approach. Powered instruments such as diamond drills enable generation of a large rhinostomy, even in very hard bone. The application of silicone stents does not confer a significant additional advantage in terms of postoperative success rates.

CONCLUSION

DCR is a safe surgical procedure with high success rates. It can be strongly recommended for patients suffering from intra- or post-saccular nasolacrimal duct obstruction. Furthermore, the external and endonasal approaches (according to Toti and West, respectively) are comparable techniques. The use of silicone stents is indicated only in special cases.

The Proinflammatory Potential of Nitrogen Dioxide and Its Influence on the House Dust Mite Allergen Der p 1

Asthma and allergies are both major global health problems with an increasing prevalence, and environmental data implicate an influence of air pollutants on their development. The present study focuses on the influence of nitrogen dioxide (NO2) and the major allergen of the house dust mite Der p 1 on human nasal epithelial cells of nonallergic patients in vitro. Nasal epithelial mucosa samples of 11 donors were harvested during nasal air passage surgery and cultured as an air-liquid interface. Exposure to 0.1, 1 and 10 ppm NO2 or synthetic air as a control was performed for 1 h. Subsequently, the cells were exposed to Der p 1 for 24 h. The release of interleukin (IL)-6 and IL-8 was measured by ELISA, and the production of IL-6 mRNA and IL-8 mRNA was measured by RT-PCR. NO2 exposure resulted in a concentration-dependent release of IL-6, but not IL-8 release. The coexposure of 0.1 ppm NO2 and Der p 1, or 1 ppm NO2 and Der p 1 significantly increased both IL-6 and IL-8 release. Exposure to NO2, Der p 1, or their combination, did not significantly influence the production of IL-6 or IL-8 mRNA. In conclusion, NO2 increases the release of inflammatory cytokines in human nasal epithelial cells, especially in coexposure with Der p 1, as a mechanism of allergotoxicology.

Nicotine causes genotoxic damage but is not metabolized during long-term exposure of human nasal miniorgan cultures

Human nasal miniorgan cultures (MOC) are a useful tool in ecogenotoxicology. Repetitive exposure to nicotine showed reversible DNA damage, and stable CYP2A6 expression was demonstrated in nasal MOC in previous investigations. The aim of the present study was to evaluate the genotoxic effect of nicotine in nasal MOC after chronic nicotine exposure, and to monitor possible metabolism capacities. MOC were dissected from human nasal mucosa and cultured under standard cell culture conditions. MOC were exposed to nicotine for 3 weeks at concentrations of 1 μM and 1 mM. The concentrations were chosen based on nicotine plasma levels in heavy smokers, and possible concentrations used in topical application of nicotine nasal spray. DNA damage was assessed by the comet assay at days 7, 14 and 21. Concentrations of nicotine and cotinine were analyzed in cell culture medium by gas chromatography/mass spectrometry to determine a possible metabolism of nicotine by MOC. Distinct DNA damage in MOC could be demonstrated after 1 week of exposure to 1 μM and 1 mM nicotine. This effect decreased after 2 and 3 weeks with no statistically relevant DNA migration. No nicotine metabolism could be detected by changes in nicotine and cotinine concentrations in the supernatants. This is the first time genotoxic effects have been evaluated in nasal MOC after chronic nicotine exposure for up to 3 weeks. Genotoxic effects were present after 1 week of culture with a decrease over time. Down-regulation of nicotinic acetylcholine receptors, which are expressed in nasal mucosa, may be a possible explanation. The lack of nicotine metabolism in this model could be explained by the functional loss of CYP2A6 during chronic nicotine exposure. Further investigations are necessary to provide a more detailed description of the underlying mechanisms involved in DNA damage by nicotine.

Nicotine derived genotoxic effects in human primary parotid gland cells as assessed in vitro by comet assay, cytokinesis-block micronucleus test and chromosome aberrations test

Genotoxic effects of nicotine were described in different human cells including salivary gland cells. Based on the high nicotine concentration in saliva of smokers or patients using therapeutic nicotine patches, the current study was performed to evaluate the genotoxic potential of nicotine in human salivary gland cells. Therefore, primary salivary gland cells from 10 patients undergoing parotid gland surgery were exposed to nicotine concentrations between 1 μM and 1000 μM for 1 h in the absence of exogenous metabolic activation. The acinar phenotype was proven by immunofluorescent staining of alpha-amylase. Genotoxic effects were evaluated using the Comet assay, the micronucleus test and the chromosome aberration test. Cytotoxicity and apoptosis were determined by trypan blue exclusion test and Caspase-3 assay. Nicotine was able to induce genotoxic effects in all three assays. The chromosome aberration test was the most sensitive and increases in numerical and structural (chromatid-type and chromosome-type) aberrations were seen at ≥1 μM, whereas increases in micronuclei frequency were detected at 10 μM and DNA damage as measured in the Comet assay was noted at >100 μM. No cytotoxic damage or influence of apoptosis could be demonstrated. Nicotine as a possible risk factor for tumor initiation in salivary glands is still discussed controversially. Our results demonstrated the potential of nicotine to induce genotoxic effects in salivary gland cells. These results were observed at saliva nicotine levels similar to those found after oral or transdermal exposure to nicotine and suggest the necessity of careful monitoring of the use of nicotine in humans.

Nanoparticle-induced photocatalytic head and neck squamous cell carcinoma cell death is associated with autophagy

Aim: To characterize molecular mechanisms underlying photocatalytic cell death of head and neck squamous cell carcinoma (HNSCC) by zinc oxide nanoparticles (ZnO-NPs). Materials & methods: Human HNSCC-derived FaDu cells were incubated with ZnO-NPs followed by UVA-1 irradiation. Cytotoxicity was assessed by MTT assay and annexin-V propidium iodide test. Autophagy was detected by autophagosome accumulation, conversion of light chain 3 I to II, and lysosomal activity. The generation of reactive oxygen species was measured using the 2´,7´-dichlorofluorescein-diacetate test. Results: Apoptosis-independent cytotoxic effects were induced by 0.2- and 2-µg/ml ZnO-NPs and UVA-1. FaDu cells promoted autophagosome formation. Significantly elevated light chain 3 II and reactive oxygen species were seen after the combined application of both ZnO-NPs and UVA-1 as photocatalytic treatment. Autophagy probably mediates cell survival under UVA-1 or ZnO-NP exposure alone but induces self-digestive cell death after combined treatment. Conclusion: The effect of autophagy on HNSCC viability after nanoparticle-induced photocatalytic treatment seems to depend on the impact of the physicochemical trigger.

Original submitted 14 June 2012; Revised submitted 19 November 2012; Published online 3 June 2013

[Postoperative complications after surgery for vestibular schwannoma via the MCF approach]

BACKGROUND

The aim of this study was to analyze complications after surgery for vestibular schwannoma (VS) via the middle cranial fossa (MCF) approach.

PATIENTS AND METHODS

112 consecutive patients have been operated on via MCF approach in our department between October 2005 and March 2011. Postoperative complications have been registered during hospital stay as well as during outpatient follow-up.

RESULTS

25 complications occurred in 20 patients, most common was a CSF leak (12%). In 9 cases leakage stopped after conservative management. 3 patients needed lumbar drainage and 1 patient had to undergo revision-surgery. 6 patients suffered from hemorrhage: 2 cerebellar bleedings, 1 subdural hematoma, 2 hematomas of the scalp and 1 bleeding of the sutured wound. All bleedings except the case with subdural hematoma could be managed conservatively. Furthermore, one case of meningitis and one transient ischemic attack were observed. 3 patients suffered from a deep venous thrombosis which led to a lethal pulmonary embolism in one case.

CONCLUSIONS

Surgery for VS via the MCF approach is an established method with satisfying functional results and a low -complication rate. CSF leak is a common complication (12%) that can be managed conservatively in most of the cases. Severe complications that may lead to revision surgery are rare (2%). Persisting sequels of these complications occur in less than 1% of the cases.

Nitrogen dioxide is genotoxic in urban concentrations

In the discussion on toxic and genotoxic thresholds of air pollutants such as nitrogen dioxide (NO2), realistically low urban concentration ranges are of major interest. For NO2, the WHO defines the annual limit value as corresponding to 0.02 ppm. In the present study, the toxicity and genotoxicity of NO2 is set at a concentration under this limit value and examined in human nasal epithelium at different exposure durations in vitro. Nasal epithelial mucosa samples of 10 donors were harvested during nasal air passage surgery and cultured as an air-liquid interface. Exposure to 0.01 ppm NO2 or synthetic air as a control was performed for 0.5, 1, 2 and 3 h. Analysis included the caspase-3 ELISA, the single cell microgel electrophoresis (comet) assay and the micronucleus assay. The caspase-3 activity was not influenced by NO2 exposure, DNA strand fragmentation correlated with exposure durations to NO2 at 0.01 ppm NO2, and no cytotoxic effects such as apoptosis, necrosis or disturbances of cell proliferation were present. However, micronucleus induction as a sign of genotoxicity at an exposure duration of 3 h could be shown. Shorter exposures did not induce micronucleus formation. In summary, genotoxicity of NO2 could be demonstrated at a common urban concentration in vitro, but a threshold of NO2 genotoxicity could not be defined based on the present experiments.

Incomplete tumour control following DNA vaccination against rat gliomas expressing a model antigen

Background

Vaccination against tumour-associated antigens is one approach to elicit anti-tumour responses. We investigated the effect of polynucleotide (DNA) vaccination using a model antigen (E. coli lacZ) in a syngeneic gliosarcoma model (9L).

Methods

Fisher 344 rats were vaccinated thrice by intramuscular injection of a lacZ-encoding or a control plasmid in weekly intervals. One week after the last vaccination, lacZ-expressing 9L cells were implanted into the striatum.

Results

After 3 weeks, in lacZ-vaccinated animals the tumours were significantly smaller than in control-vaccinated animals. In cytotoxic T cell assays lysis rates of >50 % could only be observed in a few of the lacZ-vaccinated animals. This response was directed against lacZ-expressing and parental 9L cells but not against syngeneic MADB 106 adenocarcinoma cells. In Elispot assays interferon-γ production was observed upon stimulation with 9LlacZ and 9L wild-type but not MADB 106 cells. This response was higher for lacZ-immunized animals. All animals revealed dense infiltrates with CD8+ lymphocytes and, to a lesser extent, with NK cells. CD25-staining indicated cells possibly associated with the maintenance of peripheral tolerance to self-antigens. All tumours were densely infiltrated by microglia consisting mostly of ramified cells. Only focal accumulation of macrophage-like cells expressing ED1, a marker for phagocytic activity, was observed.

Conclusion

Prophylactic DNA vaccination resulted in effective but incomplete suppression of brain tumour formation. Mechanisms other than cytotoxic T cell responses as measured in the generally used in vitro assays appear to play a role in tumour suppression.

Assessment of nicotine-induced DNA damage in a genotoxicological test battery

The role of the tobacco-alkaloid nicotine in tumour biology is widely discussed in the literature. Due to a strong capacity to induce angiogenesis, a pro-mutagenic potential in non-tumour and cancer cells, and a pro- and anti-apoptotic influence, nicotine seems to promote the growth of established tumours. However, results indicating DNA damage and genetic instability associated with nicotine have been contradictory thus far. A variety of markers and endpoints of genotoxicity are required to characterize the genotoxic potential of nicotine. Induction of DNA single- and double-strand breaks, the formation of micronuclei, and the induction of sister chromatid exchange and chromosome aberrations represent possible genotoxicological endpoints at different cellular levels. Human lymphocytes were exposed to nicotine concentrations between 1μM and 1mM for 24h in vitro. The comet assay, the cytokinesis-block micronucleus test, the chromosome aberration (CA) test, and the sister chromatid exchange (SCE) test were then applied. Viability and apoptosis were measured by flow cytometry in combination with the annexin V-propidium iodide staining test. In this test setting, no enhanced DNA migration was measured by the comet assay. An increase in the micronucleus frequency was detected at a concentration of 100μM nicotine without affecting the frequency of apoptotic cells. A distinct genotoxic effect was determined by the CA test and the SCE test, with a significant increase in CA and SCE at a concentration of 1μM. In the annexin V test, nicotine did not influence the proportion of apoptotic or necrotic cells. The current data indicating the induction of CA by nicotine underscore the necessity of ongoing investigations on the potential of nicotine to initiate mutagenesis and tumour promotion. Taking into account the physiological nicotine plasma levels in smokers or in nicotine-replacement therapy, particularly the long-term use of nicotine should be critically discussed.

Short-term severe thyroid hormone deficiency does not influence sleep parameters

PURPOSE

The influence of short-term severe thyroid hormone deficiency on sleep is currently still unknown. Several studies have demonstrated an effect of long-term hypothyroidism on sleep disorders due to anatomical changes of the pharynx or body mass. The aim of this preliminary study, however, is to evaluate the changes in sleep patterns of patients with short-term hypothyroidism to elucidate the isolated effect of thyroid hormone withdrawal before anatomical changes can potentially occur.

METHODS

Ten patients with differentiated thyroid carcinoma were enrolled in this study. Two patients discontinued the study and one patient was finally excluded due to obesity, so that the datasets of seven patients were available for study analysis. During the course of carcinoma treatment, each patient had previously undergone total thyroidectomy and I-131 remnant ablation. Polysomnographic measurements were performed twice: (1) over the course of two consecutive nights during severe thyroid hormone deficiency after levothyroxine withdrawal and prior to further diagnostics and therapy and (2) during euthyroidism after substitution with levothyroxine.

RESULTS

Comparison of the Epworth Sleepiness Scale during hypo- and euthyroidism for each patient revealed no statistically significant difference. Furthermore, the comparison of polysomnographic parameters like (1) apnea-hypopnea index, (2) the duration of various sleep stages, (3) duration of rapid eye movement sleep, (4) latency until rapid eye movement sleep, (5) total sleep time, (6) periodic leg movements, and (7) arousal index showed no statistically significant differences between the hypothyroid or euthyroid state.

CONCLUSIONS

We conclude that, in this preliminary experimental setting, short-term severe thyroid hormone deficiency per se does not cause sleep disturbances and a feeling of fatigue as described in other studies may be due to changes in perception or brain metabolism during hypothyroidism.

[Direct recording from cochlear nerve via a ball-electrode in transtemporal acoustic neuroma surgery]

BACKGROUND

Intraoperative monitoring (IOM) of the cochlear nerve function during acoustic neuroma surgery is employed to assist in preserving hearing. So far, Auditory Brain-stem Response (ABR) is considered to be an optimal method for intraoperative monitoring in transtemporal approach. The aim of this study was to perform direct recording of the cochlear nerve action potential after resection of the tumor by using a ball-electrode and to evaluate the use of this method in predicting the postoperative hearing. The obtained data were compared to the simultaneous ABR results and to the postoperative hearing.

MATERIAL AND METHODS

In 2009, 38 patients have undergone acoustic Neuroma Surgery at the ENT University hospital, Wuerzburg. In 33 patients an intraoperative ABR as well as a direct measurement from the cochlear nerve using a ball electrode were performed. In 5 patients the postoperative hearing was predicted using the direct measurement at the cochlear nerve only.

RESULTS

The direct recording from the cochlear nerve gave very robust responses. Even in cases where ABR recording was not possible, the identification of clear cochlear nerve action potential could still be reached. Using the direct recordings from the cochlear nerve to predict the post operative hearing turned out to have a sensitivity of 100% and a specificity of 70%.

CONCLUSIONS

These results show that intraoperative monitoring with direct recording from the cochlear nerve via a ball-electrode in transtemporal approaches offers a valuable method to predict the postoperative hearing. Further investigation will be made to provide additional information.

Analysis of nicotine-induced DNA damage in cells of the human respiratory tract

Epithelium of the upper and lower airways is a common origin of tobacco-related cancer. The main tobacco alkaloid nicotine may be associated with tumor progression. The potential of nicotine in inducing DNA mutations as a step towards cancer initiation is still controversially discussed. Different subtypes of nicotinic acetylcholine receptors (nAChR) are expressed in human nasal mucosa and a human bronchial cell line representing respiratory mucosa as a possible target for receptor-mediated pathways. In the present study, both cell systems were investigated with respect to DNA damage induced by nicotine and its mechanisms. Specimens of human nasal mucosa were harvested during surgery of the nasal air passage. After enzymatic digestion over night, single cells were exposed to an increasing nicotine concentration between 0.001 mM and 4.0mM. In a second step co-incubation was performed using the antioxidant N-acetylcysteine (NAC) and the nAChR antagonist mecamylamine. DNA damage was assessed using the alkali version of the comet assay. Dose finding experiments for mecamylamine to evaluate the maximal inhibitory effect were performed in the human bronchial cell line BEAS-2B with an increasing mecamylamine concentration and a constant nicotine concentration. The influence of nicotine in the apoptotic pathway was evaluated in BEAS-2B cells with the TUNEL assay combined with flow cytometry. After 1h of nicotine exposure with 0.001, 0.01, 0.1, 1.0 and 4.0mM, significant DNA damage was determined at 1.0mM. Further co-incubation experiments with mecamylamine and NAC were performed using 1.0mM of nicotine. The strongest inhibitory effect was measured at 1.0mM mecamylamine and this concentration was used for co-incubation. Both, the antioxidant NAC at a concentration of 1.0mM, based on the literature, as well as the receptor antagonist were capable of complete inhibition of the nicotine-induced DNA migration in the comet assay. A nicotine-induced increase or decrease in apoptosis as assessed by the TUNEL assay in BEAS-2B could not be detected. These results support the hypothesis that oxidative stress is responsible for nicotine-induced DNA damage. Similar results exist for other antioxidants in different cell systems. The decrease in DNA damage after co-incubation with a nAChR antagonist indicates a receptor-dependent pathway of induction for oxidative stress. Further investigations concerning pathways of receptor-mediated DNA damage via nAChR, the role of reactive oxygen species and apoptosis in this cell system will elucidate underlying mechanisms.

Repetitive exposure to zinc oxide nanoparticles induces dna damage in human nasal mucosa mini organ cultures

Data on the toxicological properties of zinc oxide nanoparticles (ZnO-NPs) is incomplete. ZnO-NPs may enter humans via inhalation or ingestion. The aim of the current study was to evaluate ZnO-NP-induced genotoxicity in three-dimensional (3D) mini organ cultures (MOCs) of human nasal mucosa following repeated exposure to ZnO-NP and regeneration. Nasal MOCs of 10 patients and ZnO-NPs were cultivated for one week and then characterized by electron microscopy. Nasal MOCs were partially covered by ciliated epithelium after one week of cultivation. ZnO-NPs were distributed to the cytoplasm and the nucleus. MOCs were exposed once, twice, or three times to 0.1 or 5 μg/ml of ZnO-NPs for 1 hr per exposure and were then evaluated for cytotoxicity and genotoxicity. MOCs were cultivated for 24 hr after the triple ZnO-NP exposure to allow for regeneration. ZnO-NP exposure did not result in significant cytotoxicity or apoptosis, as determined by trypan blue exclusion and caspase-3 activity, respectively. A significant increase in DNA damage was detected following repetitive exposure compared to single exposure to ZnO-NPs at 5 μg/ml, but not 0.1 μg/ml ZnO-NPs. At both concentrations of ZnO-NP, DNA fragmentation increased after 24 hr of regeneration. In contrast, DNA damage which was induced by the positive control, methyl methanesulfonate, was significantly reduced after 24-hr regeneration. Thus, our results suggest that repetitive exposure to low concentrations of ZnO-NPs results in persistent or ongoing DNA damage.

Nanosized titanium dioxide particles do not induce DNA damage in human peripheral blood lymphocytes

Industrial application of titanium dioxide nanoparticles (TiO(2) -NPs) as an additive in pharmaceutical and cosmetic products is increasing. However, the knowledge about the toxicity of this material is still incomplete and data concerning health and environmental safety and results of recent studies on TiO(2) nanotoxicology are inconsistent. The in vitro geno- and cytotoxicity of TiO(2) -NPs in the anatase crystal phase was evaluated in human peripheral blood lymphocytes from 10 male donors. Initially, transmission electron microscopy (TEM) was performed to describe particle morphology and size, the degree of particle aggregation, and the intracellular distribution. Cells were exposed to nanoparticles in increasing concentrations of 20, 50, 100, and 200 μg/ml for 24 hr. Cytotoxic effects were analyzed by trypan blue exclusion test and the single-cell microgel electrophoresis (comet) assay was applied to detect DNA double-strand breakage. TiO(2) -NPs were sphere shaped with a diameter of 15-30 nm. Despite dispersive pretreatment, a strong tendency to form aggregates was observed. Particles were detected in the cytoplasm of lymphocytes, but also a transfer into the nucleus was seen. The trypan blue exclusion test did not show any decrease in lymphocyte viability, and there was no evidence of genotoxicity in the comet assay for any of the tested concentrations. In conclusion, TiO(2) -NPs reached the cytoplasm as well as the nucleus and did not induce cyto- or genotoxic effects in human peripheral blood lymphocytes. Complement investigations on different human cell systems will be performed to estimate the biocompatibility of TiO(2) -NPs. Environ. Mol. Mutagen.

Zinc oxide nanoparticles induce photocatalytic cell death in human head and neck squamous cell carcinoma cell lines in vitro

The aim of this study was to determine the photocatalytic effects of zinc oxide (ZnO) NPs in combination with UVA-1 in human head and neck squamous cell carcinoma (HNSCC) cell lines in vitro. NP characteristics and intracellular distribution were described by transmission electron microscopy (TEM). After pre-incubation with ZnO NPs in concentrations of 0.002-20 µg/ml, the HNSCC cell lines HLaC 78 and UD-SCC 7A as well as primary oral mucosa cells (pOMCs) were treated with UVA-1. Cell survival and vitality was observed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazoliumbromide-(MTT)-assay and fluorescein diacetate test. Apoptosis was assessed by annexin-V propidium iodide flow cytometry. Intranuclear distribution of the rod-shaped particles was observed in 3.5% of HNSCC and in 0.5% of pOMCs. UVA-1 irradiation of 15 min in combination with 0.2 and 2 µg/ml of ZnO NP dispersion was shown to reduce the vitality of cancer cell lines significantly in comparison to cells without NP exposure or UVA-1 treatment only. For HLaC 78, a significant reduction in viable cells was already seen at 10 min of UVA-1 treatment and a ZnO NP concentration of 2 µg/ml. Flow cytometry indicated that cell death occurred primarily through necrosis. In pOMCs, vitality was not influenced either by UVA-1 treatment or ZnO NP exposure up to 2 µg/ml or a combination of both. ZnO NPs showed cytotoxicity at 20 µg/ml without UVA-1. Due to their photocatalytic properties, ZnO NPs may induce cell death in human HNSCC cell lines in vitro. Further studies will evaluate a possible benefit in adjuvant cancer therapy.

Cytotoxic, genotoxic and pro-inflammatory effects of zinc oxide nanoparticles in human nasal mucosa cells in vitro

Despite increasing application of zinc oxide nanoparticles (ZnO-NPs) for industrial purposes, data about potential toxic properties is contradictory. The current study focused on the cyto- and genotoxicity of ZnO-NPs in comparison to ZnO powder in primary human nasal mucosa cells cultured in the air-liquid interface. Additionally, IL-8 secretion as a marker for pro-inflammatory effects was measured. Particle morphology and intracellular distribution were evaluated by transmission electron microscopy (TEM). ZnO-NPs were transferred into the cytoplasm in 10% of the cells, whereas an intranuclear distribution could only be observed in 1.5%. While no cyto- or genotoxicity could be seen for ZnO powder in the dimethylthiazolyl-diphenyl-tetrazolium-bromide (MTT) test, the trypan blue exclusion test, and the single-cell microgel electrophoresis (comet) assay, cytotoxic effects were shown at a ZnO-NP concentration of 50 μg/ml (P<0.01). A significant enhancement in DNA damage was observed starting from ZnO-NP concentrations of 10 μg/ml (P<0.05) in comparison to the control. IL-8 secretion into the basolateral culture medium was increased at ZnO-NP concentrations of 5 μg/ml (P<0.05), as shown by ELISA. Our data indicates cyto- and genotoxic properties as well as a pro-inflammatory potential of ZnO-NPs in nasal mucosa cells. Thus, caution should be taken concerning their industrial and dermatological application. Additionally, further investigation on repetitive NP exposure is needed to estimate the impact of repair mechanisms.

Increase in tumor size following intratumoral injection of immunostimulatory CpG-containing oligonucleotides in a rat glioma model

The immunosuppressive environment of malignant gliomas is likely to suppress the anti-tumor activity of infiltrating microglial cells and lymphocytes. Macrophages and microglial cells may be activated by oligonucleotides containing unmethylated CpG-motifs, although their value in cancer immunotherapy has remained controversial. Following injection of CpG-containing oligonucleotides (ODN) into normal rat brain, we observed a local inflammatory response with CD8+ T cell infiltration, upregulation of MHC 2, and ED1 expression proving the immunogenic capacity of the CpG-ODN used. This was not observed with a control ODN mutated in the immunostimulatory sequence (m-CpG). To study their effect in a syngeneic tumor model, we implanted rat 9L gliosarcoma cells into the striatum of Fisher 344 rats. After 3 days, immunostimulatory CpG-ODN, control m-CpG-ODN, or saline was injected stereotactically into the tumors (day 3 group). In another group of animals (day 0 group), CpG-ODN were mixed with 9L cells prior to implantation without further treatment on day 3. After 3 weeks, the animals were killed and the brains and spleens were removed. Rather unexpectedly, the tumors in several of the animals treated with CpG-ODN (both day 0 and day 3 group) were larger than in saline or m-CpG-ODN treated control animals. The tumor size in CpG-ODN-treated animals was more variable than in both control groups. This was associated with inflammatory responses and necrosis which was observed in most tumors following CpG treatment. This, however, did not prevent excessive growth of solid tumor masses in the CpG-treated animals similar to the control-treated animals. Dense infiltration with microglial cells resembling ramified microglia was observed within the solid tumor masses of control- and CpG-treated animals. In necrotic areas (phagocytic), activation of microglial cells was suggested by ED1 expression and a more macrophage-like morphology. Dense lymphocytic infiltrates consisting predominantly of CD8+ T cells and fewer NK cells were detected in all tumors including the control-treated animals. Expression of perforin serving as a marker for T cell or NK cell activation was detected only on isolated cells in all treatment groups. Tumors of all treatment groups revealed CD25 expression indicating T cells presumed to maintain peripheral tolerance to self-antigens. Cytotoxic T cell assays with in vitro restimulated lymphocytes ((51)chromium release assay) as well as interferon-gamma production by fresh splenocytes (Elispot assay) revealed specific responses to 9L cells but not another syngeneic cell line (MADB 106 adenocarcinoma). Surprisingly, the lysis rates with lymphocytes from CpG-ODN-treated animals were lower compared to control-treated animals. The tumor size of individual animals did not correlate with the response in both immune assays. Taken together, our data support the immunostimulatory capacity of CpG-ODN in normal brain. However, intratumoral application proved ineffective in a rat glioma model. CpG-ODN treatment may not yield beneficial effects in glioma patients.

Aspects of nitrogen dioxide toxicity in environmental urban concentrations in human nasal epithelium

Cytotoxicity and genotoxicity of nitrogen dioxide (NO(2)) as part of urban exhaust pollution are widely discussed as potential hazards to human health. This study focuses on toxic effects of NO(2) in realistic environmental concentrations with respect to the current limit values in a human target tissue of volatile xenobiotics, the epithelium of the upper aerodigestive tract. Nasal epithelial cells of 10 patients were cultured as an air-liquid interface and exposed to 0.01 ppm NO(2), 0.1 ppm NO(2), 1 ppm NO(2), 10 ppm NO(2) and synthetic air for half an hour. After exposure, genotoxicity was evaluated by the alkaline single-cell microgel electrophoresis (Comet) assay and by induction of micronuclei in the micronucleus test. Depression of proliferation and cytotoxic effects were determined using the micronucleus assay and trypan blue exclusion assay, respectively. The experiments revealed genotoxic effects by DNA fragmentation starting at 0.01 ppm NO(2) in the Comet assay, but no micronucleus inductions, no changes in proliferation, no signs of necrosis or apoptosis in the micronucleus assay, nor did the trypan blue exclusion assay show any changes in viability. The present data reveal a possible genotoxicity of NO(2) in urban concentrations in a screening test. However, permanent DNA damage as indicated by the induction of micronuclei was not observed. Further research should elucidate the effects of prolonged exposure.

Intracellular distribution, geno- and cytotoxic effects of nanosized titanium dioxide particles in the anatase crystal phase on human nasal mucosa cells

Nanomaterials are defined as substances with at least one dimension smaller than 100nm in size and are used for a multitude of purposes. Titanium dioxide nanoparticles (TiO(2)-NPs) are an important material used as an additive in pharmaceutical and cosmetic products. Due to their high surface-to-mass index, TiO(2) nanoparticles show different physical and chemical characteristics compared to the bulk substance. The knowledge about geno- or cytotoxic effects of TiO(2)-NPs is incomplete since existing studies show contrary results. Human nasal mucosa cells were obtained from 10 donors and exposed to TiO(2)-NPs in increasing concentrations of 10, 25, 50 und 100mug/ml. Transmission electron microscopy (TEM) was applied to document particle morphology and size distribution, the degree of particle aggregation and the distribution of particles in inter- and intracellular spaces. Furthermore, DNA fragmentation and cytotoxicity caused by TiO(2)-NPs were evaluated. DNA strand breakage was detected by single-cell microgel electrophoresis (comet) assay. Cytotoxic effects were analyzed by trypan blue exclusion test and fluorescein diacetate (FDA) assay. TiO(2) particles used in this study were mainly nanosized but also showed a strong tendency to aggregate in spite of sonication of the suspension. Particles entered the cytoplasm in 11% and the cell nucleus in 4%. The trypan blue exclusion test and the FDA assay did not show any loss of cell viability. In the comet assay, there was no evidence of increased DNA damage for TiO(2)-NPs. In this pilot project, no cyto- or genotoxic effects could be shown for TiO(2)-NPs on human nasal epithelial cells. Further investigations will focus on a variety of metal oxide nanoparticles to describe the biocompatibility in the human organism.

Nicotine induces DNA damage in human salivary glands

The tobacco alkaloid nicotine is responsible for addiction to tobacco and supposed to contribute to tobacco carcinogensis, too. Recently, genotoxic effects of nicotine have been reported in human cells from blood and upper aerodigestive tract. Because of nicotine accumulation in saliva, the study of possible in vitro genotoxic effects of nicotine have been extended to human salivary gland cells. Specimens of parotid glands of 10 tumor patients were obtained from tumor-free tissue. Single cells were prepared by enzymatic digestion immediately after surgery and exposed for 1h to 0.125-4.0mM of nicotine. Possible genotoxic effects were determined by the Comet assay using the % DNA in tail (DT) as a reliable indicator of DNA damage. Nicotine induced a significant dose-dependent increase of DNA migration in parotid gland single-cells. The mean DT was 1.12-fold (0.125mM) to 2.24-fold (4.0mM) higher compared to control. The lowest concentration eliciting significant DNA damage within 1h, 0.25mM nicotine, is only 10-fold higher than maximal concentrations of nicotine reported in saliva after unrestricted smoking. Although conclusive evidence for a carcinogenic potential of nicotine is still lacking, the safety of long-term nicotine replacement therapy should be carefully monitored.