Nicotine-induced endocytosis of amiloride-sensitive sodium channels in human nasal epithelium

A Systematic Review of the Association between Cigarette Smoke Exposure and Chronic Rhinosinusitis

Objectives Cigarette smoking and passive smoke exposure have been associated with chronic rhinosinusitis (CRS). Our goal in this systematic review was to (1) determine if there was a strong correlative effect in large population studies between cigarette smoke exposure and the prevalence of CRS, (2) investigate pathogenic mechanisms of cigarette smoke in the upper airway, and (3) determine if a history of cigarette smoking affects the medical and surgical outcomes of CRS. Data Sources MEDLINE, Embase, Cochrane CENTRAL, Web of Science SCI and CPCI-S, and websites. Methods A comprehensive literature review and quantitative meta-analysis of studies based on the PRISMA protocol and examining the relationship between cigarette smoke exposure and CRS was performed. A search strategy was developed using various terms such as sinusitis, rhinitis, rhinosinusitis, and smoking. The articles were categorized by (1) epidemiology, (2) pathophysiology, and (3) outcomes. Data regarding study design, population/setting, methods, and bias were collected. Results The initial search generated 2621 titles/abstracts with 309 articles undergoing secondary review and 112 articles for final review. We determined that there is a strong correlation between active and passive cigarette smoke with the prevalence of CRS. Cigarette smoke challenge to sinonasal epithelia results in the release of inflammatory mediators and altered ciliary beat frequency. Pediatric patients exposed to secondhand smoke appear to have particularly poor outcomes. Conclusion There is clear evidence that cigarette smoke is related to CRS, but longitudinal and mechanistic studies are required to determine a causative effect. This information is critical for greater understanding of CRS health outcomes.

Amiloride-sensitive sodium currents in fungiform taste cells of rats chronically exposed to nicotine

Many studies have demonstrated that chronic exposure to nicotine, one of the main components of tobacco smoke, has profound effects on the functionality of the mammalian taste system. However, the mechanisms underlying nicotine action are poorly understood. In particular no information is available on the chronic effect of nicotine on the functioning of taste cells, the peripheral detectors which transduce food chemicals into electrical signals to the brain. To address this issue, I studied the membrane properties of rat fungiform taste cells and evaluated the effect of long-term exposure to nicotine on the amiloride-sensitive sodium currents (ASSCs). These currents are mediated by the epithelial sodium channels (ENaC) thought to be important, at least in part, in the transduction of salty stimuli. Patch-clamp recording data indicated that ASSCs in taste cells from rats chronically treated with nicotine had a reduced amplitude compared to controls. The pharmacological and biophysical analysis of ASSCs revealed that amplitude reduction was not dependent on changes in amiloride sensitivity or channel ionic permeability, but likely derived from a decrease in the activity of ENaCs. Since these channels are considered to be sodium receptors in taste cells, my results suggest that chronic exposure to nicotine hampers the capability of these cells to respond to sodium ions. This might represent a possible cellular mechanism underlying the reduced taste sensitivity to salt typically found in smokers.

The additive effect of ethanol and extract of cigarette smoke on rabbit esophagus epithelium

AIM

The combination of alcohol and smoking takes a place in the epidemiology and pathogenesis of gastroesophageal reflux disease and squamous cancers of the esophagus. Therefore, a study was designed to assess the impact of these agents alone or in combination on the structure and function of squamous epithelium of rabbit esophagus.

METHODS

Rabbit esophageal epithelium was mounted in Ussing Chambers, exposed luminally for ethanol (1-10%), extract of cigarette smoke (EOCS) and combinations or sequential application of these agents. An in-vivo model was also used to mimic conditions more representative of human alcohol consumption.

RESULTS

Ethanol (1-10%) dose dependently decreased tissue resistance. Extract of cigarette smoke caused a reduction on transepithelial potential difference (PD), short circuit current. Combinations of EOCS, ethanol (5-10% EtOH and EOCS 1-2) showed a more pronounced decrease than agents alone, mainly the result of EOCS. In vivo studies showed that EOCS administration dropped PD dose dependently. In-vivo 10% EtOH, EOCS-2 dropped PD (55%) similar to in-vitro 5% EtOH, EOCS-1. The effect was clearly additive; boluses of 10% ethanol (36%) and EOCS-2 (17%) decreased PD and combination of agents resulted in a 55% drop on PD which is a very similar decrease compared to the sum of the separate effects of agents (53%).

CONCLUSION

Ethanol affected the barrier and cigarette smoke altered ion transport on rabbit esophageal epithelium under conditions reflecting human consumption. Results were consistent with in vivo and in vitro conditions except higher concentrations were needed in vivo. When applied, these agents showed an additive effect. Ethanol predisposed the tissue to the effect of EOCS.

The use of human nasal in vitro cell systems during drug discovery and development

The nasal route is widely used for the administration of drugs for both topical and systemic action. At an early stage in drug discovery and during the development process, it is essential to gain a thorough insight of the nasal absorption potential, metabolism and toxicity of the active compound and the components of the drug formulation. Human nasal epithelial cell cultures may provide a reliable screening tool for pharmaco-toxicological assessment of potential nasal drug formulations. The aim of this review is to give an overview of the information relevant for the development of a human nasal epithelial cell culture model useful during drug discovery and development. A primary goal in the development of in vitro cell culture systems is to maintain differentiated morphology and biochemical features, resembling the original tissue as closely as possible. The potential and limitations of the existing in vitro human nasal models are summarized. The following topics related to cell culture methodology are discussed: (i) primary cultures versus cell lines; (ii) cell-support substrate; (iii) medium and medium supplements; and (iv) the air-liquid interface model versus liquid-liquid. Several considerations with respect to the use of in vitro systems for pharmaceutical applications (transport, metabolism, assessment of ciliary toxicity) are also discussed.

[Evaluation of rhinologic signs among smokers]

OBJECTIVE

As well as others usually irritative factors, cigarettes smoke has many medical consequences that aren't well known at the present time. The aim of this study is to describe the rhinologic signs caused by cigarettes consumption.

MATERIAL AND METHODS

Two groups (smoker and control) of 20 patients (10 men and 10 women) were contituted. Individual patient status was evaluated by questionnaire, analogic visual scale, clinical examination and rhinomanometry.

RESULTS

Nasal resistances, nasal obstruction and posterior rhinorrhea evaluated by, analogic visual scale are significantly higher in the smoker group as compared to the control group (Mann-Whitney test; total nasal resistance: p<0.00001, uninasal resistances: p<0.00001, nasal obstruction: p<0.0001, posterior rhinorrhea: p<0.01). They are significantly higher among smokers of 20 cigarettes a day than among smokers of 10 cigarettes a day.

DISCUSSION

The control group was completly safe of rhinologic signs, so we used it to confirm the normal values of nasal resistances. Posterior rhinorrhea and nasal obstruction are 2 important signs which should be researched in smokers; its severity is correlates with cigarettes consumption.

CONCLUSION

Tobacco is an important irritative factor for nasal mucosa.