Effects of whole cigarette smoke on human beta defensins expression and secretion by oral mucosal epithelial cells

Attenuation of NLRP3 Inflammasome by Cigarette Smoke is Correlated with Decreased Defense Response of Oral Epithelial Cells to Candida albicans

BACKGROUND

It is well recognized that both smoke and Candida infection are crucial risk factors for oral mucosal diseases. The nucleotide-binding domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome and its downstream effectors, interleukin (IL)-1β and IL-18, are pivotal to the host defense against Candida and other pathogens.

METHODS

The present study was designed to explore the effects of cigarette smoke and C. albicans on the NLRP3 inflammasome and its downstream signal pathway via in vitro cell model. Oral epithelial cells (Leuk-1 cells) were exposed to cigarette smoke extract (CSE) for 3 days and/or challenged with C. albicans.

RESULTS

Microscopically, Leuk-1 cells exerted a defense response to C. albicans by markedly limiting the formation of germ tubes and microcolonies. CSE clearly eliminated the defense response of Leuk-1 cells. Functionally, CSE repressed NLRP3 inflammasome, and IL-1β and IL-18 activation induced by C. albicans in Leuk-1 cells.

CONCLUSION

Our results suggested that in oral epithelial cells, the NLRP3 inflammasome might be one of the target pathways by which CSE attenuates innate immunity and leads to oral disorders.

Antimicrobial Peptides and Interleukins in Cleft Soft Palate

Cleft palate is one of the most common and well-studied congenital anomalies; however, the role of protective tissue factors in its pathophysiology is still debated. The aim of our study was to evaluate interleukin and antimicrobial peptide appearance and distribution in cleft palate. Eight soft palate samples were obtained during veloplasty procedures. Immunohistochemical staining was applied to detect HBD-2-, HBD-3-, HBD-4-, LL-37-, IL-10-, and CD-163-positive cells via light microscopy. For statistical evaluation, the Mann-Whitney U test and Spearman's rank correlation coefficient were used. A significant difference between study groups was observed for HBD-2 and IL-10 in epithelial and connective tissue as well as HBD-4 in connective tissue. The number of HBD-3-positive cells was moderate in the patients, and few were observed in the controls. The number of LL-37-positive cells varied from a moderate amount to a numerous amount in both study groups, whilst CD-163 marked a moderate number of positive cells in patients, and a few-to-moderate amount was observed in the controls. Numerous correlations between studied factors were revealed in cleft tissues. The increase in antimicrobial peptides HBD-2 and HBD-4 and anti-inflammatory cytokine IL-10 suggested a wide compensatory elevation of the local immune system against cleft-raised tissue changes. The correlations between the studied factors (HBD-2, HBD-3, HBD-4, LL-37, and IL-10) proved the synergistic involvement of common local defense factors in postnatal cleft palate morphopathogenesis.

Human beta-defensin-1 rs2738047 polymorphism is associated with shisha smoking risk among Saudi population

Human β-defensin (HBD), a member of the antimicrobial peptides, is essential for respiratory epithelial cells' microbial defense, and is affected by cigarette smoking (CS). Its expression is upregulated by stimulation from microbes or inflammation. Genetic polymorphisms in the HBD-1 gene have been implicated in the development of various smoking-related diseases, including chronic obstructive pulmonary disease and asthma. Thus, we sought to analyze possible associations between HBD-1 single-nucleotide polymorphism (SNP) in HBD-1 gene and CS in ethnic Saudi Arabian subjects. Variants rs1047031 (C/T), rs1799946 (C/T), rs2738047 (C/T), and rs11362 (C/T) were investigated by genotyping 575 blood specimens from males and females, smokers/non-smokers: 288/287. The CT and CT+TT genotypes of rs1799946 presented an ~5-fold increased correlation with CS among the female smokers, compared with the female controls (OR = 5.473, P = 0.02003; and OR = 5.211, P = 0.02028, respectively), an observation similar to rs11362 SNP in female smokers, but with protective effects in TT genotype, compared with the CC reference allele (OR = 0.143, P = 0.04368). In shisha smokers, the heterozygous CT and the CT/TT genotype of rs2738047 polymorphism showed the same results with ~3-fold increased correlation with CS (OR = 2.788; P = 0.03448), compared with the cigarette smokers category. No significant association was shown in genotypic distributions and allelic frequencies of rs1047031. Further investigations, including large study samples, are required to investigate the effects of shisha on human beta-defensin expression and protein levels.

Epithelial Barrier Dysfunction in Chronic Respiratory Diseases

Mucosal surfaces are lined by epithelial cells, which provide a complex and adaptive module that ensures first-line defense against external toxics, irritants, antigens, and pathogens. The underlying mechanisms of host protection encompass multiple physical, chemical, and immune pathways. In the lung, inhaled agents continually challenge the airway epithelial barrier, which is altered in chronic diseases such as chronic obstructive pulmonary disease, asthma, cystic fibrosis, or pulmonary fibrosis. In this review, we describe the epithelial barrier abnormalities that are observed in such disorders and summarize current knowledge on the mechanisms driving impaired barrier function, which could represent targets of future therapeutic approaches.

Potential Suppressive Effect of Nicotine on the Inflammatory Response in Oral Epithelial Cells: An In Vitro Study

Smoking is a well-recognized risk factor for oral mucosal and periodontal diseases. Nicotine is an important component of cigarette smoke. This study aims to investigate the impact of nicotine on the viability and inflammatory mediator production of an oral epithelial cell line in the presence of various inflammatory stimuli. Oral epithelial HSC-2 cells were challenged with nicotine (10⁻⁸–10⁻² M) for 24 h in the presence or absence of Porphyromonas gingivalis lipopolysaccharide (LPS, 1 µg/mL) or tumor necrosis factor (TNF)-α (10⁻⁷ M) for 24 h. The cell proliferation/viability was determined by MTT assay. Gene expression of interleukin (IL)-8, intercellular adhesion molecule (ICAM)-1, and β-defensin was assayed by qPCR. The production of IL-8 protein and cell surface expression of ICAM-1 was assessed by ELISA and flow cytometry, respectively. Proliferation/viability of HSC-2 cells was unaffected by nicotine at concentrations up to 10⁻³ M and inhibited at 10⁻² M. Nicotine had no significant effect on the basal expression of IL-8, ICAM-1, and β-defensin. At the same time, it significantly diminished P. gingivalis LPS or the TNF-α-induced expression levels of these factors. Within the limitations of this study, the first evidence was provided in vitro that nicotine probably exerts a suppressive effect on the production of inflammatory mediators and antimicrobial peptides in human oral epithelial cells.

Mainstream cigarette smoke induces autophagy and promotes apoptosis in oral mucosal epithelial cells

OBJECTIVE

This study aimed to investigate the effects of cigarette smoke (extract) on autophagy and apoptosis in oral mucosa epithelial cells.

METHODS

The effects of cigarette smoke extract (CSE) on autophagy and apoptosis in oral epithelial cells were studied in vivo and in vitro. Leuk-1 cells were administered cigarette smoke extract or chloroquine (CQ) and rapamycin (RAPA) at different concentrations. Immunoblotting, immunofluorescence, Western blotting and flow cytometry were used to detect autophagy-related protein and apoptosis levels, screen the optimal concentration and stimulation time, and verify the effect of CSE stimulation on autophagy and apoptosis in leuk-1 cells. Meanwhile, autophagy expression in epithelial cells from the local oral tissues of mice who had smoked for 5 months was detected.

RESULTS

Under CS stimulation, LC3-II and Beclin-1, the key proteins of leuk-1 autophagy, were upregulated in a concentration- and time-dependent manner. In addition, CS significantly upregulated the expression of Cleaved caspase-3 (C-casp3), a protein involved in apoptosis. However, under stimulation with CQ, autophagy in leuk-1 cells was inhibited and the level of C-casp3 and the apoptosis rate were increased. The autophagy activator RAPA significantly reduced the level of C-casp3 and apoptosis rate in leuk-1 cells.

CONCLUSION

The results of this study indicate that CS can simultaneously activate autophagy and apoptosis in mouse and human oral epithelial cells, that autophagy inhibition can aggravate the CSE-triggered apoptosis of oral epithelial cells, and that autophagy induction can inhibit the CSE-triggered apoptosis of oral epithelial cells. Autophagy is suggested to play a protective role in the CSE-induced apoptosis of oral epithelial cells. Further studies are needed to explore the concrete mechanisms underlying the regulatory effects of CS-induced apoptosis and to gain in-depth insight into the complex interactions between apoptosis and autophagy.

Assessment of antimicrobial potential of substances isolated from some wastes of meat processing industry

The slaughter of farm animals generates a large number of by-products. Meat waste management includes various methods, but cost-effective technologies are still in priority. This manuscript reports the results of the study of antimicrobial activity of substances isolated from such wastes of meat processing industry as bovine and pork mucous membranes and epithelial tissues. Proteomic study included two-dimensional electrophoresis with following mass spectrometric identification. Antimicrobial activity against L. monocytogenes, P. aeruginosa and S. aureus of neutralized native extracts and after enzymatic treatment as well as its ultrafiltrates was determined by flow cytometry with EvaGreen and PI dyes. It was shown that a large number of histones were found in bovine mucous membranes as well as several tissue-specific proteins, which would be a precursor of bioactive peptides. Bovine mucous membranes of the tongue and nasal cavity possessed the greatest activity in relation to P. aeruginosa, the rate of surviving cells decreased to 22.0%. Bovine mucous membranes of the rectum and the oral cavity, submandibular lymph nodes, pig mucous membranes of the larynx, tongue, lips, and rectum increased dead cells count up to 40% of all cells. Bovine nasal mucosa and pork mucous of labial cavity possessed the greatest activity against S. aureus, the rate of surviving cells did not exceed 10.0%. Determination of antimicrobial action against L. monocytogenes of native samples and treated with trypsin showed that bovine mucous membranes of the rectum and oral cavity, pork mucosa of the lips and submandibular glands were the most active. Treatment with trypsin or ultrafiltration demonstrated different effects on activity of samples. It was shown the perspectivity of recycling of such type of by-products into effective and demanded substances which can be used, for example, in the food industry as an alternative to chemical preservatives.

Long-term cigarette smoking suppresses NLRP3 inflammasome activation in oral mucosal epithelium and attenuates host defense against Candida albicans in a rat model

Cigarette smoke (CS) exposure and Candida albicans (C. albicans) infection are epidemiological risk factors for oral diseases, such as oral leukoplakia (OLK). Smoking-induced inflammation and immune modulation are potentially important mechanisms in the development of diseases, although the biological mechanism of how CS exposure impacts host defenses has not been elucidated. The critical components of host defense, NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome and IL-1β, are required for normal immune function in order to efficiently control infection. This paper studies the molecular mechanism of the immune-suppressive effect of CS on the oral mucosa of animal models. Rats were exposed to intraoral CS to simulate active human smoking and/or to C. albicans for 3 months or 6 months, and their ability to control the infection of C. albicans was examined. The CS and C. albicans co-exposed rats showed early stage lesions of OLK and were more susceptible to C. albicans than those in the C. albicans-exposed group. CS caused a reduced expression of the NLRP3 inflammasome and diminished the secretion of IL-1β and IL-18 maturing by the NLRP3 inflammasome, which were stimulated by C. albicans. CS and immune suppression appear to be closely interwoven at multiple levels. This is the first animal model of active smoking through the mouth, and these data demonstrate that CS suppresses the protective immune response to C. albicans in rats through the NLRP3 inflammasome.

Effects of active and passive smoking on salivary cytokines levels in rats: A pilot study

Cigarette smoking is an established risk factor for some oral diseases. As an essential fluid in the oral cavity, saliva is crucial to maintain oral health. Relative to active smoking, there are very few studies assessing the effect of passive smoking on salivary cytokines levels. In the present study, we established the rat models by the means of the intraoral cigarette smoking or whole body cigarette smoke exposure to simulate human active or passive smoking, respectively. The effects of active or passive smoking on salivary cytokines levels were assessed by using ProcartaPlex multiplex immunoassays. The results of the current study indicated that both active and passive smoking diminished the body weights of rats and increased the levels of some blood counts. Intriguingly, active smoking enhanced the salivary levels of IL-6 and IL-12 p70 and passive smoking elevated the salivary IL-6 level. Moreover, active smoking appeared to have a more prominent activation effect on the salivary IL-6 level. It was noted that active or passive smoking had no significant effect on the salivary IFN-γ level. Active or passive smoking could have potential effects on the salivary levels of some pro-inflammatory cytokines.

The effect of tobacco smoke exposure on the generation of reactive oxygen species and cellular membrane damage using co-culture model of blood brain barrier with astrocytes

Brain tissue is known to be vulnerable to the exposure by tobacco smoke. Tobacco smoke can induce generation of reactive oxygen species (ROS), causing inflammatory activity and blood-brain barrier (BBB) impairment. The aim of the present study was to investigate the effect of tobacco smoke on cell cytotoxicity, generation of ROS, and cellular membrane damage in astrocytes and BBB using a co-culture system. Cell viability of U373MG cells was reduced in a dose-dependent manner, ranging from 96.7% to 40.3% by tobacco smoke condensate (TSC). Cell viability of U373MG co-cultured with human brain microvascular endothelial cells (HBMECs) was 104.9% at the IC50 value of TSC. Trans-epithelial electric resistance values drastically decreased 80% following 12-h incubation. The value was maintained until 48 h and then increased at 72-h incubation (85%). It then decreased to 75% at 120 h. Generation of ROS increased in a dose-dependent manner, ranging from 102.7% to 107.9%, when various concentrations of TSC (4-16 mg/mL) were administered to the U373MG monoculture. When TSC was added into U373MG co-cultured with HBMECs, production of ROS ranged from 101.7% to 102.6%, slightly increasing over 12 h. Maximum exposure-generated ROS of 104.8% was reached at 24 h. Cell cytotoxicity and oxidative stress levels in the U373MG co-culture model system with HBMECs were lower than U373MG monoculture. HBMECs effectively acted as a barrier to protect the astrocytes (U373MG) from toxicity of TSC.

Benefits of Bifidobacterium animalis subsp. lactis Probiotic in Experimental Periodontitis

BACKGROUND

This study evaluates effects of topical administration of probiotic bacteria of the genus Bifidobacterium on experimental periodontitis (EP) in rats.

METHODS

Thirty-two rats were divided into groups C (control; without EP), EP (EP only), C-HN019 (control+probiotic), and EP-HN019 (EP+probiotic). On day 0 of the experiment, animals of groups EP and EP-HN019 received cotton ligatures around mandibular first molars (MFMs). In groups C-HN019 and EP-HN019, 1 mL of suspensions containing Bifidobacterium animalis subsp. lactis (B. lactis) HN019 was topically administered in the subgingival region of MFMs on days 0, 3, and 7. In groups C and EP, topical administrations were performed using a sham suspension (without probiotic). All animals were euthanized at day 14. Gingival tissue, hemimandibles, and oral biofilm were collected. Data were statistically analyzed (P <0.05).

RESULTS

Group EP presented greater bone porosity, trabecular separation, and connective tissue attachment loss (CTAL) as well as reduced bone volume than all other groups (P <0.05). In group EP-HN019, there were greater proportions of Actinomyces and Streptococcus-like species and lower proportions of Veillonella parvula, Capnocytophaga sputigena, Eikenella corrodens, and Prevotella intermedia-like species than group EP. Group EP-HN019 presented greater expressions of osteoprotegerin and β-defensins than group EP (P <0.05). Group EP presented greater levels of interleukin-1β and receptor activator of nuclear factor-kappa B ligand than group EP-HN019 (P <0.05).

CONCLUSION

Topical use of B. lactis HN019 promotes a protective effect against alveolar bone loss and CTALs attributable to EP in rats, modifying immunoinflammatory and microbiologic parameters.

NOD1 agonist iE-DAP reverses effects of cigarette smoke extract on NOD1 signal pathway in human oral mucosal epithelial cells

Smoking is a well-known risk factor for many systemic diseases and oral disorders. Smoking has been recognized to cause diminished defense, persistent inflammation and result in disease development. Nucleotide binding oligomerization domain 1 (NOD1) signal pathway plays a key role in innate immune and tissue homeostasis. Our recent studies confirmed that cigarette smoke extract (CSE) could inhibit NOD1 expression and affect expression levels of crucial molecules of NOD1 signaling in oral mucosal epithelial cells. In the present study, immortalized human oral mucosal epithelial (Leuk-1) cells were treated with CSE, iE-DAP (NOD1 agonist), CSE + iE-DAP, respectively. Western blotting analysis demonstrated that iE-DAP triggered NOD1 expression of leuk-1 cells in a dose-dependent manner. iE-DAP also reversed the suppressive effect of CSE on NOD1 expression and prevented the overactivation of RIP2 and P-NF-κB following CSE exposure. Real-time PCR and ELISA results confirmed that iE-DAP reversed CSE-mediated effects on the mRNA levels and releases of IL-6, IL-8, TNF-α and IFN-γ by Leuk-1 cells. Taken together, our results indicated that NOD1 activation with iE-DAP could reverse CSE-mediated effects on NOD1 signaling in human oral mucosal epithelial cells.