Neurogenic and Endothelial Nitric Oxide Regulates Blood Circulation in Lingual and Other Oral Tissues:

Hyposalivation in patients with psoriasis: Association with severity, inflammatory, and anti-inflammatory cytokine biomarkers of the disease

The aim of the study is to expound the effect of psoriasis on salivary glands by evaluating the secretion of saliva and salivary cytokine biomarkers in patients with psoriasis. This study was conducted by recruiting 120 subjects that included 60 patients diagnosed clinically with active psoriasis and 60 healthy controls who were age and gender matched to psoriatic subjects. Unstimulated whole saliva was collected from all the subjects by spitting method, and levels of tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), interleukin-2 (IL-2), and IL-10 (IL-10) were determined via enzyme-linked immunosorbent assay (BT Lab, Shanghai, China). Secretion of saliva in psoriasis patients was considerably reduced than in healthy controls. The concentrations of pro-inflammatory cytokines (TNF-α, IFN-γ, and IL-2) were significantly increased, whereas level of anti-inflammatory cytokine (IL-10) was markedly decreased in the saliva of psoriasis patients with hyposalivation compared to healthy subjects. Our results demonstrated significant negative correlation of salivary flow rates with the disease severity. No significant correlations were obtained between salivary levels of tested cytokines and salivary flow rates in our study. Findings of the study reflect inflammation of salivary glands with reduced salivary flow rates in psoriasis patients. The inflammatory responses in salivary gland tissues by virtue of increased pro-inflammatory cytokines concentrations together with lower anti-inflammatory cytokine levels may have a role in affecting the saliva secretion in psoriasis patients. Secretion of unstimulated saliva in psoriasis patients decreases with the severity and duration of the disease.

Oral microbiome characterization in oral mucositis patients-A systematic review

BACKGROUND

Oral mucositis (OM) is a severe and common adverse effect of cancer treatment. The oral microbiome appears to play a role on the onset and severity of OM. Therefore, this systematic review aims to characterize the oral dysbiosis associated with OM.

METHODS

The PRISMA checklist was followed and PubMed, Web of Science, and Scopus were screened for clinical studies characterizing the oral microbiome alterations in patients with OM.

RESULTS

From a total of 2500 articles retrieved, we included nine articles in this systematic review. Certain types of bacteria, as Fusobacterium, were recognized as predictors of the onset of OM. In addition, it was reported that patients with severe OM presented a reduction in alpha-diversity, an increase in beta-diversity. The abundance of some taxa significantly changed with OM severity, with Bacillota phylum and genera Leptotrichia, Actinomyces, and Prevotella decreasing and Treponema increasing with disease progression. Additionally, during cancer treatment, changes in the oral microbiome have been observed in OM patients, with an increase in Candida and nosocomial pathogens, including Staphylococcus species.

CONCLUSION

Our review indicates that cancer treatment can significantly alter the oral microbiome, with more pronounced changes observed in patients with severe OM in all relevant oral phyla, but more pronounced in Bacillota phylum.

Ethanol- and Cigarette Smoke-Related Alternations in Oral Redox Homeostasis

Alcohol abuse as well as smoking cigarettes has been proven to negatively affect the oral environment. The aim of this work was to provide a systematic review of the literature on the influence of ethanol and cigarette smoking on oral redox homeostasis. A search was performed for scientific articles indexed in the PubMed, Medline and Web of Science databases. We identified 32,300 articles, of which 54 were used for the final review, including the results from 2000 to 2021. Among the publications used to write this article, n = 14 were related to the influence of alcohol consumption (clinical studies n = 6, experimental studies n = 8) and n = 40 were related to the influence of smoking (clinical studies n = 33, experimental studies n = 7) on oral redox homeostasis. The reviewed literature indicates that alcohol abusers and smokers are more likely to suffer from salivary gland dysfunction, as well as develop precancerous lesions due to DNA damage. Compared to alcohol abstainers and non-smokers, alcohol drinkers and smokers are also characterized by a deterioration in periodontal health measured by various indicators of periodontal status. In summary, alcohol abuse and smoking are associated with disrupted oral redox homeostasis, which may lead not only to tooth loss, but also contribute to various adverse effects related to mental health, digestive processes and chronic inflammation throughout the human body.

Nicotine and vascular dysfunction

Cigarette smoking is the single most important risk factor for the development of cardiovascular diseases (CVDs). However, the role of nicotine, the addictive component of all tobacco products, in the development of CVD is incompletely understood. Although increased public awareness of the harms of cigarette smoking has successfully led to a decline in its prevalence, the use of electronic cigarettes (e-cig) or electronic nicotine delivery system has increased dramatically in recent years because of the perception that these products are safe. This review summarizes our current knowledge of the expression and function of the nicotinic acetylcholine receptors in the cardiovascular system and the impact of nicotine exposure on cardiovascular health, with a focus on nicotine-induced vascular dysfunction. Nicotine alters vasoreactivity through endothelium-dependent and/or endothelium-independent mechanisms, leading to clinical manifestations in both cigarette smokers and e-cig users. In addition, nicotine induces vascular remodelling through its effects on proliferation, migration and matrix production of both vascular endothelial and vascular smooth muscle cells. The purpose of this review is to identify critical knowledge gaps regarding the effects of nicotine on the vasculature and to stimulate continued nicotine research.

The Controversy Persists: Is There a Qualification Criterion to Utilize Inhaled Nitric Oxide in Pre-term Newborns?

Inhaled nitric oxide (iNO) use in premature newborns remains controversial among clinicians. In 2014, the American Academy of Pediatrics, Committee on Fetus and Newborn released a statement that the available data do not support routine iNO use in pre-term newborns. Despite the absence of significant benefits, 2016 California data showed that clinicians continue to utilize iNO in pre-term infants. With studies as recent as January 2017, the Cochrane review confirmed no major advantages of iNO in pre-term newborns. Still, it recognized that a subset of pre-term infants with pulmonary hypertension (PHTN) had not been separately investigated. Furthermore, recent non-randomized controlled trials have suggested that iNO may benefit specific subgroups of pre-term newborns, especially those with PHTN, prolonged rupture of membranes, and antenatal steroid exposure. Those pre-term infants who showed a clinical response to iNO had increased survival without disability. These findings underscore the need for future studies in pre-term newborns with hypoxemic respiratory failure and PHTN. This review will discuss the rationale for using iNO, controversies regarding the diagnosis of PHTN, and additional novel approaches of iNO treatment in perinatal asphyxia and neonatal resuscitation in the pre-term population < 34 weeks gestation.

Physiopathology of nitric oxide in the oral environment and its biotechnological potential for new oral treatments: a literature review

OBJECTIVES

A narrative review on the NO properties and their relationship with the oral environment describing NO's molecular origin, role, and perspectives regarding oral pathological, physiological, and regenerative processes for future applications and possible use as prevention or treatment in dentistry.

MATERIALS AND METHODS

Pubmed was searched using the word "nitric oxide." Reviews, clinical studies, and experimental studies were eligible for the screening process. Similar search procedures were then performed with the additional search words "conservative dentistry," "orthodontics," "endodontics," "implants," "periodontics," "oral cancer," "pulp revascularization," and "oral surgery." Furthermore, references of included articles were examined to identify further relevant articles.

RESULTS

There is a relationship between NO production and oral diseases such as caries, periodontal diseases, pulp inflammation, apical periodontitis, oral cancer, with implants, and orthodontics. Studies on this relationship and uses of NO, in diagnosis, prevention, and treatment, are being developed. Also, some NO and oral cavity patents have already registered.

CONCLUSIONS

The understanding of how NO can interfere in oral health maintenance or disease processes can contribute to elucidate the disease development and optimize treatment approaches.

CLINICAL RELEVANCE

NO has considerable biotechnological potential and can contribute to improving diagnostics and treating the oral environment. As a biomarker, NO has an important role in the early diagnosis of diseases. Regarding treatments, NO can possibly be used as a regulator of inflammation, anti-biofilm action, replacing antibiotics, inducing apoptosis of cancerous cells, and contributing to the angiogenesis. All these studies are initial considerations regarding the relationship between NO and dentistry.

Enhanced Inflammation and Nitrosative Stress in the Saliva and Plasma of Patients with Plaque Psoriasis

Psoriasis is the most common inflammatory skin disease, characterized by the release ofproinflammatory cytokines from lymphocytes, keratinocytes, and dendritic cells. Although psoriasis is considered an immune-mediated inflammatory disease, its effect on secretory activity of salivary glands and quantitative composition of saliva is still unknown. The aim of this study was to evaluate the secretion of saliva as well as several selected inflammation and nitrosative stress biomarkers in unstimulated and stimulated saliva as well as plasma of psoriasis patients. We demonstrated that, with progressing severity and duration of the disease, the&nbsp; secretory function of the parotid and submandibular salivary glands is lost, which is&nbsp; manifested as decreased unstimulated and stimulated saliva secretion and reduced salivary amylase activity and total protein concentration. The levels of tumor necrosis factor-alpha (TNF-α), interleukin-2 (IL-2), and interferon-gamma (INF-α) were significantly higher, whereas interleukin-10 (IL-10) content was considerably lower in unstimulated and stimulated saliva of patients with psoriasis compared to the controls, and the changes increased with the disease duration. Similarly, we observed that the intensity of nitrosative stress in the salivary glands of psoriasis patients depended on the duration of the disease. By means of receiver operating characteristic (ROC) analysis, we showed that the evaluation of nitric oxide (NO), nitrotyrosine, and IL-2 concentration in non-stimulated saliva with high sensitivity and specificity differentiatedpsoriasis patients on the basis of the rate of saliva secretion (normal salivation vs. hyposalivation). In summary, the dysfunction of salivary glands in psoriasis patients is caused by inflammation and nitrosative stress.

Nitric Oxide in Dental Pulp Tissue: From Molecular Understanding to Clinical Application in Regenerative Endodontic Procedures

Nitric oxide (NO), which is synthesized by the enzyme NO synthase (NOS), is a versatile endogenous molecule with multiple biological effects on many tissues and organs. In dental pulp tissue, NO has been found to play multifaceted roles in regulating physiological activities, inflammation processes, and tissue repair events, such as cell proliferation, neuronal degeneration, angiogenesis, and odontoblastic differentiation. However, there is a deficiency of detailed discussion on the NO-mediated interactions between inflammation and reparative/regenerative responses in wounded dental pulp tissue, which is a central determinant of ultimate clinical outcomes. Thus, the purpose of this review is to outline the current molecular understanding on the roles of Janus-faced molecule NO in dental pulp physiology, inflammation, and reparative activities. Based on this knowledge, advanced physicochemical techniques designed to manipulate the therapeutic potential of NOS and NO production in endodontic regeneration procedures are further discussed. Impact statement The interaction between inflammation and reparative/regenerative responses is very important for regenerative endodontic procedures, which are biologically based approaches intended to replace damaged tissues. Inside dental pulp tissue, endogenous nitric oxide (NO) is generated mainly by immunocompetent cells and dental pulp cells and mediates not only inflammatory/immune activities but also signaling cascades that regulate tissue repair and reconstruction, indicating its involvement in both tissue destruction and regeneration. Thus, it is feasible that NO acts as one of the indicators and modulators in dental pulp repair or regeneration under physiological and pathological conditions.

Comparison of salivary nitric oxide and oral health in diabetic patients with and without xerostomia

BACKGROUND AND OBJECTIVE

Diabetes mellitus (DM) is a chronic multi-systemic metabolic disorder; diabetic patients are more prone to xerostomia and oral health problems than others. There are evidences that nitric oxide (NO) plays an important role in healthy salivary gland function, prevention of insulin resistance and progression of diabetes mellitus. The aim of this study was to compare the salivary NO level between type 2 diabetic (T2DM) patients with and without xerostomia.

METHODS

In this case control study, 70 patients with T2DM, which were matched according to age, sex, type of disease control, were enrolled conveniently. The subjects based on abeslang test were allocated to the two groups; 35 patients with xerostomia and 35 patients without xerostomia. Unstimulated whole saliva was collected by spitting method. NO levels was measured by ELISA method using Griess reaction. Data was analyzed using t-test, ANOVA and logistic regression analysis to examine the association of salivary NO and xerostomia.

RESULTS

The mean and standard deviation of salivary NO in the diabetic subjects with xerostomia was significantly lower than diabetic subjects without xerostomia (138 ± 94.58 μmol/L vs. 356.61 ± 302.81 μmol/L (P-value = 0.001). In logistic regression analysis, salivary NO level was associated with 0.994 fold decreased risk of xerostomia in diabetic subjects after adjustment for age, gender, FBS and HbA1c.

CONCLUSIONS

The present study indicates salivary nitric oxide level was a predictor of xerostomia in diabetic patients. More longitudinal studies are necessary to understand the association of salivary NO level with diabetes-induced xerostomia.

Endothelial dysfunction and vascular disease - a 30th anniversary update

The endothelium can evoke relaxations of the underlying vascular smooth muscle, by releasing vasodilator substances. The best-characterized endothelium-derived relaxing factor (EDRF) is nitric oxide (NO) which activates soluble guanylyl cyclase in the vascular smooth muscle cells, with the production of cyclic guanosine monophosphate (cGMP) initiating relaxation. The endothelial cells also evoke hyperpolarization of the cell membrane of vascular smooth muscle (endothelium-dependent hyperpolarizations, EDH-mediated responses). As regards the latter, hydrogen peroxide (H₂ O₂ ) now appears to play a dominant role. Endothelium-dependent relaxations involve both pertussis toxin-sensitive G_i (e.g. responses to α₂ -adrenergic agonists, serotonin, and thrombin) and pertussis toxin-insensitive G_q (e.g. adenosine diphosphate and bradykinin) coupling proteins. New stimulators (e.g. insulin, adiponectin) of the release of EDRFs have emerged. In recent years, evidence has also accumulated, confirming that the release of NO by the endothelial cell can chronically be upregulated (e.g. by oestrogens, exercise and dietary factors) and downregulated (e.g. oxidative stress, smoking, pollution and oxidized low-density lipoproteins) and that it is reduced with ageing and in the course of vascular disease (e.g. diabetes and hypertension). Arteries covered with regenerated endothelium (e.g. following angioplasty) selectively lose the pertussis toxin-sensitive pathway for NO release which favours vasospasm, thrombosis, penetration of macrophages, cellular growth and the inflammatory reaction leading to atherosclerosis. In addition to the release of NO (and EDH, in particular those due to H₂ O₂ ), endothelial cells also can evoke contraction of the underlying vascular smooth muscle cells by releasing endothelium-derived contracting factors. Recent evidence confirms that most endothelium-dependent acute increases in contractile force are due to the formation of vasoconstrictor prostanoids (endoperoxides and prostacyclin) which activate TP receptors of the vascular smooth muscle cells and that prostacyclin plays a key role in such responses. Endothelium-dependent contractions are exacerbated when the production of nitric oxide is impaired (e.g. by oxidative stress, ageing, spontaneous hypertension and diabetes). They contribute to the blunting of endothelium-dependent vasodilatations in aged subjects and essential hypertensive and diabetic patients. In addition, recent data confirm that the release of endothelin-1 can contribute to endothelial dysfunction and that the peptide appears to be an important contributor to vascular dysfunction. Finally, it has become clear that nitric oxide itself, under certain conditions (e.g. hypoxia), can cause biased activation of soluble guanylyl cyclase leading to the production of cyclic inosine monophosphate (cIMP) rather than cGMP and hence causes contraction rather than relaxation of the underlying vascular smooth muscle.

World Workshop on Oral Medicine VI: a systematic review of medication-induced salivary gland dysfunction

The aim of this paper was to perform a systematic review of the pathogenesis of medication-induced salivary gland dysfunction (MISGD). Review of the identified papers was based on the standards regarding the methodology for systematic reviews set forth by the World Workshop on Oral Medicine IV and the PRISMA statement. Eligible papers were assessed for both the degree and strength of relevance to the pathogenesis of MISGD as well as on the appropriateness of the study design and sample size. A total of 99 papers were retained for the final analysis. MISGD in human studies was generally reported as xerostomia (the sensation of oral dryness) without measurements of salivary secretion rate. Medications may act on the central nervous system (CNS) and/or at the neuroglandular junction on muscarinic, α-and β-adrenergic receptors and certain peptidergic receptors. The types of medications that were most commonly implicated for inducing salivary gland dysfunction were those acting on the nervous, cardiovascular, genitourinary, musculoskeletal, respiratory, and alimentary systems. Although many medications may affect the salivary flow rate and composition, most of the studies considered only xerostomia. Thus, further human studies are necessary to improve our understanding of the association between MISGD and the underlying pathophysiology.

Vascular nitric oxide: Beyond eNOS

As the first discovered gaseous signaling molecule, nitric oxide (NO) affects a number of cellular processes, including those involving vascular cells. This brief review summarizes the contribution of NO to the regulation of vascular tone and its sources in the blood vessel wall. NO regulates the degree of contraction of vascular smooth muscle cells mainly by stimulating soluble guanylyl cyclase (sGC) to produce cyclic guanosine monophosphate (cGMP), although cGMP-independent signaling [S-nitrosylation of target proteins, activation of sarco/endoplasmic reticulum calcium ATPase (SERCA) or production of cyclic inosine monophosphate (cIMP)] also can be involved. In the blood vessel wall, NO is produced mainly from l-arginine by the enzyme endothelial nitric oxide synthase (eNOS) but it can also be released non-enzymatically from S-nitrosothiols or from nitrate/nitrite. Dysfunction in the production and/or the bioavailability of NO characterizes endothelial dysfunction, which is associated with cardiovascular diseases such as hypertension and atherosclerosis.

Production and physiological role of NO in the oral cavity

Nitric oxide (NO) is a free radical which is produced from a wide variety of cells and tissues in the human body. NO is involved in the regulation of many physiological processes, such as vascular relaxation, neurotransmission, immune regulation, and cell death. NO is generated by nitric oxide synthase (NOS), which has three identified isoforms: neuronal type NOS (nNOS), endothelial type NOS (eNOS), and inducible type NOS (iNOS). Different isoforms are expressed depending on the organs, tissues, and cells, and investigation of the types and functions of enzymes expressed in various tissues is underway. The oral cavity is a space in which marked changes have been detected in NO levels, and each tissue is constantly influenced by NO. NO is a component of saliva and is produced by oral bacteria in the oral cavity and released by NOS expressed in oral mucosa. NOS isoforms expressed under normal conditions differ among the oral organs. In addition, the overexpression of NOS was involved in carcinogenesis and tumor growth progression. This review summarized the expression of NOS and functions of NO in oral cavity organs, and their roles in diseases and the influences of treatments.

The oral microbiome and nitric oxide homoeostasis

The tiny radical nitric oxide (NO) participates in a vast number of physiological functions including vasodilation, nerve transmission, host defence and cellular energetics. Classically produced by a family of specific enzymes, NO synthases (NOSs), NO signals via reactions with other radicals or transition metals. An alternative pathway for the generation of NO is the nitrate-nitrite-NO pathway in which the inorganic anions nitrate (NO(3)(-)) and nitrite (NO(2)(-)) are reduced to NO and other reactive nitrogen intermediates. Nitrate and nitrite are oxidation products from NOS-dependent NO generation but also constituents in our diet, mainly in leafy green vegetables. Irrespective of origin, active uptake of circulating nitrate in the salivary glands, excretion in saliva and subsequent reduction to nitrite by oral commensal bacteria are all necessary steps for further NO generation. This central role of the oral cavity in regulating NO generation from nitrate presents a new and intriguing aspect of the human microbiome in health and disease. In this review, we present recent advances in our understanding of the nitrate-nitrite-NO pathway and specifically highlight the importance of the oral cavity as a hub for its function.