Phagocytic functions of salivary neutrophils in oral mucous membrane diseases

Association of neutrophil defects with oral ulcers but undetermined role of neutrophils in recurrent aphthous stomatitis

Objective

Recurrent oral ulcers and severe periodontal diseases in patients with quantitative or qualitative neutrophil defects highlight the important role of neutrophils in maintaining oral mucosal barrier homeostasis. Recurrent aphthous stomatitis (RAS) is a common oral mucosal disease affecting up to 25% of the population, yet its etiopathogenesis remains unclear, and management is unsatisfactory. This review aims to gain insight into the pathogenesis of RAS.

Design

This narrative review examines the characteristics of oral and blood neutrophils, the associations between neutrophil defects and the occurrence of oral ulcers, and the evidence for the involvement of neutrophils in RAS. To conduct the review, relevant literature was searched in PubMed and Google Scholar, which was then thoroughly reviewed and critically appraised.

Results

Neutropenia, specifically a decrease in the number of oral neutrophils, impaired extravasation, and defective ROS production appear to be associated with oral ulcers, while defects in granule enzymes or NETosis are unlikely to have a link to oral ulcers. The review of the histopathology of RAS shows that neutrophils are concentrated in the denuded area but are latecomers to the scene and early leavers. However, the evidence for the involvement of neutrophils in the pathogenesis of RAS is inconsistent, leading to the proposal of two different scenarios involving either impaired or hyperactive neutrophils in the pathogenesis of RAS.

Effects of a chlorhexidine mouthwash on clinical parameters of gingivitis, dental plaque and oral polymorphonuclear leukocytes [PMN]

Histological features of oral inflammation include infiltration of polymorphonuclear leukocytes [PMN], however studies have not examined the effects of interventions mitigating inflammation on oral PMN. Methods: This double-blind clinical study examined the effects of rinsing with mouthwashes formulated with chlorhexidine [CHX], an ingredient widely utilized in the dental clinic in comparison to a control on oral PMN representing a novel measure of inflammation. A concurrent evaluation of dental plaque and gingival inflammation using widely accepted clinical indices was included in the study. The study enrolled adult subjects providing informed consent, met study criteria and registered gingival index scores of 1.0 or more at the screening visit. Subjects [n = 90; age range 19–58 years] completed a washout phase prior to baseline evaluations for PMN and clinical assessments for dental plaque and gingivitis. Treatments [CHX or a control mouthwash] were randomly assigned to subjects for twice-daily use for the next two weeks. Post-treatment evaluations similar to baseline were conducted after one and two week use of assigned treatment. Results: At baseline, no statistically significant differences between treatment groups for PMN or clinical indices for dental plaque or gingivitis were noted. Rinsing with CHX demonstrated significant reductions for PMN and dental plaque, gingivitis in comparison to the control group. After one and two week use of CHX, PMN demonstrated a 35.9% and 54.9% reduction respectively in comparison to the control group representing significant differences [p < 0.05]. At the one and two week post-treatment evaluations, rinsing with CHX demonstrated 15% and 25% reductions in gingivitis respectively and were significantly different from the control [p < 0.05]. Rinsing with CHX also demonstrated significant reductions in dental plaque of 15% and 19% at the one and two-week post-treatment evaluations respectively in comparison to the control [p < 0.05]. The CHX group also demonstrated reductions in interproximal scores and registered the lowest frequency of gingival index or dental plaque scores on all oral surfaces. Conclusions: Results outline an objective approach to evaluate oral inflammation demonstrating a large and sustained reduction in oral PMN by CHX with these outcomes numerically higher than a clinical index evaluating gingivitis.

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Enumeration of oral polymorphonuclear leukocytes [PMN] estimates the oral inflammatory burden.

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Rinsing with chlorhexidine demonstrated progressive PMN reductions corroborating gingivitis and dental plaque evaluations.

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Rapid PMN assessment provides objective assessment of treatment effects applicable for dental chair-side setting.

Exercise, Immunity, and Illness

It is generally accepted that moderate amounts of exercise improve immune system functions and hence reduce the risk of infection whereas athletes engaged in regular prolonged and/or intensive training have a higher than “normal” incidence of minor infections, especially of the upper respiratory tract (URT, e.g., common cold and influenza). This is likely related to regular acute (and possibly chronic) periods of exercise-induced changes in immune function. URT infections can compromise performance directly if suffered shortly before or during competition or indirectly if suffered at other times via effects on training and/or physiological adaptations. This chapter covers the effects of exercise (acute and chronic), both positive and negative, on immune function and consequent infection risk, and considers the current state-of-the-art for monitoring and assessing this in athletes.

Polymorphonuclear neutrophil integrity and functionality are preserved when exposed to saliva

OBJECTIVE

Polymorphonuclear neutrophils (PMNs) are the most abundant innate immune cells and are also important effectors in the maintenance of oral health. However, little is known about the effects of saliva on the PMN. We therefore aimed to investigate the effect of saliva on the PMNs' morphology and functioning.

DESIGN

Effect of saliva on the membrane integrity of PMNs isolated from blood was evaluated with FACS using Annexin V (apoptosis marker) and propidum iodide (membrane integrity marker). The effect on cell morphology was examined using transmission electron imaging. Binding and phagocytosis of the oral bacterium Fusobacterium nucleatum by PMNs was analysed by FACS. Reactive oxygen species (ROS) production was measured with chemiluminescence.

RESULTS

Incubation with saliva for 60 min had no detectable effects on the membrane integrity or the morphology of PMNs. In contrast, preincubation of F. nucleatum with saliva inhibited its subsequent interaction with PMNs, resulting in a diminished production of ROS.

CONCLUSIONS

Saliva does not impair the function of PMNs. However, interaction of salivary components with F. nucleatum may affect their recognition by PMNs resulting in a diminished functional response.

Oral polymorphonuclear neutrophil characteristics in relation to oral health: a cross-sectional, observational clinical study

Polymorphonuclear neutrophils (PMNs) have a major role in the innate immune system. However, little is known about PMN contribution in relation to oral health. The objective of this study was to investigate the numbers and functional characteristics of oral PMNs (oPMNs) compared with circulatory PMNs (cPMNs). Oral rinse and venous blood samples were obtained from 268 systemically and orally healthy volunteers in a cross-sectional observational study. PMN counts, cell cycle analysis and cellular activation state were investigated. Also, reactive oxygen species (ROS) production was analyzed, with and without bacterial stimulation (Fusobacterium nucleatum). In males, 1.2 × 10⁶±1.0 × 10⁶ oPMNs were collected, and showed a tendency to correlate with the levels of gingival bleeding (r=0.215, P=0.008). Comparable oPMNs counts were found among females (1.0 × 10⁶±0.7 × 10⁶). More late-stage apoptotic/necrotic cells were found among the oPMNs (53.1%) compared with the cPMNs (8.5% P<0.001). Without additional stimulation, oPMNs were more activated than cPMNs, as indicated by higher expression of CD11b, CD63 and CD66b, and higher constitutive ROS levels (P<0.001). Notably, in response to bacterial stimulation, oPMNs released comparable ROS levels as cPMNs (P=0.042). In conclusion, this study provides data on viable oPMNs showing high levels of activation in orally and systemically healthy individuals, free of apparent caries lesions and periodontal disease. These data suggests that although the oPMNs are in a more mature stage of their life cycle compared with the cPMNs, oPMNs are still responsive to stimulation, which indicates their functional potential and possible contribution to a healthy oral ecosystem.

Assessment of systemic inflammation with neutrophil-lymphocyte ratio in lichen planus

Introduction

Lichen planus (LP) is a papulosquamous eruption of the skin and mucous membranes. Although the exact pathogenesis of the disease remains unclear, it is believed that LP represents an inflammatory disorder. Neutrophil-lymphocyte (N/L) ratio is considered a systemic inflammatory marker that correlated with severity of the diseases.

Aim

To investigate whether N/L ratio increases in LP and may be an independent severity marker for LP lesions.

Material and methods

White blood cell (WBC), neutrophil and lymphocyte counts, N/L ratio, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were statistically compared between the patient (n = 55) and the control group (n = 48). The relationship of N/L ratio and the body surface area (BSA) was assessed.

Results

Erythrocyte sedimentation rate and CRP were statistically higher in patients with LP than in controls (p < 0.0001). Our analysis revealed a significantly higher level of N/L ratio in patients with LP compared with controls, respectively (2.5 ±1.1 (1.2–7.3) vs. 1.4 ±0.4 (0.8–2.7), p < 0.0001). Body surface area (p = 0.001), CRP (p = 0.006), and ESR (p = 0.003) were identified as possible predictors of N/L ratio, but only BSA (p = 0.002) and ESR (p = 0.003) were found as significant independent predictors in a multiple linear regression model.

Conclusions

The inflammatory process in LP was supported by our results. N/L ratio may have an impact to show the inflammatory status in patients with LP as an inexpensive, simple and effective predictor. It may be used for the severity and treatment option of LP. But, N/L ratio and LP relationship could be confirmed by other large prospective studies.

Oral neutrophil responses to acute prolonged exercise may not be representative of blood neutrophil responses

Neutrophil numbers and function (oxidative burst) were assessed in peripheral blood and oral samples before and after prolonged exercise. Blood neutrophil count increased (∼3.5-fold, P < 0.001) and function decreased (30% ± 19% decrease, P = 0.005) postexercise. Oral neutrophil count (P = 0.392) and function (P = 0.334) were unchanged. Agreement between oral and blood neutrophil function responses to exercise was poor. These findings highlight the importance of studying neutrophils within various compartments/sample types.

Dynamic interactions of neutrophils and biofilms

BACKGROUND

The majority of microbial infections in humans are biofilm-associated and difficult to treat, as biofilms are highly resistant to antimicrobial agents and protect themselves from external threats in various ways. Biofilms are tenaciously attached to surfaces and impede the ability of host defense molecules and cells to penetrate them. On the other hand, some biofilms are beneficial for the host and contain protective microorganisms. Microbes in biofilms express pathogen-associated molecular patterns and epitopes that can be recognized by innate immune cells and opsonins, leading to activation of neutrophils and other leukocytes. Neutrophils are part of the first line of defense and have multiple antimicrobial strategies allowing them to attack pathogenic biofilms.

OBJECTIVE/DESIGN

In this paper, interaction modes of neutrophils with biofilms are reviewed. Antimicrobial strategies of neutrophils and the counteractions of the biofilm communities, with special attention to oral biofilms, are presented. Moreover, possible adverse effects of neutrophil activity and their biofilm-promoting side effects are discussed.

RESULTS/CONCLUSION

Biofilms are partially, but not entirely, protected against neutrophil assault, which include the processes of phagocytosis, degranulation, and formation of neutrophil extracellular traps. However, virulence factors of microorganisms, microbial composition, and properties of the extracellular matrix determine whether a biofilm and subsequent microbial spread can be controlled by neutrophils and other host defense factors. Besides, neutrophils may inadvertently contribute to the physical and ecological stability of biofilms by promoting selection of more resistant strains. Moreover, neutrophil enzymes can degrade collagen and other proteins and, as a result, cause harm to the host tissues. These parameters could be crucial factors in the onset of periodontal inflammation and the subsequent tissue breakdown.

Assessment and comparison of phagocytic function and viability of polymorphonuclear leukocytes in saliva of smokers and non-smokers

OBJECTIVES

Tobacco use is one of the most important public health problems worldwide. It is also linked to impairment of normal immunologic surveillance and defence mechanism of polymorphonuclear leukocytes. Tobacco smoke and its components have been seen to affect the phagocytic ability and viability of polymorphonuclear leukocytes suggesting the pathogenesis of tobacco induced oral diseases. Aim of this study was to assess and compare the phagocytic function and viability of polymorphonuclear leukocytes in saliva of smokers and non smokers.

DESIGN

The study comprised of 35 smokers and 35 non-smokers, age matched. Saliva was collected by rinsing method and the polymorphonuclear leukocytes were separated. Phagocytic activity was determined by using latex spheres as targets. Cell viability was measured using trypan blue stain.

RESULTS

Salivary polymorphonuclear leukocytes in smokers showed significant reduction in the phagocytic activity by ingesting few latex spheres when compared to the non-smokers. The viability of these cells in saliva of smokers was significantly reduced.

CONCLUSIONS

The present study revealed reduced phagocytic activity and viability of salivary polymorphonuclear leukocytes in smokers compared to non-smokers. These findings indicate that smokers are more prone to gingival, periodontal and other oral diseases. Thus indicating that the health care professionals should encourage smoking cessation as an aid in preventing oral diseases.

Collection of in vivo transmigrated neutrophils from human skin

A wealth of knowledge on the life and death of human neutrophils has been obtained by the in vitro study of isolated cells derived from peripheral blood. However, neutrophils are of main importance, physiologically as well as pathologically, after they have left circulation and transmigrated to extravascular tissues. The journey from blood to tissue is complex and eventful, and tissue neutrophils are in many aspects distinct from the cells left in circulation. Here we describe how to obtain human tissue neutrophils in a controlled experimental setting from aseptic skin lesions created by the application of negative pressure. One protocol enables the direct analysis of the blister content, infiltrating leukocytes as well as exudate fluid, and is a simple method to follow multiple parameters of aseptic inflammation in vivo. Also described is the skin chamber technique, a method based on denuded skin blisters which are subsequently covered by collection chambers filled with autologous serum. Although slightly more artificial as compared to analysis of the blister content directly, the cellular yield of this skin chamber method is sufficient to perform a large number of functional analyses of in vivo transmigrated cells.

Activation pattern of neutrophils from blood of elderly individuals with Candida-related denture stomatitis

We have identified impaired neutrophils in elderly individuals which could be involved with Candida-related denture stomatitis (DS), an oral infection predominantly caused by Candida albicans, affecting especially elderly individuals using dental prosthesis. However, specific mechanisms performed by neutrophil contributing to the susceptibility of the elderly to DS are not fully understood. This study evaluated activation features of blood neutrophils from elderly and young individuals with DS. Blood neutrophils cultured with C. albicans from elderly subjects secreted decreased levels of CXCL8. However, C. albicans challenged-neutrophils from DS patients produced high IL-4 and IL-10, and low GM-CSF levels, regardless of age. Additional elastase activity of neutrophils from both elderly groups was detected after incubation with C. albicans, but only neutrophils from elderly DS demonstrated high myeloperoxidase activity. Therefore, DS patients have affected neutrophils, and the advance of age intensifies these damages. In summary, individuals with Candida-related denture stomatitis presented variation in the neutrophil phenotype and activation. Such alterations were more intense in neutrophils from infected elderly individuals.

Differences between salivary and blood neutrophils from elderly and young denture wearers

We previously showed that neutrophils from patients with Candida-related denture stomatitis exhibited damaged function, and the advance in age intensified this condition. Because such alterations had been determined in elderly people that were not denture wearers, the purpose of this study was to clarify functional and phenotypic characteristics of neutrophils from elderly denture wearers (EDW) and young denture wearers (YDW) without oral lesion. We enrolled 20 denture wearers (12 EDW and 8 YDW) and determined the positivity of Candida species on maxillary prosthesis and palate. Additionally, blood and salivary neutrophils were evaluated. Furthermore, cytokines and chemokines salivary levels were detected. YDW presented higher positivity of Candida albicans than elderly ones. However, blood neutrophils from EDW expressed less CXCR1, CD62L and CD11b and had lower C. albicans phagocytosis than YDW. Although myeloperoxidase and elastase activity was significantly higher in C. albicans-stimulated blood neutrophils from elderly, they produced high levels of IL-10 and low levels of Granulocyte macrophage-colony stimulating factor (GM-CSF). Despite apoptosis rate of salivary neutrophils was enhanced, these cells were at a high number in YDW. GM-CSF and IL10 were lower in saliva from elderly group. These data confirmed that ageing affects blood and salivary neutrophils and could predispose elderly to persistent oral infections.

Salivary neutrophils level as an indicator of bone marrow engraftment

AIM

The aim of this study was to investigate the neutrophils level in saliva as an adequate alternative to other methods for evaluating the neutrophil engraftment after autologous stem cell transplantation (ASCT) in hemato-oncology.

METHOD

A total of 35 patients treated for non-Hodgkin's lymphoma or multiple myeloma were stomatologically examined before planned high-dose chemotherapy with ASCT. After removal of potential foci of odontogenic infection all the patients underwent transplantation and during the treatment they were monitored for the level of neutrophils in saliva as a possible early indicator of the neutrophil engraftment. Neutrophil levels in saliva were compared to the neutrophil level in blood and to the degree of oral mucositis (the nurses study).

RESULTS

An increase of salivary neutrophils in the mouth rinse of > 25 x 10/\6/l was identified as an early sign of successful neutrophil engraftment that occurred 1 to 2 days before the rise of neutrophils in peripheral blood (> 0.5- x 10/\9/l).

CONCLUSIONS

Follow-up of neutrophil levels in saliva might be an adequate alternative to other methods for evaluating the neutrophil engraftment after ASCT in hemato-oncology.

Ageing exacerbates damage of systemic and salivary neutrophils from patients presenting Candida-related denture stomatitis

Background

Ageing leads to a decline in the function of the immune system, increasing the body's susceptibility to infections through the impairment of T-cells, macrophages, neutrophils and dendritic cells Denture stomatitis is a primary oral disease affecting elderly denture wearers. The major etiologic factor involved in this pathology is the infection by Candida albicans, an opportunistic pathogen that causes local and disseminated diseases in immunosuppressed humans. Neutrophils play a critical role in the immune response against C. albicans and are continually present in the salivary fluid and in the blood. The aim of this study was to determine ageing-related changes in salivary and blood neutrophils and their potential implications in Candida-related denture stomatitis.

Results

Our results showed a lower number of neutrophils in the saliva from patients presenting Candida-related denture stomatitis in comparison to their matched controls. Furthermore, fewer neutrophils were isolated from the saliva of aged control individuals in comparison to matched younger subjects. CXCR1, CD62L and CD11b expression were significantly greater on systemic neutrophils from younger control individuals. Elderly individuals showed more apoptotic salivary neutrophils and lower GM-CSF levels than younger ones, regardless of the occurrence of Candida infection. On the other hand, CXCL-8 concentrations were higher in the saliva from elderly individuals. Besides, TNF-α was detected at elevated levels in the saliva from infected elderly subjects. Salivary neutrophils from elderly and young patients presented impaired phagocytic activity against C. albicans. However, just systemic neutrophils from elderly showed decreased phagocytosis when compared to the younger ones, regardless of the occurrence of infection. In addition, neutrophils from aged individuals and young patients presented low fungicidal activity.

Conclusion

The data suggests that the Candida related-denture stomatitis is associated to neutrophils function deficiency, and ageing drastically appears to alter important characteristics of such cells, facilitating the establishment of this infection.

The levels of plasma and salivary antioxidants in the patient with recurrent aphthous stomatitis

BACKGROUND

Despite plenty of research, the cause of recurrent aphthous stomatitis (RAS) remains obscure. It has been proposed that, the aetiological factors such as local trauma, smoking, vitamin deficiencies and viral infections lead to aphthae formation via final common pathway based on increased oxidative stress. The aim of this investigation was to evaluate the antioxidant enzyme superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHPx) alterations in plasma and saliva, and in addition uric acid (UA) in saliva, in patients with RAS and healthy controls.

METHODS

Thirty-two patients with RAS and 30 healthy controls were included into the study. The SOD, CAT, GSHPx and UA levels were measured in plasma and saliva in study and control groups.

RESULTS

In the RAS group, although the mean SOD (P<0.001) and CAT (P<0.05) levels of plasma were lower, GSHPx (P<0.001) levels were higher than control group. The salivary concentrations of the SOD (P<0.001), CAT (P<0.05) and GSHPx (P<0.001) in RAS group were entirely opposite to plasma concentrations. UA were not significant between RAS group and controls.

CONCLUSION

Since we found salivary SOD and CAT levels were high whereas plasma levels were low, it has been thought that, salivary defence mechanisms via antioxidant agents may be stimulated against to the ulcerous lesion. We consider that the organism might mobilize the antioxidant potential to the sites where they were needed. At this point, decrease of SOD and CAT levels in the plasma may be related to this shift. It is also thought that GSHPx secretion in the saliva may also be increased but the increase in its turnover may be responsible for the diminished activity.