Plasma IL-8 signature correlates with pain and depressive symptomatology in patients with burning mouth syndrome: Results from a pilot study

Non-neuronal cells act as crucial players in neuropathic orofacial pain

BACKGROUND

Following peripheral nerve damage, various non-neuronal cells are activated, triggering accumulation in the peripheral and central nervous systems, and communicate with neurons. Evidence suggest that neuronal and non-neuronal cell communication is a critical mechanism of neuropathic pain; however, its detailed mechanisms in contributing to neuropathic orofacial pain development remain unclear.

HIGHLIGHT

Neuronal and non-neuronal cell communication in the trigeminal ganglion (TG) is believed to cause neuronal hyperactivation following trigeminal nerve damage, resulting in neuropathic orofacial pain. Trigeminal nerve damage activates and accumulates non-neuronal cells, such as satellite cells and macrophages in the TG and microglia, astrocytes, and oligodendrocytes in the trigeminal spinal subnucleus caudalis (Vc) and upper cervical spinal cord (C1-C2). These non-neuronal cells release various molecules, contributing to the hyperactivation of TG, Vc, and C1-C2 nociceptive neurons. These hyperactive nociceptive neurons release molecules that enhance non-neuronal cell activation. This neuron and non-neuronal cell crosstalk causes hyperactivation of nociceptive neurons in the TG, Vc, and C1-C2. Here, we addressed previous and recent data on the contribution of neuronal and non-neuronal cell communication and its involvement in neuropathic orofacial pain development.

CONCLUSION

Previous and recent data suggest that neuronal and non-neuronal cell communication in the TG, Vc, and C1-C2 is a key mechanism that causes neuropathic orofacial pain associated with trigeminal nerve damage.

Burning Mouth Syndrome Treated with Low-Level Laser and Clonazepam: A Randomized, Single-Blind Clinical Trial

OBJECTIVE

Burning mouth syndrome (BMS) is a chronic pain disorder characterized by intraoral burning or dysaesthetic sensation, with the absence of any identifiable lesions. Numerous treatments for BMS have been investigated, though without conclusive results. An analysis was conducted of the efficacy of treatment with a low-level diode laser and clonazepam in patients with BMS, and a study was carried out on the levels of different salivary biomarkers before and after treatment.

MATERIAL AND METHODS

A randomized, single-blind clinical trial was carried out involving 89 patients divided into the following groups: group 1 (laser, The Helbo® Theralite Laser 3D Pocket Probe + clonazepam) (n = 20), group 2 (sham laser placebo) (n = 19), group 3 (laser) (n = 21) and group 4 (clonazepam) (n = 18). Symptom intensity was scored based on a visual analogue scale (VAS). Sialometry was performed before and after treatment, and the Xerostomia Inventory, Oral Health Impact Profile-14 (OHIP-14) and Mini-Nutritional Assessment (MNA) questionnaires were administered. The following markers were measured in saliva samples: interleukins (IL2, IL4, IL5, IL6, IL7, IL8, IL1β, IL10, IL12, IL13, IL17, IL21 and IL23), proteins (MIP-3α, MIP-1α and MIP-1β), GM-CSF, interferon gamma (IFNγ), interferon-inducible T-cell alpha chemoattractant (ITAC), fractalkine and tumor necrosis factor α (TNFα).

RESULTS

A significant decrease in the VAS scores was observed after treatment in group 1 (laser + clonazepam) (p = 0.029) and group 3 (laser) (p = 0.005). In turn, group 3 (laser) showed a decrease in the salivary concentration of fractalkine (p = 0.025); interleukins IL12 (p = 0.048), IL17 (p = 0.020), IL21 (p = 0.008), IL7 (p = 0.001) and IL8 (p = 0.007); proteins MIP1α (p = 0.048) and MIP1β (p = 0.047); and TNFα (p = 0.047) versus baseline. Following treatment, group 1 (laser + clonazepam) showed significant differences in IL21 (p = 0.045) and IL7 (p = 0.009) versus baseline, while group 4 (clonazepam) showed significant differences in IL13 (p = 0.036), IL2 (p = 0.020) and IL4 (p = 0.001). No significant differences were recorded in group 2 (sham laser placebo).

CONCLUSIONS

The low-level diode laser is a good treatment option in BMS, resulting in a decrease in patient symptoms and in salivary biomarkers. However, standardization of the intervention protocols and laser intensity parameters is needed in order to draw more firm conclusions.

Potential salivary and serum biomarkers for burning mouth syndrome and their relationship with anxiety/depression

Background/purpose

The pathophysiology of burning mouth syndrome (BMS), although considered a multifactorial etiology including psychological factors, is still not well understood. Hence, this study aimed to investigate the potential usage of salivary and serum biomarkers, including brain-derived neurotrophic factor (BDNF), interferon-gamma (IFN-γ), interleukin-1beta (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-alpha (TNF-α), in diagnosing BMS and their correlations with anxiety/depression.

Materials and methods

45 BMS patients and 14 healthy volunteers were enrolled. The patients were divided into BMS with anxiety/depression group and BMS without anxiety/depression group according to the scores of the Zung Self-rating Anxiety Scale (SAS) and Zung Self-rating Depression Scale (SDS). Additionally, concentrations of BDNF, IFN-γ, IL-1β, IL-6, IL-8, and TNF-α in saliva and those in serum among the patients and healthy volunteers were assessed by multiplex assay using Luminex 200TM system and Enzyme-linked immunosorbent assay (ELISA), respectively.

Results

Among all the serum biomarkers, only BDNF showed a statistically significant decrease in the patients than the healthy volunteers (P < 0.05). Regarding saliva biomarkers, BDNF, IL-1β, and IL-8 all exhibited a statistically significant increase in all the BMS patients versus the healthy volunteers (P < 0.05) but only BDNF was significantly different between patients with anxiety/depression and healthy individuals when considering anxiety/depression. Among BMS patients with anxiety/depression, saliva TNF-α had positive associations with other biomarkers including BDNF, IFN-γ, IL-1β, IL-6, and IL-8 (P < 0.05).

Conclusion

The increased concentration of saliva BDNF holds strong potential for diagnosing BMS and the elevated level of saliva TNF-α is crucial in identifying BMS patients with anxiety/depression.

Salivary and serum biomarkers to evaluate psychological disorders in burning mouth syndrome: A systematic review and meta-analysis

BACKGROUND

Burning mouth syndrome is a chronic pain syndrome mainly characterized by an intensive burning sensation of tongue. Previous studies have suggested that saliva/serum biomarkers in burning mouth syndrome might be associated with psychological disorders. The aim of systematic review was to observe whether the biomarkers in serum/saliva could be an alternative method to evaluate the psychological disorders in patients with burning mouth syndrome.

MATERIALS AND METHODS

The PubMed, Embase, and Cochrane Library databases were searched for papers published up to March 15, 2023. Risk of bias was measured by using the Newcastle-Ottawa Scale. RevMan was used for meta-analysis.

RESULTS

A total of 467 articles were screened, which of 12 studies were included. These studies collected 43 different biomarkers in saliva and 35 in serum. Of these biomarkers, only three (cortisol, α-amylase, and IL-6) were analyzed in two or more studies. Only salivary cortisol levels were significantly higher in the patient group compared to the controls (Mean Difference = 1.39; 95% CI [0.80-1.97]; p < 0.001). Moreover, cortisol might be relevant to psychological scores, especially anxiety.

CONCLUSION

Different papers have investigated salivary and serum biomarkers in burning mouth syndrome patients with controversial results. This meta-analysis showed that cortisol levels in saliva may be a potential biomarker to assess the psychological disorders in burning mouth syndrome patients.

Is burning mouth syndrome associated with stress? A meta-analysis

BACKGROUND

Some studies have shown burning mouth syndrome (BMS) as comorbid psychosocial and psychiatric disorders, and as well, pointed at stress as a major risk factor.

OBJECTIVE

The aim of this meta-analysis was to answer the following question: 'Is there an association between BMS and stress, compared to healthy controls?'

METHODS

Two reviewers searched for the effect of stress in BMS and published on five main databases and three from the grey literature. Various questionnaires and biomarkers were analysed. Of the 2489 selected articles, 30 met the inclusion criteria. Studies englobed questionnaires, such as Perceived Stress Questionnaire, Lipp Stress Symptoms Inventory, Holmes-Rahe scale, Depression, Anxiety, and Stress Scale (DASS-21), Recent Experience Test; and various biomarkers, such as cortisol, opiorphin, IgA, α-amylase and interleukins.

RESULTS

In all studies with questionnaires, stress was significantly increased in the BMS group vs. control. Patients with BMS presented 25.73% higher cortisol levels, 28.17% higher IgA levels and 40.62% higher α-amylase levels than controls. Meta-analysis found that BMS subjects presented 3.01 nmoL/L [0.53; 5.50] higher cortisol levels, 84.35 kU/L [15.00; 153.71] higher α-amylase levels, 29.25 mg/mL [9.86; 48.64] higher IgA levels and 258.59 pg/mL [59.24; 457.94] higher IL-8 levels than control. No differences were found for opiorphin concentration in ng/mL [-0.96; 2.53]. For interleukins, no differences were founded for IL-1 β, IL-2, IL-4, IL-6, IL-8, IL-10 and TNF-α.

CONCLUSION

Based on the available evidence, this meta-analysis suggests more stress factors in questionnaire-based studies, and higher levels of cortisol, α-amylase, IgA and IL-8 biomarkers in BMS subjects than controls.

Effects of low-level laser therapy on burning pain and quality of life in patients with burning mouth syndrome: a systematic review and meta-analysis

BACKGROUND

Burning mouth syndrome (BMS) is a complex chronic pain disorder that significantly impairs patients' quality of life. Low-level laser therapy (LLLT) uses infrared or near-infrared light to produce analgesic, anti-inflammatory, and biological stimulation effects. The aim of this systematic review is to evaluate the effect of LLLT on burning pain, quality of life, and negative emotions in patients with BMS.

METHODS

The PubMed, Embase, Cumulative Index of Nursing and Allied Health Literature (CINAHL), Cochrane Library, Web of Science, and Scopus databases were searched up January 2023 to identify relevant articles. All randomized controlled trials that were published in English and examined the use of LLLT treatment for BMS were included. The methodological quality of the included trials was assessed using the Cochrane risk of bias tool for randomized controlled trials (RCTs). A meta-analysis was performed to evaluate burning pain, quality of life, and negative emotions. Sensitivity, subgroup, and funnel plot analyses were also carried out.

RESULTS

Fourteen RCTs involving a total of 550 patients with BMS met the inclusion criteria. The results showed that LLLT (measured by the Visual Analog Scale; SMD: -0.87, 95% CI: -1.29 to -0.45, P < 0.001) was more effective for reducing burning pain than placebo LLLT or clonazepam. LLLT improved quality of life (evaluated by the Oral Health Impact Profile-14; SMD: 0.01, 95% CI: -0.58 to 0.60, P = 0.97) and negative emotions (evaluated by the Hospital Anxiety and Depression Scale; SMD: -0.12, 95% CI: -0.54 to 0.30, P = 0.59), but these effects were not statistically significant.

CONCLUSIONS

The meta-analysis revealed that LLLT may be an effective therapy for improving burning pain in patients with BMS, and producing a positive influence on quality of life and negative emotions. A long-term course of intervention, a larger sample size, and a multidisciplinary intervention design are urgently needed in future research.

TRIAL REGISTRATION

PROSPERO registration number: CRD42022308770.

Cytokine expression profiles in white blood cells of patients with small fiber neuropathy

BACKGROUND

The role of cytokines in the pathophysiology, diagnosis, and prognosis of small fiber neuropathy (SFN) is incompletely understood. We studied expression profiles of selected pro- and anti-inflammatory cytokines in RNA from white blood cells (WBC) of patients with a medical history and a clinical phenotype suggestive for SFN and compared data with healthy controls.

METHODS

We prospectively recruited 52 patients and 21 age- and sex-matched healthy controls. Study participants were characterized in detail and underwent complete neurological examination. Venous blood was drawn for routine and extended laboratory tests, and for WBC isolation. Systemic RNA expression profiles of the pro-inflammatory cytokines interleukin (IL)-1ß, IL-2, IL-8, tumor necrosis factor-alpha (TNF) and the anti-inflammatory cytokines IL-4, IL-10, transforming growth factor beta-1 (TGF) were analyzed. Protein levels of IL-2, IL-8, and TNF were measured in serum of patients and controls. Receiver operating characteristic (ROC)-curve analysis was used to determine the accuracy of IL-2, IL-8, and TNF in differentiating patients and controls. To compare the potential discriminatory efficacy of single versus combined cytokines, equality of different AUCs was tested.

RESULTS

WBC gene expression of IL-2, IL-8, and TNF was higher in patients compared to healthy controls (IL-2: p = 0.02; IL-8: p = 0.009; TNF: p = 0.03) and discriminated between the groups (area under the curve (AUC) ≥ 0.68 for each cytokine) with highest diagnostic accuracy reached by combining the three cytokines (AUC = 0.81, sensitivity = 70%, specificity = 86%). Subgroup analysis revealed the following differences: IL-8 and TNF gene expression levels were higher in female patients compared to female controls (IL-8: p = 0.01; TNF: p = 0.03). The combination of TNF with IL-2 and TNF with IL-2 and IL-8 discriminated best between the study groups. IL-2 was higher expressed in patients with moderate pain compared to those with severe pain (p = 0.02). Patients with acral pain showed higher IL-10 gene expression compared to patients with generalized pain (p = 0.004). We further found a negative correlation between the relative gene expression of IL-2 and current pain intensity (p = 0.02). Serum protein levels of IL-2, IL-8, and TNF did not differ between patients and controls.

CONCLUSIONS

We identified higher systemic gene expression of IL-2, IL-8, and TNF in SFN patients than in controls, which may be of potential relevance for diagnostics and patient stratification.

Evaluation of serum neuron specific enolase levels among patients with primary and secondary burning mouth syndrome

INTRODUCTION

Burning mouth syndrome is a painful condition of the oral cavity with ambiguous pathogenesis and diagnosis. Neuron-specific enolase is increased in several conditions including peripheral neuropathy of diabetes, ophthalmopathies, spinal cord injuries and tumors. Evidence on association of burning mouth syndrome and neuron-specific enolase is limited.

AIM

This study aims to evaluate neuron-specific enolase levels in primary and secondary burning mouth syndrome patients and compare the levels of neuron-specific enolase with associated conditions in secondary burning mouth syndrome.

METHODS

One hundred and twenty-eight patients of more than 18 years of age with no gender predilection and having clinical symptoms of burning mouth syndrome and 135 healthy subjects were included. All the patients fulfilled Scala's criteria for the diagnosis of burning mouth syndrome, including "primary" (idiopathic) and "secondary" (resulting from identified precipitating factors) burning mouth syndrome patients. Blood samples were obtained from burning mouth syndrome patients. Serum neuron-specific enolase was evaluated using enzyme-linked immunosorbent assay. To compare means and standard deviations, among primary and secondary burning mouth syndrome, data was analysed with analysis of variance and multiple comparisons test.

RESULTS

The mean age of the study participants for burning mouth syndrome and healthy subjects was 53.30 and 51.6 years, respectively. Amongst the secondary burning mouth syndrome group, 32 (25%) of the patients had menopause, 15 (11.7%) had diabetes, eight (6.2%) of the patients had nutritional deficiency, seven (5.4%) had combined diabetes, menopause, and depression, six (4.6%) had combined diabetes and depression, four (3.1%) were diagnosed with Sjögren's syndrome. A minor percentage of 2.3% (three) had gastroesophageal reflux disease, while the remaining three (2.3%) patients in the secondary burning mouth syndrome group were on anti-depressants. There was a statistically significant increase in the levels of neuron-specific enolase in primary burning mouth syndrome as compared to the secondary burning mouth syndrome and healthy groups. Among the subgroups of secondary burning mouth syndrome, diabetic individuals showed a significant increase in neuron-specific enolase level when compared with other conditions in the secondary burning mouth syndrome patients.Discussion and conclusion: The raised serum neuron-specific enolase levels in patients suffering from primary burning mouth syndrome highlight a possible neuropathic mechanism. It was also increased in the sub-group of secondary burning mouth syndrome patients having diabetes. Although it cannot be ascertained whether the deranged values in the diabetic group were due to burning mouth syndrome or due to diabetes, the raised quantity of neuron-specific enolase in the primary burning mouth syndrome group is a reliable diagnostic indicator. Future studies on the assessment of neuron-specific enolase levels as a diagnostic tool for onset and management of primary and secondary burning mouth syndrome are recommended.

Burning Fog: Cognitive Impairment in Burning Mouth Syndrome

Background: Due to its common association with chronic pain experience, cognitive impairment (CI) has never been evaluated in patients with burning mouth syndrome (BMS). The purpose of this study is to assess the prevalence of CI in patients with BMS and to evaluate its relationship with potential predictors such as pain, mood disorders, blood biomarkers, and white matter changes (WMCs).

Methods: A case-control study was conducted by enrolling 40 patients with BMS and an equal number of healthy controls matched for age, gender, and education. Neurocognitive assessment [Mini Mental State Examination (MMSE), Digit Cancellation Test (DCT), the Forward and Backward Digit Span task (FDS and BDS), Corsi Block-Tapping Test (CB-TT), Rey Auditory Verbal Learning Test (RAVLT), Copying Geometric Drawings (CGD), Frontal Assessment Battery (FAB), and Trail Making A and B (TMT-A and TMT-B)], psychological assessment [Hamilton Rating Scale for Depression and Anxiety (HAM-D and HAM-A), Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), and 36-Item Short Form Health Survey (SF-36)], and pain assessment [Visual Analogic Scale (VAS), Total Pain Rating index (T-PRI), Brief Pain Inventory (BPI), and Pain DETECT Questionnaire (PD-Q)] were performed. In addition, blood biomarkers and MRI of the brain were recorded for the detection of Age-Related WMCs (ARWMCs). Descriptive statistics, the Mann-Whitney U-test, the Pearson Chi-Squared test and Spearman's correlation analysis were used.

Results: Patients with BMS had impairments in most cognitive domains compared with controls (p < 0.001^**) except in RAVLT and CGD. The HAM-D, HAM-A, PSQI, ESS, SF-36, VAS, T-PRI, BPI and PD-Q scores were statistically different between BMS patients and controls (p < 0.001^**) the WMCs frequency and ARWMC scores in the right temporal (RT) and left temporal (LT) lobe were higher in patients with BMS (p = 0.023^*).

Conclusions: Meanwhile, BMS is associated with a higher decline in cognitive functions, particularly attention, working memory, and executive functions, but other functions such as praxis-constructive skills and verbal memory are preserved. The early identification of CI and associated factors may help clinicians to identify patients at risk of developing time-based neurodegenerative disorders, such as Alzheimer's disease (AD) and vascular dementia (VD), for planning the early, comprehensive, and multidisciplinary assessment and treatment.

Neuropathic and Psychogenic Components of Burning Mouth Syndrome: A Systematic Review

The pathophysiology of primary burning mouth syndrome (BMS) has been extensively debated but is poorly understood despite a large number of hypotheses attempting to explain its etiopathogenic mechanisms. The aim of the present work was to systematically review papers that could provide arguments in favour of the neuropathic and psychogenic components of primary BMS for a better understanding of the disease. This systematic review (SR) was registered in PROSPERO (CRD42021224160). The search was limited to articles in English or French from 1990 to 01 December 2020. A total of 113 articles were considered for data extraction. We divided them into four subgroups: pharmacological and nonpharmacological management studies (n = 23); neurophysiological studies (n = 35); biohistopathological studies (n = 25); and questionnaire-based studies (n = 30). Several of these studies have shown neuropathic involvement at various levels of the neuraxis in BMS with the contribution of quantitative sensory testing (QST), functional brain imaging, and biohistopathological or pharmacologic studies. On the other hand, the role of psychological factors in BMS has also been the focus of several studies and has shown a link with psychiatric disorders such as anxiety and/or depression symptoms. Depending on the patient, the neuropathic and psychogenic components may exist simultaneously, with a preponderance of one or the other, or exist individually. These two components cannot be dissociated to define BMS. Consequently, BMS may be considered nociplastic pain.

Differential impact of keratinocytes and fibroblasts on nociceptor degeneration and sensitization in small fiber neuropathy

ABSTRACT

Peripheral denervation and pain are hallmarks of small fiber neuropathy (SFN). We investigated the contribution of skin cells on nociceptor degeneration and sensitization. We recruited 56 patients with SFN and 31 healthy controls and collected skin punch biopsies for immunohistochemical and immunocytochemical analysis of netrin-1 (NTN1) and proinflammatory and anti-inflammatory cytokine expression patterns. We further applied coculture systems with murine dorsal root ganglion (DRG) neurons for skin cell-nerve interaction studies and patch-clamp analysis. Human keratinocytes attract murine DRG neuron neurites, and the gene expression of the axon guidance cue NTN1 is higher in keratinocytes of patients with SFN than in controls. NTN1 slows and reduces murine sensory neurite outgrowth in vitro, but does not alter keratinocyte cytokine expression. In the naive state, keratinocytes of patients with SFN show a higher expression of transforming growth factor-β1 (P < 0.05), while fibroblasts display higher expression of the algesic cytokines interleukin (IL)-6 (P < 0.01) and IL-8 (P < 0.05). IL-6 incubation of murine DRG neurons leads to an increase in action potential firing rates compared with baseline (P < 0.01). Our data provide evidence for a differential effect of keratinocytes and fibroblasts on nociceptor degeneration and sensitization in SFN compared with healthy controls and further supports the concept of cutaneous nociception.

Role of interleukin 8 in depression and other psychiatric disorders

Low grade neuroinflammation has been suggested as one of the underlying mechanisms of many psychiatric diseases as well as cognitive disorders. Interleukin 8 (IL-8), a proinflammatory cytokine produced by many cell types including macrophage and microglia, mainly functions as a neutrophil chemoattractant in the bloodstream. IL-8 is also found in the brain, where it is released from microglia in response to proinflammatory stimuli. In this review, we highlight studies focusing on the role of IL-8 in psychiatric diseases such as major depression, bipolar disorder, schizophrenia, sleep disorder, autism spectrum disorder, anxiety disorders and dementia. Increased peripheral IL-8 levels have been reported in these diseases, particularly in schizophrenic disorder, bipolar disorder, obstructive sleep apnea and autism spectrum disorder. The literature on IL-8 and major depression is inconsistent. IL-8 has been found to be a factor associated with schizophrenic prognosis and therapeutic response, and may affect a wide range of symptomatology. Considering that the exact role of immune alterations is still under research, the success of immune-based therapies in psychiatric diseases is limited for the time being.

Efficacy of the laser at low intensity on primary burning oral syndrome: a systematic review

BACKGROUND

Primary burning mouth syndrome (BMS) is a chronic clinical condition of idiopathic mainly characterized by pain and a burning sensation in the oral cavity. The application of laser at low intensity therapy is a treatment option. This systematic review evaluated the efficacy of laser therapy in treating symptoms of burning mouth syndrome.

MATERIAL AND METHODS

The study was formulated according to the PRISMA and Cochrane guidelines. Seven databases were used as primary sources of research. Only randomized controlled clinical trials were included. The efficacy of the therapy was estimated comparing the values of the visual and numerical scales of pain before and after laser treatment, through qualitative analysis.

RESULTS

The search resulted in 348 records and only eight filled the eligibility criteria and were included. All studies evaluated pain and / or a burning sensation considering a time interval of two to ten weeks. The total sample consisted of 314 patients submitted to treatment: 123 from the control group, who participated with laser off or with the tip blocked, and 191 from the intervention group, treated with low-level laser therapy. The female gender stood out and the average age of the participants was 60.89 years. The main symptoms reported were pain and a burning sensation in the oral mucosa and tongue. The parameters adopted by the authors for laser treatment were diverse and the variables were not fully described in the published studies. Visual analog and numerical scales were used to assess symptoms and only three studies showed statistical significance.

CONCLUSIONS

It is suggested that laser therapy may be an effective alternative in the treatment of BMS. New randomized clinical trials should consider well-established protocols to better understand the efficacy of laser therapy without confounding the effects.

Vortioxetine in the Treatment of Mood Disorders Associated with Burning Mouth Syndrome: Results of an Open-Label, Flexible-Dose Pilot Study

OBJECTIVE

To evaluate the efficacy of a new multimodal antidepressant, vortioxetine (VO), in the management of burning mouth syndrome (BMS).

DESIGN

Longitudinal single-assessment open-label pilot study.

SETTING

University hospital. Subjects. Thirty BMS patients were enrolled.

METHODS

BMS patients were treated with topical clonazepam and a flexible dose of VO (10 mg, 15 mg, or 20 mg). The visual analog scale (VAS), the Total Pain Rating Index (T-PRI), the Hamilton Rating Scales for Depression (HAM-D) and Anxiety (HAM-A), and the Pittsburgh Sleep Quality Index (PSQI) were performed at baseline (time 0) and after two (time 1), four (time 2), six (time 3), and 12 months (time 4) of treatment. Descriptive statistics and the Wilcoxon nonparametric test for two paired samples were used.

RESULTS

The BMS patients showed a statistically significant improvement in VAS and T-PRI scores from baseline (median [interquartile range {IQR}] = 10.0 [10-10] and 22.0 [20-24], respectively) to time 4 (median [IQR] = 0.0 [0-0] and 8.0 [7-9], P < 0.001, respectively). Similarly, the HAM-A and HAM-D and PSQI scores showed an improvement from time 0 (median [IQR] = 20 [15.8-22], 19 [16-20.3], and 4.0 [4-7.3], respectively) to time 4 (median [IQR] = 6.0 [6-7], 6.0 [6-7], and 3.0 [3-4], respectively, P < 0.001).

CONCLUSIONS

VO is efficacious and well tolerated in the treatment of BMS in firstline therapy on account of its better receptor pharmacological profile and in second-line treatment for patients who have only partially responded or have reported adverse effects to previous treatments.

Vortioxetine versus other antidepressants in the treatment of burning mouth syndrome: An open-label randomized trial

OBJECTIVES

This randomized open-label trial compared the efficacy and tolerability of vortioxetine (15 mg/daily) with different antidepressants in the treatment of patients with burning mouth syndrome (BMS).

METHODS

One and hundred fifty BMS patients were randomized into five groups and treated with either vortioxetine, paroxetine (20 mg/daily), sertraline (50 mg/daily), escitalopram (10 mg/daily) or duloxetine (60 mg/daily). The Visual Analogue Scale (VAS), Total Pain Rating Index (T-PRI), Hamilton Rating Scales for Depression (HAM-D) and Anxiety (HAM-A), and Clinical Global Impression Improvement (CGI-I) and Efficacy scales (CGI-E) were performed at baseline and after 2, 4, 6, and 12 months of treatment. Any adverse events (AEs) were tabulated for each group. Descriptive statistics, including the Kruskal-Wallis non-parametric test and the Friedman non-parametric test for median comparisons between different times, were used.

RESULTS

All the antidepressants (AD) were associated with a significant decrease in the VAS, T-PRI, HAM-A, HAM-D, CGI-I, and CGI-E scores in the long-term (p < .001). However, the response rate of the vortioxetine group showed a significant reduction after six months. The medians, after 6 months, were as follows: VAS 0.0; T-PRI 2.0; HAM-A 7.0; HAM-D 7.0; CGI-I 1.0; and CGI-E 1.0 with a lower incidence of AEs (p < .019).

CONCLUSION

Vortioxetine was efficacious with a shorter latency of action and fewer AEs compared with other ADs.

Kynurenine, Tetrahydrobiopterin, and Cytokine Inflammatory Biomarkers in Individuals Affected by Diabetic Neuropathic Pain

Neuropathic pain is a common complication of diabetes with high morbidity and poor treatment outcomes. Accumulating evidence suggests the immune system is involved in the development of diabetic neuropathy, whilst neuro-immune interactions involving the kynurenine (KYN) and tetrahydrobiopterin (BH4) pathways have been linked to neuropathic pain pre-clinically and in several chronic pain conditions. Here, using a multiplex assay, we quantified serum levels of 14 cytokines in 21 participants with type 1 diabetes mellitus, 13 of which were classified as having neuropathic pain. In addition, using high performance liquid chromatography and gas chromatography-mass spectrometry, all major KYN and BH4 pathway metabolites were quantified in serum from the same cohort. Our results show increases in GM-CSF and IL-8, suggesting immune cell involvement. We demonstrated increases in two inflammatory biomarkers: neopterin and the KYN/TRP ratio, a marker of indoleamine 2,3-dioxygenase activity. Moreover, the KYN/TRP ratio positively correlated with pain intensity. Total kynurenine aminotransferase activity was also higher in the diabetic neuropathic pain group, indicating there may be increased production of the KYN metabolite, xanthurenic acid. Overall, this study supports the idea that inflammatory activation of the KYN and BH4 pathways occurs due to elevated inflammatory cytokines, which might be involved in the pathogenesis of neuropathic pain in type 1 diabetes mellitus. Further studies should be carried out to investigate the role of KYN and BH4 pathways, which could strengthen the case for therapeutically targeting them in neuropathic pain conditions.

Differential Transcription of Selected Cytokine and Neuroactive Ligand-receptor Genes in Peripheral Leukocytes from Calves in Response to Cautery Disbudding

Simple Summary

Calf disbudding is a painful husbandry practice on dairy and beef cattle farms. Continuing efforts to enhance the accuracy of pain assessment can aid in the application of effective anti-nociceptive (analgesic) agents in non-verbal animals. The aim of this study was to evaluate the changes in the expression of genes involved in inflammation and pain sensitisation in response to removal of horn buds in calves, using hot-iron cauterization. The efficacy of an analgesic, meloxicam, was also tested in attenuating the changes in expression of the studied genes post-disbudding. It was revealed that cautery disbudding induces significant changes in the expression of genes involved in inflammation. Meloxicam was able to blunt the increased expression of some of the genes at 4 h and 24 h after disbudding, while it could not attenuate the increased expression of a few other genes associated with inflammation.

Abstract

Calf disbudding is a painful husbandry practice on dairy and beef cattle farms. An objective measurement of pain is useful to reliably evaluate the pain intensity and anti-nociceptive (analgesic) efficacy of therapeutic agents. The aim of this study was to investigate the changes in peripheral leucocyte inflammatory cytokine gene expression in calves after disbudding, and to assess whether the changes in cytokine gene expression could be an indicator of the efficacy of analgesic drugs. In a randomised controlled study, 16 calves (aged 31 to 41 days and weighing 58 to 73 kg), undergoing routine disbudding, were randomly allocated into two groups (n = 8 in each group). Calves in the control group received no analgesic, while those in the treatment group received 0.5 mg kg⁻¹ meloxicam subcutaneously prior to disbudding. Disbudding was performed using an electric debudder. Blood (10 mL) was sampled from the jugular vein just before and 4 and 24 h post-disbudding, RNA was extracted from leukocytes, and the transcription of 12 genes of interest was assessed using nCounter gene expression assay. The results showed significantly higher transcription (compared to baseline values) of the studied genes (except CRH, IFNγ, and IL10) in the control group calves at either 4 or 24 h post-disbudding. The administration of meloxicam one hour before disbudding significantly attenuated the upregulation of IL6, PGHS2, TAC1, NOS1, and CRH gene transcription post-disbudding, while it did not suppress the elevated transcription of acute and pro-inflammatory cytokines such as IL1β, IFNγ, IL8, and TNFα genes. In conclusion, nCounter gene expression assay seems to be a promising tool to study the expression of cytokine genes and thus could be used for the pre-clinical evaluation of novel analgesics.

Evaluation of IL-6 levels and +3954 polymorphism of IL-1β in burning mouth syndrome: A systematic review and meta-analysis

This study evaluated IL-6 salivary levels as well as the +3954 polymorphism of IL-1β in patients with burning mouth syndrome and healthy individuals, through case-control studies. This systematic review and meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We conducted this research in PubMed/MEDLINE, Cochrane Library and Web of Science databases. The risk of bias was measured based in the Newcastle-Ottawa Scale. Researches with a group of patients with burning mouth syndrome and a control group in which the presence of the +3954 polymorphism of IL-1β and/ or IL-6 salivary levels through non-stimulated saliva were evaluated to detect if this interleukin concentrations are increased in patients and if the polymorphism is a risk factor for this syndrome. We identified seven studies with total of 440 participants, 229 patients with burning mouth syndrome and 211 healthy controls, ages 24-84 years old. The female gender was predominant. Patients in the majority of studies did not present increased levels of IL-6 and the +3954 polymorphism of IL-1β is not a risk factor for this syndrome. A few studies researched biomarkers in this pathology and more investigations are required not only to identify salivary levels and the polymorphism evaluated, but also other interleukins and polymorphisms in order to clarify the etiopathogenesis of this syndrome as well as for propose new diagnostic methods and treatments.

Adjunctive effects of laser therapy on somatosensory function and vasomotor regulation of periodontal tissues in patients with periodontitis: A randomized controlled clinical trial

BACKGROUND

The purpose of this prospective study was to compare the changes in periodontal somatosensory function and microcirculation in patients with periodontitis following initial treatment with scaling and root planing (SRP) with or without adjuvant laser therapy.

METHODS

Twenty-four patients suffering from periodontitis were recruited and randomly allocated into a split-mouth design to either SRP combined laser therapy side (test side) or SRP only side (control side). All treatments were performed by the same investigator at a single visit. Laser Doppler Flowmetry (LDF) and Quantitative Sensory Testing (QST) were performed at baseline (W0), 1 week (1W), 2 weeks (2W), and 4 weeks (4W) after treatment on both sides of the attached gingiva of the maxillary lateral incisor. Clinical examination including probing depth (PD) and bleeding on probing (BOP) was performed at W0, 2W, and 4W on both sides. Data were analyzed with two-way analysis of variance.

RESULTS

PD and BOP significantly improved after treatment (P <0.001). LDF values were significantly decreased on both sides at all follow-up time points (P <0.001), temperature was increased only on the test side (P = 0.017) whereas there was no significant change on the control side (P = 0.792). Significantly less sensitivity was observed for all QST parameters (P <0.030) except for warmth detection after treatment.

CONCLUSION

Adjunctive use of laser therapy did not provide any significant clinical advantage or additional effects on the recovery of periodontal somatosensory function or gingival microcirculation in the present study.

Neuraxial Cytokines in Pain States

A high-intensity potentially tissue-injuring stimulus generates a homotopic response to escape the stimulus and is associated with an affective phenotype considered to represent pain. In the face of tissue or nerve injury, the afferent encoding systems display robust changes in the input-output function, leading to an ongoing sensation reported as painful and sensitization of the nociceptors such that an enhanced pain state is reported for a given somatic or visceral stimulus. Our understanding of the mechanisms underlying this non-linear processing of nociceptive stimuli has led to our appreciation of the role played by the functional interactions of neural and immune signaling systems in pain phenotypes. In pathological states, neural systems interact with the immune system through the actions of a variety of soluble mediators, including cytokines. Cytokines are recognized as important mediators of inflammatory and neuropathic pain, supporting system sensitization and the development of a persistent pathologic pain. Cytokines can induce a facilitation of nociceptive processing at all levels of the neuraxis including supraspinal centers where nociceptive input evokes an affective component of the pain state. We review here several key proinflammatory and anti-inflammatory cytokines/chemokines and explore their underlying actions at four levels of neuronal organization: (1) peripheral nociceptor termini; (2) dorsal root ganglia; (3) spinal cord; and (4) supraspinal areas. Thus, current thinking suggests that cytokines by this action throughout the neuraxis play key roles in the induction of pain and the maintenance of the facilitated states of pain behavior generated by tissue injury/inflammation and nerve injury.

Characterization of burning mouth syndrome profiles based on response to a local anaesthetic lozenge

OBJECTIVE

Burning mouth syndrome (BMS) is a chronic oral pain condition with unknown aetiology but assumed to involve peripheral/central neuropathological and immune-mediated inflammatory factors. We aimed at characterizing inflammatory and neurogenic profiles and oral symptomatology of patients with BMS based on response to a local anaesthetic lozenge.

METHODS

Patients with BMS were divided into an Effect (n = 13), No effect (n = 8) or Unspecified (n = 2) group according to their response to a local anaesthetic lozenge on oral pain. Inflammation was assessed in blood plasma and saliva by analyses of IL-6, IL-8, IL-17A, IL-23 and TNF-α levels. The degree of inflammation and distribution of oestrogen receptor, NGF, NGF-receptor, TRPV-1 and IL-17F in buccal mucosal tissue were investigated by immunohistochemistry.

RESULTS

Immunoreactivity to the oestrogen receptor was most intense in the Effect group, whereas the No effect group tended to have higher plasma levels of the pro-inflammatory cytokines.

CONCLUSIONS

Our findings indicate that the response to treatment with local anaesthesia enables subgrouping of patients with BMS according to the potential pathogenic mechanisms. Effect of local anaesthesia indicates a peripheral neuropathology involving lack of oestrogen and upregulation of oestrogen receptors, and no effect indicates a systemic inflammation-induced mechanism leading to increased levels of plasma cytokines.

Effect of antidepressant treatment on plasma levels of neuroinflammation-associated molecules in patients with somatic symptom disorder with predominant pain around the orofacial region

OBJECTIVE

Burning mouth syndrome (BMS) and atypical odontalgia (AO) are examples of somatic symptom disorders with predominant pain around the orofacial region. Neuroinflammation is thought to play a role in the mechanisms, but few studies have been conducted. We aimed to better understand the role of neuroinflammation in the pathophysiology and treatment of BMS/AO.

METHODS

Plasma levels of 28 neuroinflammation-related molecules were determined in 44 controls and 48 BMS/AO patients both pretreatment and 12-week post-treatment with duloxetine.

RESULTS

Baseline plasma levels of interleukin (IL)-1β (p < .0001), IL-1 receptor antagonist (p < .001), IL-6 (p < .0001), macrophage inflammatory protein-1β (p < .0001), and platelet-derived growth factor-bb (.04) were significantly higher in patients than in controls. Plasma levels of granulocyte macrophage colony stimulating factor were significantly higher in patients than in controls (p < .001) and decreased with treatment (.009). Plasma levels of eotaxin, monocyte chemoattractant protein-1, and vascular endothelial growth factor decreased significantly with treatment (p < .001, .022, and .029, respectively).

CONCLUSIONS

Inflammatory mechanisms may be involved in the pathophysiology and/or treatment response of somatic symptom disorders with predominant pain around the orofacial region.

Cytokine levels and their role in the etiopathogenesis of Burning Mouth Syndrome: A systematic review

Introduction

Burning Mouth Syndrome is characterized by variable symptoms that include pain, burning and paraguesia in an otherwise healthy-appearing oral mucosa. Although the etiopathogenesis of Burning Mouth Syndrome is unknown, some studies provide evidence of subclinical inflammation leading to disrupted cytokine levels.

Aim

To investigate the expression of cytokines and role in the etiopathogenesis of Burning Mouth Syndrome.

Methods

Online databases (MEDLINE and EMBASE) were searched from November 1986 to November 2018 for case control/cross-sectional studies comparing the levels of cytokines in patients with Burning Mouth Syndrome and healthy controls.

Results

A total of eight studies were included in the current review. Four studies were of high and four studies were of moderate quality. Seven studies evaluated IL-6, out of which four showed comparable results, two showed higher levels and one study reported lower levels in Burning Mouth Syndrome patients compared to controls. Four studies assessed IL-2, out of which two reported comparable results whereas one study reported higher levels and one study reported lower levels in Burning Mouth Syndrome patients compared to controls. IL-10 levels were measured in three studies that reported no significant differences in the levels between Burning Mouth Syndrome and healthy controls.

Discussion and conclusion

The etiopathogenesis of Burning Mouth Syndrome is multifactorial. Studies have provided scientific evidence that inflammation plays a key role in Burning Mouth Syndrome pathogenesis. However, whether up-regulation or down-regulation of specific cytokines contribute to the etiopathogenesis of Burning Mouth Syndrome remains debatable. Further high-quality studies with larger sample size and assessing a wider array of cytokines are warranted in order to obtain strong conclusions.

Cycle ergometer training enhances plasma interleukin-10 in multiple sclerosis

The objective was to determine plasma levels of pro- (IL-12p70/IL-6) and anti-inflammatory (IL-10) cytokines before and after cycle ergometer training in healthy control (HC) and people with multiple sclerosis (pwMS), and to correlate plasma cytokines with physical/mental health. Study participants cycled for 30 min at 65-75% age-predicted maximal heart rate, twice a week for 8 weeks during supervised sessions. We determined that plasma IL-10 expression was lower in pwMS, compared to HCs, and that exercise augmented IL-10 in pwMS to baseline levels in HCs. Furthermore, plasma isolated from pwMS displayed enhanced expression of the pro-inflammatory cytokines IL-12p70/IL-6. Plasma cytokine signatures correlated with physical/mental health. Overall, this study highlights the potential of a short-term exercise programme to regulate circulating cytokine profiles with relevance to pwMS.