Biomarkers alterations in trapezius muscle after an acute tissue trauma: A human microdialysis study

Aims

Alteration in muscle milieu has been proposed as one of the main contributors underlying chronic musculoskeletal pain (CMP). Microdialysis (MD) provides real-time information on release of pain and metabolic biomarkers in muscle. However, insertion of MD probe causes a local tissue trauma, which may affect the tissue milieu. Whether an acute tissue trauma alter pain and metabolite biomarkers in trapezius muscle of patients with CMP is not known. Hence, this study investigated changes in muscle metabolites following MD probe insertion in patients with CMP in comparison with healthy controls.

Methods

Nineteen patients (11 women and 8 men; 41.4 years) with CMP and 20 pain-free volunteers (10 women and 10 men; 36.5 years) were recruited (project approval number: 2013/151- 31). Baseline pressure pain thresholds (PPT) at trapezius muscle were obtained bilaterally with a reference point at the tibialis muscle. Pain questionnaires were used for determining levels of anxiety and depression and catastrophizing impact. Interstitial samples were collected from trapezius muscles by aid of MD (20 kDa cut-off) during a period of 40 min. Collected dialysates at 2 time-points of 20 and 40 min were stored at −70 °C until analysis. Concentrations of glucose, lactate, pyruvate, glycerol, and glutamate were analyzed by ISCUSSflex. P ≤ 0.05 was considered significant.

Results

No potential case with respect to anxiety, depression or catastrophizing impact was found. Lower PPTs were found in CMP group (P ≤ 0.05). Significantly lower levels of pyruvate were found in CMP group at both 20 min (P = 0.003) and 40 min (P = 0.006). Gender-based analysis indicated higher concentrations of glutamate in female patients with CMP.

Conclusions

This study was first to demonstrate metabolite alterations during trauma phase of MD in trapezius muscles of CPM compared with healthy controls. This model proved beneficial for investigating pain and metabolic biomarkers during acute phase of MD.

Different DHEA-S Levels and Response Patterns in Individuals with Chronic Neck Pain, Compared with a Pain Free Group-a Pilot Study

Objective

To test, in this pilot study, whether DHEA-S (Dehydroepiandrosterone, sulfated form) plasma levels are lower among persons with chronic neck pain, compared to control persons, and to investigate the DHEA-S response after a physical exercise.

Subjects

Included were 12 persons with chronic neck pain and eight controls without present pain, all 18 and 65 years of age. Exclusion criteria for both groups were articular diseases or tendinosis, fibromyalgia, systemic inflammatory and neuromuscular diseases, pain conditions due to trauma, or severe psychiatric diseases.

Design and methods

The participants arm-cycled on an ergometer for 30 minutes. Blood samples were taken before, 60 minutes, and 150 minutes after this standardized physical exercise.

Results

The estimated plasma DHEA-S levels at baseline were 2.0 µmol/L (95% confidence interval [CI] 1.00; 4.01) in the pain group and 4.1 µmol/L (95% CI2.0; 8.6) in the control group, adjusted for sex, age, body mass index (BMI), and Shirom-Melamed Burnout Questionnaire (SMBQ), with a ratio of 0.48 ( P  = 0.094).

Conclusions

In this pilot study, the plasma DHEA-S levels appeared to be lower among the persons with chronic neck pain, compared with the control group. It was indicated that DHEA-S decreased during the physical exercise in the control group, and either increased or was unaffected in the chronic pain group.

Protein profiles of nasal lavage fluid from individuals with work-related upper airway symptoms associated with moldy and damp buildings

Upper airway irritation is common among individuals working in moldy and damp buildings. The aim of this study was to investigate effects on the protein composition of the nasal lining fluid. The prevalence of symptoms in relation to work environment was examined in 37 individuals working in two damp buildings. Microbial growth was confirmed in one of the buildings. Nasal lavage fluid was collected from 29 of the exposed subjects and 13 controls, not working in a damp building. Protein profiles were investigated with a proteomic approach and evaluated by multivariate statistical models. Subjects from both workplaces reported upper airway and ocular symptoms. Based on protein profiles, symptomatic subjects in the two workplaces were discriminated from each other and separated from healthy controls. The groups differed in proteins involved in inflammation and host defense. Measurements of innate immunity proteins showed a significant increase in protein S100-A8 and decrease in SPLUNC1 in subjects from one workplace, while alpha-1-antitrypsin was elevated in subjects from the other workplace, compared with healthy controls. The results show that protein profiles in nasal lavage fluid can be used to monitor airway mucosal effects in personnel working in damp buildings and indicate that the profile may be separated when the dampness is associated with the presence of molds.

Increased pain and muscle glutamate concentration after single ingestion of monosodium glutamate by myofascial temporomandibular disorders patients

BACKGROUND

A randomized, double-blinded, placebo-controlled study was conducted to investigate if single monosodium glutamate (MSG) administration would elevate muscle/serum glutamate concentrations and affect muscle pain sensitivity in myofascial temporomandibular disorders (TMD) patients more than in healthy individuals.

METHODS

Twelve myofascial TMD patients and 12 sex- and age-matched healthy controls participated in two sessions. Participants drank MSG (150 mg/kg) or NaCl (24 mg/kg; control) diluted in 400 mL of soda. The concentration of glutamate in the masseter muscle, blood plasma and saliva was determined before and after the ingestion of MSG or control. At baseline and every 15 min after the ingestion, pain intensity was scored on a 0-10 numeric rating scale. Pressure pain threshold, pressure pain tolerance (PPTol) and autonomic parameters were measured. All participants were asked to report adverse effects after the ingestion.

RESULTS

In TMD, interstitial glutamate concentration was significantly greater after the MSG ingestion when compared with healthy controls. TMD reported a mean pain intensity of 2.8/10 at baseline, which significantly increased by 40% 30 min post MSG ingestion. At baseline, TMD showed lower PPTols in the masseter and trapezius, and higher diastolic blood pressure and heart rate than healthy controls. The MSG ingestion resulted in reports of headache by half of the TMD and healthy controls, respectively.

CONCLUSION

These findings suggest that myofascial TMD patients may be particularly sensitive to the effects of ingested MSG. WHAT DOES THIS STUDY ADD?': Elevation of interstitial glutamate concentration in the masseter muscle caused by monosodium glutamate (MSG) ingestion was significantly greater in myofascial myofascial temporomandibular disorders (TMD) patients than healthy individuals. This elevation of interstitial glutamate concentration in the masseter muscle significantly increased the intensity of spontaneous pain in myofascial TMD patients.

Protein alterations in women with chronic widespread pain—A proteomic study of the trapezius muscle

Aim

This study aims to investigate the proteome of trapezius muscle biopsies of women with chronic widespread pain (CWP) compared to female pain-free controls using proteomic tools. CWP has a high prevalence (10%) resulting in prominent negative individual and societal consequences. There is no clear consensus concerning the etiology behind CWP although alterations in the central processing of nociception maintained by peripheral nociceptive input has been suggested.

Methods

Two-dimensional gel electrophoresis (2-DE) analysis and nano-liquid chromatography/mass spectrometry (nLC/MS) was used to study the proteome differences of biopsies from the trapezius muscle between 18 female patients diagnosed with CWP and 19 healthy female controls.

Results

The proteomic analysis revealed 17 proteins to be statistically significantly expressed between the two groups by which 12 were up-regulated and 5 were down-regulated in the CWP group compared to healthy controls. Many of the proteins were important enzymes in metabolic pathways like the glycolysis and gluconeogenesis (Triosephosphate isomerase, Glyceraldehyde-3-phosphate dehydrogenase, Pyruvate kinase isoenzyme M1/M2 and Fructose-bisphosphate aldolase A, all up-regulated in CWP). Other proteins are associated with muscle damage (Ankyrin repeat domain-containing protein 2, down-regulated in CWP), muscle recovery (Alpha-crystallin B chain, up-regulated in CWP) stress and inflammation (carbonic anhydrase 3, up-regulated in CWP). The contractile and structural proteins found have been associated with various types of myopathies (Actin alpha skeletal muscle, up-regulated, Troponin T slow skeletal muscle and Desmin, down-regulated in CWP).

Conclusions

In conclusion, the expression of these proteins belonging to the protein groups, contractile, stress and inflammatory, structural, and metabolic, suggests abnormalities and alterations in the myalgic trapezius muscle.

Comparative metabolomics of muscle interstitium fluid in human trapezius myalgia: an in vivo microdialysis study

Purpose

The mechanisms behind trapezius myalgia are unclear. Many hypotheses have been presented suggesting an altered metabolism in the muscle. Here, muscle microdialysate from healthy and myalgic muscle is analysed using metabolomics. Metabolomics analyse a vast number of metabolites, enabling a comprehensive explorative screening of the cellular processes in the muscle.

Methods

Microdialysate samples were obtained from the shoulder muscle of healthy and myalgic subjects that performed a work and stress test. Samples from the baseline period and from the recovery period were analysed using gas chromatography—mass spectrometry (GC–MS) together with multivariate analysis to detect differences in extracellular content of metabolites between groups. Systematic differences in metabolites between groups were identified using multivariate analysis and orthogonal partial least square discriminate analysis (OPLS-DA). A complementary Mann–Whitney U test of group difference in individual metabolites was also performed.

Results

A large number of metabolites were detected and identified in this screening study. At baseline, no systematic differences between groups were observed according to the OPLS-DA. However, two metabolites, l-leucine and pyroglutamic acid, were significantly more abundant in the myalgic muscle compared to the healthy muscle. In the recovery period, systematic difference in metabolites between the groups was observed according to the OPLS-DA. The groups differed in amino acids, fatty acids and carbohydrates. Myristic acid and putrescine were significantly more abundant and beta-d-glucopyranose was significantly less abundant in the myalgic muscle.

Conclusion

This study provides important information regarding the metabolite content, thereby presenting new clues regarding the pathophysiology of the myalgic muscle.

The effects of physical exercise and smoking habits on the expression of SPLUNC1 in nasal lavage fluids from allergic rhinitis subjects

OBJECTIVE

Palate lung nasal epithelial clone (PLUNC) is a family of proteins, which are proposed to participate in the innate immune defense against infections in the upper aero-digestive tract. The aim of this study was to investigate the expression of SPLUNC1 in allergic rhinitis subjects with considerations taken to the mucosal function and smoking habits.

METHODS

The participants, recruited from a cohort followed from infancy, were re-examined at the age of 18 years regarding allergy development. Based on medical histories and skin prick tests the participants were classified into groups with persistent allergic rhinitis (n=18), intermittent allergic rhinitis (n = 8) and healthy controls (n = 13). Seven subjects (3, 2 and 2 in each group, respectively) reported smoking habits. The SPLUNC1 levels in nasal lavage fluids were analyzed by Western blot. Changes in the volume of the proper nasal cavity before and after physical exercise (Vol2(increase)) were analyzed by acoustic rhinometry.

RESULTS

Compared to the control group the SPLUNC1 level was significantly lower in the persistent allergy group (3.8 ± 3.4 OD vs. 1.3 ± 1.5 OD; p = 0.02), but not in the intermittent allergy group without current exposure to allergens (3.6 ± 4.7 OD). No differences were found in Vol2(increase) between any of the allergy groups and controls. In smokers Vol2(increase) was significantly reduced (p < 0.01) and the SPLUNC1 levels were lower compared to non-smokers. A significant correlation was found between SPLUNC1 and Vol2(increase) (p < 0.01; r = 0.53) in non-smokers.

CONCLUSIONS

Current allergen exposure has an impact on SPLUNC1 expression in nasal lavage fluid, why allergy ought to be considered in study populations where analyses of SPLUNC1 levels are included in the reports. The normal nasal decongestion after exercise was not affected by allergy in contrast to smoking habits. The correlation between SPLUNC1 levels and Vol2(increase) in non-smokers may indicate involvement of SPLUNC1in the regulation of the normal function of the nasal mucosa. Complementary studies are needed to confirm the smoke-related reduction of SPLUNC1 expression and to analyze the possible participation of SPLUNC1 in the nasal mucosa regulation.

Experimental myalgia induced by repeated infusion of acidic saline into the human masseter muscle does not cause the release of algesic substances

BACKGROUND

Animal studies have shown that two repeated intramuscular injections of acidic saline induce mechanical allodynia that lasts for 4 weeks with spread to the contralateral side. In this study, we tested the hypothesis that two repeated intramuscular infusions of acidic saline into the human masseter muscle is associated with pain, mechanical allodynia and release of algesic substances. Eighteen healthy volunteers participated. On day 1, 2.5 mL of acidic saline (pH 3.3) was infused into one of the masseter muscles and isotonic saline (pH 6.0) into the other (randomized and single-blind). Two days later, intramuscular microdialysis was performed to sample serotonin, glutamate, pyruvate, lactate and glucose, during which the saline infusions were repeated. Pain and pressure pain thresholds (PPTs) were recorded before and after infusions on both days.

RESULTS

Pain intensity induced by the infusions was higher after acidic than that after isotonic saline (p < 0.05). PPTs were decreased on both sides after microdialysis compared with baseline day 1 (p's < 0.05), but there were no differences in PPTs between sides at any time point. The levels of serotonin, glutamate, pyruvate, lactate or glucose did not change significantly during microdialysis.

CONCLUSION

Infusion of acidic saline caused low levels of muscle pain, but no mechanical allodynia and no increased release of algesic substances. The value of this model appears modest, but future studies could be performed with larger sample size and higher flow rate before definite conclusions about the validity of the model for craniofacial myalgia can be drawn.

Responses of algesic and metabolic substances to 8 h of repetitive manual work in myalgic human trapezius muscle

The trapezius muscle often develops pain as the result of repetitive and stressful work tasks although it is unclear to what extent this pain is due to alterations in muscle concentrations of algesic/nociceptive substances. Twenty women with chronic neck- and shoulder pain (TM) whose work required highly repetitive work tasks and 20 pain-free female colleagues (CON) were studied during and after a full 8-hour workday. We collected microdialysates from their dominant/most painful trapezius muscle; concentrations of serotonin, glutamate, lactate, pyruvate, potassium, bradykinin, and cytokines and blood flow were determined. In addition, we measured surface electromyogram, task exposure level, pain intensity, perceived mental stress, and urine-cortisol. In connection to the clinical neck and shoulder examination, we determined pressure pain thresholds (PPTs) over the trapezius and tibialis muscles. TM had higher concentrations of glutamate (71+/-42 vs. 36+/-15 micromol l(-1)) and pyruvate (187+/-89 vs. 125+/-63 micromol l(-1)) than CON. Interstitial serotonin was higher in TM (before work: 10.6+/-10.8 vs. 2.2+/-1.2 nM; after work: 9.2+/-8.3 vs. 1.5+/-2.9 nM). The trapezius blood flow during the working day was higher in TM than in CON. TM had lower PPT and higher pain intensity throughout the working day. No differences in EMG, task exposure level, mental stress, or urine-cortisol in the groups were found. These findings support the idea that peripheral nociceptive processes are activated in occupationally active subjects, who are diagnosed with trapezius myalgia. In contrast, no sign of low blood flow or increased stress or muscle activity markers were found in TM.

Comparative proteomics of nasal fluid in seasonal allergic rhinitis

A comparative proteomic approach was applied to examine nasal lavage fluid (NLF) from patients with seasonal allergic rhinitis (SAR, n = 6) and healthy subjects (controls, n = 5). NLF samples were taken both before allergy (pollen) season and during season, and proteins were analyzed by two-dimensional gel electrophoresis (2-DE) and matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) after tryptic cleavage. Twenty proteins were selected and quantified. During allergy season, the levels of six sialylated isoforms of PLUNC (palate lung nasal epithelial clone) were lower in SAR patients than controls, as were the levels of six isoforms of von Ebner's gland protein (VEGP), including a previously undescribed form with N-linked glycosylation, and of cystatin S. PLUNC is a new innate immunity protein and VEGP and cystatin S are two endogenous proteinase inhibitors. By contrast, the levels of an acidic form of alpha-1-antitrypsin were higher in SAR patients than controls. One previously unidentified NLF protein was found in all samples from the SAR patients during allergy season but not in any sample before allergy season: this protein was identified as eosinophil lysophospholipase (Charcot-Leyden crystal protein/galactin 10). MS/MS analysis of the N-terminus of the protein showed removal of Met and acetylation of Ser. Altogether, these findings illustrate the potential use of proteomics for identifying protein changes associated with allergic rhinitis and for revealing post-translational modifications of such new potential markers of allergic inflammation.

PLUNC (palate, lung and nasal epithelial clone) proteins in human nasal lavage fluid

PLUNC (palate, lung and nasal epithelial clone) is a newly discovered gene that is expressed in the upper respiratory tract and is suggested to be of importance in host defence against bacteria. We have identified two forms of the PLUNC protein in human nasal lavage fluid (NLF) using two-dimensional gel electrophoresis (2-DE) and MS. The apparent molecular masses and isoelectric points of these forms are 24.8 kDa/pI 5.4 and 25.1 kDa/pI 5.5. Notably, the 24.8 kDa/pI 5.4 form of PLUNC is an abundant protein in the 2-DE protein patterns of NLF from healthy subjects. Decreased levels of PLUNC were found in NLF from smokers and workers exposed to reactive epoxy chemicals, indicating that long-term exposure to airway irritants impairs the production of PLUNC in the upper respiratory tract. We have also investigated the presence of lipopolysaccharide (LPS)-binding proteins in NLF. Five proteins were found to adsorb to a LPS-coated surface; two of these proteins correspond to the two PLUNC forms, as judged by 2-DE pattern matching. For comparison, human saliva was found to contain a set of LPS-binding proteins with similar 2-DE spot positions (the same pIs but somewhat lower apparent molecular masses of approximately 20 kDa). These results indicate that PLUNC may be a new marker of airway inflammation and may play a part in the innate immune response, and that human saliva contains yet other members of the family of LPS-binding proteins.