Serum, Saliva, and Urine Irisin with and Without Acute Appendicitis and Abdominal Pain

Salivary and serum irisin in healthy adults before and after exercise

Irisin is an exercise-induced cytokine mainly secreted by myocytes. Circulating level of irisin can increase in response to acute exercise, promoting pleiotropic effects on health. Generally, irisin is evaluated in blood, however, its collection is invasive. Saliva sample would not have any risk associated with blood collection and would represent a less invasive method for irisin detection. Until now, there are only a few studies that have analyzed irisin levels in saliva. In the present research, five healthy male adults performed an incremental exercise until exhaustion on cycle ergometer. Serum and saliva samples were collected before exercise and 15min, 24h and 48h after reaching the exhaustion. Irisin was detected by ELISA assay. Serum and salivary irisin levels increased from baseline to 24h post exercise and reverted to basal levels after 48h of rest. A significant rise of both serum and salivary irisin level at 24h (p≤0.05) compared to baseline levels was found. Furthermore, a significant correlation between irisin percentage change in serum and saliva from baseline to 24h post exercise was detected (r=0.92, p<0.05). Despite the relatively limited sample, this research suggests that collecting saliva samples might represent a valid and less invasive method to detect irisin level changes induced by exercise.

Salivary and serum irisin in healthy adults before and after exercise

Irisin is an exercise-induced cytokine mainly secreted by myocytes. Circulating level of irisin can increase in response to acute exercise, promoting pleiotropic effects on health. Generally, irisin is evaluated in blood, however, its collection is invasive. Saliva sample would not have any risk associated with blood collection and would represent a less invasive method for irisin detection. Until now, there are only a few studies that have analyzed irisin levels in saliva. In the present research, five healthy male adults performed an incremental exercise until exhaustion on cycle ergometer. Serum and saliva samples were collected before exercise and 15min, 24h and 48h after reaching the exhaustion. Irisin was detected by ELISA assay. Serum and salivary irisin levels increased from baseline to 24h post exercise and reverted to basal levels after 48h of rest. A significant rise of both serum and salivary irisin level at 24h (p≤0.05) compared to baseline levels was found. Furthermore, a significant correlation between irisin percentage change in serum and saliva from baseline to 24h post exercise was detected (r=0.92, p<0.05). Despite the relatively limited sample, this research suggests that collecting saliva samples might represent a valid and less invasive method to detect irisin level changes induced by exercise.

Molecular Basis of Irisin Regulating the Effects of Exercise on Insulin Resistance

Insulin resistance is recognized as one major feature of metabolic syndrome, and frequently emerges as a difficult problem encountered during long-term pharmacological treatment of diabetes. Insulin resistance often causes organs or tissues, such as skeletal muscle, adipose, and liver, to become less responsive or resistant to insulin. Exercise can promote the physiological function of those organs and tissues and benefits insulin action via increasing insulin receptor sensitivity, glucose uptake, and mitochondrial function. This is done by decreasing adipose tissue deposition, inflammatory cytokines, and oxidative stress. However, understanding the mechanism that regulates the interaction between exercise and insulin function becomes a challenging task. As a novel myokine, irisin is activated by exercise, released from the muscle, and affects multi-organ functions. Recent evidence indicates that it can promote glucose uptake, improve mitochondrial function, alleviate obesity, and decrease inflammation, as a result leading to the improvement of insulin action. We here will review the current evidence concerning the signaling pathways by which irisin regulates the effect of exercise on the up-regulation of insulin action in humans and animals.

Irisin at the crossroads of inter-organ communications: Challenge and implications

The physiological functions of organs are intercommunicated occurring through secreted molecules. That exercise can improve the physiological function of organs or tissues is believed by secreting myokines from muscle to target remote organs. However, the underlying mechanism how exercise regulates the inter-organ communications remains incompletely understood yet. A recently identified myokine-irisin, primarily found in muscle and adipose and subsequently extending to bone, heart, liver and brain, provides a new molecular evidence for the inter-organ communications. It is secreted under the regulation of exercise and mediates the intercommunications between exercise and organs. To best our understanding of the regulatory mechanism, this review discusses the recent evidence involving the potential molecular pathways of the inter-organ communications, and the interactions between signalings and irisin in regulating the impact of exercise on organ functions are also discussed.

Novel molecular biomarkers and diagnosis of acute appendicitis in children

Reliable and efficient diagnosis of pediatric appendicitis is essential for the establishment of a clinical management plan and improvement of patient outcomes. Current strategies used to diagnose a child presenting with a suspected appendicitis include laboratory studies, clinical scores and diagnostic imaging. Although these modalities work in conjunction with each other, one optimal diagnostic strategy has yet to be agreed upon. The recent introduction of precision medicine techniques such as genomics, transcriptomics, proteomics and metabolomics has increased both the diagnostic sensitivity and specificity of appendicitis. Using these novel strategies, the integration of precision medicine into clinical practice via point-of-care technologies is a plausible future. These technologies would assist in the screening, diagnosis and prognosis of pediatric appendicitis.

The diagnostic value of ischaemia-modified albumin in acute abdominal pain

AIM

The differential diagnosis of paediatric patients admitted to the emergency department presenting with acute abdominal pain may be difficult. This study aims to investigate the diagnostic value of ischaemia-modified albumin (IMA) in the differential diagnosis of acute abdominal pain in children and in distinguishing surgical from non-surgical cases.

METHODS

The study was conducted with a total of 152 subjects who provided informed consent, including 112 patients admitted to the paediatric emergency department and paediatric surgical clinic and 40 healthy control subjects. Blood samples were collected after initial examination to determine IMA, white blood cell (WBC) and C-reactive protein (CRP) values.

RESULTS

Mean IMA values of patients with acute appendicitis (AA), perforated appendicitis (PA) and non-specific abdominal pain were significantly higher compared to the control group. Mean IMA values of the AA and PA cases were also significantly higher compared to the group with non-specific abdominal pain. No significant difference was determined in mean IMA between the AA and PA groups. WBC and CRP levels of the AA and PA groups were significantly higher compared to the group with non-specific abdominal pain.

CONCLUSION

Our study shows that IMA, together with WBC and CRP, may be a biomarker capable of assisting the differential diagnosis of acute abdominal pain in children and distinguishing surgical from non-surgical cases.

Comparison of irisin hormone expression between thyroid cancer tissues and oncocytic variant cells

Objective: The incidence of thyroid cancer has been continuously increasing. The main objective of this study was to investigate irisin expression in various thyroid pathologies and to compare these expression patterns with irisin expression in healthy thyroid tissues.

Methods: The study groups consisted of 20 cases each of control thyroid tissue, Hashimoto’s thyroiditis, thyroid papillary carcinoma, oncocytic papillary carcinoma, follicular thyroid carcinoma, oncocytic follicular thyroid carcinoma, medullary thyroid carcinoma, anaplastic thyroid carcinoma. Irisin expression was evaluated using immunohistochemistry. Irisin levels in thyroid tissue supernatants were measured using ELISA.

Results: Patients with HT showed increased irisin expression compared with controls (p<0.05). In addition, mild immunoreactivity was observed in the thyroid tissues of patients with papillary carcinoma while significantly increased irisin immunoreactivity was observed tissues of patients with oncocytic papillary carcinoma (p<0.05). There was no difference in irisin immunoreactivity in thyroid tissues between patients with follicular carcinoma and controls. However, irisin immunoreactivity was higher in tissues of patients with oncocytic follicular carcinoma than in tissues of patients with follicular carcinoma (p<0.05). No irisin immunoreactivity was observed in tissues of patients with medullary carcinoma, a malignant tumor the thyroid; however, irisin expression was significantly increased in tissues of patients with anaplastic carcinoma compared with that in tissues of controls (p<0.05). Furthermore, in all thyroid tissues with irisin expression, irisin immunoreactivity was observed in follicular cells, indicating that irisin is produced by these cells.

Conclusion: Irisin is a novel potential immunohistochemical marker for differentiating oncocytic variants of papillary and FTCs from papillary and follicular thyroid cancers.

Saliva and Blood Asprosin Hormone Concentration Associated with Obesity

BACKGROUND

The aim was to investigate the amounts of saliva and serum asprosin in order to determine whether it is related to obesity and whether salivary glands synthesize asprosin or not.

METHODS

A total of 116 underweight, normal weight, overweight, and obese (class I, class II, and class III) volunteers participated in the study. Saliva and blood samples were collected simultaneously from the participants. The amounts of asprosin in saliva, salivary gland tissue supernatants, and bloods were determined by ELISA, whereas asprosin synthesis sites of salivary gland tissues were determined immunohistochemically.

RESULTS

The amount of asprosin from the lowest to the highest was in the order as follows: underweight, normal weight (control), overweight, and obese classes I and III. The lowest level of asprosin was detected in underweight individuals. It was also found that the interlobular striated ducts and the interlobular ducts of the submandibular and parotid salivary glands produce asprosin. According to these data, the asprosin level is related with obesity as the amount increases in accordance with increasing body mass index (BMI). On the other hand, there is also a relationship between the underweight and asprosin because the amount decreases with BMI decrease.

CONCLUSIONS

Asprosin, a new adipokine, may be a novel indicator of adipose tissue mass. Therefore, we anticipate that antiasprosin preparations may be an alternative in the treatment of obesity in the future.

Relationship of Circulating Irisin with Body Composition, Physical Activity, and Cardiovascular and Metabolic Disorders in the Pediatric Population

Exercise-induced irisin, a recently discovered myokine, has been linked to insulin resistance, obesity, and other diseases in adults; however, information in children is scarce and contradictory. We analyzed the limited evidence of irisin’s effects in children and adolescents, and its association with body composition, exercise training, cardiovascular risk factors, and metabolic diseases, as well as the results of dietetic interventions. Both positive and negative correlations between irisin concentrations and body mass index, fat mass, fat-free mass, and other anthropometric parameters were found. Likewise, contradictory evidence was shown associating irisin plasma levels with cardiovascular and metabolic parameters such as glucose, insulin resistance, and cholesterol and other lipid and fatty acid plasma levels in healthy children, as well as in those with obesity and the metabolic syndrome. Gender, puberty, and hormonal differences were also examined. Furthermore, important contradictory findings according to the type and duration of exercise and of dietetic interventions in healthy and unhealthy subjects were demonstrated. In addition, correlations between mother–infant relations and circulating irisin were also identified. This review discusses the potential role of irisin in health and disease in the pediatric population.

The Diagnostic Value of Irisin in Pediatric Patients with Acute Abdominal Pain

Objectives

Diagnosis of pediatric patients presenting to the Emergency Department with acute abdominal pain is not always easy. The purpose of this study was to investigate the effectiveness of irisin, a peptide hormone with reactivity shown in the appendix and neutrophils, in the differential diagnosis of pediatric patients with acute abdominal pain.

Methods

162 subjects consenting to participate, including 112 patients presenting to the Pediatric Emergency and Pediatric Surgery clinics with acute abdominal pain and 50 controls, were enrolled in the study. Blood was collected from all patients following initial examination for irisin, WBC, and CRP investigation.

Results

Mean irisin levels in cases of acute appendicitis (AA) and perforated appendicitis (PA) were statistically significantly higher compared to nonspecific abdominal pains and the control group. No statistically significant difference was observed in irisin levels between AA and PA cases. WBC and CRP levels were also significantly higher in cases of AA and PA compared to nonspecific abdominal pains.

Conclusions

Differential diagnosis of acute abdominal pains in children and deciding on surgery are a difficult and complex process. Our study shows that irisin can be a useful biomarker in differentiating AA and PA from other acute abdominal pains in children.

An update on the role of irisin in the regulation of endocrine and metabolic functions

Irisin is a novel myokine and adipokine that has gained much attention recently due to its mechanisms of action. Irisin is secreted following proteolytic cleavage of its precursor fibronectin type III domain containing 5 (FNDC5). Following its release, irisin exerts its major action by increasing the expression of mitochondrial uncoupling protein 1 (UCP 1), which facilitates the conversion of white adipose tissue (WAT) into beige adipose tissue. Irisin is distributed in various body tissues and several actions have been attributed to its presence in those tissues. It has been suggested that it plays a role in metabolic diseases, ageing, inflammation and neurogenesis. However, the circulating levels of irisin are modulated by several factors such as diet, obesity, exercise, pharmacological agents and different pathological conditions. In this review, we have discussed the mechanisms by which irisin influences the functions of different body systems and how external factors in turn affect the circulating level of irisin. In conclusion, modification of circulating irisin level may help in the management of a variety of endocrine and metabolic disorders.

Measuring myokines with cardiovascular functions: pre-analytical variables affecting the analytical output

In the last few years, a growing number of molecules have been associated to an endocrine function of the skeletal muscle. Circulating myokine levels, in turn, have been associated with several pathophysiological conditions including the cardiovascular ones. However, data from different studies are often not completely comparable or even discordant. This would be due, at least in part, to the whole set of situations related to the preparation of the patient prior to blood sampling, blood sampling procedure, processing and/or store. This entire process constitutes the pre-analytical phase. The importance of the pre-analytical phase is often not considered. However, in routine diagnostics, the 70% of the errors are in this phase. Moreover, errors during the pre-analytical phase are carried over in the analytical phase and affects the final output. In research, for example, when samples are collected over a long time and by different laboratories, a standardized procedure for sample collecting and the correct procedure for sample storage are acknowledged. In this review, we discuss the pre-analytical variables potentially affecting the measurement of myokines with cardiovascular functions.

Serum irisin levels correlated to peritoneal dialysis adequacy in nondiabetic peritoneal dialysis patients

Background

Irisin is a recently discovered myokine thought to be involved in multiple metabolism abnormalities in most dialysis patients. However, the myokine has not been thoroughly studied in peritoneal dialysis. This study aimed to evaluate serum irisin levels and establish their relation to dialysis adequacy, insulin resistance, and bone metabolism status in patients on peritoneal dialysis.

Methods

A total of 59 nondiabetic prevalent peritoneal dialysis patients and 52 age- and sex-matched healthy controls were enrolled in this cross-sectional study. Serum irisin concentration was assessed by enzyme-linked immunosorbent assay. The correlations between serum irisin and dialysis adequacy, clinical, and metabolic variables were investigated.

Results

Serum irisin levels were lower in nondiabetic peritoneal dialysis patients (17.02ng/ml) compared with healthy controls (22.17ng/ml, P<0.001). Multivariate regression analysis revealed that fasting glucose levels were correlated inversely with serum irisin levels in peritoneal dialysis patients. Serum irisin levels were associated with neither insulin resistance nor bone metabolism in our patients. Serum irisin levels were positively associated with peritoneal Kt/V_urea (β = 4.933, 95% confidence interval [CI] = 0.536–9.331, P = 0.029) and peritoneal C_Cr (β = 0.259, 95% CI = 0.053–0.465, P = 0.015) among peritoneal dialysis patients.

Conclusions

The study demonstrated that non-diabetic peritoneal dialysis patients have lower serum irisin levels, and the levels were correlated with peritoneal dialysis adequacy, indicating adequate dialysis may improve irisin secretion. Additional studies are needed to provide a confirmation.

Relationship between Irisin Concentration and Serum Cytokines in Mother and Newborn

Introduction

Irisin is considered to be a myokine and adipokine that may also participate in reproductive functions, as it increases significantly throughout pregnancy. However, the regulation of circulating irisin and its relationship with other cytokines has not been assessed thus far in pregnant women and their offspring.

Objective

The aim of this study was to evaluate differences in irisin and cytokine concentrations between women at the end of pregnancy and their offspring, as well as the relationship between maternal and newborn irisin and maternal and newborn biomarkers.

Methods

Twenty-eight mother/newborn pairs were included in this study. The following biomarkers were evaluated in maternal venous and arterial umbilical cord blood samples: irisin, 27 cytokine panel, total antioxidant capacity (TAC), total plasma protein, and free fatty acid concentration.

Results

The newborns had significantly lower irisin concentrations compared to their mothers (p = 0.03), but this difference was present only in babies born from mothers without labor prior to cesarean section delivery (p = 0.01). No significant differences in maternal and newborn irisin concentrations were found between diabetic and non-diabetic mothers or between overweight/obese and normal weight mothers. A significant positive correlation was found between TAC level and irisin concentration in newborns. Maternal and newborn interleukin (IL)-1β, IL-1RA, IL-5, IL-7, and interferon gamma-induced protein (IP)-10 levels were significantly positively correlated with irisin concentrations in both study groups. In addition, maternal IL1β, IL-5, IL-7, and IP-10 levels positively predicted maternal irisin concentrations. Furthermore, arterial cord blood TAC and IL-1β and IL1-RA levels positively predicted newborn irisin concentrations. Multiple regression analyses showed that maternal IL-13 negatively predicted offspring irisin levels (p = 0.03) and that maternal IL-1β positively predicted newborn irisin concentrations (p = 0.046).

Conclusion

No evidence was found that serum irisin concentrations in mothers at pregnancy termination or those of their newborns correlated with maternal body mass index, the presence of diabetes mellitus, or free fatty acid levels. However, the results of this study indicated that cytokines might predict irisin concentration in mothers and their offspring, although interactions between irisin levels during pregnancy and the newborn have not yet been fully elucidated.