Impact of spexin on metabolic diseases and inflammation: An updated minireview

Spexin expression in the human bile duct and perihilar cholangiocarcinoma

The bile duct transports bile fluid from the liver to the gallbladder and small intestine. It contains bioactive peptides, including galanin (GAL) and its receptors (GAL1-3-R). Spexin (SPX), a member of the GAL peptide family, activates GAL2-R and GAL3-R. Its expression in perihilar bile ducts or in perihilar cholangiocarcinoma (pCCA), the most common biliary cancer, is largely unknown. This study investigated SPX expression in healthy, cholestatic, and malignant bile duct tissues. Immunohistochemistry was used to evaluate SPX in healthy (n = 4), peritumoral (PIT) (n = 23) and pCCA (n = 34) tissues. Score values of SPX expression were calculated and statistically analyzed. In healthy and PIT tissues with or without cholestasis, SPX expression was predominantly observed in cholangiocytes and nerve fibers. In pCCA, tumor cells also expressed SPX. SPX levels were similar across healthy, peritumoral, and cholangiocytes/tumor cells. In a small pCCA patient cohort (n = 19), SPX expression did not correlate with tumor grade or patient survival (p = 0.0838). The substantial expression of SPX in cholangiocytes and nerve fibers in the bile duct indicates that SPX contributes via galaninergic signaling to gall bladder function. The presence of SPX in submucosal nerve fibers suggests a neuromodulatory role, possibly involving bile duct motility. SPX expression did not correlate with survival in pCCA, whereas previous findings on GAL suggest a prognostic value. This highlights the need for joint studies of SPX and GAL in larger cohorts.

Aerobic training and vitamin D supplementation effects on diabetes-related parameters in a rat model of type 2 diabetes

BACKGROUND

Diabetes mellitus (DM) is characterized by disturbances in glucose, lipid, and energy metabolism, including dyslipidemia and dysregulation of metabolic peptides like spexin; however, the effects of combined interventions, such as aerobic training and nutritional intervention, on these parameters are not fully elucidated. The objective of this study was to investigate the influences of aerobic training (AT) and vitamin D (Vit D) supplementation on the lipid profile and spexin levels in a model of rats with type 2 diabetes (T2D).

METHODS

A total of 56 male Wistar rats were divided into two groups: SHAM (non-diabetic control; n = 8) and diabetic (n = 48). The diabetic rats were further divided into six groups: AT with high doses of vitamin D (D + AT + HD; 10,000 IU/kg/week), AT with moderate doses of vitamin D (D + AT + MD; 5,000 IU/kg/week), high doses of vitamin D (D + HD; 10,000 IU/kg/week), moderate doses of vitamin D (D + MD; 5,000 IU/kg/week), AT receiving vehicle (sesame oil; D + AT + oil), and control (oil-receiving; D + C). To induce type 2 diabetes, rats were first fed a high-fat diet (HFD) for 2 weeks to induce obesity, followed by an intraperitoneal injection of 110 mg/kg nicotinamide and 55 mg/kg streptozotocin (STZ) dissolved in 0.1 M citrate buffer (pH 4.5). Blood samples were collected 48 h after the last training session under anesthesia for measuring spexin levels, and lipid profile parameters. Statistical analyses were performed using the paired t-test, one-way analysis of variance (ANOVA), and Tukey post hoc test.

RESULTS

Compared to the SHAM rats, there were significant increases in body weight, BMI, FI, and WC in the diabetic rats (p < 0.001). Also, there was a significant decrease in body weight, BMI, FI, and WC of the diabetic groups who received interventions, especially in D + AT + HD (body weight: -11.07%, BMI: -10.25%, FI: -19.16%, WC: -16.54%). The lipid profiles were significantly improved, with the lowest total cholesterol (TC), triglycerides (TG), and low-density lipoprotein (LDL) levels and the highest high-density lipoprotein (HDL) levels being found in the D + AT + HD group compared with the D + C group (p < 0.05). Moreover, the D + AT + HD group had elevated spexin levels compared with the other diabetic groups, which may play a metabolic role.

CONCLUSION

AT and Vit D supplementation effectively normalized serum lipids and increased spexin levels in T2D rats. These findings suggest that AT and Vit D supplementation may serve as potential therapeutic strategies for managing T2D and its associated complications. Further studies are needed to elucidate the underlying mechanisms and to evaluate the long-term effects of these interventions in humans.

The relationship between spexin and liver steatosis in polycystic ovary syndrome: a novel analysis using ultrasound-guided attenuation parameter

OBJECTIVE

This study aims to evaluate the relationship between spexin levels and nonalcoholic fatty liver disease in patients with polycystic ovary syndrome.

METHODS

The study included 90 participants, comprising 44 patients diagnosed with polycystic ovary syndrome and 46 age- and body mass index-matched controls. Participants' spexin, glucose, urea, alanine aminotransferase, aspartate aminotransferase, total cholesterol, low-density lipoprotein, high-density lipoprotein, triglycerides, progesterone, follicle-stimulating hormone, luteinizing hormone, estradiol, total testosterone, free testosterone, and dehydroepiandrosterone sulfate levels were measured. The liver steatosis grading was done using the ultrasound-guided attenuation parameter from General Electric Healthcare. The parameters were evaluated between the groups.

RESULTS

Spexin levels in polycystic ovary syndrome patients were significantly lower compared to the control group (p<0.001). Glucose, triglycerides, luteinizing hormone, total testosterone, free testosterone, and dehydroepiandrosterone sulfate levels were found to be significantly higher in polycystic ovary syndrome patients compared to the control group (p<0.001). High-density lipoprotein levels in polycystic ovary syndrome patients were significantly lower compared to the control group (p<0.001). The prevalence of liver steatosis was notably higher among the polycystic ovary syndrome patients compared to the control group (p<0.001). In patients with polycystic ovary syndrome, spexin levels demonstrated significant negative correlations with body mass index, glucose, triglycerides, luteinizing hormone, total testosterone, free testosterone, and dehydroepiandrosterone sulfate (all p<0.001). A strong negative correlation was observed between spexin levels and liver steatosis grading (p<0.001).

CONCLUSION

Spexin is a coordinator in the metabolic relationship between polycystic ovary syndrome and liver health, suggesting its utility as a biomarker for detecting liver steatosis and related metabolic disturbances in this population.

The Investigation of Kisspeptin, Spexin and Galanin in Euthyroid Women with Hashimoto's Thyroiditis

OBJECTIVE

The hallmarks of Hashimoto's thyroiditis (HT) include the destruction of thyroid cells by leading to insulin resistance (IR), hypothyroidism, and metabolic abnormalities. Kisspeptin, spexin, and galanin control appetite and body weight (BW) to regulate metabolisms. Here, we sought to determine if galanin, kisspeptin, and spexin are linked to the pathophysiology of HT in euthyroid female individuals.

METHODS

Forty-five women with HT and 45 healthy control women of the same age participated in the current study. The enzyme-linked immunosorbent assay (ELISA) method was used to measure the serum levels of galanin, spexin, and kisspeptin.

RESULTS

In comparison to the controls, HT patients had significantly higher levels of kisspeptin (p < 0.01), galanin (p < 0.01), anti-thyroid peroxidase (anti-TPO) (p < 0.001), anti-thyroglobulin (anti-Tg) (p < 0.001), and body mass index (BMI) (p < 0.05). The two groups were comparable in terms of spexin, free triiodothyronine-3 (fT3), fT4, thyroid-stimulating hormone (TSH) levels, and homeostatic model assessment for insulin resistance (HOMA-IR). Galanin and kisspeptin were seen to have a positive correlation (p < 0.01; r = 0.786).

CONCLUSIONS

Euthyroid women with HT were found to have higher levels of kisspeptin and galanin. These results imply that kisspeptin and galanin may be linked to the pathogenesis of hypothyroidism, and as a result, we believe that these markers may be beneficial in the early detection and treatment of HT patients.

The Effect of Exercise on Spexin and Follistatin in Elderly Individuals

BACKGROUND

In adipose tissue-muscle crosstalk mechanisms, the interaction of adipokines and myokines is known to be critical for maintaining the body's metabolic balance in age-related metabolic disorders. The aim of the study investigate the effects of 12 weeks of aerobic and resistance exercise training on spexin and follistatin and their relationship with each other.

METHODS

This study was a multicentre, randomized controlled study conducted at two assisted living facilities with participants aged ≥ 65. Among the 66 subjects, 33 were allocated to the exercise group (E) and 33 to the control group (C). The exercise group was administered 50 min of exercise by expert physiotherapists 1 day a week for 12 weeks. Participants in the intervention groups performed exercise assignments two extra days a week, tailored to their specific circumstances and supervised by the institution's physiotherapists. Spexin, follistatin and measurements of metabolic syndrome parameters were performed at the beginning and after 12 weeks.

RESULTS

The mean age of the 62 participants who completed the study (E n = 31, C n = 31) was 73.25 ± 6.44 years, and 62.9% were female. While spexin (E = 1090.94 ± 533.66, C = 1142.91 ± 550.68 pg/mL, p > 0.05) and follistatin (E = 50.52 ± 24.35, C = 50.00 ± 23.52 ng/mL, p > 0.05) values were similar in the two groups at baseline, the values of spexin (E = 1311.32 ± 513.66, C = 1033.27 ± 486.48, p < 0.0001; η2 = 0.387) and follistatin (E = 64.79 ± 32.35, C = 48.16 ± 26.27, p < 0.0001; η2 = 0.267) in the exercise group were higher than in the control group at week 12. At the 12th week, neck circumference (38.32 ± 3.41, 37.16 ± 3.15, p = 0.002), waist circumference (102.64 ± 13.38, 98.54 ± 14.47, p < 0.0001), hip circumference (105.70 ± 15.43, 102.93 ± 13.48, p < 0.0001), body fat mass (22.69 ± 7.39, 20.45 ± 6.22, p < 0.0001) and systolic and diastolic blood pressure (137.19 ± 13.80, 124.9 ± 15.18, p = 0.0001, 77.38 ± 12.10, 72.61 ± 9.26, p = 0.043) decreased, and body muscle mass (46.32 ± 8.43, 49.03 ± 8.58, p < 0.0001) increased in the exercise group compared to baseline. A correlation was observed between the change in follistatin level and the change in spexin level (r = 0.438, p = 0.001). A negative correlation was found between the amount of decrease in body fat mass and the decrease in spexin level (r = -0.380, p = 0.005). A positive correlation was found between the increase in body muscle mass and the increase in spexin and follistatin (r = 0.431, p = 0.001; r = 0.490, p < 0.0001, respectively).

CONCLUSIONS

It was found that spexin, which provides metabolic homeostasis, and follistatin, which expresses the increase in muscle mass, increased with the implementation of a 12-week aerobic and resistance exercise program in elderly individuals, and these increases were found to be associated with each other.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT05251597.

Immunohistochemical investigation of transient receptor potential melastatin-2 and spexin immunoreactivity in atopic dermatitis and mycosis fungoides

BACKGROUND

Atopic dermatitis (AD) is a chronic, pruritic, and inflammatory dermatosis seen in individuals with an atopic predisposition. This study aimed to examine the immunoreactivity of spexin and TRPM2 in skin samples from patients with AD and MF lesions using immunohistochemical methods.

MATERIALS AND METHODS

The study utilized a total of 60 skin samples, comprising 20 from AD patients, 20 from MF patients, and 20 from control subjects. Skin samples from patients diagnosed with other dermatological diseases, malignancies, and diabetes mellitus were excluded from the study. During staining, the prevalence (0.1: <25%, 0.4: 26-50%, 0.6: 51-75%, 0.9: 76-100%) and intensity (0: none, + 0.5: very low, + 1: low, + 2: moderate, + 3: intense) of immunoreactivity were used as criteria to establish a histo-score. Calculations employed the formula histo-score = prevalence x intensity.

RESULTS

Statistically significant higher spexin histoscores were observed in both the AD and MF patient groups compared to the control group (1.30 ± 0.46, 1.04 ± 0.29, and 0.20 ± 0.07, respectively; p = 0.000). Similarly, TRPM2 histoscores were significantly higher in the AD and MF patient groups compared to the control group (1.12 ± 0.28, 1.02 ± 0.30, and 0.20 ± 0.07, respectively; p = 0.000).

CONCLUSION

It is hypothesized that the increase in the neuropeptide spexin in both AD and MF is triggered by inflammation and contributes to itching mechanisms via galanin receptors. TRPM2, an ion channel, is speculated to be a marker of Reactive Oxygen Species (ROS) in chronic inflammatory dermatoses like AD, but it may not serve as a potential biomarker for distinguishing chronic inflammatory dermatoses from MF.

Systemic and tissue-specific spexin response to acute treadmill exercise in rats

Spexin (SPX) is a 14-amino-acid peptide that plays an important role in the regulation of metabolism and energy homeostasis. It is well known that a variety of bioactive molecules released into the circulation by organs and tissues in response to acute and chronic exercise, known as exerkines, mediate the benefits of exercise by improving metabolic health. However, it is unclear whether acute exercise affects SPX levels in the circulation and peripheral tissues. This study aimed to determine whether acute treadmill exercise induces plasma SPX levels, as well as mRNA expression and immunostaining of SPX in skeletal muscle, adipose tissue, and liver. Male Sprague Dawley rats were divided into sedentary and acute exercise groups. Plasma, soleus (SOL), extensor digitorum longus (EDL), adipose tissue, and liver samples were collected at six time points (0, 1, 3, 6, 12, and 24 h) following 60 min of acute treadmill exercise at a speed of 25 m/min and 0 % grade. Acute exercise increased plasma SPX levels and induced mRNA expression of Spx in the SOL, EDL, and liver. Immunohistochemical analysis demonstrated that acute exercise led to a decrease in SPX immunostaining in the liver. Taken together, these findings suggest that SPX increases in response to acute exercise as a potential exerkine candidate, and the liver may be one of the sources of acute exercise-induced plasma SPX levels in rats. However, a comprehensive analysis is needed to fully elucidate the systemic response of SPX to acute exercise, as well as the tissue from which SPX is secreted.

Exercise training and spexin ameliorate thyroid changes in obese type 2 diabetic rats: the possible interlaying mechanisms

Thyroid dysfunction and diabetes mellitus are prevalent endocrine disorders that often coexist and influence each other. The role of spexin (SPX) in diabetes and obesity is well documented, but its connection to thyroid function is less understood. This study investigates the influence of exercise (EX) and SPX on thyroid hypofunction in obese type 2 diabetic rats. Rats were divided into normal control, obese diabetic sedentary, obese diabetic EX, and obese diabetic SPX groups, with subdivisions for M871 and HT-2157 treatment in the latter two groups. High-fat diet together with streptozotocin (STZ) injection induced obesity and diabetes. The EX group underwent swimming, and the SPX group received SPX injections for 8 wk. Results showed significant improvements in thyroid function and metabolic, oxidative, and inflammatory states with EX and SPX treatment. The study also explored the involvement of galanin receptor isoforms (GALR)2/3 in SPX effects on thyroid function. Blocking GALR2/3 receptors partially attenuated the beneficial effects, indicating their interaction. These findings underscore the importance of EX and SPX in modulating thyroid function in obesity and diabetes. Comprehending this interplay could enable the development of new treatment approaches for thyroid disorders associated with obese type 2 diabetes. Additional research is necessary to clarify the exact mechanisms connecting SPX, EX activity, and thyroid function.NEW & NOTEWORTHY This study proves, for the first time, the beneficial effects of SPX on thyroid dysfunction in obese diabetic rats and suggests that SPX mediates the EX effect on thyroid gland and exerts its effect mainly via GALR2.

Normalization of Spexin Levels in Patients with Obesity Submitted to Bariatric Surgery

PURPOSE

Spexin is expressed by white fat tissue and other endocrine organs. A negative correlation between spexin and gluco-lipidic metabolism, energy homeostasis, and food intake has been reported. The objectives of this study are (1) to compare spexin levels between patients with obesity (study group) and normal-weight subjects (control group); (2) to evaluate spexin levels after bariatric surgery; and (3) to identify a correlation between spexin and weight loss/metabolic profile of patients with obesity.

MATERIALS AND METHODS

We examined 53 patients with obesity (mean BMI 48.5 ± 9.4 kg/m2) who underwent bariatric surgery, compared to 55 normal-weight subjects. Serum spexin levels were assessed at baseline (study and control group) and at 3 and 6 months after surgery in patients with obesity.

RESULTS

Spexin at baseline was significantly lower in the study group (p < 0.0001). At 3 and 6 months after bariatric surgery, spexin significantly increased compared to pre-surgical levels (p < 0.001) reaching control group levels (p = 0.08) at 6 months. In patients with obesity, pre-surgical spexin was similar in patients with and without comorbidities. No correlation between spexin and C-reactive protein (p = 0.8) and HOMA index (p = 0.5) was found. A significant negative correlation between age and pre-surgical spexin was observed (p = 0.03). At multivariable analysis, no correlation between Δ spexin and pre-surgery BMI, HOMA index, age, and 6-month TWL% was found.

CONCLUSION

This study demonstrates that patients with obesity have significantly lower spexin levels than healthy subjects. After surgery, spexin levels of the study group become similar to those observed in the normal-weight group.

Role of Spexin in White Adipose Tissue Thermogenesis under Basal and Cold-Stimulated Conditions

Spexin (SPX) is a novel adipokine that plays an emerging role in metabolic diseases due to its involvement in carbohydrate homeostasis, weight loss, appetite control, and gastrointestinal movement, among others. In obese patients, SPX plasma levels are reduced. Little is known about the relationship between SPX and white adipose tissue (WAT) thermogenesis. Therefore, the aim of the present study was to evaluate the role of SPX in this process. C57BL/6J male mice were treated or not with SPX for ten days. On day 3, mice were randomly divided into two groups: one kept at room temperature and the other kept at cold temperature (4 °C). Caloric intake and body weight were recorded daily. At the end of the protocol, plasma, abdominal (epididymal), subcutaneous (inguinal), and brown AT (EAT, IAT, and BAT, respectively) depots were collected for measurements. We found that SPX treatment reduced Uncoupling protein 1 levels in WAT under both basal and cold conditions. SPX also reduced cox8b and pgc1α mRNA levels and mitochondrial DNA, principally in IAT. SPX did not modulate the number of beige precursors. SPX decreased spx levels in IAT depots and galr2 in WAT depots. No differences were observed in the BAT depots. In conclusion, we showed, for the first time, that SPX treatment in vivo reduced the thermogenic process in subcutaneous and abdominal AT, being more evident under cold stimulation.

An update on galanin and spexin and their potential for the treatment of type 2 diabetes and related metabolic disorders

Spexin (SPX) and galanin (GAL) are two neuropeptides widely expressed in the central nervous system as well as within peripheral tissues in humans and other species. SPX and GAL mediate their biological actions through binding and activation of galanin receptors (GALR), namely GALR1, GALR2 and GLAR3. GAL appears to trigger all three galanin receptors, whereas SPX interacts more specifically with GALR2 and GLAR3. Whilst the biological effects of GAL have been well-described over the years, in-depth knowledge of physiological action profile of SPX is still in its preliminary stages. However, it is recognised that both peptides play a significant role in modulating overall energy homeostasis, suggesting possible therapeutically exploitable benefits in diseases such as obesity and type 2 diabetes mellitus. Accordingly, although both peptides activate GALR's, it appears GAL may be more useful for the treatment of eating disorders such as anorexia and bulimia, whereas SPX may find therapeutic application for obesity and obesity-driven forms of diabetes. This short narrative review aims to provide an up-to-date account of SPX and GAL biology together with putative approaches on exploiting these peptides for the treatment of metabolic disorders.

Cord Blood Spexin Level in Mothers with Obesity-Forecast of Future Obesity?

Spexin (SPX) is a peptide that plays an important role in the regulation of food intake and body weight (BW) by the effect on carbohydrate-lipid metabolism. However, the role of SPX in fetal life, in children, and in adolescent metabolism is limited. Therefore, we decided to check whether obesity affects the concentration of SPX in the mother's peripheral blood (MB) and umbilical cord blood (UCB). Using MB and UCB sera on the day of delivery obtained from 48 women (24 non-obese and 24 obese) and commercially available Elisa kits and colorimetric assays, we determined changes in SPX and the relationship between SPX concentration and other metabolic and anthropometric markers (body weight and BMI) on the day of delivery and in children at the age of 36 months. We found lower concentrations of SPX in MB (p < 0.05) and UCB (p < 0.01) derived from obese women (BMI > 30) and a moderate linear correlation (r = 0.4429; p < 0.01) between SPX concentrations in MB and UCB. We also noted that the concentration of SPX is not correlated with the child's body weight on the day of birth (r = -0.0128). However, there is a relationship between SPX at birth and body weight at 3 years of age (r = -0.3219; p < 0.05). Based on the obtained results, it can be assumed that spexin is one of the factors modulating the child's metabolism already in the fetal period and can be considered a potential marker of future predisposition to obesity. However, confirmation of this thesis requires additional research.

Recent Advances in the Treatment of Insulin Resistance Targeting Molecular and Metabolic Pathways: Fighting a Losing Battle?

Diabetes Mellitus (DM) is amongst the most notable causes of years of life lost worldwide and its prevalence increases perpetually. The disease is characterized as multisystemic dysfunctions attributed to hyperglycemia resulting directly from insulin resistance (IR), inadequate insulin secretion, or enormous glucagon secretion. Insulin is a highly anabolic peptide hormone that regulates blood glucose levels by hastening cellular glucose uptake as well as controlling carbohydrate, protein, and lipid metabolism. In the course of Type 2 Diabetes Mellitus (T2DM), which accounts for nearly 90% of all cases of diabetes, the insulin response is inadequate, and this condition is defined as Insulin Resistance. IR sequela include, but are not limited to, hyperglycemia, cardiovascular system impairment, chronic inflammation, disbalance in oxidative stress status, and metabolic syndrome occurrence. Despite the substantial progress in understanding the molecular and metabolic pathways accounting for injurious effects of IR towards multiple body organs, IR still is recognized as a ferocious enigma. The number of widely available therapeutic approaches is growing, however, the demand for precise, safe, and effective therapy is also increasing. A literature search was carried out using the MEDLINE/PubMed, Google Scholar, SCOPUS and Clinical Trials Registry databases with a combination of keywords and MeSH terms, and papers published from February 2021 to March 2022 were selected as recently published papers. This review paper aims to provide critical, concise, but comprehensive insights into the advances in the treatment of IR that were achieved in the last months.