Decreased plasma neuregulin 4 levels are associated with peripheral neuropathy in Chinese patients with newly diagnosed type 2 diabetes: A cross-sectional study

Low circulating levels of neuregulin 4 as a potential biomarker associated with the severity and prognosis of obesity-related metabolic diseases: a systematic review

BACKGROUND

Neuregulin 4 (Nrg4) is a brown adipose tissue-derived adipokine that greatly affects systemic metabolism and improves metabolic derangements. Although abnormal circulating levels of Nrg4 are common in obesity, it remains elusive whether low or elevated levels of this batokine are associated with the onset of metabolic diseases.

AIM

To assess Nrg4 levels and its role as a feasible biomarker to predict the severity of obesity, gestational diabetes mellitus (GDM), type 2 diabetes mellitus (T2DM), non-alcoholic fatty liver disease (NAFLD), and cardiovascular diseases (CVD).

METHODS

A search for relevant studies was performed systematically using prominent search engines, including PubMed, Google Scholar, and Embase, by following PRISMA guidelines.

RESULTS

Ample clinical evidence reported low serum/plasma levels of Nrg4 in obesity and these were inversely proportional to the indices of metabolic syndrome, including body mass index, waist circumference, triglycerides, fasting plasma glucose, and homoeostatic model assessment for insulin resistance as well as high-sensitivity C-reactive protein. Low circulating Nrg4 levels may aid in the prediction of morbid obesity, and subsequent GDM, T2DM, NAFLD, and CVD.

CONCLUSION

Current clinical evidence emphasizes that the circulating levels of Nrg4 are decreased in morbid obesity, and it also highlights that Nrg4 May serve as a potential prognostic biomarker for obesity-related metabolic diseases.

The role of novel inflammation-associated biomarkers in diabetic peripheral neuropathy

Diabetic neuropathy is one of the commonest complications of diabetes mellitus. Its most frequent form is diabetic peripheral neuropathy (DPN). Currently, there is no established and widely used biomarker for diagnosis and clinical staging of DPN. There is accumulating evidence that low-grade systemic inflammation is a key element in its pathogenesis. In this context, several clinical studies have so far identified potential biomarkers of DPN. These studies have enrolled both subjects with type 1 diabetes mellitus (T1DM) and subjects with type 2 diabetes mellitus (T2DM), including children with T1DM and elderly T2DM subjects. They have also evaluated participants with prediabetes. Potential biomarkers include a wide spectrum of cytokines, chemokines and immune receptors, notably interleukins (IL), mostly IL-1, IL-6 or IL-10, as well as mediators of the tumour necrosis factor-α (TNF-α) related pathway. Cell-ratios, such as neurtrophil-to-lymphocyte ratio (NLR), have yielded promising results as well. Other works have focused on adipokines and identified several signalling molecules (adiponectin, neuregulin 4, isthmin-1 and omentin) as promising biomarkers of DPN. Finally, epigenetic biomarkers have been investigated. Further experience is being gathered with the use of biomarkers in specific age groups and in the discrimination between painless and painful DPN. Prospective studies appear promising in monitoring of DPN progression, but experience is rather limited. Finally, certain cut-off values have been proposed for DPN screening, but these need confirmation. Future large-scale studies are now required to validate biomarkers and to investigate their potential clinical utility.

The Potential of Neuregulin 4 as a Novel Biomarker and Therapeutic Agent for Vascular Complications in Type 2 Diabetes Mellitus

Neuregulin 4 (Nrg4), a novel adipokine produced primarily by brown adipose tissue (BAT), has been functionally characterized to exert beneficial effects on modulating energy homeostasis and glucolipid metabolism, and is closely associated with the development and progression of obesity and obesity-associated metabolic diseases, such as type 2 diabetes mellitus (T2DM) and cardiovascular diseases. Recently, there has been a growing focus on the relationship between circulating Nrg4 levels and T2DM-related vascular complications. In this review, we discussed the known and potential roles of Nrg4 in various physiological and pathological processes, and its association with vascular complications in T2DM, in the aim of finding a potential biomarker recommended for the clinical diagnosis, prognosis and follow-up of T2DM patients at high risk of developing vascular complications as well as providing new therapeutic approaches.

Corneal nerve loss in adolescents with obesity and acanthosis nigricans

BACKGROUND/AIM

Obesity and related metabolic abnormalities in adults are associated with peripheral neuropathy. Acanthosis nigricans (AN) is associated with insulin resistance, fatty liver, hyperlipidemia and glucose intolerance, all of which are risk factors for neuropathy. The aim of this study was to investigate if obese adolescents with AN have evidence of small nerve fiber damage.

MATERIAL AND METHODS

Adolescents with obesity with and without AN underwent body composition analysis, assessment of vibration perception threshold (VPT), monofilament sensitivity and corneal confocal microscopy (CCM) to quantify corneal nerve fiber density (CNFD), branch density (CNBD), length (CNFL) and inferior whorl length (IWL).

RESULTS

Forty-six participants with obesity with (n = 31) and without (n = 15) AN aged 15(14-17) years were compared to 20 healthy controls aged 13(12-14) years. There was no difference in VPT, monofilament sensitivity and CCM measures between adolescents with obesity and controls. However, adolescents with AN had a significantly higher weight (P = 0.022), fat% (P = 0.029) and fat-muscle ratio (P = 0.012) with a lower CNFD (P = 0.045) compared to those with obesity without AN.

CONCLUSION

Adolescents with obesity and acanthosis nigricans have a higher fat mass and small nerve fibre loss, indicative of a sub-clinical neuropathy.

Advances in Exosome-Based Therapies for the Repair of Peripheral Nerve Injuries

Peripheral nerve injuries (PNIs) are the term used to describe injuries that occur to the nerve fibers of the peripheral nervous system (PNS). Such injuries may be caused by trauma, infection, or aberrant immunological response. Although the peripheral nervous system has a limited capacity for self-repair, in cases of severe damage, this process is either interrupted entirely or is only partially completed. The evaluation of variables that promote the repair of peripheral nerves has consistently been a focal point. Exosomes are a subtype of extracellular vesicles that originate from cellular sources and possess abundant proteins, lipids, and nucleic acids, play a critical role in facilitating intercellular communication. Due to their modifiable composition, they possess exceptional capabilities as carriers for therapeutic compounds, including but not limited to mRNAs or microRNAs. Exosome-based therapies have gained significant attention in the treatment of several nervous system diseases due to their advantageous properties, such as low toxicity, high stability, and limited immune system activation. The objective of this review article is to provide an overview of exosome-based treatments that have been developed in recent years for a range of PNIs, including nerve trauma, diabetic neuropathy, amyotrophic lateral sclerosis (ALS), glaucoma, and Guillain-Barre syndrome (GBS). It was concluded that exosomes could provide favorable results in the improvement of peripheral PNIs by facilitating the transfer of regenerative factors. The development of bioengineered exosome therapy for PNIs should be given more attention to enhance the efficacy of exosome treatment for PNIs.

The journey towards physiology and pathology: Tracing the path of neuregulin 4

Neuregulin 4 (Nrg4), an epidermal growth factor (EGF) family member, can bind to and activate the ErbB4 receptor tyrosine kinase. Nrg4 has five different isoforms by alternative splicing and performs a wide variety of functions. Nrg4 is involved in a spectrum of physiological processes including neurobiogenesis, lipid metabolism, glucose metabolism, thermogenesis, and angiogenesis. In pathological processes, Nrg4 inhibits inflammatory factor levels and suppresses apoptosis in inflammatory diseases. In addition, Nrg4 could ameliorate obesity, insulin resistance, and cardiovascular diseases. Furthermore, Nrg4 improves non-alcoholic fatty liver disease (NAFLD) by promoting autophagy, improving lipid metabolism, and inhibiting cell death of hepatocytes. Besides, Nrg4 is closely related to the development of cancer, hyperthyroidism, and some other diseases. Therefore, elucidation of the functional role and mechanisms of Nrg4 will provide a clearer view of the therapeutic potential and possible risks of Nrg4.

The Role of Adipokines and Myokines in the Pathogenesis of Different Obesity Phenotypes-New Perspectives

Obesity is a characteristic disease of the twenty-first century that is affecting an increasing percentage of society. Obesity expresses itself in different phenotypes: normal-weight obesity (NWO), metabolically obese normal-weight (MONW), metabolically healthy obesity (MHO), and metabolically unhealthy obesity (MUO). A range of pathophysiological mechanisms underlie the occurrence of obesity, including inflammation, oxidative stress, adipokine secretion, and other processes related to the pathophysiology of adipose tissue (AT). Body mass index (BMI) is the key indicator in the diagnosis of obesity; however, in the case of the NWO and MONW phenotypes, the metabolic disturbances are present despite BMI being within the normal range. On the other hand, MHO subjects with elevated BMI values do not present metabolic abnormalities. The MUO phenotype involves both a high BMI value and an abnormal metabolic profile. In this regard, attention has been focused on the variety of molecules produced by AT and their role in the development of obesity. Nesfatin-1, neuregulin 4, myonectin, irisin, and brain-derived neurotrophic factor (BDNF) all seem to have protective effects against obesity. The primary mechanism underlying the action of nesfatin-1 involves an increase in insulin sensitivity and reduced food intake. Neuregulin 4 sup-presses lipogenesis, decreases lipid accumulation, and reduces chronic low-grade inflammation. Myonectin lowers the amount of fatty acids in the bloodstream by increasing their absorption in the liver and AT. Irisin stimulates the browning of white adipose tissue (WAT) and consequently in-creases energy expenditure, additionally regulating glucose metabolism. Another molecule, BDNF, has anorexigenic effects. Decorin protects against the development of hyperglycemia, but may also contribute to proinflammatory processes. Similar effects are shown in the case of visfatin and chemerin, which may predispose to obesity. Visfatin increases adipogenesis, causes cholesterol accumulation in macrophages, and contributes to the development of glucose intolerance. Chemerin induces angiogenesis, which promotes the expansion of AT. This review aims to discuss the role of adipokines and myokines in the pathogenesis of the different obesity phenotypes.

Study of neuregulin-4 levels in newly diagnosed type 2 diabetes mellitus

Background

Neuregulin-4 is a recently recognized adipokine acting as ligands to tyrosine kinases receptor of the Erb B family. This adipose tissue augmented endocrine factor participates in the modulation of lipid and glucose metabolism and energy homeostasis. This novel adipokine is associated with insulin resistance, dyslipidemia, obesity, oxidative stress, and inflammation.

Objective

The study aimed to compare plasma levels of neuregulin-4 in newly diagnosed type 2 diabetes mellitus as compared to matched controls and to correlate with glycemic and lipid parameters.

Materials and Methods

100 newly diagnosed T2DM patients and 100 age, sex, and BMI-matched controls after fulfilling all exclusion and inclusion criteria were included in the study. Fasting and postprandial blood glucose levels, glycated hemoglobin (HbA1c), and fasting plasma insulin levels were measured in both cases and controls. HOMA-IR values in both groups were calculated using fasting glucose and insulin levels.

Results

Mean levels of plasma neuregulin-4(pg/mL) in newly diagnosed T2DM were 7949.76 ± 949.76) pg/ml, which was significantly lower as compared to 9143 ±949.76) pg/ml in the control group (P-value <.0001). In the present study, a significant negative correlation was seen between plasma neuregulin-4 (pg/mL) with fasting blood sugar, postprandial blood sugar, HbA1C, and HOMA-IR with a correlation coefficient of -0.303, -0.416, -0.433, and -0.514, respectively. Moreover, a significant positive correlation was seen between plasma neuregulin-4 (pg/mL) with HDL with a correlation coefficient of 0.216. A significant negative correlation was seen between plasma neuregulin-4 (pg/mL) and LDL, with a correlation coefficient -0.208.

Conclusion

Neuregulin levels are significantly lower in diabetics as compared to controls. There levels correlated inversely with HbA1C and HOMA IR.

Evaluation of Nrg4 and thiol/disulfide homeostasis in patients with GDM

BACKGROUND

In this study, we aimed to evaluate the role of neuregulin4 (Nrg4) in the etiopathogenesis of gestational diabetes mellitus (GDM) and thiol/disulfide homeostasis as an indicator of oxidative stress.

METHODS

This prospective, case-control study included 34 women with diabetes and 34 healthy pregnant women who applied between January 2017 and January 2020. Levels of native and total thiol, disulfide and Nrg4 were measured in both diabetes mellitus and healthy pregnant groups.

RESULTS

When compared to the control group, the serum neuregulin4 levels in the diabetes group were considerably lower (3.22 ± 2.16 vs. 4.55 ± 0.96, p < 0.001). Native thiol (292.67 ± 43.65 vs. 366.40 ± 51.28; p < 0.001), total thiol (388.60 ± 46.60 vs. 414.52 ± 54.19; p < 0.001) levels and native thiol/total thiol ratio (75.51 ± 8.95 vs. 88.35 ± 3.54; p < 0.001) were lower in diabetes group compared to control group. Disulfide level (47.96 ± 19.52 vs. 24.06 ± 7.69) and disulfide/native thiol (17.13 ± 8.03, vs. 6.67 ± 2.30) and disulfide/total thiol (12.24 ± 4.47 vs. 5.82 ± 1.77) ratios were higher in diabetes group (all p < 0.001).

CONCLUSIONS

We suggested that decreased Nrg4 level and impaired oxidative stress parameters may be related with the increased risk of diabetes. However, we did not found a correlation between the Nrg4 and oxidative stress parameters.

Diagnostic Value of the Combined Measurement of Serum HCY and NRG4 in Type 2 Diabetes Mellitus with Early Complicating Diabetic Nephropathy

PURPOSE

This study aimed to investigate the value of combined detection of HCY and NRG4 in the diagnosis of early diabetic kidney disease (DKD) and to explore the association between the ratio of HCY/NRG4 and DKD.

METHODS

A total of 140 diabetic patients and 43 healthy people were prospectively enrolled. The plasma HCY level, NRG4 level and HCY/NRG4 of them were measured to compare their differences and analyze the correlation with DKD. The independent influencing factors of patients with DKD were screened, and the nomograph of DKD occurrence was constructed.

RESULTS

The levels of HCY and HCY/NRG4 in diabetic patients were significantly increased, while the level of NRG4 was significantly decreased (p < 0.01). The AUCs of HCY/NRG4 predicted for DKD were 0.961. HCY/NRG4 and the course of DM were independent risk factors for DKD. A predictive nomograph of DKD was constructed, and decision curve analysis (DCA) showed good clinical application value. HCY/NRG4 was positively correlated with Scr, UACR, TG, UA, BUN, TCHOL and LDL and negatively correlated with eGFR and HDL (p < 0.05).

CONCLUSIONS

The level of HCY and NRG4 is closely related to the severity of DM, and combined detection of HCY/NRG4 can identify patients with DKD at an early stage.

Correlation of asprosin and Nrg-4 with type 2 diabetes Mellitus Complicated with Coronary Heart Disease and the Diagnostic Value

PURPOSE

Asprosin is a newly discovered adipose factor secreted by white fat, which is involved in glucose metabolism and inflammation. Neuregulin-4 (Nrg-4) is a new adipose factor released from brown adipose tissue and is considered to play an important role in metabolism. This study aims to explore the association between serum Asprosin, Nrg-4 level and coronary heart disease(CHD) in patients with type 2 diabetes mellitus(T2DM) and the diagnostic value.

PATIENTS AND METHODS

157 patients with T2DM were enrolled from Affiliated Hospital of Chengde Medical University between December 2020 to July 2021. These patients were divided into T2DM without CHD group (T2DM-0, n = 80) and T2DM with CHD (T2DM-CHD, n = 77). Serum Asprosin and Nrg-4 expression was detected by enzyme-linked immunosorbent assay, and the correlations between Asprosin or Nrg-4 and clinical and biochemical indicators were analyzed. A receiver operating characteristics curve analysis and area under the curve (AUC) were used to evaluate diagnostic accuracy.

RESULTS

Serum Asprosin level of the T2DM-CHD group were significantly higher and Nrg-4 level significantly lower than those of the T2DM-0 group.Spearman correlation analysis showed that serum Asprosin levels were significantly positively correlated with diabetes course,history of hypertension, fasting plasma glucose(FPG), glycosylated hemoglobin A1c(HbA1C), triglycerides(TG),triglyceride glucose index(TyG index) and urea, and negatively correlated with ALT (all p < 0.05). Nrg-4 was negatively correlated with history of hypertension, body mass index(BMI), FPG, HbA1C, TG, and TyG indexes (all p < 0.05), and positively correlated with high-density lipoprotein cholesterol(HDL-C)(p < 0.05).Logistic regression analysis showed that after adjusting potential confounders, Asprosin was a risk factor for diabetes mellitus, Nrg-4 was a protective factor.The AUC of Asprosin for diagnosing T2DM-CHD was 0.671 (95% confidence interval [CI] 0.584-0.759), and the AUC of the Nrg4 index for diagnosing T2DM-CHD was 0.772 (95% CI 0.700-0.844). The AUC of Asprosin and Nrg-4 for the combined diagnosis of T2DM-CHD was 0.796 (95% CI 0.726-0.864).

CONCLUSION

Asprosin and Nrg-4 may be novel diagnostic biomarkers for T2DM with CHD, as they effectively improved the diagnostic accuracy for T2DM-CHD.

Neuregulin 4 as a novel adipokine in energy metabolism

Adipose tissue has been shown to play a key role in energy metabolism and it has been shown to regulate metabolic homeostasis through the secretion of adipokines. Neuregulin 4 (Nrg4), a novel adipokine secreted mainly by brown adipose tissue (BAT), has recently been characterized as having an important effect on the regulation of energy homeostasis and glucolipid metabolism. Nrg4 can modulate BAT-related thermogenesis by increasing sympathetic innervation of adipose tissue and therefore has potential metabolic benefits. Nrg4 improves metabolic dysregulation in various metabolic diseases such as insulin resistance, obesity, non-alcoholic fatty liver disease, and diabetes through several mechanisms such as anti-inflammation, autophagy regulation, pro-angiogenesis, and lipid metabolism normalization. However, inconsistent findings are found regarding the effects of Nrg4 on metabolic diseases in clinical settings, and this heterogeneity needs to be further clarified by future studies. The potential metabolic protective effect of Nrg4 suggests that it may be a promising endocrine therapeutic target.

Neuregulin-4 attenuates diabetic cardiomyopathy by regulating autophagy via the AMPK/mTOR signalling pathway

Background

Diabetic cardiomyopathy is characterized by left ventricle dysfunction, cardiomyocyte apoptosis, and interstitial fibrosis and is a serious complication of diabetes mellitus (DM). Autophagy is a mechanism that is essential for maintaining normal heart morphology and function, and its dysregulation can produce pathological effects on diabetic hearts. Neuregulin-4 (Nrg4) is an adipokine that exerts protective effects against metabolic disorders and insulin resistance. The aim of this study was to explore whether Nrg4 could ameliorate DM-induced myocardial injury by regulating autophagy.

Methods

Four weeks after the establishment of a model of type 1 diabetes in mice, the mice received Nrg4 treatment (with or without an autophagy inhibitor) for another 4 weeks. The cardiac functions, histological structures and cardiomyocyte apoptosis were investigated. Autophagy-related protein levels along with related signalling pathways that regulate autophagy were evaluated. In addition, the effects of Nrg4 on autophagy were also determined in cultured primary cardiomyocytes.

Results

Nrg4 alleviated myocardial injury both in vivo and in vitro. The autophagy level was decreased in type 1 diabetic mice, and Nrg4 intervention reactivated autophagy. Furthermore, Nrg4 intervention was found to activate autophagy via the AMPK/mTOR signalling pathway. Moreover, when autophagy was suppressed or the AMPK/mTOR pathway was inhibited, the beneficial effects of Nrg4 were diminished.

Conclusion

Nrg4 intervention attenuated diabetic cardiomyopathy by promoting autophagy in type 1 diabetic mice. Additionally, Nrg4 induced autophagy via the AMPK/mTOR signalling pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01643-0.

Age Worsens the Cognitive Phenotype in Mice Carrying the Thr92Ala-DIO2 Polymorphism

The Thr92Ala-Dio2 polymorphism has been associated with reduced cognition in 2-month-old male mice and increased risk for cognitive impairment and Alzheimer's disease in African Americans. This has been attributed to reduced thyroid hormone (TH) signaling and endoplasmic reticulum (ER) stress in the brain. Here we studied the Thr92Ala-Dio2 mouse model and saw that older male mice (7-8-month-old) exhibited a more severe cognition impairment, which extended to different aspects of declarative and working memories. A similar phenotype was observed in 4-5-month-old female mice. There were no structural alterations in the prefrontal cortex (PFC) and hippocampus of the Thr92Ala-Dio2 mouse. Nonetheless, in both male and female PFC, there was an enrichment in genes associated with TH-dependent processes, ER stress, and Golgi apparatus, while in the hippocampus there was additional enrichment in genes associated with inflammation and apoptosis. Reduced TH signaling remains a key mechanism of disease given that short-term treatment with L-T3 rescued the cognitive phenotype observed in males and females. We conclude that in mice, age is an additional risk factor for cognitive impairment associated with the Thr92Ala-Dio2 polymorphism. In addition to reduced TH signaling, ER-stress, and involvement of the Golgi apparatus, hippocampal inflammation and apoptosis were identified as potentially important mechanisms of a disease.

MicroRNA-124 modulates neuroinflammation in acute methanol poisoning rats via targeting Krüppel-like factor-6

Microglia activation-stimulated neuroinflammation exerts functionally in neurodegenerative diseases like brain injury. Acute methanol poisoning (AMP) is a crucial cause of death and morbidity that possibly leads to neuroinflammation. Studies have manifested that miRNAs can modulate microglia activation to mediate neuroinflammation. Nevertheless, the role of miR-124 in AMP-stimulated neuroinflammation is uncertain. This research was to explore the action of miR-124 in AMP-stimulated neuroinflammation and its molecular mechanism. The study findings indicated that AMP accelerated microglia activation and stimulated inflammation and oxidative stress in brain tissue of rats. MiR-124 expression was lowered in AMP rats, while KLF6 expression was elevated. Elevated miR-124 or repressed KLF6 increased the number of CD206⁺ cells and decreased the number of CD68⁺ cells, as well as restrained inflammation and NF-κB phosphorylation and induced superoxide dismutase, Nrf2/HO-1, and M2 polarization. MiR-124 modulated microglia activation via targeting KLF6. AMP repressed neuronal viability and enhanced neuronal apoptosis. Suppression of miR-124 further promoted AMP-induced damage to neurons, while inhibition of KLF6 turned around this phenomenon. Anyway, our study demonstrated that miR-124 accelerates M2 polarization via targeting KLF6 to ameliorate AMP-stimulated neuronal damage.

Decreased expression of ErbB2 on left ventricular epicardial cells in patients with diabetes mellitus

We investigated the cell surface expression of ErbB receptors on left ventricular (LV) epicardial endothelial cells and CD105⁺ cells obtained from cardiac biopsies of patients undergoing coronary artery bypass grafting surgery (CABG). Endothelial cells and CD105⁺ non-endothelial cells were freshly isolated from LV epicardial biopsies obtained from 15 subjects with diabetes mellitus (DM) and 8 controls. The expression of ErbB receptors was examined using flow cytometry. We found that diabetes mellitus (DM) and high levels of hemoglobin A1C are associated with reduced expression of ErbB2. To determine if the expression of ErbB2 receptors is regulated by glucose levels, we examined the effect of high Glucose in human microvascular endothelial cells (HMEC-1) and CD105⁺ non-endothelial cells, using a novel flow cytometric approach to simultaneously determine the total level, cell surface expression, and phosphorylation of ErbB2. Incubation of cells in the presence of 25 mM d-glucose resulted in decreased cell surface but not total levels of ErbB2. The level of ErbB2 at the cell surface is controlled by disintegrin and metalloproteinase domain-containing protein 10 (ADAM10) that is expressed on LV epicardial cells. Inhibition of ADAM10 prevented the high glucose-dependent decrease in the cell surface expression of ErbB2. We suggest that high Glucose depresses ErbB receptor signaling in endothelial cells and cardiac progenitor cells via the promotion of ADAM10-dependent cleavage of ErbB2 at the cell surface, thus contributing to vascular dysfunction and adverse remodeling seen in diabetic patients.

Lower Visceral Fat Area in Patients with Type 2 Diabetic Peripheral Neuropathy

OBJECTIVE

There is preliminary evidence that visceral fat area (VFA) was associated with the presence of type 2 diabetic peripheral neuropathy (DPN) in the Korean population; however, no studies have reported the association in Chinese population. The purpose of this study was to explore the possible correlation of VFA with DPN in such a population.

METHODS

A total of 2498 hospitalized patients with type 2 diabetes mellitus (T2DM) undergone VFA measurement, and were divided into DPN group (n=900) and non-DPN group (n=1594). The association of VFA with the presence of DPN was evaluated by correlation and multiple logistic regression analyses, generalized additive model with a smooth curve fitting, and receiver operating characteristic (ROC) curve analysis.

RESULTS

The VFA was significantly lower in the DPN group than in the non-DPN group (P < 0.001). VFA was significantly and positively associated with sural nerve conduction velocity (SNCV) and amplitude potential (SNAP) and negatively associated with the presence of DPN (all P< 0.001); there was no significant difference in the curve fitting (P = 0.344). Multivariate logistic regression analysis showed that the risk of presence of DPN decreased progressively across the VFA quartiles (P for trend < 0.001) and was significantly lower in patients in the highest VFA quartile than in those in the lowest quartile (OR: 0.382, 95% CI 0.151-0.968, P< 0.001) after multivariate adjustment. The ROC analysis revealed that the best cut-off value of VFA for predicting the presence of DPN was 50.5cm² (sensitivity 84.40%; specificity 34.00%).

CONCLUSION

These results suggest that lower VFA level may be associated with increased risk of the presence of DPN in T2DM patients.

Paeoniflorin Effect of Schwann Cell-Derived Exosomes Ameliorates Dorsal Root Ganglion Neurons Apoptosis through IRE1α Pathway

Background

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes but its pathogenesis is not fully clarified. Endoplasmic reticulum (ER) stress has been confirmed to be involved in the development of DPN. Dorsal root ganglion neuron (DRGn) is the target cell of DPN injure in the peripheral neurons system. Schwann cell (SCs)-derived exosomes (SC-EXOs) can carry IRE1α signal transduction factors in ER stress to DRGn. The aim of this study is to investigate the effect of SC-EXOs treated with paeoniflorin (PF) on DRGn stimulated by high glucose.

Methods

SCs were divided into Control group (Control), 150 mM glucose group (HG), high osmotic pressure group (HOP), and low, middle, and high dose PF group (PF1, PF10, and PF100). Exosomes were obtained from SCs by ultracentrifugation and identified according to marker proteins, including CD63, Alix, Hsp70, and TSG101. ER stress initiating factor GRP78, the IRE1α pathway information transmission factor IRE1α, and the phosphorylation level of IRE1α were detected by Western blot, DRGn is divided into Control group (Control), 50 mM glucose group + Control exosomes group (HG + EXOs Control), 50 mM glucose group (HG), and 50 mM glucose group + administration exosomes group (HG + EXOs PF1, HG + EXOs PF10, and HG + EXOs PF100); ER morphology of primary DRGn was observed by using the transmission electron microscope, the level of DRGn apoptosis was analyzed by TUNEL, and the downstream proteins of ER stress including CHOP, XBP1S, JNK, and p-JNK in DRG and the expression of apoptosis-related proteins Bcl-2, Bax, Caspase-3, and Caspase-12 were measured by Western blot.

Results

Compared with the exosomes in the HG group, the exosomes after the intervention of PF can significantly reduce the expression of GRP78, IRE1α, and the phosphorylation level of IRE1α(P < 0.05); compared with the DRGn in the HG group, the SC-EXOs treated with PF could regulate the expression of proteins downstream of IRE1α pathway in ER stress (P < 0.05 or P < 0.01), improve the morphological integrity of ER, and reduce apoptosis in DRGn (P < 0.05 or P < 0.01).

Conclusion

PF regulates the information of ER stress carried by SC-EXOs and further affects downstream of IRE1α pathway in DRGn, thus reducing ER stress-induced apoptosis. PF can interfere with DPN through affecting information communication carried by EXOs between SCs and DRGn.

Serum albumin was negatively associated with diabetic peripheral neuropathy in Chinese population: a cross-sectional study

BACKGROUND

Previous studies that explored the relationship of serum albumin with diabetic peripheral neuropathy (DPN) have indicated inconsistent results. Thus, the present study aimed to evaluated the association between serum albumin and DPN, defined as vibration perception threshold (VPT) values ≥ 25 V and/or inability to feel the monofilament, in Chinese patients with type 2 diabetes mellitus (T2DM).

METHODS

1465 T2DM patients aged ≥ 16 years, who completed the measurement of serum albumin and DPN screening between 2012 and 2015, were included in the cross-sectional study. Correlation and multivariate logistic regression analysis models were used to evaluate the possible relationship between serum albumin and DPN.

RESULTS

Patients with higher quartiles of serum albumin had significantly lower VPT values and prevalence of DPN compared with those with lower quartiles (P for trend < 0.01), and there was an inverse relationship between serum albumin and VPT values and prevalence of DPN (all P < 0.01). Multivariate logistic regression analysis demonstrated that the risk of DPN was progressively decreased across serum albumin quartiles (P for trend < 0.01), and participants in the highest quartile of serum albumin were at a significantly decreased risk of DPN compared to those in the lowest quartile (odds rate: 0.311, 95% confidence intervals 0.134-0.724, P < 0.01). ROC analysis revealed that the optimal cutoff point of serum albumin for the prevalence of DPN was 39.95 g/L in patients with T2DM, with a sensitivity of 65.88% and a specificity of 66.7%.

CONCLUSIONS

Decreased levels of serum albumin might be correlated with increased risk of DPN in Chinese patients with T2DM. Future longitudinal studies with large samples are warranted to confirm our findings, and elucidate putative mechanisms for the association.

Adiposity Measurements and Metabolic Syndrome Are Linked Through Circulating Neuregulin 4 and Adipsin Levels in Obese Adults

Background

Adiposity and adipokines are associated with metabolic disorders, but little is known regarding that whether adiposity measurements link metabolic syndrome (MetS) through circulating neuregulin 4 (Nrg4) and adipsin levels.

Materials and Methods

A total of 1212 subjects with a waist circumference greater than 90 cm for men or 80 cm for women were enrolled from a Chinese community. Circulating Nrg4 and adipsin levels were measured using commercial kits. Mediation analyses of circulating Nrg4 and adipsin were performed in the study using linear and logistic regression.

Results

Subjects with MetS had higher waist circumference, visceral fat level, and circulating adipsin level, and lower levels of circulating Nrg4 and muscle mass to visceral fat (MVF) ratio (all P < 0.05). In multivariable logistic regression analyses, after adjusting for confounding variables, per standard deviation (SD) increase in waist circumference and visceral fat level were significantly associated with increased odds of MetS [OR (95% CI), 1.42 (1.22–1.64); 2.20 (1.62–2.99); respectively]; and per SD reduction in MVF ratio was significantly associated with reduced odds of MetS [OR (95% CI), 0.65 (0.55–0.77)]. In the mediation analyses, both circulating Nrg4 and adipsin levels mediated the association between waist circumference (8.31% and 18.35%, respectively), visceral fat level (7.50% and 9.98%, respectively), and MVF ratio (5.80% and 9.86%, respectively) and MetS after adjustments.

Conclusion

These findings indicate that adiposity measurements and MetS are linked through circulating Nrg4 and adipsin levels in obese adults, suggesting that circulating Nrg4 and adipsin levels might be potential predictors for management of MetS.

Neuregulins: protective and reparative growth factors in multiple forms of cardiovascular disease

Neuregulins (NRGs) are protein ligands that act through ErbB receptor tyrosine kinases to regulate tissue morphogenesis, plasticity, and adaptive responses to physiologic needs in multiple tissues, including the heart and circulatory system. The role of NRG/ErbB signaling in cardiovascular biology, and how it responds to physiologic and pathologic stresses is a rapidly evolving field. While initial concepts focused on the role that NRG may play in regulating cardiac myocyte responses, including cell survival, growth, adaptation to stress, and proliferation, emerging data support a broader role for NRGs in the regulation of metabolism, inflammation, and fibrosis in response to injury. The constellation of effects modulated by NRGs may account for the findings that two distinct forms of recombinant NRG-1 have beneficial effects on cardiac function in humans with systolic heart failure. NRG-4 has recently emerged as an adipokine with similar potential to regulate cardiovascular responses to inflammation and injury. Beyond systolic heart failure, NRGs appear to have beneficial effects in diastolic heart failure, prevention of atherosclerosis, preventing adverse effects on diabetes on the heart and vasculature, including atherosclerosis, as well as the cardiac dysfunction associated with sepsis. Collectively, this literature supports the further examination of how this developmentally critical signaling system functions and how it might be leveraged to treat cardiovascular disease.

Alteration of serum neuregulin 4 and neuregulin 1 in gestational diabetes mellitus

CONTEXT

Neuregulin 4 (Nrg4) and neuregulin 1 (Nrg1) have been shown to play vital roles in several disorders of glucose metabolism. The pathophysiological role of Nrg4 and Nrg1 in gestational diabetes mellitus (GDM), however, remains poorly understood. We assessed the clinical relevance of the two cytokines in patients with GDM.

METHODS

The study recruited 36 GDM patients and 38 age-matched, gestational age (24-28 weeks of gestation)-matched, and BMI (during pregnancy)-matched controls in this study. Serum Nrg4 and Nrg1 were measured using ELISA. Inflammatory factors such as IL-6, IL-1β, leptin, TNF-α, and monocyte chemotactic protein 1 (MCP-1) were determined via Luminex technique.

RESULTS

Serum Nrg4 in GDM patients was significantly lower than that in the controls, while Nrg1 was significantly higher in the GDM group (p < 0.01). Inflammatory factors such as IL-6, leptin, and TNF-α were significantly increased in GDM patients, while MCP-1 and IL-1β were not significantly different between the two groups. In addition, serum Nrg4 was negatively correlated with fasting glucose (r = -0.438, p = 0.008), HOMA-IR (r = -0.364, p = 0.029), IL-6 (r = -0.384, p = 0.021), leptin (r = -0.393, p = 0.018), TNF-α (r = -0.346, p = 0.039), and MCP-1 (r = -0.342, p = 0.041), and positively correlated with high-density lipoprotein cholesterol (HDL-C) (r = -0.357, p = 0.033) in GDM group. Serum Nrg1 was positively correlated with BMI (r = 0.452, p = 0.006), fasting glucose (r = 0.424, p = 0.010), HOMA-IR (r = 0.369, p = 0.027), and triglyceride (r = 0.439, p = 0.007). The decrease of Nrg4 and the increase of Nrg1 were significantly related to the increased prevalence of GDM. Finally, ROC curve results indicated that Nrg1 combined with IL-6 and TNF-α might be an effective means for GDM screening.

CONCLUSIONS

Lower circulating Nrg4 and higher circulating Nrg1 serve risk factors of GDM. Nrg1 combined with IL-6 and TNF-α might be a potential tool for GDM screening.

Clinical importance of neuregulin-4 and its receptor ErbB4 in periodontal disease pathogenesis

OBJECTIVE

The aim of this clinical trial was to evaluate the levels of Neuregulin-4 (Nrg4), Erb-b2 receptor tyrosine kinase 4 (ErbB4), interleukin (IL)-6, IL-10, nitric oxide synthase (NOS)-2, and arginase (Arg)-1 in periodontal health and disease.

MATERIALS AND METHODS

This study includes systemically healthy 20 periodontally healthy (H), 20 gingivitis (G), 20 stage II periodontitis (P1), and 20 stage III periodontitis (P2) subjects. Periodontal clinical measurements and samples of gingival crevicular fluid (GCF) and serum were obtained at baseline and 4 weeks after non-surgical periodontal treatment (NSPT). Enzyme-linked immunosorbent assay (ELISA) was used to determine ErbB4, Nrg4, IL-6, IL-10, NOS2, and Arg1 levels in all samples.

RESULTS

GCF ErbB4 and Nrg4 total amounts and IL-6/IL-10 ratio were significantly higher in G, P1, and P2 groups than H group. Serum NOS2 levels were significantly lower, whereas serum Arg1 levels were higher in H group than the others. The GCF levels of ErbB4 and Nrg4 were significantly decreased after NSPT in G, P1, and P2 groups. Additionally, the GCF levels of ErbB4 and Nrg4 were positively correlated with all clinical parameters and IL-6/IL-10 ratio.

CONCLUSIONS

Nrg4 and its receptor ErbB4 might have crucial roles in the pathogenesis of periodontal disease. These results should be verified with future prospective studies to further clarify the exact role of those biomarkers.

Clinical significance of serum concentrations of neuregulin-4, in acute coronary syndrome

Acute coronary syndrome (ACS) is closely associated with an increased risk of death. Nrg4, a novel adipocytokine, has negative correlations with indicators of metabolic syndrome. Here, we investigated whether circulating Nrg4 associates with the prevalence of ACS. In this case-control study, a total of 257 subjects (144 patients with ACS and 56 patients diagnosed with stable angina pectoris (SAP)) compared to 57 healthy controls. Serum Nrg4 and hs-CRP concentrations were determined by ELISA. The associations of circulating Nrg4 with other clinical parameters were also analyzed. Serum levels of Nrg4 were lower in patients compared to the control subjects (0.7 ± 0.53 ng/mL versus 1.1 ± 0.9 ng/mL, P = 0.018). There was a significant association between higher Nrg4 level and lower risk of ACS (OR = 0.15; 95%CI = 0.02–0.9; P = 0.046), but not with SAP. This association was independent of potential confounders including traditional cardiovascular risk factors. The distribution of patients with no, 1, 2 and 3 vessel stenosis was significantly different in Nrg4 quartiles. Patients in the lower quartile of Nrg4 were more likely to experience 3 vessel diseases. Serum levels of Nrg4 correlated negatively with HDL-cholesterol in ACS patients. Decreased serum levels of Nrg4 might be an independent risk factor for ACS.

The Pharmacological Mechanism of Diabetes Mellitus-Associated Overactive Bladder and Its Treatment with Botulinum Toxin A

Diabetes mellitus (DM) is an independent risk factor for overactive bladder (OAB). The pathophysiology of DM-associated OAB is multifactorial and time-dependent. Diabetic bladder dysfunction is highly associated with diabetic complications, mainly including diabetic neuropathy and atherosclerosis. Chronic systemic inflammation and bladder urothelial inflammation may contribute to the onset of OAB. Intravesical botulinum toxin A (BoNT-A) injection has proved to be a successful treatment for idiopathic and neurogenic OAB. BoNT-A can inhibit the efferent pathways of the bladder as well as the chronic inflammation and hypersensitivity via the afferent pathways. We conducted a review of the published literature in Pubmed using a combination of two keywords, namely “botulinum toxin A” (BoNT-A) and “overactive bladder”, with or without the additional keywords “detrusor overactivity”, “diabetes mellitus”, “inflammation”, and “urodynamic study”. We also reviewed the experience of our research teams, who have published several studies of the association between DM and OAB. Since limited data support the effectiveness and safety of BoNT-A for treating patients with DM-associated OAB, a comprehensive evaluation of diabetic complications and urodynamic study is needed before treatment. In the future, it is imperative to explore the clinical characteristics and inflammatory biomarkers of diabetes as determining predictors of the treatment efficacy.

A systematic review of the association of neuregulin 4, a brown fat-enriched secreted factor, with obesity and related metabolic disturbances

Neuregulin 4 (Nrg4), a novel brown fat-enriched hormone, plays a key role in the modulation of glucose and lipid metabolism and energy balance. Recent data have demonstrated that the expression of Nrg4 is substantially down-regulated in mouse and human obesity, making its regulatory aspect intriguing. Because of the close relationship between Nrg4, obesity, and associated metabolic diseases, this systematic review aimed to assess the association of Nrg4 with obesity and related metabolic disturbances, emphasizing its possible mechanisms of action in these disorders. We searched PubMed/Medline, ScienceDirect, Scopus, EMBASE, ProQuest, and Google Scholar up until June 2019. The evidence reviewed here indicates that Nrg4 may contribute to the prevention of obesity and related metabolic complications by elevating brown adipose tissue activity, increasing the expression of thermogenic markers, decreasing the expression of lipogenic/adipogenic genes, exacerbating white adipose tissue browning, increasing the number of brite/beige adipocytes, promoting hepatic fat oxidation and ketogenesis, inducing neurite outgrowth, enhancing blood vessels in adipose tissue, increasing the circulatory levels of healthy adipokines, and improving glucose homeostasis. Thus, Nrg4 appears to be a novel therapeutic strategy for the treatment of obesity and associated metabolic complications. However, prospective cohort studies are warranted to confirm these outcomes.

Changes of circulating neuregulin 4 and its relationship with 25-hydroxy vitamin D and other diabetic vascular complications in patients with diabetic peripheral neuropathy

BACKGROUND

Neuregulin 4 (Nrg4) is a novel neurotrophic adipokine associated with the development of diabetic peripheral neuropathy (DPN), however, the pathological mechanism remains poorly understood. The purpose of our study was to investigate the association of circulating Nrg4 with DPN and 25-hydroxy vitamin D [25(OH)D], a multifunctional secosteroid hormone that regulates other neurotrophic factors and adipokines gene expression, and other diabetic vascular complications.

METHODS

Circulating Nrg4 levels were measured with an ELISA kit in 164 newly diagnosed type 2 diabetes mellitus (nT2DM) patients. The relationship between circulating Nrg4 and DPN and other parameters was analyzed.

RESULTS

Circulating Nrg4 levels were significantly lower in nT2DM patients with DPN than those without, and subjects in the highest quartile of circulating Nrg4 had significantly lower vibration perception threshold (VPT), the prevalence of DPN, the proportion of persons with VPT > 25 V, and significantly higher circulating 25(OH)D (all P < 0.01). Moreover, circulating Nrg4 was positively and independently associated with 25(OH)D, and was negatively with VPT (P < 0.01 or P < 0.05), but showed no associations with the prevalence of peripheral arterial disease, diabetic nephropathy, and diabetic retinopathy (all P > 0.05). Additionally,the prevalence of DPN and risk of DPN development were progressively decreased with increasing circulating Nrg4 quartiles, independently of potential confounding factors.

CONCLUSIONS

These data demonstrate that decreased levels of circulating Nrg4 might lead to the development of DPN through its close interaction with circulating 25(OH)D not with other diabetic vascular complications. Further prospective studies are needed to identify our findings in these populations.

Physiological serum total bilirubin concentrations were inversely associated with diabetic peripheral neuropathy in Chinese patients with type 2 diabetes: a cross-sectional study

BACKGROUND

Although bilirubin has been generally regarded as a waste with potential neurotoxicity at high levels, a few clinical studies suggest a potential protective role of physiological serum total bilirubin (TBIL) concentrations in diabetic peripheral neuropathy (DPN). However, the pathological mechanisms underlying the relationship remain poorly understood. The objective of this study was to explore the relationship between serum TBIL and DPN, and clinical and laboratory parameters.

METHODS

Serum TBIL was measured in 1342 patients with type 2 diabetes mellitus (T2DM). The relationship between TBIL and DPN and other parameters was analyzed.

RESULTS

Serum TBIL levels were significantly lower in T2DM patients with DPN, and were independently and negatively associated with vibration perception thresholds (VPT) (P < 0.01 or P < 0.05). Moreover, serum TBIL was negatively associated with neutrophil and white blood cell counts, fibrinogen, and the prevalence of hypertension, diabetic foot ulceration, peripheral arterial disease, diabetic nephropathy and diabetic retinopathy (P < 0.01 or P < 0.05). Additionally, serum TBIL was an independent decisive factor for the presence of DPN after multivariate adjustment. Compared to the highest quartile of TBIL, the lower quartiles were associated with a significantly increased risk of DPN (P < 0.01). Last but most importantly, the analysis of receiver operating characteristic curves revealed that the best cutoff value for serum TBIL to predict DPN was 10.75 μmol/L (sensitivity 54.6% and specificity 62.9%).

CONCLUSIONS

These findings suggest that lower physiological serum TBIL may be associated with the presence of DPN due to its decreased anti-inflammatory and vascular protective effects.