Serum and adipose tissue chemerin is differentially related to insulin sensitivity

Chemerin affects blood lipid profile of high-fat diet male mice in sedentary and exercise states via glucose and lipid metabolism enzymes

Adipokine chemerin plays important roles in disorders of glucose and lipid metabolism of obesity and obesity-related diseases, and exercise-induced improvement of glucose and lipid metabolism is closely related to the decrease of chemerin, but the mechanisms by which chemerin regulates glucose and lipid metabolism remain unclarified. Hypotestosterone induces male obesity and disorders of glucose and lipid metabolism through androgen receptor (AR) and its target genes: glucose and lipid metabolism-related molecules (including FOXO1, PEPCK, PGC-1α, and SCD1). Recently, the link between them has been reported that chemerin modulated the secretion of androgen. In this study, global chemerin knockout (chemerin (-/-)) mice were established to demonstrate the roles of chemerin in regulating blood glucose and blood lipid of mice under diet (high-fat (HFD) and normal diet) and exercise interventions and then to explore its mechanisms (AR - glucose and lipid metabolism enzymes). We found that the blood lipid and adipocyte size were low accompanied by the improvements in the levels of serum testosterone, gastrocnemius AR, and gastrocnemius FOXO1, SCD1, and PGC-1α in HFD chemerin (-/-) mice, but exercise-induced improvements of these indicators in HFD WT mice were attenuated or abolished in HFD chemerin (-/-) mice. In conclusion, the decrease of chemerin improved the blood lipid profile of HFD male mice at sedentary and exercise states, mediated partly by the increases of testosterone and AR to regulate glucose and lipid metabolism enzymes. To our knowledge, it is the first report that chemerin's regulation of glucose and lipid metabolism might be mediated by testosterone and AR in vivo.

Targeted Proteomics Reveals Functional Targets for Early Diabetes Susceptibility in Young Adults

BACKGROUND

The circulating proteome may encode early pathways of diabetes susceptibility in young adults for surveillance and intervention. Here, we define proteomic correlates of tissue phenotypes and diabetes in young adults.

METHODS

We used penalized models and principal components analysis to generate parsimonious proteomic signatures of diabetes susceptibility based on phenotypes and on diabetes diagnosis across 184 proteins in >2000 young adults in the CARDIA (Coronary Artery Risk Development in Young Adults study; mean age, 32 years; 44% women; 43% Black; mean body mass index, 25.6±4.9 kg/m2), with validation against diabetes in >1800 individuals in the FHS (Framingham Heart Study) and WHI (Women's Health Initiative).

RESULTS

In 184 proteins in >2000 young adults in CARDIA, we identified 2 proteotypes of diabetes susceptibility-a proinflammatory fat proteotype (visceral fat, liver fat, inflammatory biomarkers) and a muscularity proteotype (muscle mass), linked to diabetes in CARDIA and WHI/FHS. These proteotypes specified broad mechanisms of early diabetes pathogenesis, including transorgan communication, hepatic and skeletal muscle stress responses, vascular inflammation and hemostasis, fibrosis, and renal injury. Using human adipose tissue single cell/nuclear RNA-seq, we demonstrate expression at transcriptional level for implicated proteins across adipocytes and nonadipocyte cell types (eg, fibroadipogenic precursors, immune and vascular cells). Using functional assays in human adipose tissue, we demonstrate the association of expression of genes encoding these implicated proteins with adipose tissue metabolism, inflammation, and insulin resistance.

CONCLUSIONS

A multifaceted discovery effort uniting proteomics, underlying clinical susceptibility phenotypes, and tissue expression patterns may uncover potentially novel functional biomarkers of early diabetes susceptibility in young adults for future mechanistic evaluation.

The role of the autonomic nervous system in polycystic ovary syndrome

This article reviewed the relationship between the autonomic nervous system and the development of polycystic ovary syndrome (PCOS). PCOS is the most common reproductive endocrine disorder among women of reproductive age. Its primary characteristics include persistent anovulation, hyperandrogenism, and polycystic ovarian morphology, often accompanied by disturbances in glucose and lipid metabolism. The body's functions are regulated by the autonomic nervous system, which consists mainly of the sympathetic and parasympathetic nervous systems. The autonomic nervous system helps maintain homeostasis in the body. Research indicates that ovarian function in mammals is under autonomic neural control. The ovaries receive central nervous system information through the ovarian plexus nerves and the superior ovarian nerves. Neurotransmitters mediate neural function, with acetylcholine and norepinephrine being the predominant autonomic neurotransmitters. They influence the secretion of ovarian steroids and follicular development. In animal experiments, estrogen, androgens, and stress-induced rat models have been used to explore the relationship between PCOS and the autonomic nervous system. Results have shown that the activation of the autonomic nervous system contributes to the development of PCOS in rat. In clinical practice, assessments of autonomic nervous system function in PCOS patients have been gradually employed. These assessments include heart rate variability testing, measurement of muscle sympathetic nerve activity, skin sympathetic response testing, and post-exercise heart rate recovery evaluation. PCOS patients exhibit autonomic nervous system dysfunction, characterized by increased sympathetic nervous system activity and decreased vagal nerve activity. Abnormal metabolic indicators in PCOS women can also impact autonomic nervous system activity. Clinical studies have shown that various effective methods for managing PCOS regulate patients' autonomic nervous system activity during the treatment process. This suggests that improving autonomic nervous system activity may be an effective approach in treating PCOS.

Serum Chemerin Is Decreased by Roux-en-Y Gastric Bypass and Low Calorie-Formula Diet in Obese Individuals

The pleiotropic chemokine chemerin is involved in multiple processes in metabolism and inflammation. The present study aimed to elucidate its regulation in morbid obesity and during therapy-induced rapid weight loss. A total of 128 severely obese patients were enrolled, and their basal anthropometric and clinical parameters were assessed. In total, 64 individuals attended a conservative 12-month weight loss program that included a low calorie-formula diet (LCD), and 64 patients underwent bariatric surgery (Roux-en-Y gastric bypass, RYGB). Blood serum was obtained at study baseline and at follow-up visits after 3, 6, and 12 months. Systemic chemerin concentrations, as well as metabolic and immunological parameters, were quantified. During the 12-month period studied, serum chemerin levels decreased significantly with weight loss after bariatric surgery, as well as with conservative low calorie therapy; however, the effects of RYGB were generally stronger. No substantial associations of systemic chemerin concentrations with therapy-induced improvement of type 2 diabetes and with indicators of liver function and fibrosis were observed. We conclude that systemic chemerin levels decrease in obese individuals during weight loss, regardless of the therapeutic strategy. A potential involvement in weight loss-associated improvement of metabolic disorders and liver fibrosis remains to be further investigated.

Research progress of intramuscular fat formation based on co-culture

Intramuscular fat (IMF) is closely related to the meat quality of livestock and poultry. As a new cell culture technique in vitro, cell co-culture has been gradually applied to the related research of IMF formation because it can simulate the changes of microenvironment in vivo during the process of IMF cell formation. In the co-culture model, in addition to studying the effects of skeletal muscle cells on the proliferation and differentiation of IMF, we can also consider the role of many secretion factors in the formation of IMF, thus making the cell research in vitro closer to the real level in vivo. This paper reviewed the generation and origin of IMF, summarized the existing co-culture methods and systems, and discussed the advantages and disadvantages of each method as well as the challenges faced in the establishment of the system, with emphasis on the current status of research on the formation of IMF for human and animal based on co-culture technology.

Adherence to Healthy and Sustainable Dietary Patterns and Long-Term Chronic Inflammation: Data from the EPIC-Potsdam Cohort

OBJECTIVES

We explored the prospective associations between adherence to a priori chosen dietary patterns, including EAT-Lancet (EAT-L) and Mediterranean (tMDS) diet with long-term inflammatory responses in a German population sample.

DESIGN AND SETTING

Prospective cohort study.

PARTICIPANTS

A subsample of 636 predominantly healthy participants from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam study who were on average 51-years old at baseline.

MEASUREMENTS

Data was collected repeatedly between 1994/1998 - 2013. At baseline (1994/1998) and 6.8-years later (2001/2005), EAT-L and tMDS scores were derived from available food frequency questionnaires. Stable high, stable low, increasing, and decreasing adherence to EAT-L and tMDS were defined as scoring above/below baseline median at baseline and 6.8-years later. Long-term chronic inflammation was assessed based on the average values of repeated measurements of two inflammatory biomarkers - chemerin and high-sensitivity C-reactive protein (hs-CRP) - in plasma samples collected between 2010/2012 and 2013. Multivariable linear regression analysis adjusted for socio-demographic and lifestyle factors at baseline and in 2010/2012 was used to assess the association between diet adherence and long-term hs-CRP and chemerin concentrations.

RESULTS

Stable high or increasing adherence to EAT-L diet compared to stable low adherence was associated with slight reduction of long-term chemerin concentrations on the long run (stable high: -4.4%; increasing: -4.0%), not reaching statistical significance. Increasing adherence to tMDS compared to stable low adherence was also associated with a minor reduction in chemerin concentrations (-3.6%). Decreasing adherence to tMDS compared stable high adherence was associated with 2.7% higher chemerin. The associations were even less pronounced when hs-CRP was used as an outcome.

CONCLUSIONS

Adherence to healthy and sustainable dietary patterns defined using existing definitions for EAT-L and tMDS were associated with minor and not statistically significant reduction in the concentrations of inflammatory biomarkers on the long run. More research is needed to explore whether following these diets may represent a suitable approach for targeted prevention in the general population.

Adipose tissue and ovarian aging: Potential mechanism and protective strategies

Ovarian aging occurs approximately 10 years prior to the natural age-associated functional decline of other organ systems. With the increase of life expectancy worldwide, ovarian aging has gradually become a key health problem among women. Therefore, understanding the causes and molecular mechanisms of ovarian aging is very essential for the inhibition of age-related diseases and the promotion of health and longevity in women. Recently, studies have revealed an association between adipose tissue (AT) and ovarian aging. Alterations in the function and quantity of AT have profound consequences on ovarian function because AT is central for follicular development, lipid metabolism, and hormonal regulation. Moreover, the interplay between AT and the ovary is bidirectional, with ovary-derived signals directly affecting AT biology. In this review, we summarize the current knowledge of the complex molecular mechanisms controlling the crosstalk between the AT and ovarian aging, and further discuss how therapeutic targeting of the AT can delay ovarian aging.

Use of Physical Activity and Exercise to Reduce Inflammation in Children and Adolescents with Obesity

Childhood obesity is a leading public health problem worldwide, as it is increasingly prevalent and therefore responsible for serious obesity-related comorbidities, not only in childhood but also in adulthood. In addition to cardio-metabolic obesity-related disorders, recent evidence suggests that excess adipose tissue in turn is associated with immune cell infiltration, increased adipokine release, and the development of low-grade systemic inflammation obesity. Exercise is considered a non-pharmacological intervention that can delay obesity-related comorbidities, improving cardiovascular fitness and modulating the inflammatory processes. It has been reported that the anti-inflammatory effect of regular exercise may be mediated by a reduction in visceral fat mass, with a subsequent decrease in the release of adipokines from adipose tissue (AT) and/or by the induction of an anti-inflammatory environment. In this narrative review, we discuss the role of AT as an endocrine organ associated with chronic inflammation and its role in obesity-related complications, focusing on the effect of exercise in reducing inflammation in children and adolescents with obesity. Regular physical exercise must be considered as a natural part of a healthy lifestyle, and promoting physical activity starting from childhood is useful to limit the negative effects of obesity on health. The crucial role of the immune system in the development of obesity-induced inflammatory processes and the efficacy of exercise as an anti-inflammatory, non-pharmacological intervention may provide possible targets for the development of new treatments and early preventive strategies.

Differential Association of Selected Adipocytokines, Adiponectin, Leptin, Resistin, Visfatin and Chemerin, with the Pathogenesis and Progression of Type 2 Diabetes Mellitus (T2DM) in the Asir Region of Saudi Arabia: A Case Control Study

Background: Sedentary lifestyles, urbanization and improvements in socio-economic status have had serious effects on the burden of diabetes across the world. Diabetes is one of the 10 leading causes of death globally, and individuals with diabetes have a 2–3-fold increased risk of all-cause mortality. Adipose tissue is increasingly understood as a highly active endocrine gland that secretes many biologically active substances, including adipocytokines. However, the exact and discrete pathophysiological links between obesity and T2DM are not yet fully elucidated. Methods: In the current study, we present the association of five diverse adipocytokines, adiponectin, leptin, resistin, visfatin and chemerin, with T2DM in 87 patients (46 males and 41 females) with type 2 diabetes mellitus and 85 healthy controls (44 males and 41 females) from the Asir region of Saudi Arabia. The patients were divided into four groups: normal BMI, overweight, obese and severely obese. The baseline biochemical characteristics, including HbA1c and anthropometric lipid indices, such as BMI and waist–hip ratio, were determined by standard procedures, whereas the selected adipokine levels were assayed by ELISA. Results: The results showed significantly decreased levels of adiponectin in the T2DM patients compared to the control group, and the decrease was more pronounced in obese and severely obese T2DM patients. Serum leptin levels were significantly higher in the females compared to the males in the controls as well as all the four groups of T2DM patients. In the male T2DM patients, a progressive increase was observed in the leptin levels as the BMI increased, although these only reached significantly altered levels in the obese and severely obese patients. The serum leptin levels were significantly higher in the severely obese female patients compared to the controls, patients with normal BMI, and overweight patients. The leptin/adiponectin ratio was significantly higher in the obese and severely obese patients compared to the controls, patients with normal BMI, and overweight patients in both genders. The serum resistin levels did not show any significant differences between the males and females in thr controls or in the T2DM groups, irrespective of the BMI status of the T2DM patients. The visfatin levels did not reveal any significant gender-based differences, but significantly higher levels of visfatin were observed in the T2DM patients, irrespective of their level of obesity, although the higher values were observed in the obese and highly obese patients. Similarly, the serum chemerin levels in the controls, as well as in T2DM patients, did not show any significant gender-based differences. However, in the T2DM patients, the chemerin levels showed a progressive increase, with the increase in BMI reaching highly significant levels in the obese and severely obese patients, respectively. Conclusion: In summary, it is concluded that significantly altered concentrations of four adipokines, adiponectin, leptin, visfatin and chemerin, were found in the T2DM patient group compared to the controls, with more pronounced alterations observed in the obese and highly obese patients. Thus, it can be surmised that these four adipokines play a profound role in the onset, progression and associated complications of T2DM. In view of the relatively small sample size in our study, future prospective studies are needed on a large sample size to explore the in-depth relationship between adipokines and T2DM.

Salt-Sensitivity of Blood Pressure and Insulin Resistance

Salt sensitivity of blood pressure (SSBP) is an independent risk factor for cardiovascular morbidity and mortality that is seen in both hypertensive and normotensive populations. Insulin resistance (IR) strongly correlates with SSBP and affects nearly 50% of salt sensitive people. While the precise mechanism by which IR and SSBP relate remains elusive, several common pathways are involved in the genesis of both processes, including vascular dysfunction and immune activation. Vascular dysfunction associated with insulin resistance is characterized by loss of nitric oxide (NO)-mediated vasodilation and heightened endothelin-1 induced vasoconstriction, as well as capillary rarefaction. It manifests with increased blood pressure (BP) in salt sensitive murine models. Another common denominator in the pathogenesis of insulin resistance, hypertension, and salt sensitivity (SS) is immune activation involving pro-inflammatory cytokines like tumor necrosis factor (TNF)-α, IL-1β, and IL-6. In the last decade, a new understanding of interstitial sodium storage in tissues such as skin and muscle has revolutionized traditional concepts of body sodium handling and pathogenesis of SS. We have shown that interstitial Na⁺ can trigger a T cell mediated inflammatory response through formation of isolevuglandin protein adducts in antigen presenting cells (APCs), and that this response is implicated in salt sensitive hypertension. The peroxisome proliferator-activated receptor γ (PPARγ) is a transcription factor that modulates both insulin sensitivity and BP. PPARγ agonists increase insulin sensitivity and ameliorate salt sensitivity, whereas deficiency of PPARγ results in severe insulin resistance and hypertension. These findings suggest that PPARγ plays a role in the common pathogenesis of insulin sensitivity and salt sensitivity, perhaps via effects on the immune system and vascular function. The goal of this review is to discuss those mechanisms that may play a role in both SSBP and in insulin resistance.

The effects of alprostadil combined with α-lipoic acid in the treatment of senile diabetic nephropathy

OBJECTIVE

This study aimed to investigate the clinical efficacy of alprostadil combined with α-Lipoic acid (α-LA) in the treatment of senile diabetic nephropathy (SDN) and the combination's effect on the serum chemerin and neutrophil gelatinase-associated lipocalin (NGAL) expressions.

METHODS

Seventy-six patients with diabetic nephropathy (DN) admitted to our hospital from March 2018 to October 2019 were recruited as the research cohort. Among them, 36 patients who were administered alprostadil monotherapy were placed in the control group (CG), and the remaining 40 patients administered α-LA in addition to the alprostadil were placed in the research group (RG). The treatment effectiveness rate, the incidence of adverse reactions, and the changes in the renal function indexes (BUN, SCr, UAER) and the blood glucose indexes (FPG, 2hPG) were compared between the two groups.

RESULTS

The total effective rate in the RG was significantly higher than the total effective rate in the CG (P < 0.05). The renal function and blood glucose indexes dropped significantly after the treatment (P < 0.001). The chemerin and NGAL levels were significantly reduced in both groups after the treatment (P < 0.05), and the chemerin and NGAL expressions in the RG were significantly lower than they were in the CG (P < 0.05).

CONCLUSION

Alprostadil combined with α-LA is better than alprostadil monotherapy in the treatment of DN because it can improve the effectiveness rate, reduce the blood glucose, and improve the renal function while effectively reducing patients' serum chemerin and NGAL levels.

Aerobic interval training improves irisin and chemerin levels of both liver and visceral adipose tissues and circulating asprosin in rats with metabolic syndrome

The perturbation of adipokinetic hormones, such as irisin, chemerin, and asprosin has been reported to participate in pathological conditions (e.g., insulin resistance) and chronic inflammation. However, exercise training has been long established as an effective intervention for prevention and treatment of these chronic and metabolic diseases. This study was to examine the effects of aerobic continuous training (ACT) and aerobic interval training (AIT) on irisin and chemerin levels of liver tissue (LT) and visceral adipose tissue (VAT), circulating asprosin, and their relationships with cardiometabolic risk factors in rats with metabolic syndrome (MetS). Thirty-two male Wistar rats were randomly divided into four equal groups: normal control (N-Ctr), control (Ctr-MetS), ACT, and AIT. After familiarization, rats with exercise intervention performed either ACT or AIT five times a week over eight weeks. The level of irisin in both ACT and AIT groups was higher than the Ctr-MetS group in LT and VAT, with a greater improvement of LT level observed in AIT vs. ACT groups. Furthermore, the level of chemerin in LT and VAT was lower in both ACT and AIT groups than the Ctr-MetS group, whereas only AIT group exhibited a reduction of serum asprosin when compared to ACT and Ctr-MetS, along with the improvements of cardiometabolic markers, such as HOMA-IR and lipid profile. These findings may support the efficiency and effectiveness of AIT intervention in the modulation of these novel metabolic hormones and cardiometabolic risk factors for reduced risk of metabolic syndrome.

Diabetes and Obesity-Cumulative or Complementary Effects On Adipokines, Inflammation, and Insulin Resistance

Background: Diabetes and obesity are increasingly significant public health issues. The aim of this study was to evaluate the relationship between adipocytokines (leptin, ghrelin, and chemerin), inflammation (sVCAM1—soluble vascular adhesion molecule 1, sICAM1—soluble intercellular adhesion molecule 1), and insulin resistance in the presence of obesity and diabetes mellitus. Methods: 88 subjects, with a mean age of 61.96 ± 10.15 years, 75% of whom were women, were evaluated (in order to consider different associations between obesity and diabetes, subjects were categorized into four groups). Results: Overall, we found significant correlations between sICAM1-sVCAM1 rho = 0.426 and ghrelin-chemerin rho = −0.224. In the obesity + diabetes group, leptin correlated with sICAM1 rho = 0.786, and sVCAM1 negatively with glycemia/insulin rho = −0.85. Significant differences were found between the groups regarding sVCAM1 (p = 0.0134), leptin (p = 0.0265) and all insulin resistance scores, with differences influenced by the subjects’ gender. In conclusion, although there are currently many unknown aspects of the release and the role of various adipokines, in particular chemerin, its implication in early glucose metabolism dysregulation disorders seems very likely.

Characterization and Treatment of Inflammation and Insulin Resistance in Obese Adipose Tissue

Adipose tissue is the largest energy storage and protection organ. It is distributed subcutaneously and around the internal organs. It regulates metabolism by storing and releasing fatty acids and secreting adipokines. Excessive nutritional intake results in adipocyte hypertrophy and proliferation, leading to local hypoxia in adipose tissue and changes in the release of adipokines. These lead to recruit of more immune cells into adipose tissue and release of inflammatory signaling factors. Excess free fatty acids and inflammatory factors interfere with intracellular insulin signaling. In this review, we summarize the characteristics of obese adipose tissue and analyze how its inflammation causes insulin resistance. We further discuss the latest clinical research progress on the control of insulin resistance and inflammation resulting from obesity through anti-inflammatory therapy and bariatric surgery. Our review shows that targeted anti-inflammatory therapy is of great significance for obese patients with insulin resistance.