New Insights into Adipokines as Potential Biomarkers for Type-2 Diabetes Mellitus

Comparison of the effects of empagliflozin and sitagliptin, as add-on to metformin, on serum levels of asprosin and metabolic parameters in patients with type 2 diabetes mellitus

The effect of sitagliptin and empagliflozin on serum levels of asprosin and metabolic parameters in patients with type 2 diabetes mellitus (T2DM) was assessed in a non-randomized, prospective observational study. Seventy-nine T2DM patients, without adequate glycemic control with metformin monotherapy, were included in the study. In addition to the ongoing metformin treatment, patients received sitagliptin 100 mg and empagliflozin 10 mg once daily for 12 weeks. Anthropometric parameters, lipid and glycemic profile, insulin resistance (homeostasis model assessment of insulin resistance index [HOMA-IR]), and asprosin serum levels were assessed at baseline and after 12 weeks of therapy. Both empagliflozin and sitagliptin treatments led to similar, significant improvement in fasting blood glucose (FBG) and hemoglobin A1C (HbA1C). Compared to baseline, triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C) were improved with both treatments, but empagliflozin led to the more improvement. No significant change of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) were observed in either group. Insulin resistance was significantly attenuated in both groups, but to a greater degree with empagliflozin treatment. The reduction in serum asprosin levels from baseline was significantly higher in patients taking empagliflozin compared to those receiving sitagliptin. Additionally, individuals on empagliflozin exhibited a more decrease in body mass index (BMI) and body weight compared to those on sitagliptin. According to our findings, the addition of empagliflozin to metformin appeared to offer greater benefits compared to the addition of sitagliptin in terms of decreasing asprosin levels and improving certain metabolic parameters in T2DM patients.

Resistin predicts disease severity and survival in patients with pulmonary arterial hypertension

BACKGROUND

Abnormal remodeling of distal pulmonary arteries in patients with pulmonary arterial hypertension (PAH) leads to progressively increased pulmonary vascular resistance, followed by right ventricular hypertrophy and failure. Despite considerable advancements in PAH treatment prognosis remains poor. We aim to evaluate the potential for using the cytokine resistin as a genetic and biological marker for disease severity and survival in a large cohort of patients with PAH.

METHODS

Biospecimens, clinical, and genetic data for 1121 adults with PAH, including 808 with idiopathic PAH (IPAH) and 313 with scleroderma-associated PAH (SSc-PAH), were obtained from a national repository. Serum resistin levels were measured by ELISA, and associations between resistin levels, clinical variables, and single nucleotide polymorphism genotypes were examined with multivariable regression models. Machine-learning (ML) algorithms were applied to develop and compare risk models for mortality prediction.

RESULTS

Resistin levels were significantly higher in all PAH samples and PAH subtype (IPAH and SSc-PAH) samples than in controls (P < .0001) and had significant discriminative abilities (AUCs of 0.84, 0.82, and 0.91, respectively; P < .001). High resistin levels (above 4.54 ng/mL) in PAH patients were associated with older age (P = .001), shorter 6-min walk distance (P = .001), and reduced cardiac performance (cardiac index, P = .016). Interestingly, mutant carriers of either rs3219175 or rs3745367 had higher resistin levels (adjusted P = .0001). High resistin levels in PAH patients were also associated with increased risk of death (hazard ratio: 2.6; 95% CI: 1.27-5.33; P < .0087). Comparisons of ML-derived survival models confirmed satisfactory prognostic value of the random forest model (AUC = 0.70, 95% CI: 0.62-0.79) for PAH.

CONCLUSIONS

This work establishes the importance of resistin in the pathobiology of human PAH. In line with its function in rodent models, serum resistin represents a novel biomarker for PAH prognostication and may indicate a new therapeutic avenue. ML-derived survival models highlighted the importance of including resistin levels to improve performance. Future studies are needed to develop multi-marker assays that improve noninvasive risk stratification.

In the Pursuit of Metabolic Markers of Systemic Sclerosis-Plasma Adiponectin and Omentin-1 in Monitoring the Course of the Disease

Systemic sclerosis (SSc) is a connective tissue disease leading to cutaneous and visceral fibrosis. Pathological features of SSc include immune dysregulation, vasculopathy, and impaired angiogenesis. Adipokines act as cytokines and hormones and are involved in various pathological processes, including metabolic disorders, inflammation, vasculopathy, and fibrosis. This study aimed to determine the level of omentin-1 and adiponectin to evaluate their potential role in the pathogenesis of SSc. We assessed serum omentin-1 and adiponectin as well as metabolic parameters in 58 patients with SSc and 30 healthy controls. The follow-up was performed in SSc individuals. Omentin-1 levels were significantly higher in SSc individuals as compared to the controls. In post-hoc analysis, omentin-1 was higher in the group with disease duration ≥7 years than in the control group. A positive correlation was noted between disease duration and both adipokines and increased with longer disease duration. However, there were no correlations between selected adipokines and metabolic parameters. Enhanced omentin-1 levels and higher levels of omentin-1 in patients with longer disease duration may suggest that omentin-1 is involved in the pathomechanisms of SSc as its concentrations are not directly related to BMI, age, and insulin resistance.

Role of Chemerin/ChemR23 axis as an emerging therapeutic perspective on obesity-related vascular dysfunction

Sufficient epidemiological investigations demonstrate that there is a close correlation between obesity and vascular dysfunction. Nevertheless, specific mechanisms underlying this link remain currently unclear. Given the crucial and decisive role of vascular dysfunction in multitudinous diseases, various hypotheses had been proposed and numerous experiments were being carried out. One recognized view is that increased adipokine secretion following the expanded mass of white adipose tissue due to obesity contributes to the regulation of vascular function. Chemerin, as a neo-adipokine, whose systemic level is elevated in obesity, is believed as a regulator of adipogenesis, inflammation, and vascular dysfunction via binding its cell surface receptor, chemR23. Hence, this review aims to focus on the up-to-date proof on chemerin/chemR23 axis-relevant signaling pathways, emphasize the multifarious impacts of chemerin/chemR23 axis on vascular function regulation, raise certain unsettled questions to inspire further investigations, and explore the therapeutic possibilities targeting chemerin/chemR23.

Review of Novel Potential Insulin Resistance Biomarkers in PCOS Patients—The Debate Is Still Open

Research on proteins and peptides that play roles in metabolic regulation, which may be considered potential insulin resistance markers in some medical conditions, such as diabetes mellitus, obesity and polycystic ovarian syndrome (PCOS), has recently gained in interest. PCOS is a common endocrine disorder associated with hyperandrogenemia and failure of ovulation, which is often accompanied by metabolic abnormalities, including obesity, dyslipidemia, hyperinsulinemia, and insulin resistance. In this review, we focus on less commonly known peptides/proteins and investigate their role as potential biomarkers for insulin resistance in females affected by PCOS. We summarize studies comparing the serum fasting concentration of particular agents in PCOS individuals and healthy controls. Based on our analysis, we propose that, in the majority of studies, the levels of nesfastin-1, myonectin, omentin, neudesin were decreased in PCOS patients, while the levels of the other considered agents (e.g., preptin, gremlin-1, neuregulin-4, xenopsin-related peptide, xenin-25, and galectin-3) were increased. However, there also exist studies presenting contrary results; in particular, most data existing for lipocalin-2 are inconsistent. Therefore, further research is required to confirm those hypotheses, as well as to elucidate the involvement of these factors in PCOS-related metabolic complications.

Precision medicine in secondary prevention of ischemic stroke: how may blood-based biomarkers help in clinical routine? An expert opinion

PURPOSE OF REVIEW

One in eight patients unfortunately suffers a new stroke within 5 years of their first stroke, even today. Research in precision medicine could lead to a more individualized treatment allocation, possibly achieving lower recurrence rates of ischemic stroke. In this narrative review, we aim to discuss potential clinical implementation of several promising candidate blood biomarkers.

RECENT FINDINGS

We discuss specifically some promising blood-based biomarkers, which may improve the identification of underlying causes as well as risk stratification of patients according to their specific cerebrovascular risk factor pattern.

SUMMARY

Multimodal profiling of ischemic stroke patients by means of blood biomarkers, in addition to established clinical and neuroradiological data, may allow in the future a refinement of decision algorithms for treatment allocation in secondary ischemic stroke prevention.

Heart Failure and Diabetes Mellitus: Biomarkers in Risk Stratification and Prognostication

Heart failure (HF) and type 2 diabetes mellitus (T2DM) have a synergistic effect on cardiovascular (CV) morbidity and mortality in patients with established CV disease (CVD). The aim of this review is to summarize the knowledge regarding the discriminative abilities of conventional and novel biomarkers in T2DM patients with established HF or at higher risk of developing HF. While conventional biomarkers, such as natriuretic peptides and high-sensitivity troponins demonstrate high predictive ability in HF with reduced ejection fraction (HFrEF), this is not the case for HF with preserved ejection fraction (HFpEF). HFpEF is a heterogeneous disease with a high variability of CVD and conventional risk factors including T2DM, hypertension, renal disease, older age, and female sex; therefore, the extrapolation of predictive abilities of traditional biomarkers on this population is constrained. New biomarker-based approaches are disputed to be sufficient for improving risk stratification and the prediction of poor clinical outcomes in patients with HFpEF. Novel biomarkers of biomechanical stress, fibrosis, inflammation, oxidative stress, and collagen turn-over have shown potential benefits in determining prognosis in T2DM patients with HF regardless of natriuretic peptides, but their role in point-to-care and in routine practice requires elucidation in large clinical trials.

Association of serum CTRP9 levels with cardiac autonomic neuropathy in patients with type 2 diabetes mellitus

AIMS

Cardiac autonomic neuropathy (CAN) is a serious complication of diabetes and is associated with adipokines. The C1q tumor necrosis factor-related protein 9 (CTRP9) is a newly discovered adipokine. This study aimed to evaluate the association of serum CTRP9 levels with the prevalence and severity of CAN in patients with type 2 diabetes mellitus.

MATERIALS AND METHODS

We enrolled 262 patients (aged ≥18 years) with type 2 diabetes mellitus into this study. Standard cardiovascular autonomic reflex tests (CARTs) were used to assess CAN and patients were divided into three groups accordingly: a non-CAN group, an early CAN group, and a definite CAN group. Serum CTRP9 levels were measured by enzyme-linked immunosorbent assay, and the tertiles were calculated.

RESULTS

Serum CTRP9 levels decreased significantly in the early CAN and definite CAN groups (P < 0.05). The percentage of definite CAN was the highest at the minimum tertile of serum CTRP9 level (T1; P < 0.05). Additionally, serum CTRP9 levels were negatively correlated with age, DM duration, hemoglobin A1c (HbA1c), and fasting plasma glucose (FPG) while positively correlated with high-density lipoprotein cholesterol (HDL; P < 0.05). The level of CTRP9 was also significantly associated with the four indexes of CARTs (P < 0.05). Furthermore, CTRP9 was a protective factor for definite CAN (P < 0.05). Compared with the maximum tertile (T3) of the serum CTRP9 levels, a decreased level of serum CTRP9 in T1 significantly increased the prevalence ratio of definite CAN in patients with type 2 diabetes mellitus (P < 0.05).

CONCLUSION

Serum CTRP9 levels were independently associated with definite CAN. CTRP9 represents a reliable biomarker for exploring CAN in patients with type 2 diabetes mellitus.

Anthocyanins regulate serum adipsin and visfatin in patients with prediabetes or newly diagnosed diabetes: a randomized controlled trial

BACKGROUND

Epidemiological studies have suggested that adipsin and visfatin are associated with the development of type 2 diabetes. This is the first study to investigate the effects of supplementation with purified anthocyanins on serum adipsin and visfatin in patients with prediabetes or newly diagnosed diabetes.

METHODS

A total of 160 participants with prediabetes or newly diagnosed diabetes (40-75 years old) were given 320 mg anthocyanins or placebo daily for 12 weeks in a randomized trial. Serum adipsin, serum visfatin, lipids and glycated hemoglobin A1c (HbA1c) were measured. The areas under the curve (AUCs) for glucose, insulin and C-peptide were determined before-and after-treatment by a standard 3-h 75 g oral glucose tolerance test (OGTT).

RESULTS

Relatively significant increases in serum adipsin (net change 0.15 µg/mL [0.03, 0.27], p = 0.018) and decreases in visfatin (-3.5 ng/mL [-6.69, -0.31], p = 0.032) were observed between the anthocyanins and placebo groups. We also observed significant improvements in HbA1c (-0.11% [-0.22, -0.11], p = 0.033), apolipoprotein A-1 (apo A-1) (0.12 g/L [0.03, 0.21], p = 0.012) and apolipoprotein B (apo B) (-0.07 g/L [-0.14, -0.01], p = 0.033) in response to the anthocyanins intervention.

CONCLUSION

Purified anthocyanins supplementation for 12 weeks increased serum adipsin and decreased serum visfatin in patients with prediabetes or newly diagnosed diabetes. Trial registration ClinicalTrials.gov, identifier: NCT02689765.

Sarcopenic obesity: Myokines as potential diagnostic biomarkers and therapeutic targets?

Sarcopenic obesity (SO) is a condition characterized by the occurrence of both sarcopenia and obesity and imposes a heavy burden on the health of the elderly. Controversies and challenges regarding the definition, diagnosis and treatment of SO still remain because of its complex pathogenesis and limitations. Over the past few decades, numerous studies have revealed that myokines secreted from skeletal muscle play significant roles in the regulation of muscle mass and function as well as metabolic homeostasis. Abnormalities in myokines may trigger and promote the pathogenesis underlying age-related and metabolic diseases, including obesity, sarcopenia, type 2 diabetes (T2D), and SO. This review mainly focuses on the role of myokines as potential biomarkers for the early diagnosis and therapeutic targets in SO.

Molecular biomarkers in diabetes mellitus (DM)

Background: Diabetes mellitus (DM) is a growing epidemic metabolic syndrome, which affects near 5.6% of the world's population. Almost 12% of health expenditure is dedicated to this disorder. Discovering and developing biomarkers as a practical guideline with high specificity and sensitivity for the diagnosis, prognosis, and clinical management of DM is one of the subjects of great interest among DM researchers due to the long-lasting asymptomatic clinical manifestation of DM. In this study, we described a recently identified molecular biomarker involved in DM. Methods: This review study was done at the Diabetes Research Center affiliated to Shahid Sadoughi University of Medical Sciences. PubMed, Scopus, Google Scholar, and Web of Science were searched using the following keywords: "diabetes mellitus", "biomarker", "microRNA", "diagnostic tool" and "clinical manifestation." Results: A total of 107 studies were finally included in this review. After evaluating numerous articles, including original, metaanalysis, and review studies, we focused on molecular biomarkers involved in DM diagnosis and management. Conclusion: Increasing interest in biomarkers associated with DM goes back to its role in decreasing diabetes-related morbidity and mortality. This review focused on major molecular biomarkers such as proteomic and microRNA (miRNAs) as novel and interesting DM biomarkers that can help achieve timely diagnosis of DM.

Relationships among resistin, adiponectin, and leptin and microvascular complications in patients with type 2 diabetes mellitus

Objective

To investigate the relationships among serum resistin, adiponectin, and leptin and microvascular complications in patients with type 2 diabetes mellitus (T2DM).

Methods

A total of 120 patients with T2DM were divided into non-microangiopathy and microangiopathy groups. Sixty age- and sex-matched healthy subjects were used as a normal control (NC) group. Body height, body mass, waist circumference, and blood pressure were determined, and waist/hip ratio (WHR), body mass index, blood glucose, lipids, resistin, leptin, adiponectin, free fatty acids (FFA), high-sensitivity C-reactive protein (hs-CRP), fasting insulin, hemoglobin A1c, and homeostatic model assessment of insulin resistance (HOMA-IR) were compared among the three groups.

Results

Serum levels of resistin, leptin, FFA, and hs-CRP were significantly higher and levels of adiponectin were significantly lower in patients in the non-microangiopathy (n = 60) and microangiopathy groups (n = 60) compared with the NC group (n = 60). Serum resistin and leptin levels in patients with T2DM were positively correlated with WHR, hs-CRP, FFA, HOMA-IR, and triglycerides, but negatively correlated with high-density lipoprotein-cholesterol (HDL-C). Serum adiponectin levels in patients with T2DM were negatively correlated with WHR, hs-CRP, FFA, HOMA-IR, and triglycerides, but positively correlated with HDL-C.

Conclusion

Serum resistin, adiponectin, and leptin levels correlate with the occurrence of T2DM and microvascular complications.

Insulin and Insulin Receptors in Adipose Tissue Development

Insulin is a major endocrine hormone also involved in the regulation of energy and lipid metabolism via the activation of an intracellular signaling cascade involving the insulin receptor (INSR), insulin receptor substrate (IRS) proteins, phosphoinositol 3-kinase (PI3K) and protein kinase B (AKT). Specifically, insulin regulates several aspects of the development and function of adipose tissue and stimulates the differentiation program of adipose cells. Insulin can activate its responses in adipose tissue through two INSR splicing variants: INSR-A, which is predominantly expressed in mesenchymal and less-differentiated cells and mainly linked to cell proliferation, and INSR-B, which is more expressed in terminally differentiated cells and coupled to metabolic effects. Recent findings have revealed that different distributions of INSR and an altered INSR-A:INSR-B ratio may contribute to metabolic abnormalities during the onset of insulin resistance and the progression to type 2 diabetes. In this review, we discuss the role of insulin and the INSR in the development and endocrine activity of adipose tissue and the pharmacological implications for the management of obesity and type 2 diabetes.

The Proposal of Molecular Mechanisms of Weak Organic Acids Intake-Induced Improvement of Insulin Resistance in Diabetes Mellitus via Elevation of Interstitial Fluid pH

Blood contains powerful pH-buffering molecules such as hemoglobin (Hb) and albumin, while interstitial fluids have little pH-buffering molecules. Thus, even under metabolic disorder conditions except severe cases, arterial blood pH is kept constant within the normal range (7.35~7.45), but the interstitial fluid pH under metabolic disorder conditions becomes lower than the normal level. Insulin resistance is one of the most important key factors in pathogenesis of diabetes mellitus, nevertheless the molecular mechanism of insulin resistance occurrence is still unclear. Our studies indicate that lowered interstitial fluid pH occurs in diabetes mellitus, causing insulin resistance via reduction of the binding affinity of insulin to its receptor. Therefore, the key point for improvement of insulin resistance occurring in diabetes mellitus is development of methods or techniques elevating the lowered interstitial fluid pH. Intake of weak organic acids is found to improve the insulin resistance by elevating the lowered interstitial fluid pH in diabetes mellitus. One of the molecular mechanisms of the pH elevation is that: (1) the carboxyl group (R-COO⁻) but not H⁺ composing weak organic acids in foods is absorbed into the body, and (2) the absorbed the carboxyl group (R-COO⁻) behaves as a pH buffer material, elevating the interstitial fluid pH. On the other hand, high salt intake has been suggested to cause diabetes mellitus; however, the molecular mechanism is unclear. A possible mechanism of high salt intake-caused diabetes mellitus is proposed from a viewpoint of regulation of the interstitial fluid pH: high salt intake lowers the interstitial fluid pH via high production of H⁺ associated with ATP synthesis required for the Na⁺,K⁺-ATPase to extrude the high leveled intracellular Na⁺ caused by high salt intake. This review article introduces the molecular mechanism causing the lowered interstitial fluid pH and insulin resistance in diabetes mellitus, the improvement of insulin resistance via intake of weak organic acid-containing foods, and a proposal mechanism of high salt intake-caused diabetes mellitus.