The Role of Apelin/Apelin Receptor in Energy Metabolism and Water Homeostasis: A Comprehensive Narrative Review

The intricate role of adipokines in cancer-related signaling and the tumor microenvironment: Insights for future research

Obesity represents a global health challenge, with adipose tissue acting as a highly active endocrine organ that synthesizes and secretes a diverse array of bioactive proteins, known as adipokines. These cell signaling molecules regulate metabolic equilibrium, inflammatory cascades, and immune surveillance, exerting substantial systemic effects. A growing body of evidence has also highlighted their key role in cancer biology, through their intricate impact on oncogenic signaling networks and the tumor microenvironment (TME). The TME, a highly dynamic and heterotypic network composed of malignant cells, infiltrating immune cells, stromal constituents, and extracellular matrix elements, facilitates tumor evolution and immune evasion. Among adipokines, adiponectin and leptin have been extensively studied. Research has shown that adiponectin exhibits tumor-suppressive properties, whereas leptin enhances proliferative, angiogenic, and inflammatory pathways that promote malignancy. However, these effects are context-dependent and, at times, contradictory across different studies. Furthermore, the functional landscape of adipokines in cancer extends beyond these paradigms, with emerging research identifying a broader spectrum of novel adipokines involved in cancer reprogramming. This review delineates the molecular interplay between adipokines and oncogenic pathways, elucidating their mechanistic contributions to TME crosstalk and immune modulation. Additionally, we examine their potential as diagnostic and prognostic biomarkers and assess their viability as therapeutic targets for precision oncology. By integrating current evidence and identifying unresolved questions, this review aims to refine our understanding of adipokine-driven tumor biology and establish a platform for future research.

Morphometric and Molecular Interplay in Hypertension-Induced Cardiac Remodeling with an Emphasis on the Potential Therapeutic Implications

Hypertension-induced cardiac remodeling is a complex process driven by interconnected molecular and cellular mechanisms that culminate in hypertensive myocardium, characterized by ventricular hypertrophy, fibrosis, impaired angiogenesis, and myocardial dysfunction. This review discusses the histomorphometric changes in capillary density, fibrosis, and mast cells in the hypertensive myocardium and delves into the roles of key regulatory systems, including the apelinergic system, vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) pathways, and nitric oxide (NO)/nitric oxide synthase (NOS) signaling in the pathogenesis of hypertensive heart disease (HHD). Capillary rarefaction, a hallmark of HHD, contributes to myocardial ischemia and fibrosis, underscoring the importance of maintaining vascular integrity. Targeting capillary density (CD) through antihypertensive therapy or angiogenic interventions could significantly improve cardiac outcomes. Myocardial fibrosis, mediated by excessive collagen deposition and influenced by fibroblast growth factor-2 (FGF-2) and transforming growth factor-beta (TGF-β), plays a pivotal role in the structural remodeling of hypertensive myocardium. While renin-angiotensin-aldosterone system (RAAS) inhibitors show anti-fibrotic effects, more targeted therapies are needed to address fibrosis directly. Mast cells, though less studied in humans, emerge as critical regulators of cardiac remodeling through their release of pro-fibrotic mediators such as histamine, tryptase, and FGF-2. The apelinergic system emerges as a promising therapeutic target due to its vasodilatory, anti-fibrotic, and cardioprotective properties. The system counteracts the deleterious effects of the RAAS and has demonstrated efficacy in preclinical models of hypertension-induced cardiac damage. Despite its potential, human studies on apelin analogs remain limited, warranting further exploration to evaluate their clinical utility. VEGF signaling plays a dual role, facilitating angiogenesis and compensatory remodeling during the early stages of arterial hypertension (AH) but contributing to maladaptive changes when dysregulated. Modulating VEGF signaling through exercise or pharmacological interventions has shown promise in improving CD and mitigating hypertensive cardiac damage. However, VEGF inhibitors, commonly used in oncology, can exacerbate AH and endothelial dysfunction, highlighting the need for therapeutic caution. The NO/NOS pathway is essential for vascular homeostasis and the prevention of oxidative stress. Dysregulation of this pathway, particularly endothelial NOS (eNOS) uncoupling and inducible NOS (iNOS) overexpression, leads to endothelial dysfunction and nitrosative stress in hypertensive myocardium. Strategies to restore NO bioavailability, such as tetrahydrobiopterin (BH4) supplementation and antioxidants, hold potential for therapeutic application but require further validation. Future studies should adopt a multidisciplinary approach to integrate molecular insights with clinical applications, paving the way for more personalized and effective treatments for HHD. Addressing these challenges will not only enhance the understanding of hypertensive myocardium but also improve patient outcomes and quality of life.

Insights into the effects of apelin-13 on renal function and NHE3 activity following ischemia/reperfusion-induced acute kidney injury

Introduction

Acute kidney injury (AKI) is a clinical syndrome characterized by rapid decline in renal function with varying severity. In this context, tubular function is impaired in ischemia-induced AKI. Although there are no effective therapies for AKI, many compounds have been reported to reduce kidney injury, such as apelin-13. Considering the relevance of proximal tubular cells in maintaining fluid and electrolyte homeostasis, the effects of apelin-13 on tubular injury or sodium proximal transport remain unclear. Thus, the present study aims to evaluate the effects of exogenous administration of apelin-13 in the renal ischemia/reperfusion (I/R) model, with particular focus on renal function, injury markers, and tubular proliferation.

Methods

Male C57BL/6 mice were initially treated with a vehicle or high dose of apelin-13 (200 μg/kg/day) and subjected to kidney bilateral ischemia procedure for 30 min or a sham surgery. The mice were euthanized by exsanguination 2 d after the ischemic procedure. Then, the renal function was assessed through the plasma urea level and creatinine clearance. Tubular injury was evaluated by hematoxylin and eosin staining. Kidney injury molecule 1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), megalin, Ki67, and phospho ERK 1/2 (Thr202/Tyr204) were evaluated through immunohistochemical or immunoblotting experiments. Moreover, the murine proximal tubular cells (TKPTS) were treated with apelin-13 (100 nM) to evaluate the activity of the Na+/H+ exchanger isoform 3 (NHE3) via intracellular pH measurements.

Results

Initial administration of apelin-13 did not improve tubular injury, creatinine clearance, or plasma urea level after renal I/R. Moreover, KIM-1 and NGAL markers were markedly increased after renal I/R and were not reduced in the apelin-13 + I/R group. Furthermore, megalin downregulation by renal I/R was not prevented by apelin-13. Interestingly, apelin-13 worsened the renal responses to tubular proliferation after renal I/R as Ki67 and phosphorylation of ERK/1/2 (Thr202/Tyr204) were sharply reduced in the apelin-13 + I/R group. In vitro experiments also demonstrated that apelin-13 inhibited NHE3 activity in murine proximal tubular cells.

Conclusion

The overall findings suggest that apelin-13 suppresses tubular proliferation and potentially impairs the adaptive response to renal I/R injury, thereby highlighting its relevance in ischemia-induced AKI.

Circulating apelin levels fail to link sarcopenia-related muscle parameters in older adults

BACKGROUND

Based on the compelling experimental evidence supporting apelin's beneficial effects on muscle metabolism, our study aimed to evaluate the role of circulating apelin levels as a biomarker for muscle health in humans.

METHODS

This investigation employed a cross-sectional design, encompassing 237 community-dwelling older adults aged ≥65 years who underwent comprehensive geriatric evaluations in South Korea. Sarcopenia diagnosis was based on Asian-specific criteria, and serum apelin concentrations were determined using enzyme immunoassay techniques.

RESULTS

Following adjustment for potential confounding factors, no significant disparities in serum apelin levels were observed between sarcopenic and non-sarcopenic individuals, nor were differences detected based on skeletal muscle mass, strength, or physical performance categories (P = 0.335 to 0.765). Furthermore, circulating apelin concentrations showed no significant correlations with any sarcopenia assessment metrics, including skeletal muscle index, grip strength, gait speed, chair stand test duration, or short physical performance battery score (P = 0.170 to 0.832). Elevations in serum apelin levels were not significantly associated with the risk of sarcopenia or compromised muscle phenotypes (P = 0.452 to 0.896). Additionally, stratification of participants into quartiles based on serum apelin concentrations revealed no significant variations in sarcopenia-related parameters across groups (P = 0.197 to 0.592).

CONCLUSION

These findings suggest that, contrary to previous studies in cellular and animal models where apelin demonstrated a protective impact on muscle homeostasis, such effects may not translate to the human context, and contribute valuable clinical evidence indicating that serum apelin may not serve as a reliable biomarker for sarcopenia.

Cxcl9 modulates aging associated microvascular metabolic and angiogenic dysfunctions in subcutaneous adipose tissue

Microvascular aging, predominantly driven by endothelial cells (ECs) dysfunction, is a critical early event in cardiovascular diseases. However, the specific effects of aging on ECs across the microvascular network segments and the associated mechanisms are not fully understood. In this study, we detected a microvascular rarefaction and a decreased proportion of venular ECs in the subcutaneous adipose tissue of aged mice using light-sheet immunofluorescence microscopy and single-cell RNA sequencing. Moreover, aged ECs, especially in the venular subtype, exhibited a pseudotemporal transition to a terminal state characterized by diminished oxidative phosphorylation and strengthened cytokine signaling. Metabolic flux balance analysis predicted that among the 13 differentially expressed cytokines identified in aged EC subpopulations, Cxcl9 was strongly correlated with impaired oxidative phosphorylation in aged ECs. It was further validated using microvascular ECs treated with Cxcl9. Notably, the G protein-coupled receptor signaling pathway was subsequently suppressed, in which Aplnr suppression was also observed in aged ECs, contributing to their impaired energy metabolism and reduced angiogenesis. Based on these findings, we propose Cxcl9 as a biomarker for aging-related dysfunction of microvascular ECs, suggesting that targeting Cxcl9 signaling may help combat microvascular aging.

Apelin Receptor Homodimerisation Inhibits Hippocampal Neuronal Autophagy via G Protein-Dependent Signalling in Vascular Dementia

Vascular dementia (VD), a progressive vascular cognitive impairment, is characterised by the presence of cerebral hypoperfusion, increased blood-brain barrier permeability, and white matter lesions. Although current treatment strategies primarily focus on risk factors such as hypertension, diabetes, and heart disease, efficient and targeted therapies are lacking and the underlying mechanisms of VD remain unclear. We previously discovered that Apelin receptors (APJ), which are G protein-coupled receptors (GPCRs), can homodimerize and generate signals that are distinct from those of APJ monomers in VD rats. Apelin-13 reduces the level of APJ homodimers and leads to the proliferation of endogenous neural stem cells in the hippocampal dentate gyrus area, suggesting that it has a neuroprotective role. In this study, we established a rat and cellular oxygen-glucose deprivation/reoxygenation VD model to investigate the impact of APJ homodimerisation on autophagy. We found that APJ homodimers protect against VD by inhibiting autophagy through the Gαq and PI3K/Akt/mTOR pathways upon Gαi signalling, both in vivo and in vitro. This discovery provides a promising therapeutic target for chronic cerebral ischaemia-reperfusion diseases and an experimental foundation for the development of drugs that target APJ homodimers.

A high-fat plus high-sucrose diet induces age-related macular degeneration in an experimental rabbit model

Age-related macular degeneration (AMD) is a leading cause of blindness. Metabolic disorders and diets are risk factors. We compared lipid profiles and retinal phenotypes with long-term feeding of four diets in male Chinchilla rabbits. Animals were fed a normal diet (ND), high-fat diet (HFD), high-sucrose diet (HSD) or a high-fat plus high-sucrose diet (HFSD) for 6 months. Eyes were examined using multimodal imaging modalities and electroretinograms. Retinal sections were analyzed using H&E staining, Toluidine Blue staining, immunostaining and transmission electron microscopy. Lipids and complement C3 protein (C3) in serum or aqueous humor were measured. RNA sequencing was performed to evaluate the retinal transcriptomes. HFD and HSD had minor effects on lipid profiles but, when fed concomitantly, synergistically induced severe dyslipidemia. None of the four diets caused obesity. HFSD induced retinal lesions, such as reticular pseudodrusen (RPDs) and other pigmentary abnormalities. RPD-like lesions were mainly lipid droplets around cells of the retinal pigment epithelium. HFSD also induced elevated levels of ocular C3 and reduced the density of retinal vessels. In conclusion, HFD and HSD can - when combined - induce normal-weight dyslipidemia and RPD-like retinal lesions. HFSD-fed male Chinchilla rabbits are a good model of early AMD.

Multi-scalar data integration decoding risk genes for chronic kidney disease

BACKGROUND

Chronic Kidney Disease (CKD) impacts over 10% of the global population, and recent advancements in high-throughput analytical technologies are uncovering the complex physiology underlying this condition. By integrating Genome-Wide Association Studies (GWAS), RNA sequencing (RNA-seq/RNA array), and single-cell RNA sequencing (scRNA-seq) data, our study aimed to explore the genes and cell types relevant to CKD traits.

METHODS

GWAS summary data for end-stage renal failure (ESRD) and decreased eGFR (CKD) with or without diabetes and (micro)proteinuria were obtained from the GWAS Catalog and the UK Biobank (UKB) database. Two gene Expression Omnibus (GEO) transcriptome datasets were used to establish glomerular and tubular gene expression differences between CKD patients and healthy individuals. Two scRNA-seq datasets were utilized to obtain the expression of key genes at the single-cell level. The expression profile, differentially expressed genes (DEGs), gene-gene interaction, and pathway enrichment were analysed for these CKD risk genes.

RESULTS

A total of 779 distinct SNPs were identified from GWAS across different CKD traits, involving 681 genes. While many of these risk genes are specific to the CKD traits of renal failure, decreased eGFR, and (micro)proteinuria, they share common pathways, including extracellular matrix (ECM). ECM modeling was enriched in upregulated glomerular and tubular DEGs from CKD kidneys compared to healthy controls, with the expression of relevant collagen genes, such as COL1A2, prevalent in fibroblasts/myofibroblasts. Additionally, immune responses, including T cell differentiation, were dysregulated in CKD kidneys. The late podocyte signature gene THSD7A was enriched in podocytes but downregulated in CKD. We also highlighted that the regulated risk genes of CKD are mainly expressed in tubular cells and immune cells in the kidney.

CONCLUSIONS

Our integrated analysis highlight the genes, pathways, and relevant cell types associational with the pathogenesis of kidney traits, as a basis for further mechanistic studies to understand the pathogenesis of CKD.

Apelin-13's Actions in Controlling Hypertension-Related Cardiac Hypertrophy and the Expressions of Inflammatory Cytokines

As a key molecule for improving cardiovascular diseases, Apelin-13 was surveyed in this work to explain its actions in controlling inflammation, pyroptosis, and myocardial hypertrophy. First, mouse models with myocardial hypertrophy were established. Then, assessments were made on the pathological variation in the heart of mouse, on the cardiac functions, as well as on the expressions of cardiac hypertrophy markers (β-MHC, ANP, and BNP), inflammatory factors (TNF-α, COX2, IL-6, ICAM-1, and VCAM-1), myocardial cell pyroptosis markers (NLRP3, ASC, c-caspase-1, and GSDMD-N), and Hippo pathway proteins (p-YAP, YAP, LATS1, and p-LATS1) by HE staining, echocardiography scanning, and western blot tests separately. The expressions of such inflammatory factors as in myocardial tissue were acquired by ELISA. After inducing the phenotype of H9c2 cell hypertrophy by noradrenaline, we used CCK-8 kits to know about the activity of H9c2 cells treated with Apelin-13, and performed ɑ-actinin staining to measure the changes in volumes of such cells. As unraveled through this work, Apelin-13 refrained the activation of the Hippo pathway, which in turn attenuated the hypertrophy, inflammation, and pyroptosis of myocardial tissue and H9c2 cells. Hence, Apelin-13 can be considered as a target for hypertension treatment.

RNA-Seq-Based Transcriptome Analysis of Chinese Cordyceps Aqueous Extracts Protective Effect against Adriamycin-Induced mpc5 Cell Injury

Pharmacogenomic analysis based on drug transcriptome characteristics is widely used to identify mechanisms of action. The purpose of this study was to elucidate the molecular mechanism of protective effect against adriamycin (ADM)-induced mpc5 cell injury of Chinese cordyceps aqueous extracts (WCCs) by a systematic transcriptomic analysis. The phytochemicals of WCCs were analyzed via the "phenol-sulfuric acid method", high-performance liquid chromatography (HPLC), and HPLC-mass spectrometry (MS). We analyzed the drug-reaction transcriptome profiles of mpc5 cell after treating them with WCCs. RNA-seq analysis revealed that WCCs alleviated ADM-induced mpc5 cell injury via restoring the expression of certain genes to normal level mainly in the one-carbon pool by the folate pathway, followed by the relaxin, apelin, PI3K-Akt, and nucleotide-binding, oligomerization domain (NOD)-like receptor signaling pathway, enhancing DNA synthesis and repair, cell proliferation, fibrosis reduction, and immune regulation. Otherwise, WCCs also modulated the proliferation and survival of the mpc5 cell by regulating metabolic pathways, and partially restores the expression of genes related to human disease pathways. These findings provide an innovative understanding of the molecular mechanism of the protective effect of WCCs on ADM-induced mpc5 cell injury at the molecular transcription level, and Mthfd2, Dhfr, Atf4, Creb5, Apln, and Serpine1, etc., may be potential novel targets for treating nephrotic syndrome.

How Can Promoting Skeletal Muscle Health and Exercise in Children and Adolescents Prevent Insulin Resistance and Type 2 Diabetes?

Skeletal muscle secretome, through its paracrine and endocrine functions, contributes to the maintenance and regulation of overall physiological health. We conducted a narrative review on the role of skeletal muscle and exercise in maintaining glucose homeostasis, driving insulin resistance (IR), and preventing type 2 diabetes in pediatric populations, especially in the context of overweight and obesity. Myokines such as interleukin (IL)-6, IL-8, and IL-15, as well as irisin, myonectin, and myostatin, appear to play a crucial role in IR. Skeletal muscle can also become a target of obesity-induced and IR-induced inflammation. In the correlation between muscle, IR, and inflammation, the role of infiltration of the immune cells and the microvasculature may also be considered. It remains unclear which exercise approach is the best; however, combining aerobic exercise with resistance training seems to be the most effective strategy for managing IR, with high-intensity activities offering superior metabolic benefits and long-term adherence. Encouraging daily participation in enjoyable and engaging exercise is key for long-term commitment and effective glucose metabolism management. Promoting physical activity in children and adolescents must be a top priority for public health, not only in terms of individual quality of life and well-being but also for community health.

Microparticle Mediated Delivery of Apelin Improves Heart Function in Post Myocardial Infarction Mice

BACKGROUND

Apelin is an endogenous prepropeptide that regulates cardiac homeostasis and various physiological processes. Intravenous injection has been shown to improve cardiac contractility in patients with heart failure. However, its short half-life prevents studying its impact on left ventricular remodeling in the long term. Here, we aim to study whether microparticle-mediated slow release of apelin improves heart function and left ventricular remodeling in mice with myocardial infarction (MI).

METHODS

A cardiac patch was fabricated by embedding apelin-containing microparticles in a fibrin gel scaffold. MI was induced via permanent ligation of the left anterior descending coronary artery in adult C57BL/6J mice followed by epicardial patch placement immediately after (acute MI) or 28 days (chronic MI) post-MI. Four groups were included in this study, namely sham, MI, MI plus empty microparticle-embedded patch treatment, and MI plus apelin-containing microparticle-embedded patch treatment. Cardiac function was assessed by transthoracic echocardiography. Cardiomyocyte morphology, apoptosis, and cardiac fibrosis were evaluated by histology. Cardioprotective pathways were determined by RNA sequencing, quantitative polymerase chain reaction, and Western blot.

RESULTS

The level of endogenous apelin was largely reduced in the first 7 days after MI induction and it was normalized by day 28. Apelin-13 encapsulated in poly(lactic-co-glycolic acid) microparticles displayed a sustained release pattern for up to 28 days. Treatment with apelin-containing microparticle-embedded patch inhibited cardiac hypertrophy and reduced scar size in both acute and chronic MI models, which is associated with improved cardiac function. Data from cellular and molecular analyses showed that apelin inhibits the activation and proliferation of cardiac fibroblasts by preventing transforming growth factor-β-mediated activation of Smad2/3 (supporessor of mothers against decapentaplegic 2/3) and downstream profibrotic gene expression.

CONCLUSIONS

Poly(lactic-co-glycolic acid) microparticles prolonged the apelin release time in the mouse hearts. Epicardial delivery of the apelin-containing microparticle-embedded patch protects mice from both acute and chronic MI-induced cardiac dysfunction, inhibits cardiac fibrosis, and improves left ventricular remodeling.

Inflammatory Intracellular Signaling in Neurons Is Influenced by Glial Soluble Factors in iPSC-Based Cell Model of PARK2-Associated Parkinson's Disease

Neuroinflammation is considered to be one of the driving factors in Parkinson's disease (PD). This study was conducted using neuronal and glial cell cultures differentiated from induced pluripotent stem cells (iPSC) of healthy donors (HD) and PD patients with different PARK2 mutations (PD). Based on the results of RNA sequencing, qPCR and ELISA, we revealed transcriptional and post-transcriptional changes in HD and PD neurons cultivated in HD and PD glial-conditioned medium. We demonstrated that if one or both of the components of the system, neurons or glia, is Parkin-deficient, the interaction resulted in the down-regulation of a number of key genes related to inflammatory intracellular pathways and negative regulation of apoptosis in neurons, which might be neuroprotective. In PD neurons, the stress-induced up-regulation of APLNR was significantly stronger compared to HD neurons and was diminished by glial soluble factors, both HD and PD. PD neurons in PD glial conditioned medium increased APLN expression and also up-regulated apelin synthesis and release into intracellular fluid, which represented another compensatory action. Overall, the reported results indicate that neuronal self-defense mechanisms contribute to cell survival, which might be characteristic of PD patients with Parkin-deficiency.

Mechanisms of Bleomycin-induced Lung Fibrosis: A Review of Therapeutic Targets and Approaches

Pulmonary toxicity is a serious side effect of some specific anticancer drugs. Bleomycin is a well-known anticancer drug that triggers severe reactions in the lungs. It is an approved drug that may be prescribed for the treatment of testicular cancers, Hodgkin's and non-Hodgkin's lymphomas, ovarian cancer, head and neck cancers, and cervical cancer. A large number of experimental studies and clinical findings show that bleomycin can concentrate in lung tissue, leading to massive oxidative stress, alveolar epithelial cell death, the proliferation of fibroblasts, and finally the infiltration of immune cells. Chronic release of pro-inflammatory and pro-fibrotic molecules by immune cells and fibroblasts leads to pneumonitis and fibrosis. Both fibrosis and pneumonitis are serious concerns for patients who receive bleomycin and may lead to death. Therefore, the management of lung toxicity following cancer therapy with bleomycin is a critical issue. This review explains the cellular and molecular mechanisms of pulmonary injury following treatment with bleomycin. Furthermore, we review therapeutic targets and possible promising strategies for ameliorating bleomycin-induced lung injury.

Reciprocal Interactions Between Apelin and Noncoding RNAs in Cancer Progression

Apelin, a bioactive peptide that serves as an endogenous ligand for the apelin receptor (APJ), is overexpressed in various types of cancers and contributes to cancer cell proliferation, viability, migration, angiogenesis, and metastasis, as well as immune deviation. Noncoding RNAs (ncRNAs) regulate gene expression, and there is growing evidence suggesting a bidirectional crosstalk between ncRNAs (including long noncoding RNAs [lncRNAs], circular RNAs [circRNAs], and microRNAs [miRNAs]) and apelin in cancers. Certain miRNAs can directly target the apelin and inhibit its expression, thereby suppressing tumor growth. It has been indicated that miR-224, miR-195/miR-195-5p, miR-204-5p, miR-631, miR-4286, miR-637, miR-4493, and miR-214-3p target apelin mRNA and influence its expression in prostate cancer, lung cancer, esophageal cancer, chondrosarcoma, melanoma, gastric cancer, glioma, and hepatocellular carcinoma (HCC), respectively. Moreover, circ-NOTCH1, circ-ZNF264, and lncRNA BACE1-AS upregulate apelin expression in gastric cancer, glioma, and HCC, respectively. On the other hand, apelin has been shown to regulate the expression of certain ncRNAs to affect tumorigenesis. It was revealed that apelin affects the expression of circ_0000004/miR-1303, miR-15a-5p, and miR-106a-5p in osteosarcoma, lung cancer, and prostate cancer, respectively. This review explains a bidirectional interplay between ncRNAs and apelin in cancers to provide insights concerning the molecular mechanisms underlying this crosstalk and potential implications for cancer therapy.

Apelin - A New Kid on the Block in Periodontology

Periodontitis is associated with numerous systemic diseases, and it has been shown that these associations are partly causal in nature. It is assumed that such interactions between periodontal and systemic diseases are also medi- ated via adipokines. Apelin, an adipokine about which there is little research in the dental field, is also produced together with its receptor in periodontal cells. The aim of this review was to summarize the currently available literature on the apelin-APJ system to better understand the pathomechanistic relationship between periodontitis and obesity and to de- termine the potential clinical relevance of apelin for diagnostics and therapy. In vitro studies suggest that apelin can en- hance bacterial-induced synthesis of proinflammatory and proteolytic molecules, indicating a significant etiopathogenic role of this adipokine. Since serum levels of apelin are elevated in diabetes and/or obesity, it is possible that such sys- temic diseases promote the development and progression of periodontitis via apelin. On the other hand, it is also conceivable that apelin from the periodontium influences such systemic diseases. Further research is needed to better understand the role of apelin in the periodontium and the entire oral cavity, but also in the interactions between periodontal and sys- temic diseases. In particular, clinical intervention studies are needed to further decipher the etiopathogenic role of apelin in periodontitis.

Apelin-13 administration allows for norepinephrine sparing in a rat model of cecal ligation and puncture-induced septic shock

BACKGROUND

Infusion of exogenous catecholamines (i.e., norepinephrine [NE] and dobutamine) is a recommended treatment for septic shock with myocardial dysfunction. However, sustained catecholamine infusion is linked to cardiac toxicity and impaired responsiveness. Several pre-clinical and clinical studies have investigated the use of alternative vasopressors in the treatment of septic shock, with limited benefits and generally no effect on mortality. Apelin-13 (APL-13) is an endogenous positive inotrope and vasoactive peptide and has been demonstrated cardioprotective with vasomodulator and sparing life effects in animal models of septic shock. A primary objective of this study was to evaluate the NE-sparing effect of APL-13 infusion in an experimental sepsis-induced hypotension.

METHODS

For this goal, sepsis was induced by cecal ligation and puncture (CLP) in male rats and the arterial blood pressure (BP) monitored continuously via a carotid catheter. Monitoring, fluid resuscitation and experimental treatments were performed on conscious animals. Based on pilot assays, normal saline fluid resuscitation (2.5 mL/Kg/h) was initiated 3 h post-CLP and maintained up to the endpoint. Thus, titrated doses of NE, with or without fixed-doses of APL-13 or the apelin receptor antagonist F13A co-infusion were started when 20% decrease of systolic BP (SBP) from baseline was achieved, to restore SBP values ≥ 115 ± 1.5 mmHg (baseline average ± SEM).

RESULTS

A reduction in mean NE dose was observed with APL-13 but not F13A co-infusion at pre-determined treatment time of 4.5 ± 0.5 h (17.37 ± 1.74 µg/Kg/h [APL-13] vs. 25.64 ± 2.61 µg/Kg/h [Control NE] vs. 28.60 ± 4.79 µg/Kg/min [F13A], P = 0.0491). A 60% decrease in NE infusion rate over time was observed with APL-13 co-infusion, (p = 0.008 vs NE alone), while F13A co-infusion increased the NE infusion rate over time by 218% (p = 0.003 vs NE + APL-13). Associated improvements in cardiac function are likely mediated by (i) enhanced left ventricular end-diastolic volume (0.18 ± 0.02 mL [Control NE] vs. 0.30 ± 0.03 mL [APL-13], P = 0.0051), stroke volume (0.11 ± 0.01 mL [Control NE] vs. 0.21 ± 0.01 mL [APL-13], P < 0.001) and cardiac output (67.57 ± 8.63 mL/min [Control NE] vs. 112.20 ± 8.53 mL/min [APL-13], P = 0.0036), and (ii) a reduced effective arterial elastance (920.6 ± 81.4 mmHg/mL/min [Control NE] vs. 497.633.44 mmHg/mL/min. [APL-13], P = 0.0002). APL-13 administration was also associated with a decrease in lactate levels compared to animals only receiving NE (7.08 ± 0.40 [Control NE] vs. 4.78 ± 0.60 [APL-13], P < 0.01).

CONCLUSION

APL-13 exhibits NE-sparing benefits in the treatment of sepsis-induced shock, potentially reducing deleterious effects of prolonged exogenous catecholamine administration.

Exploring the multifaceted role of obesity in breast cancer progression

Obesity is a multifaceted metabolic disorder characterized by excessive accumulation of adipose tissue. It is a well-established risk factor for the development and progression of breast cancer. Adipose tissue, which was once regarded solely as a passive energy storage depot, is now acknowledged as an active endocrine organ producing a plethora of bioactive molecules known as adipokines that contribute to the elevation of proinflammatory cytokines and estrogen production due to enhanced aromatase activity. In the context of breast cancer, the crosstalk between adipocytes and cancer cells within the adipose microenvironment exerts profound effects on tumor initiation, progression, and therapeutic resistance. Moreover, adipocytes can engage in direct interactions with breast cancer cells through physical contact and paracrine signaling, thereby facilitating cancer cell survival and invasion. This review endeavors to summarize the current understanding of the intricate interplay between adipocyte-associated factors and breast cancer progression. Furthermore, by discussing the different aspects of breast cancer that can be adversely affected by obesity, this review aims to shed light on potential avenues for new and novel therapeutic interventions.

Potential Involvement of Apelin/APJ System in Addiction and Neuroprotection Against Drugs of Abuse

Addiction, characterized by compulsive drug-seeking behavior and impaired self-control, remains a significant public health concern. Understanding the neurobiology of addiction is crucial for identifying novel therapeutic targets and further developing effective treatments. Recently, the apelin/APJ system, an emerging signaling pathway, has attracted attention for its involvement in various neuropsychiatric disorders. The cross-talk between the apelin/APJ system and hypothalamic mu opioid signaling, as well as its heterodimerization with kappa opioid receptors (KORs), supports the potential relevance of this system to addiction. Moreover, several protective effects of apelin against various addictive substances, including methamphetamine, morphine, and alcohol, underscore the need for further investigation into its role in substance use disorder. Understanding the contribution of the apelin/APJ system in addiction may offer valuable insights into the underlying neurobiology and pave the way for novel therapeutic interventions in substance use disorders. This review provides a concise overview of the apelin/APJ system, emphasizing its physiological roles and highlighting its relevance to addiction research.

The role of asprosin in regulating ovarian granulosa- and theca-cell steroidogenesis: a review with comparisons to other adipokines

Adipose tissues produce a variety of biologically active compounds, including cytokines, growth factors and adipokines. Adipokines are important as they function as endocrine hormones that are related to various metabolic and reproductive diseases. The goal of this review was to summarise the role of asprosin, a recently discovered adipokine, and compare its role in ovarian steroidogenesis with that of other adipokines including adiponectin, leptin, resistin, apelin, visfatin, chemerin, irisin, and gremlin 1. The summary of concentrations of these adipokines in humans, rats and other animals will help researchers identify appropriate doses to test in future studies. Review of the literature indicated that asprosin increases androstenedione production in theca cells (Tc), and when cotreated with FSH increases oestradiol production in granulosa cells (Gc). In comparison, other adipokines (1) stimulate Gc oestradiol production but inhibit Tc androgen production (adiponectin), (2) inhibit Gc oestradiol production and Tc androstenedione production (leptin and chemerin), (3) inhibit Gc steroidogenesis with no effect on Tc (resistin), (4) inhibit Gc oestradiol production but stimulate Tc androgen production (gremlin 1), and (5) increase steroid secretion by Gc, with unknown effects on Tc steroidogenesis (apelin and visfatin). Irisin has direct effects on Gc but its precise role (inhibitory or stimulatory) may be species dependent and its effects on Tc will require additional research. Thus, most adipokines have direct effects (either positive or negative) on steroid production in ovarian cells, but how they all work together to create a cumulative effect or disease will require further research.

The role of central neurotransmitters in appetite regulation of broilers and layers: similarities and differences

The importance of feeding as a vital physiological function, on the one hand, and the spread of complications induced by its disorder in humans and animals, on the other hand, have led to extensive research on its regulatory factors. Unfortunately, despite many studies focused on appetite, only limited experiments have been conducted on avian, and our knowledge of this species is scant. Considering this, the purpose of this review article is to examine the role of central neurotransmitters in regulating food consumption in broilers and layers and highlight the similarities and differences between these two strains. The methodology of this review study includes a comprehensive search of relevant literature on the topic using appropriate keywords in reliable electronic databases. Based on the findings, the central effect of most neurotransmitters on the feeding of broilers and laying chickens was similar, but in some cases, such as dopamine, ghrelin, nitric oxide, and agouti-related peptide, differences were observed. Also, the lack of conducting a study on the role of some neurotransmitters in one of the bird strains made it impossible to make an exact comparison. Finally, it seems that although there are general similarities in appetite regulatory mechanisms in meat and egg-type chickens, the long-term genetic selection appropriate to breeding goals (meat or egg production) has caused differences in the effect of some neurotransmitters. Undoubtedly, conducting future studies while completing the missing links can lead to a comprehensive understanding of this process and its manipulation according to the breeding purposes of chickens.

The structural analogue of apelin-12 prevents energy disorders in the heart in experimental type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) is the most severe form of diabetes, which is characterized by absolute insulin deficiency induced by the destruction of pancreatic beta cells. The aim of this study was to evaluate the effect of a structural analogue of apelin-12 ((NαMe)Arg-Pro-Arg-Leu-Ser-His-Lys-Gly-Pro-Nle-Pro-Phe-OH, metilin) on hyperglycemia, mitochondrial (MCh) respiration in permeabilized cardiac left ventricular (LV) fibers, the myocardial energy state, and cardiomyocyte membranes damage in a model of streptozotocin (STZ) diabetes in rats. Metilin was prepared by solid-phase synthesis using the Fmoc strategy and purified using HPLC. Four groups of animals were used: initial state (IS); control (C), diabetic control (D) and diabetic animals additionally treated with metilin (DM). The following parameters have been studied: blood glucose, MCh respiration in LV fibers, the content of cardiac ATP, ADP, AMP, phosphocreatine (PCr) and creatine (Cr), the activity of creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH) in blood plasma. Administration of metilin to STZ-treated rats decreased blood glucose, increased state 3 oxygen consumption, the respiratory control ratio in MCh of permeabilized LV fibers, and increased the functional coupling of mitochondrial CK (mt-CK) to oxidative phosphorylation compared with these parameters in group D. In STZ-treated animals metilin administration caused an increase in the PCr content and prevention of the loss of total creatine (ΣCr=PCr+Cr) in the diabetic hearts, as well as restoration of the PCr/ATP ratio in the myocardium and a decrease in the activity of CK-MB and LDH in plasma to initial values. Thus, metilin prevented energy disorders disturbances in cardiomyocytes of animals with experimental T1DM.

Apelin-13 modulates the endometrial transcriptome of the domestic pig during implantation

BACKGROUND

The peri-implantation period is a critical time during pregnancy that mostly defines the overall litter size. Most authors agree that the highest percentage of embryo mortality occurs during this time. Despite the brevity of the peri-implantation period, it is the most dynamic part of pregnancy in which the sequential and uninterrupted course of several processes is essential to the animal's reproductive success. Also then, the maternal uterine tissues undergo an intensive remodelling process, and their energy demand dramatically increases. It is believed that apelin, a member of the adipokine family, is involved in the control of female reproductive functions in response to the current metabolic state. The verified herein hypothesis assumed the modulatory effect of apelin on the endometrial tissue transcriptome on days 15 to 16 of gestation (beginning of implantation).

RESULTS

The analysis of data obtained during RNA-seq (Illumina HiSeq2500) of endometrial slices treated and untreated with apelin (n = 4 per group) revealed changes in the expression of 68 genes (39 up-regulated and 29 down-regulated in the presence of apelin), assigned to 240 gene ontology terms. We also revealed changes in the frequency of alternative splicing events (397 cases), as well as single nucleotide variants (1,818 cases) in the presence of the adipokine. The identified genes were associated, among others, with the composition of the extracellular matrix, apoptosis, and angiogenesis.

CONCLUSIONS

The obtained results indicate a potential role of apelin in the regulation of uterine tissue remodelling during the peri-implantation period.

Placental transcriptome variation associated with season, location, and urinary prenatal pyrethroid metabolites of Thai farm-working women

Prenatal exposure to pyrethroids is linked to adverse health effects in early life and proper placental function is critical to fetal development. This study explores the impact of prenatal pyrethroid exposure, as well as factors impacting exposure and effect, on the placental transcriptome, to understand pyrethroid exposures' relationship to placental function. The study of Asian Women and their Offspring's Development and Environmental Exposures (SAWASDEE) recruited pregnant farm-working women from two agricultural districts in the Chiang Mai province of Thailand between 2017 and 2019. This cohort was predominantly exposed to cypermethrin (type II), alongside pyrethroids such as cyfluthrin (type II) and permethrin (type I). In 253 participants, maternal urinary pyrethroid metabolites, 3-phenoxybenzoic acid (PBA), cis-3-(2,2-Dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (CDCCA), and trans-3-(2,2-Dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (TDCCA) were measured in early, middle, and late pregnancy and adjusted for urinary creatinine. The placental transcriptome was analyzed using RNA-Seq. Using generalized linear regression, we identified differentially expressed genes (DEGs) associated with the sum of each metabolite across pregnancy, as well as those associated with location of residence and season of birth. Pathway and upstream transcription factor analyses were performed to examine potential mechanisms associated with DEGs. Notably, TDCCA and CDCCA levels peaked in late pregnancy, with significant regional differences, particularly higher levels in the Fang region. Placental gene expression analysis showed no DEGs associated with individual metabolites at FDR<0.05. However, 251 DEGs by location, implicating immune response and oxidative phosphorylation pathways, were identified, while season of birth was associated with 2585 DEGs, over-represented in fibrosis signaling and metabolism pathways. Finally, transcription factor analysis identified 226 and 282 transcription factors associated with location and season, respectively, related to cell proliferation, differentiation, and the immune system. These alterations may have significant implications for fetal development and other pathologic processes, highlighting the importance of monitoring environmental exposures during pregnancy.

The Neglected Sibling: NLRP2 Inflammasome in the Nervous System

While classical NOD-like receptor pyrin domain containing protein 1 (NLRP1) and NLRP3 inflammasomal proteins have been extensively investigated, the contribution of NLRP2 is still ill-defined in the nervous system. Given the putative significance of NLRP2 in orchestrating neuroinflammation, further inquiry is needed to gain a better understanding of its connectome, hence its specific targeting may hold a promising therapeutic implication. Therefore, bioinformatical approach for extracting information, specifically in the context of neuropathologies, is also undoubtedly preferred. To the best of our knowledge, there is no review study selectively targeting only NLRP2. Increasing, but still fragmentary evidence should encourage researchers to thoroughly investigate this inflammasome in various animal- and human models. Taken together, herein we aimed to review the current literature focusing on the role of NLRP2 inflammasome in the nervous system and more importantly, we provide an algorithm-based protein network of human NLRP2 for elucidating potentially valuable molecular partnerships that can be the beginning of a new discourse and future therapeutic considerations.

New Mediators in the Crosstalk between Different Adipose Tissues

Adipose tissue is a multifunctional organ that regulates many physiological processes such as energy homeostasis, nutrition, the regulation of insulin sensitivity, body temperature, and immune response. In this review, we highlight the relevance of the different mediators that control adipose tissue activity through a systematic review of the main players present in white and brown adipose tissues. Among them, inflammatory mediators secreted by the adipose tissue, such as classical adipokines and more recent ones, elements of the immune system infiltrated into the adipose tissue (certain cell types and interleukins), as well as the role of intestinal microbiota and derived metabolites, have been reviewed. Furthermore, anti-obesity mediators that promote the activation of beige adipose tissue, e.g., myokines, thyroid hormones, amino acids, and both long and micro RNAs, are exhaustively examined. Finally, we also analyze therapeutic strategies based on those mediators that have been described to date. In conclusion, novel regulators of obesity, such as microRNAs or microbiota, are being characterized and are promising tools to treat obesity in the future.

Influence of Adipokines on Metabolic Dysfunction and Aging

Currently, 30% of the global population is overweight or obese, with projections from the World Obesity Federation suggesting that this figure will surpass 50% by 2035. Adipose tissue dysfunction, a primary characteristic of obesity, is closely associated with an increased risk of metabolic abnormalities, such as hypertension, hyperglycemia, and dyslipidemia, collectively termed metabolic syndrome. In particular, visceral fat accretion is considered as a hallmark of aging and is strongly linked to higher mortality rates in humans. Adipokines, bioactive peptides secreted by adipose tissue, play crucial roles in regulating appetite, satiety, adiposity, and metabolic balance, thereby rendering them key players in alleviating metabolic diseases and potentially extending health span. In this review, we elucidated the role of adipokines in the development of obesity and related metabolic disorders while also exploring the potential of certain adipokines as candidates for longevity interventions.

Effects of aerobic exercise on blood pressure in patients with hypertension: a systematic review and dose-response meta-analysis of randomized trials

We aimed to evaluate the dose-dependent effects of aerobic exercise on systolic (SBP) and diastolic blood pressure (DBP) and haemodynamic factors in adults with hypertension. PubMed, Scopus, and Web of Science were searched to April 2022 for randomized trials of aerobic exercise in adults with hypertension. We conducted a random-effects meta-analysis to estimate mean differences (MDs) and 95%CIs for each 30 min/week increase in aerobic exercise. The certainty of evidence was rated using the GRADE approach. The analysis of 34 trials with 1787 participants indicated that each 30 min/week aerobic exercise reduced SBP by 1.78 mmHg (95%CI: -2.22 to -1.33; n = 34, GRADE=low), DBP by 1.23 mmHg (95%CI: -1.53 to -0.93; n = 34, GRADE=moderate), resting heart rate (MD = -1.08 bpm, 95%CI: -1.46 to -0.71; n = 23, GRADE=low), and mean arterial pressure (MD = -1.37 mmHg, 95%CI: -1.80 to -0.93; n = 9, GRADE = low). A nonlinear dose-dependent decrement was seen on SBP and DBP, with the greatest decrement at 150 min/week (MD150 min/week = -7.23 mmHg, 95%CI: -9.08 to -5.39 for SBP and -5.58 mmHg, 95%CI: -6.90 to -4.27 for DBP). Aerobic exercise can lead to a large and clinically important reduction in blood pressure in a dose-dependent manner, with the greatest reduction at 150 min/week. The dose-dependent effects of aerobic exercise on systolic and diastolic blood pressure and haemodynamic factors in adults with hypertension.

Serum apelin-12 and obesity-related markers in Egyptian children with Down syndrome

Children with Down syndrome (DS) exhibit higher overweight/obesity rates than their typically developing peers. Apelin-12 is a bioactive adipokine that exerts vital roles in obesity-related cardiometabolic comorbidities. To date, apelin-12 has not been investigated in obese-DS. This study aimed to explore the possible association between serum apelin-12 and obesity-related markers and to evaluate the efficiency of apelin-12 in the prediction of metabolic syndrome (MetS) in obese-DS compared to BMI Z-score matched obese-control. The cross-sectional study included 150 prepubertal children classified into three groups; obese-DS (n = 50), obese-control (n = 50), and normal-weight-control (n = 50). Anthropometric parameters, body adiposity, fasting serum levels of blood glucose (FBG), insulin, lipid profile, and apelin-12 were evaluated. Homeostasis model assessment of insulin resistance (HOMA-IR) was calculated from FBG and insulin. MetS was defined using Adult Treatment Panel III criteria modified for the pediatric age group. ROC curves were analyzed to evaluate the efficiency of apelin-12 in predicting MetS in obesity groups. Obese-DS exhibited higher body adiposity with marked central fat distribution, atherogenic lipid profile, and higher HOMA-IR compared to obese-control. Apelin-12 was significantly higher in obese-DS and obese-DS with MetS compared to obese-control and obese-control with MetS respectively (p < 0.001). The increase in apelin-12 with higher obesity grades was pronounced in obese-DS. Apelin-12 strongly correlated with body adiposity, several MetS risk factors, and HOMA-IR in obese-DS. Significantly higher AUC for apelin-12 in the diagnosis of MetS among obese-DS than obese-control (AUC = 0.948 vs. AUC = 0.807; p = 0.04).

CONCLUSIONS

 The current study supports the crucial role of apelin-12 in obesity-related clinical and biochemical markers and in MetS in obese-DS and obese-control. Serum apelin-12 is a potential diagnostic biomarker for MetS with greater performance in obese-DS than obese-control raising its potential for clinical and therapeutic applications.

WHAT IS KNOWN

• Obese-DS children displayed excess body adiposity, Pronounced central fat distribution, atherogenic lipid profile, higher HOMA-IR, and higher prevalence of MetS than obese-control.

WHAT IS NEW

• Higher serum apelin-12 was observed in obese-DS and obese-DS with MetS than obese-control and obese-control with MetS respectively. The increase in apelin-12 level with increasing obesity grades was more pronounced in obese-DS. • Apelin-12 strongly correlated with obesity-related markers and MetS components in obese-DS. Apelin-12 performed better as a diagnostic biomarker for MetS in obese-DS than obese-control.

Learning induces unique transcriptional landscapes in the auditory cortex

Learning can induce neurophysiological plasticity in the auditory cortex at multiple timescales. Lasting changes to auditory cortical function that persist over days, weeks, or even a lifetime, require learning to induce de novo gene expression. Indeed, transcription is the molecular determinant for long-term memories to form with a lasting impact on sound-related behavior. However, auditory cortical genes that support auditory learning, memory, and acquired sound-specific behavior are largely unknown. Using an animal model of adult, male Sprague-Dawley rats, this report is the first to identify genome-wide changes in learning-induced gene expression within the auditory cortex that may underlie long-lasting discriminative memory formation of acoustic frequency cues. Auditory cortical samples were collected from animals in the initial learning phase of a two-tone discrimination sound-reward task known to induce sound-specific neurophysiological and behavioral effects. Bioinformatic analyses on gene enrichment profiles from bulk RNA sequencing identified cholinergic synapse (KEGG rno04725), extra-cellular matrix receptor interaction (KEGG rno04512), and neuroactive receptor interaction (KEGG rno04080) among the top biological pathways are likely to be important for auditory discrimination learning. The findings characterize candidate effectors underlying the early stages of changes in cortical and behavioral function to ultimately support the formation of long-term discriminative auditory memory in the adult brain. The molecules and mechanisms identified are potential therapeutic targets to facilitate experiences that induce long-lasting changes to sound-specific auditory function in adulthood and prime for future gene-targeted investigations.

The Interplay of Adipokines and Pancreatic Beta Cells in Metabolic Regulation and Diabetes

The interplay between adipokines and pancreatic beta cells, often referred to as the adipo-insular axis, plays a crucial role in regulating metabolic homeostasis. Adipokines are signaling molecules secreted by adipocytes that have profound effects on several physiological processes. Adipokines such as adiponectin, leptin, resistin, and visfatin influence the function of pancreatic beta cells. The reciprocal communication between adipocytes and beta cells is remarkable. Insulin secreted by beta cells affects adipose tissue metabolism, influencing lipid storage and lipolysis. Conversely, adipokines released from adipocytes can influence beta cell function and survival. Chronic obesity and insulin resistance can lead to the release of excess fatty acids and inflammatory molecules from the adipose tissue, contributing to beta cell dysfunction and apoptosis, which are key factors in developing type 2 diabetes. Understanding the complex interplay of the adipo-insular axis provides insights into the mechanisms underlying metabolic regulation and pathogenesis of metabolic disorders. By elucidating the molecular mediators involved in this interaction, new therapeutic targets and strategies may emerge to reduce the risk and progression of diseases, such as type 2 diabetes and its associated complications. This review summarizes the interactions between adipokines and pancreatic beta cells, and their roles in the pathogenesis of diabetes and metabolic diseases.

Learning induces unique transcriptional landscapes in the auditory cortex

Learning can induce neurophysiological plasticity in the auditory cortex at multiple timescales. Lasting changes to auditory cortical function that persist over days, weeks, or even a lifetime, require learning to induce de novo gene expression. Indeed, transcription is the molecular determinant for long-term memories to form with a lasting impact on sound-related behavior. However, auditory cortical genes that support auditory learning, memory, and acquired sound-specific behavior are largely unknown. This report is the first to identify in young adult male rats (Sprague-Dawley) genome-wide changes in learning-induced gene expression within the auditory cortex that may underlie the formation of long-lasting discriminative memory for acoustic frequency cues. Auditory cortical samples were collected from animals in the initial learning phase of a two-tone discrimination sound-reward task known to induce sound-specific neurophysiological and behavioral effects (e.g., Shang et al., 2019). Bioinformatic analyses on gene enrichment profiles from bulk RNA sequencing identified cholinergic synapse (KEGG 04725), extra-cellular matrix receptor interaction (KEGG 04512) , and neuroactive ligand-receptor interaction (KEGG 04080) as top biological pathways for auditory discrimination learning. The findings characterize key candidate effectors underlying changes in cortical function that support the initial formation of long-term discriminative auditory memory in the adult brain. The molecules and mechanisms identified are potential therapeutic targets to facilitate lasting changes to sound-specific auditory function in adulthood and prime for future gene-targeted investigations.

Transcriptomics reveals key genes responsible for functional diversity in pectoralis major muscles of native black Kadaknath and broiler chicken

RNA sequencing-based expression profiles from pectoralis major muscles of black meat (Kadaknath) and white meat (broiler) chicken were compared to identify differentially expressed genes. A total of 156 genes with log2 fold change ≥  ± 2.0 showed higher expression in Kadaknath and 68 genes were expressed at a lower level in comparison to broiler. Significantly enriched biological functions of up-regulated genes in Kadaknath were skeletal muscle cell differentiation, regulation of response to reactive oxygen, positive regulation of fat cell differentiation and melanosome. Significant ontology terms up-regulated in broiler included DNA replication origin binding, G-protein coupled receptor signaling pathway and chemokine activity. Highly inter-connected differentially expressed genes in Kadaknath (ATFs, C/EPDs) were observed to be important regulators of cellular adaptive functions, while in broiler, the hub genes were involved in cell cycle progression and DNA replication. The study is an attempt to get an insight into the transcript diversity of pectoralis major muscles of Kadaknath and broiler chicken.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03682-0.

The role of apelinergic system in metabolism and reproductive system in normal and pathological conditions: an overview

Lifestyle changes have made metabolic disorders as one of the major threats to life. Growing evidence demonstrates that obesity and diabetes disrupt the reproductive system by affecting the gonads and the hypothalamus-pituitary-gonadal (HPG) axis. Apelin, an adipocytokine, and its receptor (APJ) are broadly expressed in the hypothalamus nuclei, such as paraventricular and supraoptic, where gonadotropin-releasing hormone (GnRH) is released, and all three lobes of the pituitary, indicating that apelin is involved in the control of reproductive function. Moreover, apelin affects food intake, insulin sensitivity, fluid homeostasis, and glucose and lipid metabolisms. This review outlined the physiological effects of the apelinergic system, the relationship between apelin and metabolic disorders such as diabetes and obesity, as well as the effect of apelin on the reproductive system in both gender. The apelin-APJ system can be considered a potential therapeutic target in the management of obesity-associated metabolic dysfunction and reproductive disorders.

Exercise improves homeostasis of the intestinal epithelium by activation of apelin receptor-AMP-activated protein kinase signalling

Intestinal remodelling is dynamically regulated by energy metabolism. Exercise is beneficial for gut health, but the specific mechanisms remain poorly understood. Intestine-specific apelin receptor (APJ) knockdown (KD) and wild-type male mice were randomly divided into two subgroups, with/without exercise, to obtain four groups: WT, WT with exercise, APJ KD and APJ KD with exercise. Animals in the exercise groups were subjected to daily treadmill exercise for 3 weeks. Duodenum was collected at 48 h after the last bout of exercise. AMP-activated protein kinase (AMPK) α1 KD and wild-type mice were also utilized for investigating the mediatory role of AMPK on exercise-induced duodenal epithelial development. AMPK and peroxisome proliferator-activated receptor γ coactivator-1 α were upregulated by exercise via APJ activation in the intestinal duodenum. Correspondingly, exercise induced permissive histone modifications in the PR domain containing 16 (PRDM16) promoter to activate its expression, which was dependent on APJ activation. In agreement, exercise elevated the expression of mitochondrial oxidative markers. The expression of intestinal epithelial markers was downregulated due to AMPK deficiency, and AMPK signalling facilitated epithelial renewal. These data demonstrate that exercise-induced activation of the APJ-AMPK axis facilitates the homeostasis of the intestinal duodenal epithelium. KEY POINTS: Apelin receptor (APJ) signalling is required for improved epithelial homeostasis of the small intestine in response to exercise. Exercise intervention activates PRDM16 through inducing histone modifications, enhanced mitochondrial biogenesis and fatty acid metabolism in duodenum. The morphological development of duodenal villus and crypt is enhanced by the muscle-derived exerkine apelin through the APJ-AMP-activated protein kinase axis.

APJ as Promising Therapeutic Target of Peptide Analogues in Myocardial Infarction- and Hypertension-Induced Heart Failure

The widely expressed G protein-coupled apelin receptor (APJ) is activated by two bioactive endogenous peptides, apelin and ELABELA (ELA). The apelin/ELA-APJ-related pathway has been found involved in the regulation of many physiological and pathological cardiovascular processes. Increasing studies are deepening the role of the APJ pathway in limiting hypertension and myocardial ischaemia, thus reducing cardiac fibrosis and adverse tissue remodelling, outlining APJ regulation as a potential therapeutic target for heart failure prevention. However, the low plasma half-life of native apelin and ELABELA isoforms lowered their potential for pharmacological applications. In recent years, many research groups focused their attention on studying how APJ ligand modifications could affect receptor structure and dynamics as well as its downstream signalling. This review summarises the novel insights regarding the role of APJ-related pathways in myocardial infarction and hypertension. Furthermore, recent progress in designing synthetic compounds or analogues of APJ ligands able to fully activate the apelinergic pathway is reported. Determining how to exogenously regulate the APJ activation could help to outline a promising therapy for cardiac diseases.

Betatrophin, elabela, asprosin, glucagon and subfatin peptides in breast tissue, blood and milk in gestational diabetes

We investigated the presence of asprosin (ASP), betatrophin, elabela (ELA), glucagon and subfatin (SUB) in the milk of mothers with gestational diabetes mellitus (GDM) and compared their levels with blood levels. We also investigated whether these peptides are synthesized by the breast. We investigated 12 volunteer mothers with GDM and 14 pregnant non-GDM control mothers. The peptides were measured using ELISA and their tissue localization was determined using immunohistochemistry. Breast milk contains ASP, betatrophin, ELA, glucagon and SUB. The amount of the peptides ranged from highest to the lowest in colostrum, transitional milk and mature milk. The amount of peptides in the milk was greater than for blood. The peptides, except for ELA, were increased in milk and blood by GDM. Betatrophin and ELA are synthesized in the connective tissue of the breast. ASP, glucagon and SUB are synthesized in the alveolar tissue of the breast. These peptides in breast milk may contribute to the development of the gastrointestinal tract of newborns and infants.

The Role of Selected Adipocytokines in Ovarian Cancer and Endometrial Cancer

Due to their multidirectional influence, adipocytokines are currently the subject of numerous intensive studies. Significant impact applies to many processes, both physiological and pathological. Moreover, the role of adipocytokines in carcinogenesis seems particularly interesting and not fully understood. For this reason, ongoing research focuses on the role of these compounds in the network of interactions in the tumor microenvironment. Particular attention should be drawn to cancers that remain challenging for modern gynecological oncology-ovarian and endometrial cancer. This paper presents the role of selected adipocytokines, including leptin, adiponectin, visfatin, resistin, apelin, chemerin, omentin and vaspin in cancer, with a particular focus on ovarian and endometrial cancer, and their potential clinical relevance.

The preliminary study of exosomes derived from thymosin beta 4-treated adipose-derived stem cells in fat grafting

BACKGROUND

The retention rate in autologous fat grafting is an increasing concern for surgeons and patients. Our previous research verified that thymosin beta 4 (Tβ4) positively affected fat survival, while the mechanism was unknown. The endothelial cells (ECs) and exosomes derived from adipose-derived stem cells (ADSCs) were regarded to play a critical role in fat transplantation.

OBJECTIVE

This study aimed to evaluate the effect of exosomes derived from Tβ4-treated ADSCs on EC proliferation and to identify the exosomal microRNA (miRNA) profile compared with the Tβ4-untreated group. Additionally, this research intended to recognize the related molecules and signaling pathways in the Tβ4-treated group with potential roles in fat transplants.

METHODS

ADSCs were collected from patients who underwent liposuction surgery. Depending on whether the medium was supplemented with exogenous Tβ4 or not, exosomes derived from cultured ADSCs were divided into the Tβ4-Exos group and Con-Exos group. Exosome uptake and cell counting kit-8 (CCK-8) assays assessed the influence of Tβ4-Exos on EC proliferation. The exosomal miRNAs of the two groups were analyzed by next-generation sequencing. With the criteria at the |log₂ (fold change)| ≥ 1 and p-value < 0.05, up-regulated and down-regulated differentially expressed miRNAs (DEMs) were obtained. Prediction databases were used to predict the downstream mRNAs for DEMs. And then, overlapping genes for the up-regulated DEMs and the down-regulated were screened out, followed by enrichment analysis, protein-protein interaction network construction, and the gene cluster and hub gene identification.

RESULTS

ADSCs were obtained from four female patients. The exosome uptake and CCK-8 assays showed that the Tβ4-Exos could increase cell growth rate compared with the control group (DMEM-H + PBS). In Tβ4-Exos and Con-Exos groups, 2651 exosomal miRNAs were recognized, with 80 up-regulated and 99 down-regulated DEMs according to the criteria. After the prediction, 621 overlapping genes for the up-regulated and 572 for the down-regulated DEMs were screened. The subsequent bioinformatics analysis found specific molecules and pathways related to the positive effect on fat survival.

CONCLUSIONS

The exosomes derived from Tβ4-treated ADSCs probably positively affect EC proliferation. Compared with the Con-Exos group, several exosomal DEMs, genes, and pathways were distinguished. These findings of this exploratory study provide the potential direction for future in-depth research on fat grafting.

Apelin Is a Prototype of Novel Drugs for the Treatment of Acute Myocardial Infarction and Adverse Myocardial Remodeling

In-hospital mortality in patients with ST-segment elevation myocardial infarction (STEMI) is 5-6%. Consequently, it is necessary to develop fundamentally novel drugs capable of reducing mortality in patients with acute myocardial infarction. Apelins could be the prototype for such drugs. Chronic administration of apelins mitigates adverse myocardial remodeling in animals with myocardial infarction or pressure overload. The cardioprotective effect of apelins is accompanied by blockage of the MPT pore, GSK-3β, and the activation of PI3-kinase, Akt, ERK1/2, NO-synthase, superoxide dismutase, glutathione peroxidase, matrix metalloproteinase, the epidermal growth factor receptor, Src kinase, the mitoK_ATP channel, guanylyl cyclase, phospholipase C, protein kinase C, the Na⁺/H⁺ exchanger, and the Na⁺/Ca²⁺ exchanger. The cardioprotective effect of apelins is associated with the inhibition of apoptosis and ferroptosis. Apelins stimulate the autophagy of cardiomyocytes. Synthetic apelin analogues are prospective compounds for the development of novel cardioprotective drugs.

Disinhibition augments thirst perception from two dehydrating stimuli in men

Physiological systems controlling water and energy ingestion are coordinated. Whether maladaptive eating behavior and appetite for water are linked is unknown. Thus, we sought to investigate the association between maladaptive eating and both thirst and water drinking behavior with two dehydrating conditions. Twenty-two lean men and 20 men with obesity (mean age 32.3 ± 8.4 years and 30.0 ± 11.1 years, respectively) completed the Three-Factor Eating Questionnaire (TFEQ) and Gormally Binge Eating Scale. On separate days, volunteers were dehydrated by a 2-h hypertonic saline infusion and a 24-h water deprivation, and thirst was measured on a 100-mm visual analogue scale (VAS) during each procedure. After each dehydrating condition, ad libitum water intake was measured. In the saline infusion, higher Disinhibition on the TFEQ was associated with thirst in the lean group (β = 4.2 mm VAS, p = 0.03) but not in the group with obesity (p = 0.51). In the water-deprivation condition, higher Disinhibition was also associated with thirst in the lean group (β = 5.6 mm VAS, p = 0.01) with the strength of relationship being 3.5-fold stronger than that observed in the group with obesity (β = 1.6 mm VAS, p = 0.0003). Hunger, Restraint, and binge-eating scores were not associated with thirst in either dehydrating condition (all p > 0.05). Maladaptive eating behaviors were not associated with ad libitum water intake (all p > 0.05). Disinhibition is associated with higher thirst perception in healthy weight individuals and may be attenuated in obesity. The characteristics of disinhibition which typically includes a heightened readiness to eat, may reflect a more general phenotype that also reflects a readiness to drink.

Revealment study on the regulation of lipid metabolism by Lingguizhugan Decoction in heart failure treatment based on integrated lipidomics and proteomics

Lingguizhugan Decoction (LGZGD) is a classical traditional Chinese medicine prescription. Our previous studies found that disorders of lipid metabolism were reversed by LGZGD in heart failure (HF) mice. This study aimed to reveal the regulation of lipid metabolism of LGZGD. A mice model of HF was established by intraperitoneal injection of doxorubicin. The components of LGZGD were identified with the UHPLC-QTOF-MS method. The regulation of lipid metabolism by LGZGD was detected by serum lipidomics and heart tissue proteomics. Molecular docking was further performed to screen active components. A total of 78 compounds in LGZGD were identified. Results of lipidomics showed that 37 lipids illustrated a significant recovery trend to normal after the treatment of LGZGD. Results of proteomics demonstrated that 55 proteins were altered by the administration of LGZGD in HF mice. After enrichment analysis, the Prakg2/Ucp2/Plin1 axis on the Apelin pathway plays a vital role in HF treatment by LGZGD. Nine active components exhibited the outstanding ability of binding to the apelin receptor with MM-GBSA value lower than -60 Kcal/mol. In conclusion, all results combined together revealed that multi-component in the LGZGD had beneficial effects on the HF through ameliorating lipid disorders, which provides a novel insight into the cardioprotective effects of LGZGD and its clinical application.

Is Habitual Dietary Intake of Fats Associated with Apelin Gene Expression in Visceral and Subcutaneous Adipose Tissues and Its Serum Levels in Obese Adults?

INTRODUCTION

Apelin could be one of the last protective defenses before developing obesity-related disorders, including insulin resistance, type 2 diabetes, and hypertension, which can be modified by dietary intake. The present study investigated the association of habitual intake of total fatty acids (TFAs), saturated-, monounsaturated-, polyunsaturated FAs, n-3, and n-6 FAs with Apelin expression in visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT).

METHODS

We obtained VAT and SAT from 168 participants (64 nonobese and 104 obese) who had undergone open abdominal surgery. Dietary intake information was gathered with a valid and reliable food frequency questionnaire. The mRNA expression of the Apelin gene was analyzed by real-time PCR.

RESULTS

Apelin serum levels were increased in the obese subjects compared to the nonobese group (p = 0.016). The SAT and VAT Apelin mRNA levels were significantly elevated in the obese participants compared to the nonobese ones (p < 0.05). Based on BMI status, only obese subjects indicated a positive association between SAT and VAT Apelin expression and TFA intake (p < 0.001). However, this association was observed between SAT and VAT Apelin gene expression and polyunsaturated fatty acid (PUFA) and n-3 FA intakes in both obese and nonobese groups (p < 0.05).

CONCLUSION

High Apelin gene expression was associated with TFA intake in obese subjects in both fat tissues. However, habitual intake of PUFA and n-3 FA was associated with Apelin gene expression in obese and nonobese individuals. Our results indicate a determinative role of the quality and quantity of FA intake on adipose tissue.

Research progress of apelin in acute ischemic brain injury

Acute ischemic brain injury is a cerebrovascular disease with high clinical incidence. An increasing number of preclinical evidence has verified the complex interaction between autophagy disorder and mitochondrial damage. Endoplasmic reticulum stress, oxidative stress and excessive neuroinflammation are the main mechanisms of the neural injury induced by acute cerebral ischemia-reperfusion injury. Apelin and its receptors are widely distributed in various tissues and organs in the human body. Increasing evidence has suggested that apelin has a neuroprotective effect against excitatory toxicity injury, oxidative stress injury and induction of neuronal apoptosis, and it can play a neuroprotective role after acute cerebral ischemia-reperfusion injury. This review summarizes the progress of the neuroprotective effects and mechanisms of apelin, aiming to provide evidence for its therapeutic potential.

Elabela Peptide: An Emerging Target in Therapeutics

Elabela, a bioactive micropeptide, is recognized as the second endogenous ligand for the Apelin receptor and is widely distributed in different tissues and organs. Elabela plays an important role in various physiological processes, such as blood pressure control, heart morphogenesis, apoptosis, angiogenesis, cell proliferation, migration, etc. Elabela is also implicated in pathological conditions, like cardiac dysfunctions, heart failure, hypertension, kidney diseases, cancer and CNS disorders. The association of Elabela with these disease conditions makes it a potential target for their therapy. This review summarizes the physiological role of Elabela peptide as well as its implication in various disease conditions.

Differentially CTCF-Binding Sites in Cattle Rumen Tissue during Weaning

The weaning transition in calves is characterized by major structural changes such as an increase in the rumen capacity and surface area due to diet changes. Studies evaluating rumen development in calves are vital to identify genetic mechanisms affected by weaning. This study aimed to provide a genome-wide characterization of CTCF-binding sites and differentially CTCF-binding sites (DCBS) in rumen tissue during the weaning transition of four Holstein calves to uncover regulatory elements in rumen epithelial tissue using ChIP-seq. Our study generated 67,280 CTCF peaks for the before weaning (BW) and 39,891 for after weaning (AW). Then, 7401 DCBS were identified for the AW vs. BW comparison representing 0.15% of the cattle genome, comprising ~54% of induced DCBS and ~46% of repressed DCBS. Most of the induced and repressed DCBS were in distal intergenic regions, showing a potential role as insulators. Gene ontology enrichment revealed many shared GO terms for the induced and the repressed DCBS, mainly related to cellular migration, proliferation, growth, differentiation, cellular adhesion, digestive tract morphogenesis, and response to TGFβ. In addition, shared KEGG pathways were obtained for adherens junction and focal adhesion. Interestingly, other relevant KEGG pathways were observed for the induced DCBS like gastric acid secretion, salivary secretion, bacterial invasion of epithelial cells, apelin signaling, and mucin-type O-glycan biosynthesis. IPA analysis further revealed pathways with potential roles in rumen development during weaning, including TGFβ, Integrin-linked kinase, and Integrin signaling. When DCBS were further integrated with RNA-seq data, 36 putative target genes were identified for the repressed DCBS, including KRT84, COL9A2, MATN3, TSPAN1, and AJM1. This study successfully identified DCBS in cattle rumen tissue after weaning on a genome-wide scale and revealed several candidate target genes that may have a role in rumen development, such as TGFβ, integrins, keratins, and SMADs. The information generated in this preliminary study provides new insights into bovine genome regulation and chromatin landscape.

Renal water transport in health and disease

Saving body water by optimal reabsorption of water filtered by the kidney leading to excretion of urine with concentrations of solutes largely above that of plasma allowed vertebrate species to leave the aquatic environment to live on solid ground. Filtered water is reabsorbed for 70% and 20% by proximal tubules and thin descending limbs of Henle, respectively. These two nephron segments express the water channel aquaporin-1 located along both apical and basolateral membranes. In the proximal tubule, the paracellular pathway accounts for at least 30% of water reabsorption, and the tight-junction core protein claudin-2 plays a key role in this permeability. The ascending limb of Henle and the distal convoluted tubule are impermeant to water and are responsible for urine dilution. The water balance is adjusted along the collecting system, i.e. connecting tubule and the collecting duct, under the control of arginine-vasopressin (AVP). AVP is synthesized by the hypothalamus and released in response to an increase in extracellular osmolality or stimulation of baroreceptors by decreased blood pressure. In response to AVP, aquaporin-2 water channels stored in subapical intracellular vesicles are translocated to the apical plasma membrane and raise the water permeability of the collecting system. The basolateral step of water reabsorption is mediated by aquaporin-3 and -4, which are constitutively expressed. Drugs targeting water transport include classical diuretics, which primarily inhibit sodium transport; the new class of SGLT2 inhibitors, which promotes osmotic diuresis and the non-peptidic antagonists of the V2 receptor, which are pure aquaretic drugs. Disturbed water balance includes diabetes insipidus and hyponatremias. Diabetes insipidus is characterized by polyuria and polydipsia. It is either related to a deficit in AVP secretion called central diabetes insipidus that can be treated by AVP analogs or to a peripheral defect in AVP response called nephrogenic diabetes insipidus. Diabetes insipidus can be either of genetic origin or acquired. Hyponatremia is a common disorder most often related to free water excess relying on overstimulated or inappropriate AVP secretion. The assessment of blood volume is key for the diagnosis and treatment of hyponatremia, which can be classified as hypo-, eu-, or hypervolemic.

The Effect of SGLT2 Inhibitor Dapagliflozin on Serum Levels of Apelin in T2DM Patients with Heart Failure

Apelin is a multifunctional peptide that plays a pivotal role in cardiac remodeling and HF manifestation because of counteracting angiotensin-II. We hypothesized that positive influence of sodium-glucose co-transporter-2 (SGLT2) inhibitor on cardiac function in T2DM patients with HF might be mediated by apelin and that its levels seem to be a target of management. A total of 153 type 2 diabetes mellitus (T2DM) patients with II/III HF NYHA class and average left ventricular (LV) ejection fraction (EF) of 46% have been enrolled and treated with dapagliflosin. The serum levels of apelin and N-terminal brain natriuretic pro-peptide (NT-proBNP) were measured at baseline and over a 6-month period of dapagliflosin administration. We noticed that administration of dapagliflozin was associated with a significant increase in apelin levels of up to 18.3% and a decrease in NT-proBNP of up to 41.0%. Multivariate logistic regression showed that relative changes of LVEF, LA volume index, and early diastolic blood filling to longitudinal strain ratio were strongly associated with the levels of apelin, whereas NT-proBNP exhibited a borderline significance in this matter. In conclusion, dapagiflosin exerted a positive impact on echocardiographic parameters in close association with an increase in serum apelin levels, which could be a surrogate target for HF management.

Fusion of Normoxic- and Hypoxic-Preconditioned Myoblasts Leads to Increased Hypertrophy

Injuries, high altitude, and endurance exercise lead to hypoxic conditions in skeletal muscle and sometimes to hypoxia-induced local tissue damage. Thus, regenerative myoblasts/satellite cells are exposed to different levels and durations of partial oxygen pressure depending on the spatial distance from the blood vessels. To date, it is unclear how hypoxia affects myoblasts proliferation, differentiation, and particularly fusion with normoxic myoblasts. To study this, we investigated how 21% and 2% oxygen affects C2C12 myoblast morphology, proliferation, and myogenic differentiation and evaluated the fusion of normoxic- or hypoxic-preconditioned C2C12 cells in 21% or 2% oxygen in vitro. Out data show that the long-term hypoxic culture condition does not affect the proliferation of C2C12 cells but leads to rounder cells and reduced myotube formation when compared with myoblasts exposed to normoxia. However, when normoxic- and hypoxic-preconditioned myoblasts were differentiated together, the resultant myotubes were significantly larger than the control myotubes. Whole transcriptome sequencing analysis revealed several novel candidate genes that are differentially regulated during the differentiation under normoxia and hypoxia in mixed culture conditions and may thus be involved in the increase in myotube size. Taken together, oxygen-dependent adaption and interaction of myoblasts may represent a novel approach for the development of innovative therapeutic targets.

Discriminative Utility of Apelin-to-NT-Pro-Brain Natriuretic Peptide Ratio for Heart Failure with Preserved Ejection Fraction among Type 2 Diabetes Mellitus Patients

BACKGROUND

Apelin is a regulatory vasoactive peptide, which plays a pivotal role in adverse cardiac remodeling and heart failure (HF) with reduced ejection fraction. The purpose of the study was to investigate whether serum levels of apelin is associated with HF with preserved election fraction (HFpEF) in patients with T2DM.

METHODS

The study retrospectively involved 101 T2DM patients aged 41 to 62 years (48 patients with HFpEF and 28 non-HFpEF patients). The healthy control group consisted of 25 individuals with matched age and sex. Data collection included demographic and anthropometric information, hemodynamic performances and biomarkers of the disease. Transthoracic B-mode echocardiography, Doppler and TDI were performed at baseline. Serum levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) and apelin were measured by ELISA in all patients at the study entry.

RESULTS

Unadjusted multivariate logistic model yielded the only apelin to NT-proBNP ratio (OR = 1.44; p = 0.001), BMI > 34 кг/м2 (OR = 1.07; p = 0.036), NT-proBNP > 458 pmol/mL (OR = 1.17; p = 0.042), LAVI > 34 mL/m2 (OR = 1.06; p = 0.042) and E/e' > 11 (OR = 1.04; p = 0.044) remained to be strong predictors for HFpEF. After obesity adjustment, multivariate logistic regression showed that the apelin to NT-proBNP ratio < 0.82 × 10-2 units remained sole independent predictor for HFpEF (OR = 1.44; 95% CI: 1.18-2.77; p = 0.001) HFpEF in T2DM patients. In conclusion, we found that apelin to NT-proBNP ratio < 0.82 × 10-2 units better predicted HFpEF in T2DM patients than apelin and NT-proBNP alone. This finding could open new approach for CV risk stratification of T2DM at higher risk of HF.