The chromogranins A and B: the first 25 years and future perspectives

Molecular classification and tumor microenvironment characteristics in pheochromocytomas

Pheochromocytomas (PCCs) are rare neuroendocrine tumors that originate from chromaffin cells in the adrenal gland. However, the cellular molecular characteristics and immune microenvironment of PCCs are incompletely understood. Here, we performed single-cell RNA sequencing (scRNA-seq) on 16 tissues from 4 sporadic unclassified PCC patients and 1 hereditary PCC patient with Von Hippel-Lindau (VHL) syndrome. We found that intra-tumoral heterogeneity was less extensive than the inter-individual heterogeneity of PCCs. Further, the unclassified PCC patients were divided into two types, metabolism-type (marked by NDUFA4L2 and COX4I2) and kinase-type (marked by RET and PNMT), validated by immunohistochemical staining. Trajectory analysis of tumor evolution revealed that metabolism-type PCC cells display phenotype of consistently active metabolism and increased metastasis potential, while kinase-type PCC cells showed decreased epinephrine synthesis and neuron-like phenotypes. Cell-cell communication analysis showed activation of the annexin pathway and a strong inflammation reaction in metabolism-type PCCs and activation of FGF signaling in the kinase-type PCC. Although multispectral immunofluorescence staining showed a lack of CD8+ T cell infiltration in both metabolism-type and kinase-type PCCs, only the kinase-type PCC exhibited downregulation of HLA-I molecules that possibly regulated by RET, suggesting the potential of combined therapy with kinase inhibitors and immunotherapy for kinase-type PCCs; in contrast, the application of immunotherapy to metabolism-type PCCs (with antigen presentation ability) is likely unsuitable. Our study presents a single-cell transcriptomics-based molecular classification and microenvironment characterization of PCCs, providing clues for potential therapeutic strategies to treat PCCs.

Chromogranin A and its derived peptides: potential regulators of cholesterol homeostasis

Chromogranin A (CHGA), a member of the granin family of proteins, has been an attractive therapeutic target and candidate biomarker for several cardiovascular, neurological, and inflammatory disorders. The prominence of CHGA stems from the pleiotropic roles of several bioactive peptides (e.g., catestatin, pancreastatin, vasostatins) generated by its proteolytic cleavage and by their wide anatomical distribution. These peptides are emerging as novel modulators of cardiometabolic diseases that are often linked to high blood cholesterol levels. However, their impact on cholesterol homeostasis is poorly understood. The dynamic nature of cholesterol and its multitudinous roles in almost every aspect of normal body function makes it an integral component of metabolic physiology. A tightly regulated coordination of cholesterol homeostasis is imperative for proper functioning of cellular and metabolic processes. The deregulation of cholesterol levels can result in several pathophysiological states. Although studies till date suggest regulatory roles for CHGA and its derived peptides on cholesterol levels, the mechanisms by which this is achieved still remain unclear. This review aims to aggregate and consolidate the available evidence linking CHGA with cholesterol homeostasis in health and disease. In addition, we also look at common molecular regulatory factors (viz., transcription factors and microRNAs) which could govern the expression of CHGA and genes involved in cholesterol homeostasis under basal and pathological conditions. In order to gain further insights into the pathways mediating cholesterol regulation by CHGA/its derived peptides, a few prospective signaling pathways are explored, which could act as primers for future studies.

Catestatin: Antimicrobial Functions and Potential Therapeutics

The rapid increase in drug-resistant and multidrug-resistant infections poses a serious challenge to antimicrobial therapies, and has created a global health crisis. Since antimicrobial peptides (AMPs) have escaped bacterial resistance throughout evolution, AMPs are a category of potential alternatives for antibiotic-resistant "superbugs". The Chromogranin A (CgA)-derived peptide Catestatin (CST: hCgA352-372; bCgA344-364) was initially identified in 1997 as an acute nicotinic-cholinergic antagonist. Subsequently, CST was established as a pleiotropic hormone. In 2005, it was reported that N-terminal 15 amino acids of bovine CST (bCST1-15 aka cateslytin) exert antibacterial, antifungal, and antiyeast effects without showing any hemolytic effects. In 2017, D-bCST1-15 (where L-amino acids were changed to D-amino acids) was shown to exert very effective antimicrobial effects against various bacterial strains. Beyond antimicrobial effects, D-bCST1-15 potentiated (additive/synergistic) antibacterial effects of cefotaxime, amoxicillin, and methicillin. Furthermore, D-bCST1-15 neither triggered bacterial resistance nor elicited cytokine release. The present review will highlight the antimicrobial effects of CST, bCST1-15 (aka cateslytin), D-bCST1-15, and human variants of CST (Gly364Ser-CST and Pro370Leu-CST); evolutionary conservation of CST in mammals; and their potential as a therapy for antibiotic-resistant "superbugs".

The Effect of Biological Treatment on Stress Parameters Determined in Saliva in Patients with Severe Psoriasis

Background and objectives: In psoriatic patients, stress is the most common aggravating factor. Despite the use of quality-of-life assessment questionnaires, diagnosing stress in psoriatic patients is not a flawless procedure. This study aimed to assess the usefulness of potential stress biomarkers in saliva for monitoring the treatment of psoriasis. Materials and methods: A total of 104 adult patients with severe psoriasis were included and randomly treated via biological treatment or symptomatic therapy: 84 received biological treatment, with 20 formed a control group receiving symptomatic therapy. The administered biological treatment was adalimumab, whilst in controls calcipotriol/betamethasone dipropionate topical gel and emollients were used. Patients were monitored monthly with a dermatological examination and the dispensing of a biological drug. During each of the four visits, the severity of the disease was assessed (PASI, BSA, and DLQI), and a sample of the patient’s saliva was taken. In all the participants, the saliva concentrations of immunoglobulin A (sIgA), α-amylase (sAA), and chromogranin A (CgA) were measured. Results: The majority of patients in both the study and control groups achieved clinical improvement, though favoring the group receiving biological treatment. The concentration of sIgA in the saliva was constantly increasing in the study group during subsequent visits (Fr = 27.26; p < 0.001). Meanwhile, there were no statistically significant changes in the control group during the same follow-up period (Fr = 6.66; p = 0.084). Levels of sAA underwent statistically significant changes in both groups (Fr = 58.02; p < 0.001—study group and Fr = 13.74; p = 0.003—control group). In the study group, a steady, statistically significant increase in sAA was observed from the first to the third visit. In the study group, a downward trend in CgA concentration was observed. In the control group, no significant differences in the level of CgA were obtained. Conclusions: sIgA, sAA, and CgA are potential markers of the severity of psoriasis and the associated stress reaction. Based on the presented observations, only sIgA and CgA seem to be valuable biomarkers for monitoring the effectiveness of the systemic treatment of psoriasis.

Forty years of the adrenal chromaffin cell through ISCCB meetings around the world

This historical review focuses on the evolution of the knowledge accumulated during the last two centuries on the biology of the adrenal medulla gland and its chromaffin cells (CCs). The review emerged in the context of a series of meetings that started on the Spanish island of Ibiza in 1982 with the name of the International Symposium on Chromaffin Cell Biology (ISCCB). Hence, the review is divided into two periods namely, before 1982 and from this year to 2022, when the 21st ISCCB meeting was just held in Hamburg, Germany. The first historical period extends back to 1852 when Albert Kölliker first described the fine structure and function of the adrenal medulla. Subsequently, the adrenal staining with chromate salts identified the CCs; this was followed by the establishment of the embryological origin of the adrenal medulla, and the identification of adrenaline-storing vesicles. By the end of the nineteenth century, the basic morphology, histochemistry, and embryology of the adrenal gland were known. The twentieth century began with breakthrough findings namely, the experiment of Elliott suggesting that adrenaline was the sympathetic neurotransmitter, the isolation of pure adrenaline, and the deciphering of its molecular structure and chemical synthesis in the laboratory. In the 1950s, Blaschko isolated the catecholamine-storing vesicles from adrenal medullary extracts. This switched the interest in CCs as models of sympathetic neurons with an explosion of studies concerning their functions, i.e., uptake of catecholamines by chromaffin vesicles through a specific coupled transport system; the identification of several vesicle components in addition to catecholamines including chromogranins, ATP, opioids, and other neuropeptides; the calcium-dependence of the release of catecholamines; the underlying mechanism of exocytosis of this release, as indicated by the co-release of proteins; the cross-talk between the adrenal cortex and the medulla; and the emission of neurite-like processes by CCs in culture, among other numerous findings. The 1980s began with the introduction of new high-resolution techniques such as patch-clamp, calcium probes, marine toxins-targeting ion channels and receptors, confocal microscopy, or amperometry. In this frame of technological advances at the Ibiza ISCCB meeting in 1982, 11 senior researchers in the field predicted a notable increase in our knowledge in the field of CCs and the adrenal medulla; this cumulative knowledge that occurred in the last 40 years of history of the CC is succinctly described in the second part of this historical review. It deals with cell excitability, ion channel currents, the exocytotic fusion pore, the handling of calcium ions by CCs, the kinetics of exocytosis and endocytosis, the exocytotic machinery, and the life cycle of secretory vesicles. These concepts together with studies on the dynamics of membrane fusion with super-resolution imaging techniques at the single-protein level were extensively reviewed by top scientists in the field at the 21st ISCCB meeting in Hamburg in the summer of 2022; this frontier topic is also briefly reviewed here. Many of the concepts arising from those studies contributed to our present understanding of synaptic transmission. This has been studied in physiological or pathophysiological conditions, in CCs from animal disease models. In conclusion, the lessons we have learned from CC biology as a peripheral model for brain and brain disease pertain more than ever to cutting-edge research in neurobiology. In the 22nd ISCCB meeting in Israel in 2024 that Uri Asheri is organizing, we will have the opportunity of seeing the progress of the questions posed in Ibiza, and on other questions that undoubtedly will arise.

The immunomodulatory functions of chromogranin A-derived peptide pancreastatin

Chromogranin A (CgA) is a 439 amino acid protein secreted by neuroendocrine cells. Proteolytic processing of CgA results in the production of different bioactive peptides. These peptides have been associated with inflammatory bowel disease, diabetes, and cancer. One of the chromogranin A-derived peptides is ∼52 amino acid long Pancreastatin (PST: human (h)CgA250-301, murine (m)CgA263-314). PST is a glycogenolytic peptide that inhibits glucose-induced insulin secretion from pancreatic islet β-cells. In addition to this metabolic role, evidence is emerging that PST also has inflammatory properties. This review will discuss the immunomodulatory properties of PST and its possible mechanisms of action and regulation. Moreover, this review will discuss the potential translation to humans and how PST may be an interesting therapeutic target for treating inflammatory diseases.

Circulating Neuroendocrine Tumor Biomarkers: Past, Present and Future

Neuroendocrine tumors are a heterogeneous group of neoplasms originating from the diffuse endocrine system. Depending on primary location and hormonal status, they range in terms of clinical presentation, prognosis and treatment. Functional tumors often develop symptoms indicating an excess of hormones produced by the neoplasm (exempli gratia insulinoma, glucagonoma and VIPoma) and can be diagnosed using monoanalytes. For non-functional tumors (inactive or producing insignificant amounts of hormones), universal biomarkers have not been established. The matter remains an important unmet need in the field of neuroendocrine tumors. Substances researched over the years, such as chromogranin A and neuron-specific enolase, lack the desired sensitivity and specificity. In recent years, the potential use of Circulating Tumor Cells or multianalytes such as a circulating microRNA and NETest have been widely discussed. They offer superior diagnostic parameters in comparison to traditional biomarkers and depict disease status in a more comprehensive way. Despite a lot of promise, no international standards have yet been developed regarding their routine use and clinical application. In this literature review, we describe the analytes used over the years and cover novel biomarkers that could find a use in the future. We discuss their pros and cons while showcasing recent advances in the field of neuroendocrine tumor biomarkers.

Catestatin induces glycogenesis by stimulating the phosphoinositide 3-kinase-AKT pathway

AIM

Defects in hepatic glycogen synthesis contribute to post-prandial hyperglycaemia in type 2 diabetic patients. Chromogranin A (CgA) peptide Catestatin (CST: hCgA352-372 ) improves glucose tolerance in insulin-resistant mice. Here, we seek to determine whether CST induces hepatic glycogen synthesis.

METHODS

We determined liver glycogen, glucose-6-phosphate (G6P), uridine diphosphate glucose (UDPG) and glycogen synthase (GYS2) activities; plasma insulin, glucagon, noradrenaline and adrenaline levels in wild-type (WT) as well as in CST knockout (CST-KO) mice; glycogen synthesis and glycogenolysis in primary hepatocytes. We also analysed phosphorylation signals of insulin receptor (IR), insulin receptor substrate-1 (IRS-1), phosphatidylinositol-dependent kinase-1 (PDK-1), GYS2, glycogen synthase kinase-3β (GSK-3β), AKT (a kinase in AKR mouse that produces Thymoma)/PKB (protein kinase B) and mammalian/mechanistic target of rapamycin (mTOR) by immunoblotting.

RESULTS

CST stimulated glycogen accumulation in fed and fasted liver and in primary hepatocytes. CST reduced plasma noradrenaline and adrenaline levels. CST also directly stimulated glycogenesis and inhibited noradrenaline and adrenaline-induced glycogenolysis in hepatocytes. In addition, CST elevated the levels of UDPG and increased GYS2 activity. CST-KO mice had decreased liver glycogen that was restored by treatment with CST, reinforcing the crucial role of CST in hepatic glycogenesis. CST improved insulin signals downstream of IR and IRS-1 by enhancing phospho-AKT signals through the stimulation of PDK-1 and mTORC2 (mTOR Complex 2, rapamycin-insensitive complex) activities.

CONCLUSIONS

CST directly promotes the glycogenic pathway by (a) reducing glucose production, (b) increasing glycogen synthesis from UDPG, (c) reducing glycogenolysis and (d) enhancing downstream insulin signalling.

Serpinin in the Skin

The serpinins are relatively novel peptides generated by proteolytic processing of chromogranin A and they are comprised of free serpinin, serpinin-RRG and pGlu-serpinin. In this study, the presence and source of these peptides were studied in the skin. By Western blot analysis, a 40 kDa and a 50 kDa protein containing the sequence of serpinin were detected in the trigeminal ganglion and dorsal root ganglia in rats but none in the skin. RP-HPLC followed by EIA revealed that the three serpinins are present in similar, moderate amounts in rat dorsal root ganglia, whereas in the rat skin, free serpinin represents the predominant molecular form. There were abundant serpinin-positive cells in rat dorsal root ganglia and colocalization with substance P was evident. However, much more widespread distribution of the serpinins was found in dorsal root ganglia when compared with substance P. In the skin, serpinin immunoreactivity was found in sensory nerves and showed colocalization with substance P; as well, some was present in autonomic nerves. Thus, although not exclusively, there is evidence that serpinin is a constituent of the sensory innervation of the skin. The serpinins are biologically highly active and might therefore be of functional significance in the skin.

Use of saliva stress biomarkers to estimate novice male endoscopist's stress during training in a high-end simulator

OBJECTIVE

Simulated endoscopic training can be challenging and stressful for the novice trainee. The absence of a reliable stress detection method during simulated endoscopic training makes estimating trainees' mental stress difficult to quantify. This study concomitantly measures the responses of four saliva stress biomarkers and compares them to the video score (VS) achieved by novice endoscopists in a reproducibly stressful simulation environment.

METHODS

Thirty-six male endoscopy naïve surgery residents were enrolled. After an orientation phase, a saliva specimen was collected for cortisol (sC), alpha-amylase (sAA), Chromogranin A (sCgA), and immunoglobulin A (sIgA) measurements (baseline phase, BL). Thereafter, the simulation exercise phase (E) started, practicing in the Fundamentals of Endoscopic Surgery Skills module (GI-Bronch Mentor). Immediately after, a second saliva sample for measuring the above-cited biomarkers was collected. The whole experiment was videotaped, and the VS was calculated. The percentage (E-BL)_diff of each of the four saliva biomarkers was calculated and examined for correlation to VS.

RESULTS

sCgA_diff showed the best correlation with VS, followed by sAA_diff.

CONCLUSIONS

sCgA and sAA, are saliva stress biomarkers that are easy to collect non-invasively and showed the best correlation with novice endoscopist's performance in our simulation setting, and therefore, they could be used for monitoring stress.

The goldfish Carassius auratus: an emerging animal model for comparative cardiac research

The use of unconventional model organisms is significantly increasing in different fields of research, widely contributing to advance life sciences understanding. Among fishes, the cyprinid Carassius auratus (goldfish) is largely used for studies on comparative and evolutionary endocrinology, neurobiology, adaptive and conservation physiology, as well as for translational research aimed to explore mechanisms that may be useful in an applicative biomedical context. More recently, the research possibilities offered by the goldfish are further expanded to cardiac studies. A growing literature is available to illustrate the complex networks involved in the modulation of the goldfish cardiac performance, also in relation to the influence of environmental signals. However, an overview on the existing current knowledge is not yet available. By discussing the mechanisms that in C. auratus finely regulate the cardiac function under basal conditions and under environmental challenges, this review highlights the remarkable flexibility of the goldfish heart in relation not only to the basic morpho-functional design and complex neuro-humoral traits, but also to its extraordinary biochemical-metabolic plasticity and its adaptive potential. The purpose of this review is also to emphasize the power of the heart of C. auratus as an experimental tool useful to investigate mechanisms that could be difficult to explore using more conventional animal models and complex cardiac designs.

Role and function of granin proteins in diabetes mellitus

The granin glycoprotein family consists of nine acidic proteins; chromogranin A (CgA), chromogranin B (CgB), and secretogranin II–VIII. They are produced by a wide range of neuronal, neuroendocrine, and endocrine cells throughout the human body. Their major intracellular function is to sort peptides and proteins into secretory granules, but their cleavage products also take part in the extracellular regulation of diverse biological processes. The contribution of granins to carbohydrate metabolism and diabetes mellitus is a recent research area. CgA is associated with glucose homeostasis and the progression of type 1 diabetes. WE-14, CgA_10-19, and CgA_43-52 are peptide derivates of CgA, and act as CD4⁺ or CD8⁺ autoantigens in type 1 diabetes, whereas pancreastatin (PST) and catestatin have regulatory effects in carbohydrate metabolism. Furthermore, PST is related to gestational and type 2 diabetes. CgB has a crucial role in physiological insulin secretion. Secretogranins II and III have angiogenic activity in diabetic retinopathy (DR), and are novel targets in recent DR studies. Ongoing studies are beginning to investigate the potential use of granin derivatives as drugs to treat diabetes based on the divergent relationships between granins and different types of diabetes.

Use of Chromogranin A for Monitoring Patients With Pancreatic Neuroendocrine Neoplasms

OBJECTIVE

We aimed to assess the role of serum chromogranin A (CgA) in monitoring disease status and treatment response in patients with pancreatic neuroendocrine neoplasms (pNENs).

METHODS

We included posttherapy pNENs patients with measured serum CgA levels who underwent 68Ga-labeled tetraazacyclododecanetetraacetic acid-peptide positron emission tomography (PET) imaging between April 2017 and January 2020. Serum CgA levels were determined by enzyme-linked immunosorbent assay. Tumor response was assessed according to the PET response evaluation criteria in solid tumors.

RESULTS

Seventy-seven patients with 101 events were included in this study. Serum CgA levels were significantly higher in patients with active disease and metastasis. The optimal cutoff values for CgA for active and metastatic pNENs diagnosis after treatment were 52.39 (77.8% sensitivity, 80.7% specificity) and 60.18 ng/mL (73.9% sensitivity, 73.1% specificity), respectively. Based on 18 patients with serial CgA measurements and PET imaging, the optimal changes in CgA levels for predicting disease remission and progression were a 28.5% decrease (71.4% sensitivity, 88.2% specificity) and a 21.0% increase (100.0% sensitivity, 75.0% specificity), respectively.

CONCLUSIONS

We concluded that serum CgA levels are associated with disease status and treatment response and may thus provide a helpful biomarker for the monitoring and clinical management of patients with pNENs.

Chromogranin A regulates gut permeability via the antagonistic actions of its proteolytic peptides

AIM

A "leaky" gut barrier has been implicated in the initiation and progression of a multitude of diseases, for example, inflammatory bowel disease (IBD), irritable bowel syndrome and celiac disease. Here we show how pro-hormone Chromogranin A (CgA), produced by the enteroendocrine cells, and Catestatin (CST: hCgA_352-372 ), the most abundant CgA-derived proteolytic peptide, affect the gut barrier.

METHODS

Colon tissues from region-specific CST-knockout (CST-KO) mice, CgA-knockout (CgA-KO) and WT mice were analysed by immunohistochemistry, western blot, ultrastructural and flowcytometry studies. FITC-dextran assays were used to measure intestinal barrier function. Mice were supplemented with CST or CgA fragment pancreastatin (PST: CgA_250-301 ). The microbial composition of cecum was determined. CgA and CST levels were measured in blood of IBD patients.

RESULTS

Plasma levels of CST were elevated in IBD patients. CST-KO mice displayed (a) elongated tight, adherens junctions and desmosomes similar to IBD patients, (b) elevated expression of Claudin 2, and (c) gut inflammation. Plasma FITC-dextran measurements showed increased intestinal paracellular permeability in the CST-KO mice. This correlated with a higher ratio of Firmicutes to Bacteroidetes, a dysbiotic pattern commonly encountered in various diseases. Supplementation of CST-KO mice with recombinant CST restored paracellular permeability and reversed inflammation, whereas CgA-KO mice supplementation with CST and/or PST in CgA-KO mice showed that intestinal paracellular permeability is regulated by the antagonistic roles of these two peptides: CST reduces and PST increases permeability.

CONCLUSION

The pro-hormone CgA regulates the intestinal paracellular permeability. CST is both necessary and sufficient to reduce permeability and primarily acts by antagonizing PST.

A novel bioengineered fragment peptide of Vasostatin-1 exerts smooth muscle pharmacological activities and anti-angiogenic effects via blocking VEGFR signalling pathway

Chromogranin A (CgA) is a hydrophilic glycoprotein released by post-ganglionic sympathetic neurons. CgA consists of a single peptide chain containing numerous paired basic residues, which are typical cleavage sites in prohormones to generate bioactive peptides. It is recognized as a diagnostic and prognostic serum marker for neuroendocrine tumours. Vasostatin-1 is one of the most conserved regions of CgA and has diverse inhibitory biological activities. In this study, a novel peptide fragment that contains three typical functional structures of Vasostatin-1 was synthesized. This unique bioengineered Vasostatin-1 Derived Peptide (named V1DP) includes a highly conserved domain between vertebrate species in its N-terminal region, comprising a disulphide bridge formed by two cysteine residues at amino acid positions 17 and 38, respectively. Besides, V1DP contains two significant tripeptide recognition sequences: the amino acid triplets, RGD and KGD. Our data demonstrated that V1DP could induce a dose-dependent relaxation of rat arterial smooth muscle and also increase the contraction activity of rat uterus smooth muscle. More importantly, we found that V1DP inhibits cancer cell proliferation, modulate the HUVEC cell migration, and exhibit anti-angiogenesis effect both in vitro and in vivo. We further investigated the actual mechanism of V1DP, and our results confirmed that V1DP involves inhibiting the vascular endothelial growth factor receptor (VEGFR) signalling. We docked V1DP to the apo structures of VEGFR2 and examined the stability of the peptide in the protein pockets. Our simulation and free energy calculations results indicated that V1DP can bind to the catalytic domain and regulatory domain pockets, depending on whether the conformational state of the protein is JM-in or JM-out. Taken together, our data suggested that V1DP plays a role as the regulator of endothelial cell function and smooth muscle pharmacological homeostasis. V1DP is a water-soluble and biologically stable peptide and could further develop as an anti-angiogenic drug for cancer treatment.

Immunosuppression of Macrophages Underlies the Cardioprotective Effects of CST (Catestatin)

[Figure: see text].

Histopathological Chromogranin A-Positivity Is Associated with Right-Sided Colorectal Cancers and Worse Prognosis

Simple Summary

Several factors are known to affect colorectal cancer (CRC) patient survival, including elevated platelet counts (thrombocytosis) and chromogranin A-positive neuroendocrine-cell differentiation (CgA⁺). Thrombocytosis can occur due to biochemical changes caused by the tumor itself (known as paraneoplastic thrombocytosis) or due to the bleeding of the tumor (reactive thrombocytosis). Our effort was primarily focused on (1) determining if CgA⁺ and paraneoplastic thrombocytosis combined can affect CRC and (2) finding out if there is a possible connection between the two. With the help of chromogranin A immunohistochemical staining, the measurement of circulating biochemical markers of paraneoplastic thrombocytosis (interleukin-6 and thrombopoietin) and chromogranins A and -B, indication was found that CRC combined with CgA⁺ has a well-distinguishable pathophysiology, compared to CRCs without CgA⁺. A possible, new subtype of CRC is proposed, which can be identified easily with chromogranin A immunohistochemical staining. However, its impact should be further studied.

Abstract

Background: Colorectal cancer (CRC) is known to be affected by paraneoplastic thrombocytosis and chromogranin A-positive neuroendocrine-cell differentiation (CgA⁺). Their combined effect has never been previously investigated. Methods: A prospective cohort pilot study of 42 CRC patients and 42 age- and sex-matched controls was carried out. Plasma interleukin-6, thrombopoietin, and serum chromogranin A and -B were measured; furthermore, tumor tissue was immunohistochemically stained for CgA⁺. Results: Twenty-seven and 15 patients were assigned to the chromogranin A-negative (CgA⁻) and CgA⁺ groups, respectively. Within the CgA⁺ group, right-sided tumors were more frequent (18.5% vs. 53.3%), no stage I cancer was found, and patients of this group were in worse general condition. Compared to control subjects, chromogranin A level was higher in the CgA⁺ group (p = 0.0086), thrombopoietin (p = 0.0040) and chromogranin B (p = 0.0070) in the CgA⁻ group, while interleukin-6 was high in both tumor groups (p ≤ 0.0090). Survival was significantly worse in the CgA⁺ group (hazard ratio: 5.73; p = 0.0378). Conclusions: Different thrombopoietin levels indicated distinct thrombocytosis types. Within the two CRC groups, serum levels of chromogranins changed in different directions suggesting two well-distinguishable pathophysiologies. Based on these observations we propose a new subtype of CRC, which can be characterized by chromogranin A-positive neuroendocrine-cell differentiation.

Catestatin peptide of chromogranin A as a potential new target for several risk factors management in the course of metabolic syndrome

Obesity, lipodystrophy, diabetes, and hypertension collectively constitute the main features of Metabolic Syndrome (MetS), together with insulin resistance (IR), which is considered as a defining element. MetS generally leads to the development of cardiovascular disease (CVD), which is a determinant cause of mortality and morbidity in humans and animals. Therefore, it is essential to implement and put in place adequate management strategies for the treatment of this disease. Catestatin is a bioactive peptide with 21 amino acids, which is derived through cleaving of the prohormone chromogranin A (CHGA/CgA) that is co-released with catecholamines from secretory vesicles and, which is responsible for hepatic/plasma lipids and insulin levels regulation, improves insulin sensitivity, reduces hypertension and attenuates obesity in murine models. In humans, there were few published studies, which showed that low levels of catestatin are significant risk factors for hypertension in adult patients. These accumulating evidence documents clearly that catestatin peptide (CST) is linked to inflammatory and metabolic syndrome diseases and can be a novel regulator of insulin and lipid levels, blood pressure, and cardiac function. The goal of this review is to provide an overview of the CST effects in metabolic syndrome given its role in metabolic regulation and thus, provide new insights into the use of CST as a diagnostic marker and therapeutic target.

Carbon-Fiber Nanoelectrodes for Real-Time Discrimination of Vesicle Cargo in the Native Cellular Environment

Carbon-fiber microelectrodes have proven to be an indispensable tool for monitoring exocytosis events using amperometry. When positioned adjacent to a cell, a traditional microdisc electrode is well suited for quantification of discrete exocytotic release events. However, the size of the electrode does not allow for intracellular electrochemical measurements, and the amperometric approach cannot distinguish between the catecholamines that are released. In this work, carbon nanoelectrodes were developed to permit selective electrochemical sampling of nanoscale vesicles in the cell cytosol. Classical voltammetric techniques and electron microscopy were used to characterize the nanoelectrodes, which were ∼5 μm long and sharpened to a nanometer-scale tip that could be wholly inserted into individual neuroendocrine cells. The nanoelectrodes were coupled with fast-scan cyclic voltammetry to distinguish secretory granules containing epinephrine from other catecholamine-containing granules encountered in the native cellular environment. Both vesicle subtypes were encountered in most cells, despite prior demonstration of populations of chromaffin cells that preferentially release one of these catecholamines. There was substantial cell-to-cell variability in relative epinephrine content, and vesicles containing epinephrine generally stored more catecholamine than the other vesicles. The carbon nanoelectrode technology thus enabled analysis of picoliter-scale biological volumes, revealing key differences between chromaffin cells at the level of the dense-core granule.

Endocrinological effect of lavender aromatherapy on stressful visual stimuli

Introduction

Aromatherapy is prominent in complementary and alternative medicine. Little endocrinological evidence, however, of the effects of aromatherapy has yet been presented. We used salivary stress marker chromogranin A (CgA) to examine the effects of lavender aroma on women watching a stressful video.

Methods

Healthy female university students (n = 23) aged 20-22 years old were randomly assigned to two groups: an aroma group exposed to lavender and an unexposed control group. Both groups watched a stressful video for 10 min. During the protocol, the aroma group was exposed to lavender aroma. Samples of salivary chromogranin A (CgA) were collected immediately before and after watching the video, and at 5 and 10 min after that.

Results

In the aroma group, the levels of CgA statistically significantly decreased throughout the experimental period. In the control group, there was no such change.

Conclusion

The findings suggest that lavender aroma may reduce the stress effects of watching a stressful video.

Neuroendocrine Targeting of Tissue Plasminogen Activator (t-PA)

t-PA has a widespread neuroendocrine distribution including prominent expression in chromaffin cells of the sympathoadrenal system. Chromaffin cell t-PA is sorted into catecholamine storage vesicles and co-released with catecholamines in response to sympathoadrenal activation, suggesting that catecholamine storage vesicles may serve as a reservoir for the rapid release of t-PA. Chromogranin A (CgA), a major core protein in secretory vesicles throughout the neuroendocrine system, may play a crucial role in targeting proteins into the regulated secretory pathway, by forming aggregated "granin" complexes to which other proteins destined for the regulated secretory vesicle bind and become separated from constitutively secreted proteins in the trans-Golgi network (TGN). Formation of such complexes is facilitated by conditions of the TGN (low pH, high Ca⁺²). We tested the hypothesis that t-PA interacts specifically with CgA and that this interaction is enhanced under conditions of the TGN. Immobilized t-PA was incubated with ¹²⁵I-CgA. t-PA interacted specifically and saturably with CgA and the interaction was domain-specific, mediated by the EGF/finger and kringle 1 domains of t-PA and by a specific internal hydrophilic domain within CgA (KERTHQQKKHSSYEDELSEVL) as assessed by antibody and peptide competition studies. The interaction of t-PA with aggregated CgA complexes may play a role in the targeting of t-PA and its release from neurosecretory cells. These results may have broad implications for the regulation of local neurosecretory cell plasminogen activation under both normal physiological conditions and pathological conditions including cerebral ischemia.

Lower serum chromogranin B level is associated with type 1 diabetes and with type 2 diabetes patients with intensive conservative insulin treatment

BACKGROUND

Chromogranin B (CgB) plays an important role in the physiological insulin secretion of pancreatic beta cells. Serum CgB levels were investigated in type 1 and type 2 diabetes patients in a cross-sectional study.

METHODS

An observational cross-sectional study was performed with the inclusion of 94 control subjects, 100 type 1 and 100 type 2 diabetes patients, at the Metabolic Outpatient Clinic of the Department of Internal Medicine and Hematology, Semmelweis University. Serum CgB levels were measured with enzyme-linked immunosorbent assay.

RESULTS

Serum CgB level was lower in type 1 diabetes patients than in matched control subjects (p = 0.0241), while they were equal in type 2 diabetes patients and controls (p = 0.1698). The subgroup of type 2 diabetes patients who received intensive conservative insulin treatment had significantly lower CgB levels compared to those with other regimens of antidiabetic therapies (p = 0.0283).

CONCLUSION

The lower serum CgB levels in the patients with type 1 diabetes and the type 2 diabetes patients with progressed disease stage suggested that the CgB production might be decreased due to the beta cell destruction and depletion.

The infarction zone rather than the noninfarcted remodeling zone overexpresses angiotensin II receptor type 1 and is the main source of ventricular atrial natriuretic peptide

Chromogranin B and inositol 1,4,5-trisphosphate-associated calcium signaling leading to increased natriuretic peptide production has been described in cardiac hypertrophy. Here, we performed left anterior descending coronary artery ligation in rats as a model for systolic heart failure and examined protein and gene expression clusters in the infarcted and noninfarcted myocardium and moreover under treatment with metoprolol. We found that atrial natriuretic peptide gene transcription was significantly more elevated in the infarcted compared with the noninfarcted myocardium. Chromogranin B, which facilitates calcium release from internal stores through the inositol 1,4,5-trisphosphate receptor, was upregulated in both areas. Interestingly, angiotensin II receptor type 1 gene transcription was significantly upregulated in the infarcted and unchanged in the noninfarcted myocardium. Nuclear factor ĸappa B as a calcium-dependent transcription factor showed increased activity in the infarction zone. The β-adrenergic axis does not seem to be involved, as metoprolol treatment did not have a significant impact on any of these results. We conclude that region-specific upregulation of angiotensin II receptor type 1 is a major factor for increased atrial natriuretic peptide production in the infarcted anterior wall. This effect is most likely achieved through inositol 1,4,5-trisphosphate-mediated cytosolic calcium increase and subsequent nuclear factor ĸappa B activation, which is a known transcription factor for natriuretic peptides.

Exploring cardiac plasticity in teleost: the role of humoral modulation

The fish heart represents an established natural model for evaluating basic mechanisms of the coordinated physiological reactions which maintain cardiac steady-state. This is due to its relatively simple design, but also to its multilevel morpho-functional flexibility which allows adequate responses to a variety of intrinsic (body size and shape, swimming performance, etc.), and extrinsic (temperature, salinity, oxygen level, water chemistry, etc.) factors related to the animal life style. Nowadays, although many gaps are still present, a huge literature is available about the mechanisms that fine-tune fish cardiac performance, particularly in relation to the influence exerted by substances possessing cardio-modulatory properties. Based on these premises, this review will provide an overview of the existing current knowledge regarding the humoral control of cardiac performance in fish. The role of both classic (i.e. catecholamines, angiotensin II and natriuretic peptides), and emerging cardioactive substances (i.e. the chromogranin-A-derived peptides vasostatins, catestatin and serpinin) will be illustrated and discussed. Moreover, an example of cardiomodulation elicited by peptides (e.g., nesfatin-1) associated to the regulation of feeding and metabolism will be provided. The picture will hopefully emphasize the complex circuits that sustain fish cardiac performance, also highliting the power of the teleost heart as an experimental model to deciphering mechanisms that could be difficult to explore in more elaborated cardiac morpho-functional designs.

Chromogranin A and its fragments in cardiovascular, immunometabolic, and cancer regulation

Chromogranin A (CgA)-the index member of the chromogranin/secretogranin secretory protein family-is ubiquitously distributed in endocrine, neuroendocrine, and immune cells. Elevated levels of CgA-related polypeptides, consisting of full-length molecules and fragments, are detected in the blood of patients suffering from neuroendocrine tumors, heart failure, renal failure, hypertension, rheumatoid arthritis, and inflammatory bowel disease. Full-length CgA and various CgA-derived peptides, including vasostatin-1, pancreastatin, catestatin, and serpinin, are expressed at different relative levels in normal and pathological conditions and exert diverse, and sometime opposite, biological functions. For example, CgA is overexpressed in genetic hypertension, whereas catestatin is diminished. In rodents, the administration of catestatin decreases hypertension, cardiac contractility, obesity, atherosclerosis, and inflammation, and it improves insulin sensitivity. By contrast, pancreastatin is elevated in diabetic patients, and the administration of this peptide to obese mice decreases insulin sensitivity and increases inflammation. CgA and the N-terminal fragment of vasostatin-1 can enhance the endothelial barrier function, exert antiangiogenic effects, and inhibit tumor growth in animal models, whereas CgA fragments lacking the CgA C-terminal region promote angiogenesis and tumor growth. Overall, the CgA system, consisting of full-length CgA and its fragments, is emerging as an important and complex player in cardiovascular, immunometabolic, and cancer regulation.

The role of 5-hydroxyindoleacetic acid in neuroendocrine tumors: the journey so far

5-Hydroxyindole acetic acid (5-HIAA) is a surrogate marker for serotonin measurement and one of the first biochemical markers used in neuroendocrine tumors. In this review, we give a brief history of 5-HIAA and its precursor serotonin. We discuss its clinical utility and diagnostic performance in small intestinal neuroendocrine tumor and describe the challenges encountered during its analysis, historically performed in urine. The introduction of blood-based assays will help overcome some of the issues associated with its measurement in urine. The diagnostic performance of serum and plasma 5-HIAA has been shown to be comparable to that of urine 5-HIAA. Thus, analysis in either serum or plasma will provide a practical and convenient alternative to urine.

Modulation of the coronary tone in the expanding scenario of Chromogranin-A and its derived peptides

The cardiac function critically depends on an adequate myocardial oxygenation and on a correct coronary blood flow. Endothelial, hormonal and extravascular factors work together generating a fine balance between oxygen supply and oxygen utilization through the coronary circulation. Among the regulatory factors that contribute to the coronary tone, increasing attention is paid to the cardiac endocrines, such as chromogranin A, a prohormone for many biologically active peptides, including vasostatin and catestatin. In this review, we will summarize the available evidences about the coronary effects of these molecules, and their putative mechanism of action. Laboratory and clinical data on chromogranin A and its derived fragments will be analyzed in relation to the scenario of the endocrine heart, and of its putative clinical perspectives.

Chromogranin A: its known and possible roles in obstetrics and gynecology

Chromogranin A (CgA) is a prohormone initially extracted from the adrenal medulla, however, increased quantities of CgA are secreted by a wide array of human tissues in the course of a variety of disorders. This protein exhibits a number of interesting endocrine and non-endocrine functions. Here we briefly review the possible involvements of CgA in the areas covered by obstetrics and gynecology. Our account indicates the need to verify its association with the intrapartum fetal stress, and the involvement of CgA in the pathomechanisms of obstetric disorders related to placental dysfunction, as well as in the pathogenesis of endometrioid endometrial cancer as a hormonally regulated malignancy.

Catestatin regulates vesicular quanta through modulation of cholinergic and peptidergic (PACAPergic) stimulation in PC12 cells

We have previously shown that the chromogranin A (CgA)-derived peptide catestatin (CST: hCgA_352-372) inhibits nicotine-induced secretion of catecholamines from the adrenal medulla and chromaffin cells. In the present study, we seek to determine whether CST regulates dense core (DC) vesicle (DCV) quanta (catecholamine and chromogranin/secretogranin proteins) during acute (0.5-h treatment) or chronic (24-h treatment) cholinergic (nicotine) or peptidergic (PACAP, pituitary adenylyl cyclase activating polypeptide) stimulation of PC12 cells. In acute experiments, we found that both nicotine (60 μM) and PACAP (0.1 μM) decreased intracellular norepinephrine (NE) content and increased ³H-NE secretion, with both effects markedly inhibited by co-treatment with CST (2 μM). In chronic experiments, we found that nicotine and PACAP both reduced DCV and DC diameters and that this effect was likewise prevented by CST. Nicotine or CST alone increased expression of CgA protein and together elicited an additional increase in CgA protein, implying that nicotine and CST utilize separate signaling pathways to activate CgA expression. In contrast, PACAP increased expression of CgB and SgII proteins, with a further potentiation by CST. CST augmented the expression of tyrosine hydroxylase (TH) but did not increase intracellular NE levels, presumably due to its inability to cause post-translational activation of TH through serine phosphorylation. Co-treatment of CST with nicotine or PACAP increased quantal size, plausibly due to increased synthesis of CgA, CgB and SgII by CST. We conclude that CST regulates DCV quanta by acutely inhibiting catecholamine secretion and chronically increasing expression of CgA after nicotinic stimulation and CgB and SgII after PACAPergic stimulation.

Pain in labor assessed from two discomfort aspects: Physical pain intensity and psychological stress state

AIM

To assess two discomfort aspects of pain in labor, physical pain intensity and psychological stress state, we analyzed the association between the two parameters.

METHODS

Twenty-nine pregnant Japanese women with a singleton in 37-40 weeks of gestation were analyzed. Physical pain intensity was examined by the Numeric Rating Scale (NRS). Psychological stress state was measured by chromogranin A (CgA) in saliva. Data were collected thrice during labor (at 4-6 cm and 10 cm of cervical dilatation and immediately after delivery) and were accumulated from 4-6 cm and 10 cm of cervical dilatation. The study was approved by the Ethics Committees of Osaka University and Tokyo Women's Medical University.

RESULTS

The median NRS score (10, IQR = 10-18) and the median CgA in saliva (8.0, IQR = 4.3-12.0) pmol/mg at 10 cm of cervical dilatation were significantly higher than those at the other two time points (P < 0.05). Although there were no correlations between NRS scores and concentrations of CgA in saliva at the three time points, there was a significant correlation between accumulated NRS and accumulated CgA in saliva (r = 0.68, P = 0.000). There was a significant difference in the accumulated NRS scores (P = 0.005) but not in the accumulated concentrations of CgA between primiparae and multiparae.

CONCLUSION

Women in labor perceived severe pain and psychological stress with similar patterns during labor. However, these parameters were independent and need to be measured to evaluate these two discomfort aspects.

Catestatin as a Target for Treatment of Inflammatory Diseases

It is increasingly clear that inflammatory diseases and cancers are influenced by cleavage products of the pro-hormone chromogranin A (CgA), such as the 21-amino acids long catestatin (CST). The goal of this review is to provide an overview of the anti-inflammatory effects of CST and its mechanism of action. We discuss evidence proving that CST and its precursor CgA are crucial for maintaining metabolic and immune homeostasis. CST could reduce inflammation in various mouse models for diabetes, colitis and atherosclerosis. In these mouse models, CST treatment resulted in less infiltration of immune cells in affected tissues, although in vitro monocyte migration was increased by CST. Both in vivo and in vitro, CST can shift macrophage differentiation from a pro- to an anti-inflammatory phenotype. Thus, the concept is emerging that CST plays a role in tissue homeostasis by regulating immune cell infiltration and macrophage differentiation. These findings warrant studying the effects of CST in humans and make it an interesting therapeutic target for treatment and/or diagnosis of various metabolic and immune diseases.

Generation of Scaffold-free, Three-dimensional Insulin Expressing Pancreatoids from Mouse Pancreatic Progenitors In Vitro

The pancreas is a complex organ composed of many different cell types that work together to regulate blood glucose homeostasis and digestion. These cell types include enzyme-secreting acinar cells, an arborized ductal system responsible for the transportation of enzymes to the gut, and hormone-producing endocrine cells. Endocrine beta-cells are the sole cell type in the body that produce insulin to lower blood glucose levels. Diabetes, a disease characterized by a loss or the dysfunction of beta-cells, is reaching epidemic proportions. Thus, it is essential to establish protocols to investigate beta-cell development that can be used for screening purposes to derive the drug and cell-based therapeutics. While the experimental investigation of mouse development is essential, in vivo studies are laborious and time-consuming. Cultured cells provide a more convenient platform for screening; however, they are unable to maintain the cellular diversity, architectural organization, and cellular interactions found in vivo. Thus, it is essential to develop new tools to investigate pancreatic organogenesis and physiology. Pancreatic epithelial cells develop in the close association with mesenchyme from the onset of organogenesis as cells organize and differentiate into the complex, physiologically competent adult organ. The pancreatic mesenchyme provides important signals for the endocrine development, many of which are not well understood yet, thus difficult to recapitulate during the in vitro culture. Here, we describe a protocol to culture three-dimensional, cellular complex mouse organoids that retain mesenchyme, termed pancreatoids. The e10.5 murine pancreatic bud is dissected, dissociated, and cultured in a scaffold-free environment. These floating cells self-assemble with mesenchyme enveloping the developing pancreatoid and a robust number of endocrine beta-cells developing along with the acinar and the duct cells. This system can be used to study the cell fate determination, structural organization, and morphogenesis, cell-cell interactions during organogenesis, or for the drug, small molecule, or genetic screening.

Chromogranin-A and its derived peptides and their pharmacological effects during intestinal inflammation

The gastrointestinal tract is the largest endocrine organ that produces a broad range of active peptides. Mucosal changes during inflammation alter the distribution and products of enteroendocrine cells (EECs) that play a role in immune activation and regulation of gut homeostasis by mediating communication between the nervous, endocrine and immune systems. Patients with inflammatory bowel disease (IBD) typically have altered expression of chromogranin (CHG)-A (CHGA), a major soluble protein secreted by EECs that functions as a pro-hormone. CHGA gives rise to several bioactive peptides that have direct or indirect effects on intestinal inflammation. In IBD, CHGA and its derived peptides are correlated with the disease activity. In this review we describe the potential immunomodulatory roles of CHGA and its derived peptides and their clinical relevance during the progression of intestinal inflammation. Targeting CHGA and its derived peptides could be of benefit for the diagnosis and clinical management of IBD patients.

An observational analysis of insulinoma from a single institution

BACKGROUND

Insulinoma is the commonest functioning pancreatic neuroendocrine tumor causing hyperinsulinemic hypoglycemia.

AIM

This study is aimed to evaluate the clinical features, preoperative laboratory and imaging diagnosis and pathologic findings of insulinoma.

METHODS

Data of the patients from 2001 to 2016 diagnosed as insulinoma in Tongji Hospital, China were retrospectively extracted and analyzed.

RESULTS

A total of 40 patients were diagnosed as insulinoma with a male/female ratio of 0.68:1. The median onset age was 46.5 years. Nearly all the included patients presented neurological symptoms and 60% presented autonomic symptoms. More than 95% of the patients met the functional European Neuroendocrine Tumor Society criteria including glucose, insulin and C-peptide levels. The preoperative detection rates of ultrasonography, enhanced computed tomography, magnetic resonance imaging, and endoscopic ultrasonography were 60.50%, 84.95%, 80% and 83.3% respectively. The joint imaging examinations can markedly increase the detection rate. The mean tumor size was 1.89 ± 0.72 cm. Ki-67 index by histopathological diagnosis were all less than 20%. The positive rates of insulin, synaptophysin and chromogranin A were close to 100%.

CONCLUSION

Laboratory tests of glucose, insulin and C-peptide are reliable for preoperative diagnosis. Combination of the imaging examinations can improve the diagnosis.

Amyloid beta peptides, locus coeruleus-norepinephrine system and dense core vesicles

The evolution of peptidergic signaling systems in the central nervous system serves a distinct and crucial role in brain processes and function. The diversity of physiological peptides and the complexity of their regulation and secretion from the dense core vesicles (DCV) throughout the brain is a topic greatly in need of investigation, though recent years have shed light on cellular and molecular mechanisms that are summarized in this review. Here, we focus on the convergence of peptidergic systems onto the Locus Coeruleus (LC), the sole provider of norepinephrine (NE) to the cortex and hippocampus, via large DCV. As the LC-NE system is one of the first regions of the brain to undergo degeneration in Alzheimer's Disease (AD), and markers of DCV have consistently been demonstrated to have biomarker potential for AD progression, here we summarize the current literature linking the LC-NE system with DCV dysregulation and Aβ peptides. We also include neuroanatomical data suggesting that the building blocks of senile plaques, Aβ monomers, may be localized to DCV of the LC and noradrenergic axon terminals of the prefrontal cortex. Finally, we explore the putative consequences of chronic stress on Aβ production and the role that DCV may play in LC degeneration. Clinical data of immunological markers of DCV in AD patients are discussed.

Development of a polarized pancreatic ductular cell epithelium for physiological studies

Pancreatic ductular epithelial cells comprise the majority of duct cells in pancreas, control cystic fibrosis transmembrane conductance regulator (CFTR)-dependent bicarbonate ([Formula: see text]) secretion, but are difficult to grow as a polarized monolayer. Using NIH-3T3-J2 fibroblast feeder cells and a Rho-associated kinase inhibitor, we produced well-differentiated and polarized porcine pancreatic ductular epithelial cells. Cells grown on semipermeable filters at the air-liquid interface developed typical epithelial cell morphology and stable transepithelial resistance and expressed epithelial cell markers (zona occludens-1 and β-catenin), duct cell markers (SOX-9 and CFTR), but no acinar (amylase) or islet cell (chromogranin) markers. Polarized cells were studied in Ussing chambers bathed in Krebs-Ringer [Formula: see text] solution at 37°C gassed with 5% CO₂ to measure short-circuit currents ( I_sc). Ratiometric measurement of extracellular pH was performed with fluorescent SNARF-conjugated dextran at 5% CO₂. Cells demonstrated a baseline I_sc (12.2 ± 3.2 μA/cm²) that increased significantly in response to apical forskolin-IBMX (∆ I_sc: 35.4 ± 3.8 μA/cm², P < 0.001) or basolateral secretin (∆ I_sc: 31.4 ± 2.5 μA/cm², P < 0.001), both of which increase cellular levels of cAMP. Subsequent addition of apical GlyH-101, a CFTR inhibitor, decreased the current (∆ I_sc: 20.4 ± 3.8 μA/cm², P < 0.01). Extracellular pH and [Formula: see text] concentration increased significantly after forskolin-IBMX (pH: 7.18 ± 0.23 vs. 7.53 ± 0.19; [Formula: see text] concentration, 14.5 ± 5.9 vs. 31.8 ± 13.4 mM; P < 0.05 for both). We demonstrate the development of a polarized pancreatic ductular epithelial cell epithelium with CFTR-dependent [Formula: see text] secretion in response to secretin and cAMP. This model is highly relevant, as porcine pancreas physiology is very similar to humans and pancreatic damage in the cystic fibrosis pig model recapitulates that of humans. NEW & NOTEWORTHY Pancreas ductular epithelial cells control cystic fibrosis transmembrane conductance regulator (CFTR)-dependent bicarbonate secretion. Their function is critical because when CFTR is deficient in cystic fibrosis bicarbonate secretion is lost and the pancreas is damaged. Mechanisms that control pancreatic bicarbonate secretion are incompletely understood. We generated well-differentiated and polarized porcine pancreatic ductular epithelial cells and demonstrated feasibility of bicarbonate secretion. This novel method will advance our understanding of pancreas physiology and mechanisms of bicarbonate secretion.

Secretogranin III: a diabetic retinopathy-selective angiogenic factor

Secretogranin III (Scg3) is a member of the granin protein family that regulates the biogenesis of secretory granules. Scg3 was recently discovered as an angiogenic factor, expanding its functional role to extrinsic regulation. Unlike many other known angiogenic factors, the pro-angiogenic actions of Scg3 are restricted to pathological conditions. Among thousands of quantified endothelial ligands, Scg3 has the highest binding activity ratio to diabetic vs. healthy mouse retinas and lowest background binding to normal vessels. In contrast, vascular endothelial growth factor binds to and stimulates angiogenesis of both diabetic and control vasculature. Consistent with its role in pathological angiogenesis, Scg3-neutralizing antibodies alleviate retinal vascular leakage in mouse models of diabetic retinopathy and retinal neovascularization in oxygen-induced retinopathy mice. This review summarizes our current knowledge of Scg3 as a regulatory protein of secretory granules, highlights its new role as a highly disease-selective angiogenic factor, and envisions Scg3 inhibitors as "selective angiogenesis blockers" for targeted therapy.

What's New in Endocrinology: The Chromaffin Cell

Recent advances in understanding the intracellular and intercellular features of adrenal chromatin cells as stress transducers are reviewed here, along with their implications for endocrine function in other tissues and organs participating in endocrine regulation in the mammalian organism.

Homeostatic effect of laughter on diabetic cardiovascular complications: The myth turned to fact

AIMS

Laughter has been used for centuries to alleviate pain in morbid conditions. It was not until 1976 that scientists thought about laughter as a form of therapy that can modulate hormonal and immunological parameters that affect the outcome of many serious diseases. Moreover, laughter therapy was shown to be beneficial in type 2 diabetes mellitus (T2DM) by delaying the onset of many diabetic complications. Laughter is also described to influence the cardiovascular and endothelial functions and thus may protect against diabetic cardiovascular complications. In this review, we outline the different biochemical, physiological and immunological mechanisms by which laughter may influence the overall state of wellbeing and enhance disease prognosis. We also focus on the biological link between laughter therapy and diabetic cardiovascular complications as well as the underlying mechanisms involved in T2DM.

METHODS

Reviewing all the essential databases for "laughter" and "type 2 diabetes mellitus".

RESULTS

Although laughter therapy is still poorly investigated, recent studies show that laughter may retard the onset of diabetic complications, enhance cardiovascular functions and rectify homeostatic abnormalities associated with T2DM.

CONCLUSIONS

Laughter therapy is effective in delaying diabetic complications and should be used as an adjuvant therapy.

Chromogranin A as circulating marker for diagnosis and management of neuroendocrine neoplasms: more flaws than fame

Owing to the heterogeneity of neuroendocrine neoplasms (NENs), the availability of reliable circulating markers is critical for improving diagnostics, prognostic stratification, follow-up and definition of treatment strategy. This review is focused on chromogranin A (CgA), a hydrophilic glycoprotein present in large dense core vesicles of neuroendocrine cells. Despite being long identified as the most useful NEN-related circulating marker, clinical application of CgA is controversial. CgA assays still lack standardization, thus hampering not only clinical management but also the comparison between different analyses. In the diagnostic setting, clinical utility of CgA is limited as hampered by (a) the variety of oncological and non-oncological conditions affecting marker levels, which impairs specificity; (b) the fact that 30-50% of NENs show normal CgA, which impairs sensitivity. Regarding the prognostic phase, there is prospective evidence which demonstrates that advanced NENs secreting CgA have poorer outcome, as compared with those showing non-elevated marker levels. Although the identification of cut-offs allowing a proper risk stratification of CgA-secreting patients has not been performed, this represents the most important clinical application of the marker. By contrast, based on prospective studies, the trend of elevated circulating CgA does not represent a valid indicator of morphological evolution and has therefore no utility for the follow-up phase. Ultimately, current knowledge about the role of the marker for the definition of treatment strategy is poor and is limited by the small number of available studies, their prevalent retrospective nature and the absence of control groups of untreated subjects.

Chromogranins: from discovery to current times

The discovery in 1953 of the chromaffin granules as co-storage of catecholamines and ATP was soon followed by identification of a range of uniquely acidic proteins making up the isotonic vesicular storage complex within elements of the diffuse sympathoadrenal system. In the mid-1960s, the enzymatically inactive, major core protein, chromogranin A was shown to be exocytotically discharged from the stimulated adrenal gland in parallel with the co-stored catecholamines and ATP. A prohormone concept was introduced when one of the main storage proteins collectively named granins was identified as the insulin release inhibitory polypeptide pancreastatin. A wide range of granin-derived biologically active peptides have subsequently been identified. Both chromogranin A and chromogranin B give rise to antimicrobial peptides of relevance for combat of pathogens. While two of the chromogranin A-derived peptides, vasostatin-I and pancreastatin, are involved in modulation of calcium and glucose homeostasis, respectively, vasostatin-I and catestatin are important modulators of endothelial permeability, angiogenesis, myocardial contractility, and innate immunity. A physiological role is now evident for the full-length chromogranin A and vasostatin-I as circulating stabilizers of endothelial integrity and in protection against myocardial injury. The high circulating levels of chromogranin A and its fragments in patients suffering from various inflammatory diseases have emerged as challenges for future research and clinical applications.

Chromogranin A regulates vesicle storage and mitochondrial dynamics to influence insulin secretion

Chromogranin A (CgA) is a prohormone and a granulogenic factor that regulates secretory pathways in neuroendocrine tissues. In β-cells of the endocrine pancreas, CgA is a major cargo in insulin secretory vesicles. The impact of CgA deficiency on the formation and exocytosis of insulin vesicles is yet to be investigated. In addition, no literature exists on the impact of CgA on mitochondrial function in β-cells. Using three different antibodies, we demonstrate that CgA is processed to vasostatin- and catestatin-containing fragments in pancreatic islet cells. CgA deficiency in Chga-KO islets leads to compensatory overexpression of chromogranin B, secretogranin II, SNARE proteins and insulin genes, as well as increased insulin protein content. Ultrastructural studies of pancreatic islets revealed that Chga-KO β-cells contain fewer immature secretory granules than wild-type (WT) control but increased numbers of mature secretory granules and plasma membrane-docked vesicles. Compared to WT control, CgA-deficient β-cells exhibited increases in mitochondrial volume, numerical densities and fusion, as well as increased expression of nuclear encoded genes (Ndufa9, Ndufs8, Cyc1 and Atp5o). These changes in secretory vesicles and the mitochondria likely contribute to the increased glucose-stimulated insulin secretion observed in Chga-KO mice. We conclude that CgA is an important regulator for coordination of mitochondrial dynamics, secretory vesicular quanta and GSIS for optimal secretory functioning of β-cells, suggesting a strong, CgA-dependent positive link between mitochondrial fusion and GSIS.

Granin-derived peptides

The granin family comprises altogether 7 different proteins originating from the diffuse neuroendocrine system and elements of the central and peripheral nervous systems. The family is dominated by three uniquely acidic members, namely chromogranin A (CgA), chromogranin B (CgB) and secretogranin II (SgII). Since the late 1980s it has become evident that these proteins are proteolytically processed, intragranularly and/or extracellularly into a range of biologically active peptides; a number of them with regulatory properties of physiological and/or pathophysiological significance. The aim of this comprehensive overview is to provide an up-to-date insight into the distribution and properties of the well established granin-derived peptides and their putative roles in homeostatic regulations. Hence, focus is directed to peptides derived from the three main granins, e.g. to the chromogranin A derived vasostatins, betagranins, pancreastatin and catestatins, the chromogranin B-derived secretolytin and the secretogranin II-derived secretoneurin (SN). In addition, the distribution and properties of the chromogranin A-derived peptides prochromacin, chromofungin, WE14, parastatin, GE-25 and serpinins, the CgB-peptide PE-11 and the SgII-peptides EM66 and manserin will also be commented on. Finally, the opposing effects of the CgA-derived vasostatin-I and catestatin and the SgII-derived peptide SN on the integrity of the vasculature, myocardial contractility, angiogenesis in wound healing, inflammatory conditions and tumors will be discussed.

Muscle injury, impaired muscle function and insulin resistance in Chromogranin A-knockout mice

Chromogranin A (CgA) is widely expressed in endocrine and neuroendocrine tissues as well as in the central nervous system. We observed CgA expression (mRNA and protein) in the gastrocnemius (GAS) muscle and found that performance of CgA-deficient Chga-KO mice in treadmill exercise was impaired. Supplementation with CgA in Chga-KO mice restored exercise ability suggesting a novel role for endogenous CgA in skeletal muscle function. Chga-KO mice display (i) lack of exercise-induced stimulation of pAKT, pTBC1D1 and phospho-p38 kinase signaling, (ii) loss of GAS muscle mass, (iii) extensive formation of tubular aggregates (TA), (iv) disorganized cristae architecture in mitochondria, (v) increased expression of the inflammatory cytokines Tnfα, Il6 and Ifnγ, and fibrosis. The impaired maximum running speed and endurance in the treadmill exercise in Chga-KO mice correlated with decreased glucose uptake and glycolysis, defects in glucose oxidation and decreased mitochondrial cytochrome C oxidase activity. The lack of adaptation to endurance training correlated with the lack of stimulation of p38MAPK that is known to mediate the response to tissue damage. As CgA sorts proteins to the regulated secretory pathway, we speculate that lack of CgA could cause misfolding of membrane proteins inducing aggregation of sarcoplasmic reticulum (SR) membranes and formation of tubular aggregates that is observed in Chga-KO mice. In conclusion, CgA deficiency renders the muscle energy deficient, impairs performance in treadmill exercise and prevents regeneration after exercise-induced tissue damage.