Regulation of endothelial cell shape and barrier function by chromogranin A

A complex role of chromogranin A and its peptides in inflammation, autoimmunity, and infections

Chromogranin A (CgA), mostly known as a nonspecific neuroendocrine tumor marker, was the first glycoprotein from the granin family characterized as a prohormone for various bioactive peptides including vasostatin I/II (VS-I, VS-II), catestatin (CST), chromofungin (CHR), pancreastatin (PST), WE-14, and others. CgA and its derivatives present various functions, often antagonistic, in maintaining body homeostasis and influencing the immune system. This review aims to summarize the not fully understood role of CgA and its derivatives in inflammation, autoimmunity, and infections. CgA seems to be involved in the complex pathophysiology of cardiovascular disorders, neurodegenerative diseases, and other conditions where immune system dysfunction plays a role in the onset and development of the disease (e.g. systemic lupus erythematosus (SLE), inflammatory bowel disease (IBD), or rheumatoid arthritis (RA)). However, the direct immunomodulatory role of CgA is difficult to assess since many of its activities may be linked with its peptides. CST and VS-I are considered anti-inflammatory molecules, due to M2 macrophage polarization stimulation and downregulation of certain proinflammatory cytokines. Conversely, PST is reported to stimulate proinflammatory M1 macrophage polarization and Th1 lymphocyte response. Thus, the final effects of CgA in inflammation may depend on its cleavage pattern. Additionally, peptides like CST, VS-I, or CHR exert direct antimicrobial/antifungal activities. CgA, WE-14, and other less-known CgA-derived peptides have also been reported to trigger autoimmune responses, highly studied in type 1 diabetes mellitus. Overall, CgA and its derivatives have an interesting but complex role in immunity, however, their specific roles require further research.

Abnormalities in endocrine and immune cells are correlated in dextran‑sulfate‑sodium‑induced colitis in rats

The interaction between the gut hormones and the immune system has been suggested to serve an important role in the pathophysiology of inflammatory bowel disease. The aims of the present study were to elucidate the possible abnormalities in the colonic endocrine cells in rats with dextran sodium sulfate (DSS)-induced colitis, and to determine whether they are correlated with alterations in the immune cells. A total of 24 male Wistar rats were divided into two groups: Control and DSS-induced colitis. Colonic tissues were harvested via postmortem laparotomy from all of the animals at the end of the experimental period, and fixed and sectioned for histology. The colonic endocrine and immune cells in those tissue samples were immunostained and their densities quantified by computerized image analysis. The densities of chromogranin A, serotonin, peptide YY and oxyntomodulin cells were significantly higher, and those of pancreatic peptide and somatostatin cells were lower in rats with DSS-induced colitis than in the controls. The densities of mucosal leukocytes, T and B lymphocytes, macrophages/monocytes, and mast cells were significantly higher than in the controls, and these changes were closely associated with the aforementioned changes in all endocrine cell types. These observations indicate an interaction between intestinal hormones and the immune system as represented by immune cells.

Changes in enteroendocrine and immune cells following colitis induction by TNBS in rats

Approximately 3.6 million individuals suffer from inflammatory bowel disease (IBD) in the western world, with an annual global incidence rate of 3–20 cases/100,000 individuals. The etiology of IBD is unknown, and the currently available treatment options are not satifactory for long-term treatment. Patients with inflammatory bowel disease present with abnormalities in multiple intestinal endocrine cell types, and a number of studies have suggested that interactions between gut hormones and immune cells may serve a pivotal role in the pathophysiology of IBD. The aim of the present study was to investigate alterations in colonic endocrine cells in a rat model of IBD. A total of 30 male Wistar rats were divided into control and trinitrobenzene sulfonic acid (TNBS)-induced colitis groups. Colonoscopies were performed in the control and TNBS groups at day 3 following the induction of colitis, and colonic tissues were collected from all animals. Colonic endocrine and immune cells in the obtained tissue samples were immunostained and their densities were quantified. The densities of chromogranin A, peptide YY, and pancreatic polypeptide-producing cells were significantly lower in the TNBS group compared with the control group, whereas the densities of serotonin, oxyntomodulin, and somatostatin-producing cells were significantly higher in the TNBS group. The densities of mucosal leukocytes, B/T-lymphocytes, T-lymphocytes, B-lymphocytes, macrophages/monocytes and mast cells were significantly higher in the TNBS group compared with the controls, and these differences were strongly correlated with alterations in all endocrine cell types. In conclusion, the results suggest the presence of interactions between intestinal hormones and immune cells.

Effects of AP‑1 and NF‑κB inhibitors on colonic endocrine cells in rats with TNBS‑induced colitis

Interactions between intestinal neuroendocrine peptides/amines and the immune system appear to have an important role in the pathophysiology of inflammatory bowel disease (IBD). The present study investigated the effects of activator protein (AP)‑1 and nuclear factor (NF)‑κB inhibitors on inflammation‑induced alterations in enteroendocrine cells. A total of 48 male Wistar rats were divided into the following four groups (n=12 rats/group): Control, trinitrobenzene sulfonic acid (TNBS)‑induced colitis only (TNBS group), TNBS‑induced colitis with 3‑[(dodecylthiocarbonyl)-methyl]-glutarimide (DTCM‑G) treatment (DTCM‑G group), and TNBS‑induced colitis with dehydroxymethylepoxyquinomicin (DHMEQ) treatment (DHMEQ group). A total of 3 days following administration of TNBS, the rats were treated as follows: The control and TNBS groups received 0.5 ml vehicle (0.5% carboxymethyl cellulose; CMC), respectively; the DTCM‑G group received DTCM‑G (20 mg/kg body weight) in 0.5% CMC; and the DHMEQ group received DHMEQ (15 mg/kg body weight) in 0.5% CMC. All injections were performed intraperitoneally twice daily for 5 days. The rats were sacrificed, and tissue samples obtained from the colon were examined histopathologically and immunohistochemically. Inflammation was evaluated using a scoring system. In addition, the sections were immunostained for chromogranin A (CgA), serotonin, peptide YY (PYY), oxyntomodulin, pancreatic polypeptide (PP) and somatostatin, and immunostaining was quantified using image‑analysis software. The density of cells expressing CgA, PYY and PP was significantly lower in the TNBS group compared with in the control group, whereas the density of cells expressing serotonin, oxyntomodulin and somatostatin was significantly higher in the TNBS group compared with in the control group. None of the endocrine cell types differed significantly between the control group and either the DTCM‑G or DHMEQ groups. All of the colonic endocrine cell types were affected in rats with TNBS‑induced colitis. The expression density of these endocrine cell types was restored to control levels following treatment with AP‑1 or NF‑κB inhibitors. These results indicated that the immune system and enteroendocrine cells interact in IBD.

Treatment with novel AP-1 and NF-κB inhibitors restores the colonic endocrine cells to normal levels in rats with DSS-induced colitis

The aim of this study was to determine the effects of two anti-inflammatory agents on the abnormalities in colonic endocrine cells in dextran sodium sulfate (DSS)-induced colitis. Colitis was induced in male Wistar rats (n=45) using DSS; a further 15 rats without colitis were included in a healthy control group. The animals with DSS-induced colitis were randomly divided into 3 treatment groups as follows: i) DSS group, rats were treated with 0.5 ml of 0.5% carboxymethyl cellulose (CMC); ii) DSS‑G group, rats were treated with 3-[(dodecylthiocarbonyl)‑methyl]‑glutarimide (DTCM‑G), a novel activator protein 1 (AP-1) inhibitor, 20 mg/kg in CMC; and iii) DSS‑Q group, rats were treated with dehydroxymethylepoxyquinomicin, a nuclear factor κB (NF-κB) inhibitor, 15 mg/kg in CMC. The treatments were administered intraperitoneally, twice daily for 5 days, after which the animals were sacrificed and tissue samples from the colon were immunostained for chromogranin A (CgA), serotonin, peptide YY (PYY), enteroglucagon, pancreatic polypeptide (PP), somatostatin, leukocytes, B/T lymphocytes, B lymphocytes, T lymphocytes, macrophages/monocytes and mast cells. The densities of these endocrine and immune cells were quantified by computer‑aided image analysis. The densities of CgA-, serotonin-, PYY- and enteroglucagon-producing cells were significantly higher, and those of PP- and somatostatin-producing cells were significantly lower in the DSS‑G, DSS‑Q and control groups than in the DSS group. The densities of all the immune cells were lower in the DSS‑G, DSS‑Q and control groups than in the DSS group. The densities of all endocrine cell types and immune cells in both the DSS groups treated with anti‑inflammatory agents were restored to control levels. In conclusion, our data demonstrate that there is an interaction between endocrine and immune cells during inflammation. This interaction with subsequent changes in endocrine cells is responsible for the clinical manifestation of colitis symptoms.

The surging role of Chromogranin A in cardiovascular homeostasis

Together with Chromogranin B and Secretogranins, Chromogranin A (CGA) is stored in secretory (chromaffin) granules of the diffuse neuroendocrine system and released with noradrenalin and adrenalin. Co-stored within the granule together with neuropeptideY, cardiac natriuretic peptide hormones, several prohormones and their proteolytic enzymes, CGA is a multifunctional protein and a major marker of the sympatho-adrenal neuroendocrine activity. Due to its partial processing to several biologically active peptides, CGA appears an important pro-hormone implicated in relevant modulatory actions on endocrine, cardiovascular, metabolic, and immune systems through both direct and indirect sympatho-adrenergic interactions. As a part of this scenario, we here illustrate the emerging role exerted by the full-length CGA and its three derived fragments, i.e., Vasostatin 1, catestatin and serpinin, in the control of circulatory homeostasis with particular emphasis on their cardio-vascular actions under both physiological and physio-pathological conditions. The Vasostatin 1- and catestatin-induced cardiodepressive influences are achieved through anti-beta-adrenergic-NO-cGMP signaling, while serpinin acts like beta1-adrenergic agonist through AD-cAMP-independent NO signaling. On the whole, these actions contribute to widen our knowledge regarding the sympatho-chromaffin control of the cardiovascular system and its highly integrated “whip-brake” networks.

Chromogranin A as a biomarker of disease activity and biologic therapy in inflammatory bowel disease: a prospective observational study

OBJECTIVE

To access the correlation of Chromogranin A (CgA) with inflammatory bowel disease (IBD) activity and responsiveness to medical therapy.

MATERIAL AND METHODS

A prospective observational study was conducted in 56 patients with moderate ulcerative colitis (UC) or Crohn's disease (CD) (UC, n = 29, CD, n = 27), 17 patients with irritable bowel syndrome and predominant diarrhea (IBS-D) and 40 healthy volunteers. IBD patients were treated by biologics (infliximab or adalimumab) or conventional agents (aminosalicylates, thiopurines or methotrexate and steroids) and were classified according to their treatment in two groups. Serum CgA was measured at baseline and 4-week posttreatment period.

RESULTS

Serum CgA was significantly higher in IBD patients than in those with IBS-D or healthy volunteers (p < 0.01). Furthermore, serum CgA was markedly increased in CD patients than in UC patients (p < 0.01). CgA value was significantly reduced in 'biologic' group (24 IBD patients, UC, n = 15, CD, n = 9) at 4-week posttreatment period (p < 0.01), while 18/24 (72%) patients were already in remission during that time. In contrast, CgA value was significantly increased in the 'conventional' treatment group (32 IBD patients, UC, n = 14, CD, n = 18) between the two visits (p < 0.01), although 22/32 (69%) patients were in remission during the 4-week posttreatment period.

CONCLUSION

CgA appears to be a reliable marker of disease activity in IBD patients and especially in those who received biologic therapy. IBS-D patients presented normal CgA values.

Increased N-terminal CgA in circulation associated with cardiac reperfusion in pigs

Aim: Acute myocardial infarction causes neurohumoral activation characterized by increased sympathetic activity. CgA is a protein released during sympathoadrenal stress from neuroendocrine tissue. Recently, increased CgA concentrations in circulation have been reported and suggested to be an independent predictor of mortality after acute myocardial infarction. Materials & methods: Eighteen pigs underwent 1 h of regional myocardial ischemia followed by 3 h of reperfusion. Blood samples were collected every hour and plasma CgA was measured with two radioimmunoassays. Results: We found a 30% increase in plasma N-terminal CgA 1 h after re-establishment of coronary blood supply. On the other hand, plasma pancreastatin did not change in response to ischemia or reperfusion but decreased during the entire experiment. Conclusion: Our results suggest a differentiated CgA response in myocardial reperfusion after local cardiac anoxia that may reflect tissue-specific post-translational processing and release.

Chromogranin A cell density as a diagnostic marker for lymphocytic colitis

BACKGROUND

Lymphocytic colitis (LC) can be mistakenly diagnosed as irritable bowel syndrome (IBS). In a previous study on IBS, some patients showed extremely high colonic chromogranin A cell density. Further examination of these patients showed that they suffered from LC.

AIMS

To investigate whether chromogranin A cell density is increased in LC patients and to examine the possibility of using this increase as a marker for the diagnosis of LC.

METHODS

Fifty-seven patients diagnosed with LC and 54 controls were included in the study. Biopsies from the right and left colon were obtained from both patients and controls, which were immunostained using the Avidin-biotin-complex method for chromogranin A, and cell density was quantified.

RESULTS

In both the right and left colon of patients with LC, the density of chromogranin A was significantly higher than in controls. This increase in chromogranin A cells occurs whether the number of these cells is expressed as number/mm(2) epithelium or as number/field. Chromogranin A cell density for the right and left colon expressed as number of cells/mm(2) epithelium or as cell number/field showed a high sensitivity and specificity as a diagnostic marker for LC.

CONCLUSIONS

Chromogranin A is a common marker for endocrine cells, and the present finding suggests that colonic hormones are involved in the pathophysiology of LC. The chromogranin cell density seems to be a good diagnostic marker with high sensitivity and specificity in both the right and left colon, thus sigmoidoscopy can be used in the diagnosis of LC using with this marker.

Chromogranin A binds to αvβ6-integrin and promotes wound healing in mice

Chromogranin A (CgA), a secretory protein expressed by many neuroendocrine cells, neurons, cardiomyocytes, and keratinocytes, is the precursor of various peptides that regulate the carbohydrate/lipid metabolism and the cardiovascular system. We have found that CgA, locally administered to injured mice, can accelerate keratinocyte proliferation and wound healing. This biological activity was abolished by the Asp(45)Glu mutation. CgA and its N-terminal fragments, but not the corresponding Asp(45)Glu mutants, could selectively recognize the αvβ6-integrin on keratinocytes (a cell-adhesion receptor that is up-regulated during wound healing) and regulate keratinocyte adhesion, proliferation, and migration. No binding was observed to other integrins such as αvβ3, αvβ5, αvβ8, α5β1, α1β1, α3β1, α6β4, α6β7 and α9β1. Structure-activity studies showed that the entire CgA(39-63) region is crucial for αvβ6 recognition (K(i) = 7 nM). This region contains an RGD site (residues CgA(43-45)) followed by an amphipathic α-helix (residues CgA(47-63)), both crucial for binding affinity and selectivity. These results suggest that the interaction of the RGD/α-helix motif of CgA with αvβ6 regulates keratinocyte physiology in wound healing.

Genes involved in systemic and arterial bed dependent atherosclerosis--Tampere Vascular study

Background

Atherosclerosis is a complex disease with hundreds of genes influencing its progression. In addition, the phenotype of the disease varies significantly depending on the arterial bed.

Methodology/Principal Findings

We characterized the genes generally involved in human advanced atherosclerotic (AHA type V–VI) plaques in carotid and femoral arteries as well as aortas from 24 subjects of Tampere Vascular study and compared the results to non-atherosclerotic internal thoracic arteries (n=6) using genome-wide expression array and QRT-PCR. In addition we determined genes that were typical for each arterial plaque studied. To gain a comprehensive insight into the pathologic processes in the plaques we also analyzed pathways and gene sets dysregulated in this disease using gene set enrichment analysis (GSEA). According to the selection criteria used (>3.0 fold change and p-value <0.05), 235 genes were up-regulated and 68 genes down-regulated in the carotid plaques, 242 genes up-regulated and 116 down-regulated in the femoral plaques and 256 genes up-regulated and 49 genes down-regulated in the aortic plaques. Nine genes were found to be specifically induced predominantly in aortic plaques, e.g., lactoferrin, and three genes in femoral plaques, e.g., chondroadherin, whereas no gene was found to be specific for carotid plaques. In pathway analysis, a total of 28 pathways or gene sets were found to be significantly dysregulated in atherosclerotic plaques (false discovery rate [FDR] <0.25).

Conclusions

This study describes comprehensively the gene expression changes that generally prevail in human atherosclerotic plaques. In addition, site specific genes induced only in femoral or aortic plaques were found, reflecting that atherosclerotic process has unique features in different vascular beds.

Chromogranin A: a novel factor acting at the cross road between the neuroendocrine and the cardiovascular systems

Chromogranin A (CHGA) is a secretory protein stored in and released from neurons and cells of the diffuse neuroendocrine system. Cells of the adrenal medulla and adrenergic terminals are a main source of CHGA but also myocardial cells produce it under stress conditions. After secretion, CHGA is cleaved into several biologically active fragments, including vasostatins and catestatin. CHGA and its proteolytic peptides exert a broad spectrum of activities on the cardiovascular system. They act on blood pressure by controlling the vascular tone and the cardiac inotropic and chronotropic function. CHGA revealed to be a sensitive marker of myocardial dysfunction, with a high predictive power of morbidity and mortality in heart failure and ischemic heart disease. In addition, CHGA has been involved in the control of sustained endothelial inflammation and has been shown to be a good marker of persistent vascular inflammation in rheumatologic disorders affecting vessels.

Role of vasostatin-1 C-terminal region in fibroblast cell adhesion

Fibroblast adhesion can be modulated by proteins released by neuroendocrine cells and neurons, such as chromogranin A (CgA) and its N-terminal fragment vasostatin-1 (VS-1, CgA(1-78)). We have investigated the mechanisms of the interaction of VS-1 with fibroblasts and of its pro-adhesive activity and have found that the proadhesive activity of VS-1 relies on its interaction with the fibroblast membrane via a phospholipid-binding amphipathic alpha-helix located within residues 47-66, as well as on the interaction of the adjacent C-terminal region 67-78, which is structurally similar to ezrin-radixin-moesin-binding phosphoprotein 50 (a membrane-cytoskeleton adapter protein), with other cellular components critical for the regulation of cell cytoskeleton.

Gut hormones: emerging role in immune activation and inflammation

Gut inflammation is characterized by mucosal recruitment of activated cells from both the innate and adaptive immune systems. In addition to immune cells, inflammation in the gut is associated with an alteration in enteric endocrine cells and various biologically active compounds produced by these cells. Although the change in enteric endocrine cells or their products is considered to be important in regulating gut physiology (motility and secretion), it is not clear whether the change plays any role in immune activation and in the regulation of gut inflammation. Due to the strategic location of enteric endocrine cells in gut mucosa, these gut hormones may play an important role in immune activation and promotion of inflammation in the gut. This review addresses the research on the interface between immune and endocrine systems in gastrointestinal (GI) pathophysiology, specifically in the context of two major products of enteric endocrine systems, namely serotonin (5-hydroxytryptamine: 5-HT) and chromogranins (Cgs), in relation to immune activation and generation of inflammation. The studies reviewed in this paper demonstrate that 5-HT activates the immune cells to produce proinflammatory mediators and by manipulating the 5-HT system it is possible to modulate gut inflammation. In the case of Cgs the scenario is more complex, as this hormone has been shown to play both proinflammatory and anti-inflammatory functions. It is also possible that interaction between 5-HT and Cgs may play a role in the modulation of immune and inflammatory responses. In addition to enhancing our understanding of immunoendocrine interaction in the gut, the data generated from the these studies may have implications in understanding the role of gut hormone in the pathogenesis of both GI and non-GI inflammatory diseases which may lead ultimately to improved therapeutic strategies in inflammatory disorders.

Plasma chromogranin a in patients with inflammatory bowel disease

BACKGROUND

Circulating chromogranin A (CgA) levels, a marker for neuroendocrine tumors including carcinoids, have recently been found elevated in some patients with inflammatory bowel disease (IBD), although their significance is unclear. Therefore, we aimed to evaluate CgA levels and their possible relationship with clinical and biochemical disease activity indexes in 119 IBD patients.

METHODS

The study groups comprised 75 patients with ulcerative colitis, 44 with Crohn's disease, in both active and quiescent phases, and 85 controls.

RESULTS

Mean CgA levels were significantly higher in IBD patients than in controls (20.4 +/- 14.0 [SD] versus 11.3 +/- 4.3 U/L, P < 0.001), without any statistical significant difference among the IBD subgroups. However, CgA levels were above the normal range (20 U/L) in 25/45 patients with active IBD (55%; 95% confidence interval [CI]: 40%-70%) and in 18/74 patients with remission IBD (24%; 95% CI: 15%-36%) (P < 0.001, Fisher's test). Among biochemical parameters, CgA correlated with serum TNF-alpha levels (r(s) = 0.398, P < 0.001).

CONCLUSIONS

High CgA levels can occur in IBD. The disease activity and TNF-alpha levels seem to influence the CgA pattern, which could reflect the neuroendocrine system activation in response to inflammation. From a clinical point of view, the possibility of high CgA levels in IBD should be taken into consideration when a carcinoid is suspected in such patients, since this event seems to be more frequent than previously considered. Indeed, revision of our 83 patients with gastrointestinal carcinoids, studied between 1997 and 2006, showed that 4 patients had IBD, with a prevalence of 4.8%, which is markedly higher than that of the general population.

Prognostic value of circulating chromogranin A levels in acute coronary syndromes

AIMS

To determine whether circulating levels of chromogranin A (CgA) provide prognostic information independently of conventional risk markers in acute coronary syndromes (ACSs).

METHODS AND RESULTS

We measured circulating CgA levels on day 1 in 1268 patients (median age 67 years, 70% male) with ACS admitted to a single coronary care unit of a Scandinavian teaching hospital. The merit of CgA as a biomarker was evaluated after adjusting for conventional cardiovascular risk factors. During a median follow-up of 92 months, 389 patients (31%) died. The baseline CgA concentration was strongly associated with increased long-term mortality [hazard ratio per 1 standard deviation increase in logarithmically transformed CgA level: 1.57 (1.44-1.70), P < 0.001], heart failure hospitalizations [1.54 (1.35-1.76), P < 0.001], and recurrent myocardial infarction (MI) [1.27 (1.10-1.47), P < 0.001], but not stroke. After adjustment for conventional cardiovascular risk markers, the association remained significant for mortality [hazard ratio 1.28 (1.15-1.42), P < 0.001] and heart failure hospitalization [hazard ratio 1.24 (1.04-1.47), P = 0.02], but not recurrent MI.

CONCLUSION

CgA is an independent predictor of long-term mortality and heart failure hospitalizations across the spectrum of ACSs and provides incremental prognostic information to conventional cardiovascular risk markers.

Conversation galante: how the immune and the neuroendocrine systems talk to each other

The generation of endogenous adjuvants and the clearance of apoptotic cells occur at the intersection between the neuroendocrine and the immune systems. Recent data suggest that autoimmunity associates with a communication breakdown between the two systems and that events taking place in lymphoid organs and in peripheral inflamed tissues shape the response to tissue damage. Autonomic nerve endings release norepinephrine and acetylcholine, whereas sensitive fibers release neuropeptides. Moreover, nervous endings in the tissues control the secretory activity of neuroendocrine cells, which are distributed in the gut, the pancreas, the lung, the thyroid, the liver, the prostate, the skin. Intracellular enzymes, and in particular the 11 beta-hydroxysteroid dehydrogenase type 1, regulate the availability of active glucocorticoids in inflammatory macrophages and maturing dendritic cells; in turn the rate of active glucocorticoids determine the efficiency of phagocytes in clearing apoptotic cells, possibly influencing the availability of autoantigens. Immune cells release cytokines, which, in turn signal to the central and peripheral nervous system. We learnt from cytokine-neutralizing therapies that the sustained production of pro-inflammatory signals interferes with various neuro-endocrine axes. A better molecular dissection of this finely regulated inter-system cross-talk, in physiological conditions and during self-sustaining inflammatory diseases, might enable more rational therapeutic approaches.

Prognostic value of plasma chromogranin A levels in patients with complicated myocardial infarction

BACKGROUND

Chromogranin A is widely distributed throughout the neuroendocrine system and may, because of its long in vivo and in vitro half-life, be an attractive candidate for assessment of overall neuroendocrine activity. Recently, increased plasma levels of chromogranin A have been found in patients with chronic heart failure and related to the severity of symptoms and prognosis. The objective of the current study was to assess the prognostic value of chromogranin A levels after complicated myocardial infarction.

METHODS

We assessed the association between plasma chromogranin A levels obtained in the hospitalization phase and time to hospitalization for heart failure or death in 217 patients with complicated myocardial infarction included in the OPTIMAAL trial.

RESULTS

During a median follow-up time of 1017 days, there were 44 first events (30 deaths and 14 hospitalizations for congestive heart failure). Logarithmically transformed chromogranin A (P < .001) and N-terminal pro-B-type natriuretic peptide (P = .001), patient age (P < .001), estimated creatinine clearance (P < .001), a history of myocardial infarction or angina (P = .001), and diabetes mellitus (P = .011), using univariable Cox proportional hazards regression, were significantly associated with outcome, whereas sex, randomization status, history of hypertension, C-reactive protein, and the presence of inhospital heart failure were not. In a multivariable model, logarithmically transformed chromogranin A (P = .002), patient age (P < .0001), history of diabetes (P = .004), and male sex (P = .021) were independently predictive of outcome.

CONCLUSION

Chromogranin A is a strong and independent prognostic indicator in patients with complicated myocardial infarction.

Neuroendocrine Modulation Induced by Selective Blockade of TNF- in Rheumatoid Arthritis

Tumor necrosis factor-alpha (TNFalpha) is a main actor in the pathogenesis of rheumatoid arthritis (RA), interacting with other molecules in complex mechanisms. The neuroendocrine system is known to be involved and Chromogranin A (CHGA) serum levels are elevated in patients with RA. We evaluated the effect of the selective blockade of TNF-alpha, induced by treatment with anti-TNF-alpha monoclonal antibodies (mAbs), on the serum levels of CHGA and on its correlation with TNF-alpha and TNF-alpha receptors (TNFRs) serum levels. Seven patients with RA have been treated with the anti-TNF-alpha mAb, infliximab. We measured the serum levels of TNF-alpha, its receptors (tumor necrosis factor receptor-I [TNFR-I] and tumor necrosis factor receptor-II [TNFR-II]), and CHGA before and during the treatment. We also measured, as a control, the serum levels of CHGA, TNF-alpha, and soluble TNFRs in 14 patients who were being treated with infliximab, adalimumab, or etanercept and in 20 matching negative controls. The serum levels of TNFR-I and TNFR-II, which are a sensitive marker for the TNF-alpha pathway, correlated with those of CHGA before treatment (Pearson's coefficient, respectively, 0.59 and 0.53). Treatment with anti-TNF-alpha mAb provided a significant clinical response in all patients and the correlation between CHGA and TNFR-I and TNFR-II was no more evident during treatment (respectively, -0.09 and -0.07). TNF-alpha blockade allows a clinical effect in patients with RA and modifies the correlation between CHGA and TNFRs, suggesting that TNF-alpha and CHGA reciprocally interfere in the pathogenesis of RA, through intermediate adaptors, whose identification warrants further studies.

The granin family of uniquely acidic proteins of the diffuse neuroendocrine system: comparative and functional aspects

The chromogranins A (CgA) and B (CgB) and secretogranin II (SgII) constitute the main members of a family of uniquely acidic secretory proteins in elements of the diffuse neuroendocrine system. These genetically distinct proteins, CgA, CgB, SgII and the less well known secretogranins III-VII are collectively referred to as 'granins' and characterised by numerous pairs of basic amino acids as potential cleavage sites for processing by the co-stored prohormone converting enzymes PC 1/3 and PC2. This review is directed towards comparative and functional aspects of the granins with emphasis on their phylogenetically conserved sequences. Recent developments provide ample evidence of widely different effects and targets for the intact granins and their derived peptides, intracellularly in the directed trafficking of storage components during granule maturation and extracellularly in autocrine, paracrine and endocrine interactions. Most of the effects assigned to the granin derived peptides fit into patterns of direct or indirect inhibitory modulations of major functions. So far, peptides derived from CgA (vasostatins, chromacin, pancreastatin, WE-14, catestatin and parastatin), CgB (secretolytin) and SgII (secretoneurin) are the most likely candidates for granin-derived regulatory peptides, of postulated relevance not only for homeostatic processes, but also for tissue assembly and repair, inflammatory responses and the first line of defence against invading microorganisms.

Expression of amino acid sequences of the chromogranin A molecule and synaptic vesicle protein 2 in neuroendocrine tumors of the lung

Chromogranin A (CgA) and its valuable complement synaptic vesicle protein 2 (SV2) are neuroendocrine (NE) markers. Post-translational processing of CgA has been reported to vary in different NE cell types and tumors, but little is known regarding the expression of various CgA epitopes and SV2 in NE pulmonary tumors. We studied the immunoreactivity to six CgA epitopes and SV2 in ten typical (TC) and ten atypical (ACT) carcinoids, five large-cell NE carcinomas (LCNEC) and five small-cell carcinomas (SCLC), also comparing the results with clinicopathological characteristics of tumors. The sequences CgA 17--38 (vasostatin), 176--195 (chromacin), 375--384 (parastatin) and 411--424 (C-terminal parastatin) and SV2 were relevant markers for the CT/ATC group, whereas the antibody to CgA 176--195 was a better marker for the LCNEC/SCLC group. An inverse correlation was found between proliferative activity and granule-related markers in the CT/ACT group, and a direct correlation in poorly differentiated tumors. The expression of granule-related markers did not correlate with hormone content or clinical characteristics of NE tumors. The expression of CgA epitopes and SV2 occurs in all NE tumors, differing between better differentiated and poorly differentiated tumors but not within the respective groups.

Inhibition of tumor growth by intramuscular injection of cDNA encoding tumor necrosis factor alpha coupled to NGR and RGD tumor-homing peptides

The antitumor properties of tumor necrosis factor alpha (TNF) and its efficacy in selective destruction of tumor-associated vessels are well known. Besides the TNF protein, the TNF gene has been used for gene therapy of cancer and shown to induce antitumor responses both in animal models and in patients. We show here that the therapeutic properties of the TNF gene are improved by fusing the TNF sequence with those of peptides able to target tumor vessels, such as CNGRCG or ACDCRGDCFCG. Intramuscular administration of plasmid DNA encoding CNGRCG-TNF and ACDCRGDCFCG-TNF (pNGR-TNF and pRGD-TNF, respectively), but not plasmids encoding TNF (pTNF) or empty vector (pMock), inhibited the growth of subcutaneous murine B16F1 melanomas and RMA-T lymphomas implanted at sites distant from the site of plasmid injection. The combination of pNGR-TNF or pRGD-TNF with doxorubicin or melphalan induced stronger effects than single agents. These treatments induced antitumor effects without activating toxic or negative feedback mechanisms. In addition, pRGD-TNF increased the uptake of an antibody directed to a tumor-associated antigen. These results suggest that the therapeutic properties of NGR-TNF and RGD-TNF cDNAs are greater than those of TNF cDNA and provide the rationale for developing new gene therapy approaches based on vascular targeting with TNF coupled to tumor-homing peptides.

Chromogranin A protects vessels against tumor necrosis factor alpha-induced vascular leakage

Elevated levels of circulating chromogranin A (CgA), a protein stored in the secretory granules of many neuroendocrine cells and neurons, have been detected in the blood of patients with neuroendocrine tumors or heart failure. The pathophysiological role of increased secretion of CgA is unknown. Using mice bearing subcutaneous tumors genetically engineered to secrete CgA in circulation, we have found that increased blood levels of this protein prevent vascular leakage induced by tumor necrosis factor-alpha (TNF) in the liver venous system. Structure-activity studies, carried out with CgA fragments administered to normal mice, showed that an active site is located within residues 7-57 of CgA. Accordingly, an anti-CgA antibody directed to residues 53-57 inhibited the effect of circulating CgA, either endogenously produced or exogenously administered, on liver vessels. Studies of the mechanism of action showed that CgA inhibits TNF-induced VE-cadherin down-regulation and barrier alteration of cultured endothelial cells, in an indirect manner. Other effectors, such as thrombin and vascular endothelial growth factor were partially inhibited by CgA N-terminal fragments in in vitro permeability assays. These findings suggest that circulating CgA could help regulate the endothelial barrier function and to protect vessels against TNF-induced plasma leakage in pathological conditions characterized by increased production of TNF and CgA, such as cancer or heart failure.

Targets for pharmacological intervention of endothelial hyperpermeability and barrier function

Many diseases share the common feature of vascular leakage, and endothelial barrier dysfunction is often the underlying cause. The subsequent stages of endothelial barrier dysfunction contribute to endothelial hyperpermeability. Vasoactive agents induce loss of junctional integrity, a process that involves actin-myosin interaction. Subsequently, the interaction of leukocytes amplifies leakage by the leukocyte-derived mediators. The processes mainly occur at the postcapillary venules. The whole microvascular bed, including the capillaries, becomes involved in vascular leakage by the induction of angiogenesis. Plasma leakage results from gaps between endothelial cells as well as by the induction of transcellular transport pathways. Several mechanisms can improve endothelial barrier function, depending on the tissue affected and the cause of hyperpermeability. They include blockade of specific receptors and elevation of cyclic AMP (cAMP) by agents such as beta(2)-adrenergic agents. However, current therapies based on these principles often fail. Recent research has identified several new promising targets for pharmacological therapy. Endogenous compounds were also found with barrier-improving characteristics. Important insights were obtained in the different pathways involved in barrier dysfunction. Such insights regard the regulation of endothelial contraction and endothelial junction integrity: inhibitors of RhoA activation and Rho kinase represent a potentially valuable group of agents with endothelial hyperpermeability reducing properties, and strategies to target vascular endothelial growth factor (VEGF)-mediated edema are under current investigation. In clinical practice, not only tools to improve an impaired endothelial barrier function are necessary. Sometimes, a controlled, temporal, and local increase in permeability can also be desired, for example, with the aim to enhance drug delivery. Therefore, vessel leakiness is also being exploited to enable tissue access of liposomes, viral vectors, and other therapeutic agents that do not readily cross healthy endothelium. This review discusses strategies for targeting signaling molecules in therapies for diseases involving altered endothelial permeability.