Chromogranin A (CGA) and the enterochromaffin-like (ECL) cell

Chromogranin-A Regulates Macrophage Function and the Apoptotic Pathway in Murine DSS colitis

Chromogranin-A (CHGA) is elevated in inflammatory bowel disease (IBD), but little is known about its role in colonic inflammation. IBD is associated with impaired functions of macrophages and increased apoptosis of intestinal epithelial cells. We investigated CHGA expression in human subjects with active ulcerative colitis (UC) and the underlying mechanisms in Chga ^-/- mice. In UC, CHGA, classically activated macrophage (M1) markers, caspase-3, p53, and its associated genes were increased, while alternatively activated macrophage (M2) markers were decreased without changes in the extrinsic apoptotic pathway. CHGA correlated positively with M1 and the apoptotic pathway and negatively with M2. In the murine dextran sulfate sodium (DSS)-induced colitis, Chga deletion reduced the disease severity and onset, pro-inflammatory mediators, M1, and p53/caspase-3 activation, while it upregulated anti-inflammatory cytokines and M2 markers with no changes in the extrinsic apoptotic markers. Compared to Chga ^+/+ , M1 and p53/caspase-3 activation in Chga ^-/- macrophages were decreased in vitro, while M2 markers were increased. CHGA plays a critical role during colitis through the modulation of macrophage functions via the caspase-3/p53 pathway. Strategies targeting CHGA to regulate macrophage activation and apoptosis might be developed to treat UC patients.

KEY MESSAGES

• Chromogranin-A (CHGA) is pro-hormone and is secreted in the gut. CHGA is elevated in colitis and is associated with the disease severity. The lack of GHGA has beneficial immunomodulatory properties during the development of intestinal inflammation. The lack of CHGA regulates the plasticity of macrophages and p53/caspase activation in colitis. Functional analysis of CHGA may lead to a novel therapy for IBD.

Catestatin decreases macrophage function in two mouse models of experimental colitis

Mucosal inflammation in patients with inflammatory bowel disease (IBD) is characterized by an alteration of prohormone chromogranin A (CgA) production. The recent demonstration of an implication of CgA in collagenous colitis and immune regulation provides a potential link between CgA-derived peptides (catestatin, CTS) and gut inflammation. Colitis was induced by administration of dextran sulfate sodium or 2, 4 dinitrobenzenesulfonic acid to C57BL/6 mice. Treatment with human (h)CTS or its proximal or distal part was started one day before colitis induction and colonic inflammatory markers were determined. Pro-inflammatory cytokines were evaluated in peritoneal isolated and bone marrow derived macrophages (BMDMs); p-STAT3 level was studied. Serum levels of CgA and CTS were assessed in experimental colitis and in a separate study in IBD patients and healthy controls. We show that sera from IBD patients and that in experimental colitis conditions the colonic level of mouse (m)CgA and mCTS are significantly increased. Moreover, in vivo treatment with human (h)CTS reduces the disease onset and suppresses exacerbated inflammatory responses in preclinical settings of colitis associated with an increase of p-STAT3. In vitro, hCTS treatment decreases proinflammatory cytokine release by peritoneal macrophages and BMDMs and increases p-STAT3 levels. These results support the hypothesis that CTS is increased during colitis and that hCTS modulates intestinal inflammation via the macrophage population and through a STAT-3 dependent pathway in a murine model of colitis. Identification of the molecular mechanism underlying the protective role of this peptide may lead to a novel therapeutic option in IBD.

Five-year follow-up of patients treated for 1 year with octreotide long-acting release for enterochromaffin-like cell carcinoids

BACKGROUND

Gastric carcinoids type 1 (GC1) are neuroendocrine tumors (NETs) arising from the enterochromaffin-like (ECL) cells in patients with chronic atrophic gastritis (CAG). The treatment of GC1 has been endoscopic polypectomy or surgical tumor excision and antrectomy. One year treatment with somatostatin analogs (SSAs) diminished tumor load and ECL cell density. The effect persisted 1 year after treatment was discontinued. However, the optimal SSA dose and treatment duration are unknown.

OBJECTIVES

The aim of the present work was to study macroscopic and histopathological changes in the stomach and serum markers gastrin and chromogranin A (CgA) in GC1 patients 5 years after 1 year of octreotide long-acting release (LAR) treatment.

MATERIAL AND METHODS

Five patients with GC1 were included 5 years after the initial year of octreotide LAR treatment. All patients underwent upper gastrointestinal endoscopy including tumor and mucosal biopsies from oxyntic mucosa, chest and abdominal computer tomography and octreotide scintigraphy. Fasting serum gastrin and CgA were also measured.

RESULTS

At 5 years, one patient had a highly malignant gastric tumor, one patient had an increased number of GCs, regional and distant metastases and three patients had an increased number of GCs. Serum gastrin and CgA increased to pre-treatment levels after 1 year of follow-up and were unchanged at the 5-year follow-up.

CONCLUSIONS

The disease had progressed in all five GCs patients treated with octreotide for 12 months at 5 years of follow-up. This suggests that, if started, octreotide treatment should not be discontinued in these patients.

One-year follow-up study of patients with enterochromaffin-like cell carcinoids after treatment with octreotide long-acting release

OBJECTIVE

In a one-year study of 5 patients with chronic atrophic gastritis (CAG), pernicious anaemia (PA), hypergastrinaemia and enterochromaffin-like (ECL) cell tumours, the somatostatin analogue octreotide LAR (long-acting release) in a dose of 20 mg given intramuscularly at monthly intervals had an antiproliferative effect on the ECL cells. The aim of the present study was to follow neuroendocrine (NE) markers in the blood and macroscopic and histopathological changes in the stomach during a 12-month follow-up after discontinuation of octreotide LAR treatment.

MATERIAL AND METHODS

Five patients underwent upper gastrointestinal endoscopy at 6 and 12 months' follow-up after octreotide LAR treatment. Biopsies from flat, oxyntic mucosa and from tumours were obtained. Sections were stained with haematoxylin-erythrosin and immunostained for the NE cell marker chromogranin A (CgA). Serum gastrin and CgA were measured every 3 months.

RESULTS

The number of visible tumours was unchanged (7) at 12 months' follow-up. One lesion showed carcinoid tumour and the others various degrees of linear and micronodular NE hyperplasia. At the same time-point, biopsies from flat, oxyntic mucosa showed a slightly (non-significant) elevated number of CgA immunoreactive (IR) cells. Serum gastrin increased from 186+/-50 pM (mean+/-SEM) to 603+/-109 pM (normal < 40 pM); p<0.05, and serum CgA increased non-significantly from 25+/-2 ng/ml (normal < 30 ng/ml) to 61+/-11 ng/ml.

CONCLUSIONS

During follow-up, slightly elevated levels of serum CgA and CgA IR cells in the oxyntic mucosa, without significant recurrence of ECL cell carcinoids, were observed.

Effects of a chromogranin-derived peptide (CgA 47-66) in the writhing nociceptive response induced by acetic acid in rats

Chromogranin A (CgA) is an acidic protein identified within a large variety of endocrine cells. Colocalized with catecholamines in chromaffin cells, CgA is a prohormone precursor of small biologically active peptides. Vasostatin (CgA 1-76) is the most conserved fragment of CgA and chromogranin A 47-66 peptide (CgA 47-66) possesses potent antimicrobial activities. The aim of this study was to test the hypothesis that CgA 47-66 may be involved in mechanisms modulating nociception. Thus, we used acetic acid (AA) which produces a delayed inflammatory response and episodes of abdominal writhing, a marker of pain, when injected intraperitoneally (i.p.) to rats. Administration (i.p.) of CgA 47-66 induced specific opposite dose-dependent effects depending on concentration. That is, CgA 47-66 below 0.5 mg/kg produced antinociceptive effects, whereas at 2 mg/kg it produced a marked pronociceptive effect. The latter effect was blocked by diltiazem and indomethacin. CgA 47-66-induced antinociceptive effects on AA-induced responses were reversed when the corticotropin-releasing factor (CRF) antagonist alpha-helical CRF 9-41 was i.p. injected to animals prior to AA and CgA 47-66 administration. The administration of i.p. calcitonin gene-related peptide (CGRP) or substance P (SP) evoked dose-dependent abdominal writhing; this effect was abolished when CgA 47-66 was injected. The present data suggest, for the first time, that a fragment of CgA, CgA 47-66, possesses potent antinociceptive effects at low doses. Although the mechanism triggered by this peptide is unknown, CRF receptors are likely to be involved.

Treatment of ECL cell carcinoids with octreotide LAR

BACKGROUND

Patients with chronic atrophic gastritis (CAG) and hypergastrinaemia are at risk of developing hyperplasia of the enterochromaffin-like (ECL) cells and ECL-cell-derived tumours. The effect of the somatostatin analogue octreotide on ECL cell carcinoids is examined.

METHODS

Five patients with hypergastrinaemia and ECL cell carcinoids were enrolled in a 1-year study of octreotide LAR (long-acting release) 20 mg given at monthly intervals. Biopsies from tumours and from flat oxyntic mucosa were done at the start and 3, 6 and 12 months thereafter. Sections were stained with haematoxylin-erythrosin, immunostained with chromogranin A (CgA) and doublestained with CgA and Ki-67. Serum gastrin and CgA were measured.

RESULTS

The number of visible tumours was reduced by more than 50 %. Sections from both tumours and flat mucosa showed a reduced number of CgA immunoreactive cells. Mean serum gastrin decreased from 421 to 186 pM (normal <40 pM); P > 0.05, and serum CgA from 73 to 25 ng/ml (normal < 30 ng/ml); P < 0.001.

CONCLUSIONS

During treatment the patients were still markedly hypergastrinaemic, whereas the serum CgA showed normalization. A diminished tumour load and reduced ECL cell density were found, indicating an antiproliferative effect of octreotide directly on the ECL cells.

Interest of Chromogranin A for diagnosis and follow-up of endocrine tumours

OBJECTIVE

To determine the interest of Chromogranin A (CgA) determination for diagnosis and follow-up in patients with gastroenteropancreatic endocrine tumours (GEP-ET) and multiple endocrine neoplasia type 1 (MEN-1).

PATIENTS AND METHODS

CgA levels were measured with an immunoradiometric assay in 124 sporadic GEP-ET, 34 MEN-1 and 127 controls. Serial determinations were performed in 56 patients (212 visits). Changes in CgA levels over 25% were considered as significant.

RESULTS

Using a cut-off value of 130 micro g/l, established from a receiver-operating characteristic curve, the specificity of CgA was 98.4%, with a sensitivity of 62.9%, higher in secreting than in nonsecreting tumours (73%vs. 45%; P < 0.003) and related to the extent of metastatic spreading (P < 0.001). In nonsecreting tumours, the positive predictive value (PPV) of CgA for the presence of metastases was 100% but the negative predictive value (NPV) was only 50%. In MEN-1, high CgA levels indicated a pancreatic tumour with a 100% specificity but the sensitivity was 59%. During the follow-up, the concordance between CgA and tumour evolution was 80%, whatever the secretory status. In patients with carcinoid tumours, the concordance was higher for CgA than for serotonin (81%vs. 54%; P < 0.001).

CONCLUSION

Due to its high specificity, CgA determination may help to discriminate the endocrine character of a GEP tumour and to indicate a pancreatic tumour in MEN-1. However, its low NPV in nonsecreting tumours limits its interest for diagnosis and staging. By contrast, serial evaluation of CgA seems of particular interest for the follow-up of GEP-ET tumours.

Prospective study of the ability of histamine, serotonin or serum chromogranin A levels to identify gastric carcinoids in patients with gastrinomas

BACKGROUND

Chronic hypergastrinaemia causes gastric enterochromaffin cell proliferation and carcinoid tumours. The only reliable means to diagnose enterochromaffin cell changes/carcinoids is by biopsy.

AIM

To assess whether serum histamine, chromogranin A or serotonin and urinary N-methylimidazoleacetic acid or 5-hydroxyindoleacetic acid correlate with advanced enterochromaffin cell changes or gastric carcinoids in patients with gastrinomas.

METHODS

Consecutive patients (n=145) had the above assays and endoscopy with gastric biopsies.

RESULTS

Lower N-methylimidazoleacetic acid and chromogranin A levels (P < 0.0001) occurred in disease-free patients. In patients with active disease, the fasting serum gastrin levels correlated (P < 0.0001) with both chromogranin A and N-methylimidazoleacetic acid levels. Chromogranin A (P=0.005), but not N-methylimidazoleacetic acid, serotonin, 5-hydroxyindoleacetic acid or histamine levels, correlated with the enterochromaffin cell index. Carcinoids, but not advanced enterochromaffin cell changes only, were associated with higher chromogranin A and N-methylimidazoleacetic acid levels.

CONCLUSIONS

Serum chromogranin A levels and urinary N-methylimidazoleacetic acid levels, but not serum histamine or serotonin or urinary 5-hydroxyindoleacetic acid, correlate with the presence of gastric carcinoids. However, no assay identified patients with advanced enterochromaffin cell changes only with high sensitivity/specificity. Thus, N-methylimidazoleacetic acid and chromogranin A levels are unable to identify patients with advanced changes in enterochromaffin cells and therefore neither can replace routine gastric biopsies.