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GDNF protects enteric glia from apoptosis: evidence for an autocrine loop.

Steinkamp M, Gundel H, Schulte N, Spaniol U, Pflueger C, Zizer E, von Boyen GB - BMC Gastroenterol (2012)

Bottom Line: Increased GDNF expression and Caspase 3/7 activities were detected in in specimen of CD patients but not in healthy controls.Moreover, inactivation of GDNF sensitized in EGC cell to IFN-γ/TNF-α induced apoptosis.Alterations in this novel EGC self-protecting mechanism could lead to a higher susceptibility towards apoptosis and thus contribute to disruption of the mucosal integrity and severity of inflammation in CD.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Gastroenterology, Endocrinology and Metabolism, University of Giessen und Marburg GmbH, Site Marburg, Baldingerstrasse, 35037 Marburg, Germany.

ABSTRACT

Background: Enteric glia cells (EGC) play an important role in the maintenance of intestinal mucosa integrity. During the course of acute Crohn's disease (CD), mucosal EGC progressively undergo apoptosis, though the mechanisms are largely unknown. We investigated the role of Glial-derived neurotrophic factor (GDNF) in the regulation of EGC apoptosis.

Methods: GDNF expression and EGC apoptosis were determined by immunofluorescence using specimen from CD patients. In primary rat EGC cultures, GDNF receptors were assessed by western blot and indirect immunofluorescence microscopy. Apoptosis in cultured EGC was induced by TNF-α and IFN-γ, and the influence of GDNF on apoptosis was measured upon addition of GDNF or neutralizing anti-GDNF antibody.

Results: Increased GDNF expression and Caspase 3/7 activities were detected in in specimen of CD patients but not in healthy controls. Moreover, inactivation of GDNF sensitized in EGC cell to IFN-γ/TNF-α induced apoptosis.

Conclusions: This study proposes the existence of an autocrine anti-apoptotic loop in EGC cells which is operative in Crohn's disease and dependent of GDNF. Alterations in this novel EGC self-protecting mechanism could lead to a higher susceptibility towards apoptosis and thus contribute to disruption of the mucosal integrity and severity of inflammation in CD.

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Biopsies of the inflamed colon of patients suffering from CD and controls were double immunolabelled with anti GFAP (A,D,G,J red) and cCaspase-3 (B,E green) or anti GDNF (H,K green) antibodies and were analyzed by optical sectioning using a confocal microscope. Both antigens, GFAP (A) and c-Caspase-3 (B) can be detected highly in the intestinal wall of the inflamed colon of CD (A,B). The merged images (C) reveal an almost complete overlap of both immunoreactivities (yellow). Only few GFAP-positive cells (D) display no cCaspase-3 immunoreactivity (E) in the control section (F). Although a high immunoreactivity of GDNF (H) in GFAP-positive cells (G,I) and in the epithelial cells of biopsies of patients with CD can be detected, in control biopsies GFAP-positive EGCs (J), which are positioned in the mucosal plexus in close vicinity to the epithelium of the colon, show no GDNF secretion (K,L). Furthermore the subepithelial cells, which express GDNF highly (N, green) showed a colocalization with cCaspase-3 in sections of CD (M-O), whereas in controls no relevant apotosis, proofed by cCaspase-3, or GDNF expression could be detected (P-R). Scale bars, 50 um.
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Figure 1: Biopsies of the inflamed colon of patients suffering from CD and controls were double immunolabelled with anti GFAP (A,D,G,J red) and cCaspase-3 (B,E green) or anti GDNF (H,K green) antibodies and were analyzed by optical sectioning using a confocal microscope. Both antigens, GFAP (A) and c-Caspase-3 (B) can be detected highly in the intestinal wall of the inflamed colon of CD (A,B). The merged images (C) reveal an almost complete overlap of both immunoreactivities (yellow). Only few GFAP-positive cells (D) display no cCaspase-3 immunoreactivity (E) in the control section (F). Although a high immunoreactivity of GDNF (H) in GFAP-positive cells (G,I) and in the epithelial cells of biopsies of patients with CD can be detected, in control biopsies GFAP-positive EGCs (J), which are positioned in the mucosal plexus in close vicinity to the epithelium of the colon, show no GDNF secretion (K,L). Furthermore the subepithelial cells, which express GDNF highly (N, green) showed a colocalization with cCaspase-3 in sections of CD (M-O), whereas in controls no relevant apotosis, proofed by cCaspase-3, or GDNF expression could be detected (P-R). Scale bars, 50 um.

Mentions: In biopsy specimen of patients suffering from CD, caspase 3 activation could be detected in the mucosal glial plexus, and this was coincident to GFAP and to GDNF expression in the same structures. In controls, neither caspase 3 activation nor GFAP or GNDF upregulation was recognized (Figure 1). These results suggest the occurence of apoptosis in the mucosal plexus and GDNF upregulation in the context of chronic bowel inflammation.


GDNF protects enteric glia from apoptosis: evidence for an autocrine loop.

Steinkamp M, Gundel H, Schulte N, Spaniol U, Pflueger C, Zizer E, von Boyen GB - BMC Gastroenterol (2012)

Biopsies of the inflamed colon of patients suffering from CD and controls were double immunolabelled with anti GFAP (A,D,G,J red) and cCaspase-3 (B,E green) or anti GDNF (H,K green) antibodies and were analyzed by optical sectioning using a confocal microscope. Both antigens, GFAP (A) and c-Caspase-3 (B) can be detected highly in the intestinal wall of the inflamed colon of CD (A,B). The merged images (C) reveal an almost complete overlap of both immunoreactivities (yellow). Only few GFAP-positive cells (D) display no cCaspase-3 immunoreactivity (E) in the control section (F). Although a high immunoreactivity of GDNF (H) in GFAP-positive cells (G,I) and in the epithelial cells of biopsies of patients with CD can be detected, in control biopsies GFAP-positive EGCs (J), which are positioned in the mucosal plexus in close vicinity to the epithelium of the colon, show no GDNF secretion (K,L). Furthermore the subepithelial cells, which express GDNF highly (N, green) showed a colocalization with cCaspase-3 in sections of CD (M-O), whereas in controls no relevant apotosis, proofed by cCaspase-3, or GDNF expression could be detected (P-R). Scale bars, 50 um.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3298702&req=5

Figure 1: Biopsies of the inflamed colon of patients suffering from CD and controls were double immunolabelled with anti GFAP (A,D,G,J red) and cCaspase-3 (B,E green) or anti GDNF (H,K green) antibodies and were analyzed by optical sectioning using a confocal microscope. Both antigens, GFAP (A) and c-Caspase-3 (B) can be detected highly in the intestinal wall of the inflamed colon of CD (A,B). The merged images (C) reveal an almost complete overlap of both immunoreactivities (yellow). Only few GFAP-positive cells (D) display no cCaspase-3 immunoreactivity (E) in the control section (F). Although a high immunoreactivity of GDNF (H) in GFAP-positive cells (G,I) and in the epithelial cells of biopsies of patients with CD can be detected, in control biopsies GFAP-positive EGCs (J), which are positioned in the mucosal plexus in close vicinity to the epithelium of the colon, show no GDNF secretion (K,L). Furthermore the subepithelial cells, which express GDNF highly (N, green) showed a colocalization with cCaspase-3 in sections of CD (M-O), whereas in controls no relevant apotosis, proofed by cCaspase-3, or GDNF expression could be detected (P-R). Scale bars, 50 um.
Mentions: In biopsy specimen of patients suffering from CD, caspase 3 activation could be detected in the mucosal glial plexus, and this was coincident to GFAP and to GDNF expression in the same structures. In controls, neither caspase 3 activation nor GFAP or GNDF upregulation was recognized (Figure 1). These results suggest the occurence of apoptosis in the mucosal plexus and GDNF upregulation in the context of chronic bowel inflammation.

Bottom Line: Increased GDNF expression and Caspase 3/7 activities were detected in in specimen of CD patients but not in healthy controls.Moreover, inactivation of GDNF sensitized in EGC cell to IFN-γ/TNF-α induced apoptosis.Alterations in this novel EGC self-protecting mechanism could lead to a higher susceptibility towards apoptosis and thus contribute to disruption of the mucosal integrity and severity of inflammation in CD.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Gastroenterology, Endocrinology and Metabolism, University of Giessen und Marburg GmbH, Site Marburg, Baldingerstrasse, 35037 Marburg, Germany.

ABSTRACT

Background: Enteric glia cells (EGC) play an important role in the maintenance of intestinal mucosa integrity. During the course of acute Crohn's disease (CD), mucosal EGC progressively undergo apoptosis, though the mechanisms are largely unknown. We investigated the role of Glial-derived neurotrophic factor (GDNF) in the regulation of EGC apoptosis.

Methods: GDNF expression and EGC apoptosis were determined by immunofluorescence using specimen from CD patients. In primary rat EGC cultures, GDNF receptors were assessed by western blot and indirect immunofluorescence microscopy. Apoptosis in cultured EGC was induced by TNF-α and IFN-γ, and the influence of GDNF on apoptosis was measured upon addition of GDNF or neutralizing anti-GDNF antibody.

Results: Increased GDNF expression and Caspase 3/7 activities were detected in in specimen of CD patients but not in healthy controls. Moreover, inactivation of GDNF sensitized in EGC cell to IFN-γ/TNF-α induced apoptosis.

Conclusions: This study proposes the existence of an autocrine anti-apoptotic loop in EGC cells which is operative in Crohn's disease and dependent of GDNF. Alterations in this novel EGC self-protecting mechanism could lead to a higher susceptibility towards apoptosis and thus contribute to disruption of the mucosal integrity and severity of inflammation in CD.

Show MeSH
Related in: MedlinePlus