Phosphatidylserine receptor in chronic pancreatitis: evidence for a macrophage independent role.
OBJECTIVE
This study analyzes the role of phosphatidylserine receptor (PSR) in chronic pancreatitis.


BACKGROUND
In chronic pancreatitis, destruction of parenchyma comes along with infiltration of lymphocytes and macrophages. The phosphatidylserine receptor is expressed on the surface of macrophages and is crucial for the recognition and engulfment of apoptotic cells. In the present study, we investigated the role of this receptor and its relation to apoptosis in chronic pancreatitis.


METHODS
The expression and localization of PSR were analyzed by Northern blot analysis, RT-PCR, Western blot analysis and immunohistochemistry. Apoptosis was detected by the TUNEL method, and the RNA protection assay (RPA) was used to compare activation of apoptosis with PSR mRNA expression levels. In addition, the molecular data were related to clinicopathological parameters.


RESULTS
PSR mRNA expression was low to absent in normal pancreatic tissue samples. In human chronic pancreatitis, increased expression of PSR mRNA was present in 12 of 29 samples (41%). Up-regulation of PSR could be confirmed by Western blot analysis. In chronic pancreatitis tissue, PSR immunoreactivity was present in all islets, in some ductal cells and in macrophages. The RNA protection assay revealed high mRNA levels of the antiapoptotic genes bcl-2 and bfl-1 (P < 0.05) in chronic pancreatitis tissues with high PSR mRNA expression. The TUNEL apoptosis in situ detection method showed positive signals in some redifferentiating acinar cells and focally in acinar cells adjacent to stromal fibroblasts in chronic pancreatitis tissue samples. The distribution pattern of PSR on pancreatic cells in chronic pancreatitis corresponded to a great extent with regions of high apoptotic activity.


CONCLUSIONS
We show for the first time the presence of PSR in chronic pancreatitis on pancreatic cells other than macrophages in regions with high apoptotic activity. The coexpression and colocalization of this gene with other apoptosis mediators suggest its involvement in apoptotic processes. However, in chronic pancreatitis PSR is not only involved in phagocytosis of apoptotic cells by macrophages.
Köninger
Jörg
J
Department of General Surgery, University of Heidelberg, Heidelberg, Germany.
Balaz
Peter
P
Wagner
Markus
M
Shi
Xin
X
Cima
Igor
I
Zimmermann
Arthur
A
di Sebastiano
Pierluigi
P
Büchler
Markus W
MW
Friess
Helmut
H
D000293:Adolescent; D000328:Adult; D017209:Apoptosis / Q000502:physiology*; D002908:Chronic Disease; D005260:Female; D006801:Humans; D056484:Jumonji Domain-Containing Histone Demethylases; D008264:Macrophages / Q000502:physiology; D008297:Male; D008875:Middle Aged; D010179:Pancreas / Q000378:metabolism*; D010195:Pancreatitis / Q000503:physiopathology*; D010587:Phagocytosis / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis; D011956:Receptors, Cell Surface / Q000096:biosynthesis*
D012333:RNA, Messenger; D011956:Receptors, Cell Surface; C408123:phosphatidylserine receptor; C498707:JMJD6 protein, human; D056484:Jumonji Domain-Containing Histone Demethylases