Review for 10.1186/1471-230X-6-16 (2006)

Reviewer's report 
 Caerulein-Induced Acute Pancreatitis in Mice that Constitutively Overexpress Reg/PAP Genes Title: 
 1  11 January 2006 Version: Date: 
 Marc Chanson Reviewer: 
Reviewer's report: 
General 
It is well accepted that Reg/PAP genes are increased during pancreas injury as observed in acute 
pancreatitis. From the known functions of these genes, it is also believed that they may exert a 
protective role against pancreatic injury. Whether increased expression of Reg/PAP gene indeed 
weakens the severity of acute pancreatitis has not yet been investigated. To address this question, 
Norkina et al studied experimentally-induced acute pancreatitis in CFTR null mouse (CF mouse). 
These mice were chosen because of their higher mRNA level for Reg/PAP as compared to wild-type 
animals. 
In contrast to the expected results, no striking difference in cerulein-induced acute pancreatitis 
between CF and wild-type mice was observed. These observations confirmed a very recent study 
(2005) reporting a mild pancreatic phenotype in the CF mouse challenged with cerulein. In addition, 
this study brings novel information on pancreas injury at early time after cerulein treatment in CF and 
reports detailed characterization of Reg/PAP gene mRNAs and Reg3alpha protein expression with 
time. 
Several concerns need however to be addressed: 
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Major Compulsory Revisions (that the author must respond to before a decision on publication can 
be reached) 
Figure 4 somehow appears incomplete or inappropriate. If basal MPO is higher in the CF mouse, it 
seems logical that this value will increase further with pancreatic injury (1h). However, it is not clear 
why lung MPO decreases at times (7 and 12h) of maximal pancreatic injury. Also, why at these time 
points, the difference between CF and control mice is no longer observed? 
The authors suggest the appealing idea that increased production of Reg3 alpha by the injured 
pancreas may contribute to lung inflammation. In the CF mouse, reg3alpha expression remains constant during cerulein treatment. How the authors can then relate these two observations? 
It is also unclear if the increase in lung MPO at 3d is real or is due to a low number of experiments 
(as mentioned by the authors). This needs to be clarified. Why lung injury will be transient, higher at 
3d but not at 12h or 7d after cerulein? Are the CF lung samples used at 3d from the same mice used 
to measure pancreatic MPO? Without further characterization of the links between Reg/PAP and 
lung injury, one would suggest to delete Fig 4 and the conclusion of the paper that these genes 
contribute to lung inflammation. 
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Minor Essential Revisions (such as missing labels on figures, or the wrong use of a term, which the 
author can be trusted to correct) 
Data in Figure 2 are difficult to interpret. Why edema is that high in controls? Why edema decreased 
below that of the initial value 7d after cerulein treatment in wild-type mice? There is also no change 
in edema in the CF mouse in response to cerulein whereas serum amylase and pancreatic MPO markedly increased? Is basal edema in these mice a possible consequence of the liquid diet? 
The authors state that recovery of acute pancreatitis is slowed down in the CF mice. This may be 
true but relies only on one time point (Fig 3, 3d) that is even not statistically significant from the value 
measured in controls. 
Figures 1 to 3 could be combined to Figure 1A,B,C. 
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Discretionary Revisions (which the author can choose to ignore) 
The authors conclude that cerulein-induced acute pancreatitis is not different in CF mice from 
controls despite high levels of Reg/PAP gene expression. Would have the severity of acute 
pancreatitis been higher in the absence of Reg/PAP overexpression in CF mice? 
The RT-PCR and Reg3alpha expression data are very well done. It is interesting to note that the 
transient decrease in Reg3alpha occurs at very early time after cerulein treatment (first hours). While 
there is a small window of time whereby Reg3apha decreases markedly in control mice, this protein 
remains at high levels of expression in CF mice. This may have important consequences on the 
evolution of acute pancreatitis, possibly by altering the acinar cell apoptosis/necrosis ratio, as 
suggested by the authors. Thus, this paper brings an additional argument in the support of the 
hypothesis that apoptosis in the pancreas may exert protective effect against injury. Would it be 
correct to propose that acinar cell apoptosis refrains the severity of acute pancreatitis in control mice 
whereas increased expression of Reg/PAP would exert anti-inflammatory roles in the CF pancreas. 
With these two protective effects, acute pancreatitis may not differ between CF and control mice in 
terms of severity on the long term but may explain difference on various aspects such as Reg3alpha 
localization, proportion of apoptotic acinar cells, or edema on shorter terms. 
The discussion is very well written. Page 21, line 6 : “from”. 
 Accept after minor essential revisions What next?: 
 An article of importance in its field Level of interest: 
 Acceptable Quality of written English: 
 No Statistical review: 
Declaration of competing interests: 
I declare that I have no competing interests