Review for 10.1186/1471-230X-3-25 (2003)

Reviewer's report 
 Mice with targeted disruption of p8 gene show increased sensitivity to lipopolysaccharide and Title: 
DNA microarray analysis of livers reveals an aberrant gene expression response. 
Authors: 
Sophie Vasseur ( vasseur@marseille.inserm.fr )
Albrecht Hoffmeister ( hofa@medizin.uni-leipzig.de )
Andres Garcia-Montero ( angarmon@gugu.usal.es )
Dr Marc Barthet ( MBARTHET@mail.ap-hm.fr )
Laure Saint-Michel ( stmichel@inserm-adr.univ-mrs.fr )
Patrice Berthezene ( berthezene@marseille.inserm.fr )
Fritz Fiedler ( fritz.fiedler@urz.uni-heidelberg.de )
Daniel Closa ( dcabam@iibb.csic.es )
Jean Charles Dagorn ( dagorn@marseille.inserm.fr )
Dr Juan L Iovanna ( iovanna@marseille.inserm.fr )
 1  16 May 2003 Version: Date: 
 Gyorgy Hasko Reviewer: 
 A paper of considerable general medical or scientific interest Level of interest: 
 Unable to decide on acceptance or rejection until the authors have Advice on publication: 
responded to the compulsory revisions 
Using gene-targeted mice, this manuscript represents the first attempt to define a function for the p8 
gene under systemic stress induced by LPS. The manuscript demonstrates an important protective 
effect of p8 against LPS-induced lethality, as p8-deficient mice are more susceptible to the lethal effects of LPS than their wild-type counterparts. This increase in lethality in p8-deficient mice is 
associated with higher systemic levels of TNF-alpha and a clear increase in myeloperoxidase (MPO) 
and hydroperoxyde (HPO) levels in the pancreas, but not in the liver and lung. Finally, cDNA 
microarray analysis demonstrates a large number of differentially expressed genes in p8-KO vs. p8-WT mice. 
The major question that remains is which organ system(s) fail resulting in the eventual death of 
p8-KO mice. While this question may be difficult to answer, it would be important to examine 
whether the liver and pancreas are actually injured more in p8-KO mice. Both liver and pancreas 
injury should be quantified using standard laboratory methods by looking at liver and pancreatic 
enzymes in the plasma. It would also make sense to measure the levels of other cytokines (maybe IL-10, which is a major anti-inflammatory cytokine) and nitric oxide levels from the plasma. Data obtained from these experiments could give additional insight into the pathomechanism of p8 
deficiency, therefore it is important that the authors perform some of these experiments. 
The time course of TNF-a after LPS is surprisingly delayed in both the p8 KO and WT mice, as 
TNF-a usually peaks at around 3-4 hours after LPS administration and it is difficult to detect it at 
10-12 hours post-LPS. 
TNF-alpha mRNA does not show up in the Afffymetrix data, which is difficult to reconcile with the fact 
that high levels of TNF-alpha are detected in the plasma at this late time point and that Kupffer cells 
are the major producers of TNF-alpha after LPS administration. In the same light, it should be 
explained why many proinflammatory factors normally associated with LPS administration, including 
other cytokines, nitric oxide synthase, cyclooxygenase are not present on the gene chip. 
In light of all the above plus the fact that p8 was originally cloned from the pancreas, it is not clear 
why the liver was chosen for the Affymetrix analysis. 
There is an impressive number of genes altered by p8-deficiency. Does this pattern of changes in 
gene expression suggest any possible mechanisms of how p8 could effect gene transcription? 
Finally, although the LPS model used in this paper may be useful as an initial test to investigate 
stress pathways, it is getting increasingly clear that this model has no clinical relevance. 
Competing interests: 
None declared.