Review for 10.1186/1471-230X-13-165 (2013)

Reviewer's report
Title:Effects of Interleukin-4 or Interleukin-10 Gene Therapy on
Trinitrobenzenesulfonic Acid-Induced Mouse Colitis
Version: 1Date:30 June 2013
Reviewer: Fermin Sanchez de Medina
Reviewer's report:
The manuscript by Xiong et al. describes a gene therapy experiment on the
TNBS mouse model of colitis. Their results indicate that IL-4 or IL-10 increase is
beneficial, while combined therapy is actually deleterious, despite a positive
effect on TNF and IL-6. The study is interesting, generally well conducted and
presented. I have some comments as follows:
Major comments
1. The design leaves off a normal group. This is not absolutely required, but it
would give a reference on the degree of inflammation, i.e. what is the score of a
noncolitic mouse? According to methods this could easily reach 1-2. Also
relevant for cytokines.
2. Another aspect of the design is the fact that half a gene dose was used in the
combined group. This complicates the interpretation of the results.
3. My own interpretation of the data differs from that of the authors. First, the only
colonic effect of IL-4 or IL-10 transfer is possibly on IFN-g (statistical analysis
was apparently not performed except against the TNBS group). Histological
score was actually reduced by the vector alone, and it is unclear whether gene
carrying plasmid had an additional effect or not. But it is indisputable that TNF
and IL-6 are identical. Thus the main impact is on body weigth/DAI. Taken
together with the intraperitoneal pathway, these data suggest that the effect if
systemic rather than strictly colonic.
4. Why didn’t the authors measure IL-10 and IL-4 by qPCR? This is
incomprehensible (to say the least) since they used the technique for other not
so relevant endpoints.
5. Transfection technology was used very effectively in this study. Although
vaguely familiar with this approach, I was surprised to see this successful
outcome. It would be interesting to complement the manuscript with any more
data the authors have, or alternatively to provide some insight from previous
papers.
6. IL-4 is expected to produce inflammation – it is an inflammatory cytokine,
although it tends to limit Th1 responses and in such context it can be
anti-inflammatory.
7. The model used may or may not be acute in nature. In mice, as far as I know,
a single dose of TNBS/ethanol without previous sensitization produces a
response similar to that in the rat, peaking at 2-4 days with necrosis and fibrosis
of the tissue, followed by slow recovery. After a few days, depending on the
dose, the colon is scarred and physiologically altered but otherwise essentially
normal. When sensitization and sometimes repeated doses are carried out, the
outcome is more chronic, and at least partially this seems to be the case here.
Thus the model should be better described in this regard (ref. Nat Protoc.
2007;2(3):541-6).
8. The discussion was nicely written in that it kept to the point and avoided
overinterpretation. However it should be now amended to feature the comments
above (or rebuttal).
Minor comments
1. The order of presentation in Fig. 1 is not adequate. As mentioned above, Fig.
1 should actually feature qPCR data.
2. The Background section may be shortened a little.
3. Please do not use ‘pathologic’ to refer to histological analysis. Although
widespread, all the measurements provided are indeed ‘pathologic’, aren’t they?
4. Please revise the manuscript for some typos (minor) and weird expressions.
5. Please refer always to the combination group as IL-4+IL-10 or ‘combination’
group.
6. Is combined results and discussion allowed in the journal?
Level of interest: An article of importance in its field
Quality of written English: Needs some language corrections before being
published
Statistical review: Yes, and I have assessed the statistics in my report.
Declaration of competing interests:
No competing interest