Review for 10.1186/1471-230X-9-33 (2009)

Reviewer's report
Title:Food allergy alters jejunal circular muscle contractility and induces local
inflammatory cytokine expression in a mouse model
Version: 1Date:30 January 2009
Reviewer: Gabriella Di Felice
Reviewer's report:
Major Compulsory Revisions (that the author must respond to before a decision
on publication can be reached)
1. Relationship between jejunum hypocontractility and diarrhoea.
This functional relationship has not been fully analyzed in my opinion. The
authors conclude that “these changes may reflect a protective mechanism of the
gut in food allergy”, and discuss the similarity of such defensive response with
parasite infections, but the link between circular hypocontractility in the jejunum
and presence of diarrhoea is not clearly explained. The situation is probably
more complicated, because of the effects on longitudinal contractility (that could
be opposite), and the contribution of other gut segments (colon?) to the final
outcome of diarrhoea. Have you evaluated longitudinal contractility and in this
case found it different or similar to circular contractility? I fully agree that jejunum
is a crucial site for the induction of the response to food allergens, and the results
on the expression of Th2 inflammatory cytokines in this site confirm this view. On
the other hand, other intestinal districts (and their functional alterations) could be
more involved in the manifestation of diarrhoea, taking also into account the
particular physiologic characteristics of mouse intestine. Could you discuss these
aspects in more details?
2. Timing of diarrhoea symptoms.
In the previous paper by the same group reporting the development of the mouse
model, I read that diarrhoea appears after the fifth IG administration of OVA, and
5/6 mice have diarrhoea after the sixth dose. This peak corresponds to the peak
level of specific IgE and IgG antibodies, that increase significantly during the
challenge period. In the present paper, on which day have the diarrhoea
symptoms been assessed, in particular the analysis reported in Figures 2 and 3?
Please, specify this also in the section “Methods”. This is an important point to
properly discuss the correlation between IgE levels and other parameters in mice
showing or not diarrhoea symptoms.
3. Statistics
Different methods have been applied to the analysis of significance (see
“Methods”, page 10, paragraph “Statistics”). I think that the use of non-parametric
statistics (i.e.: Mann-Whitney’s U test) throughout the study would be more
appropriate when 5-8 mice per group are used. Why has Student’s t test been
used in Figure 3 and Mann-Whitney’s U test in Figure 5? And which is the test
applied in Table 1?
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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)
1. Please specify in each Figure legend the number of mice used in each
experiment, and how many experiment replicates have been performed.
2. Which is the dilution of serum samples in the ELISA assay for MMCP-1?
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Discretionary Revisions (which the author can choose to ignore)
1. Role of IL-13 and IL-13Ra2.
I wonder whether the IL-13 expression has also been evaluated, since its
up-regulation in jejunum has been described during food allergy. Moreover, it
could be interesting to study the role (if any) of the inhibitory IL-13Ra2, that is
highly expressed in smooth muscle.
2. Other symptoms of anaphylaxis.
Have you observed/evaluated other symptoms of anaphylaxis after allergen
challenge? Other food allergy murine models show systemic symptoms recorded
by a symptom score system, and histamine release both in serum and in faecal
samples (diarrhoea) collected after challenge.
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Acceptable
Statistical review: No, the manuscript does not need to be seen by a
statistician.
Declaration of competing interests:
I declare that I have no competing interests