Review for 10.1186/1471-230X-14-77 (2014)

Reviewer's report
Title:Correlation between depression, anxiety, and polymorphonuclear cells'
resilience in ulcerative colitis. The mediating role of heat shock protein 70.
Version: 1Date:16 February 2013
Reviewer: Ashwin Ananthakrishnan
Reviewer's report:
Barbatis and colleagues examine a potential mechanism for the influence of
depression and anxiety on IBD by examining the expression of the heat shock
protein 70 in mucosal biopsies, stratifying by depression or anxiety status. The
study included 29 patients with UC. Severity of inflammation varied from mild to
severe with most having moderate disease. The authors found downregulation of
HSP70 in inflamed ipithelium. Higher scores in all psychometric scales were
seen in patients with strong HSP70 immunoreactivity in PMN. The authors then
suggest that induction of HSP70 correlates with depression and anxiety.
While the study concept and hypothesis is interesting, I believe there are several
limitations to the manuscript.
1. I would suggest expanding a little on the role of HSP70 in IBD pathogenesis,
as well as why stress should influence HSP70 expression. Also why HSP70 as
opposed to some other proteins in the HSP family that have also shown an
association with IBD.
2. Please provide additional details about use of the anxiety and depression
questionnaires. Do these questionnaires assess recent (24 hrs, 1 week)
depressive symptoms (which could well be driven by severity of ongoing disease)
or baseline depression or anxiety unrelated to ongoing disease activity. Isn’t it
possible that high scores on the psychometric scales assessed cross-sectionally
at the same time as disease activity is assessed merely serves as a proxy for
disease severity? In which case, the present findings may imply that HSP70
expression is greater in severe disease (independent of psychosocial stress)?
How many patients had a prior known diagnosis of anxiety disorder or
depression?
3. While in their methods – the authors describe that HSP70 expression was
scored on a four point scale (negative, +/-. +, ++) – for most of the analyses
presented, HSP70 expression is analyzed on a dichotomous scale. Why was this
so, and please provide description for what constitutes HSP70 positive or HSP70
negative (Table 3).
4. For grading the severity of the colitis, the authors cite the paper by Dieleman
LA et al (ref#3). However, that paper examined a mouse model of DSS colitis,
and was not applied to human tissue. Why not use a more acceptable scoring
system for grading severity of human IBD?
5. What treatments were these patients on at the time of biopsy? Could ongoing
medical treatment influence HSP70 reactivity?
6. In the logistic regression described as showing an association between trait
anxiety, ZDRS, hospital depression scales, etc – what other variables were
adjusted for in the model? (other than corticosteroids alone)? One should
consider adjusting for measures such as duration of disease, other ongoing
medical treatments for UC, age, and gender.
7. It is not clear what HSP70i PMN positive and HSP70i PMN negative indicate
(main results, Table 3). How is this cumulative score calculated? Its not
mentioned anywhere in the methods.
8. One concern with the manuscript is the likelihood of false positive results
owing to the number of psychometric scales, and in particular the assessment of
constitutive and inducible HSP70 each at 9 different sites of expression. One
should consider adjusting for multiple hypothesis testing.
9. The results and interpretation seem somewhat unclear. It is stated that HSP70
expression is downregulated in patients with UC, rendering them more
vulnerable to inflammation-related stress. However, HSP70 expression positivity
correlates with depression and anxiety. Isn’t this counter-intuitive that
environmental factors that are associated (or hypothesized to be associated) with
greater disease activity in UC show an opposite direction of effect?
10. Table 1 – please present p-values.
11. In the background section, the authors state that “UC patients seem to be
influenced more than CD patients by external factors and less by genetics”.
While I agree with them that known genetic variants explain less of the heritability
for UC than CD, as far as I’m aware, there hasn’t been data to support that UC
patients are more influenced by external factors. Please provide the appropriate
citation for this assertion.
Level of interest: An article of limited interest
Quality of written English: Needs some language corrections before being
published
Statistical review: No, the manuscript does not need to be seen by a
statistician.