Review for 10.1186/s12876-019-1156-0 (2020)

Reviewer’s report
Title: Deficiency of Gankyrin in the small intestine is associated with augmented colitis
accompanied by altered bacterial composition of intestinal microbiota
Version: 0 Date: 31 May 2019
Reviewer: Tadakazu Hisamatsu
Reviewer's report:
This manuscript entitled "Deficiency of Gankyrin in the small intestine is associated with augmented
colitis  accompanied  by  altered  bacterial  composition  of  intestinal  microbiota"  by  Sakurai  et  al
demonstrated  that  deficiency  of  Gankyrin  in  the  upper  small  intestine  caused  the  increase  of
susceptibility to DSS-induce colonic inflammation. The authors also demonstrated decrease Gankyrin
transcription in the small intestine may associate colonic involvement in patients with Crohn's disease.
The authors hypothesized that decrease production of defensins by Paneth cells may contribute to the
alteration of colonic flora composition and it may associate with the susceptibility of DSS-induced
colonic inflammation. 
The manuscript is well written.  Results are very interesting and may provide a new insight into
pathophysiology of Crohn's disease. However, this reviewer has several questions and concerns.
&lt;Major&gt;
If the decrease production of defensins by Paneth cells in Villin-Cre Gankyrinf/f mice associate with
susceptibility of DSS-induced colitis, colonic flora composition must be changed at basal level (OTU,
diversity, etc) between in the wild type and villin-Cre Gankyrinf/f mice. The authors compared gut
flora composition between DSS (+) vs DSS(-) condition. However, in the analysis after inducing
colonic inflammation, the change of gut flora may demonstrate only the result, but not the cause.
In relation to this, the results in co-housing experiments demonstrated that basal level of gut flora may
associate with the susceptibility to DSS-induced colitis. This reviewer suggests that the authors should
study flora composition in isolated Villin-Cre Gankyrinf/f mice with co-housing Villin-Cre Gankyrinf/f
mice.
It is very important that there is no change in the number of Paneth cells, so please indicate the actual
number in a chart. At the same time, it is also important that there is no change in Paneth cell functions.
Can you indicate the number of granules in the panel cell?
The authors described that stem cell marker were changed in Villin-Cre Gankyrinf/f mice. In Villin-Cre
Gankyrinf/f mice, was inflammation in the small intestine observed? Was stem cell function normal in
these mice? 
&lt;Minor&gt;
Was the data in Figure 1C obtained at day 7?
In the DSS experiments, the authors should show body weight change in the time course.
The results of AOM+DSS experiments could be omitted. 
Are the methods appropriate and well described?
If not, please specify what is required in your comments to the authors.
Yes
Does the work include the necessary controls?
If not, please specify which controls are required in your comments to the authors.
No
Are the conclusions drawn adequately supported by the data shown?
If not, please explain in your comments to the authors.
No
Are you able to assess any statistics in the manuscript or would you recommend an
additional statistical review?
If an additional statistical review is recommended, please specify what aspects require further
assessment in your comments to the editors.
I am able to assess the statistics
Quality of written English
Please indicate the quality of language in the manuscript:
Acceptable
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