Review for 10.1186/s12876-015-0409-9 (2015)

Reviewer's report
Title:Deficiency of Endothelial Nitric Oxide Synthase Exacerbates Early-stage
Non-Alcoholic Fatty Liver Disease Pathogenesis by Changing the Fat Distribution
Version:1Date:14 August 2015
Reviewer: Fanyin Meng
Reviewer's report:
Minor Essential Revisions
In the current manuscript submitted by Yuichi Nozaki et al. the authors aimed to
investigate the role of eNOS-derived NO in NAFLD pathogenesis using systemic
eNOS-knockout mice fed a high-fat diet. Lipid accumulation and inflammation
was more extensive in the liver and lipid accumulation was less extensive in the
visceral fat tissue in eNOS-knockout mice, compared with wild-type mice, after
12 weeks of being fed a high-fat diet. While systemic insulin resistance was
comparable between the eNOS-knockout and wild-type mice fed a high-fat diet,
hepatic tissue blood flow was significantly suppressed in the eNOS-knockout
mice, compared with the wild-type mice, in mice fed a high-fat diet. The
microsomal triglyceride transfer protein activity was down-regulated in
eNOS-knockout mice, compared with wild-type mice, in mice fed a high-fat diet.
Overall a deficiency of eNOS-derived NO may change the fat distribution of liver
and visceral fat, thereby promoting the progression of disease in an
HFD-induced, early-stage NASH mouse model by changing the hepatic tissue
blood flow. The current study also examined the fat distribution and the
pathogenesis of NAFLD/NASH using an imaging procedure in an NAFLD/NASH
mouse model with or without the eNOS gene. It is an interesting manuscript with
the innovative concept. The overall findings may provide translational potential to
address specific clinical issues related to the pathogenesis of NAFLD/NASH.
However, some minor issues should be fixed before further consideration.
Comments:
1) The recent data from Sheldon RD et al (Am J Physiol Gastrointest Liver
Physiol. 2015 Mar 15;308(6):G540-9) have demonstrated that systemic NOS
inhibition in the obese OLETF rats reduced hepatic mitochondrial respiration,
increased hepatic triacylglycerol accumulation, and increased hepatic
inflammation. The current studies only have very limited data on hepatic tissue
blood flow which may too superficial. Therefore some hepatic mitochondrial
respiration markers and hepatic inflammation statues should be verified in the
current project to further support the central hypothesis.
2) For hepatic inflammation related studies, neutrophil infiltration detection should
be carried out in the liver from eNOS-knockout mice fed a high-fat diet. The
presence of neutrophils should be assessed by the measurement of liver tissue
myeloperoxidase (MPO), and the degree of neutrophil liver infiltration should be
determined by the naphthol AS-D chloroacetate esterase technique
3) Serum ALT and AST values should be included in Table 2.
4) The fibrosis stage in Table 3 should be verified by Sirius red staining.
5) The relationship between the changes of hepatic blood flow and the degrees
of liver injury should be further established.
6) To be consistent with Fig. 2 C&D, Fig. 3 also should include four groups
instead of two groups.
7) In “List of abbreviations”, the font and size should be consistent.
Level of interest: An article of importance in its field
Quality of written English: Acceptable
Statistical review: Yes, but I do not feel adequately qualified to assess the
statistics.
Declaration of competing interests:
I have no conflict of interest.