Title: Hepatic recruitment of myeloid-derived suppressor cells upon liver injury promotes both
liver regeneration and fibrosis
Version: 1 Date: 23 May 2023
Reviewer's report:
Zhang et al. showed that the recruitment of MDSCs, in particular, M-MDSCs during hepatic
inflammation contributed to either proliferation of hepatocytes and activation of profibrotic
HSCs. CD11b+Gr1+ cells are well quantified by flow cytometry using multiple in vivo models
of hepatic inflammation. The authors performed in vitro co-culture of MDSCs and liver tissues
using a transwell to see the effects of MDSC-derived soluble factors to hepatocytes or HSCs.
They suggested that MDSCs promote proliferation of hepatocytes (from co-cultured liver
tissues) via the expression of  TGF-beta, VEGF, IL-10 and HGF.
However, the suggested mechanism is descriptive. While the expression of  TGF-beta and IL-10
by MDSCs are well known, but there is no data showing a direct evidence of VEGF and HGF
expression in MDSCs. The roles of those immunosuppressive cytokines and growth factors
are distinct. Increased proliferation of liver cells by HGF or VEGF is acceptable. However,
it is hard to understand how TGF-beta and IL-10 can enhance hepatocyte proliferation. In the
previous study (PNAS June 1992, Vol 89, 5408-5412), Oberhammer et al. showed that TGF-beta
treatment to hepatocytes induced their apoptosis in vitro. In addition, it is well-known that TGF-
beta-mediated expression of CDK inhibitors reduces cell proliferation. On top of that, IL-10 also
plays anti-fibrotic roles in HSCs (Experimental Cell Research Feb 2022, Vol 411 Issue 2).  I was
wondering how TGF-beta and IL-10 promoted hepatocyte proliferation during the co-culture.
In the co-culture experiments, intracellular staining of VEGF and HGF in MDCSs and flow
cytometry might be a possible experiment to prove the expression of these growth factors by
MDSCs.
Statistic analyses are largely missing in figures (Fig.1, 2, 3, 4D, 5C).
There is a lack of data in Fig. 3C. The authors mentioned that this data is showing M-MDSCs
as a main MDSC population in liver inflammation, which is missing.
Overall, it is difficult to accept the current version of manuscript for publication. The underlying
mechanisms of MDSCs in hepatocytes proliferation and activation of HSCs should be more
thoroughly tested to support the authors' argument.
Title: Hepatic recruitment of myeloid-derived suppressor cells upon liver injury promotes both
liver regeneration and fibrosis
Version: 1 Date: 23 May 2023
Reviewer's report:
Zhang et al. showed that the recruitment of MDSCs, in particular, M-MDSCs during hepatic
inflammation contributed to either proliferation of hepatocytes and activation of profibrotic
HSCs. CD11b+Gr1+ cells are well quantified by flow cytometry using multiple in vivo models
of hepatic inflammation. The authors performed in vitro co-culture of MDSCs and liver tissues
using a transwell to see the effects of MDSC-derived soluble factors to hepatocytes or HSCs.
They suggested that MDSCs promote proliferation of hepatocytes (from co-cultured liver
tissues) via the expression of  TGF-beta, VEGF, IL-10 and HGF.
However, the suggested mechanism is descriptive. While the expression of  TGF-beta and IL-10
by MDSCs are well known, but there is no data showing a direct evidence of VEGF and HGF
expression in MDSCs. The roles of those immunosuppressive cytokines and growth factors
are distinct. Increased proliferation of liver cells by HGF or VEGF is acceptable. However,
it is hard to understand how TGF-beta and IL-10 can enhance hepatocyte proliferation. In the
previous study (PNAS June 1992, Vol 89, 5408-5412), Oberhammer et al. showed that TGF-beta
treatment to hepatocytes induced their apoptosis in vitro. In addition, it is well-known that TGF-
beta-mediated expression of CDK inhibitors reduces cell proliferation. On top of that, IL-10 also
plays anti-fibrotic roles in HSCs (Experimental Cell Research Feb 2022, Vol 411 Issue 2).  I was
wondering how TGF-beta and IL-10 promoted hepatocyte proliferation during the co-culture.
In the co-culture experiments, intracellular staining of VEGF and HGF in MDCSs and flow
cytometry might be a possible experiment to prove the expression of these growth factors by
MDSCs.
Statistic analyses are largely missing in figures (Fig.1, 2, 3, 4D, 5C).
There is a lack of data in Fig. 3C. The authors mentioned that this data is showing M-MDSCs
as a main MDSC population in liver inflammation, which is missing.
Overall, it is difficult to accept the current version of manuscript for publication. The underlying
mechanisms of MDSCs in hepatocytes proliferation and activation of HSCs should be more
thoroughly tested to support the authors' argument.
Please review this paper.
user
Title: Hepatic recruitment of myeloid-derived suppressor cells upon liver injury promotes both
liver regeneration and fibrosis
Version: 1 Date: 23 May 2023
Reviewer's report:
Zhang et al. showed that the recruitment of MDSCs, in particular, M-MDSCs during hepatic
inflammation contributed to either proliferation of hepatocytes and activation of profibrotic
HSCs. CD11b+Gr1+ cells are well quantified by flow cytometry using multiple in vivo models
of hepatic inflammation. The authors performed in vitro co-culture of MDSCs and liver tissues
using a transwell to see the effects of MDSC-derived soluble factors to hepatocytes or HSCs.
They suggested that MDSCs promote proliferation of hepatocytes (from co-cultured liver
tissues) via the expression of  TGF-beta, VEGF, IL-10 and HGF.
However, the suggested mechanism is descriptive. While the expression of  TGF-beta and IL-10
by MDSCs are well known, but there is no data showing a direct evidence of VEGF and HGF
expression in MDSCs. The roles of those immunosuppressive cytokines and growth factors
are distinct. Increased proliferation of liver cells by HGF or VEGF is acceptable. However,
it is hard to understand how TGF-beta and IL-10 can enhance hepatocyte proliferation. In the
previous study (PNAS June 1992, Vol 89, 5408-5412), Oberhammer et al. showed that TGF-beta
treatment to hepatocytes induced their apoptosis in vitro. In addition, it is well-known that TGF-
beta-mediated expression of CDK inhibitors reduces cell proliferation. On top of that, IL-10 also
plays anti-fibrotic roles in HSCs (Experimental Cell Research Feb 2022, Vol 411 Issue 2).  I was
wondering how TGF-beta and IL-10 promoted hepatocyte proliferation during the co-culture.
In the co-culture experiments, intracellular staining of VEGF and HGF in MDCSs and flow
cytometry might be a possible experiment to prove the expression of these growth factors by
MDSCs.
Statistic analyses are largely missing in figures (Fig.1, 2, 3, 4D, 5C).
There is a lack of data in Fig. 3C. The authors mentioned that this data is showing M-MDSCs
as a main MDSC population in liver inflammation, which is missing.
Overall, it is difficult to accept the current version of manuscript for publication. The underlying
mechanisms of MDSCs in hepatocytes proliferation and activation of HSCs should be more
thoroughly tested to support the authors' argument.
assistant