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Letter to the EditorMetabolism Open Access | 10.1172/JCI156247

Response to Kunos et al. and Lotersztajn and Mallat

Simeng Wang,1 Qingzhang Zhu,1 Guosheng Liang,1,2 Tania Franks,3 Magalie Boucher,3 Kendra K. Bence,4 Mingjian Lu,4 Carlos M. Castorena,1 Shangang Zhao,1 Joel K. Elmquist,1 Philipp E. Scherer,1 and Jay D. Horton1,2

1 Department of Internal Medicine and

2Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

3Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Cambridge, Massachusetts, USA.

4Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, Massachusetts, USA.

Address correspondence to: Jay D. Horton, Departments of Internal Medicine and Molecular Genetics, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390-9046, USA. Phone: 214.648.9677; Email: Jay.Horton@UTSouthwestern.edu.

Find articles by Wang, S. in: JCI | PubMed | Google Scholar

1 Department of Internal Medicine and

2Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

3Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Cambridge, Massachusetts, USA.

4Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, Massachusetts, USA.

Address correspondence to: Jay D. Horton, Departments of Internal Medicine and Molecular Genetics, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390-9046, USA. Phone: 214.648.9677; Email: Jay.Horton@UTSouthwestern.edu.

Find articles by Zhu, Q. in: JCI | PubMed | Google Scholar |

1 Department of Internal Medicine and

2Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

3Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Cambridge, Massachusetts, USA.

4Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, Massachusetts, USA.

Address correspondence to: Jay D. Horton, Departments of Internal Medicine and Molecular Genetics, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390-9046, USA. Phone: 214.648.9677; Email: Jay.Horton@UTSouthwestern.edu.

Find articles by Liang, G. in: JCI | PubMed | Google Scholar

1 Department of Internal Medicine and

2Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

3Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Cambridge, Massachusetts, USA.

4Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, Massachusetts, USA.

Address correspondence to: Jay D. Horton, Departments of Internal Medicine and Molecular Genetics, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390-9046, USA. Phone: 214.648.9677; Email: Jay.Horton@UTSouthwestern.edu.

Find articles by Franks, T. in: JCI | PubMed | Google Scholar

1 Department of Internal Medicine and

2Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

3Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Cambridge, Massachusetts, USA.

4Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, Massachusetts, USA.

Address correspondence to: Jay D. Horton, Departments of Internal Medicine and Molecular Genetics, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390-9046, USA. Phone: 214.648.9677; Email: Jay.Horton@UTSouthwestern.edu.

Find articles by Boucher, M. in: JCI | PubMed | Google Scholar

1 Department of Internal Medicine and

2Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

3Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Cambridge, Massachusetts, USA.

4Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, Massachusetts, USA.

Address correspondence to: Jay D. Horton, Departments of Internal Medicine and Molecular Genetics, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390-9046, USA. Phone: 214.648.9677; Email: Jay.Horton@UTSouthwestern.edu.

Find articles by Bence, K. in: JCI | PubMed | Google Scholar |

1 Department of Internal Medicine and

2Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

3Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Cambridge, Massachusetts, USA.

4Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, Massachusetts, USA.

Address correspondence to: Jay D. Horton, Departments of Internal Medicine and Molecular Genetics, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390-9046, USA. Phone: 214.648.9677; Email: Jay.Horton@UTSouthwestern.edu.

Find articles by Lu, M. in: JCI | PubMed | Google Scholar |

1 Department of Internal Medicine and

2Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

3Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Cambridge, Massachusetts, USA.

4Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, Massachusetts, USA.

Address correspondence to: Jay D. Horton, Departments of Internal Medicine and Molecular Genetics, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390-9046, USA. Phone: 214.648.9677; Email: Jay.Horton@UTSouthwestern.edu.

Find articles by Castorena, C. in: JCI | PubMed | Google Scholar |

1 Department of Internal Medicine and

2Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

3Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Cambridge, Massachusetts, USA.

4Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, Massachusetts, USA.

Address correspondence to: Jay D. Horton, Departments of Internal Medicine and Molecular Genetics, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390-9046, USA. Phone: 214.648.9677; Email: Jay.Horton@UTSouthwestern.edu.

Find articles by Zhao, S. in: JCI | PubMed | Google Scholar |

1 Department of Internal Medicine and

2Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

3Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Cambridge, Massachusetts, USA.

4Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, Massachusetts, USA.

Address correspondence to: Jay D. Horton, Departments of Internal Medicine and Molecular Genetics, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390-9046, USA. Phone: 214.648.9677; Email: Jay.Horton@UTSouthwestern.edu.

Find articles by Elmquist, J. in: JCI | PubMed | Google Scholar

1 Department of Internal Medicine and

2Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

3Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Cambridge, Massachusetts, USA.

4Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, Massachusetts, USA.

Address correspondence to: Jay D. Horton, Departments of Internal Medicine and Molecular Genetics, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390-9046, USA. Phone: 214.648.9677; Email: Jay.Horton@UTSouthwestern.edu.

Find articles by Scherer, P. in: JCI | PubMed | Google Scholar

1 Department of Internal Medicine and

2Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

3Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Cambridge, Massachusetts, USA.

4Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, Massachusetts, USA.

Address correspondence to: Jay D. Horton, Departments of Internal Medicine and Molecular Genetics, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390-9046, USA. Phone: 214.648.9677; Email: Jay.Horton@UTSouthwestern.edu.

Find articles by Horton, J. in: JCI | PubMed | Google Scholar |

Published January 4, 2022 - More info

Published in Volume 132, Issue 1 on January 4, 2022
J Clin Invest. 2022;132(1):e156247. https://doi.org/10.1172/JCI156247.
© 2022 Wang et al. This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
Published January 4, 2022 - Version history
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Related articles:

Cannabinoid receptor 1 signaling in hepatocytes and stellate cells does not contribute to NAFLD
Simeng Wang, … , Philipp E. Scherer, Jay D. Horton
Simeng Wang, … , Philipp E. Scherer, Jay D. Horton
Research Article Hepatology Metabolism Article has an altmetric score of 9

Cannabinoid receptor 1 signaling in hepatocytes and stellate cells does not contribute to NAFLD

Abstract

The endocannabinoid system regulates appetite and energy expenditure and inhibitors of cannabinoid receptor 1 (CB-1) induce weight loss with improvement in components of the metabolic syndrome. While CB-1 blockage in brain is responsible for weight loss, many of the metabolic benefits associated with CB-1 blockade have been attributed to inhibition of CB-1 signaling in the periphery. As a result, there has been interest in developing a peripherally restricted CB-1 inhibitor for the treatment of nonalcoholic fatty liver disease (NAFLD) that would lack the unwanted centrally mediated side effects. Here, we produced mice that lacked CB-1 in hepatocytes or stellate cells to determine if CB-1 signaling contributes to the development of NAFLD or liver fibrosis. Deletion of CB-1 in hepatocytes did not alter the development of NAFLD in mice fed a high-sucrose diet (HSD) or a high-fat diet (HFD). Similarly, deletion of CB-1 specifically in stellate cells also did not prevent the development of NAFLD in mice fed the HFD, nor did it protect mice from carbon tetrachloride–induced fibrosis. Combined, these studies do not support a direct role for hepatocyte or stellate cell CB-1 signaling in the development of NAFLD or liver fibrosis.

Authors

Simeng Wang, Qingzhang Zhu, Guosheng Liang, Tania Franks, Magalie Boucher, Kendra K. Bence, Mingjian Lu, Carlos M. Castorena, Shangang Zhao, Joel K. Elmquist, Philipp E. Scherer, Jay D. Horton

×
Do endocannabinoids acting via hepatic CB-1 contribute to NAFLD and hepatic insulin resistance?
George Kunos, … , Tony Jourdan, Joseph Tam
George Kunos, … , Tony Jourdan, Joseph Tam
Letter to the Editor Metabolism
Does CB-1 in hepatic stellate cells contribute to liver fibrosis?
Sophie Lotersztajn, Ariane Mallat
Sophie Lotersztajn, Ariane Mallat
Letter to the Editor Hepatology

Does CB-1 in hepatic stellate cells contribute to liver fibrosis?

Abstract

Authors

Sophie Lotersztajn, Ariane Mallat

×
The authors reply:

Kunos et al. (1) raise several issues that we can further clarify. We acknowledge that we could not use the TD97070 diet, which contains Primex hydrogenated vegetable shortening, a trans fat–rich mix that was discontinued in 2018. Therefore, we used the D12492 diet. The fat content in TD97070 and D12492 is 33.5% and 34.9% of calories, with a saturated fat content of 45% and 32%, respectively. A possible more important difference is that TD97070 contains 24% trans fats. Nevertheless, the cited mechanism by which the high-fat diet (HFD) increases anandamide (AEA) is that monounsaturated fatty acids (MUFAs) generated via SCD1 activity (but not diet-derived MUFAs) function as endogenous fatty acid amide hydrolase inhibitors mediating HFD-induced increases in hepatic AEA, which then activates hepatic cannabinoid receptor 1 (CB-1) to induce insulin resistance (2). This is precisely why we also carried out studies using a high-sucrose diet to maximally induce SREBP-1c, SCD1, and MUFA synthesis (3, 4). Despite induction of SCD1, we found no differences between Cnr1fl/fl and Hep-Cnr1–/– mice (Figure 2 in ref. 5). This mechanism is also operational in insulin-resistant states, which leads to activation of SCD1 and MUFA synthesis (6), yet, in our study, did not induce CB-1.

Regarding the genetic background, our Cnr1fl/fl mice were generated on a C57BL/6N background and backcrossed with C57BL/6J mice for six generations. Given the potentially different mixtures of 6N and 6J strains used by the various research groups, it is impossible to exclude subtle genetic differences that might contribute to phenotypic differences.

We agree that a rescue model of CB-1 reexpressed in hepatocytes of Cnr1–/– mice would be ideal. However, the available liver-specific promoters would massively overexpress CB-1 compared with the extremely low physiological levels of CB-1 expression in hepatocytes. The overexpression would preclude reaching any firm conclusions.

Finally, it was stated that we did not cite any human or animal studies consistent with the role of CB-1 in insulin resistance. Relevant references were included in which there were no changes in body weights (refs. 25–30 in our study).

In response to Lotersztajn and Mallat (7), it is true that we relied on CB-1 mRNA and not protein measurements. We attempted to measure CB-1 protein in liver membranes using three different commercially available antibodies but were unsuccessful, despite detecting CB-1 in extracts from hypothalami. An additional issue raised was that the single-cell RNA-Seq (scRNA-Seq) was performed in livers of HFD-fed mice, a model, they state, in which hepatic stellate cells (HSCs) “are hardly activated.” The purpose of the scRNA-Seq study was to ensure that we were not overlooking a cell type in which CB-1 became highly expressed in response to the diets. The CCl4 studies were used to maximally increase stellate cell activation and induce fibrosis, which occurred to an identical extent in WT and Hsc-Cnr1–/– mice. Since the primary purpose was to determine whether deleting CB-1 in HSCs alters the development of fibrosis, we did not further investigate CB-1 signaling. We agree that fibrosis is a complex process involving multiple cell types in liver. Our data only show that there was no clear contribution of CB-1 in hepatocytes and HSCs to the development of fibrosis or insulin resistance.

Footnotes

Conflict of interest: JDH is a consultant for Pfizer. JKE and GL conduct sponsored research with Pfizer.

Reference information: J Clin Invest. 2021;132(1):e156427. https://doi.org/10.1172/JCI156247.

See the related article at Cannabinoid receptor 1 signaling in hepatocytes and stellate cells does not contribute to NAFLD.

See the related Letter to the Editor at Does CB-1 in hepatic stellate cells contribute to liver fibrosis?

See the related Letter to the Editor at Do endocannabinoids acting via hepatic CB-1 contribute to NAFLD and hepatic insulin resistance?

References
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Version history
  • Version 1 (January 4, 2022): Electronic publication
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