# The autophagy-repressive tissue hormone DBI/ACBP (diazepam binding inhibitor, acyl-CoA binding protein) suppresses anorexia

Hui Chen, Isabelle Martins, Guido Kroemer

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Hui Chen, Isabelle Martins, Guido Kroemer. The autophagy-repressive tissue hormone DBI/ACBP (diazepam binding inhibitor, acyl-CoA binding protein) suppresses anorexia. Autophagy, 2024, 20 (12), pp.2827 - 2829. 10.1080/15548627.2024.2402162. hal-05363744

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Submitted on 13 Nov 2025

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# The autophagy-repressive tissue hormone DBI/ACBP (diazepam binding inhibitor, acyl-CoA binding protein) suppresses anorexia

Hui Chen<sup>a,b</sup>, Isabelle Martins<sup>a,b</sup>, and Guido Kroemer <sup>a,b,c</sup>

<sup>a</sup>Team "Metabolism, Cancer & Immunity", Centre de Recherche des Cordeliers, UMRS 1138, Inserm, Université Paris Cité, Sorbonne Université, Paris, France; <sup>b</sup>Metabolomics and Cell Biology Platforms, Gustave Roussy Institute, Villejuif, France; <sup>c</sup>Institut du Cancer Paris CARPEM, Hôpital Européen Georges Pompidou, France-HP, Paris, France

## ABSTRACT

DBI/ACBP (diazepam binding inhibitor, acyl-CoA binding protein) is produced by multiple cell types and detectable in blood plasma. DBI acts on GABRA (gamma-aminobutyric acid type A receptor) complexes containing GABRG2 (gamma-aminobutyric acid type A receptor, subunit gamma 2) to inhibit macroautophagy/autophagy and hence can be considered as an "autophagy checkpoint". In patients with poor-prognosis anorexia nervosa, as well as in mice developing stress-induced anorexia, circulating DBI levels are reduced. Using a chemical-genetic system that makes it possible to control DBI secretion by hepatocytes, we showed that increasing DBI levels suffices to prevent anorexia induced by chronic restraint stress or chemotherapy with cisplatin, doxorubicin or paclitaxel in mice. At the mechanistic level, DBI administration acts through GABRA outside of the central nervous system and reduces the plasma levels of anorexigenic factors such as GDF15 (growth differentiation factor 15) and LCN2 (lipocalin 2), as well as anorexigenic signaling via the LCN2 receptor MC4R (melanocortin 4 receptor) in the hypothalamus. Accordingly, DBI supplementation stimulates food intake and normalizes whole body weight, body composition and metabolism in mouse models of anorexia. This normalization extends to the liver transcriptome and metabolome. Altogether, it appears that enhancing DBI levels constitutes a promising strategy for combating anorexia.

AN, anorexia nervosa; CNS, central nervous system; CRS, chronic restraint stress; DBI, diazepam binding inhibitor, acyl-CoA binding protein; ER, endoplasmic reticulum; GABA, gamma-aminobutyric acid; GABRA, gamma-aminobutyric acid type A receptor; GABRG2, gamma-aminobutyric acid type A receptor, subunit gamma 2; GDF15, growth differentiation factor 15; GPCR, G protein-coupled receptor; LCN2, lipocalin 2; MC4R, melanocortin 4 receptor; ODN, octadecaneuropeptide; RUSH, retention using selective hooks; SBP, streptavidin-binding peptide.

Anorexia nervosa (AN) is an often-life-threatening condition that has been attributed to psychosocial causes. At this point, no pharmacological treatment for this condition has been approved. Measurements of the circulating levels of major appetite regulators such as LEP (leptin) and GHRL (ghrelin and obestatin prepropeptide) yielded paradoxical results. Thus, the appetite inhibitor LEP is downregulated in AN patients, while the appetite stimulator GHRL is upregulated, meaning that these factors cannot explain the pathophysiology of this eating disorder. In contrast, the phylogenetically ancient appetite stimulator DBI/ACBP is reduced in the plasma from AN patients, especially in those individuals who show a hyperphagic-purgative form of the disease, which is of poor prognosis. Low plasma concentrations of DBI measured on the first day of hospitalization predict a high probability of relapse post-hospitalization linked to low caloric intake and physical hyperactivity.

These findings suggest a causal implication of reduced DBI levels in the pathogenesis of AN. Of note, in mice subjected to chronic restraint stress (CRS), which is a model of AN, DBI levels also drop as the animals lose weight.

An abundant literature indicates that DBI produced by astrocytes in the central nervous system (CNS) can give rise to several degradation products dubbed neuropeptides, the most prominent one being octadecaneuropeptide (ODN), that acts on neuronal G protein-coupled receptors (GPCRs) to inhibit food intake. In stark contrast, we found that peripherally (i.e., intravenously) administered recombinant DBI protein does not cross the blood-brain barrier and acts as a potent stimulator of food intake via an action on GABRA, which are not GPCRs but rather act as calcium channels. Indeed, mice bearing a point mutation (F77I) in the GABRG2 subunit of GABRA, which interferes with DBI binding, do not respond to the appetite-stimulatory effects of intravenously injected DBI. GABRA is also required for DBI to stimulate lipopeanabolic responses and to potently inhibit autophagy.

We took advantage of one particularity of DBI to engineer a chemical-genetic system allowing for the "gentle" control of DBI plasma concentrations without any injections, namely, by the oral administration of biotin [1]. Indeed, endogenous DBI is a leaderless protein that is subjected to unconventional, autophagy-dependent secretion. We fused the DBI protein to an N terminus that contains a leader peptide to facilitate import into the endoplasmic reticulum (ER) followed by a streptavidin-binding peptide (SBP), as well as a furin

## ARTICLE HISTORY

Received 28 July 2024
Revised 26 August 2024
Accepted 4 September 2024

## KEYWORDS

Appetite control; autophagy;
body mass index;
endozepine; metabolism;
obesity

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cleavage site. When transfected into cells that express a molar excess of ER-sessile streptavidin, this fusion protein is retained in the ER due to the interaction between streptavidin and SBP. However, after the addition of biotin, which has a high affinity for streptavidin, the interaction between streptavidin and SBP is competitively disrupted, allowing for the release of the SBP-DBI fusion protein into the Golgi apparatus. Here, the furin proteolytically removes SBP before DBI is released into the extracellular space. Hence, this methodology changes the mode of secretion of DBI toward a conventional, Golgi-dependent pathway. Hydrodynamic co-injection of two plasmids, one encoding ER-sessile streptavidin and another encoding the SBP-DBI fusion protein, into the tail vein of mice allows for the transgenic expression of this chemical-genetic system dubbed RUSH ("retention using selective hooks") in hepatocytes. Oral administration of biotin to such transgenic mice then triggers an elevation of circulating DBI that is secreted by the liver, which has become an endocrine organ.

Using this RUSH system, we could show that biotin-induced increases in DBI plasma concentrations suffice to prevent CRS-induced anorexia. Similarly, DBI prevents chemotherapy-induced weight loss in models of cachexia induced by cisplatin, doxorubicin or paclitaxel. We then performed a battery of tests to determine to which extent DBI

supplementation can reverse the anorexia-linked phenotype (Figure 1A). Magnetic resonance imaging revealed a DBI-induced normalization of body composition including body fat, muscle, and bone mass. Histological examinations indicated that DBI prevents adipocyte atrophy and maintains the diameter of skeletal muscle fibers in the physiological range. Metabolic cages were used to show that DBI normalizes whole-body metabolism at the levels of food and water intake as well as energy expenditure. Behavioral tests unraveled the capacity of DBI to reverse CRS-induced depression-like behavior. Examination of the liver transcriptome (by RNA-seq) and metabolome (by mass spectrometry) support the capacity of DBI to suppress CRS or cisplatin-induced alterations. Importantly, the administration of recombinant DBI protein or synthetic ODN peptide via osmotic pumps also has potent anorexia-suppressing effects in mice, suggesting that these results are translatable to human medicine.

(A) Methods used to demonstrate anorexia-suppressive effects of DBI in mouse models. (B) Hypothetical mode of action of DBI supplementation. Experimentally induced DBI elevation in the plasma has systemic metabolic effects, inhibiting autophagy, reducing circulating glucose and modifying catecholamine levels. In addition, DBI reduces plasma concentrations of GDF15 and LCN2. All these modifications suppress the anorexigenic circuitries and consequently lead

A

Anorexic stimuli

Chronic restraint stress

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Chemotherapy with
cisplatin, doxorubicin
or paclitaxel

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Biotin-induced secretion of DBI by hepatocytes
(chemical genetic system)

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Daily i.v. injection of
recDBI

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T
Osmotic pump releasing
recDBI

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Anorexia

↓ Food intake

↓ Body weight

↓ Adiposity

↑ Osteoporosis

↑ Sarcopenia

B

Peripheral effects via GABRA

Hepatic
secretion

↓

DBI increase in
plasma

↑

recDBI
delivery

Autophagy

↑ MTOR signaling

↓ Glycemia

↓ Corticosterone

↑ Norepinephrine

↓ GDF15

↓ LCN2

CNS effects

Hypothalamus

Melanocortin system

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↓ MC4R signaling
↓ DBI expression

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Orexigenic effects

Appetite stimulation

↑ Food intake

↑ Lipogenesis

↑ Adiposity

↑ Anabolism

<caption>Figure 1. Schematic overview of anorexia-preventive effects of DBI.</caption>
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to orexigenic effects. Of note, increases in peripheral DBI lead to a reduction in hypothalamic DBI protein expression. 3 V, third ventricle; Arc, arcuate nucleus; PVN, paraventricular nucleus.

Mechanistically (Figure 1B), the anorexia-preventive effects of DBI are lost in mice homozygous for the F77I mutation in GABRG2, supporting the role of GABRA acting outside of the CNS in appetite stimulation. DBI-induced prevention of CRS or chemotherapy-induced anorexia are associated with a partial modification of stress hormones including corticosterone and epinephrine. In addition, DBI reduces the plasma concentrations of GDF15, which has been linked to chemotherapy-induced cachexia, as well as hyperemesis in pregnant women. Of note, DBI supplementation diminishes circulating LCN2 protein concentrations, an anorexigenic factor, and down-regulates LCN2-elicited MC4R signaling in anorexigenic neurons of the hypothalamus. In addition, intravenous injections of DBI cause a reduction of DBI protein expression in the hypothalamus. These findings indicate that the peripheral and CNS pools of DBI indeed play separate and antagonistic roles in appetite control.

It appears intriguing that an autophagy-inhibitory protein such as DBI has anorexia-suppressive effects. We have found in the past that mice deficient for ATG4B, which exhibit a partial autophagy defect, lose less weight upon starvation for 24 or 48 h than their wild-type littermates. Hence autophagy might favor the development of anorexia. Of note, mice subjected to starvation exhibit a form of pathogenic cell death in some organs, such as the heart, that is mediated by excessive autophagy and has been dubbed as "autosis". Theoretically, DBI should suppress autosis. We will investigate this possibility in future studies.

## Acknowledgements

GK is supported by the Ligue contre le Cancer (équipe labellisée); Agence National de la Recherche (ANR-22-CE14-0066 VIVORUSH, ANR-23-CE44-0030 COPPERMAC, ANR-23-R4HC-0006 Ener-LIGHT); Association pour la recherche sur le cancer (ARC); Cancéropôle Ile-de-France; Fondation pour la Recherche Médicale (FRM); a donation by Elior; European Joint Programme on Rare Diseases (EJPRD) Wilsonmed; European Research Council Advanced Investigator Award (ERC-2021-ADG, Grant No. 101052444; project acronym: ICD-Cancer, project title: Immunogenic cell death (ICD) in the cancer-immune dialogue); The ERA4 Health Cardinoff Grant Ener-LIGHT; European Union Horizon 2020 research and innovation programmes Oncobiome (grant agreement number: 825410, Project Acronym: ONCOBIOME, Project title: Gut OncoMicrobiome Signatures [GOMS] associated with cancer incidence, prognosis and prediction of treatment response, Prevalung (grant agreement number 101095604, Project Acronym: PREVALUNG EU, project title: Biomarkers affecting the transition from cardiovascular disease to lung cancer: towards stratified interception), Neutrocure (grant agreement number 861878 : Project Acronym: Neutrocure; project title: Development of "smart" amplifiers of reactive oxygen species specific to aberrant polymorphonuclear neutrophils for treatment of inflammatory and autoimmune diseases, cancer and myeloablation); National support managed by the Agence Nationale de la Recherche under the France 2030 programme (reference number 21-ESRE-0028, ESR/Equipex+ Onco-Pheno-Screen); Hevolution Network on Senescence in Aging (reference HF-E Einstein Network); Institut National du Cancer (INCa); Institut Universitaire de France; LabEx

Immuno-Oncology ANR-18-IDEX-0001; a Cancer Research ASPIRE Award from the Mark Foundation; PAIR-Obésité INCa_1873, the RHUS Immunolife and LUCA-pi (ANR-21-RHUS-0017 and ANR-23-RHUS-0010, both dedicated to France Relance 2030); Seerave Foundation; SIRIC Cancer Research and Personalized Medicine (CARPEM, SIRIC CARPEM INCa-DGOS-Inserm-ITMO Cancer_18006 supported by Institut National du Cancer, Ministère des Solidarités et de la Santé and INSERM). This study contributes to the IdEx Université de Paris Cité ANR-18-IDEX-0001. Views and opinions expressed are those of the author(s) only and do not necessarily reflect those of the European Union, the European Research Council or any other granting authority. Neither the European Union nor any other granting authority can be held responsible for them.

## Disclosure statement

IM is a consultant for Osasuna Therapeutics. GK has been holding research contracts with Daiichi Sankyo, Eleor, Kaleido, Lytix Pharma, PharmaMar, Osasuna Therapeutics, Samsara Therapeutics, Sanofi, Sutro, Tollys, and Vascage. GK is on the Board of Directors of the Bristol Myers Squibb Foundation France. GK is a scientific co-founder of everImmune, Osasuna Therapeutics, Samsara Therapeutics and Therafast Bio. GK is in the scientific advisory boards of Hevolution, Institut Servier, Longevity Vision Funds and Rejuveron Life Sciences. GK is the inventor of patents covering therapeutic targeting of aging, cancer, cystic fibrosis and metabolic disorders. GK's wife, Laurence Zitvogel, has held research contracts with Glaxo Smyth Kline, Incyte, Lytix, Kaleido, Innovate Pharma, Daiichi Sankyo, Pilege, Merus, Transgene, 9 m, Tusk and Roche, was on the on the Board of Directors of Transgene, is a cofounder of everImmune, and holds patents covering the treatment of cancer and the therapeutic manipulation of the microbiota. GK's brother, Romano Kroemer, was an employee of Sanofi and now consults for Boehringer-Ingelheim. The funders had no role in the design of the study; in the writing of the manuscript, or in the decision to publish the results.

## Funding

The work was supported by the Agence Nationale de la Recherche [ANR-23-R4HC-0006 Ener-LIGHT]; Agence Nationale de la Recherche [ANR-23-CE44-0030 COPPERMAC]; Agence Nationale de la Recherche [ANR-22-CE14-0066 VIVORUSH]; Association pour la Recherche sur le Cancer Cancéropôle Ile de France Fondation pour la Recherche Médicale Institut National Du Cancer Institut Universitaire de France LabEx Immuno-Oncology ANR-18-IDEX-0001 PAIR-Obésité INCa_1873 the RHUS Immunolife and LUCA-pi [ANR-21-RHUS-0017 and ANR-23-RHUS-0010]; Hevolution Network on Senescence in Aging [HF-E Einstein Network]; National support managed by the Agence Nationale de la Recherche under the France 2030 programme [21-ESRE-0028, ESR/Equipex+ Onco-Pheno-Screen]; Neutrocure [grant agreement number 861878]; IdEx Université de Paris Cité ANR-18-IDEX-0001 European Union Horizon 2020 research and innovation programmes Oncobiome [825410]; The ERA4 Health Cardinoff Grant Ener-LIGHT European Research Council Advanced Investigator Award [ERC-2021-ADG, Grant No. 101052444]; Elior; European Joint Programme on Rare Diseases (EJPRD) Wilsonmed Prevalung [grant agreement number 101095604,]; SIRIC Cancer Research and Personalized Medicine Seerave Foundation.

## ORCID

Guido Kroemer http://orcid.org/0000-0002-9334-4405

## Reference

[1] Chen H, Moriceau S, Joseph A, et al. Acyl CoA binding protein for the experimental treatment of anorexia. Sci Transl Med. 2024;16:eadl0715.