Effects of Macronutrients on the In Vitro Production of ClpB, a Bacterial Mimetic Protein of α-MSH and Its Possible Role in Satiety Signaling

Manon Dominique,Sergueï Fetissov,Grégory Lambert,Pierre Déchelotte,Christine Bole-Feysot,Jonathan Breton,Charlène Guérin

doi:10.3390/nu11092115

Abstract

Gut microbiota can influence the feeding behavior of the host, but the underlying mechanisms are unknown. Recently, caseinolytic protease B (ClpB), a disaggregation chaperon protein of Escherichia coli, was identified as a conformational mimetic of α-melanocyte-stimulating hormone (α-MSH), an anorexigenic neuropeptide. Importantly, ClpB was necessary for E. coli to have an anorexigenic effect in mice, suggesting that it may participate in satiety signaling. To explore this further, we determined the short-term (2 h) effects of three macronutrients: protein (bovine serum albumin), carbohydrate (D-fructose) and fat (oleic acid), on the production of ClpB by E. coli and analyzed whether ClpB can stimulate the secretion of the intestinal satiety hormone, peptide YY (PYY). Isocaloric amounts of all three macronutrients added to a continuous culture of E. coli increased ClpB immunoreactivity. However, to increase the levels of ClpB mRNA and ClpB protein in bacteria and supernatants, supplementation with protein was required. A nanomolar concentration of recombinant E. coli ClpB dose-dependently stimulated PYY secretion from the primary cell cultures of rat intestinal mucosa. Total proteins extracted from E. coli but not from ClpB-deficient E. coli strains also tended to increase PYY secretion. These data support a possible link between E. coli ClpB and protein-induced satiety signaling in the gut.

Highlights

The composition of the gut microbiota has been associated with host metabolic phenotypes.For instance, colonization of germ-free mice with gut microbiota harvested from conventionally raised obese or lean mice results in similar host fatness to that of the donor mice [1]
After 2 h of nutrient provision (MH medium or macronutrients), there was a visible increase in the immunoreactivity of caseinolytic protease B (ClpB), (Figure 2A,B) reaching about 28% of the total number of bacterial cells
We showed that E. coli ClpB was able to stimulate peptide YY (PYY) secretion in rat intestinal mucosa

Summary

Introduction

The composition of the gut microbiota has been associated with host metabolic phenotypes. Colonization of germ-free mice with gut microbiota harvested from conventionally raised obese or lean mice results in similar host fatness to that of the donor mice [1]. The underlying mechanisms are not completely understood. They may include both direct energy-extracting properties of the gut bacteria as well as the regulation of energy metabolism by bacteria-host interactions, including host appetite and nutrient intake [2]. Proteins produced by commensal bacteria, such as Escherichia coli, were shown to stimulate satiety signaling in rodents [3].

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Discussion

Conclusion