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Abstract
Advances in technology are only beginning to reveal the complex interactions between hosts and their resident microbiota that have co-evolved over centuries. In this review, we present compelling evidence that implicates the host-associated microbiome in the generation of 11β-hydroxyandrostenedione, leading to the formation of potent 11-oxy-androgens. Microbial steroid-17,20-desmolase cleaves the side-chain of glucocorticoids (GC), including cortisol (and its derivatives of cortisone, 5α-dihydrocortisol, and also (allo)- 3α, 5α-tetrahydrocortisol, but not 3α-5β-tetrahydrocortisol) and drugs (prednisone and dexamethasone). In addition to side-chain cleavage, we discuss the gut microbiome's robust potential to transform a myriad of steroids, mirroring much of the host's metabolism. We also explore the overlooked role of intestinal steroidogenesis and efflux pumps as a potential route for GC transport into the gut. Lastly, we propose several health implications from microbial steroid-17,20-desmolase function, including aberrant mineralocorticoid, GC, and androgen receptor signaling in colonocytes, immune cells, and prostate cells, which may exacerbate disease states.
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Affiliation(s)
- Lindsey K Ly
- Microbiome Metabolic Engineering Theme, Carl R. Woese Institute for Genomic Biology, Urbana, IL, 61801, USA; Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA; Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Heidi L Doden
- Microbiome Metabolic Engineering Theme, Carl R. Woese Institute for Genomic Biology, Urbana, IL, 61801, USA; Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Jason M Ridlon
- Microbiome Metabolic Engineering Theme, Carl R. Woese Institute for Genomic Biology, Urbana, IL, 61801, USA; Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA; Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Cancer Center of Illinois, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA.
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Doden HL, Pollet RM, Mythen SM, Wawrzak Z, Devendran S, Cann I, Koropatkin NM, Ridlon JM. Structural and biochemical characterization of 20β-hydroxysteroid dehydrogenase from Bifidobacterium adolescentis strain L2-32. J Biol Chem 2019; 294:12040-12053. [PMID: 31209107 DOI: 10.1074/jbc.ra119.009390] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 06/11/2019] [Indexed: 01/20/2023] Open
Abstract
Anaerobic bacteria inhabiting the human gastrointestinal tract have evolved various enzymes that modify host-derived steroids. The bacterial steroid-17,20-desmolase pathway cleaves the cortisol side chain, forming pro-androgens predicted to impact host physiology. Bacterial 20β-hydroxysteroid dehydrogenase (20β-HSDH) regulates cortisol side-chain cleavage by reducing the C-20 carboxyl group on cortisol, yielding 20β-dihydrocortisol. Recently, the gene encoding 20β-HSDH in Butyricicoccus desmolans ATCC 43058 was reported, and a nonredundant protein search yielded a candidate 20β-HSDH gene in Bifidobacterium adolescentis strain L2-32. B. adolescentis 20β-HSDH could regulate cortisol side-chain cleavage by limiting pro-androgen formation in bacteria such as Clostridium scindens and 21-dehydroxylation by Eggerthella lenta Here, the putative B. adolescentis 20β-HSDH was cloned, overexpressed, and purified. 20β-HSDH activity was confirmed through whole-cell and pure enzymatic assays, and it is specific for cortisol. Next, we solved the structures of recombinant 20β-HSDH in both the apo- and holo-forms at 2.0-2.2 Å resolutions, revealing close overlap except for rearrangements near the active site. Interestingly, the structures contain a large, flexible N-terminal region that was investigated by gel-filtration chromatography and CD spectroscopy. This extended N terminus is important for protein stability because deletions of varying lengths caused structural changes and reduced enzymatic activity. A nonconserved extended N terminus was also observed in several short-chain dehydrogenase/reductase family members. B. adolescentis strains capable of 20β-HSDH activity could alter glucocorticoid metabolism in the gut and thereby serve as potential probiotics for the management of androgen-dependent diseases.
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Affiliation(s)
- Heidi L Doden
- Microbiome Metabolic Engineering Theme, Carl R. Woese Institute for Genomic Biology, Urbana, Illinois 61801; Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Rebecca M Pollet
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Sean M Mythen
- Microbiome Metabolic Engineering Theme, Carl R. Woese Institute for Genomic Biology, Urbana, Illinois 61801; Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Zdzislaw Wawrzak
- Northwestern Synchrotron Research Center-LS-CAT, Northwestern University, Argonne, Illinois 60439
| | - Saravanan Devendran
- Microbiome Metabolic Engineering Theme, Carl R. Woese Institute for Genomic Biology, Urbana, Illinois 61801; Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Isaac Cann
- Microbiome Metabolic Engineering Theme, Carl R. Woese Institute for Genomic Biology, Urbana, Illinois 61801; Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801; Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Nicole M Koropatkin
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Jason M Ridlon
- Microbiome Metabolic Engineering Theme, Carl R. Woese Institute for Genomic Biology, Urbana, Illinois 61801; Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801; Cancer Center of Illinois, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801; Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.
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Abstract
A new concept is emerging in biomedical sciences: the gut microbiota is a virtual 'organ' with endocrine function. Here, we explore the literature pertaining to the role of gut microbial metabolism of endogenous adrenocorticosteroids as a contributing factor in the etiology of essential hypertension. A body of literature demonstrates that bacterial products of glucocorticoid metabolism are absorbed into the portal circulation, and pass through the kidney before excretion into urine. Apparent mineralocorticoid excess (AME) syndrome patients were found to have congenital mutations resulting in non-functional renal 11β-hydroxysteroid dehydrogenase-2 (11β-HSD2) and severe hypertension often lethal in childhood. 11β-HSD2 acts as a "guardian" enzyme protecting the mineralocorticoid receptor from excess cortisol, preventing sodium and water retention in the normotensive state. Licorice root, whose active ingredient, glycerrhetinic acid (GA), inhibits renal 11β-HSD2, and thereby causes hypertension in some individuals. Bacterially derived glucocorticoid metabolites may cause hypertension in some patients by a similar mechanism. Parallel observations in gut microbiology coupled with screening of endogenous steroids as inhibitors of 11β-HSD2 have implicated particular gut bacteria in essential hypertension through the production of glycerrhetinic acid-like factors (GALFs). A protective role of GALFs produced by gut bacteria in the etiology of colorectal cancer is also explored.
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Affiliation(s)
- David J Morris
- Department of Pathology and Laboratory Medicine, The Miriam Hospital, Warren Alpert Medical School of Brown University, Providence, RI, United States.
| | - Jason M Ridlon
- Department of Animal Sciences, Division of Nutritional Sciences, Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, IL, United States; Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, United States.
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