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Abstract
Homeostasis is a prerequisite for health. When homeostasis becomes disrupted, dysfunction occurs. This is especially the case for the gut microbiota, which under normal conditions lives in symbiosis with the host. As there are as many microbial cells in and on our body as human cells, it is unlikely they would not contribute to health or disease. The gut bacterial metabolism generates numerous beneficial metabolites but also uremic toxins and their precursors, which are transported into the circulation. Barrier function in the intestine, the heart, and the kidneys regulates metabolite transport and concentration and plays a role in inter-organ and inter-organism communication via small molecules. This communication is analyzed from the perspective of the remote sensing and signaling theory, which emphasizes the role of a large network of multispecific, oligospecific, and monospecific transporters and enzymes in regulating small-molecule homeostasis. The theory provides a systems biology framework for understanding organ cross talk and microbe-host communication involving metabolites, signaling molecules, nutrients, antioxidants, and uremic toxins. This remote small-molecule communication is critical for maintenance of homeostasis along the gut-heart-kidney axis and for responding to homeostatic perturbations. Chronic kidney disease is characterized by gut dysbiosis and accumulation of toxic metabolites. This slowly impacts the body, affecting the cardiovascular system and contributing to the progression of kidney dysfunction, which in its turn influences the gut microbiota. Preserving gut homeostasis and barrier functions or restoring gut dysbiosis and dysfunction could be a minimally invasive way to improve patient outcomes and quality of life in many diseases, including cardiovascular and kidney disease.
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Affiliation(s)
- Griet Glorieux
- Nephrology Unit, Department of Internal Medicine and Pediatrics, Ghent University Hospital, Gent, Belgium (G.G., R.V., F.V.)
| | - Sanjay K Nigam
- Department of Pediatrics (S.K.N.), University of California San Diego, La Jolla, CA
- Division of Nephrology, Department of Medicine (S.K.N.), University of California San Diego, La Jolla, CA
| | - Raymond Vanholder
- Nephrology Unit, Department of Internal Medicine and Pediatrics, Ghent University Hospital, Gent, Belgium (G.G., R.V., F.V.)
| | - Francis Verbeke
- Nephrology Unit, Department of Internal Medicine and Pediatrics, Ghent University Hospital, Gent, Belgium (G.G., R.V., F.V.)
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Chaves LD, Abyad S, Honan AM, Bryniarski MA, McSkimming DI, Stahura CM, Wells SC, Ruszaj DM, Morris ME, Quigg RJ, Yacoub R. Unconjugated p-cresol activates macrophage macropinocytosis leading to increased LDL uptake. JCI Insight 2021; 6:144410. [PMID: 33914709 PMCID: PMC8262368 DOI: 10.1172/jci.insight.144410] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 04/28/2021] [Indexed: 01/03/2023] Open
Abstract
Patients with chronic kidney disease (CKD) and end-stage renal disease suffer from increased cardiovascular events and cardiac mortality. Prior studies have demonstrated that a portion of this enhanced risk can be attributed to the accumulation of microbiota-derived toxic metabolites, with most studies focusing on the sulfonated form of p-cresol (PCS). However, unconjugated p-cresol (uPC) itself was never assessed due to rapid and extensive first-pass metabolism that results in negligible serum concentrations of uPC. These reports thus failed to consider the host exposure to uPC prior to hepatic metabolism. In the current study, not only did we measure the effect of altering the intestinal microbiota on lipid accumulation in coronary arteries, but we also examined macrophage lipid uptake and handling pathways in response to uPC. We found that atherosclerosis-prone mice fed a high-fat diet exhibited significantly higher coronary artery lipid deposits upon receiving fecal material from CKD mice. Furthermore, treatment with uPC increased total cholesterol, triglycerides, and hepatic and aortic fatty deposits in non-CKD mice. Studies employing an in vitro macrophage model demonstrated that uPC exposure increased apoptosis whereas PCS did not. Additionally, uPC exhibited higher potency than PCS to stimulate LDL uptake and only uPC induced endocytosis- and pinocytosis-related genes. Pharmacological inhibition of varying cholesterol influx and efflux systems indicated that uPC increased macrophage LDL uptake by activating macropinocytosis. Overall, these findings indicate that uPC itself had a distinct effect on macrophage biology that might have contributed to increased cardiovascular risk in patients with CKD.
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Affiliation(s)
- Lee D Chaves
- Department of Medicine, Division of Nephrology, Jacobs School of Medicine and Biomedical Sciences, and.,Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, Buffalo, New York, USA
| | - Sham Abyad
- Department of Medicine, Division of Nephrology, Jacobs School of Medicine and Biomedical Sciences, and
| | - Amanda M Honan
- Department of Medicine, Division of Nephrology, Jacobs School of Medicine and Biomedical Sciences, and
| | - Mark A Bryniarski
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, Buffalo, New York, USA
| | - Daniel I McSkimming
- Department of Medicine, Bioinformatics and Computational Biology Core, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Corrine M Stahura
- Department of Medicine, Division of Nephrology, Jacobs School of Medicine and Biomedical Sciences, and
| | - Steven C Wells
- Department of Medicine, Division of Nephrology, Jacobs School of Medicine and Biomedical Sciences, and
| | - Donna M Ruszaj
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, Buffalo, New York, USA
| | - Marilyn E Morris
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, Buffalo, New York, USA
| | - Richard J Quigg
- Department of Medicine, Division of Nephrology, Jacobs School of Medicine and Biomedical Sciences, and
| | - Rabi Yacoub
- Department of Medicine, Division of Nephrology, Jacobs School of Medicine and Biomedical Sciences, and
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