Fisetin Improves Hyperuricemia-Induced Chronic Kidney Disease via Regulating Gut Microbiota-Mediated Tryptophan Metabolism and Aryl Hydrocarbon Receptor Activation

Hypertension and chronic kidney disease (CKD) can originate during early-life. Tryptophan metabolites generated by different pathways have both detrimental and beneficial effects. In CKD, uremic toxins from the tryptophan-generating metabolites are endogenous ligands of the aryl hydrocarbon receptor (AHR). The interplay between AHR, nitric oxide (NO), the renin–angiotensin system (RAS), and gut microbiota is involved in the development of hypertension. We examined whether tryptophan supplementation in pregnancy can prevent hypertension and kidney disease programmed by maternal CKD in adult offspring via the aforementioned mechanisms. Sprague–Dawley (SD) female rats received regular chow or chow supplemented with 0.5% adenine for 3 weeks to induce CKD before pregnancy. Pregnant controls or CKD rats received vehicle or tryptophan 200 mg/kg per day via oral gavage during pregnancy. Male offspring were divided into four groups (n = 8/group): control, CKD, tryptophan supplementation (Trp), and CKD plus tryptophan supplementation (CKDTrp). All rats were sacrificed at the age of 12 weeks. We found maternal CKD induced hypertension in adult offspring, which tryptophan supplementation prevented. Maternal CKD-induced hypertension is related to impaired NO bioavailability and non-classical RAS axis. Maternal CKD and tryptophan supplementation differentially shaped distinct gut microbiota profile in adult offspring. The protective effect of tryptophan supplementation against maternal CKD-induced programmed hypertension is relevant to alterations to several tryptophan-metabolizing microbes and AHR signaling pathway. Our findings support interplay among tryptophan-metabolizing microbiome, AHR, NO, and the RAS in hypertension of developmental origins. Furthermore, tryptophan supplementation in pregnancy could be a potential approach to prevent hypertension programmed by maternal CKD.

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Aryl Hydrocarbon Receptor and Uremic Toxins from the Gut Microbiota in Chronic Kidney Disease Patients: Is There a Relationship between Them?

Biochemistry ◽

10.1021/acs.biochem.8b01305 ◽

2019 ◽

Vol 58 (15) ◽

pp. 2054-2060 ◽

Cited By ~ 9

Author(s):

Jessyca Sousa de Brito ◽

Natália Alvarenga Borges ◽

Juliana Saraiva dos Anjos ◽

Lia Sumie Nakao ◽

Milena Barcza Stockler-Pinto ◽

...

Keyword(s):

Chronic Kidney Disease ◽

Kidney Disease ◽

Gut Microbiota ◽

Aryl Hydrocarbon Receptor ◽

Uremic Toxins ◽

Aryl Hydrocarbon

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A42 MICROBIAL METABOLISM OF DIETARY TRYPTOPHAN ENHANCES ARYL HYDROCARBON RECEPTOR ACTIVATION: IMPLICATIONS FOR IBD

Journal of the Canadian Association of Gastroenterology ◽

10.1093/jcag/gwz047.041 ◽

2020 ◽

Vol 3 (Supplement_1) ◽

pp. 50-51

Author(s):

L Rondeau ◽

A V Clarizio ◽

J Jury ◽

D L Gibson ◽

P Bercik ◽

...

Keyword(s):

16S Rrna ◽

Gut Microbiota ◽

Aryl Hydrocarbon Receptor ◽

Healthy Subjects ◽

Tryptophan Metabolism ◽

Luciferase Reporter ◽

Reporter Assay ◽

Aryl Hydrocarbon ◽

Deficient Mice ◽

Activation Capacity

Abstract Background Intestinal immune homeostasis is maintained by the interplay between microbiota and the mucosal immune system. Changes in gut microbiota have been associated with chronic intestinal conditions, such as inflammatory bowel disease (IBD). The aryl hydrocarbon receptor (AhR) is a transcription factor that is activated by dietary and environmental stimuli to control immune responses in the gut and homeostatic mechanisms at mucosal surfaces. In IBD, AhR expression is downregulated. Major agonists of AhR in the gut include microbial tryptophan metabolites such as indole derivatives, which are decreased in IBD patients. The mechanisms involved in tryptophan metabolism by bacteria and their implications in AhR activation and thus IBD pathogenesis are not well understood. Aims To investigate whether tryptophan metabolism by intestinal bacteria participates in AhR activation and IBD pathogenesis. Methods Microbiota profiles (16S rRNA Illumina) and activation of AhR (luciferase reporter assay) were determined in fecal samples from IBD patients (n=10) and healthy volunteers (n=10). Germ-free C57BL/6 mice were colonized with fecal slurries of 2 healthy subjects and 4 IBD patients (n=4 mice/donor) by oral gavage (humanized-mice). All mice were fed irradiated tryptophan diets with 0.1% or 1% tryptophan content for 14 days. Simultaneously, SPF Mucin 2 (Muc2) deficient mice (C57BL/6 background), which develop colitis spontaneously, were fed tryptophan diets (0.1%, 0.3% and 1% content). Activation of AhR was measured in feces using an AhR luciferase reporter assay. Inflammation was determined by immunohistochemistry and the characterization of immune infiltrate in colon cross-sections. Bacteria from human and mouse fecal samples were isolated and screened for their ability to produce indoles using biochemical reagents. Positive bacteria were identified by colony PCR and 16S rRNA Sanger sequencing. Results IBD patients had an altered fecal microbiota with a lower capacity to activate AhR compared to healthy subjects. Colonization of mice with microbiota from healthy subjects induced greater activation of AhR compared to mice colonized with microbiota from patients with IBD. Furthermore, increasing dietary tryptophan composition rescued the capacity to activate AhR. In Muc2 deficient mice, dietary tryptophan treatment enhanced AhR activation capacity and reduced infiltration of innate immune cells before the onset of colitis. Several AhR agonist producing bacterial species were identified and will be used in future experiments. Conclusions Activation of AhR is dependent on the gut microbiota and disease status of the donor. Dietary intervention with tryptophan enhances AhR activation capacity and may be a potential therapeutic avenue in IBD individuals with intestinal dysbiosis. Funding Agencies Farncombe Family Digestive Health Research Institute, Biocodex Microbiota Foundation

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