Uremia-Induced Gut Barrier Defect in 5/6 Nephrectomized Mice Is Worsened by Candida Administration through a Synergy of Uremic Toxin, Lipopolysaccharide, and (1➔3)-β-D-Glucan, but Is Attenuated by Lacticaseibacillus rhamnosus L34

Abstract

A chronic kidney disease (CKD) causes uremic toxin accumulation and gut dysbiosis, which further induces gut leakage and worsening CKD. Lipopolysaccharide (LPS) of Gram-negative bacteria and (1➔3)-β-D-glucan (BG) of fungi are the two most abundant gut microbial molecules. Due to limited data on the impact of intestinal fungi in CKD mouse models, the influences of gut fungi and Lacticaseibacillus rhamnosus L34 (L34) on CKD were investigated using oral C. albicans-administered 5/6 nephrectomy (5/6Nx) mice. At 16 weeks post-5/6Nx, Candida-5/6Nx mice demonstrated an increase in proteinuria, serum BG, serum cytokines (tumor necrotic factor-α; TNF-α and interleukin-6), alanine transaminase (ALT), and level of fecal dysbiosis (Proteobacteria on fecal microbiome) when compared to non-Candida-5/6Nx. However, serum creatinine, renal fibrosis, or gut barrier defect (FITC-dextran assay and endotoxemia) remained comparable between Candida- versus non-Candida-5/6Nx. The probiotics L34 attenuated several parameters in Candida-5/6Nx mice, including fecal dysbiosis (Proteobacteria and Bacteroides), gut leakage (fluorescein isothiocyanate (FITC)-dextran), gut-derived uremic toxin (trimethylamine-N-oxide; TMAO) and indoxyl sulfate; IS), cytokines, and ALT. In vitro, IS combined with LPS with or without BG enhanced the injury on Caco-2 enterocytes (transepithelial electrical resistance and FITC-dextran permeability) and bone marrow-derived macrophages (supernatant cytokines (TNF-α and interleukin-1 β; IL-1β) and inflammatory genes (TNF-α, IL-1β, aryl hydrocarbon receptor, and nuclear factor-κB)), compared with non-IS activation. These injuries were attenuated by the probiotics condition media. In conclusion, Candida administration worsens kidney damage in 5/6Nx mice through systemic inflammation, partly from gut dysbiosis-induced uremic toxins, which were attenuated by the probiotics. The additive effects on cell injury from uremic toxin (IS) and microbial molecules (LPS and BG) on enterocytes and macrophages might be an important underlying mechanism.

Candida Administration in 5/6 Nephrectomized Mice Enhanced Fibrosis in Internal Organs: An Impact of Lipopolysaccharide and (1→3)-β-D-Glucan from Leaky Gut

“…Oral Candida administration in mice is used to examine the influence of gut fungi in several models, taking advantage of the lower abundance of C. albicans in mouse feces compared with humans (Candida in mouse feces is detectable only by polymerase chain reaction (PCR) [50], but not by culture methods [11], which differs from human conditions [12]. Here, Candida-5/6 Nx mice had more severe gut leakage (FITC-dextran assay), with a higher level of serum endotoxin and BG (glucanemia) compared to non-Candida 5/6 Nx mice, perhaps due to the direct intestinal invasion of fungi, gut dysbiosis, and proinflammatory enterocytes [18]. Although enterocytes are naturally resistant to pathogen molecules (LPS and BG), the presence of certain uremic toxins enhances the inflammatory responses in Caco-2 cells (an enterocyte cell line), which might cause a leaky gut [42].…”

“…For kidney fibrosis, there are only a few investigations on the impact of gut fungi and BG on CKD. As such, our previous publication demonstrates no difference in renal fibrosis between in CKD mice with or without Candida gavage at 16 weeks after 5/6 nephrectomy (5/6 Nx), despite a synergistic pro-inflammatory effect of LPS plus BG [18]. However, the pro-fibrotic impact of LPS and BG on other organs, and the influence on the kidney after extended observation, might be different.…”

“…Although the presence of Candida spp. in the gut does not directly cause disease, gut fungi alter the gut microbiota and provide a higher BG in gut content [13], which possibly worsens systemic inflammation following a gut barrier malfunction (gut leakage) through the systemic immune responses against BG [14][15][16][17][18][19][20]. Indeed, the possible fungal mechanisms that interfere with the growth of specific bacteria (mostly the lower virulence) in the gut are mentioned, including some bactericidal molecules (yeast killer toxins, Candida exotoxin, and endogenous alcohol) [21][22][23][24], and the competition for certain nutrients [25].…”

Helicobacter pylori, Protected from Antibiotics and Stresses Inside Candida albicans Vacuoles, Cause Gastritis in Mice

“…Moreover, (1, 3)-beta-D-glucan (BG), the major polysaccharide component in the yeast cell wall that is released during the growth and death of fungi [ 22 ], is one of the important pathogen-associated molecular patterns (PAMPs) that can enhance pro-inflammatory effects through macrophage and neutrophil stimulation [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. Unsurprisingly, the oral administration of C. albicans enhances systemic inflammation and disease severity in several models through the activation of BG against innate immunity [ 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. Despite the intensive study of bacterial–fungal interaction, especially Candida spp., in respiratory systems and catheter infections [ 38 , 39 ], there are few data on Candida –bacterial interactions in the stomach.…”

Bacteroides plebeius improves muscle wasting in chronic kidney disease by modulating the gut‐renal muscle axis

“…In particular, two uremic toxins, indoxyl sulfate (IS) and LPS, are produced via fermentation by proteolytic bacteria in the gut and accumulate in the gut due to decreased glomerular filtration and reduced proximal tubular secretion. 28 IS has been shown to be associated with aortic calcification and vascular smooth muscle cell proliferation in both rats and humans. 29 Studies have shown that LPS can upregulate the expression of atrogin‐1 and MuRF1 by increasing the activity of NF‐κB and its downstream inflammatory mediators, such as TNF‐α, IL‐1β or the NLR family pyrin domains.…”