Probiotic Bifidobacterium species stimulate human SLC26A3 gene function and expression in intestinal epithelial cells

Abstract

SLC26A3, or downregulated in adenoma (DRA), plays a major role in mediating Cl(-) absorption in the mammalian intestine. Disturbances in DRA function and expression have been implicated in intestinal disorders such as congenital Cl(-) diarrhea and gut inflammation. We previously showed that an increase in DRA function and expression by Lactobacillus acidophilus and its culture supernatant (CS) might underlie antidiarrheal effects of this probiotic strain. However, the effects of Bifidobacterium species, important inhabitants of the human colon, on intestinal Cl(-)/HCO3 (-) exchange activity are not known. Our current results demonstrate that CS derived from Bifidobacterium breve, Bifidobacterium infantis, and Bifidobacterium bifidum increased anion exchange activity in Caco-2 cells (∼1.8- to 2.4-fold). Consistent with the increase in DRA function, CS also increased the protein, as well as the mRNA, level of DRA (but not putative anion transporter 1). CS of all three Bifidobacterium sp. increased DRA promoter activity (-1,183/+114 bp) in Caco-2 cells (1.5- to 1.8-fold). Furthermore, the increase in DRA mRNA expression by CS of B. breve and B. infantis was blocked in the presence of the transcription inhibitor actinomycin D (5 μM) and the ERK1/2 MAPK pathway inhibitor U0126 (10 μM). Administration of live B. breve, B. infantis, and B. bifidum by oral gavage to mice for 24 h increased DRA mRNA and protein levels in the colon. These data demonstrate an upregulation of DRA via activation of the ERK1/2 pathway that may underlie potential antidiarrheal effects of Bifidobacterium sp.

The role of intestinal oxalate transport in hyperoxaluria and the formation of kidney stones in animals and man

“…Thus, the reductions in urinary oxalate in animals colonized with B. animalis occurred solely by intraluminal oxalate degradation. It is notable here that Kumar et al [176] looked at three other strains of Bifidobacteria and reported an increased expression of DRA in both mice and Caco-2 cells. This work focused on Cl − uptake by Caco-2 monolayers using a surrogate tracer ( 125 I) to show an approximate twofold induction of DRA function, although we saw no clear changes to the DRA-mediated absorptive oxalate flux, $J_{\mathrm{ms}}^{\mathrm{Ox}}$ [175].…”

Keratin 8 knockdown leads to loss of the chloride transporter DRA in the colon

“…DRA mRNA and protein levels can be upregulated in response to anti-inflammatory agents, such as butyrate and probiotics (Lactobacillus acidophilus, Bifidobacterium sp.) (1,19,29), suggesting that the microflora, which is more abundant in the proximal colon, may have played a role. To this end, broad-spectrum antibiotic treatment normalizes the K8 Ϫ/Ϫ colitis (11).…”

“…Gene specific primers used are listed in Table 1. Gene expression levels were normalized to GAPDH (19).…”

125Iodide as a surrogate tracer for epithelial chloride transport by the mouse large intestine in vitro

“…This price gap has greatly expanded, and 125 I − is now >1/500th the cost of 36 Cl − . More recently, 125 I − has been used to measure Cl − –HCO 3 − exchange activity and Cl − absorption by cultured Caco‐2 cells (Gujral et al., ; Kravtsov et al., ; Kumar et al., ) and everted gut sacs of mouse large intestine (Saksena et al., ), respectively. However, neither reported a direct comparison of I − with Cl − and, although the latter study was the first instance in which 125 I − was used to examine Cl − transport by epithelia, it presented only a single unidirectional flux.…”