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Infant to Elder: Microbes Across the Lifespan (Poster Theater Flash Session 2)

(PTFS02-04-25) Resistant Starch Supplementation Enhances Gut Barrier Integrity in Estrogen Deficient Mice by Modulating the Gut Microbiota

Saturday, May 31, 2025
2:12 PM – 2:16 PM ET
Location: South Hall B (The Hub) - Poster Theater / Poster Board Number PT-4
Diversity in Nutrition Oral Competition for Early Career Investigators
Objectives: The study evaluated the effects of two types of resistant starch (i.e., retrograded, RS3 and chemically modified, RS4) on gut microbiota and gut barrier integrity in estrogen-deficient mice.

Methods: Three-month-old female C57BL/6 mice were injected (ip) with the ovotoxicant vinyl cyclohexene diepoxide (VCD, 160 mg/kg in sesame oil) or vehicle for 30 d and estrogen deficiency was confirmed by a vaginal smear. Mice were then randomized into three dietary treatment groups (n=15/group) in a 3 x 2 factorial design: control (AIN-93M), 5% (wt/wt) RS3 or RS4. After 16 wks of dietary intervention, fecal and tissue samples were collected. Estrogen deficiency was further confirmed with uterine weight and serum follicle-stimulating hormone (FSH). Cecal content gut microbiota was assessed via 16S rRNA gene sequencing. Gut integrity was assessed by analyzing jejunal gene expression of inflammatory markers (Tnfα), tight junction proteins (Tjp1, Clndn1), and antimicrobial peptides (Reg3b, Reg3g). Fecal short-chain fatty acids (SCFAs) were quantified by GC-FID. Data were analyzed using a 2-way ANOVA with estrogen status (VCD/vehicle) and diet as factors, followed by post hoc tests when p < 0.05.

Results: As expected in estrogen deficiency, uterine weights were significantly reduced and serum FSH concentrations were elevated in the VCD group compared to the vehicle group. A main diet effect was observed in bacterial β-diversity, with distinct clustering in RS3 and RS4 compared to the control diet. Both types of RS increased bacterial genera, Bifidobacterium, Dubosiella, and Bacteroides, and reduced Clostridium sensu_stricto_1. Similarly, a main diet effect was observed in jejunal gene expression and fecal SCFAs. Both RS groups enhanced Tjp1 and Clndn1 gene expression and increased fecal SCFAs but only RS3 significantly elevated Reg3g gene expression. A significant interaction effect was observed with jejunal Tnfα mRNA with VCD increasing gene expression in the control diet, lowest in the RS4 group, and no effect with RS3.

Conclusions: The study demonstrated that while estrogen deficiency induced gut inflammation, RS4 downregulated the inflammatory response. Both RS3 and RS4 promoted a shift toward a beneficial gut microbiota and enhanced the expression of genes involved in maintaining gut barrier integrity.

Funding Sources: B.K, Pass, Jim and Lyn Williams Professorship.