Triclosan has a robust, yet reversible impact on human gut microbial composition in vitro

The food additive butylated hydroxyanisole minimally affects the human gut microbiome ex vivo

Butylated hydroxyanisole (BHA) continues to raise consumer concerns. All previous evaluations of this additive have failed to consider its effect on the gut microbiome, even though it enters the colon. An ex vivo model was used to assess the effect of BHA on microbial communities from 24 donors, aged infants to older adults. A dose of 0.35 g/L BHA elicited no statistically significant changes in the functional outputs or community structure for any age group. Although not large enough to affect community diversity, there were some significant decreases at the phylum level. Among the genes most significantly affected by treatment with BHA across age groups are those involved in lipopolysaccharide synthesis and bacterial electron transport encoded by Bacteroidota, Proteobacteria, and Verrucomicrobiota. Given what is known about the intracellular activity of BHA, these genes may hint at a mechanism behind BHA's evident, but minimally detrimental effect on the gut microbiota.

Personalized nutrition studies of human gut microbiome-polyphenol interactions utilizing continuous multistaged in vitro fermentation models-a narrative review

The gut microbiota, a complex community of microorganisms primarily inhabiting the human large intestine, plays a crucial role in human health. Gut dysbiosis, characterized by an imbalance in gut bacterial populations, has been increasingly recognized as a significant factor in the pathogenesis of metabolic diseases such as type 2 diabetes, inflammatory bowel disease, and colorectal cancer. Polyphenols are critical modulators of gut microbial composition and metabolism. However, the extent of polyphenol-induced modulation of the gut microbiome remains largely unexplored. In vitro models offer a convenient and ethical alternative to in vivo studies for investigating nutrient-gut microbiome interactions, facilitating easy sampling and controlled experimental conditions. Among these, continuous multistaged in vitro fermentation models, which simulate different sections of the human gastrointestinal tract (e.g., proximal colon, transverse colon, and distal colon), provide a more accurate representation of the human gut environment compared to single-batch fermentation. Various configurations of these multistaged models have been developed and widely employed in studies examining the effects of polyphenols on the gut microbiome. This review aims to summarize the different configurations of multistaged in vitro fermentation models and recent advancements in their development, highlight key aspects of experimental design, outline commonly used analytical workflows with complementary analyses, and review the restorative effects of polyphenol interventions on dysregulated gut microbiota.

Interference Mechanisms of Endocrine System and Other Systems of Endocrine-Disrupting Chemicals in Cosmetics-In Vitro Studies

Endocrine-disrupting chemicals (EDCs), found in various cosmetic products, interfere with the normal functioning of the endocrine system, impacting hormone regulation and posing risks to human health. Common cosmetic EDCs, such as ultraviolet (UV) filters, parabens, and triclosan, can enter the human body through different routes, including skin absorption. Their presence has been linked to adverse effects on reproduction, immune function, and development. High-throughput in vitro assays, using various human cell lines, were employed to assess the effects of common cosmetic EDCs such as ethylhexyl methoxycinnamate (EHMC), benzophenone-3 (BP-3), homosalate, and parabens. Despite ongoing regulatory efforts, gaps persist in understanding their long-term impacts, particularly when they are present as mixtures or degradation products in the environment. This study focuses on recent in vitro research to investigate the mechanisms through which cosmetic-related EDCs disrupt the endocrine system and other physiological systems. The in vitro findings highlight the broader systemic impact of these chemicals, extending beyond the endocrine system to include immune, reproductive, and cardiovascular effects. This research underscores the importance of developing safer cosmetic formulations and enhancing public health protection, emphasizing the need for stricter regulations.

Supplementation with soluble or insoluble rice-bran fibers increases short-chain fatty acid producing bacteria in the gut microbiota in vitro

Introduction

Studies have shown that a diet high in fiber and prebiotics has a positive impact on human health due largely to the fermentation of these compounds by the gut microbiota. One underutilized source of fiber may be rice bran, a waste product of rice processing that is used most frequently as an additive to livestock feed but may be a good source of fibers and other phenolic compounds as a human diet supplement. Previous studies focused on specific compounds extracted from rice bran showed that soluble fibers extracted from rice bran can improve glucose response and reduce weight gain in mouse models. However, less is known about changes in the human gut microbiota in response to regular rice bran consumption.

Methods

In this study, we used a Simulator of the Human Intestinal Microbial Ecology (SHIME®) to cultivate the human gut microbiota of 3 different donors in conditions containing either soluble or insoluble fiber fractions from rice bran. Using 16S rRNA amplicon sequencing and targeted metabolomics via Gas Chromatography-Mass Spectrometry, we explored how gut microbial communities developed provided different supplemental fiber sources.

Results

We found that insoluble and soluble fiber fractions increased short-chain fatty acid production, indicating that both fractions were fermented. However, there were differences in response between donors, for example the gut microbiota from donor 1 increased acetic acid production with both fiber types compared with control; whereas for donors 2 and 3, butanoic acid production increased with ISF and SF supplementation. Both soluble and insoluble rice bran fractions increased the abundance of Bifidobacterium and Lachnospiraceae taxa.

Discussion

Overall, analysis of the effect of soluble and insoluble rice bran fractions on the human in vitro gut microbiota and the metabolites produced revealed individually variant responses to these prebiotics.

Impact of Ivermectin on the Gut Microbial Ecosystem

Ivermectin is a an anti-helminthic that is critical globally for both human and veterinary care. To the best of our knowledge, information available regarding the influence of ivermectin (IVM) on the gut microbiota has only been collected from diseased donors, who were treated with IVM alone or in combination with other medicines. Results thus obtained were influenced by multiple elements beyond IVM, such as disease, and other medical treatments. The research presented here investigated the impact of IVM on the gut microbial structure established in a Triple-SHIME® (simulator of the human intestinal microbial ecosystem), using fecal material from three healthy adults. The microbial communities were grown using three different culture media: standard SHIME media and SHIME media with either soluble or insoluble fiber added (control, SF, ISF). IVM introduced minor and temporary changes to the gut microbial community in terms of composition and metabolite production, as revealed by 16S rRNA amplicon sequencing analysis, flow cytometry, and GC-MS. Thus, it was concluded that IVM is not expected to induce dysbiosis or yield adverse effects if administered to healthy adults. In addition, the donor's starting community influences the relationship between IVM and the gut microbiome, and the soluble fiber component in feed could protect the gut microbiota from IVM; an increase in short-chain fatty acid production was predicted by PICRUSt2 and detected with IVM treatment.

Association of triclosan and human infertility: A systematic review

Triclosan (TCS) is a chemical compound, which has antibacterial, antiviral, and antifungal properties. TCS is considered an endocrine-disrupting chemical, which has been shown to interfere with developmental, behavioral, and reproductive outcomes in biological models and cell cultures. However, implications about exposure to TCS and human infertility are rare. Thus, the main of this review is summarize the available evidence of the association between triclosan exposure on human infertility. For this, systematic review was conducted following the recommendations established in Report of Systematic Reviews and Meta-Analyses guide (PRISMA). Initially, an electronic search in MEDLINE (via PubMed) and Science direct was performed. The methodological quality of the included studies was verified through the Joanna Briggs Institute (JBI) checklists. All selection and data extraction processes were carried out independently by two reviewers. The evidence was organized and presented using tables and narrative synthesis. There is lacking evidence about the association between triclosan and human infertility. Overall, no association between triclosan and infertility was found. However, semen quality and ovarian reserve are susceptible to triclosan exposure. Thus, future studies are still needed to better elucidate the associations between triclosan and infertility outcomes.

Lacticaseibacillus rhamnosus Strain GG (LGG) Regulate Gut Microbial Metabolites, an In Vitro Study Using Three Mature Human Gut Microbial Cultures in a Simulator of Human Intestinal Microbial Ecosystem (SHIME)

In the present research, we investigated changes in the gut metabolome that occurred in response to the administration of the Laticaseibacillus rhamnosus strain GG (LGG). The probiotics were added to the ascending colon region of mature microbial communities established in a human intestinal microbial ecosystem simulator. Shotgun metagenomic sequencing and metabolome analysis suggested that the changes in microbial community composition corresponded with changes to metabolic output, and we can infer linkages between some metabolites and microorganisms. The in vitro method permits a spatially-resolved view of metabolic transformations under human physiological conditions. By this method, we found that tryptophan and tyrosine were mainly produced in the ascending colon region, while their derivatives were detected in the transverse and descending regions, revealing sequential amino acid metabolic pathways along with the colonic tract. The addition of LGG appeared to promote the production of indole propionic acid, which is positively associated with human health. Furthermore, the microbial community responsible for the production of indole propionic acid may be broader than is currently known.

Dietary exposure to endocrine disruptors in gut microbiota: A systematic review

Endocrine disrupting chemicals (EDCs) can interfere with hormonal actions and have been associated with a higher incidence of metabolic disorders. They affect numerous physiological, biochemical, and endocrinal activities, including reproduction, metabolism, immunity, and behavior. The purpose of this review was to elucidate the association of EDCs in food with the gut microbiota and with metabolic disorders. EDC exposure induces changes that can lead to microbial dysbiosis. Products and by-products released by the microbial metabolism of EDCs can be taken up by the host. Changes in the composition of the microbiota and production of microbial metabolites may have a major impact on the host metabolism.

Modulation of the Gut Microbiota Structure and Function by Two Structurally Different Lemon Pectins

Pectins are plant polysaccharides consumed as part of a diet containing fruits and vegetables. Inside the gastrointestinal tract, pectin cannot be metabolized by the mammalian cells but is fermented by the gut microbiota in the colon with the subsequent release of end products including short-chain fatty acids (SCFA). The prebiotic effects of pectin have been previously evaluated but reports are inconsistent, most likely due to differences in the pectin chemical structure which can vary by molecular weight (MW) and degree of esterification (DE). Here, the effects of two different MW lemon pectins with varying DEs on the gut microbiota of two donors were evaluated in vitro. The results demonstrated that low MW, high DE lemon pectin (LMW-HDE) altered community structure in a donor-dependent manner, whereas high MW, low DE lemon pectin (HMW-LDE) increased taxa within Lachnospiraceae in both donors. LMW-HDE and HMW-LDE lemon pectins both increased total SCFAs (1.49- and 1.46-fold, respectively) and increased acetic acid by 1.64-fold. Additionally, LMW-HDE lemon pectin led to an average 1.41-fold increase in butanoic acid. Together, these data provide valuable information linking chemical structure of pectin to its effect on the gut microbiota structure and function, which is important to understanding its prebiotic potential.

Triclosan: A Small Molecule with Controversial Roles

Triclosan (TCS), a broad-spectrum antimicrobial agent, has been widely used in personal care products, medical products, plastic cutting boards, and food storage containers. Colgate Total® toothpaste, containing 10 mM TCS, is effective in controlling biofilm formation and maintaining gingival health. Given its broad usage, TCS is present ubiquitously in the environment. Given its strong lipophilicity and accumulation ability in organisms, it is potentially harmful to biohealth. Several reports suggest the toxicity of this compound, which is inserted in the class of endocrine disrupting chemicals (EDCs). In September 2016, TCS was banned by the U.S. Food and Drug Administration (FDA) and the European Union in soap products. Despite these problems, its application in personal care products within certain limits is still allowed. Today, it is still unclear whether TCS is truly toxic to mammals and the adverse effects of continuous, long-term, and low concentration exposure remain unknown. Indeed, some recent reports suggest the use of TCS as a repositioned drug for cancer treatment and cutaneous leishmaniasis. In this scenario it is necessary to investigate the advantages and disadvantages of TCS, to understand whether its use is advisable or not. This review intends to highlight the pros and cons that are associated with the use of TCS in humans.

Are silver nanoparticles better than triclosan as a daily antimicrobial? Answers from the perspectives of gut microbiome disruption and pathogenicity

As an alternative to triclosan (TCS), the widespread use of silver nanoparticles (AgNPs) in daily products shows genuine potential. However, information regarding whether AgNPs are substantially better than TCS in their potential disruption of the gut microbiome and health effects is lacking. Using a simulator of the human intestinal microbial ecosystem (SHIME), we systemically compared the effects of TCS and AgNPs (at 1 μg/L and 30 μg/L) on the human gut microbiome in terms of changes in gut homeostasis, microbial community structure, antibiotic resistance profiles and abundances of opportunistic pathogens. Generally, TCS exerted more severe effects than AgNPs on gut disturbances (i.e., decreased production of short-chain fatty acids, increased contents of ammonium and total bile acids, and increased β-glucosidase activities) in a dose-dependent manner, whereas no clear dose effect was observed for the AgNP treatment because of potential nanoparticle transformation. The more serious effect of TCS than AgNPs on the microbiota composition was indicated by the dynamic increase in the Firmicutes/Bacteroidetes ratio determined using 16S rDNA sequencing. Metagenomic analyses revealed a more pronounced effect of TCS than AgNPs on the selection and dissemination of multiple resistance genes to antibiotics, TCS, and even Ag via the enrichment of genes encoding efflux pumps and mobile genetic elements. Consequently, the overgrowth of opportunistic pathogens was observed upon TCS exposure due to an imbalanced microbiome, in contrast to a slight increase in the abundance of some beneficial bacteria (i.e., Bifidobacterium) induced by the AgNP treatment. In conclusion, from the perspective of effects on gut health, AgNPs may prevail over TCS to some extent. However, the stress and potential selection of Ag resistance indicates the need for targeted surveillance of AgNP commercialization for daily use.