Soil intake modifies the gut microbiota and alleviates Th2-type immune response in an ovalbumin-induced asthma mouse model.

Background: A low-clean living environment (LCLE) can increase gut microbial diversity and prevent allergic diseases, whereas gut microbial dysbiosis is closely related to the pathogenesis of asthma. Our previous studies suggested that soil in the LCLE is a key factor in shaping intestinal microbiota. We aimed to explore whether sterilized soil intake as a prebiotic while being incubated with microbes in the air can attenuate mouse asthma inflammation by modifying gut microbiota. Methods: 16S rRNA gene sequencing was used to analyze the gut microbial composition, in combination with immune parameters measured in the lung and serum samples. Results: 16S rRNA gene sequencing results showed significant differences in the fecal microbiota composition between the test and control mice, with a higher abundance of Allobaculum, Alistipes, and Lachnospiraceae_UCG-001, which produce short-chain fatty acids and are beneficial for health in the test mice. Soil intake significantly downregulated the concentrations of IL-4 and IL-9 in serum and increased the expression of IFN-γ, which regulated the Th1/Th2 balance in the lung by polarizing the immune system toward Th1, alleviating ovalbumin-induced asthma inflammation. The effect of sensitization on gut microbiota was greater than that of air microbes and age together but weaker than that of soil. Conclusions: Soil intake effectively reduced the expression of inflammatory cytokines in asthmatic mice, possibly by promoting the growth of multiple beneficial bacteria. The results indicated that the development of soil-based prebiotic products might be used for allergic asthma management, and our study provides further evidence for the hygiene hypothesis.

Sterile soil mitigates the intergenerational loss of gut microbial diversity and anxiety-like behavior induced by antibiotics in mice.

The decline in gut microbial diversity in modern humans is closely associated with the rising prevalence of various diseases. It is imperative to investigate the underlying causes of gut microbial loss and restoring methods. Although the impact of non-perinatal antibiotic use on gut microbiota has been recognized, its intergenerational effects remain unexplored. Our previous research has highlighted soil in the farm environment as a key factor for gut microbiome health by restoring gut microbial diversity and balance. In this study, we investigated the intergenerational consequences of antibiotic exposure and the therapeutic potential of sterile soil. We treated C57BL/6 mice with vancomycin and streptomycin for 2 weeks continuously, followed by a 4-8 week withdrawal period before breeding. The process was repeated across 3 generations. Half of the mice in each generation received an oral sterile soil intervention. We assessed gut microbial diversity, anxiety behavior, microglial reactivity, and gut barrier integrity across generations. Antibiotic exposure led to a decrease in gut microbial diversity over generations, along with aggravated anxiety behavior, microgliosis, and altered intestinal tight junction protein expression. Oral sterile soil intervention restored gut microbial diversity in adult mice across generations, concomitantly rescuing abnormalities in behavior, microgliosis, and intestinal barrier integrity. In conclusion, this study simulated an important process of the progressive loss of gut microbiota diversity in modern humans and demonstrated the potential of sterile soil to reverse this process. This study provides a theoretical and experimental basis for research and interventions targeting multiple modern chronic diseases related to intestinal microorganisms.

Soil causes gut microbiota to flourish and total serum IgE levels to decrease in mice.

Traditional farm environments induce protection from allergic diseases. In this study, farm environmental factors were classified into three categories, environmental microbes, soil, and organic matter. To explore the impact of soil and environmental microorganisms on gut microbiota and immune function, mice were fed sterilized soil and inhaling microbes, soil microbes, or non-sterilized soil. Metagenomic sequencing results showed the intake of sterile soil, that is, inhaling a small amount of soil microbes in the air increased gut microbial diversity and the abundance of type III secretion system (T3SS) genes, and decreased serum immune IgE levels induced by 2-4-dinitrofluorobenzene (DNFB). The intake of soil microbes increased the abundance of genes involved in the metabolism of short-chain fatty acids and amino acid biosynthesis. Meanwhile, the intake of soil increased gut microbial diversity, the abundance of T3SS genes and related infectious elements, and genes associated with the metabolism of short-chain fatty acids and amino acid biosynthesis, and decreased serum IgE levels. Therefore, soil may be useful as a potential 'prebiotic' promoting the reproduction and growth of some intestinal microorganisms that harbour bacterial secretion system genes, especially those of T3SS, whose abundance was positively and significantly correlated with innate immune function of mice.

Soil exposure accelerates recovery of the gut microbiota in antibiotic-treated mice.

Environmental exposure to low cleanliness prevents the occurrence of allergic diseases and increases the richness and diversity of the intestinal microbiota. Antibiotics are widely used in clinical infection therapy but destroy the balance of the gut microbiota. In this study, the effects of cleanliness of the living environment on the gut microbiota are evaluated after administration of antibiotics. The patterns of gut microbiota are compared before and after antibiotic treatment in mice living in a higher standard clean environment with those of mice living in an unclean environment. The results show that dust exposure prevents the reduction in gut microbiota diversity following antibiotic treatment in mice and impaired structural changes in the gut microbiota. Additionally, dust exposure accelerates the recovery of the gut microbiota, regardless of consumption of a high-fat or normal diet. An unsanitary environment can reduce the effects of antibiotics on intestinal microecology in mice. These findings provide insights into approaches for regulating antibiotic-induced symbiosis of the gut microbiota and preventing diseases.

Circulating APP, NCAM and Aß serve as biomarkers for Alzheimer's disease.

Alzheimer's disease (AD) is the most common neurodegenerative disease and the early diagnosis and intervention are important for valid treatment of AD. However, there are few biomarkers for the diagnosis and monitoring of AD. In the present study, circulating APP, NCAM, Aß40, and Aß42 were measured in order to identify which marker or combination of markers could be useful, cost-effective and noninvasive biomarkers for diagnosing and continuously monitoring AD. The results showed that circulating APP, NCAM, Aß40, and Aß42 were different between the AD group and the control group. Importantly, the combination of the four biomarkers had the highest AUC (0.997) with the highest sensitivity (98.5). Therefore, circulating APP, NCAM, Aß40, and Aß42 can be used as desirable biomarkers for AD diagnosis and monitoring.

Maximum cadmium limits establishment strategy based on the dietary exposure estimation: an example from Chinese populations and subgroups.

Dietary exposure to cadmium (Cd) in the Chinese population is currently a public health concern. China's national standard for maximum limits (MLs) of Cd in foods needs to be assessed. The objective of this research is to estimate the impacts of different Cd MLs intakes from selected foods and food groups and to provide scientific evidence for ML establishment. Food consumption data were taken from the Chinese National Diet and Nutrition Survey. Cd contamination data were obtained from the National Food Contamination Monitoring Program. A beta binomial normal (BBN) model was applied in the probabilistic assessment. Different possible ML scenarios for rice were selected to assess the impact of different MLs on Cd concentration and intake. More than 70% of children aged 2-6 years and over 30% of the general population have a dietary daily Cd intake above provisional tolerable daily intake (PTMId). Cd intake changed greatly relative to baseline when different possible MLs were used, but the changes were not as large when compared among the different possible MLs. Cd exposure in China, especially for children, is a public health concern. It is recommended that the ML for rice be held at 0.2 mg/kg.

Impact of Environmental Microbes on the Composition of the Gut Microbiota of Adult BALB/c Mice.

To investigate the impact of microbes within the living environment on the gut microbiota of adults, we raised three groups of BALB/c mice from 3-4 weeks age in the same specific-pathogen-free animal room for 8 weeks. The control group lived in cages with sterilized bedding (pelletized cardboard), the probiotics group had three probiotics added to the sterilized bedding, and the intestinal microbes (IM) group had the intestinal microbes of a healthy goat added to the bedding. All other variables such as diet, age, genetic background, physiological status, original gut microbiota, and living room were controlled. Using high-throughput sequencing of the 16S rRNA gene, we observed that the control and probiotics groups had similar diversity and richness of gut microbiota. The two groups had significantly lower diversity than the IM group. We also observed that the IM group had a specific structure of gut microbial community compared with the control and probiotics groups. However, the dominate bacteria changed slightly upon exposure to intestinal microbes, and the abundance of the non-dominate species changed significantly. In addition, exposure to intestinal microbes inhibited DNFB-induced elevation of serum IgE levels. Our results provide new evidence in support of the microflora and hygiene hypotheses.

Exposure to soil, house dust and decaying plants increases gut microbial diversity and decreases serum immunoglobulin E levels in BALB/c mice.

To assess the impact of sanitation of a living environment on gut microbiota and development of the immune system, we raised BALB/c mice under three distinct environmental conditions: a specific pathogen-free animal room (SPF), a general animal room (XZ) and a farmhouse (JD). All other variables like diet, age, genetic background, physiological status and original gut microbiota were controlled for in the three groups. Using high-throughput sequencing of the 16S rRNA gene, we found that each mouse group had a specific structure of the gut microbial community. Groups JD and XZ harboured a significantly more diverse and richer gut microbiota than did group SPF. Bacteroidetes were significantly more abundant in groups XZ and JD than in group SPF, whereas Firmicutes showed the inverse pattern. Total serum immunoglobulin E (IgE) levels were significantly lower in groups XZ and JD than in group SPF. There were no significant differences in gut microbiota diversity and serum IgE concentration between groups JD and XZ, but we found higher abundance of dominant genera in the gut microflora of group JD. We conclude that exposure to soil, house dust and decaying plant material enhances gut microbial diversity and innate immunity. Our results seem to provide new evidence supporting the hygiene hypothesis.