Environmental factors and their impact on the intestinal microbiota: a role for human disease?

Development and large-scale production of human milk fat analog by fermentation of microalgae

Background

Human milk contains a complex mixture of triacylglycerols (TAG), making it challenging to recreate using common ingredients.

Objective

The study aimed to develop an innovative fermentation technique to produce essential human milk TAG, effectively tackling a significant hurdle in infant nutrition.

Method

An in-depth analysis of the literature has been conducted to identify the specific TAG to be targeted. We used a microalgal oil production platform and a two-step procedure to modify its fatty acid and TAG composition. The palmitic acid (16:0) content has been increased by classical strain improvement techniques, followed by a step involving the expression of a lysophosphatidic acid acyltransferase (LPAAT) sequence capable of esterifying 16:0 specifically at the internal position (sn-2 palmitate) of TAG. Once the strain was stabilized, the fermentation was scaled up in a 50-L reactor to yield several kilograms of biomass. Subsequently, the oil was extracted and refined using standard oil processing conditions. Liquid chromatography-mass spectrometry was employed to monitor the TAG profile and the region specificity of 16:0 at the internal position (sn-2 palmitate) of TAG.

Results

The initial strain had a 16:0 level of 25% of total fatty acids, which was increased to 30% by classical strain improvement. Simultaneously, the oleic acid level decreased from 61% to 57% of total fatty acids. Upon expression of an exogenous LPAAT gene, the level of the 16:0 esterified in the internal position of the TAG (sn-2 palmitate) increased by a factor of 10, to reach 73% of total palmitic acid. Consequently, the concentration of oleic acid in the internal position decreased from 81% to 22% of total fatty acids, with TAG analysis confirming that the primary TAG species in the oil was 1,3-dioleoyl-2-palmitoyl-glycerol (OPO). The 50-L-scale fermentation trial confirmed the strain's ability to produce oil with a yield of >150 g of oil per liter of fermentation broth in a timeframe of 5 days, rendering the process scalable for larger-scale industrialization.

Conclusion

We have demonstrated the feasibility of producing a suitable TAG composition that can be effectively integrated into the formulations of infant nutrition in combination with other fats and oils to meet the infant feeding requirements.

Characteristics of the Gut Microbiome of Healthy Young Male Soldiers in South Korea: The Effects of Smoking

Background/Aims

South Korean soldiers are exposed to similar environmental factors. In this study, we sought to evaluate the gut microbiome of healthy young male soldiers (HYMS) and to identify the primary factors influencing the microbiome composition.

Methods

We prospectively collected stool from 100 HYMS and performed next-generation sequencing of the 16S rRNA genes of fecal bacteria. Clinical data, including data relating to the diet, smoking, drinking, and exercise, were collected.

Results

The relative abundances of the bacterial phyla Firmicutes, Actinobacteria, Bacteroidetes, and Proteobacteria were 72.3%, 14.5%, 8.9%, and 4.0%, respectively. Fifteen species, most of which belonged to Firmicutes (87%), were detected in all examined subjects. Using cluster analysis, we found that the subjects could be divided into the two enterotypes based on the gut microbiome bacterial composition. Compared with enterotype 2 subjects, subjects classified as enterotype 1 tended to be characterized by higher frequencies of potentially harmful lifestyle habits (current smoker 55.6% vs 36.6%, p=0.222; heavy drinker 16.7% vs 3.7%, p=0.120; insufficient physical activity 27.8% vs 14.6%, p=0.318). We identified a significant difference in the microbiome compositions of current and noncurrent smokers (p=0.008); the former differed from the latter mainly in a relatively lower abundance of Bifidobacterium species and a higher abundance of Negativicutes.

Conclusions

A high abundance of Actinobacteria and low abundance of Bacteroidetes were the main features distinguishing the gut microbiomes of HYMS, and current smokers could be differentiated from noncurrent smokers by their lower abundance of Bifidobacterium and higher abundance of Negativicutes.

Review article: impact of cigarette smoking on intestinal inflammation-direct and indirect mechanisms

BACKGROUND

The inflammatory bowel diseases, Crohn's disease and ulcerative colitis are related multifactorial diseases. Their pathogenesis is influenced by each individual's immune system, the environmental factors within exposome and genetic predisposition. Smoking habit is the single best-established environmental factor that influences disease phenotype, behaviour and response to therapy.

AIM

To assess current epidemiological, experimental and clinical evidence that may explain how smoking impacts on the pathogenesis of inflammatory bowel disease.

METHODS

A Medline search for 'cigarette smoking', in combination with terms including 'passive', 'second-hand', 'intestinal inflammation', 'Crohn's disease', 'ulcerative colitis', 'colitis'; 'intestinal epithelium', 'immune system', 'intestinal microbiota', 'tight junctions', 'mucus', 'goblet cells', 'Paneth cells', 'autophagy'; 'epigenetics', 'genes', 'DNA methylation', 'histones', 'short noncoding/long noncoding RNAs'; 'carbon monoxide/CO' and 'nitric oxide/NO' was performed.

RESULTS

Studies found evidence of direct and indirect effects of smoking on various parameters, including oxidative damage, impairment of intestinal barrier and immune cell function, epigenetic and microbiota composition changes, that contribute to the pathogenesis of inflammatory bowel disease.

CONCLUSIONS

Cigarette smoking promotes intestinal inflammation by affecting the function and interactions among intestinal epithelium, immune system and microbiota/microbiome.

Administration of the Hyper-immune Bovine Colostrum Extract IMM-124E Ameliorates Experimental Murine Colitis

BACKGROUND AND AIMS

Inflammatory bowel disease [IBD] is accompanied by lesions in the epithelial barrier, which allow translocation of bacterial products from the gut lumen to the host's circulation. IMM-124E is a colostrum-based product containing high levels of anti-E.coli-LPS IgG, and might limit exposure to bacterial endotoxins. Here, we investigated whether IMM-124E can ameliorate intestinal inflammation.

METHODS

Acute colitis was induced in WT C57Bl/6J mice by administration of 2.5% dextran sodium sulphate [DSS] for 7 days. T cell transfer colitis was induced via transfer of 0.5 x 106 naïve T cells into RAG2-/- C57Bl/6J mice. IMM-124E was administered daily by oral gavage, either preventively or therapeutically.

RESULTS

Treatment with IMM-124E significantly ameliorated colitis in acute DSS colitis and in T cell transfer colitis. Maximum anti-inflammatory effects were detected at an IMM-124E concentration of 100 mg/kg body weight, whereas 25 mg/kg and 500 mg/kg were less effective. Histology revealed reduced levels of infiltrating immune cells and less pronounced mucosal damage. Flow cytometry revealed reduced numbers of effector T helper cells in the intestine, whereas levels of regulatory T cells were enhanced. IMM-124E treatment reduced the DSS-induced increase of serum levels of lipopolysaccharide [LPS]-binding protein, indicating reduced systemic LPS exposure.

CONCLUSIONS

Our results demonstrate that oral treatment with IMM-124E significantly reduces intestinal inflammation, via decreasing the accumulation of pathogenic T cells and concomitantly increasing the induction of regulatory T cells. Our study confirms the therapeutic efficacy of IMM-124E in acute colitis and suggests that administration of IMM-124E might represent a novel therapeutic strategy to induce or maintain remission in chronic colitis.

A study of the correlation between obesity and intestinal flora in school-age children

With the improvement of living standards and dietary changes, childhood obesity has increased worldwide. This study aimed to understand the differences of intestinal flora structure between obese and normal children at school-age. Using the next generation sequencing platform, Illumina Miseq, 16S rDNA high-throughput sequencing technology, we analyzed the diversity and relative abundance of intestinal flora in 39 obese and 38 normal control school-age children. First, we categorized gut bacteria on the basis of their Operational taxonomic units (OTUs) using the RDP 16s rRNA database in RDP classifier. The alpha (α) diversity was used to measure the diversity within a sample and is calculated as a value for each sample. The beta (β) diversity was used to compare different samples and to measure the dissimilarity between each other sample. Our results indicated that intestinal flora in obese children showed lower diversity than normal controls. Significant differences of relative abundance of intestinal flora were detected at multiple levels of classifications. Identification of intestinal flora with significant difference between obese and normal children may provide important information to uncover the roles of these specific bacteria in the development of obesity and find new strategy to prevent and treat obesity through intervening the intestinal flora.

Prevalence and Determinants of Job Stress in Patients with Inflammatory Bowel Disease

BACKGROUND

Psychosocial factors have been shown to predict a poor disease course in patients with inflammatory bowel disease (IBD), but whether this applies to job stress is currently unknown. We assessed the prevalence of job stress and its correlates in a large cohort of patients with IBD.

METHODS

We included all adult, professionally active patients enrolled between 2006 and 2015 in the Swiss IBD Cohort. Job stress was measured through the self-report effort-reward imbalance ratio and overcommitment (OC) to work questionnaires. We used multiple linear regressions to assess association with sociodemographic, lifestyle, psychosocial, and disease-related factors.

RESULTS

Altogether 1656 patients completed the questionnaires (905 Crohn's disease and 751 ulcerative colitis/IBD unclassified). Only 91 (5.7%) of patients had an effort-reward imbalance ratio >1. Effort-reward imbalance and OC scores were higher in full-time versus part-time employees (coef = 0.050, P = 0.002; coef = 0.906, P < 0.001) and among those absent from the workplace in the previous 3 months (coef = 0.049, P = 0.010; coef = 1.062, P < 0.001). Higher OC scores were associated with sex (women vs. men: coef = 0.568, P = 0.014), being in a relationship (coef = 0.805, P = 0.001), higher level of occupation (director vs. trainee: coef = 1.447, P < 0.001), and extraintestinal manifestations (coef = 0.623, P = 0.005). Patients hospitalized in the previous 12 months had lower OC scores (coef = 0.560, P = 0.038).

CONCLUSIONS

The average level of job stress seems to be remarkably low in patients with IBD from Switzerland. The clinician should turn attention especially to women, full-time employees with a high level of education, and patients with extraintestinal manifestations to identify those with the most vulnerability to suffer from job stress.

Beta-palmitate - a natural component of human milk in supplemental milk formulas

The composition and function of human milk is unique and gives a basis for the development of modern artificial milk formulas that can provide an appropriate substitute for non-breastfed infants. Although human milk is not fully substitutable, modern milk formulas are attempting to mimic human milk and partially substitute its complex biological positive effects on infants. Besides the immunomodulatory factors from human milk, research has been focused on the composition and structure of human milk fat with a high content of β-palmitic acid (sn-2 palmitic acid, β-palmitate). According to the available studies, increasing the content of β-palmitate added to milk formulas promotes several beneficial physiological functions. β-palmitate positively influences fatty acid metabolism, increases calcium absorption, improves bone matrix quality and the stool consistency, and has a positive effect on the development of the intestinal microbiome.