Current Knowledge and Future Research Directions on Fecal Bacterial Patterns and Their Association with Asthma

Bacteroides thetaiotaomicron Ameliorates Experimental Allergic Airway Inflammation via Activation of ICOS+Tregs and Inhibition of Th2 Response

Inhibition of allergic airway diseases (AAD) by immunomodulation of the adaptive immune system through restoration of the enteric dysbiosis is an emerging therapeutic strategy. Patients with allergic rhinitis (n = 6) and healthy controls (n = 6) were enrolled, and gut microbiome composition analysis was performed by 16S rDNA sequencing. We also established an ovalbumin (OVA)-induced allergic airway inflammation murine model. Dysbiosis of the gut flora was observed in both AAD patients and the mice, with the decrease of the biodiversity and the quantity of the Bacteroidetes phylum. Oral application of Bacteroides (B.) thetaiotaomicron ameliorated the symptoms of OVA-induced airway hyperresponsiveness (AHR) and attenuated the airway inflammation in mice. In addition, nasal lavage fluid (NALF) and bronchoalveolar lavage fluid (BALF) from AAD mice orally administered with B. thetaiotaomicron showed reduced numbers of immune cells, and diminished secretion of T helper (Th)-2 cytokines (IL-4, IL-5, and IL-13) compared with the corresponding control mice, whereas the levels of Th1 cytokineIFN-γ was not changed in both the groups. When B. thetaiotaomicron was co-administered with metronidazole in AAD mice, the immunomodulatory effect was weakened and the allergic inflammatory response was aggravated. The ratios of CD4⁺Foxp3⁺ cells, CD4⁺ICOS⁺ T cells, CD4⁺ICOS⁺ Foxp3⁺ regulatory T cells, and IL-10-expressing CD4⁺Foxp3⁺ cells were increased in lymphocytes of spleen, mesenteric, and cervical lymph nodes of AAD mice administrated with B. thetaiotaomicron. Therefore, our data indicate that oral administration of B. thetaiotaomicron effectively inhibited the development of AAD in murine model; inhibition was mediated by the activation of Tregs and inhibition of Th2 response without promoting a Th1 response.

Incidence of irritable bowel syndrome and chronic fatigue following GI infection: a population-level study using routinely collected claims data

OBJECTIVES

To investigate the occurrence of postinfectious IBS in routine outpatient care, comparing different types of GI infection and its interaction with psychosomatic comorbidity.

DESIGN

Retrospective cohort study using routinely collected claims data covering statutorily insured patients in Bavaria, Germany. Cases were defined as patients without prior record of functional intestinal disorder with a first-time diagnosis of GI infection between January 2005 and December 2013 and classed according to the type of infection. Each case was matched by age, sex and district of residence to a patient without history of GI infection. Prior psychological disorder (depression, anxiety or stress reaction disorder) was assessed in the 2 years prior to inclusion. Proportional hazards regression models were used to estimate the HRs for GI infection and psychological disorder. Chronic fatigue syndrome (CFS) was assessed as a comparator outcome.

RESULTS

A total of 508 278 patients with first diagnosis of GI infection were identified, resulting in a matched cohort of 1 016 556 patients. All infection types were associated with an increased risk of IBS (HR: 2.19-4.25) and CFS (HR 1.35-1.82). Prior psychological disorder was a distinct risk factor for IBS (HR: 1.73) and CFS (HR: 2.08). Female sex was a further risk factor for both conditions.

CONCLUSION

Psychological disorder and GI infections are distinct risk factors for IBS. The high incidence of non-specific GI infection suggests that postinfectious IBS is a common clinical occurrence in primary care. Chronic fatigue is a further significant sequela of GI infection.

Fecal microbiome composition and stability in 4- to 8-year old children is associated with dietary patterns and nutrient intake

How long-term dietary intake shapes microbiota composition and stability in young children is poorly understood. Herein, the temporal variability in stool microbiota composition in relation to habitual dietary patterns of 4- to 8-year-old children (n=22) was investigated. Fecal samples were collected at baseline, 6 weeks and 6 months. Bacterial composition and volatile fatty acids were assessed by 16S rRNA sequencing and gas-chromatography, respectively. Nutrient intake was assessed using 3-day food diaries and dietary patterns were empirically derived from a food frequency questionnaire. Using a factor loading of >0.45 for a food group to be a major contributor to the overall dietary pattern, two dietary patterns were found to be associated with distinct microbiome composition. Dietary Pattern 1 (DP1), characterized by intake of fish, protein foods, refined carbohydrates, vegetables, fruit, juice and sweetened beverages, kid's meals and snacks and sweets, was associated with higher relative abundance of Bacteroidetes, Bacteroides and Ruminococcus and lower abundance of Bifidobacterium, Prevotella, Blautia and Roseburia. Dietary Pattern 2 (DP2), characterized by intake of grains, dairy and legumes, nuts and seeds, was associated with higher relative abundance of Cyanobacteria and Phascolarctobacterium and lower abundance of Dorea and Eubacterium. Fruit and starchy foods were present in both patterns, but were more associated with DP1 and DP2, respectively. Temporal stability of microbiota over a 6-month period was associated with baseline dietary patterns. Understanding how dietary intake contributes to microbiota composition and stability in early life in important for dietary recommendations and designing clinical interventions for microbiota-associated diseases.

Insect Bite Hypersensitivity in Horses is Associated with Airway Hyperreactivity

Background

Genetic and epidemiologic evidence suggests that in horses, as in other species, different manifestations of hypersensitivity may occur together.

Hypothesis

Horses affected with insect bite hypersensitivity (IBH) show airway hyperreactivity (AH) to inhaled histamine, even in the absence of overt clinical signs of equine asthma (EA).

Animals

Twenty‐two healthy controls (group C), 24 horses suffering from IBH alone (group IBH), and 23 horses suffering from IBH and EA (group IBH/EA).

Methods

The clinical histories were assessed using 2 standardized questionnaires, the Horse Owner Assessed Respiratory Signs Index (HOARSI), and IBH scoring. Horses were classified as EA‐affected if their HOARSI was >1 and as IBH‐affected if IBH score was >0. Confounding disorders were excluded by clinical examination. The arterial partial pressure of oxygen (PaO₂) was measured and flowmetric plethysmography used to assess airway reactivity to increasing doses of inhaled histamine.

Results

The median histamine provocation concentration (PC) when ∆_flow values increased by 35% (PC35) was significantly higher in group C (5.94 [1.11–26.33] mg/mL) compared to group IBH (2.95 [0.23–10.13] mg/mL) and group IBH/EA (2.03 [0.43–10.94] mg/mL; P < 0.01). The PC50 and PC75 showed very similar differences between groups. Furthermore, PaO₂ was significantly lower in group IBH (84 ± 8 mmHg) and group IBH/EA (78 ± 11 mmHg) compared to group C (89 ± 6 mmHg; P < 0.01).

Conclusions and Clinical Importance

IBH is associated with AH and decreased PaO₂, even in the absence of overt respiratory clinical signs.

Molecular pathological epidemiology: new developing frontiers of big data science to study etiologies and pathogenesis

Molecular pathological epidemiology (MPE) is an integrative field that utilizes molecular pathology to incorporate interpersonal heterogeneity of a disease process into epidemiology. In each individual, the development and progression of a disease are determined by a unique combination of exogenous and endogenous factors, resulting in different molecular and pathological subtypes of the disease. Based on "the unique disease principle," the primary aim of MPE is to uncover an interactive relationship between a specific environmental exposure and disease subtypes in determining disease incidence and mortality. This MPE approach can provide etiologic and pathogenic insights, potentially contributing to precision medicine for personalized prevention and treatment. Although breast, prostate, lung, and colorectal cancers have been among the most commonly studied diseases, the MPE approach can be used to study any disease. In addition to molecular features, host immune status and microbiome profile likely affect a disease process, and thus serve as informative biomarkers. As such, further integration of several disciplines into MPE has been achieved (e.g., pharmaco-MPE, immuno-MPE, and microbial MPE), to provide novel insights into underlying etiologic mechanisms. With the advent of high-throughput sequencing technologies, available genomic and epigenomic data have expanded dramatically. The MPE approach can also provide a specific risk estimate for each disease subgroup, thereby enhancing the impact of genome-wide association studies on public health. In this article, we present recent progress of MPE, and discuss the importance of accounting for the disease heterogeneity in the era of big-data health science and precision medicine.