The Hygiene Hypothesis in the Age of the Microbiome

The diversity of the microbiome impacts chronic lymphocytic leukemia development in mice and humans

The gut microbiota plays a critical role in maintaining a healthy human body and its dysregulation is associated with various diseases. In this study, we investigated the influence of gut microbiome diversity on the development of chronic lymphocytic leukemia (CLL). Analysis of stool samples from 59 CLL patients revealed individual and heterogeneous microbiome compositions, but allowed for grouping of patients according to their microbiome diversity. Interestingly, CLL patients with lower microbiome diversity and an enrichment of bacteria linked to poor health suffered from a more advanced or aggressive form of CLL. In the Eµ-TCL1 mouse model of CLL, we observed a faster course of disease when mice were housed in high hygiene conditions. Shotgun DNA sequencing of fecal samples showed that this was associated with a lower microbiome diversity which was dominated by Mucispirillum and Parabacteroides genera in comparison to mice kept under lower hygiene conditions. In conclusion, we applied taxonomic microbiome analyses to demonstrate a link between gut microbiome diversity and the clinical course of CLL in humans, as well as the development of CLL in mice. Our novel data serve as a basis for further investigations to decipher the pathological and mechanistic role of intestinal microbiota in CLL development.

Respiratory Status in Children and Exposure to Animal Allergens-The Problem of Reverse Causality in Cross-Sectional Studies

BACKGROUND

Some epidemiological studies suggest that early exposure to animal allergens during infancy reduces the risk of bronchial asthma in school-age children. However, the observed associations in some cases may be an effect of the study used (epidemiological observational studies, especially a cross-sectional study) and indicate reverse causality.

AIM

This study aimed to determine the association between exposure to animal allergens and the prevalence of respiratory diseases, including bronchial asthma, considering the potential impact of reverse causality on the observed relationships.

MATERIAL AND METHODS

An analysis of data from a cross-sectional epidemiological study conducted in 2020 involving 3237 primary school students aged 7-15 years in the Silesian Province (Southern Poland) was carried out. The parents of students completed a questionnaire based on The International Study on Asthma and Allergies in Childhood (ISAAC). The relationship between the occurrence of chronic cough, wheezing, and dyspnea in the last 12 months, night waking due to dyspnea, and asthma in the presence of pets was assessed. Exposure to animal allergens was determined by answering the question, "Are there any furry or feathered animals in the home?" with three response options: "yes; they have been in the past; no" (Scenario 1). For the analyses and to reveal a potential reverse causality effect, the last two response categories regarding pet ownership were combined to form a "no" category in Scenario 2, and the first two answers were combined into a "yes" category in Scenario 3. A chi-square test was used to assess the relationship between variables, and a statistical significance level of p < 0.05 was adopted.

RESULTS

Chronic cough affected 9.5% of children, wheezing in the last 12 months-9.2%, night waking due to dyspnea-5.8%, dyspnea in the last 12 months-4.8%, bronchial asthma-9.2%. Analysis considering the category of having or not having pets (yes vs. no) showed that bronchial asthma was statistically significantly more common in children who did not have pets at home (10.9% vs. 7.9%, p = 0.002). A similar situation was observed for wheezing in the past 12 months (10.7% vs. 8.1%; p = 0.01) and nocturnal awakening due to dyspnea (6.8% vs. 5.1%, p = 0.03). No statistically significant differences were observed for the other symptoms. Analysis by time of pet ownership (a. present; b. present but in the past; c. not present) highlighted similar relationships. Asthma (a. 7.7% vs. b. 13.4% vs. c. 7.7%; p = 0.004), wheezing in the past 12 months (a. 8.1% vs. b. 8.9% vs. c. 10.9%, p = 0.03) and night waking (a. 5.0% vs. b. 4.5% vs. c. 7.1%; p = 0.04) were more common in children without pets and those who had owned pets in the past. The highest proportion of children with asthma was in homes where pets were present in the past.

CONCLUSIONS

Analyses indicating a relationship between a higher prevalence of asthma and some respiratory symptoms, and the absence of pets cannot be considered as a casual association. The analysis conducted did not reveal a reverse causality effect. The results of observational epidemiological studies, especially a cross-sectional study, should always be interpreted with caution, considering possible distortions and conclusions drawn.

Unraveling the gut microbiota's role in Rheumatoid arthritis: dietary pathways to modulation and therapeutic potential

Rheumatoid arthritis (RA) is a significant global health issue. Recent research highlights the gut microbiota's critical role in RA's development, noting how dietary factors can alter these microbial communities. This has led to an increased focus on how the gut microbiota (GM) influences RA and the potential for dietary ingredients to offer anti-RA benefits by modifying GM. This review presents a concise examination of the GM associated with RA, identifying specific microbial taxa at various levels that are implicated in the disease. It delves into dietary components known for their anti-RA properties through GM modulation and their mechanisms. Findings from numerous studies, including both animal and human research, show significant differences in the GM composition between individuals with early and established RA. Certain microbes like Tenericutes, Synergistetes, and Proteobacteria have been linked to RA progression, whereas Bacteroidetes and some strains of Lactobacillus are shown to have protective effects against RA. Dietary elements such as fibers, polysaccharides, resistant starch, and peptides have been identified as influential in combating RA. These components work by altering the GM's metabolites and impacting immune cells related to the GM. This review suggests the potential for developing functional foods aimed at treating RA by targeting GM.

Gut microbiome signature and nasal lavage inflammatory markers in young people with asthma

Background

Asthma is a complex disease and a severe global public health problem resulting from interactions between genetic background and environmental exposures. It has been suggested that gut microbiota may be related to asthma development; however, such relationships needs further investigation.

Objective

This study aimed to characterize the gut microbiota as well as the nasal lavage cytokine profile of asthmatic and nonasthmatic individuals.

Methods

Stool and nasal lavage samples were collected from 29 children and adolescents with type 2 asthma and 28 children without asthma in Brazil. Amplicon sequencing of the stool bacterial V4 region of the 16S rRNA gene was performed using Illumina MiSeq. Microbiota analysis was performed by QIIME 2 and PICRUSt2. Type 2 asthma phenotype was characterized by high sputum eosinophil counts and positive skin prick tests for house dust mite, cockroach, and/or cat or dog dander. The nasal immune marker profile was assessed using a customized multiplex panel.

Results

Stool microbiota differed significantly between asthmatic and nonasthmatic participants (P = .001). Bacteroides was more abundant in participants with asthma (P < .05), while Prevotella was more abundant in nonasthmatic individuals (P < .05). In people with asthma, the relative abundance of Bacteroides correlated with IL-4 concentration in nasal lavage samples. Inference of microbiota functional capacity identified differential fatty acid biosynthesis in asthmatic compared to nonasthmatic subjects.

Conclusion

The stool microbiota differed between asthmatic and nonasthmatic young people in Brazil. Asthma was associated with higher Bacteroides levels, which correlated with nasal IL-4 concentration.

Influence of the gut and airway microbiome on asthma development and disease

There are ample data to suggest that early-life dysbiosis of both the gut and/or airway microbiome can predispose a child to develop along a trajectory toward asthma. Although individual studies show clear associations between dysbiosis and asthma development, it is less clear what (collection of) bacterial species is mechanistically responsible for the observed effects. This is partly due to issues related to the asthma diagnosis and the broad spectrum of anatomical sites, sample techniques, and analysis protocols that are used in different studies. Moreover, there is limited attention for potential differences in the genetics of individuals that would affect the outcome of the interaction between the environment and that individual. Despite these challenges, the first bacterial components were identified that are able to affect the transcriptional state of human cells, ergo the immune system. Such molecules could in the future be the basis for intervention studies that are now (necessarily) restricted to a limited number of bacterial species. For this transition, it might be prudent to develop an ex vivo human model of a local mucosal immune system to better and safer explore the impact of such molecules. With this approach, we might move beyond association toward understanding of causality.

Mucosal IgA immune complex induces immunomodulatory responses in allergic airway and intestinal TH2 disease

BACKGROUND

IgA is the most abundant immunoglobulin at the mucosal surface and although its role in regulating mucosal immunity is not fully understood, its presence is associated with protection from developing allergic disease.

OBJECTIVE

We sought to determine the role of IgA immune complexes for therapeutic application to mucosal allergic responses.

METHODS

Trinitrophenol (TNP)-specific IgA immune complexes were applied, using TNP-coupled ovalbumin (OVA), to airway and gut mucosal surfaces in systemically sensitized allergic animals to regulate allergen challenge responses. Animals were assessed for both pathologic and immune-mediated responses in the lung and gut, respectively, using established mouse models.

RESULTS

The mucosal application of IgA immune complexes in the lung and gut with TNP-OVA regulated TH2-driven allergic response in the lung and gut, reducing TH2 cytokines and mucus (lung) as well as diarrhea and temperature loss (gut), but increasing IL-10 and the number of regulatory T cells. The IgA-OVA immune complex did not alter peanut-induced anaphylaxis, indicating antigen specificity. Using OVA-specific DO.11-green fluorescent protein IL-4 reporter mouse-derived TH2-skewed cells in a transfer model demonstrated that mucosal IgA immune complex treatment reduced TH2-cell expansion and increased the number of regulatory T cells. To address a potential mechanism of action, TGF-β and IL-10 were induced in bone marrow-derived dendritic cells when they were exposed to IgA immune complex, suggesting a regulatory phenotype induced in dendritic cells that also led to an altered primary T-cell-mediated response in in vitro OVA-specific assays.

CONCLUSIONS

These studies highlight one possible mechanism of how allergen-specific IgA may provide a regulatory signal to reduce the development of allergic responses in the lung and gut.

Indoor Airborne Microbiome and Endotoxin: Meteorological Events and Occupant Characteristics Are Important Determinants

Airborne bacteria and endotoxin may affect asthma and allergies. However, there is limited understanding of the environmental determinants that influence them. This study investigated the airborne microbiomes in the homes of 1038 participants from five cities in Northern Europe: Aarhus, Bergen, Reykjavik, Tartu, and Uppsala. Airborne dust particles were sampled with electrostatic dust fall collectors (EDCs) from the participants' bedrooms. The dust washed from the EDCs' clothes was used to extract DNA and endotoxin. The DNA extracts were used for quantitative polymerase chain (qPCR) measurement and 16S rRNA gene sequencing, while endotoxin was measured using the kinetic chromogenic limulus amoebocyte lysate (LAL) assay. The results showed that households in Tartu and Aarhus had a higher bacterial load and diversity than those in Bergen and Reykjavik, possibly due to elevated concentrations of outdoor bacterial taxa associated with low precipitation and high wind speeds. Bergen-Tartu had the highest difference (ANOSIM R = 0.203) in β diversity. Multivariate regression models showed that α diversity indices and bacterial and endotoxin loads were positively associated with the occupants' age, number of occupants, cleaning frequency, presence of dogs, and age of the house. Further studies are needed to understand how meteorological factors influence the indoor bacterial community in light of climate change.

The Interplay between Microbiota and Human Complex Traits

Microorganisms have been one of the most influential drivers propelling some of the greatest environmental and evolutionary changes in the landscape and biology of the entire planet [...].

Gut and reproductive tract microbiota: Insights into the pathogenesis of endometriosis (Review)

Endometriosis is characterized by the presence of endometrial-like tissue outside the uterus and is associated with an inflammatory immune response. The gut and reproductive tract microbiota constitute a protective barrier against infection by pathogens and regulate inflammatory and immune functions. This review summarizes microbiota imbalance (i.e., dysbiosis) in endometriosis and discusses how dysbiosis influences disease development. The literature was searched for studies published from inception to March 2022 in the PubMed and Google Scholar databases using a combination of specific terms. An altered gut and reproductive tract microbiome has been reported in numerous conditions, such as inflammatory bowel disease, allergies, autoimmunity, cancer and reproductive disorders (e.g., endometriosis). Furthermore, microbial dysbiosis is a hallmark of endometriosis and is characterized by a decrease in beneficial probiotics and an increase in pathogenic microbes, which leads to a series of estrobolomic and metabolomic changes. Gut or reproductive tract microbiome dysbiosis was reported in mice, nonhuman primates, and females with endometriosis. Animal models of endometriosis demonstrated the effects of the gut microbiome on lesion growth and vice versa. The immune system mediated by the microbiota-gut-reproductive tract axis triggers an inflammatory response that damages reproductive tract tissue, which possibly leads to endometriosis. However, whether the alteration of eubiosis (a balanced microbiota) to dysbiosis is a cause or a result of endometriosis is unclear. In conclusion, this review provides an overview of the relationship between the gut and reproductive tract microbiome and endometriosis, focusing on the mechanisms by which dysbiosis may increase the risk of disease.

Medical Astro-Microbiology: Current Role and Future Challenges

The second and third decades of the twenty-first century are marked by a flourishing of space technology which may soon realise human aspirations of a permanent multiplanetary presence. The prevention, control and management of infection with microbial pathogens is likely to play a key role in how successful human space aspirations will become. This review considers the emerging field of medical astro-microbiology. It examines the current evidence regarding the risk of infection during spaceflight via host susceptibility, alterations to the host's microbiome as well as exposure to other crew members and spacecraft's microbiomes. It also considers the relevance of the hygiene hypothesis in this regard. It then reviews the current evidence related to infection risk associated with microbial adaptability in spaceflight conditions. There is a particular focus on the International Space Station (ISS), as one of the only two  crewed objects in low Earth orbit. It discusses the effects of spaceflight related stressors on viruses and the infection risks associated with latent viral reactivation and increased viral shedding during spaceflight. It then examines the effects of the same stressors on bacteria, particularly in relation to changes in virulence and drug resistance. It also considers our current understanding of fungal adaptability in spaceflight. The global public health and environmental risks associated with a possible re-introduction to Earth of invasive species are also briefly discussed. Finally, this review examines the largely unknown microbiology and infection implications of celestial body habitation with an emphasis placed on Mars. Overall, this review summarises much of our current understanding of medical astro-microbiology and identifies significant knowledge gaps.

Graphical Abstract

Programming Factors of Neonatal Intestinal Dysbiosis as a Cause of Disease

The intestinal microbiota consists of trillions of bacteria, viruses, and fungi that achieve a perfect symbiosis with the host. They perform immunological, metabolic, and endocrine functions in the body. The microbiota is formed intrauterine. Dysbiosis is a microbiome disorder characterized by an imbalance in the composition of the microbiota, as well as changes in their functional and metabolic activities. The causes of dysbiosis include improper nutrition in pregnant women, hormone therapy, the use of drugs, especially antibiotics, and a lack of exposure to the mother's vaginal microbiota during natural birth. Changes in the intestinal microbiota are increasingly being identified in various diseases, starting in the early neonatal period into the adult period. Conclusions: In recent years, it has become more and more obvious that the components of the intestinal microbiota are crucial for the proper development of the immune system, and its disruption leads to disease.

Molecular Accounting and Profiling of Human Respiratory Microbial Communities: Toward Precision Medicine by Targeting the Respiratory Microbiome for Disease Diagnosis and Treatment

The wide diversity of microbiota at the genera and species levels across sites and individuals is related to various causes and the observed differences between individuals. Efforts are underway to further understand and characterize the human-associated microbiota and its microbiome. Using 16S rDNA as a genetic marker for bacterial identification improved the detection and profiling of qualitative and quantitative changes within a bacterial population. In this light, this review provides a comprehensive overview of the basic concepts and clinical applications of the respiratory microbiome, alongside an in-depth explanation of the molecular targets and the potential relationship between the respiratory microbiome and respiratory disease pathogenesis. The paucity of robust evidence supporting the correlation between the respiratory microbiome and disease pathogenesis is currently the main challenge for not considering the microbiome as a novel druggable target for therapeutic intervention. Therefore, further studies are needed, especially prospective studies, to identify other drivers of microbiome diversity and to better understand the changes in the lung microbiome along with the potential association with disease and medications. Thus, finding a therapeutic target and unfolding its clinical significance would be crucial.

Rural Embodiment and Community Health: an Anthropological Case Study on Biocultural Determinants of Tropical Disease Infection and Immune System Development in the USA

Purpose of Review

Biocultural methods are critically important for identifying environmental and socioeconomic factors linked with tropical disease risk and outcomes. For example, embodiment theory refers to the process by which lived experiences impact individual biology. Increased exposure to pathogens, chronic psychosocial stress, and unequal resource access are all outcomes linked with discrimination and poverty. Through lived experiences, race and socioeconomic inequality can literally become embodied-get under the skin and affect physiology-impacting immune responses and contributing to lifelong health disparities. Yet, few studies have investigated tropical disease patterns and associated immune function using embodiment theory to understand lasting physiological impacts associated with living in a high-pathogen environment.

Recent Findings

Here, we use preliminary data drawn from the Rural Embodiment and Community Health (REACH) study to assess whether pathogen exposure and immune stimulation within a sample of children from the Mississippi Delta are associated with household income. We also test whether immune marker levels-assessed with enzyme-linked immunosorbent assays using dried blood spot samples-vary between the REACH sample and a similarly aged nationally representative NHANES sample. Immune marker levels did not differ significantly between REACH participants living below vs. above the federal poverty line, yet immunoglobulin E levels-a marker of macroparasite infection-were higher among REACH study participants compared to the NHANES sample.

Summary

These results may suggest community-level pathogenic exposures (i.e., parasitic infections) are embodied by REACH participants with implications for long-term immune function, potentially resulting in immune aspects that differ from nationally representative samples.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40475-023-00282-z.

Short Chain Fatty Acid Metabolism in Relation to Gut Microbiota and Genetic Variability

It is widely accepted that the gut microbiota plays a significant role in modulating inflammatory and immune responses of their host. In recent years, the host-microbiota interface has gained relevance in understanding the development of many non-communicable chronic conditions, including cardiovascular disease, cancer, autoimmunity and neurodegeneration. Importantly, dietary fibre (DF) and associated compounds digested by the microbiota and their resulting metabolites, especially short-chain fatty acids (SCFA), were significantly associated with health beneficial effects, such as via proposed anti-inflammatory mechanisms. However, SCFA metabolic pathways are not fully understood. Major steps include production of SCFA by microbiota, uptake in the colonic epithelium, first-pass effects at the liver, followed by biodistribution and metabolism at the host's cellular level. As dietary patterns do not affect all individuals equally, the host genetic makeup may play a role in the metabolic fate of these metabolites, in addition to other factors that might influence the microbiota, such as age, birth through caesarean, medication intake, alcohol and tobacco consumption, pathogen exposure and physical activity. In this article, we review the metabolic pathways of DF, from intake to the intracellular metabolism of fibre-derived products, and identify possible sources of inter-individual variability related to genetic variation. Such variability may be indicative of the phenotypic flexibility in response to diet, and may be predictive of long-term adaptations to dietary factors, including maladaptation and tissue damage, which may develop into disease in individuals with specific predispositions, thus allowing for a better prediction of potential health effects following personalized intervention with DF.

Relationship between maternal-infant gut microbiota and infant food allergy

The gut microbiota plays a crucial role in food allergies. We sought to identify characteristics of the maternal gut microbiota in the third trimester and the infant gut microbiota in early life and the association of these microbiotas with infant food allergy. A total of 68 healthy pregnant women and their full-term newborns were selected from a cohort of 202 mother-infant pairs; among them, 24 infants had been diagnosed with food allergy within 1 year of age, whereas 44 infants were healthy without allergic symptoms. We collected 65 maternal fecal samples before delivery and 253 infant fecal samples at five time points following birth. Fecal samples were microbiologically analyzed using 16S rRNA gene sequencing. Holdemania abundance in the maternal gut microbiota in the third trimester was significantly higher in the non-allergy group than in the food allergy group (P = 0.036). In the infant gut microbiota, Holdemania was only found in meconium samples; its abundance did not differ significantly between the two groups. The change in the abundance of Actinobacteria over time differed between the non-allergy and food allergy groups (FA, P = 0.013; NA, P = 9.8 × 10-5), and the change in the abundance of Firmicutes over time differed significantly in the non-allergy group (P = 0.023). The abundances of genera Anaerotruncus, Roseburia, Ruminococcus, and Erysipelotricaceae were significantly different between the non-allergy and food allergy groups at different time points. Our results showed that maternal carriage of Holdemania during the third trimester strongly predicted the absence of food allergies in infants; there was no correlation between the presence of food allergies and the abundance of Holdemania in the infant gut microbiota. More dynamic fluctuations in phyla Actinobacteria and Firmicutes early in life protect against food allergy. Thus, the enrichment of the infant gut microbiota early in life with short-chain fatty acid-producing bacteria may be beneficial in preventing the development of food allergies in infants.

Fusobacterium nucleatum infection-induced neurodegeneration and abnormal gut microbiota composition in Alzheimer’s disease-like rats

Objective

To explore whether Fusobacterium nucleatum could lead to behavioral and pathological changes in Alzheimer’s disease (AD)-like model rat and whether they could affect the gut microbiota.

Methods

The cognitive ability and alveolar bone loss of Sprague-Dawley (SD) rats were tested by Morris water maze and Micro-CT, respectively. HE staining and immunohistochemistry were used to analyze the pathological changes and Aβ1–42 in brains. Western blot was applied to detect the expression of p-Tau 181 in the brain. Limulus amebocyte lysate assay and PCR were performed to determine serum LPS level and whether F. nucleatum accessed the brain, respectively. The gut microbiota was analyzed by the 16S rRNA gene sequence.

Results

Oral infection with F. nucleatum could induce increased alveolar bone loss and learning impairment in AD-like rats. Additionally, F. nucleatum exposure increased the Aβ1–42 expression by about one-fourth (P < 0.05), p-Tau181 by about one-third (P < 0.05), and serum LPS (P < 0.05) in AD-like rats. Moreover, F. nucleatum could change the gut microflora composition in AD-like rats, accompanied by a significant increase in the abundance of Streptococcus and Prevotella.

Conclusion

Oral infection with F. nucleatum could contribute to abnormalities in cognitive ability and pathological change in the brain of AD-like rats, which may be related to abnormal gut microbiota composition.

Bioaerosol and microbial exposures from residential evaporative coolers and their potential health outcomes: A review

Evaporative cooling is an energy efficient form of air conditioning in dry climates that functions by pulling hot, dry outdoor air across a wet evaporative pad. While evaporative coolers can help save energy, they also have the potential to influence human health. Studies have shown residential evaporative coolers may pull outdoor air pollutants into the home or contribute to elevated levels of indoor bioaerosols that may be harmful to health. There is also evidence that evaporative coolers can enable a diverse microbial environment that may confer early-life immunological protection against the development of allergies and asthma or exacerbate these same hypersensitivities. This review summarizes the current knowledge of bioaerosol and microbiological studies associated with evaporative coolers, focusing on harmful and potentially helpful outcomes from their use. We evaluate the effects of evaporative coolers on indoor bacterial endotoxins, fungal β-(1 → 3)-D-glucans, dust mite antigens, residential microbial communities, and Legionella pneumophila. To our knowledge, this is the first review to summarize and evaluate studies on the influence that evaporative coolers have on the bioaerosol and microbiological profile of homes. This brings to light a gap in the literature on evaporative coolers, which is the lack of data on health effects associated with their use.

Physicians' Understanding of the Role of the Microbiome in Allergies and Asthma: A Questionnaire-Based Study in Saudi Arabia

Purpose

Allergies and asthma are two noncommunicable illnesses of increasing public health concern in Saudi Arabia. Nevertheless, little is known about knowledge of the microbiome and its relationship to asthma and allergy risks among healthcare professionals, such as pediatricians and family medicine practitioners, who are often involved in the care of patients suffering from these illnesses. Therefore, this study aimed to examine knowledge about microbiome science in these healthcare workers in the eastern region of the kingdom, where allergies and asthma are highly prevalent.

Patients and Methods

The study survey consisted of 37 online questions in three topical domains, including microbiome science, dysbiosis, and probiotics, and was distributed to 203 participants in various demographic groups.

Results

The survey analysis revealed that the mean knowledge score was 67.6%. The component scores were highest for the microbiome (75.6%) and lowest for dysbiosis (52.6%). Only 17.7% of the healthcare workers were prescribing probiotic food or drinks for most of their patients with allergies and/or asthma; and 37.8% of the healthcare workers were unaware of the reasons for prescribing pro-/prebiotics. Regression analysis revealed that older age (>45 years old), probiotic prescription experience, and positive beliefs about the importance of nutritional advice were independent predictors of higher microbiome knowledge.

Conclusion

The analysis not only revealed existing gaps in microbiome knowledge among the participants, including those related to the role of the microbiome in allergy and asthma development but also identified predictors of higher microbiome knowledge. These observations provide an impetus for the rational design of continuing medical education curriculum and training to update healthcare professionals with emerging clinical application of microbiome knowledge for the management of microbiome-related illnesses.

A Two-Time Point Analysis of Gut Microbiota in the General Population of Buenos Aires and Its Variation Due to Preventive and Compulsory Social Isolation During the COVID-19 Pandemic

The COVID-19 pandemic poses a great challenge to global public health. The extraordinary daily use of household disinfectants and cleaning products, social distancing and the loss of everyday situations that allow contact between individuals, have a direct impact on the transfer of microorganisms within the population. Together, these changes, in addition to those that occur in eating habits, can affect the composition and diversity of the gut microbiota. A two-time point analysis of the fecal microbiota of 23 Metropolitan Buenos Aires (BA) inhabitants was carried out, to compare pre-pandemic data and its variation during preventive and compulsory social isolation (PCSI) in 2020. To this end, 23 healthy subjects, who were previously studied by our group in 2016, were recruited for a second time during the COVID-19 pandemic, and stool samples were collected from each subject at each time point (n = 46). The hypervariable region V3-V4 of the 16S rRNA gene was high-throughput sequenced. We found significant differences in the estimated number of observed features (p < 0.001), Shannon entropy index (p = 0.026) and in Faith phylogenetic diversity (p < 0.001) between pre-pandemic group (PPG) vs. pandemic group (PG), being significantly lower in the PG. Although no strong change was observed in the core microbiota between the groups in this study, a significant decrease was observed during PCSI in the phylum Verrucomicrobia, which contributes to intestinal health and glucose homeostasis. Microbial community structure (beta diversity) was also compared between PPG and PG. The differences observed in the microbiota structure by unweighted UniFrac PCoA could be explained by six differential abundant genera that were absent during PCSI. Furthermore, putative functional genes prediction using PICRUSt infers a smaller predicted prevalence of genes in the intestinal tryptophan, glycine-betaine, taurine, benzoate degradation, as well as in the synthesis of vitamin B12 during PCSI. This data supports the hypothesis that the microbiome of the inhabitants of BA changed in the context of isolation during PCSI. Therefore, these results could increase the knowledge necessary to propose strategic nutraceutical, functional food, probiotics or similar interventions that contribute to improving public health in the post-pandemic era.

Food allergy and hypersensitivity reactions in children and adults-A review

Adverse reactions after food intake are commonly reported and a cause of concern and anxiety that can lead to a very strict diet. The severity of the reaction can vary depending on the type of food and mechanism, and it is not always easy to disentangle different hypersensitivity diagnoses, which sometimes can exist simultaneously. After a carefully taken medical history, hypersensitivity to food can often be ruled out or suspected. The most common type of allergic reaction is immunoglobulin E (IgE)-mediated food allergy (prevalence 5-10%). Symptoms vary from mild itching, stomach pain, and rash to severe anaphylaxis. The definition of IgE-mediated food allergy is allergic symptoms combined with specific IgE-antibodies, and therefore only IgE-antibodies to suspected allergens should be analyzed. Nowadays, methods of molecular allergology can help with the diagnostic process. The most common allergens are milk and egg in infants, peanut and tree nuts in children, and fish and shellfish in adults. In young children, milk/egg allergy has a good chance to remit, making it important to follow up and reintroduce the food when possible. Other diseases triggered by food are non-IgE-mediated food allergy, for example, eosinophilic esophagitis, celiac disease, food protein-induced enterocolitis syndrome, and hypersensitivity to milk and biogenic amines. Some of the food hypersensitivities dominate in childhood, others are more common in adults. Interesting studies are ongoing regarding the possibilities of treating food hypersensitivity, such as through oral immunotherapy. The purpose of this review was to provide an overview of the most common types of food hypersensitivity reactions.

Helicobacter pylori infection: How does age influence the inflammatory pattern?

The inflammatory pattern during Helicobacter pylori (H. pylori) infection is changeable and complex. During childhood, it is possible to observe a predominantly regulatory response, evidenced by high concentrations of key cytokines for the maintenance of Treg responses such as TGF-β1 and IL-10, in addition to high expression of the transcription factor FOXP3. On the other hand, there is a predominance of cytokines associated with the Th1 and Th17 responses among H. pylori-positive adults. In the last few years, the participation of the Th17 response in the gastric inflammation against H. pylori infection has been highlighted due to the high levels of TGF-β1 and IL-17 found in this infectious scenario, and growing evidence has supported a close relationship between this immune response profile and unfavorable outcomes related to the infection. Moreover, this cytokine profile might play a pivotal role in the effectiveness of anti-H. pylori vaccines. It is evident that age is one of the main factors influencing the gastric inflammatory pattern during the infection with H. pylori, and understanding the immune response against the bacterium can assist in the development of alternative prophylactic and therapeutic strategies against the infection as well as in the comprehension of the pathogenesis of the outcomes related to that microorganism.

Evaluating Knowledge of Human Microbiota among University Students in Jordan, an Online Cross-Sectional Survey

Human microbiota have a significant impact on the health of individuals, and reciprocally, lifestyle choices of individuals have an important effect on the diversity and composition of microbiota. Studies assessing microbiota knowledge among the public are lacking, although it is hypothesized that this knowledge can motivate healthier behavior. Hence, this study aimed to measure microbiota knowledge among university students, and the effect of this knowledge on behavioral beliefs. A descriptive cross-sectional study was conducted among students from various fields of study enrolled at the University of Jordan, using an online questionnaire. The questionnaire consisted of 3 parts: demographics, general knowledge of microbiota, and behavioral beliefs related to microbiota. Four hundred and two responses were collected from verified university students. Participants were divided into two groups depending on whether they took a formal microbiology course (45 h) or not. Results from those two groups were compared using appropriate statistical methods. Results showed that most participants, even those who did not take a formal microbiology course, displayed good knowledge of what microbiota is and how they can be influenced by personal and environmental factors. Participants who took a microbiology course had significantly higher microbiota knowledge scores and were more aware of the effect of antibiotics on microbiota. Participants' behavioral beliefs regarding their antibiotic use, but not their diet and lifestyle choices, were affected by their knowledge of microbiota. The study indicates that disseminating knowledge regarding microbiota and microbiology in general, can improve behaviors related to antibiotic use.

Microbiome Research and Multi-Omics Integration for Personalized Medicine in Asthma

Asthma is a multifactorial inflammatory disorder of the respiratory system characterized by high diversity in clinical manifestations, underlying pathological mechanisms and response to treatment. It is generally established that human microbiota plays an essential role in shaping a healthy immune response, while its perturbation can cause chronic inflammation related to a wide range of diseases, including asthma. Systems biology approaches encompassing microbiome analysis can offer valuable platforms towards a global understanding of asthma complexity and improving patients' classification, status monitoring and therapeutic choices. In the present review, we summarize recent studies exploring the contribution of microbiota dysbiosis to asthma pathogenesis and heterogeneity in the context of asthma phenotypes-endotypes and administered medication. We subsequently focus on emerging efforts to gain deeper insights into microbiota-host interactions driving asthma complexity by integrating microbiome and host multi-omics data. One of the most prominent achievements of these research efforts is the association of refractory neutrophilic asthma with certain microbial signatures, including predominant pathogenic bacterial taxa (such as Proteobacteria phyla, Gammaproteobacteria class, especially species from Haemophilus and Moraxella genera). Overall, despite existing challenges, large-scale multi-omics endeavors may provide promising biomarkers and therapeutic targets for future development of novel microbe-based personalized strategies for diagnosis, prevention and/or treatment of uncontrollable asthma.

Atopic diseases and airway-related symptoms in Bavarian children before starting primary school: Time trend analyses

BACKGROUND

After decades of rising prevalence of atopic and airway-related diseases, studies showed stagnating prevalence in western industrialised countries. Objective of this study is to analyse the time trend of prevalence of atopic diseases and airway-related symptoms among Bavarian children before starting primary school.

MATERIALS AND METHODS

Five cross-sectional studies from 2004/2005, 2006/2007, 2012/2013, 2014/2015 and 2016/2017 took place in urban and rural regions in Bavaria, Germany. Using standardized parent questionnaires children's atopic diseases and airway-related symptoms were surveyed. Logistic regression analysis (Bonferroni correction: adjusted significance level 0.005) was performed to analyse prevalence of symptoms and diseases from 2004 to 2017 for time trends.

RESULTS

The surveys included 27384 Bavarian children aged 5-6 years (52.6% male). In all children the calculated 12-month prevalence of symptoms '≥four episodes of wheeze' (p-value = .0880) and 'rhinoconjunctivitis' (p-value = .3994) reported by parents stagnated, whereas 'wheeze' (p-value<.0001; OR = 0.97; CI = [0.96-0.98]) and 'rhinitis' (p-value = .0007; OR = 0.98; CI = [0.97-0.99]) decreased. In all children the calculated lifetime prevalence of physician-diagnosed 'asthma' (p-value = .5337), and 'hay fever' (p-value = .8206) stagnated, whereas of 'bronchitis' (p-value<.0001; OR = 0.98; CI = [0.98-0.99]) decreased over time. The calculated lifetime prevalence of physician-diagnosed 'atopic eczema' (p-value = .0002; OR = 0.98; CI = [0.97-0.99]) decreased in all children, whereas the calculated 12-month prevalence of the symptom 'itchy rash' increased (p-value = .0033; OR = 1.07; CI = [1.05-1.08]) over time.

CONCLUSIONS

Several calculated prevalence of children's atopic diseases and airway-related symptoms reported by parents stagnated in a subgroup of Bavarian children before starting primary school between 2004 and 2017. The time trend of prevalence in 'wheeze', 'rhinitis' and 'bronchitis' decreased. Prevalence of 'atopic eczema' decreased over time, whereas 'itchy rash' increased.

Baby's skin bacteria: first impressions are long-lasting

Early life is a dynamic period for skin microbial colonization and immune development. We postulate that microbial exposures in this period durably alter the skin immune trajectory and later disease susceptibility. Bacteria contribute to infant skin immune imprinting via interactions with microbes as well as with cutaneous epithelial and immune cells. Excellent research is underway at the skin microbiome-immune interface, both in deciphering basic mechanisms and implementing their therapeutic applications. As emphasized herein, focusing on the unique opportunities and challenges presented by microbial immune modulation in early life will be important. In our view, only through dedicated study of skin-microbe crosstalk in this developmental window can we elucidate the molecular underpinnings of pivotal events that contribute to sustained host-microbe symbiosis.

Substantiation of the composition of a semi-solid dosage form with a probiotic component for use in dermatology

One of the important issues in the pharmaceutical development of a semisolid preparation for dermal use is the scientific and experimental justification for choosing the base-carrier of active substances. The aim of this study was to experimentally substantiate the choice of rational combination of excipients in the development of a semisolid dosage form with a probiotic component for use in dermatology. Materials and methods. Hydrophilic gelling agents were used as excipients in the study: Sepiplus 400, Aristoflex AVC, Carbopol 934, hydroxyethylcellulose HEC, sodium alginate. Physical and chemical, pharmaco-technological and microbiological methods were used to select the optimal basis. Colloidal stability was determined using a laboratory centrifuge at a speed of 6000 rpm for 5 min, an electronic thermometer and a water bath laboratory. Thermostability was determined in the thermostat at (40±2) °C for 24 hours. Investigation of the rheological properties of the samples was performed using a Rheolab QC (Anton Paar, Austria) rheoviscometer using a system of coaxial cylinders C-CC27/SS. The kinetics of water absorption of the samples were studied by dialysis through a semipermeable Cuprophan membrane, Type 150 pm at a temperature of (34±2) °C. The number of viable lactobacilli cells was determined by surface seeding on Petri dishes with dense MRS medium. Research results. The results of the study of the number of viable lactobacilli cells showed that the lowest number of viable cells was in sample based on HEC. Tests for thermostability and colloidal stability showed that for sample No. 5 based on sodium alginate, stratification was observed in the experiment, which indicates its instability. These samples were excluded. Samples on Sepiplus 400 and Aristoflex AVC on a set of rheological features have advantages both consumer and technological; and sample on t Aristoflex AVC has the best indicators of osmotic activity and the viability of cells in the dynamics for this study. Conclusions. As a result of physical and chemical (organoleptic, colloidal and thermostability), pharmaco-technological (osmotic and structural and mechanical properties) and microbiological studies (number of viable lactobacilli cells) studies it was found that further work should be carried out with a sample based on gelling agent Aristoflex AVC, which has the most optimal performance in this development for a semisolid dosage form with a probiotic component for use in dermatology

The Role of the Environment in Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a chronic immune-mediated disease clinicopathologically characterized by esophageal dysfunction. EoE is characterized by eosinophilic histologic inflammation indistinguishable from other atopic diseases such as asthma, eczema, or allergic rhinitis, which often co-occur in patients with EoE. This suggest a possible shared pathophysiology and triggers in the development of EoE with other atopic conditions. Although the evidence of EoE being linked to exposure to allergenic foods is strong, the connection between EoE and aeroallergens is less understood. In this review, we will discuss clinical, epidemiological, and animal studies that investigate how environmental allergens influence the clinical manifestations of EoE and its seasonality. It is also known that the developing immune system is significantly shaped by early-life exposures, pollution, climate change, and those factors that are known to influence development of asthma. We therefore also describe the evidence for and the gaps in our knowledge of the role of early-life exposures, pollution, and climate change in the development of EoE.

Higher educational level in patients with eosinophilic esophagitis: a comparative analysis

BACKGROUND

Eosinophilic esophagitis is a chronic inflammatory gastrointestinal disease with a high prevalence in younger, atopic males. In our clinical practice, we observed a striking preponderance of patients having a high educational background. The purposes of this study were first to assess the level of education of eosinophilic esophagitis patients and second to compare the findings to patients with inflammatory bowel disease, another chronic immune-mediated condition of the gastrointestinal tract, and with the Swiss general population.

METHODS

Using a questionnaire, we assessed the educational level of adult patients who have attended Swiss Eosinophilic Esophagitis Clinics in the past. In addition, the educational level of the parents was assessed as well. We calculated the proportions of patients and parents who have obtained a higher educational level. Data from the Swiss Inflammatory Bowel Disease Cohort Study and from the Swiss general population served as confirmation and as comparison, respectively.

RESULTS

A total of 277 successfully contacted patients (response rate 69.1%; mean age 51.1 years, 73% male) participated. A significantly higher proportion of surveyed eosinophilic esophagitis patients had a high International Standard Classification of Education level (66.8%, P < 0.001) compared with inflammatory bowel disease patients (n = 2534; 34.2%, P < 0.001) and to the Swiss general population (n = 6,066,907; 30.5% P < 0.001).

CONCLUSION

Our analysis confirms the clinical observation that eosinophilic esophagitis patients have a significantly higher educational level compared with the general population and to patients with other chronic inflammatory diseases of the gastrointestinal tract. As a limitation, this impressive finding remains on a purely descriptive level.

Skin Microbiome-The Next Frontier for Probiotic Intervention

The skin is the largest organ in the human body, and it orchestrates many functions that are fundamentally important for our survival. Although the skin might appear to present a relatively inhospitable or even hostile environment, a multitude of commensals and also some potentially pathogenic microorganisms have successfully adapted to survive and/or thrive within the diverse ecological niches created by the skin's topographical architecture. Dysbiosis within these microbial populations can result in the emergence and pathological progression of skin diseases. Unsurprisingly, this has led to a new focus of research both for the medical dermatology and cosmetic industries that is concerned with modulation of the skin microbiome to help address common microbially mediated or modulated conditions such as acne, body odour, and atopic dermatitis. This review presents an overview of our current understanding of the complex relationship of the skin with its microbiome and then introduces the concept of probiotic intervention for the management of microbial dysbiosis within the skin ecosystem.

Patterns of allergic sensitization and factors associated with emergence of sensitization in the rural tropics early in the life course: findings of an Ecuadorian birth cohort

Introduction

There are limited data on emergence of allergic sensitization (or atopy) during childhood in tropical regions.

Methods

We followed a birth cohort of 2404 newborns to 8 years in tropical Ecuador and collected: risk factor data by maternal questionnaires periodically from birth; atopy was measured by skin prick test reactivity (SPT) to aeroallergens in parents, and aeroallergens and food allergens in children at 2, 3, 5, and 8 years; and stool samples for soil-transmitted helminths (STH) from children periodically to 8 years and from parents and household members at the time of recruitment of cohort children. Data on risk factors were measured either at birth or repeatedly (time-varying) from birth to 8 years. Longitudinal repeated-measures analyses were done using generalized estimating equations to estimate an the age-dependent risk of positive SPT (SPT+) to any allergen or mite during early childhood to school age.

Results

SPT+ to any allergen was present in 29.0% of fathers and 24.8% of mothers, and in cohort children increased with age, initially to mite but later to cockroach, reaching 14.8% to any allergen (10.7% mite and 5.3% cockroach) at 8 years. Maternal SPT+, particularly presence of polysensitization (OR 2.04, 95% CI 1.49-2.77) significantly increased the risk of SPT+ during childhood, while household overcrowding at birth decreased the risk (OR 0.84, 95% CI 0.72-0.98). For mite sensitization, maternal polysensitization increased (OR 2.14, 95% CI 1.40-3.27) but rural residence (OR 0.69, 95% CI 0.50-0.94) and birth order (3^rd -4^th vs. 1^st - 2^nd: OR 0.71, 95% CI 0.52-0.98) decreased the risk. Time-varying exposures to agricultural activities (OR 0.77, 95% CI 0.60-0.98) and STH parasites (OR 0.70, 95% CI 0.64-0.91) during childhood decreased while anthelmintics increased the childhood risk (OR 1.47, 95% CI 1.05-2.05) of mite sensitization.

Conclusion

Our data showed the emergence of allergic sensitization, primarily to mite and cockroach allergens, during childhood in tropical Ecuador. A role for both antenatal and postnatal factors acting as potential determinants of SPT+ emergence was observed.

Parasite-based interventions in systemic lupus erythematosus (SLE): A systematic review

BACKGROUND

The hygiene hypothesis proposed in 1989 expresses that allergic and infectious diseases are inversely related. Accordingly, it has been demonstrated that infection with some microorganisms such as parasites and helminths can provide a potential immunity and prevent the onset of some life-threatening autoimmune diseases like systemic lupus erythematosus (SLE). Therefore, in this comprehensive study, we systematically reviewed and discussed the use of live parasites or parasitic products in the treatment of mouse models of SLE.

METHODS

The present systematic review was performed using the following search terms: ("systemic lupus erythematosus" OR "SLE" OR "lupus") AND ("parasite" OR "protozoa" OR "helminths" OR "worms" OR "helminth" OR "worm") in PubMed, Scopus, and Web of Science online databases. We included studies reporting the effect of any intervention using parasites or parasitic-based products on animal models of SLE, which were published until January 20th, 2021 without any language or date restrictions. For each included study, we extracted the authors' names, publication year, type of animal, number of groups, types of intervention, sample size, changes in immunologic cells, auto-Abs, cytokines, and blood cells count, urine analysis, histological analysis of kidney/spleen/liver, outcome and survival. (PROSPERO CRD42020160460).

RESULTS

A total of 17 eligible articles were included in this systematic review. Sixteen out of the 17 studies reported immunomodulating changes in immunologic cells, cytokines, and/or auto-Abs in mouse models of SLE after using parasitic interventions compared to not-infected or control groups. Moreover, 14 studies reported decreased level of proteinuria and/or favorable kidney, liver, or spleen histological changes.

CONCLUSION

In conclusion, we have demonstrated that parasites like Hymenolepis microstoma, TPC and ES-62 from Acanthocheilonema viteae, Plasmodium chabaudi, Schistosoma mansoni, and Toxoplasma gondii have favorable immunomodulating effects on SLE outcomes in lupus-prone mice.

Associations between Environmental dust composition and Atopic Dermatitis in urban and rural settings

BACKGROUND

Environmental exposures are involved in the pathogenesis of the allergic phenotype and in determining which individual triggers a person becomes sensitized to. Atopic dermatitis (AD) may modulate these effects through increased penetration through the skin modifying the immune system and AD may be triggered or intensified by environmental exposures. These exposures and immune-modulating factors may differ in urban and rural environments.

OBJECTIVES

To compare house dust composition in urban and rural settings and correlate them with AD outcomes.

METHODS

Dust samples were collected from the beds of 156 children aged 6 months to 3 years. 42% of participants had atopic dermatitis. Samples were analyzed for bacterial endotoxin, fungal (β-1,3-glucan) levels, and house dust mite, cockroach, dog, cat, mouse, and peanut allergen. Exposures were compared in urban and rural environments and in participants with and without AD.

RESULTS

Endotoxin but not fungal β-glucan exposure is higher in the environment of healthy controls than children with AD in both urban and rural settings. House dust mite allergen exposure is high in urban and rural settings with Dermatophagoides detected in 100% of samples. Cat and dog allergen exposure mirrors pet ownership patterns which differ slightly between groups and environments. Mouse allergen exposure is higher in urban homes.

CONCLUSION

Environmental endotoxin may be protective against AD in both urban and rural settings. There are marked differences in allergen exposure in urban and rural settings, but these are unlikely to be important protective or risk factors.

Maternal microbiome in preeclampsia pathophysiology and implications on offspring health

Preeclampsia is a devastating hypertensive pregnancy disorder that currently affects 2%–8% of pregnancies worldwide. It is associated with maternal and fetal mortality and morbidity and adverse health outcomes both in mom and offspring beyond pregnancy. The pathophysiology is not completely understood, and there are no approved therapies to specifically treat for the disease, with only few therapies approved to manage symptoms. Recent advances suggest that aberrations in the composition of the microbiome may play a role in the pathogenesis of various diseases including preeclampsia. The maternal and uteroplacental environments greatly influence the long‐term health outcomes of the offspring through developmental programming mechanisms. The current review summarizes recent developments on the role of the microbiome in adverse pregnancy outcomes with a focus on preeclampsia. It also discusses the potential role of the maternal microbiome in fetal programming; explores gut‐targeted therapeutics advancement and their implications in the treatment of preeclampsia.

Effects of grape products on inflammation and oxidative stress: A systematic review and meta-analysis of randomized controlled trials

This systematic review and meta-analysis of randomized controlled trials (RCTs) were conducted to determine the effects of grapes and grape products on inflammation and oxidative stress among adults. PubMed, Scopus, ISI Web of Science, and Cochrane Library databases were searched up to July 2020 to identify RCTs investigating the effects of grape and grape products on inflammatory and oxidative stress markers. Weighted mean differences (WMD) were pooled using a random-effects model. Of the 8,962 identified studies, 24 RCTs (27 arms) were included in the statistical analysis. Grape products significantly reduced serum C-reactive protein (CRP) levels (WMD: -0.35 mg/L; 95% CI: -0.62, -0.09, p = .008), but they had no significant effect on serum tumor necrosis factor-alpha (TNF-α) (WMD = -1.08 pg/ml; 95% CI: -2.29, 0.11, p = .07), interleukin-6 (IL-6) (WMD = 0.13 pg/ml; 95% CI: -0.35, 0.60, p = .60), total antioxidant capacity (TAC) (WMD = 0.15; 95% CI: -0.35, 0.65, p = .54), or malondialdehyde (MDA) (WMD = 0.14; 95% CI: -0.64, 0.92, p = .72). The analysis indicated possible decreasing effects of grapes and grape products on CRP, but they might not be able to change IL-6, TNF-α, TAC, and MDA concentrations. Nonetheless, further studies are warranted before definitive conclusions may be reached.

The effects of antibiotic exposure on asthma in children with atopic dermatitis

Early-life antibiotic use is associated with allergic diseases. The risk factors for the progression from atopic dermatitis (AD) to asthma or allergic rhinitis are still unknown. We aimed to investigate the association between exposure to different antibiotics and the risk of new-onset asthma in children with AD. By using the Longitudinal Health Insurance Database 2005, we selected AD patients less than 6 years old identified by ICD-9-CM code 691.8. The case group was defined as those having new-onset asthma, and the control group was defined as those without an asthma history. Information on antibiotic exposure in the 5 years prior to the index date was collected from drug prescription records. We estimated the adjusted odds ratio by using conditional logistic regression, adjusted for age, sex, index year, other potential risk factors and antibiotics. Antibiotic exposure was associated with the development of asthma in patients with AD (aOR = 3.68, 95% CI 2.13–6.36), particularly for patients less than 5 years old (aOR = 4.14, 95% CI 2.24–7.64) (p for trend < 0.001), even though lower cumulative antibiotic defined daily doses (DDDs) were associated with new-onset asthma occurrence. Antibiotic exposure, especially macrolide exposure, is associated with an increased risk of asthma in patients with AD.

The evidence for interventions in early childhood allergy prevention - towards a living systematic review: protocol

Background: Research in early childhood allergy prevention (ECAP) is flourishing and new intervention strategies have proven to be promising. Due to the dynamic nature of ECAP, gaps between what is known and how guidelines inform practice are likely. A living systematic review (LSR) can narrow this gap by incorporating new evidence as it becomes available. No efficacy comparisons across various ECAP interventions for similar outcomes have been carried out. Networks of randomised clinical trials can be evaluated in the context of a network meta-analysis (NMA). We aim to establish a LSR on the efficacy and safety of any intervention investigated in randomised controlled trials (RCT) to prevent the occurrence of allergic sensitisation (AS), symptoms or diagnoses of allergic diseases in infancy and early childhood (0-3 years). Methods: A baseline SR will synthesise the evidence from existing SRs of RCTs as well as RCTs not yet considered in these. After completion of the baseline SR we propose to conduct a LSR. Using this methodology, we aim to undertake constant evidence surveillance, three-monthly search updates, and review updates every three months, should new evidence emerge. Conclusions: The ECAP evidence landscape has undergone dramatic transformations and this process is likely to continue. As a response to this, a LSR offers the potential to allow more timely synthesis of new evidence as it emerges. Long gaps between updates of SRs makes it harder for guidelines and recommendations to be up to date. Users of information, such as parents, may be confused if they encounter new evidence that is not part of a trusted guideline. A LSR approach allows us to continuously search the literature and update the evidence-base of existing ECAP interventions resulting in a decreased timespan from evidence accrual to informing clinical practice.

The evidence for interventions in early childhood allergy prevention - towards a living systematic review: protocol

Background: Research in early childhood allergy prevention (ECAP) is flourishing and new intervention strategies have proven to be promising. Due to the dynamic nature of ECAP, gaps between what is known and how guidelines inform practice are likely. A living systematic review (LSR) can narrow this gap by incorporating new evidence as it becomes available. No efficacy comparisons across various ECAP interventions for similar outcomes have been carried out. Networks of randomised clinical trials can be evaluated in the context of a network meta-analysis (NMA). We aim to establish a LSR on the efficacy and safety of any intervention investigated in randomised controlled trials (RCT) to prevent the occurrence of allergic sensitisation (AS), symptoms or diagnoses of allergic diseases in infancy and early childhood (0-3 years). Methods: A baseline SR will synthesise the evidence from existing SRs of RCTs as well as RCTs not yet considered in these. After completion of the baseline SR we propose to conduct a LSR. Using this methodology, we aim to undertake constant evidence surveillance, three-monthly search updates, and review updates every three months, should new evidence emerge. Conclusions: The ECAP evidence landscape has undergone dramatic transformations and this process is likely to continue. As a response to this, a LSR offers the potential to allow more timely synthesis of new evidence as it emerges. Long gaps between updates of SRs makes it harder for guidelines and recommendations to be up to date. Users of information, such as parents, may be confused if they encounter new evidence that is not part of a trusted guideline. A LSR approach allows us to continuously search the literature and update the evidence-base of existing ECAP interventions resulting in a decreased timespan from evidence accrual to informing clinical practice.

The Hygiene Hypothesis - Learning From but Not Living in the Past

Postulated by Strachan more than 30 years ago, the Hygiene Hypothesis has undergone many revisions and adaptations. This review journeys back to the beginnings of the Hygiene Hypothesis and describes the most important landmarks in its development considering the many aspects that have refined and generalized the Hygiene Hypothesis over time. From an epidemiological perspective, the Hygiene Hypothesis advanced to a comprehensive concept expanding beyond the initial focus on allergies. The Hygiene Hypothesis comprise immunological, microbiological and evolutionary aspects. Thus, the original postulate developed into a holistic model that explains the impact of post-modern life-style on humans, who initially evolved in close proximity to a more natural environment. Focusing on diet and the microbiome as the most prominent exogenous influences we describe these discrepancies and the resulting health outcomes and point to potential solutions to reestablish the immunological homeostasis that frequently have been lost in people living in developed societies.

Differences in gut microbiota between allergic rhinitis, atopic dermatitis, and skin urticaria: A pilot study

INTRODUCTION

Several forms of allergy have been clinically presented, including, among others, atopic dermatitis (eczema), urticaria (hives), and allergic rhinitis (rhinitis). As their detailed pathogenesis continues to be researched, we aimed in the current study to compare gut microbiota differences between eczema, hives, and rhinitis patients.

METHODS

We enrolled 19 eczemas, nine hives, and 11 allergic rhinitis patients in this study. Fecal samples were examined using 16S ribosomal ribonucleic acid amplicon sequencing, followed by bioinformatics and statistical analyses. We compared microbiota in dermatitis (eczema), chronic urticaria (hives), and allergic rhinitis (rhinitis).

RESULTS

All clinical data were similar between the subgroups. The microbiota results indicated that Bacteroidales species were found in skin allergies, both urticaria and eczema, when compared to rhinitis. The microbiota differs substantially between those patients with atopic dermatitis (eczema), chronic urticaria (hives), and allergic rhinitis (rhinitis), thus indicating that the gut-skin and gut-nose axes exist. Gut flora colonies differ significantly between skin allergy and nose allergy. Bacteroidales species could be a clinical link between gut flora and skin allergy; of those, Bacteroids Plebeius DSM 17135 is significantly associated with the urticaria (hives) subgroup.Conclusion. Our results demonstrated high intra-group homogeneous and high inter-group heterogeneous microbiota. The clinical symptoms of eczema, hives, and rhinitis can all be linked to specific microbiota in the current study. In this pilot study, the Ruminococcaceae and Bacteroidales species are associated with allergic disease, in line with several previous published articles, and the abundance of Firmicutes Phylum is representative of intestinal dysbiosis. In the future, a larger cohort and thorough biochemical studies are needed for confirmation.

The intersect of genetics, environment, and microbiota in asthma-perspectives and challenges

In asthma, a significant portion of the interaction between genetics and environment occurs through microbiota. The proposed mechanisms behind this interaction are complex and at times contradictory. This review covers recent developments in our understanding of this interaction: the "microbial hypothesis" and the "farm effect"; the role of endotoxin and genetic variation in pattern recognition systems; the interaction with allergen exposure; the additional involvement of host gut and airway microbiota; the role of viral respiratory infections in interaction with the 17q21 and CDHR3 genetic loci; and the importance of in utero and early-life timing of exposures. We propose a unified framework for understanding how all these phenomena interact to drive asthma pathogenesis. Finally, we point out some future challenges for continued research in this field, in particular the need for multiomic integration, as well as the potential utility of asthma endotyping.

Eradication of Helicobacter pylori and Gastric Cancer: A Controversial Relationship

Worldwide, gastric cancer (GC) represents the fifth cancer for incidence, and the third as cause of death in developed countries. Indeed, it resulted in more than 780,000 deaths in 2018. Helicobacter pylori appears to be responsible for the majority of these cancers. On the basis of recent studies, and either alone or combined with additional etiological factors, H. pylori is considered a "type I carcinogen." Over recent decades, new insights have been obtained into the strategies that have been adopted by H. pylori to survive the acidic conditions of the gastric environment, and to result in persistent infection, and dysregulation of host functions. The multistep processes involved in the development of GC are initiated by transition of the mucosa into chronic non-atrophic gastritis, which is primarily triggered by infection with H. pylori. This gastritis then progresses into atrophic gastritis and intestinal metaplasia, and then to dysplasia, and following Correa's cascade, to adenocarcinoma. The use of antibiotics for eradication of H. pylori can reduce the incidence of precancerous lesions only in the early stages of gastric carcinogenesis. Here, we first survey the etiology and risk factors of GC, and then we analyze the mechanisms underlying tumorigenesis induced by H. pylori, focusing attention on virulence factor CagA, inflammation, oxidative stress, and ErbB2 receptor tyrosine kinase. Moreover, we investigate the relationships between H. pylori eradication therapy and other diseases, considering not only cardia (upper stomach) cancers and Barrett's esophagus, but also asthma and allergies, through discussion of the "hygiene hypothesis. " This hypothesis suggests that improved hygiene and antibiotic use in early life reduces microbial exposure, such that the immune response does not become primed, and individuals are not protected against atopic disorders, asthma, and autoimmune diseases. Finally, we overview recent advances to uncover the complex interplay between H. pylori and the gut microbiota during gastric carcinogenesis, as characterized by reduced bacterial diversity and increased microbial dysbiosis. Indeed, it is of particular importance to identify the bacterial taxa of the stomach that might predict the outcome of gastric disease through the stages of Correa's cascade, to improve prevention and therapy of gastric carcinoma.

Advances in asthma genetics

While asthma has a strong genetic component, our current ability to systematically understand and predict asthma risk remains low, despite over a hundred genetic associations. The reasons for this unfilled gap range from technical limitations of current approaches to fundamental deficiencies in the way we understand asthma. These are discussed in the context of genomic advances.

Aspergillus fumigatus Recognition by Dendritic Cells Negatively Regulates Allergic Lung Inflammation through a TLR2/MyD88 Pathway

Aspergillus fumigatus is an opportunistic fungal pathogen responsible for a spectrum of clinical manifestations. Dendritic cells recognize pathogen-associated molecular patterns of Aspergillus via two main receptor families, Toll-like receptors (TLRs) and C-type lectin receptors (CLR). Here, the importance of TLR and CLR signaling in the regulation of T-helper cell type 2 (Th2) responses was analyzed using a mouse model based on the transfer of bone marrow-derived dendritic cells (BMDCs) pulsed with A. fumigatus conidia. BMDCs were generated from mice deficient in either MyD88 or MALT1 (mucosa-associated lymphoid tissue lymphoma translocation protein 1). Both the MyD88 and MALT1 signaling pathway in BMDCs contributed to the production of inflammatory cytokines induced by A. fumigatus conidia. Mice sensitized with MyD88^-/- BMDCs pulsed in vitro with A. fumigatus conidia showed an exacerbated allergic inflammation, with stronger eosinophil recruitment in the BAL and higher Th2 cytokine production compared with mice sensitized with wild-type or MALT1^-/- BMDCs. This exacerbation was not observed when MyD88^-/- BMDCs were pulsed with Cladosporium sphaerospermum, a nonpathogenic mold. A lack of TLR2 signaling recapitulated the exacerbation of the A. fumigatus Th2 response observed in the absence of MyD88 signaling, whereas TLR2 agonist dampened the response induced with A. fumigatus and C. sphaerospermum conidia. IL-10 production by BMDCs in response to A. fumigatus was dependent on the expression of TLR2 and MyD88. IL-10^-/- BMDCs exacerbated, whereas MyD88^-/- BMDCs supplemented with exogenous IL-10 decreased the allergic pulmonary inflammation. These results indicate that TLR2/MyD88-specific recognition of PAMPs from A. fumigatus conidia can upregulate IL-10 production and downregulate lung eosinophilia and the development of a Th2 response.

The clinical implications of the microbiome in the development of allergy diseases

Introduction: A substantial number of patients worldwide are affected by allergies. Emerging evidence suggests that the individual microbial composition might contribute to the development of allergies or might even protect from allergic diseases.Areas covered: This review provides a detailed summary regarding available knowledge on the composition of a healthy human microbiome at allergy relevant body sites. It highlights factors influencing the microbiota composition. Furthermore, recent findings on the mutual interaction of the microbiota with the innate and adaptive immune system are reported. In the final part, this knowledge is combined to discuss microbial implications for food allergy, allergic asthma, allergic rhinitis, and skin allergies. Literature for this review was gathered by searching PubMed and Google Scholar databases between October and December 2020.Expert opinion: Due to the highly individual composition, it is currently not possible to define the characteristics of a site-specific microbiome in health and disease. Mainly effects of bacterial communities have been investigated, while fungal or viral influences are not yet well understood. The communication between microbial communities found in different organs impact on allergy development. Thus, a personalized approach is essential to beneficially influence these complex interactions and to modulate the host-specific microbiota in allergies.

Microbiome of the Aerodigestive Tract in Health and Esophageal Disease

The diverse human gut microbiome is comprised of approximately 40 trillion microorganisms representing up to 1000 different bacterial species. The human microbiome plays a critical role in gut epithelial health and disease susceptibility. While the interaction between gut microbiome and gastrointestinal pathology is increasingly understood, less is known about the interaction between the microbiome and the aerodigestive tract. This review of the microbiome of the aerodigestive tract in health, and alterations in microbiome across esophageal pathologies highlights important findings and areas for future research. First, microbiome profiles are distinct along the aerodigestive tract, spanning the oral cavity to the stomach. In patients with reflux-related disease such as gastro-esophageal reflux disease, Barrett's esophagus, and esophageal adenocarcinoma, investigators have observed an overall increase in gram negative bacteria in the esophageal microbiome compared to healthy individuals. However, whether differences in microbiome promote disease development, or if these shifts are a consequence of disease remains unknown. Interestingly, use of proton pump inhibitor therapy is also associated with shifts in the microbiome, with distinct shifts and patterns along the aerodigestive tract. The relationship between the human gut microbiome and esophageal pathology is a ripe area for investigation, and further understanding of these pathways may promote development of novel targets in prevention and therapy for esophageal diseases.

Iron Dysregulation and Inflammagens Related to Oral and Gut Health Are Central to the Development of Parkinson's Disease

Neuronal lesions in Parkinson's disease (PD) are commonly associated with α-synuclein (α-Syn)-induced cell damage that are present both in the central and peripheral nervous systems of patients, with the enteric nervous system also being especially vulnerable. Here, we bring together evidence that the development and presence of PD depends on specific sets of interlinking factors that include neuroinflammation, systemic inflammation, α-Syn-induced cell damage, vascular dysfunction, iron dysregulation, and gut and periodontal dysbiosis. We argue that there is significant evidence that bacterial inflammagens fuel this systemic inflammation, and might be central to the development of PD. We also discuss the processes whereby bacterial inflammagens may be involved in causing nucleation of proteins, including of α-Syn. Lastly, we review evidence that iron chelation, pre-and probiotics, as well as antibiotics and faecal transplant treatment might be valuable treatments in PD. A most important consideration, however, is that these therapeutic options need to be validated and tested in randomized controlled clinical trials. However, targeting underlying mechanisms of PD, including gut dysbiosis and iron toxicity, have potentially opened up possibilities of a wide variety of novel treatments, which may relieve the characteristic motor and nonmotor deficits of PD, and may even slow the progression and/or accompanying gut-related conditions of the disease.

Perinatal environment shapes microbiota colonization and infant growth: impact on host response and intestinal function

BACKGROUND

Early microbial colonization triggers processes that result in intestinal maturation and immune priming. Perinatal factors, especially those associated with birth, including both mode and place of delivery are critical to shaping the infant gut microbiota with potential health consequences.

METHODS

Gut microbiota profile of 180 healthy infants (n = 23 born at home and n = 157 born in hospital, 41.7% via cesarean section [CS]) was analyzed by 16S rRNA gene sequencing at birth, 7 days, and 1 month of life. Breastfeeding habits and infant clinical data, including length, weight, and antibiotic exposure, were collected up to 18 months of life. Long-term personalized in vitro models of the intestinal epithelium and innate immune system were used to assess the link between gut microbiota composition, intestinal function, and immune response.

RESULTS

Microbiota profiles were shaped by the place and mode of delivery, and they had a distinct biological impact on the immune response and intestinal function in epithelial/immune cell models. Bacteroidetes and Bifidobacterium genus were decreased in C-section infants, who showed higher z-scores BMI and W/L during the first 18 months of life. Intestinal simulated epithelium had a stronger epithelial barrier function and intestinal maturation, alongside a higher immunological response (TLR4 route activation and pro-inflammatory cytokine release), when exposed to home-birth fecal supernatants, compared with CS. Distinct host response could be associated with different microbiota profiles.

CONCLUSIONS

Mode and place of birth influence the neonatal gut microbiota, likely shaping its interplay with the host through the maturation of the intestinal epithelium, regulation of the intestinal epithelial barrier, and control of the innate immune system during early life, which can affect the phenotypic responses linked to metabolic processes in infants.

TRIAL REGISTRATION

NCT03552939 . Video Abstract.

Maturation of the gut microbiome during the first year of life contributes to the protective farm effect on childhood asthma

Growing up on a farm is associated with an asthma-protective effect, but the mechanisms underlying this effect are largely unknown. In the Protection against Allergy: Study in Rural Environments (PASTURE) birth cohort, we modeled maturation using 16S rRNA sequence data of the human gut microbiome in infants from 2 to 12 months of age. The estimated microbiome age (EMA) in 12-month-old infants was associated with previous farm exposure (β = 0.27 (0.12-0.43), P = 0.001, n = 618) and reduced risk of asthma at school age (odds ratio (OR) = 0.72 (0.56-0.93), P = 0.011). EMA mediated the protective farm effect by 19%. In a nested case-control sample (n = 138), we found inverse associations of asthma with the measured level of fecal butyrate (OR = 0.28 (0.09-0.91), P = 0.034), bacterial taxa that predict butyrate production (OR = 0.38 (0.17-0.84), P = 0.017) and the relative abundance of the gene encoding butyryl-coenzyme A (CoA):acetate-CoA-transferase, a major enzyme in butyrate metabolism (OR = 0.43 (0.19-0.97), P = 0.042). The gut microbiome may contribute to asthma protection through metabolites, supporting the concept of a gut-lung axis in humans.

The Protective Effects of Helicobacter pylori Infection on Allergic Asthma

As an ancient Gram-negative bacterium, Helicobacter pylori has settled in human stomach. Eradicating H. pylori increases the morbidities of asthma and other allergic diseases. Therefore, H. pylori might play a protective role against asthma. The "disappearing microbiota" hypothesis suggests that the absence of certain types of the ancestral microbiota could change the development of immunology, metabolism, and cognitive ability in our early life, contributing to the development of some diseases. And the Hygiene Hypothesis links early environmental and microbial exposure to the prevalence of atopic allergies and asthma. Exposure to the environment and microbes can influence the growing immune system and protect subsequent immune-mediated diseases. H. pylori can inhibit allergic asthma by regulating the ratio of helper T cells 1/2 (Th1/Th2), Th17/regulatory T cells (Tregs), etc. H. pylori can also target dendritic cells to promote immune tolerance and enhance the protective effect on allergic asthma, and this effect relies on highly suppressed Tregs. The remote regulation of lung immune function by H. pylori is consistent with the gut-lung axis theory. Perhaps, H. pylori also protects against asthma by altering levels of stomach hormones, affecting the autonomic nervous system and lowering the expression of heat shock protein 70. Therapeutic products from H. pylori may be used to prevent and treat asthma. This paper reviews the possible protective influence of H. pylori on allergic asthma and the possible application of H. pylori in treating asthma.