Antibiotic use in children is associated with increased risk of asthma

[Implementation of the intestinal micro flora in the early stage and adequate immunity later on]

The pre and postnatal development of human immunity are remarkably continuous. The feto-placental unit builds up to promote a climate of immune tolerance specifically driven in this way by the maternal immunity. The process of birth triggers the development of the infant's postnatal immunity, in first place through the bacterial colonisation of a sterile intestinal mucosa. The progressive immune response stabilisation at the sub-mucosa level during the first year of life will arise from the interface between the host and its microflora. It will take place progressively and will occur thanks to a variety of successive and complementary very complex immune mechanisms, under the influence of a rich and diversified intestinal microbiotia. Solid scientific arguments allow hypothesising that immune deviances later in life could be the consequence of an inadequate bacterial pressure on the intestinal mucosa at the early stage. A variety of epigenetic modifications taking place in this early stage could account for the deviant programming of later immunity. Each health care provider should acknowledge that some therapeutic and nutritional interventions during the first year of life may interfere with this complex immune development, giving rise to a risk of increasing immune deviancies later on.

Infections and asthma: new insights into old ideas

A relationship between infections and allergic airway disease has long been recognized, and many reviews have been written on this topic. However, both clinical and basic science studies published in the last 3 years provide new insights into the relationship between infection and allergic conditions. In this review, we focus on these very recent studies, which address the role of infection in the development, maintenance, and exacerbation of asthma. Bacterial, viral, fungal, and parasitic infections have each been examined and provide a framework for these novel concepts.

Relation of early antibiotic use to childhood asthma: confounding by indication?

BACKGROUND

Findings from studies of the relation between early antibiotic use and subsequent asthma have been inconsistent, which may be attributable to methodologic issues.

OBJECTIVE

Our objective was to assess the impact of confounding by indication on the relation of early antibiotic use to childhood asthma through age 5 in a non-selected birth cohort (n=424).

METHODS

Oral antibiotic use was assessed by frequent nurse interviews in the first 9 months of life. Physician-diagnosed active asthma and eczema were assessed by questionnaire at 1, 2, 3, and 5 years, and were considered as ever asthma or ever eczema if positive at any age. Allergen-specific IgE was assessed in plasma at 1, 2, 3, and 5 years. Confounding by indication was investigated by considering the relation of asthma to antibiotic use while controlling for the number of illness visits to a physician in early life.

RESULTS

There was no statistically significant relation of early antibiotic use with physician-diagnosed eczema or allergen-specific IgE. A dose-response relation was evident for antibiotic use with ever asthma (odds ratio [OR]=1.5, P=0.047). Ever asthma also increased significantly with the number of illness visits to a physician (P<0.001). After adjustment for number of illness visits, antibiotic use showed no relation with asthma.

CONCLUSIONS

The relation of asthma to antibiotics in this cohort appears to be an artefact of the strong relation of number of physician visits for illness with both antibiotic use and risk for asthma.

Allergies in Asia: differences in prevalence and management compared with western populations

There is wide variability in the epidemiology and management of childhood asthma and related atopic diseases globally. Urbanized, affluent Western countries tend to have a higher prevalence of these diseases compared with Asian nations. However, recent studies have shown that the prevalence in Asia is increasing, although the rate of increase has slowed in the more developed Asian cities. Some possible causes for these differences are socioeconomic status, degree of urbanization, rates of infection, healthcare practices and genetic factors. Importantly, there are significant differences in the way asthma and allergic diseases are managed within Asia. This is of great concern because of the health implications, as these diseases are some of the most common chronic conditions that affect both adults and children. This review compares the differences in prevalence and management between Asia and the West, and discusses some of the possible reasons behind these variations.

Antibiotic use in early life and development of allergic diseases: respiratory infection as the explanation

BACKGROUND

Early antibiotic use has been postulated to increase the development of allergic disease. Antibiotic use results from infection. Early infection may play a confounding role in the relationship between antibiotic use and allergic disease.

OBJECTIVE

We aimed to investigate the relationship between antibiotic use during the first year of life and the development of allergic diseases in a birth cohort study, and also to carefully address the confounding effect of early respiratory infection.

METHODS

Three thousand three hundred and six children were included in this study who participated in investigations at all occasions of 2 months, 1, 4 and 8 years of age. Data on antibiotic use and respiratory infections were collected at the age of 1 year. Diagnoses of allergic diseases at 4 and 8 years of age were derived from the follow-up questionnaires.

RESULTS

During the first year of life, 43% (n=1420) of the children received antibiotics and 32% (n=1046) of the children had at least one type of respiratory infection among pneumonia, bronchitis and otitis. In univariate logistic regression analysis and after adjustment for early life factors, antibiotic use during the first year of life was associated with wheeze, asthma, eczema and food hypersensitivity at 4 years of age. After adjustment for the above respiratory infections during the first year of life, only the associations with wheeze and asthma at age 4 years remained statistically significant. These associations became non-significant in a subgroup analysis in children without early allergic signs. At age 8 years, antibiotic use during the first year of life was significantly associated with wheeze and eczema after adjustment for early life factors. The significant associations at age 8 years faded away following further adjustment for the respiratory infections.

CONCLUSION

Our study indicated that the association between early antibiotic use and later allergic disease could at least partially be explained by early respiratory infection.

Metagenomic analyses reveal antibiotic-induced temporal and spatial changes in intestinal microbiota with associated alterations in immune cell homeostasis

Despite widespread use of antibiotics, few studies have measured their effects on the burden or diversity of bacteria in the mammalian intestine. We developed an oral antibiotic treatment protocol and characterized its effects on murine intestinal bacterial communities and immune cell homeostasis. Antibiotic administration resulted in a 10-fold reduction in the amount of intestinal bacteria present and sequencing of 16S rDNA segments revealed significant temporal and spatial effects on luminal and mucosal-associated communities including reductions in luminal Firmicutes and mucosal-associated Lactobacillus species, and persistence of bacteria belonging to the Bacteroidetes and Proteobacteria phyla. Concurrently, antibiotic administration resulted in reduced RELM beta production, and reduced production of interferon-gamma and interleukin-17A by mucosal CD4(+) T lymphocytes. This comprehensive temporal and spatial metagenomic analyses will provide a resource and framework to test the influence of bacterial communities in murine models of human disease.

Intestinal bacteria and the regulation of immune cell homeostasis

The human intestine is colonized by an estimated 100 trillion bacteria. Some of these bacteria are essential for normal physiology, whereas others have been implicated in the pathogenesis of multiple inflammatory diseases including IBD and asthma. This review examines the influence of signals from intestinal bacteria on the homeostasis of the mammalian immune system in the context of health and disease. We review the bacterial composition of the mammalian intestine, known bacterial-derived immunoregulatory molecules, and the mammalian innate immune receptors that recognize them. We discuss the influence of bacterial-derived signals on immune cell function and the mechanisms by which these signals modulate the development and progression of inflammatory disease. We conclude with an examination of successes and future challenges in using bacterial communities or their products in the prevention or treatment of human disease.

The intestinal microbiota in health and disease: the influence of microbial products on immune cell homeostasis

PURPOSE OF REVIEW

A vast and diverse array of microbes colonizes the mammalian gastrointestinal tract. These microorganisms are integral in shaping the development and function of the immune system. Metagenomic sequencing analysis has revealed alterations in intestinal microbiota in patients suffering from chronic inflammatory diseases, including inflammatory bowel disease and asthma. This review will discuss the mechanisms through which the innate immune system recognizes and responds to the intestinal microbiota as well as the effect of specific microbiota-derived signals on immune cell homeostasis.

RECENT FINDINGS

Recent studies in murine model systems have demonstrated that manipulation of the intestinal microbiota can alter mammalian immune cell homeostasis. Specific microbial signals have been identified that can impact immune cell function both within the intestinal tract and in peripheral tissues. These microbiota-derived signals can either have an immunoregulatory effect, creating an immune state that is refractory to inflammation, or conversely, act as an adjuvant, aiding in the propagation of an immune response.

SUMMARY

Associations between alterations in the microbiota and human disease implicate intestinal microbial signals in shaping immune responses. These signals are recognized by innate immune cells and influence the ability of these cells to modulate both the local and systemic immune response.