Developmental profiles of mucosal immunity in pre-school children

Allan William Cripps: a mucosal immunologist and mentor from beginning to end

Allan Cripps was internationally recognized in the field of mucosal immunology, in particular the relationship between respiratory diseases and mucosal immunization strategies. Allan's career spanned scientific and applied research, commercialization, health education, and evolved into leadership roles in public-health and academic administration. Allan published over 400 papers and mentored over 40 research higher degree candidates. Allan was renowned for his mentorship, that did not end with the awarding of a PhD or Master's degree, but continued across a lifetime of professional engagement. Allan's key contributions to immunology included characterizing the ontogeny of the human mucosal immune system, understanding the impact of respiratory infections and otitis media in children, developing diagnostic technologies and mucosal vaccine strategies, and identifying the roles of the common mucosal immune system in human health. In this biography for the 100th anniversary of the Journal, we follow his journey of discovery and contributions to immunological research.

Influence of mouth breathing on atopic dermatitis risk and oral health in children: A population-based cross-sectional study

Background/purpose

Previous studies have suggested that mouth breathing has harmful effects on atopic dermatitis (AD) and oral health in children, but the evidence has been insufficient. To investigate the association of mouth breathing with AD and oral health in Korean schoolchildren aged 8–11 years.

Materials and methods

Cross-sectional data were obtained from March to April 2016. A questionnaire was used to investigate children's mouth breathing habits and personal/family histories related to allergic disease. Oral health status was determined through a clinical oral examination. Data were analyzed with multivariable logistic regression.

Results

In total, 1507 children were included. A moderate relationship was observed between mouth breathing and AD (adjusted odds ratio, 1.05; 95% confidence interval, 1.00–1.10; p-value, 0.035), whereas no association was found between mouth breathing and dental caries in children. Mouth breathing during sleep (MBS) was closely related to allergic diseases and other respiratory diseases. Furthermore, mouth breathing was associated with child's tonsillitis and was identified as a possible risk factor for class II dental malocclusion.

Conclusion

We confirmed the positive association between mouth breathing (especially during sleep) and allergic diseases, including the AD in school-aged children. The influence of mouth breathing on dental caries remains uncertain. An intervention trial is required to evaluate whether the prevention of mouth breathing can reduce the risk of allergic diseases.

Outdoor Endurance Training with Air Pollutant Exposure Versus Sedentary Lifestyle: A Comparison of Airway Immune Responses

Although regular exercise-training improves immune/inflammatory status, the influence of air pollutants exposure during outdoor endurance training compared to a sedentary lifestyle has not yet been clarified. This study aimed to compare the immune/inflammatory responses in the airways of street runners and sedentary people after acute and chronic particulate matter (PM) exposure. Forty volunteers (street runners (RUN, n = 20); sedentary people (SED, n = 20)) were evaluated 1 (acute) and 10 (chronic) weeks after PM exposure. Cytokines [interferon (IFN)-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-10, IL-13, and IL-17A] in nasal lavage fluid, salivary antibacterial peptides (lactoferrin (LTF), cathelicidin (LL-37), defensin-α 1-3), and secretory immunoglobulin A (SIgA), plasma club cell protein (CC16), and fractional exhaled nitric oxide (FeNO) were analyzed. After acute exposure, the RUN group showed lower levels of IL-13, IL-10, and FeNO, but higher defensin-α than the SED group. After chronic exposure, the RUN group showed elevation of IFN-γ, IL-10, IL-17A, and a decrease of FeNO levels, whereas the SED group showed elevation of TNF-α, IL-6, IL-10, and a decrease of IL-13 levels. Comparing these groups, the RUN group showed higher levels of SIgA and LTF, and lower FeNO levels than the SED group. In relation to the Th immune response analysis after acute and chronic PM exposure, the RUN group showed a pattern associated with Th1, while in the SED group, a Th2 pattern was found. Both groups showed also a Th17 immune response pattern. Our results allow us to suggest that the immune/inflammatory status of the respiratory tract after acute and chronic PM exposure was improved by the long-standing regular practice of outdoor endurance exercise compared to a sedentary lifestyle.

Immunomodulatory activity of pidotimod administered with standard antibiotic therapy in children hospitalized for community-acquired pneumonia

BACKGROUND

Several attempts to improve immune function in young children have been made and encouraging results have been collected with pidotimod (PDT), a synthetic dipeptide molecule that seems to have immunomodulatory activity on both innate and adaptive responses. Until now, the effects of PDT on the immune system have only been studied in vivo after long-term administration to evaluate whether its immunomodulatory activity might prevent the development of infections. This study was planned to evaluate the immunomodulatory activity of PDT administered together with standard antibiotic therapy in children hospitalized for community-acquired pneumonia (CAP).

METHODS

A total of 20 children hospitalized for community-acquired pneumonia (CAP) were randomized at a 1:1 ratio to receive either standard antibiotics plus pidotimod (PDT) or standard antibiotics alone to evaluate the immunomodulatory activity of PDT. Blood samples for the evaluation of immunological parameters were drawn at the time of recruitment (T0) (i.e., before therapy administration), at T3 and T5 (i.e., 3 and 5 days after the initiation of therapy) as well as at T21 (i.e., 7 days after the therapy ended).

RESULTS

Following pneumococcal polysaccharide stimulation, the percentage of dendritic cells (DCs) expressing activation and costimulatory molecules was significantly higher in children receiving PDT plus antibiotics than in the controls. A significant increase in tumor necrosis factor-α and/or interleukin-12 secretion and expression of toll like receptor 2 was observed in PDT-treated children compared with controls; this was followed by an increased release of proinflammatory cytokines by monocytes. In the PDT-treated group, mRNA expression of antimicrobial peptides and genes involved in the inflammatory response were also augmented in comparison with the controls.

CONCLUSIONS

These results demonstrate, for the first time, that PDT administered together with standard antibiotics is associated with a favorable persistent immunomodulatory effect in children with CAP.

Non-specific immune stimulation in respiratory tract infections. Separating the wheat from the chaff

Parents of children suffering from recurrent respiratory infections can be persuaded by advertisements to pressure their family physicians and pediatricians for "immune-stimulating enhancements". However, the evidence base behind these immune stimulants is usually lacking. Often there is no peer-reviewed studies available that support claims made by "immune-booster" supplements. In this review, we critically analyze most of the marketed immuno-active drugs (including vitamin preparations, dietary supplements, homeopathic remedies, Ecchinacea, bacterial lysates, and probiotics) and identify the necessity to exclude an immunodeficiency in every child suffering from recurrent respiratory tract infections.

Slow salivary secretory IgA maturation may relate to low microbial pressure and allergic symptoms in sensitized children

It is unknown why allergic symptoms do not develop in all sensitized children. We analyzed prospectively the postnatal secretory IgA (SIgA) development and whether high SIgA levels would protect sensitized infants from developing allergic symptoms. Salivary total IgA and SIgA levels were determined by ELISA, and allergy development was investigated at 3, 6, and 12 mo and at 2 and 5 y in two birth cohorts in Estonia (n = 110) and Sweden (n = 91), two geographically adjacent countries with different living conditions and allergy incidence. Total and SIgA levels increased with age, reaching adult levels at the age of 5. Virtually, all salivary IgA in Estonian children was in the secretory form, while a major part of IgA in Swedish saliva lacked the secretory component up to 2 y of age. In Sweden, high levels of salivary IgA without secretory component correlated inversely with house dust endotoxin levels. High SIgA levels were associated with less development of allergic symptoms in sensitized Swedish children. In conclusion, postnatal maturation of the salivary SIgA system proceeds markedly slower in Swedish than Estonian children, possibly as a consequence of low microbial pressure. SIgA may limit allergy-mediated tissue damage at mucosal surfaces in sensitized individuals.

Development of mucosal immunity in children: a rationale for sublingual immunotherapy?

The mucosal immune system has bidirectional tasks to mount an effective defense against invading harmful pathogens and to suppress the immune response to alimentary antigens and commensal bacterial flora. Oral tolerance is a suppression of the mucosal immune pathway related to a specific immunophenotype of the dendritic cells and an induction of the regulatory T cells as well as with the silencing of the effector T cell response by anergy and deletion. The physiological dynamic process of the anatomical and functional maturation of the immune system occurring in children during pre- and postnatal periods is a significant factor, having an impact on the fine balance between the activation and the suppression of the immune response. In this paper, mechanisms of mucosal immunity and tolerance induction in terms of maturational issues are discussed with a special emphasis on the implications for a novel therapeutic intervention in allergic diseases via the sublingual route.