Cesarean delivery and risk of atopic dermatitis

Cesarean section induced dysbiosis promotes type 2 immunity but not oxazolone-induced dermatitis in mice

Delivery by cesarean section (CS) is associated with an altered gut microbiota (GM) colonization and a higher risk of later chronic inflammatory diseases. Studies investigating the association between CS and atopic dermatitis (AD) are contradictive and often biased by confounding factors. The aim of this study was therefore to provide experimental evidence for the association between CS and AD in a mouse model and clarify the role of the GM changes associated with CS. It was hypothesized that CS-delivered mice, and human CS-GM transplanted mice develop severe dermatitis due to early dysbiosis. BALB/c mice delivered by CS or vaginally (VD) as well as BALB/c mice transplanted with GM from CS or VD human donors were challenged with oxazolone on the ear. The severity of dermatitis was evaluated by ear thickness and clinical and histopathological assessment which were similar between all groups. The immune response was assessed by serum IgE concentration, local cytokine response, and presence of immune cells in the draining lymph node. Both CS-delivered mice and mice inoculated with human CS-GM had a higher IgE concentration. A higher proportion of Th2 cells were also found in the CS-GM inoculated mice, but no differences were seen in the cytokine levels in the affected ears. In support of the experimental findings, a human cohort analysis from where the GM samples were obtained found that delivery mode did not affect the children's risk of developing AD. In conclusion, CS-GM enhanced a Th2 biased immune response, but had no effect on oxazolone-induced dermatitis in mice.

Birth mode is associated with development of atopic dermatitis in infancy and early childhood

Background

Birth by caesarean section (CS) is associated with development of allergic diseases, but its role in the development of atopic dermatitis (AD) is less convincing.

Objective

Our primary aim was to determine if birth mode was associated with AD in 3-year-olds and secondarily to determine if birth mode was associated with early onset and/or persistent AD in the first 3 years of life.

Methods

We included 2129 mother-child pairs from the Scandinavian population-based prospective PreventADALL cohort with information on birth mode including vaginal birth, either traditional (81.3%) or in water (4.0%), and CS before (6.3%) and after (8.5%) onset of labor. We defined early onset AD as eczema at 3 months and AD diagnosis by 3 years of age. Persistent AD was defined as eczema both in the first year and at 3 years of age, together with an AD diagnosis by 3 years of age.

Results

AD was diagnosed at 3, 6, 12, 24, and/or 36 months in 531 children (25%). Compared to vaginal delivery, CS was overall associated with increased odds of AD by 3 years of age, with adjusted odds ratio (95% confidence interval) of 1.33 (1.02-1.74), and higher odds of early onset AD (1.63, 1.06-2.48). The highest odds for early onset AD were observed in infants born by CS after onset of labor (1.83, 1.09-3.07). Birth mode was not associated with persistent AD.

Conclusion

CS was associated with increased odds of AD by 3 years of age, particularly in infants presenting with eczema at 3 months of age.

Prevalence of eczema between cesarean-born and vaginal-born infants within 1 year of age: a systematic review and meta-analysis

This study aims to quantify the difference in prevalence of eczema between cesarean-born and vaginal-born infants within 1 year of age through a systematic review and meta-analysis. Six electronic databases were searched from inception to August 31, 2021. Studies were included if they reported the prevalence of eczema in infants within 1 year of age with specified mode of delivery. The quality of included studies was assessed using the Joanna Briggs Instrument Critical Appraisal Checklist. Pooled prevalence and odds ratio (OR) were estimated by meta-analyses of included studies. Meta-regression was conducted to explore factors affecting heterogeneity of the prevalence of eczema. Nine studies were included with 3,758 cesarean-born infants and 9,631 vaginal-born infants. The prevalence of eczema in cesarean-born infants [27.8%; 95% confidence interval (CI): 17.7-39.2] was higher than in vaginal-born infants (20.1%; 95% CI: 13.9-28.1), with a pooled OR of 1.31 (95% CI: 1.04-1.65). Subgroup analyses showed that the prevalence of eczema in cesarean-born infants varied according to country, study design, and method of ascertainment. Additionally, the pooled prevalence of eczema in vaginal-born infants differed by age at which eczema was identified. Meta-regression analysis showed that study design and eczema ascertainment method were significant sources of heterogeneity.

CONCLUSION

About 28% of cesarean-born infants within 1 year of age developed eczema, significantly higher than the 20% rate or occurrence seen in vaginal-born infants.

PROTOCOL REGISTRATION

CRD 42,020,152,437.

WHAT IS KNOWN

• Eczema, a complex inflammatory cutaneous disorder characterized by immune mediated inflammation and epidermal barrier dysfunction, is one of the most common allergic disorders in infants. • Eczema may increase the risk of immune-mediated inflammatory disease such as food allergy, asthma, and allergic rhinitis, leading to psychological and social burdens on affected individuals and their families. • Mode of delivery may be associated with the risk of developing eczema, although further studies are needed to clarify such differences.

WHAT IS NEW

• This is the first systematic review designed to estimate the prevalence of eczema in cesarean- and vaginal-born infants within 1 year of age. • Cesarean delivery may increase the risk of developing eczema in infants within the first year of life.

A new era of atopic eczema research: Advances and highlights

Atopic eczema (AE) is an inflammatory skin disease with involvement of genetic, immunological and environmental factors. One hallmark of AE is a skin barrier disruption on multiple, highly interconnected levels: filaggrin mutations, increased skin pH and a microbiome dysbiosis towards Staphylococcus aureus overgrowth are observed in addition to an abnormal type 2 immune response. Extrinsic factors seem to play a major role in the development of AE. As AE is a first step in the atopic march, its prevention and appropriate treatment are essential. Although standard therapy remains topical treatment, powerful systemic treatment options emerged in the last years. However, thorough endotyping of the individual patients is still required for ideal precision medicine approaches in future. Therefore, novel microbial and immunological biomarkers were described recently for the prediction of disease development and treatment response. This review summarizes the current state of the art in AE research.