Clinical sepsis in neonates is responsible for the lower prevalence of developing allergy

Effect of neonatal and adult sepsis on inflammation-related diseases in multiple physiological systems: a Mendelian randomization study

Background

Long-term impact of sepsis on whole body systems is not well investigated. The aim of the study was to explore the potential association of neonatal/adult sepsis with several inflammation-related diseases in multiple physiological systems.

Methods

Instrumental variables for neonatal and adult sepsis were collected from the public genome-wide association studies, which must satisfy the correlation, exclusivity and independence assumptions. Mendelian randomization methods (including random-effect inverse-variance weighted, MR-PRESSO, weighted median and MR-Egger) were used to determine the genetic association of neonatal/adult sepsis with asthma, allergy, rheumatoid arthritis, body mass index/obesity, type 1/type 2 diabetes and intelligence/dementia. Sensitivity analyses were conducted to assess heterogeneity and horizontal pleiotropy. The study was performed by TwoSampleMR in R software.

Results

The inverse-variance weighted method reported that neonatal sepsis was related to the decreased level of body mass index (OR = 0.988, 95%CI = 0.980 ~ 0.997, P = 0.007), and adult sepsis was related to the decreased risk of obesity (OR = 0.785, 95%CI = 0.655 ~ 0.940, P = 0.009). These results were supported by the other Mendelian randomization methods. In addition, the study did not find any association of neonatal/adult sepsis with the other inflammation-related diseases. No heterogeneity and horizontal pleiotropy were found using sensitivity analyses.

Conclusion

Sepsis had the potential to reduce the risk of obesity or body mass index level at a genetic level, both in neonates and in adults.

Histologic chorioamnionitis is associated with reduced risk of late-onset sepsis in preterm infants

BACKGROUND

Histologic chorioamnionitis (HCA) is implicated in the onset of preterm labor and delivery. Chorioamnionitis is a known risk factor for early-onset sepsis and may modulate postnatal immunity. Preterm infants are at greatly increased risk of late-onset sepsis (LOS), particularly with coagulase-negative staphylococci (CoNS), but the impact of HCA on the risk of LOS is unknown.

METHODS

Eight hundred thirty-eight preterm infants born at <30 weeks gestational age at a single tertiary center were included. Histologic examination of placenta and extraplacental membranes was performed, and clinical data were extracted from hospital databases. The influence of HCA on the incidence of early-onset sepsis and LOS was examined using logistic regression analysis and Cox proportional hazards regression.

RESULTS

Mean gestational age was 26.9 ± 1.9 weeks, and mean birth weight was 936 ± 277 g. Two hundred and seventy-six (33%) of 838 infants developed LOS. The presence of fetal or maternal HCA, or maternal HCA and fetal HCA alone, was associated with a significantly decreased risk of LOS with any organism. Histologic chorioamnionitis correlated with a significantly decreased risk of CoNS LOS.

CONCLUSIONS

HCA is associated with a significantly reduced risk of acquiring LOS, both with CoNS and other bacteria. Perinatal inflammation may enhance the functional maturation of the preterm immune system and provide protection against LOS in high-risk preterm infants.

Neonatal sepsis, antibiotic therapy and later risk of asthma and allergy

Neonatal sepsis and early antibiotic therapy affect bacterial colonisation and immune activation after birth. This could have implications for later risk of allergy and asthma. Using a validated questionnaire (International Study of Asthma and Allergies in Children, ISAAC), we screened for asthma and allergy in three cohorts (total n = 834; median age 12, range 7-23 years) with different perinatal exposures as regards infection and antibiotics. Asthma, but not hay fever, was more prevalent after neonatal sepsis with adjusted odds ratio (OR) 1.63 [95% confidence interval (CI) 1.04, 2.56] and early antibiotic therapy (OR 1.48 [0.93, 2.35]) as compared with a control group. There was a trend towards increased atopic eczema after neonatal sepsis (OR = 1.39 [CI = 0.98, 1.98]). We conclude that neonatal sepsis is associated with an increased risk for later development of asthma. Early antibiotic exposure may contribute to this association.

Neonatal sepsis and later development of atopy

BACKGROUND

The role of infections on the development of atopy is still widely debated. We aimed to evaluate the effects of neonatal severe sepsis and consequent antibiotic treatment on the development of atopy and allergic diseases.

MATERIAL AND METHODS

A retrospective enrollment at school age of children with a clear history of neonatal sepsis (NS) was performed from registers of neonatal intensive care units. A normal control was assigned to each patient with sepsis. Thirty six cases with sepsis (18 males, 18 females) and 36 controls (21 males, 15 females) were selected (8.5+/-3.6 yrs). Physical examination and lung function evaluation were performed. Atopic status was verified by blood eosinophil count, total IgE serum level and skin prick tests (SPT).

RESULTS

SPT positivity for at least one allergen was present in 30% of subjects in both groups. No difference for all investigated parameters between groups and no influence by other factors such as familiarity or gender was observed. No correlation was associated to NS history.

CONCLUSIONS

Neonatal sepsis, even if clinically severe and dramatic, could represent an event too limited and really precocious in life to influence the development of immune response. Furthermore, other factors, besides infections, may influence the atopic future of newborns.

Hygiene, microbial diversity and immune regulation

PURPOSE OF REVIEW

Sanitation, antibiotics and vaccines have done more to extend life expectancy than any other medical innovation. Concern exists, however, about the link between hygiene and increased incidence of immune-mediated disorders.

RECENT FINDINGS

Studies confirm higher prevalence of asthma and allergic diseases in urban areas and developed countries rather than rural areas and developing countries. There is an inverse association between family size and disease. The debate over whether infection precipitates or prevents immune dysregulation remains a contentious one. Our knowledge about the microbial composition of the intestinal ecosystem is expanding rapidly with the introduction of molecular techniques. Differences in gut bacteria between health and atopy or inflammatory bowel disease are repeatedly reported. Recent data in inflammatory bowel disease suggest reduced species diversity and temporal instability of the gut microecosystem. The gut is a major site for induction of regulatory T cells, which secrete immunosuppressive cytokines. Not only infections, but also some commensals induce regulatory pathways, which seem to be functionally deficient in multiple sclerosis, allergies and inflammatory bowel disease.

SUMMARY

Changes in lifestyle leading to decreased exposure to certain nonpathogenic species that are important for the development of immunoregulatory mechanisms are probably associated with increased incidence of some immune-mediated diseases, such as allergies and inflammatory bowel disease.