Effects of Rhinovirus Infection on Nasopharyngeal Bacterial Colonization in Infants With Wild or Variant Types of Mannose-Binding Lectin and Toll-Like Receptors 3 and 4

Mannose-binding lectin genotype is associated with respiratory disease in young children: A multicenter cohort study

BACKGROUND

Mannose-binding lectin (MBL) is an important component of the innate immune system. Polymorphisms in the MBL2 gene and promoter region are directly associated with MBL-deficiency. We sought to determine the association between MBL genotype on the frequency of common childhood respiratory infections, respiratory symptoms, and atopic outcomes in early childhood.

METHODS

MBL2 gene variants were analyzed in newborns recruited to the GO-CHILD multicenter prospective cohort study. Follow-up for respiratory infection and atopy diagnoses and symptoms, healthcare utilization, and medication prescription were conducted by postal questionnaires at 12 and 24 months.

RESULTS

Genotyping and follow-up were completed in 1004 children. Genotypes associated with MBL-deficiency were associated with an increased risk of bronchiolitis (relative risk [RR] 1.95, 95% confidence interval [CI] 1.33-2.85) and pneumonia (RR 2.46, 95% CI 1.16-5.22). MBL-deficient genotypes were associated with an increased risk of wheeze with shortness of breath episodes (RR 1.22, 95% CI 1.04-1.43), emergency department attendance (RR 1.90 95% CI 1.13-3.19), and hospital admission (RR 2.01, 95% CI 1.04-3.89) for wheeze. MBL-deficient genotypes were associated with a reduced risk of developing atopic dermatitis (RR 0.72, 95% CI 0.53-0.98).

CONCLUSION

The positive association between MBL-deficient genotypes and bronchiolitis and pneumonia, as well as a severe wheeze phenotype in some young children, supports the hypothesis that MBL is an important component of innate immunity in the vulnerable period before the maturation of the adaptive immune system. Identification of disease-modifying genotypes may help target preventative strategies in high-risk infants.

Acquisition and Transmission of Streptococcus pneumoniae Are Facilitated during Rhinovirus Infection in Families with Children

RATIONALE

Laboratory and clinical evidence suggests synergy between rhinoviruses and Streptococcus pneumoniae in the pathogenesis of respiratory tract infections. However, it is unclear whether rhinoviruses promote pneumococcal acquisition and transmission.

OBJECTIVES

To describe the impact of rhinovirus infection on the acquisition and transmission of pneumococci within families with children.

METHODS

We investigated 29 families with at least two children. The follow-up started at the onset of respiratory infectious symptoms in any family member and consisted of daily symptom diary and nasal swab samples from each participant twice per week for 3 weeks. Swabs were taken by the parents and sent to a study clinic by mail. Rhinoviruses were detected by reverse transcription-polymerase chain reaction and typed by sequencing. Pneumococci were identified by an antigen test and by standard culture methods, serotyping, and whole-genome sequencing. The effect of rhinovirus infection on the rates of pneumococcal acquisition and within-family transmission was estimated from the observed acquisition events and person-times spent uncolonized, using Poisson regression.

MEASUREMENTS AND MAIN RESULTS

Rhinovirus was detected in 38 subjects (30%) at the onset and in 86 subjects (67%) during the follow-up. S. pneumoniae was detected on the first day in 9 (7%) and during follow-up in 38 (30%) subjects. Children with rhinovirus infection had a 4.3-fold rate of pneumococcal acquisition from the community (95% confidence interval, 1.1-15.4) and a 14.8-fold rate of within-family transmission (95% confidence interval, 3.1-69.6) compared with children without rhinovirus infection.

CONCLUSIONS

Rhinovirus infection within families facilitates acquisition and within-family transmission of S. pneumoniae.

Polymorphisms of Mannose-binding Lectin and Toll-like Receptors 2, 3, 4, 7 and 8 and the Risk of Respiratory Infections and Acute Otitis Media in Children

BACKGROUND

Mannose-binding lectin (MBL) and toll-like receptors (TLRs) are important components of the innate immune system. We assessed the susceptibility of children with genetic variants in these factors to respiratory infections, rhinovirus infections and acute otitis media.

METHODS

In a prospective cohort study, blood samples from 381 Finnish children were analyzed for polymorphisms in MBL2 at codons 52, 54 and 57, TLR2 Arg753Gln, TLR3 Leu412Phe, TLR4 Asp299Gly, TLR7 Gln11Leu and TLR8 Leu651Leu. Children were followed up for respiratory infections until 24 months of age with daily diaries. Polymerase chain reaction and antigen tests were used for detection of respiratory viruses from nasal swabs.

RESULTS

Children with MBL variant genotype had a mean of 59 days with symptoms of respiratory infection per year, compared with 49 days in those with wild-type (P = 0.01). TLR8 polymorphisms were associated with an increased risk and TLR7 polymorphisms with a decreased risk of recurrent rhinovirus infections (P = 0.02 for both). TLR2 polymorphisms were associated with recurrent acute otitis media (P = 0.02). MBL polymorphisms were associated with an increased and TLR7 polymorphisms with a decreased risk of rhinovirus-associated acute otitis media (P = 0.03 and P = 0.006, respectively).

CONCLUSIONS

Genetic polymorphisms in MBL and TLRs promote susceptibility to or protection against respiratory infections. In addition to environmental factors, genetic variations may explain why some children are more prone to respiratory infections.