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Surfactant protein levels in severe respiratory syncytial virus infection
1Department of Child Health, University of Glasgow, Royal Hospital for Sick Children, Glasgow, Scotland.
Insights
Respiratory syncytial virus (RSV) infection in infants is linked to lower levels of key surfactant proteins (SP-A, SP-B, SP-D) in the lungs. These alterations may contribute to lung dysfunction in severe RSV cases.
Area of Science:
- Pulmonary Medicine
- Pediatric Infectious Diseases
- Biochemistry
Background:
- Respiratory syncytial virus (RSV) is a primary cause of infant respiratory illness.
- Previous studies indicate reduced surfactant phospholipids in severe RSV infection.
- Surfactant proteins' role in RSV pathogenesis requires further investigation.
Purpose of the Study:
- To quantify daily levels of surfactant proteins (SP-A, SP-B, SP-D) in ventilated infants with RSV infection.
- To compare these levels with those in a control group of ventilated surgical patients.
- To explore the relationship between surfactant protein concentrations and disease severity.
Main Methods:
- Collected bronchoalveolar lavage (BAL) fluid daily from 18 infants with RSV and 16 control infants.
- Measured surfactant proteins (SP-A, SP-B, SP-D) using ELISA.
- Quantified total protein using the Lowry method and assessed disease severity via arterial alveolar oxygen ratio.
Main Results:
- Significantly reduced levels of SP-A, SP-B, and SP-D were observed in infants with RSV infection compared to controls.
- Total protein levels were elevated in the RSV group.
- No significant correlation was found between surfactant protein levels and disease severity (arterial alveolar oxygen ratio).
Conclusions:
- Alterations in surfactant protein concentrations are evident in severe RSV infection.
- Reduced surfactant proteins may play a role in the lung function abnormalities associated with RSV.
- Further research is warranted to elucidate the precise mechanisms.
Abstract:
Infection with respiratory syncytial virus (RSV) is a common cause of respiratory disease in infancy. Surfactant phospholipids have been shown to be reduced in severe RSV infection. Reduction in surfactant proteins might also contribute to the pathogenesis of this disease. We investigated daily levels of surfactant proteins in bronchoalveolar lavage (BAL) fluid from 18 ventilated infants with RSV infection (median age 3.1 mo) and in a control group of 16 ventilated surgical patients (median age 0.4 mo). Surfactant proteins were measured by ELISA, total protein by the Lowry method. Surfactant protein A (SP-A) was reduced in BAL fluid from children with RSV infection (median 5.6 micrograms/ml; range 0.6 to 151.9 micrograms/ml) compared with control samples (median 9.0 micrograms/ml; range 0.5 to 139.6 micrograms/ml, p = 0.0368). Surfactant protein B (SP-B) was lower in the RSV group (median 12.0 ng/ml; range 0 to 60. 8 ng/ml) than in control patients (median 118.1 ng/ml; range 0 to 778.2 ng/ml, p < 0.0000). Surfactant protein D (SP-D) was also reduced in the RSV group (median 130.3 ng/ml; range 0 to 1,486.0 ng/ml) versus median 600.4 ng/ml; range 0 to 1,869.0 ng/ml, p < 0. 0000. Total protein levels were higher in the RSV group (median 0.49 mg/ml; range 0.13 to 2.46 mg/ml versus median 0.36 mg/ml; range 0.07 to 1.65 mg/ml, p = 0.0079). The median value of SP-A was significantly lower in the initial sample (2.3 micrograms/ml) than in the final one (6.0 micrograms/ml). However, no significant correlation was found between surfactant protein concentrations and disease severity measured by arterial alveolar oxygen ratio. We conclude that alterations in surfactant protein concentrations are present in severe RSV infection and speculate that these may contribute to the abnormalities of lung function seen in this condition.