Breastfeeding reduces immune activation in primary respiratory syncytial virus infection.

In epidemiological studies of respiratory syncytial virus (RSV) disease, breast milk has proven to be beneficial. However, a host mechanism that is associated with both disease severity and that is capable of being modulated by breast milk, has not yet been identified. Both the predominance of interleukin-10 (IL-10) over interferon-gamma (IFN-gamma), and high soluble interleukin-2 receptor antagonist (sCD25) concentrations have been associated with RSV severity. We explored if they were modulated by breastfeeding. Previously healthy Chilean infants from Santiago with RSV infection (n = 349) were consecutively enrolled in the study if they were term births, without underlying pathology. Breastfeeding was described as absent or present, and if partial or exclusive. Immune response was expressed through plasma concentrations of IFN-gamma, IL-10 and sCD25, obtained both in the acute and the recovery phase. The acute phase sCD25 concentrations were lower in the breastfed (13.8 ng/mL, n =133), compared with the non-breastfed infants (15.9 ng/mL, n 27, p = 0.015). The difference increased in infants below 3 months of age (p = 0.006) and with exclusive (p = 0.004), compared to partial breastfeeding (p = 0.025). When analyzed together with age, sex, severity and environment, breastfeeding was the only independent predictor of high sCD25 concentrations (above mean + 1SD, OR 4.6, 95% CI 1.8-11.9, p = 0.0015). The recovery phase IFN-gamma/IL-10 ratio was higher in the breastfed infants, but when analyzed with potential confounding factors, only female sex was associated with an increased ratio (OR 2.32, 95% CI 1.02-5.29, p = 0.045). High sCD25 concentrations during the acute phase of infection, previously associated with severe RSV disease, were significantly and independently reduced in association with breastfeeding, whereas the Th1/Th3 balance was only modified in the recovery phase.

Plasma interferon-gamma, interleukin-10 and soluble markers of immune activation in infants with primary adenovirus (ADV) and respiratory syncytial virus (RSV) infection.

Adenovirus (ADV) and respiratory syncytial virus (RSV) are etiological agents of acute respiratory tract infection in infants. Long-term prognosis of ADV infection includes severe lung damage, bronchiectasis and hyperlucent lung, while RSV infection is associated with development of recurrent wheezing and subsequent asthma. These differences may be related to differences in the primary immune responses elicited by these viruses. In this paper, we investigated the type of cytokine responses and the magnitude of immune activation in ADV and RSV infections in infants. We examined plasma concentrations of interferon-gamma (IFN-gamma), interleukin-10 (IL-10), soluble interleukin-2 receptor (sCD25) and soluble tumor necrosis factor receptor II (sTNFR-II) in previously healthy infants during the acute phase of primary ADV infection (n = 21) and RSV infection (n = 68), and in uninfected controls (n = 44). In ADV-infected infants, IFN-gamma plasma levels were significantly higher than those observed in RSV cases and the control group (p < 0.05). RSV cases did not show any differences in IFN-gamma plasma levels compared to the other groups. sCD25 levels were significantly higher in ADV- and RSV-infected infants than in controls (p < 0.0001), and higher in ADV than in RSV cases (p < 0.05). sTNFR-II levels were significantly higher in RSV- and ADV-infected infants than in controls (p < 0.0001, p < 0.05, respectively), and higher in RSV than in ADV infection (p < 0.05). No significant differences were observed in IL-10 plasma concentrations between the three groups. These results indicate that ADV and RSV infections in infants differ significantly with regard to the magnitude of production of interferon-gamma and soluble immune activation markers sCD25 and sTNFR-II. These immunological differences may be involved in the different clinical outcomes associated with these viral infections.