Maternal surfactant protein A influences the immunoprotective properties of milk in a murine model

Abstract

Maternal surfactant protein A (SP-A), a collectin with innate immune system function, is critical to newborn mouse survival preventing bacterial peritonitis associated with a nonhygienic environmental exposure. We hypothesized that SP-A improves newborn survival by optimizing milk immunoprotection. Regional (lung) and systemic (milk and serum) immunologic responses to a novel antigen, 2,4-dintirophenyl keyhole limpet hemocyanin (DNP-KLH), and to a nonhygienic environment were evaluated in wild-type (WT) and SP-A null murine dams. Cross-fostering pups assessed the impact of milk on newborn survival. Maternal SP-A optimized antigen-specific milk secretory IgA (sIgA) production following the DNP-KLH exposure. Milk total and environment-specific sIgA production was not dependent on maternal SP-A in the nonhygienic exposure. At baseline, SP-A null milk contained physiologically meaningful increases in two proinflammatory cytokines compared with WT milk. The lack of SP-A plus the nonhygienic environmental exposure synergistically increased the number of proinflammatory cytokines contained in milk. Finally, the SP-A null genotype decreased pup survival during a nonhygienic environmental exposure. Maternal SP-A impacts milk sIgA and cytokine content, and is associated with improved newborn health.