Pulmonary surfactant protein D in first-line innate defence against influenza A virus infections

J Innate Immun. 2013;5(3):197-208. doi: 10.1159/000346374. Epub 2013 Feb 5.

Abstract

Influenza A viruses (IAV) cause respiratory tract infections annually associated with excess mortality and morbidity. Nonspecific, innate immune mechanisms play a key role in protection against viral invasion at early stages of infection. A soluble protein present in mucosal secretions of the lung, surfactant protein D (SP-D), is an important component of this initial barrier that helps to prevent and limit IAV infections of the respiratory epithelium. This collagenous C-type lectin binds IAVs and thereby inhibits attachment and entry of the virus but also contributes to enhanced clearance of SP-D-opsonized virus via interactions with phagocytic cells. In addition, SP-D modulates the inflammatory response and helps to maintain a balance between effective neutralization/killing of IAV, and protection against alveolar damage resulting from IAV-induced excessive inflammatory responses. The mechanisms of interaction between SP-D and IAV not only depend on the structure and binding properties of SP-D but also on strain-specific features of IAV, and both issues will be discussed. SP-D from pigs exhibits distinct anti-IAV properties and is discussed in more detail. Finally, the potential of SP-D as a prophylactic and/or therapeutic antiviral agent to protect humans against infections by IAV is discussed.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Antiviral Agents / immunology
  • Antiviral Agents / therapeutic use
  • Humans
  • Immunity, Innate*
  • Influenza A virus / immunology*
  • Influenza, Human / immunology*
  • Influenza, Human / prevention & control
  • Phagocytes / immunology*
  • Pulmonary Alveoli / immunology*
  • Pulmonary Alveoli / virology
  • Pulmonary Surfactant-Associated Protein D / immunology*
  • Pulmonary Surfactant-Associated Protein D / therapeutic use

Substances

  • Antiviral Agents
  • Pulmonary Surfactant-Associated Protein D