Surfactant protein A

surfactant, pulmonary-associated protein A1
Identifiers
Symbol SFTPA1
Alt. symbols SFTP1
Entrez 6435
HUGO 10798
OMIM 178630
RefSeq NM_005411
UniProt Q8IWL2
Other data
Locus Chr. 10 q22.3
surfactant, pulmonary-associated protein A2B
Identifiers
Symbol SFTPA2B
Entrez 6436
HUGO 10799
OMIM 178642
RefSeq NM_006926
UniProt Q8IWL1
Other data
Locus Chr. 10 q22.3

Surfactant protein A is an innate immune system collectin. It is water soluble and has collagen-like domains similar to SP-D. It is part of the innate immune system and is used to opsonize bacterial cells in the alveoli marking them for phagocytosis by alveolar macrophages. SP-A may also play a role in negative feedback limiting the secretion of pulmonary surfactant. SP-A is not required for pulmonary surfactant to function but does confer immune effects to the organism.[1]

During Parturition

The role of Surfactant protein A (or SP-A) in childbirth is indicated in studies with mice.[2] Mice which gestate for 19 days typically show signs of SP-A in amniotic fluid at around 16 days. If SP-A is injected into the uterus at 15 days, mice typically deliver early. Inversely, an SP-A inhibitor injection causes notable delays in birth.

The presence of Surfactant Protein A seemed to trigger an inflammatory response in the uterus of the mice, but later studies found an anti-inflammatory response in humans.[3] In fact, the level of SP-A in a human uterus typically decreases during labor.

Immune Functions

Research on SP-A has been done mainly in rodents including mice and rats. This research has shown that mice deficient in SP-A are more susceptible to infections from group B Streptoccoal organisms,[4] Pseudomonas aeruginosa,[5] and likely other organisms. The immune functions of SP-A are time, temperature, and concentration dependant.[6]

Location

SP-A is found in the pulmonary surfactant in lungs. SP-A and SP-D are also present in extrapulmonary tissues.[7]

See also

External links

References

  1. ↑ Boron W, Boulpaep E. Medical Physiology. 2nd ed. Philadelphia: Elsevier; 2012.
  2. ↑ Condon, Jennifer C.; Jeyasuria, Pancharatnam; Faust, Julie M.; Mendelson, Carole R. (2004). "Surfactant protein secreted by the maturing mouse fetal lung acts as a hormone that signals the initiation of parturition". Proceedings of the National Academy of Sciences 101 (14): 4978–83. doi:10.1073/pnas.0401124101. JSTOR 3371804. PMC 387359. PMID 15044702.
  3. ↑ Lee, Deug-Chan; Romero, Roberto; Kim, Chong Jai; Chaiworapongsa, Tinnakorn; Tarca, Adi L.; Lee, JoonHo; Suh, Yeon-Lim; Mazaki-Tovi, Shali et al. (2010). "Surfactant Protein-A as an Anti-Inflammatory Component in the Amnion: Implications for Human Pregnancy". The Journal of Immunology 184 (11): 6479–91. doi:10.4049/jimmunol.0903867. PMC 3103775. PMID 20439915.
  4. ↑ http://www.jimmunol.org/content/158/9/4336.short
  5. ↑ http://europepmc.org/abstract/MED/9761768
  6. ↑ http://europepmc.org/abstract/MED/2306370/
  7. ↑ Haagsman, HP; Diemel, RV (May 2001). "Surfactant-associated proteins: functions and structural variation". Comp Biochem Physiol A Mol Integr Physiol 129 (1): 91–108. PMID 11369536.