Surfactant protein A explained
| surfactant, pulmonary-associated protein A1 |
| Hgncid: | 10798 |
| Symbol: | SFTPA1 |
| Altsymbols: | SFTP1 |
| Entrezgene: | 6435 |
| Omim: | 178630 |
| Refseq: | NM_005411 |
| Uniprot: | Q8IWL2 |
| Chromosome: | 10 |
| Arm: | q |
| Band: | 22.3 |
| surfactant, pulmonary-associated protein A2B |
| Hgncid: | 10799 |
| Symbol: | SFTPA2B |
| Entrezgene: | 6436 |
| Omim: | 178642 |
| Refseq: | NM_006926 |
| Uniprot: | Q8IWL1 |
| Chromosome: | 10 |
| Arm: | q |
| Band: | 22.3 |
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 (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-dependent.[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
Notes and References
- Book: Boron W, Boulpaep E . Medical Physiology . 2nd . Philadelphia . Elsevier . 2012 .
- Condon JC, Jeyasuria P, Faust JM, Mendelson CR . 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 of the United States of America . 101 . 14 . 4978–83 . April 2004 . 15044702 . 387359 . 10.1073/pnas.0401124101 . 3371804 . 2004PNAS..101.4978C . free .
- Lee DC, Romero R, Kim CJ, Chaiworapongsa T, Tarca AL, Lee J, Suh YL, Mazaki-Tovi S, Vaisbuch E, Mittal P, Draghici S, Erez O, Kusanovic JP, Hassan SS, Kim JS . Surfactant protein-A as an anti-inflammatory component in the amnion: implications for human pregnancy . Journal of Immunology . 184 . 11 . 6479–91 . June 2010 . 20439915 . 3103775 . 10.4049/jimmunol.0903867 .
- LeVine AM, Bruno MD, Huelsman KM, Ross GF, Whitsett JA, Korfhagen TR . Surfactant protein A-deficient mice are susceptible to group B streptococcal infection . Journal of Immunology . 158 . 9 . 4336–40 . May 1997 . 10.4049/jimmunol.158.9.4336 . 9126996 . free .
- LeVine AM, Kurak KE, Bruno MD, Stark JM, Whitsett JA, Korfhagen TR . Surfactant protein-A-deficient mice are susceptible to Pseudomonas aeruginosa infection . American Journal of Respiratory Cell and Molecular Biology . 19 . 4 . 700–8 . October 1998 . 9761768 . 10.1165/ajrcmb.19.4.3254 .
- van Iwaarden F, Welmers B, Verhoef J, Haagsman HP, van Golde LM . Pulmonary surfactant protein A enhances the host-defense mechanism of rat alveolar macrophages . American Journal of Respiratory Cell and Molecular Biology . 2 . 1 . 91–8 . January 1990 . 2306370 . 10.1165/ajrcmb/2.1.91 .
- Haagsman HP, Diemel RV . Surfactant-associated proteins: functions and structural variation . Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology . 129 . 1 . 91–108 . May 2001 . 11369536 . 10.1016/s1095-6433(01)00308-7.
