Detection of surfactant protein A (SP-A) and surfactant protein D (SP-D) in equine synovial fluid with immunoblotting.
Abstract: Once considered unique to the lung, surfactant proteins have been clearly identified in the intestine and peritoneum and are suggested to exist in several other organs. In the lung, surfactant proteins assist in the formation of a monolayer of surface-active phospholipid at the liquid-air interface of the alveolar lining, reducing the surface tension at this surface. In contrast, surface-active phospholipid adsorbed to articular surfaces has been identified as the load-bearing boundary lubricant of the joint. This raises the question of whether surfactant proteins in synovial fluid (SF) are required for the formation of the adsorbed layer in normal joints. Proteins from small volumes of equine SF were resolved by 1- and 2-dimensional polyacrylamide gel electrophoresis and detected by Western blotting to investigate the presence of surfactant proteins. The study showed that surfactant proteins A and D (SP-A and SP-D) are present in the SF of normal horses. We suggest that, like surface-active phospholipid, SP-A and SP-D play a significant role in the functioning of joints. Next will be clarification of the roles of surfactant proteins as disease markers in a variety of joint diseases, such as degenerative joint disease and inflammatory problems. Déjà considéré comme unique au poumon, les protéines du surfactant ont clairement été identifiées dans l’intestin et le péritoine et il est suggéré qu’elles existent dans plusieurs autres organes. Dans le poumon, les protéines du surfactant aident à la formation d’une mono-couche de phospholipides tensio-actif à l’interface air-liquide à l’intérieur des alvéoles, réduisant ainsi la tension de surface à cette surface. À l’opposé, les phospholipides tensio-actifs adsorbés aux surfaces articulaires ont été identifiés comme étant un lubrifiant du support de charge de l’articulation. Ceci soulève la question à savoir si les protéines du surfactant dans le liquide synovial (SF) sont requises pour la formation de la couche adsorbée dans une articulation normale. Les protéines provenant de petites quantités de liquide synovial équin ont été analysées par électrophorèse à 1 et 2 dimensions sur gel de polyacrylamide et détectées par immunobuvardage afin d’étudier la présence de proteins du surfactant. L’étude a montré que les protéines A et D du surfactant (SP-A et SP-D) sont présentes dans le SF de chevaux normaux. Il est suggéré que, tout comme les phospholipides tensio-actifs, SP-A et SP-D jouent un rôle significatif dans le fonctionnement des articulations. Il faudra éclaircir les rôles des protéines du surfactant comme marqueurs de maladie dans un variété de maladies articulaires, telles que les maladies dégénératives des articulations et les problèmes inflammatoires. (Traduit par Docteur Serge Messier)
Publication Date: 2004-06-11 PubMed ID: 15188960PubMed Central: PMC1142159
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- Journal Article
Summary
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The study focuses on the detection of proteins, named surfactant proteins A and D (SP-A and SP-D), in the joint fluid of horses, which previously were believed to be located only in the lungs, intestine and peritoneum. The discovery implies that these proteins play a crucial role in the functioning of joints in the body, and could act as potential markers for joint diseases.
Explanation of Research
- Surfactant proteins were initially thought to be found exclusively within the lungs where they assist in maintaining the balance and reduction of surface tension at the liquid-air interface of the alveolar lining, making it crucial for healthy lung function.
- This research expands on the known existence of surfactant proteins, suggesting their presence in a variety of other organs including the intestine, peritoneum and potentially, the joints.
- The researchers decided to focus on the presence of surfactant proteins A and D (SP-A, SP-D) in synovial fluid (SF), which lubricates the joints. This idea was brought on by the identification of surface-active phospholipids (known for reducing surface tension) serving as the principal lubricant in the joints.
- The research hypothesis was that similar to surface active phospholipids, these proteins might play a significant role in the functioning of joints.
- To investigate this, equine synovial fluid was subjected to 1- and 2-dimensional polyacrylamide gel electrophoresis, a technique used to segregate proteins based on their properties. Further, the proteins were identified using Western blotting, which is a common technique to detect specific proteins within a sample.
- The results obtained confirmed the presence of SP-A and SP-D in the synovial fluid of healthy horses, posing an intriguing suggestion that they may have a role in maintaining normal joint functioning.
Implications of the Research
- The fundamental implication of this discovery is that surfactant proteins could play a much wider role in biological systems than previously thought. Particularly, their existence in synovial fluid draws attention to their potential in joint maintenance and issues related to joint health.
- This discovery opens up new avenues for further research to pinpoint the roles of SP-A and SP-D in joint function, as well as their potential as disease markers in joint-related issues such as degenerative joint disease and inflammatory problems.
Cite This Article
APA
Kankavi O, Roberts MS.
(2004).
Detection of surfactant protein A (SP-A) and surfactant protein D (SP-D) in equine synovial fluid with immunoblotting.
Can J Vet Res, 68(2), 146-149.
Publication
Researcher Affiliations
- Department of Surgery, Faculty of Veterinary Medicine, University of Kafkas, Kars 36100, Turkey. okankavi@hotmail.com
MeSH Terms
- Animals
- Blotting, Western / methods
- Blotting, Western / veterinary
- Electrophoresis, Agar Gel / veterinary
- Electrophoresis, Gel, Two-Dimensional / veterinary
- Horses / metabolism
- Joints / metabolism
- Pulmonary Surfactant-Associated Protein A / isolation & purification
- Pulmonary Surfactant-Associated Protein D / isolation & purification
- Surface-Active Agents / metabolism
- Synovial Fluid / metabolism
- Synovial Membrane / metabolism
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This article includes 17 references
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Citations
This article has been cited 4 times.- Bocking T, Singh B. Light and electron-microscopic localization of CD9 and surfactant protein A and D in normal lungs of the horse. Can J Vet Res 2021 Jul;85(3):170-176.
- Hartjen N, Bräuer L, Reiß B, Claassen H, Beileke S, Garreis F, Hoogeboom S, Tsokos M, Etzold S, Müller-Hilke B, Gelse K, Müller T, Goldring MB, Paulsen F, Schicht M. Evaluation of surfactant proteins A, B, C, and D in articular cartilage, synovial membrane and synovial fluid of healthy as well as patients with osteoarthritis and rheumatoid arthritis. PLoS One 2018;13(9):e0203502.
- Kristiansen M, Frisch M, Madsen HO, Garred P, Jacobsen S. Smoking and polymorphisms of genes encoding mannose-binding lectin and surfactant protein-D in patients with rheumatoid arthritis. Rheumatol Int 2014 Mar;34(3):373-80.
- Kankavi O. Increased expression of surfactant protein A and D in rheumatoid arthritic synovial fluid (RASF). Croat Med J 2006 Feb;47(1):155-61.
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