Expression and localization of lung surfactant protein A in human tissues.
ABSTRACT Lung surfactant protein A (SP-A) is a collectin produced by alveolar type II cells and Clara cells. It binds to carbohydrate structures on microorganisms, initiating effector mechanisms of innate immunity and modulating the inflammatory response in the lung. Reverse transcriptase-polymerase chain reaction was performed on a panel of RNAs from human tissues for SP-A mRNA expression. The lung was the main site of synthesis, but transcripts were readily amplified from the trachea, prostate, pancreas, and thymus. Weak expression was observed in the colon and salivary gland. SP-A sequences derived from lung and thymus mRNA revealed the presence of both SP-A1 and SP-A2, whereas only SP-A2 expression was found in the trachea and prostate. Monoclonal antibodies were raised against SP-A and characterized. One of these (HYB 238-4) reacted in Western blotting with both reduced and unreduced SP-A, with N-deglycosylated and collagenase-treated SP-A, and with both recombinant SP-A1 and SP-A2. This antibody was used to demonstrate SP-A in immunohistochemistry of human tissues. Strong SP-A immunoreactivity was seen in alveolar type-II cells, Clara cells, and on and within alveolar macrophages, but no extrapulmonary SP-A immunoreactivity was observed. In contrast to lung surfactant protein D (SP-D), which is generally expressed on mucosal surfaces, SP-A seems to be restricted to the respiratory system.
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ABSTRACT: Beside alveoli, surface active material plays an important role in the airway physiology. In the upper airways it primarily serves in local defense. Lower airway surfactant stabilizes peripheral airways, provides the transport and defense, has barrier and edematous functions and possesses direct relaxant effect on the smooth muscle. We tested in vitro the effect of two surfactant preparations Curosurf(®) and Alveofact(®) on the precontracted smooth muscle of intra- and extra-pulmonary airways. Relaxation was more pronounced for lung tissue strip containing bronchial smooth muscle as the primary site of surfactant effect. The study does not confirm the participation of ATP-dependent potassium channels and cAMP-regulated epithelial chloride channels known as CFTR chloride channels, or nitric oxide involvement in contractile response of smooth muscle to surfactant.By controlling wall thickness and airway diameter, pulmonary surfactant is an important component of airway physiology. Thus, surfactant dysfunction may be included in pathophysiology of asthma, COPD, or other diseases with bronchial obstruction. Copyright © 2015. Published by Elsevier B.V.Respiratory Physiology & Neurobiology 01/2015; DOI:10.1016/j.resp.2015.01.004 · 1.97 Impact Factor
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ABSTRACT: Surfactant protein D (SP-D) is one of specific surfactant proteins constituting pulmonary surfactant. Recent studies have revealed that SP-D is detected in various non-pulmonary tissues and is involved in the host defense and immunomodulation. However, the relationship between SP-D and liver diseases has not yet been investigated. The aim of this study was to detect the immunolocalization of SP-D in the livers of infants with cholestatic liver disease.Methods The expression of immunoreactive SP-D was assessed in infants with cholestasis, including biliary atresia (BA, n = 7), neonatal hepatitis (NH, n = 2), and paucity of the intrahepatic bile duct (PIBD, n = 4). Immunoreactive SP-D was also assessed in six infants who died of non-liver disease as controls. Tissue samples were obtained at liver biopsy, or by post-mortem sampling. The tissue sections were incubated with anti-SP-D polyclonal antibodies and were counterstained with hematoxylin.ResultsIn the normal livers, SP-D was detected in the intrahepatic bile ducts, but was not detected in hepatocytes. In contrast, intense SP-D staining was noted in the hepatocytes from infants with BA, NH, and PIBD. Although SP-D was detected in the intrahepatic bile ducts in the infants with NH, negative or weak staining was seen in the intrahepatic bile ducts in infants with BA.Conclusion Our data showed that SP-D is present in the bile ducts of the normal infant liver, and it was found to accumulate in the hepatocytes of cholestatic livers. These results suggest that SP-D is produced in hepatocytes and is secreted into the bile ducts.Journal of Pediatric Surgery 11/2014; 50(2). DOI:10.1016/j.jpedsurg.2014.11.020 · 1.31 Impact Factor