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Cytokines and Alveolar Type II Cells
Published in Jason Kelley, Cytokines of the Lung, 2022
SP-D is a collagenous glycoprotein that has a reduced molecular mass of 43 kd and can be isolated from rat bronchoalveolar lavage fluid, extracts of crude rat surfactant, and medium conditioned by isolated rat alveolar type II cells (Persson et al., 1988, 1989). The amino acid composition and structure of SP-D are similar to SP-A and, like SP-A, SP-D’s interaction with surfactant is calcium- and carbohydrate-dependent (Persson et al., 1989, 1990).
Medicines in neonates
Published in Evelyne Jacqz-Aigrain, Imti Choonara, Paediatric Clinical Pharmacology, 2021
Evelyne Jacqz-Aigrain, Imti Choonara
Phosphatidylcholine (PC) is the major component of pulmonary surfactant, contributing about 60% of total phospholipids [4]. DPPC is the primary surface tension lowering phospholipid (Figure 1), but it is ineffective on its own because it spreads and absorbs slowly under physiological conditions. Surfactant proteins and phosphatidylglycerol (PG) are needed for adequate spreading and adsorption in vitro and in vivo. Four surfactant-associated proteins have been identified SPA, SP-B, SP-C and SP-D [3]. They are synthesised and secreted in alveolar type II cells and clara cells. SP-A and SP-D are large hydrophilic proteins that play a role in innate immunity in the lung [3]. When natural surfactant preparations are prepared from animal lungs, using chloroform-methanol extraction, these proteins are left behind. The 2 smaller hydrophobic proteins, SP-B and SP-C, which improve spreading and adsorption of phospholipids, are present in natural surfactant preparations [5].
The Biology of the Surfactant-Associated Proteins
Published in Jacques R. Bourbon, Pulmonary Surfactant: Biochemical, Functional, Regulatory, and Clinical Concepts, 2019
In only one of the above mentioned studies was positive immunostaining of bronchial epithelial cells detected with antisera directed against one or both of the low molecular weight surfactant proteins, SP-B and SP-C.57 Several of the antisera in the studies described above may have been directed against both SP-B and SP-C; nonetheless, the staining pattern consistently observed is that of a primary localization of the low molecular weight, hydrophobic surfactant apoproteins within type II alveolar epithelial cells. These results are surprising in light of the recent report of Phelps and Floros that SP-B mRNA is detected in high concentration in epithelial cells of airways in human lung tissue.33 Further studies are needed in which SP-B and SP-C are immunolocalized and their mRNA detected by in situ hybridization in lung tissue. The localization of SP-D, the most recently described surfactant-associated protein, has not yet been described. Likewise, the ultrastructural localization of SP-B, SP-C, and SP-D have not yet been described.
A study of pneumoproteins in crystalline silica exposed rock drillers
Published in Inhalation Toxicology, 2022
Dag G. Ellingsen, Bente Ulvestad, May Britt Lund, Nils Petter Skaugset, Liv Ingunn Bjoner Sikkeland
Pneumoproteins are regarded as markers of lung injury and inflammation. Surfactant protein (SP) A (SP-A) and SP-D are mainly synthesized in alveolar type II cells (AT II) and catabolized by alveolar macrophages (AMs) and AT II (Ikegami 2006; Han and Mallampalli 2015). SP-A and SP-D have a multitude of functions, e.g. the ability to recognize and bind pathogens, attach the opsonized pathogens to phagocytic cells, and to reduce inflammation through a number of cellular receptors (Sorensen 2018; Watson et al. 2019). SP-D has also important roles in maintaining pulmonary surfactant, as shown by increased alveolar and tissue phosphatidylcholine and increased number of foamy macrophages in SP-D deficient mice (Botas et al. 1998; Korfhagen et al. 1998). One important role of SP-A in the homeostasis of surfactant is to promote surfactant uptake by pneumocytes (Nathan et al. 2016; Olmeda et al. 2017). Club cell protein 16 (CC-16) is synthesized in CCs present throughout the respiratory tract with the highest density in the respiratory bronchioles. Anti-inflammatory properties of CC-16 have been shown in mice (Laucho-Contreras et al. 2016).
A community study of the risk for obstructive sleep apnea and respiratory inflammation in an adult Chinese population
Published in Postgraduate Medicine, 2021
Cheng Zhang, Yuan Cheng, Feng Liu, Jing Ma, Guangfa Wang
IL-6 levels in the EBC were measured as an indicator of airway inflammation. In 1,189 valid EBC samples, the IL-6 level was measured in 452 randomized samples. The mean IL-6 concentration in the EBC was 10.95 ± 8.61 pg/ml in the high-risk group and 10.79 ± 10.72 pg/ml in the low-risk group. The median (min-max) was 8.15 (2.76 − 46.45) pg/ml in the high-risk group and 7.84 (0 − 84.02) pg/ml in the low-risk group. The results showed no significant difference between the two groups (p = 0.95). Plasma SP-D level was examined as an indicator of systemic inflammation in 1,064 valid samples. The mean plasma SP-D concentration was 133.36 ± 208.36 ng/ml in the high-risk group and 118.60 ± 188.29 ng/ml in the low-risk group. The median (min-max) was 49.06 (26.13 − 750.00) ng/ml in the high-risk group and 44.79 (19.8 − 750.00) ng/ml in the low-risk group. There was no significant difference between the two groups (p = 0.085) (Table 1).
KL-6 is a long-term disease-activity biomarker for interstitial lung disease associated with polymyositis/dermatomyositis, but is not a short-term disease-activity biomarker
Published in Modern Rheumatology, 2019
Masanori Hanaoka, Yasuhiro Katsumata, Hidenaga Kawasumi, Yasushi Kawaguchi, Hisashi Yamanaka
As described in Table 1, the mean baseline (i.e. before the commencement or reinforcement of immunosuppressive treatment) levels of serum KL-6 in PM/DM patients with and without ILD were 1030 U/ml (n = 39) and 304 U/ml (n = 16), respectively. The mean baseline levels of serum SP-D in PM/DM patients with and without ILD were 158 ng/ml (n = 25) and 42 ng/ml (n = 8), respectively. The baseline serum KL-6 and SP-D levels were significantly higher in PM/DM patients with ILD than in those without ILD (p < .001 in both comparisons). When established cut-off values of 500 U/mL and 110 ng/ml were applied for serum KL-6 and SP-D, respectively, their sensitivities for the diagnosis of ILD in PM/DM patients were 77% and 48%, respectively. The specificities of serum KL-6 and SP-D were both 100%. The concordance rate between elevation in KL-6 levels and diagnosis of ILD was substantial, whereas the concordance rate between elevation in SP-D levels and diagnosis of ILD was fair (Cohen’s κ = 0.66 and 0.31, respectively). The serum levels of KL-6 and SP-D were strongly correlated with each other (r = 0.69).