Changes in Surfactant Protein A mRNA Levels in a Rat Model of Insulin-Treated Diabetic Pregnancy

AbstractLevels of intestinal toll-like receptor 4 (TLR4) impact inflammation in the neonatal gastrointestinal tract. While surfactant protein A (SP-A) is known to regulate TLR4 in the lung, it also reduces intestinal damage, TLR4 and inflammation in an experimental model of necrotizing enterocolitis (NEC) in neonatal rats. We hypothesized that SP-A-deficient (SP-A−/−) mice have increased ileal TLR4 and inflammatory cytokine levels compared to wild type mice, impacting intestinal physiology. We found that ileal TLR4 and proinflammatory cytokine levels were significantly higher in infant SP-A−/− mice compared to wild type mice. Gavage of neonatal SP-A−/− mice with purified SP-A reduced ileal TLR4 protein levels. SP-A reduced expression of TLR4 and proinflammatory cytokines in normal human intestinal epithelial cells (FHs74int), suggesting a direct effect. However, incubation of gastrointestinal cell lines with proteasome inhibitors did not abrogate the effect of SP-A on TLR4 protein levels, suggesting that proteasomal degradation is not involved. In a mouse model of experimental NEC, SP-A−/− mice were more susceptible to intestinal stress resembling NEC, while gavage with SP-A significantly decreased ileal damage, TLR4 and proinflammatory cytokine mRNA levels. Our data suggests that SP-A has an extrapulmonary role in the intestinal health of neonatal mice by modulating TLR4 and proinflammatory cytokines mRNA expression in intestinal epithelium.

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Antisense inhibition of surfactant protein A decreases tubular myelin formation in human fetal lung in vitro

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00410.2000 ◽

2002 ◽

Vol 282 (3) ◽

pp. L386-L393 ◽

Cited By ~ 9

Author(s):

Jonathan M. Klein ◽

Troy A. McCarthy ◽

John M. Dagle ◽

Jeanne M. Snyder

Keyword(s):

Gene Expression ◽

Protein A ◽

Fetal Lung ◽

Surfactant Protein ◽

Surfactant Protein A ◽

Mrna Levels ◽

Phosphorothioate Oligonucleotide ◽

Myelin Formation ◽

Surfactant Phospholipids ◽

Human Fetal Lung

Surfactant protein A (SP-A) is the most abundant of the surfactant-associated proteins. SP-A is involved in the formation of tubular myelin, the modulation of the surface tension-reducing properties of surfactant phospholipids, the metabolism of surfactant phospholipids, and local pulmonary host defense. We hypothesized that elimination of SP-A would alter the regulation of SP-B gene expression and the formation of tubular myelin. Midtrimester human fetal lung explants were cultured for 3–5 days in the presence or absence of an antisense 18-mer phosphorothioate oligonucleotide (ON) complementary to SP-A mRNA. After 3 days in culture, SP-A mRNA was undetectable in antisense ON-treated explants. After 5 days in culture, levels of SP-A protein were also decreased by antisense treatment. SP-B mRNA levels were not affected by the antisense SP-A ON treatment. However, there was decreased tubular myelin formation in the antisense SP-A ON-treated tissue. We conclude that selective elimination of SP-A mRNA and protein results in a decrease in tubular myelin formation in human fetal lung without affecting SP-B mRNA. We speculate that SP-A is critical to the formation of tubular myelin during human lung development and that the regulation of SP-B gene expression is independent of SP-A gene expression.

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Surfactant protein A expression is delayed in fetuses of streptozotocin-treated rats

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.1992.262.4.l489 ◽

1992 ◽

Vol 262 (4) ◽

pp. L489-L494 ◽

Cited By ~ 3

Author(s):

S. H. Guttentag ◽

D. S. Phelps ◽

W. Stenzel ◽

J. B. Warshaw ◽

J. Floros

Keyword(s):

Protein A ◽

Fetal Lung ◽

Surfactant Protein ◽

Female Rats ◽

Surfactant Protein A ◽

Mrna Levels ◽

Sprague Dawley ◽

Sprague Dawley Rats ◽

Normal Expression

The content and distribution of the 26-to 38-kDa surfactant protein (SP-A) and its mRNA were determined in fetuses of control and streptozotocin (STZ)-treated Sprague-Dawley rats using immunohistochemistry, RNA blotting, and in situ hybridization. Female rats were treated with 50 mg/kg STZ before mating, and the fetuses were killed at fetal days 18-21 or on neonatal days 1 and 2 (day of birth = end of day 22). SP-A was barely detectable on fetal day 18 in controls and easily detected by fetal day 21. In the STZ group, SP-A was decreased compared with controls at fetal days 18-21. However, by neonatal days 1–2, there were no significant differences in SP-A levels between groups. SP-A mRNA was detectable at fetal day 18 in controls, but it was decreased in the STZ group at day 18-21 (P less than 0.02) and differences were no longer detected by neonatal days 1–2. SP-A and SP-A mRNA accumulated with advancing gestational age in both groups until neonatal days 1–2. The differences in SP-A and SP-A mRNA levels in the two groups diminished with advancing age but remained significant at fetal day 21. These data suggest that STZ-induced diabetes interferes with normal expression of SP-A in the developing fetal lung.

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Expression of surfactant Protein-A in the Haemophilus influenzae -induced otitis media in a rat model

International Journal of Pediatric Otorhinolaryngology ◽

10.1016/j.ijporl.2018.06.030 ◽

2018 ◽

Vol 112 ◽

pp. 61-66 ◽

Cited By ~ 5

Author(s):

Gun Hee Yu ◽

Hee-Bok Kim ◽

Seo Hyun Ko ◽

Youn Woo Kim ◽

Yun-Sung Lim ◽

...

Keyword(s):

Haemophilus Influenzae ◽

Otitis Media ◽

Rat Model ◽

Protein A ◽

Surfactant Protein ◽

Surfactant Protein A

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Pulmonary Surfactant Protein A, B, and C mRNA and Protein Expression in the Nitrofen-Induced Congenital Diaphragmatic Hernia Rat Model

Pediatric Research ◽

10.1203/01.pdr.0000086906.19683.42 ◽

2003 ◽

Vol 54 (5) ◽

pp. 641-652 ◽

Cited By ~ 26

Author(s):

Minke van Tuyl ◽

Pietjan E Blommaart ◽

Richard Keijzer ◽

Susan E Wert ◽

Jan M Ruijter ◽

...

Keyword(s):

Protein Expression ◽

Congenital Diaphragmatic Hernia ◽

Diaphragmatic Hernia ◽

Rat Model ◽

Pulmonary Surfactant ◽

Protein A ◽

Surfactant Protein ◽

Surfactant Protein A ◽

Mrna And Protein Expression ◽

Pulmonary Surfactant Protein

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Postnatal stimulation of rat surfactant protein A synthesis by dexamethasone

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.1989.257.2.l137 ◽

1989 ◽

Vol 257 (2) ◽

pp. L137-L143 ◽

Cited By ~ 4

Author(s):

J. Floros ◽

D. S. Phelps ◽

H. P. Harding ◽

S. Church ◽

J. Ware

Keyword(s):

Protein A ◽

Hormone Treatment ◽

Surfactant Protein ◽

Surfactant Protein A ◽

Enzyme Linked Immunosorbent Assay ◽

Mrna Levels ◽

Dexamethasone Treatment ◽

Maximal Stimulation ◽

Treatment Dose

The effects of postnatal dexamethasone treatment in vivo on the synthesis of surfactant protein A (SP-A) were examined at the protein and RNA levels. Rats ranging from 1 day old to adult were injected with 200 micrograms of dexamethasone/kg body wt or with vehicle alone and were killed 24 h after injection. One portion of the lung was metabolically labeled with [35S]methionine, the proteins immunoprecipitated using an antiserum to SP-A, and analyzed electrophoretically. Both newly synthesized intracellular and secreted SP-A levels were increased by dexamethasone, reaching averages of 2.3 and 4.5 times control values, respectively. Another portion of the lung tissue was used for RNA analysis. SP-A mRNA levels were also elevated an average of 1.4 times control values by hormone treatment. Dose-response experiments using 16-day-old pups showed that both total SP-A, as measured by enzyme-linked immunosorbent assay, and total SP-A mRNA levels were elevated with dexamethasone treatment, reaching maximal stimulation at 2 mg. We conclude that postnatal dexamethasone treatment in vivo results in increased levels of both newly synthesized SP-A and SP-A mRNA, suggesting that pretranslational events may in part contribute to this process.

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Effect of genotype on the levels of surfactant protein A mRNA and on the SP-A2 splice variants in adult humans

Biochemical Journal ◽

10.1042/bj3210039 ◽

1997 ◽

Vol 321 (1) ◽

pp. 39-47 ◽

Cited By ~ 52

Author(s):

Anne M. KARINCH ◽

Daphne E. deMELLO ◽

Joanna FLOROS

Keyword(s):

Splice Variants ◽

Protein A ◽

Surfactant Protein ◽

Surfactant Protein A ◽

Northern Analysis ◽

Mrna Levels ◽

Recognition Sequence ◽

Mrna Ratio ◽

Splicing Variants ◽

Study Population

Human pulmonary surfactant protein A (SP-A) is encoded by two genes, SP-A1 and SP-A2, that exhibit coding sequence (allelic) and 5´ splicing variability. In this report we determine the effect of the genetic variability within the SP-A1 and SP-A2 genes on the level of SP-A mRNAs and on the SP-A2 splicing variants in different individuals. We analysed mRNA specimens from 23 unrelated adults using genotype analysis, Northern analysis and primer extension, and made the following observations. (1) The level of SP-A mRNA varies among individuals (coefficient of variation = 0.49). One SP-A genotype (6A26A21A01A0) appears to be associated with a low to moderate level of SP-A mRNA. (2) The SP-A1/SP-A2 mRNA ratio varies among individuals, from 0.94 (lowest) to 6.80 (highest) within the study population. One genotype appears to be associated with a moderate to high SP-A1/SP-A2 mRNA ratio and another with a low to moderate ratio. (3) There is no correlation between the level of SP-A mRNA and the SP-A1/SP-A2 mRNA ratio. (4) Variability in the ratio of the major SP-A2 splice variants among individuals results from nucleotide differences in the splice-recognition sequence of specific SP-A2 alleles. The SP-A mRNA levels, the SP-A1/SP-A2 mRNA ratio, and the ratio of the major SP-A2 splice variants have a genetic basis in that they vary depending upon the specific SP-A alleles present.

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Surfactant protein A inhibits alveolar macrophage cytokine production by CD14-independent pathway

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00427.2002 ◽

2004 ◽

Vol 286 (1) ◽

pp. L129-L136 ◽

Cited By ~ 39

Author(s):

John F. Alcorn ◽

Jo Rae Wright

Keyword(s):

Alveolar Macrophages ◽

Cytokine Production ◽

Protein A ◽

Surfactant Protein ◽

Surfactant Protein A ◽

Null Mouse ◽

Mrna Levels ◽

Wild Type ◽

Independent Manner ◽

Tnf Α

The lung collectin surfactant protein A (SP-A) has both anti-inflammatory and prophagocytic activities. We and others previously showed that SP-A inhibits the macrophage production of tumor necrosis factor (TNF)-α stimulated by the gram-negative bacterial component LPS. We propose that SP-A decreases the production of proinflammatory cytokines by alveolar macrophages via a CD14-independent mechanism. SP-A inhibited LPS-simulated TNF-α production in rat and mouse macrophages in the presence and absence of serum (72% and 42% inhibition, respectively). In addition, SP-A inhibited LPS-induced mRNA levels for TNF-α, IL-1α, and IL-1β as well as NF-κB DNA binding activity. SP-A also diminished ultrapure LPS-stimulated TNF-α produced by wild-type and CD14-null mouse alveolar macrophages by 58% and 88%, respectively. Additionally, SP-A inhibited TNF-α stimulated by PMA in both wild-type and TLR4-mutant macrophages. These data suggest that SP-A inhibits inflammatory cytokine production in a CD14-independent manner and also by mechanisms independent of the LPS signaling pathway.

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Surfactant protein A regulates cytokine production in the monocytic cell line THP-1

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.1997.272.5.l996 ◽

1997 ◽

Vol 272 (5) ◽

pp. L996-L1004 ◽

Cited By ~ 22

Author(s):

S. G. Kremlev ◽

T. M. Umstead ◽

D. S. Phelps

Keyword(s):

Cell Line ◽

Cytokine Production ◽

Protein A ◽

Surfactant Protein ◽

Surfactant Protein A ◽

Tnf Alpha ◽

Enzyme Linked Immunosorbent Assay ◽

Mrna Levels ◽

Monocytic Cell ◽

Monocytic Cell Line

Surfactant lipids inhibit cytokine production by immune cells, and surfactant protein A (SP-A) stimulates it. By enzyme-linked immunosorbent assay and mRNA blotting, we studied proinflammatory cytokine production by the monocytic cell line THP-1. SP-A caused increases in tumor necrosis factor (TNF)-alpha within 1 h, peaking at 4 h and then declining. Interleukin (IL)-1 beta increased and stayed elevated for 24 h. SP-A stimulated IL-8 also, peaking at 4 h, rapidly declining, and peaking again at 24 h. SP-A-dependent changes were detected for IL-6, but at higher SP-A doses. mRNA levels for TNF-alpha and IL-1 beta increased in response to SP-A, peaking within 2 h. The increases in TNF-alpha mRNA and protein induced by SP-A were inhibited by surfactant lipids. For IL-1 beta and IL-8, the lipids either had no inhibitory influence or inhibited less than for TNF-alpha. This suggests that the ability of macrophages to participate in inflammatory reactions is enhanced by SP-A alone or by mixtures of lipids and SP-A containing more SP-A than in normal surfactant, as occurs in many conditions leading to inflammation.

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