Mol. Hum. Reprod. Advance Access originally published online on October 22, 2007
Molecular Human Reproduction 2007 13(12):863-868; doi:10.1093/molehr/gam074
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Regulation of surfactant protein D in the mouse female reproductive tract in vivo
1Department of Medicine, National Jewish Medical and Research Center, Denver, CO 80206, USA 2Department of Anatomy and Cell Biology, University of Iowa College of Medicine, Iowa City, IA 52242, USA 3Department of Gynecology and Obstetrics, Emory University School of Medicine, Atlanta, GA 30303, USA 4Department of Obstetrics and Gynecology, University of Iowa College of Medicine, Iowa City, IA 52242, USA 5Department of Microbiology and Immunology, Chicago College of Osteopathic Medicine, Midwestern University, Downers Grove, IL 60515, USA
6 Correspondence address. Tel: +1-303-398-1749; Fax: +1-303-270-2249; E-mail: oberleyr{at}njc.org
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Abstract |
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Surfactant protein D (SP-D) plays a role in innate immunity in the lung and is expressed at many other mucosal surfaces throughout the human body. In this study, we show that SP-D mRNA and protein are present in the murine female reproductive tract; i.e. in the vagina, cervix, uterus and oviduct. SP-D protein is primarily localized to epithelial cells lining the genital tract and is also present in secretory material within the lumen of the uterus and cervix. The levels of SP-D mRNA in the uterus vary by a factor of 10 during the estrous cycle with peak levels present at estrus and the lowest levels at diestrus. In contrast, SP-D mRNA levels in the lung do not change during the estrous cycle. Since SP-D is an innate host defense protein present in the mouse reproductive tract, we studied the influence of infection on SP-D levels in vivo. We found that Chlamydia muridarum infection caused an increase in the SP-D protein content of reproductive tract epithelial cells. These data are suggestive that SP-D may play a role in innate immunity in the female reproductive tract in vivo.
Key words: female reproductive tract/infection/mouse/regulation/SP-D
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Introduction |
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Surfactant protein D (SP-D), a member of the collectin family of proteins, was first described in the lung (Persson et al., 1989). Collectins are a family of innate immune system proteins that bind to carbohydrates present on pathogens, in the presence of calcium (Crouch et al., 2000). SP-D has been shown to play a key role in innate host defense mechanisms in the lung (Wright, 1997). SP-D can function as an opsonin by binding to carbohydrates present on bacterial surfaces and has been shown to enhance the phagocytosis and killing of lung pathogens such as Pseudomonas aeruginosa and Klebsiella pneumoniae in vitro (Restrepo et al., 1999; Ofek et al., 2001). In contrast, SP-D can block the uptake of certain pathogens, such as Mycobacterium tuberculosis and Candida albicans, into macrophages (van Rozendaal et al., 2000; Ferguson et al., 2002). SP-D has antimicrobial activity and directly inhibits the growth of several strains of Escherichia coli, K. pneumoniae and Enterobacter aerogenes by increasing cell membrane permeability (Wu et al., 2003). Recently, it has been demonstrated that SP-D can modulate the adaptive immune response in the lung (Borron et al., 2002).
SP-D mRNA and protein have been shown to be present at many sites throughout the body, generally at mucosal surfaces (Madsen et al., 2000; Stahlman et al., 2002). Immunoreactive SP-D protein has been localized in the human female reproductive tract including in the uterus, ovaries and placenta (Madsen et al., 2000; Stahlman et al., 2002; Leth-Larsen et al., 2004). We recently reported that SP-D mRNA and protein are present in the human cervix, uterus and oviduct (Oberley et al., 2004). SP-D mRNA and protein have also been detected in the uterus and ovary of the mouse (Akiyama et al., 2002).
The female genital tract is in contact with the outside environment and thus potentially exposed to a variety of pathogens. However, relatively little is known about the innate immune system in the female reproductive tract (Wira and Fahey, 2004). The epithelial cells that line the female reproductive tract secrete defensin 5, an antimicrobial peptide that disrupts bacterial membranes (Quayle et al., 1998). It is also known that cervical glands produce several antimicrobial factors including lactoferrin, lysozyme and secretory leukoprotease inhibitor (Cohen, 1999).
Chlamydia trachomatis is a pathogen that can infect the female reproductive tract, the eye and the lung (Washington et al., 1987; Schachter, 1999). Women infected with this bacterium in the reproductive tract can develop pelvic inflammatory disease and scarring of the Fallopian tubes, conditions that can lead to infertility (Mardh and Svensson, 1982). Mothers who are infected with C. trachomatis are at risk for premature delivery and can infect their newborn infant with Chlamydia during parturition (Harrison et al., 1983). It has been shown that another collectin, mannose-binding protein (MBP), can inhibit the infection of endocervical epithelial cells (HeLa cells) by C. trachomatis in vitro (Swanson et al., 1998). However, while MBP is present in serum, it is not produced within the female reproductive tract (Swanson et al., 1998). We have recently shown that SP-D can inhibit the infection of HeLa cells by C. trachomatis in vitro (Oberley et al., 2004). On the basis of the results of these studies, we hypothesized that SP-D binds to carbohydrates present on the surface of the Chlamydia and in this way sterically hinders Chlamydia from attaching to HeLa cells (Oberley et al., 2004).
In the present study, we demonstrate that SP-D mRNA and protein are present in the epithelial cells of mouse female reproductive tissues, except in the ovary. The levels of SP-D mRNA in the uterus vary by a factor of 10 during the estrous cycle with the highest amounts present during the estrous phase of the cycle. We also show that female mice infected with Chlamydia contain increased amounts of SP-D protein in the reproductive tract. These data are suggestive that SP-D in the female reproductive tract may be involved in innate immunity in vivo.
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Animal husbandry
Female, virgin, Swiss Black mice, obtained from Taconic Laboratories, were housed in the Animal Research Facility at the University of Iowa following an institutionally approved protocol. The protocol was also approved by the institutional ethics committee. The mice were housed under controlled conditions of 12 h of light followed by 12 h of darkness and were allowed food and water ad libitum.
Estrous cycle determination
The female mice were maintained under lighting conditions such that at 6:00 lights were on and at 18:00 the lights were turned off. The vaginal smears were performed between the hours of 10:00 and 12:00. The protocol used for estrous cycle determination is similar to previously described methods (Marcondes et al., 2002; Hubscher et al., 2005; Lee and Jeung, 2007). Briefly, using a small cotton swab pre-moistened in sterile phosphate buffered saline (PBS), the vaginas of female mice (aged 2–4 months) were swabbed and the collected material smeared onto a glass slide. After the slides dried, they were immediately stained with 0.1% methylene blue for a few seconds and subsequently rinsed twice with tap water. Slides were then coverslipped and viewed using a light microscope. The cytology of the smear was used to establish the stage of the estrous cycle for each animal. Proestrus was identified by the presence of large numbers of nucleated epithelial cells with occasional polymorphonuclear leukocytes (PMNs) and cornified epithelial cells. Estrus was characterized by the predominance of cornified, non-nucleated epithelial cells in the smear. Finally, diestrus was identified by widespread PMNs with sporadic epithelial cells. The mice were sacrificed when they had reached the desired stages of the estrous cycle and the reproductive tract was dissected and tissues collected for analysis. Mice used in this study were all actively cycling over the assessment period.
Inoculation of mice with Chlamydia muridarum
Mice were infected with the mouse pathogen, C. muridarum (MoPn) Weiss strain. A week before inoculation with the Chlamydia, the female mice were injected with 2.5 mg of Depo Provera (Pharmacia, Kalamazoo, MI, USA), in order to provide a consistent and high infection rate (Cotter et al., 1997; Rank, 1999). Seven days after treatment with Depo Provera, the mice were anesthetized, and placed on their backs. Ten microlitres of MoPn (104 inclusion forming units, IFU) in PBS were placed in the vaginal vault using a micropipetter with a gel-loading tip. As a control, animals were sham inoculated with sterile PBS. Seven days after inoculation, reproductive tissues were harvested and analysed. In order to verify infection, cervical–vaginal swabs were collected in all mice at Day 7 post-infection and C. muridarum was isolated, inclusions visualized by indirect immunofluorescence and quantitated as inclusion-forming units in HeLa 229 cultures as previously described (Ramsey et al., 1999).
Immunostaining of reproductive tissues
Mouse reproductive tissues were fixed in 4% paraformaldehyde and embedded in paraffin. The tissue blocks were sectioned (7 µm thick), deparaffinized in xylenes and then rehydrated serially in 100, 95, 75 and 50% ethanol. For antigen retrieval, the slides were boiled in 0.1 M sodium citrate, pH 6.0, for 10 min and then cooled for 20 min. The slides were then rinsed in PBS and endogenous peroxidase activity quenched by incubating in 0.3% H2O2 in PBS for 30 min. Sections were rinsed with PBS and blocked by incubating in normal serum (1.5%) for 20 min, followed by incubation in a SP-D polyclonal primary antibody (rabbit anti-mouse SP-D, Chemicon, Temecula, CA, 1:1000) at 4°C overnight. For negative controls, slides were incubated overnight with normal IgG instead of the primary antibody. The slides were rinsed in PBS and incubated in secondary antibody (anti-rabbit IgG conjugated to biotin, Cappel, Aurora, OH, USA) for 30 min at room temperature. Slides were rinsed, incubated in Vectastain ABC reagent (Vector Labs, Burlingame, CA, USA) for 1 h at room temperature, rinsed again in PBS and then incubated in diaminobenzidine (0.7 mg/ml) as substrate. After a final PBS rinse followed by a H2O rinse, the sections were counterstained with hematoxylin, dehydrated and mounted using Permount. As a positive control for the SP-D staining, adult mouse lung tissue sections were also immunostained using the SP-D antibody.
Immunoblot analysis
Reproductive tissues were harvested and snap frozen in liquid nitrogen. The tissues were then homogenized in the proteinase inhibitor phenylmethyl-sulfonyl fluoride (1 mM), centrifuged at 600 x g and the supernatant collected. Protein content was determined using Bradford analysis (Bradford, 1976). Equal amounts of homogenate protein were separated by gel electrophoresis on 10% Tris–HCl polyacrylamide gels. The proteins were transferred electrophoretically at 100 V to nitrocellulose membranes and then placed in 7% non-fat dry milk diluted in 0.1% TNT (0.02 M Tris, 0.15 M NaCl, 0.1% Tween 20) overnight to block non-specific binding. The membranes were subsequently incubated with rabbit anti-SP-D primary antibody (Chemicon) at a dilution of 1:1000 for 1 h at room temperature, then washed in 0.1% TNT, three times, at 15 min per wash. The blots were incubated with a secondary antibody (anti-rabbit IgG conjugated to horseradish peroxidase, 1:10 000 (Cappel)) for 45 min at room temperature, then washed in 0.1% TNT three times at 15 min per wash and finally incubated with enhanced chemi-luminescence solution (Amersham, Buckinghamshire, UK) followed by exposure to X-ray film. To confirm equal protein loading, the nitrocellulose membranes were stained with amido black.
Real time RT-PCR analysis
RNA was isolated from mouse reproductive tissues by homogenizing the tissues in Trizol (Invitrogen, Carlsbad, CA, USA). Total RNA was extracted using chloroform and precipitated with ice-cold isopropanol. The resulting pellet was resuspended in water and quantitated by determining the absorbance at 260 nm. The quality of the RNA was determined by determining the ratio of the absorbance read at 260–280 nm (A260:A280), RNA quality was further assessed by separating the RNA on an agarose gel. Two micrograms of total RNA from each sample was then reversed transcribed. The resulting cDNAs were diluted (1/50) and replicates for each sample were aliquoted for real time polymerase chain reaction (PCR) analysis using a Stratogene Mx 3000P instrument. Primers and 6-carboxy-fluorescein (FAM)-labeled probes for mouse SP-D and 18S rRNA (a house-keeping gene) and Universal Taqman master mix were purchased from Applied Biosystems, Inc. (ABI, Foster City, CA, USA). Relative SP-D mRNA levels were assessed by the comparative quantitation method and calculated differences in mRNA expression were determined according to the manufacturer User Bulletin 2 (10/2001, ABI systems, Foster City, CA, USA). As a control, the threshold cycle (CT) values obtained from adding increasing amounts of RNA with either SP-D primers or 18S primers were plotted. The two primer sets produced parallel curves with similar slopes.
Statistics
All data were derived from at least three experiments. The data were analysed by one-way analysis of variance followed by either Student–Newman–Keuls or Dunn's Multiple Comparisons.
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SP-D mRNA and protein are present in the mouse female reproductive tract
We have previously demonstrated that SP-D mRNA and protein are present in the human female reproductive tract (Oberley et al., 2004). In order to determine the relative levels of SP-D mRNA expressed in the mouse female reproductive tract, comparative real time RT-PCR was performed on mRNA from ovary, oviduct, uterus, cervix, vagina and lung tissues collected from female Swiss Black mice (Fig. 1). All of the animals were in the proestrous stage of the estrous cycle. SP-D mRNA was detected in all of the tissues; however, the relative amount of SP-D mRNA varied (Fig. 1). The oviduct had the highest relative amount of SP-D mRNA in the female reproductive tract, whereas the uterus, cervix and vagina contained smaller and similar amounts of SP-D mRNA (Fig. 1). The female reproductive tissues had less SP-D mRNA than the lung, i.e. SP-D mRNA content in the oviduct was
4% of the content in the lung (Fig. 1). Very low amounts of SP-D mRNA were detected in the ovary. Immunoblot analysis of unstaged tissues showed that SP-D protein was present throughout the female mouse genital tract except in the ovary (Fig. 2). In agreement with the SP-D mRNA observations, the level of SP-D protein present in the mouse female reproductive tract organs was much less than in mouse lung (Fig. 2).
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Immunostaining was performed on paraffin-embedded mouse unstaged reproductive tissues in order to localize the SP-D protein (Fig. 3). SP-D was present in the epithelium of the oviduct (Fig. 3A). SP-D was also observed in the epithelium of the uterine endometrium and endometrial glands and in the epithelium of the vagina and the cervix (arrows, Fig. 3B–D). Immunoreactive SP-D protein was detected in secretory material present in the lumen of the oviduct, uterus and cervix (asterisks, Fig. 3A–C). However, there was essentially no SP-D immunostaining within the ovary (data not shown).
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SP-D expression varies during the estrous cycle
The structure and function of the epithelium in the female reproductive tract changes during the estrous cycle in response to hormonal stimuli. Therefore, we investigated the expression of SP-D in the reproductive tract as a function of the stage of the estrous cycle. Swabs of the vaginal–cervical region were obtained from 20 animals, transferred to glass slides, stained and classified as to stage of the estrous cycle. On the basis of the cytology of the smears, animals were classified as being in proestrus, estrus or diestrus (data not shown). Since the uterus undergoes the most dramatic structural changes in response to hormone levels, we decided to investigate SP-D expression levels in the uterus during different stages of the estrous cycle. Uteri and lungs were then collected from the staged animals and assayed for SP-D mRNA content using real time RT-PCR. As shown in Fig. 4, the levels of SP-D mRNA were significantly higher at estrus than at proestrus or diestrus (Fig. 4A). In contrast, the levels of SP-D mRNA in the lung did not vary with the phase of the cycle (Fig. 4B).
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Chlamydial infection increases SP-D protein production
Since SP-D has been shown to be involved in innate immunity in the lung, we were interested in determining if SP-D might also play a role in innate immunity in the female reproductive tract. Female mice were inoculated with C. muridarum (MoPn) or with PBS as a control and their cervices were harvested 7 days later and analysed for SP-D protein content (Fig. 5). Infection was confirmed at Day 7 post-infection by culture of collected cervical–vaginal swabs in HeLa 229 monolayers. The mean IFU isolated per infected mouse was approximately 105 (data not shown). In this well-established model of chlamydial infection, it has been shown that the vagina, cervix, uterus and parts of the oviduct routinely become infected 7 days post-infection (Darville et al., 1997; Morrison and Morrison, 2000). The amount of SP-D protein increased in the cervix of mice infected with Chlamydia as compared to mice that were sham infected. (Fig. 5A). Immunostaining confirmed that the cervical epithelium in chlamydial-infected animals stained more intensely for SP-D protein than the cervical epithelium in sham-infected mice (Fig. 5B, a and b). SP-D protein expression was also increased in the uterus in response to infection (Fig. 5B, c and d).
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Discussion |
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In the present study, we demonstrate that SP-D mRNA and protein are present throughout much of the murine female reproductive tract. Specifically, SP-D protein is localized to the epithelium of the vagina, cervix, uterus and oviduct. The ovary contained almost no SP-D mRNA or protein. It is noteworthy that the ovary is not as exposed to the outside environment, as other parts of the reproductive system, and may require less protection against pathogens.
SP-D is a component of innate immunity in the lung and we hypothesize that it may play a similar role in the female reproductive tract. Several components of innate immunity in the human reproductive tract, including the defensins, have been shown to vary their expression patterns during the menstral cycle (King et al., 2003). SP-D mRNA levels in the uterus varied 10-fold during the estrous cycle. In humans, the results of numerous clinical studies are suggestive that the sex hormones influence susceptibility to reproductive tract infections by many pathogens, including Chlamydia (Sonnex, 1998). In addition, women treated with oral contraceptives have been shown to have increased susceptibility to infection by Chlamydia (Washington et al., 1985). In mice, it is difficult to infect the female reproductive tract with Chlamydia during the estrous stage of the reproductive cycle (Ito et al., 1984). It is also difficult to infect ovariectomized mice with Chlamydia if they have been treated with estradiol (Kaushic et al., 2000). In the present study, we treated mice with progesterone because it caused the mice to be more susceptible to chlamydial infections. Interestingly, progesterone treatment arrests the animals in diestrus, which is also the stage where uterine SP-D levels are lowest. Thus, these observations imply that SP-D may be involved in innate defense against chlamydial bacteria.
Since estrogen levels peak late in proestrus, the observation that SP-D mRNA levels are highest during the estrous phase of the reproductive cycle in the mouse is suggestive that sex hormones, in particular estrogen, may regulate SP-D gene expression. During estrus there are very few neutrophils present within the lumen of the reproductive tract. However, in the following phase of the cycle, diestrus, many neutrophils are observed. SP-D is a known chemoattractant for neutrophils (Cai et al., 1999). Therefore, we speculate that a surge of SP-D during estrus may be related to the increased number of neutrophils present in diestrus.
Mice that are infected with MoPn in vivo increase SP-D protein production in the cervix and uterus; these results are suggestive that SP-D may be involved in host defense against chlamydial infections. Other investigators have observed that infection of the lung with Pneuomocystis carinii caused an increase in expression and accumulation of SP-D protein in lung lavage fluid; however, the mechanism by which infection results in upregulation of SP-D remains unknown (Atochina et al., 2001).
Because SP-D protein production is increased with chlamydial infections, we hypothesize that SP-D may play a role in fighting chlamydial infections. We have shown that SP-D binds to chlamydial proteins in vitro via its carbohydrate-binding domain and reduces Chlamydia infection of reproductive tract epithelial cells in vitro (Oberley et al., 2004). It is known that SP-D, at high concentrations, can directly kill some bacteria via membrane permeation (Wu et al., 2003). SP-D can also help to clear bacterial infections by acting as an opsonin to promote phagocytosis of pathogens by macrophages and neutrophils. Recently, SP-D has been shown to interact with the adaptive immune system. SP-D has been shown to enhance bacterial antigen presentation to dendritic cells, which then present the antigens to T cells, and in this way activate the adaptive immune response (Brinker et al., 2001). Therefore, SP-D may activate the adaptive immune system in the female reproductive tract when it comes in contact with Chlamydia and this may aid in efficiently resolving an infection in vivo.
In the present study, we found that SP-D, an innate immune system protein, is produced in the female reproductive tract, specifically in its mucosal lining. Within the reproductive tract, the highest levels of SP-D mRNA were present in the oviduct. The levels of SP-D in the uterus vary significantly during the estrous cycle. We demonstrate that chlamydial infection produces an increase in SP-D protein production, data suggestive that SP-D may be involved in innate immunity. We hypothesize that SP-D may act in a variety of ways to aid in the clearance of Chlamydia. SP-D may block infection of epithelial cells by the organism, directly kill the bacteria, and/or activate the adaptive immune system. These data are the first to suggest a function for SP-D protein in the female reproductive tract in vivo and one of the first studies to indicate the potential importance of innate immunity in defending against chlamydial infections.
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This project was funded by the National Institutes of Health (R01 grant HL-50050, AI49354); and a National Institutes of Health Training Grant Award #2 T32 (HL07638-16).
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The authors thank Dr Caroline George for the use of her digital camera and microscope.
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Akiyama J, Hoffman A, Brown C, Allen L, Edmondson J, Poulain F, Hawgood S. Tissue distribution of surfactant proteins A and D in the mouse. J Histochem Cytochem (2002) 50:993–996.
Atochina EN, Beck JM, Scanlon ST, Preston AM, Beers MF. Pneumocystis carinii pneumonia alters expression and distribution of lung collectins SP-A and SP-D. J Lab Clin Med (2001) 137:429–439.[CrossRef][Web of Science][Medline]
Borron PJ, Mostaghel EA, Doyle C, Walsh ES, McHeyzer-Williams MG, Wright JR. Pulmonary surfactant proteins A and D directly suppress CD3+/CD4+ cell function: evidence for two shared mechanisms. J Immunol (2002) 169:5844–5850.
Bradford MM. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem (1976) 72:248–254.[CrossRef][Web of Science][Medline]
Brinker KG, Martin E, Borron P, Mostaghel E, Doyle C, Harding CV, Wright JR. Surfactant protein D enhances bacterial antigen presentation by bone marrow-derived dendritic cells. Am J Physiol Lung Cell Mol Physiol (2001) 281:L1453–L1463.
Cai GZ, Griffin GL, Senior RM, Longmore WJ, Moxley MA. Recombinant SP-D carbohydrate recognition domain is a chemoattractant for human neutrophils. Am J Physiol (1999) 276:L131–L136.[Web of Science][Medline]
Cohen MaA D. Geritourinary mucosal surfaces. In: Sexually Transmitted Diseases—Holmes K, Sparkling P, Mardh P-A, et al, eds. (1999) New York, NY: McGraw-Hill. 173–190.
Cotter TW, Miranpuri GS, Ramsey KH, Poulsen CE, Byrne GI. Reactivation of chlamydial genital tract infection in mice. Infect Immun (1997) 65:2067–2073.
Crouch E, Hartshorn K, Ofek I. Collectins and pulmonary innate immunity. Immunol Rev (2000) 173:52–65.[CrossRef][Web of Science][Medline]
Darville T, Andrews CW Jr, Laffoon KK, Shymasani W, Kishen LR, Rank RG. Mouse strain-dependent variation in the course and outcome of chlamydial genital tract infection is associated with differences in host response. Infect Immun (1997) 65:3065–3073.
Ferguson JS, Voelker DR, Ufnar JA, Dawson AJ, Schlesinger LS. Surfactant protein D inhibition of human macrophage uptake of Mycobacterium tuberculosis is independent of bacterial agglutination. J Immunol (2002) 168:1309–1314.
Harrison HR, Alexander ER, Weinstein L, Lewis M, Nash M, Sim DA. Cervical Chlamydia trachomatis and mycoplasmal infections in pregnancy. Epidemiology and outcomes. JAMA (1983) 250:1721–1727.
Hubscher CH, Brooks DL, Johnson JR. A quantitative method for assessing stages of the rat estrous cycle. Biotech Histochem (2005) 80:79–87.[CrossRef][Web of Science][Medline]
Ito JI Jr, Harrison HR, Alexander ER, Billings LJ. Establishment of genital tract infection in the CF-1 mouse by intravaginal inoculation of a human oculogenital isolate of Chlamydia trachomatis. J Infect Dis (1984) 150:577–582.[Web of Science][Medline]
Kaushic C, Zhou F, Murdin AD, Wira CR. Effects of estradiol and progesterone on susceptibility and early immune responses to Chlamydia trachomatis infection in the female reproductive tract. Infect Immun (2000) 68:4207–4216.
King AE, Critchley HO, Kelly RW. Innate immune defences in the human endometrium. Reprod Biol Endocrinol (2003) 1:116.[CrossRef][Medline]
Lee GS, Jeung EB. Uterine TRPV6 expression during the estrous cycle and pregnancy in a mouse model. Am J Physiol Endocrinol Metab (2007) 293:E132–E138.
Leth-Larsen R, Floridon C, Nielsen O, Holmskov U. Surfactant protein D in the female genital tract. Mol Hum Reprod (2004) 10:149–154.
Madsen J, Kliem A, Tornoe I, Skjodt K, Koch C, Holmskov U. Localization of lung surfactant protein D on mucosal surfaces in human tissues. J Immunol (2000) 164:5866–5870.
Marcondes FK, Bianchi FJ, Tanno AP. Determination of the estrous cycle phases of rats: some helpful considerations. Braz J Biol (2002) 62:609–614.[Medline]
Mardh PA, Svensson L. Chlamydial salpingitis. Scand J Infect Dis Suppl (1982) 32:64–72.[Medline]
Morrison SG, Morrison RP. In situ analysis of the evolution of the primary immune response in murine Chlamydia trachomatis genital tract infection. Infect Immun (2000) 68:2870–2879.
Oberley RE, Goss KL, Ault KA, Crouch EC, Snyder JM. Surfactant protein D is present in the human female reproductive tract and inhibits Chlamydia trachomatis infection. Mol Hum Reprod (2004) 10:861–870.
Ofek I, Mesika A, Kalina M, Keisari Y, Podschun R, Sahly H, Chang D, McGregor D, Crouch E. Surfactant protein D enhances phagocytosis and killing of unencapsulated phase variants of Klebsiella pneumoniae. Infect Immun (2001) 69:24–33.
Persson A, Chang D, Rust K, Moxley M, Longmore W, Crouch E. Purification and biochemical characterization of CP4 (SP-D), a collagenous surfactant-associated protein. Biochemistry (1989) 28:6361–6367.[CrossRef][Web of Science][Medline]
Quayle AJ, Porter EM, Nussbaum AA, Wang YM, Brabec C, Yip KP, Mok SC. Gene expression, immunolocalization, and secretion of human defensin-5 in human female reproductive tract. Am J Pathol (1998) 152:1247–1258.[Abstract]
Ramsey KH, Cotter TW, Salyer RD, Miranpuri GS, Yanez MA, Poulsen CE, DeWolfe JL, Byrne GI. Prior genital tract infection with a murine or human biovar of Chlamydia trachomatis protects mice against heterotypic challenge infection. Infect Immun (1999) 67:3019–3025.
Rank RG. Models in Immunity. In: In Chlamydia: Intacellular Biology, Pathogenesis, and Immunity—Stephens RS, ed. (1999) Washington, DC: American Society for Microbiology. 239–295.
Restrepo CI, Dong Q, Savov J, Mariencheck WI, Wright JR. Surfactant protein D stimulates phagocytosis of pseudomonas aeruginosa by alveolar macrophages. Am J Respir Cell Mol Biol (1999) 21:576–585.
Schachter J. Infection and Disease Epidemiology Chapter 6. In: Chlamydia: Intracellular Biology, Pathogenesis, and Immunity—Stephens RS, ed. (1999) American Society for Microbiology Press. 139–169.
Sonnex C. Influence of ovarian hormones on urogenital infection. Sex Transm Infect (1998) 74:11–19.[Abstract]
Stahlman MT, Gray ME, Hull WM, Whitsett JA. Immunolocalization of surfactant protein-D (SP-D) in human fetal, newborn, and adult tissues. J Histochem Cytochem (2002) 50:651–660.
Swanson AF, Ezekowitz RA, Lee A, Kuo CC. Human mannose-binding protein inhibits infection of HeLa cells by Chlamydia trachomatis. Infect Immun (1998) 66:1607–1612.
van Rozendaal BA, van Spriel AB, van De Winkel JG, Haagsman HP. Role of pulmonary surfactant protein D in innate defense against Candida albicans. J Infect Dis (2000) 182:917–922.[CrossRef][Web of Science][Medline]
Washington AE, Johnson RE, Sanders LL Jr. Chlamydia trachomatis infections in the United States. What are they costing us? JAMA (1987) 257:2070–2072.
Washington AE, Gove S, Schachter J, Sweet RL. Oral contraceptives, Chlamydia trachomatis infection, and pelvic inflammatory disease. A word of caution about protection. JAMA (1985) 253:2246–2250.
Wira CR, Fahey JV. The innate immune system: gatekeeper to the female reproductive tract. Immunology (2004) 111:13–15.[CrossRef][Web of Science][Medline]
Wright JR. Immunomodulatory functions of surfactant. Physiol Rev (1997) 77:931–962.
Wu H, Kuzmenko A, Wan S, Schaffer L, Weiss A, Fisher JH, Kim KS, McCormack FX. Surfactant proteins A and D inhibit the growth of Gram-negative bacteria by increasing membrane permeability. J Clin Invest (2003) 111:1589–1602.[CrossRef][Web of Science][Medline]
Submitted on September 13, 2007; accepted on September 21, 2007.
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