Placental histology for targeted risk assessment of recurrent spontaneous preterm birth.

BACKGROUND: Spontaneous preterm birth significantly increases the risk for a recurrent preterm birth. Only a few identifiable clinical risk factors can be referenced in counseling for recurrent preterm birth. Furthermore, treatment using progesterone supplementation has not consistently prevented preterm birth among high-risk patients, but it may be effective in a subset of those patients. Placental pathology from a previous pregnancy may be used to predict which patients will experience a recurrent preterm birth or to identify a subset of patients more likely to respond to treatment with antenatal progesterone. OBJECTIVE: This study aimed to determine if histologic patterns are associated with recurrent preterm birth among patients with an index spontaneous preterm birth. A secondary objective was to determine if placental histologic types and/or progesterone receptor density in the decidua are associated with the response to progesterone supplementation with intramuscular 17-hydroxyprogesterone caproate. STUDY DESIGN: This was a retrospective cohort study at a single institution of women with singleton pregnancies with an index spontaneous preterm birth and a subsequent birth within the same hospital system between 2009 and 2019. Patients were included if placental pathology was available for the index spontaneous preterm birth. A logistic regression was used to determine if there were independent associations between 4 histologic types (acute inflammation, maternal vascular malperfusion, fetal vascular malperfusion, chronic inflammation) and recurrent preterm birth. For the secondary endpoint, 17-hydroxyprogesterone caproate response was defined as prolonging gestation by >3 weeks beyond the gestational age at delivery in the index pregnancy. Patients who delivered <3 weeks beyond the gestational age in the index pregnancy but at ≥39 weeks' gestation were excluded. A logistic regression was used to assess the independent association between placental histology and 17-hydroxyprogesterone caproate response. Sensitivity analyses were completed using only patients with an index birth <36 weeks' gestation, and then excluding those with medically indicated preterm birth in a subsequent pregnancy. A nested case-control immunohistochemical study was done among 20 patients with a subsequent term birth and 20 patients with a subsequent spontaneous preterm birth. The percentage of cells in the maternal decidua positive for progesterone receptors was correlated with the subsequent pregnancy outcome. RESULTS: A total of 352 patients were included. Acute inflammation was the most common histologic type seen among patients with spontaneous preterm birth (44.1%), followed by chronic inflammation (40.9%) and maternal vascular malperfusion (31.3%). No histologic type was independently associated with recurrent preterm birth. A total of 155 patients received 17-hydroxyprogesterone caproate in a second pregnancy. Low-grade acute inflammation was significantly associated with a decreased likelihood of 17-hydroxyprogesterone caproate response. Low-grade maternal vascular malperfusion among those with an index pregnancy delivered at <36 weeks' gestation was significantly associated with a more than 4 times increased likelihood of 17-hydroxyprogesterone caproate response when excluding those with a subsequent iatrogenic preterm birth. Progesterone receptor staining was not associated with recurrent preterm birth. CONCLUSION: Although acute inflammation was prevalent among spontaneous preterm births, more than half of the spontaneous preterm births were not associated with acute inflammation. Low-grade acute inflammation was associated with a significantly decreased response to 17-hydroxyprogesterone caproate supplementation. Low-grade maternal vascular malperfusion was associated with a 4-fold increased likelihood of 17-hydroxyprogesterone caproate response among those with index deliveries <36 weeks' gestation. Further work is needed to determine if placental pathologic examination can be used to target treatment in subsequent pregnancies to prevent recurrent preterm birth.

Is human labor at term an inflammatory condition?†.

Parturition at term in normal pregnancy follows a predictable sequence of events. There is some evidence that a state of inflammation prevails in the reproductive tissues during labor at term, but it is uncertain whether this phenomenon is the initiating signal for parturition. The absence of a clear temporal sequence of inflammatory events prior to labor casts doubt on the concept that normal human labor at term is primarily the result of an inflammatory cascade. This review examines evidence linking parturition and inflammation in order to address whether inflammation is a cause of labor, a consequence of labor, or a separate but related phenomenon. Finally, we identify and suggest ways to reconcile inconsistencies regarding definitions of labor onset in published research, which may contribute to the variability in conclusions regarding the genesis and maintenance of parturition. A more thorough understanding of the processes underlying normal parturition at term may lead to novel insights regarding abnormal labor, including spontaneous preterm labor, preterm premature rupture of the fetal membranes, and dysfunctional labor, and the role of inflammation in each.

Glucose Testing in an Index Pregnancy and Outcomes in a Subsequent Pregnancy: Implications for Screening and a Novel Risk Calculator.

OBJECTIVE: Our objective was to assess whether variables from an index pregnancy (PG1) can be used to guide testing for gestational diabetes mellitus (GDM) in a subsequent pregnancy (PG2) and to create a risk calculator for GDM in PG2. STUDY DESIGN: This was a retrospective cohort study of patients delivering ≥2 singleton gestations at >24 weeks' gestation from June 2009 to December 2018, for whom results of a 1-hour glucose challenge test (GCT) were available from PG1. Univariable and multivariable analyses were performed to evaluate factors associated with GDM in PG2. RESULTS: In total, 4,278 patients met the inclusion criteria. Among patients with a normal 1-hour GCT (<140 mg/dL) in PG1 (n = 3,719), 3.9% were diagnosed with GDM in PG2. In multivariable analysis of this group, GDM in PG2 was associated with higher GCT in PG1 (adjusted odds ratio [aOR]: 1.05, 95% confidence interval [CI]: 1.04-1.06), large for gestational age neonate in PG1 (aOR: 1.97, 95% CI: 1.24-3.13), and higher BMI (aOR: 1.08, 95% CI: 1.05-1.11). A novel risk calculator for GDM in PG2 was developed based on these associations. Using a risk cut-off of 15%, the calculator had a positive predictive value of 26% and a negative predictive value of 97%, with 3.2% of patients identified as "at risk". Among patients with abnormal 1-hour GCT in PG1, 38.3% (n = 214/559) had an abnormal 1-hour GCT in PG2 and 34.5% (n = 74/214) of these patients received a diagnosis of GDM. CONCLUSION: A normal 1-hour GCT in an PG1 is followed by GDM in a subsequent pregnancy in only 3.9% of cases. A novel calculator supports replacing universal screening with targeted testing in subsequent pregnancies in this population. Among patients with an abnormal 1-hour GCT in PG1, nearly 40% have an abnormal 1-hour GCT in a subsequent pregnancy. Direct diagnostic testing can be considered in such patients. KEY POINTS: · Normal GCT in a first pregnancy is associated with normal GCT in subsequent pregnancy.. · A risk calculator can target diabetes testing in a subsequent pregnancy.. · Abnormal GCT in a first pregnancy is associated with abnormal GCT in subsequent pregnancy..

Toxic effects of trace phenol/guanidine isothiocyanate (P/GI) on cells cultured nearby in covered 96-well plates.

BACKGROUND: A mixture of phenol and guanidine isothiocyanate ("P/GI", the principal components of TRIzol™ and similar products) is routinely used to isolate RNA, DNA, and proteins from a single specimen. In time-course experiments of cells grown in tissue culture, replicate wells are often harvested sequentially and compared, with the assumption that in-well lysis and complete aspiration of P/GI has no effect on continuing cultures in nearby wells. METHODS: To test this assumption, we investigated morphology and function of RAW 264.7 cells (an immortalized mouse macrophage cell line) cultured in covered 96-well plates for 4, 8, or 24 h at varying distances from a single control well or a well into which P/GI had been deposited and immediately aspirated completely. RESULTS: Time- and distance-dependent disruptions resulting from proximity to a single well containing trace residual P/GI were seen in cell morphology (blebbing, cytoplasmic disruption, and accumulation of intracellular vesicles), cell function (pH of culture medium), and expression of genes related to inflammation (Tnfα) and autophagy (Lc3b). There was no transcriptional change in the anti-apoptotic gene Mcl1, nor the pro-apoptotic gene Hrk, nor in P/GI-unexposed control cultures. LPS-stimulated cells incubated near P/GI had lower expression of the cytokine Il6. These effects were seen as early as 4 h of exposure and at a distance of up to 3 well units from the P/GI-exposed well. CONCLUSIONS: Exposure to trace residual quantities of P/GI in covered tissue culture plates leads to substantial disruption of cell morphology and function in as little as 4 h, possibly through induction of autophagy but not apoptosis. This phenomenon should be considered when planning time-course experiments in multi-well covered tissue culture plates.

A comprehensive analysis of the association between placental pathology and recurrent preterm birth.

BACKGROUND: Histologic examination of the placenta is often performed after preterm birth. Although placental examination cannot change the index pregnancy outcome, it may inform the risk of adverse outcomes in a subsequent pregnancy. Previous research has examined the association between individual histologic lesions and pregnancy outcomes without consistent results. OBJECTIVE: This study aimed to determine the independent contributions of the major placental pathology histologic types to recurrent preterm birth. STUDY DESIGN: This was a retrospective cohort study of deliveries at a tertiary care center from January 2009 to March 2018. Individuals with ≥2 births, an index birth of <37 weeks of gestation, and a placental pathology report from the index pregnancy were included. The presence of maternal vascular malperfusion, fetal vascular malperfusion, acute inflammation, and chronic inflammation was extracted from the pathology reports for each index placenta and classified as none, low grade, or high grade. A log-binomial model incorporating all 4 placental pathology histologic types, index gestational age, race, and maternal age was used to estimate the associations between each placental histologic type and risk of recurrent preterm birth. Moreover, 2-way interaction terms were studied among placental histologic types. In addition, 2 stratified analyses were completed on the basis of characteristics of the index preterm birth: (1) by late preterm (gestational age of 34-36 weeks) vs early-to-moderate preterm birth (<34 weeks) and (2) a subgroup analysis of those with spontaneous preterm birth. RESULTS: A total of 924 pregnancy pairs met the inclusion criteria. Only high-grade chronic inflammation was independently associated with an increased risk of recurrent preterm birth (adjusted risk ratio, 1.37; 95% confidence interval, 1.03-1.81). Stratified analysis by gestational age group demonstrated maternal vascular malperfusion was associated with recurrent preterm birth only among those with early preterm birth (adjusted risk ratio, 1.40; 95% confidence interval, 1.01-1.93). Among participants with spontaneous preterm labor, no association was found between pathology histologic types and risk of preterm birth. CONCLUSION: Among index preterm pregnancies, high-grade chronic placental inflammation was associated with recurrent preterm birth. Low-grade maternal vascular malperfusion was associated with recurrent preterm birth only among those with an early or moderate index preterm birth (<34 weeks of gestation). These findings may be useful in determining the risk profile for individual patients and may generate hypotheses as to the pathogenesis of recurrent preterm birth.

Elevated Glucose Challenge Test in a Nondiabetic Index Pregnancy and Gestational Diabetes in a Subsequent Pregnancy.

OBJECTIVE: The aim of this study was to evaluate whether a 1-hour glucose challenge test (GCT) ≥140 mg/dL in a nondiabetic index pregnancy is associated with the development of gestational diabetes mellitus (GDM) in a subsequent pregnancy. STUDY DESIGN: We performed a retrospective cohort study from a single institution from June 2009 to December 2018. Women with a nondiabetic index singleton gestation who underwent a 1-hour GCT at 24 to 28 weeks and had a successive singleton delivery were included. GDM was defined by a 1-hour GCT of ≥ 200 mg/dL, ≥2 of 4 elevated values on a 3-hour GCT, or a diagnosis of GDM defined by International Classification of Disease codes in the electronic medical record. Univariable analyses were performed to evaluate the associations between an elevated 1-hour GCT result in the index pregnancy, maternal characteristics, and the development of GDM in the subsequent pregnancy. Variables found to be significant (p < 0.05) were included in multivariable analysis. RESULTS: A total of 2,423 women were included. Of these, 340 (14.0%) had an elevated 1-hour GCT in the index pregnancy. Women with an elevated 1-hour GCT in the index pregnancy compared with those without were significantly more likely to be older, married, privately insured, of Hispanic ethnicity or Asian race, chronically hypertensive, have a higher body mass index (BMI), have a shorter inter-pregnancy interval, and to develop GDM in the subsequent pregnancy (14.4 vs. 3.3%, p < 0.001). In multivariable analysis, an elevated 1-hour GCT (adjusted odds ratio [aOR]: 4.54, 95% confidence interval [CI]: 3.02-6.81), first-trimester BMI ≥30 kg/m2 in the index pregnancy (aOR: 3.10, 95% CI: 2.03-4.71), Asian race (aOR: 2.96, 95% CI: 1.70-5.12), Hispanic ethnicity (aOR: 2.11, 95% CI: 1.12-4.00), and increasing age (aOR: 1.07, 95% CI: 1.02-1.12) were significantly associated with an increased risk of GDM in the subsequent pregnancy. CONCLUSION: An elevated 1-hour GCT in a nondiabetic index pregnancy is associated with a fourfold increased risk of GDM in a subsequent pregnancy. KEY POINTS: · An abnormal 1 hour GCT in an index pregnancy is associated with GDM in a subsequent pregnancy.. · An abnormal 1 hour GCT may be an independent risk factor for GDM in a subsequent pregnancy.. · An abnormal 1 hour GCT is associated with a 4 fold increased risk of GDM in a subsequent pregnancy..

A Multifaceted Surgical Site Infection Prevention Bundle for Cesarean Delivery.

OBJECTIVE: Surgical site infections (SSI, including wound infections, endometritis, pelvic abscess, and sepsis) may complicate cesarean section (C/S). We report outcomes before and after the introduction of an SSI prevention bundle that did not include antibiotics beyond routine prophylaxis (cefazolin, or gentamicin/clindamycin for penicillin-allergic patients). STUDY DESIGN: The prevention bundle was introduced following an increase in C/S-associated SSI, which itself was associated with an institutional switch in preoperative scrub from povidone-iodine to chlorhexidine gluconate (CHG)/isopropanol. Components of the bundle included: (1) full-body preoperative wash with 4% CHG cloths; (2) retraining on surgeon hand scrub; (3) retraining for surgical prep; and (4) patient education regarding wound care. Patients delivered by C/S at ≥24 weeks of gestation were segregated into four epochs over 7 years: (1) baseline (18 months when povidone-iodine was used); (2) CHG scrub (18 months after skin prep was switched to CHG); (3) bundle implementation (24 months); and (4) maintenance (24 months following implementation). RESULTS: A total of 3,637 patients were included (n = 667, 796, 1098, and 1076, respectively, in epochs 1-4). A rise in SSI occurred with the institutional switch from povidone-iodine to CHG (i.e., from baseline to the CHG scrub epoch, 8.4-13.3%, p < 0.01). Following the intervention (maintenance epoch), this rate decreased to below baseline values (to 4.5%, p < 0.01), attributable to a decline in wound infection (rates in the above three epochs 6.9, 12.9, and 3.5%, respectively, p < 0.01), with no change in endometritis. In multivariable analysis, only epoch and body mass index (BMI) were independently associated with SSI. The improvement associated with the prevention bundle held for stratified analysis of specific risk factors such as chorioamnionitis, prior C/S, obesity, labor induction, and diabetes. CONCLUSION: Implementation of a prevention bundle was associated with a reduction in post-C/S SSI. This improvement was achieved without the use of antibiotics beyond standard preoperative dosing.

Horses and zebras: probabilities, uncertainty, and cognitive bias in clinical diagnosis.

Medical diagnosis is typically an iterative process guided by integration and synthesis of data into a model of disease. However, facts are not the only inputs into this process. A case of medical mis-diagnosis is presented, in which systematic cognitive bias is considered to have played a role in generating error. Specific cognitive biases are cited, and measures that can be taken to minimize their negative impact are reviewed.

Surfactant protein A suppresses preterm delivery induced by live Escherichia coli in mice.

Preterm birth accounts for the majority of neonatal morbidity and mortality in the developed world. A significant proportion of cases of spontaneous preterm labor are attributable to infections within gestational tissues. Surfactant protein A (SP-A), a collectin produced in the fetal lung and other tissues, has been shown previously in mice to suppress preterm delivery due to intrauterine (IU) instillation of sterile proinflammatory substances. Here we report a powerful antilabor effect for SP-A after IU infection with live Escherichia coli. SP-A abolished preterm birth (rate reduced from 100% to 0%) when it was administered into the uterus simultaneously with bacterial infection, reducing it by 75% when administered intravenously at the same time as IU bacterial inoculation, and by 48% when administered intravenously 4 h after IU bacterial infection. This effect on preterm delivery was accompanied by a parallel benefit on fetal survival in utero. SP-A had no effect on bacterial growth but reversed several major consequences of infection, including increased production of inflammatory mediators and a shift in macrophage polarization to the M1 phenotype. These findings suggest that exogenous SP-A has potential use to counteract infection-induced labor by reversing its proinflammatory consequences.

Interleukin 22 prevents lipopolysaccharide- induced preterm labor in mice.

Preterm birth is widespread and causes 35% of all neonatal deaths. Infants who survive face potential long-term complications. A major contributing factor of preterm birth is infection. We investigated the role of interleukin 22 (IL22) as a potential clinically relevant cytokine during gestational infection. IL22 is an effector molecule secreted by immune cells. While the expression of IL22 was reported in normal nonpregnant endometrium and early pregnancy decidua, little is known about uterine IL22 expression during mid or late gestational stages of pregnancy. Since IL22 has been shown to be an essential mediator in epithelial regeneration and wound repair, we investigated the potential role of IL22 during defense against an inflammatory response at the maternal-fetal interface. We used a well-established model to study infection and infection-associated inflammation during preterm birth in the mouse. We have shown that IL22 is upregulated to respond to an intrauterine lipopolysaccharide administration and plays an important role in controlling the risk of inflammation-induced preterm birth. This paper proposes IL22 as a treatment method to combat infection and prevent preterm birth in susceptible patients.

Maternal and fetal roles in bacterially induced preterm labor in the mouse.

BACKGROUND: The relative roles of the mother and fetus in signaling for labor remain poorly understood. OBJECTIVE: We previously demonstrated using gene knockout (KO) mice that Escherichia coli-induced preterm delivery is completely dependent on MyD88, a toll-like receptor adaptor protein. Here we leveraged this finding to conduct a genetic experiment testing whether the mother, the fetus, or both signal for parturition in bacterially induced labor. STUDY DESIGN: Six different maternal/fetal genotype combinations for MyD88 were studied: wild-type (WT) dams carrying one of the following: (1) WT or (2) MyD88 heterozygous (het) fetuses (generated by mating WT females with WT or MyD88-knockout [KO] males, respectively); (3) WT dams carrying MyD88-KO fetuses (generated by replacing the ovaries of WT females with MyD88-KO ovaries, followed by mating with MyD88-KO males); a similar strategy was used to generate MyD88-KO dams carrying (4) MyD88-KO, (5) MyD88 het, or (6) WT fetuses. On day 14.5 of gestation, mice received intrauterine injections of either 1 × 10(9) killed E coli or sterile medium. Delivery of ≥ 1 fetus within 48 hours was considered preterm. A separate group of similarly treated pregnant mice was euthanized 5 hours after surgery for gene expression and tissue analysis. RESULTS: E coli-induced preterm delivery is dependent on maternal and not fetal genotype: > 95% of WT and < 5% of MyD88-KO dams deliver prematurely, regardless of fetal genotype (P = .0001). In contrast, fetal survival in utero is influenced by fetal genotype: in MyD88-KO dams, in which premature birth rarely occurs, only 81% of WT and 86% of MyD88-heterozygous fetuses were alive 48 hours after surgery compared with 100% of MyD88-KO fetuses (P < .01). Messenger ribonucleic acids for the inflammatory mediators interleukin-1ß, tumor necrosis factor, interleukin-6, and cyclooxygenase-2 were elevated in uterine tissues only in WT mothers treated with E coli and were low or undetectable in the uteri of KO mothers or in animals treated with saline. Serum progesterone levels were lower in KO mothers with WT ovaries than in WT mothers with KO ovaries, but bacterial exposure did not have an impact on these levels. CONCLUSION: In the murine E coli-induced labor model, preterm delivery and uterine expression of inflammatory mediators is determined by the mother and not the fetus and is not attributable to a decline in serum progesterone.

Efficiency of Screening for the Recurrence of Antenatal Group B Streptococcus Colonization in a Subsequent Pregnancy: A Systematic Review and Meta-analysis with Independent Patient Data.

OBJECTIVE: The objective of this study was to evaluate the risk of recurrent group B streptococcus (GBS) colonization in a subsequent pregnancy and to assess clinical characteristics that influence this risk. STUDY DESIGN: A systematic review and meta-analysis was performed. Databases were searched from inception through June 2015 using PubMed, Embase, Scopus, Central, and ClinicalTrials.gov. Studies were eligible if they assessed antenatal GBS colonization in two successive pregnancies. The quality of included studies was evaluated. Independent patient data was requested from the authors of the included trials. Unadjusted odds ratios (OR) were pooled using the Mantel-Haenszel fixed effect model. RESULTS: In the five studies identified, two studies lacked a nonexposed cohort. GBS colonization in the index pregnancy was associated with a higher risk of recurrence of GBS colonization in a subsequent pregnancy (three studies: 50.2 compared with 14.1%; pooled fixed effects OR, 6.05; 95% confidence interval [CI], 4.84-7.55). When heavy colonization with GBS was compared with colonization by vaginal culture only, an increased risk of recurrence was shown (four studies: 52.0 compared with 45.1%, pooled fixed effects OR, 1.54; 95% CI, 1.02-2.31). CONCLUSION: Women colonized with GBS are at significantly higher odds for recurrent colonization in a subsequent pregnancy when compared with women who were not colonized in an index pregnancy. If the individual is considered heavily colonized with GBS, there appears to be an association with an increased risk compared with conventional culture. Subgroup analysis of the variables time interval ≤ 12 months between subsequent pregnancies, body mass index ≥ 30 kg/m(2), race, ethnicity, and primiparous in the subsequent pregnancy showed no effect.

Depletion of polymorphonuclear leukocytes has no effect on preterm delivery in a mouse model of Escherichia coli-induced labor.

OBJECTIVE: The objective of the study was to investigate the role of polymorphonuclear leukocytes (PMNs) in a mouse model of Escherichia coli-induced labor. STUDY DESIGN: Intraperitoneal injection of rabbit antimouse PMN antiserum or control was performed in CD-1 mice 29 hours and 5 hours prior to laparotomy and intrauterine injection of either killed E coli or phosphate-buffered saline on day 14.5 of pregnancy. Preterm delivery was defined as delivery of at least 1 pup within 48 hours. Circulating leukocyte counts were determined manually or by flow cytometry at the time of surgery and 8, 24, and 48 hours afterward. Maternal and fetal tissues were analyzed in a separate group of animals 8 hours after surgery. RESULTS: Pretreatment with anti-PMN antiserum significantly decreased the numbers of circulating leukocytes and the proportion of neutrophils among all leukocytes by 70-80% at surgery and at least 8 hours thereafter. Neutrophil depletion significantly reduced 2 markers of neutrophil activation in the uterus and placenta (neutrophil elastase and myeloperoxidase activity) and neutrophil infiltration into gestational tissues in bacterially treated animals to baseline (control) levels but did not affect preterm birth rates. The large E coli-induced increases in uterine inflammatory markers (interleukin-1ß, tumor necrosis factor, chemokine ligand-5, cyclooxygenase-2) were not affected or were only minimally affected by neutrophil depletion. CONCLUSION: Although PMN antiserum reduces both neutrophil number and activity, it does not diminish sensitivity to bacterially induced delivery or meaningfully alter the expression of inflammatory markers in the mouse model. Preterm birth and inflammation in this model are not likely to depend on neutrophil function.

Regulation of apoptosis and innate immune stimuli in inflammation-induced preterm labor.

An innate immune response is required for successful implantation and placentation. This is regulated, in part, by the a2 isoform of V-ATPase (a2V) and the concurrent infiltration of M1 (inflammatory) and M2 (anti-inflammatory) macrophages to the uterus and placenta. The objective of the present study was to identify the role of a2V during inflammation-induced preterm labor in mice and its relationship to the regulation of apoptosis and innate immune responses. Using a mouse model of infection-induced preterm delivery, gestational tissues were collected 8 h after intrauterine inoculation on day 14.5 of pregnancy with either saline or peptidoglycan (PGN; a TLR 2 agonist) and polyinosinic-polycytidylic acid [poly(I:C); a TLR3 agonist], modeling Gram-positive bacterial and viral infections, respectively. Expression of a2V decreased significantly in the placenta, uterus, and fetal membranes during PGN+poly(I:C)-induced preterm labor. Expression of inducible NO synthase was significantly upregulated in PGN+poly(I:C)-treated placenta and uterus. PGN+poly(I:C) treatment disturbed adherens junction proteins and increased apoptotic cell death via an extrinsic pathway of apoptosis among uterine decidual cells and spongiotrophoblasts. F4/80(+) macrophages were increased and polarization was skewed in PGN+poly(I:C)-treated uterus toward double-positive CD11c(+) (M1) and CD206(+) (M2) cells, which are critical for the clearance of dying cells and rapid resolution of inflammation. Expression of Nlrp3 and activation of caspase-1 were increased in PGN+poly(I:C)-treated uterus, which could induce pyroptosis. These results suggest that the double hit of PGN+poly(I:C) induces preterm labor via reduction of a2V expression and simultaneous activation of apoptosis and inflammatory processes.

Platelet-activating factor: a role in preterm delivery and an essential interaction with Toll-like receptor signaling in mice.

Platelet-activating factor (PAF), a potent phospholipid activator of inflammation that signals through its cognate receptor (platelet-activating factor receptor, PTAFR), has been shown to induce preterm delivery in mice. Toll-like receptors (TLRs) are transmembrane receptors that mediate innate immunity. We have shown previously that Escherichia coli-induced preterm delivery in mice requires TLR signaling via the adaptor protein myeloid differentiation primary response gene 88 (MyD88), but not an alternative adaptor, Toll/IL-1 receptor domain-containing adapter protein-inducing interferon-beta (TRIF). In the present work, we analyzed the role of endogenously produced PAF in labor using mice lacking (knockout [KO]) PAF acetylhydrolase (PAF-AH; the key degrading enzyme for PAF). PAF-AH KO mice are more susceptible to E. coli-induced preterm delivery and inflammation than controls. In peritoneal macrophages, the PTAFR agonist carbamyl PAF induces production of inflammatory markers previously demonstrated to be upregulated during bacterially induced labor, including: inducible nitric oxide synthase (Nos2), the chemokine Ccl5 (RANTES), tumor necrosis factor (Tnf), and level of their end-products (NO, CCL5, TNF) in a process dependent upon both IkappaB kinase and calcium/calmodulin-dependent protein kinase II. Interestingly, this induced expression was completely eliminated not only in macrophages deficient in PTAFR, but also in those lacking either TLR4, MyD88, or TRIF. The dependence of PAF effects upon TLR pathways appears to be related to production of PTAFR itself: PAF-induced expression of Ptafr mRNA was eliminated completely in TLR4 KO and partially in MyD88 and TRIF KO macrophages. We conclude that PAF signaling plays an important role in bacterially induced preterm delivery. Furthermore, in addition to its cognate receptor, PAF signaling in peritoneal macrophages requires TLR4, MyD88, and TRIF.

Impact of toll-like receptor 4 deficiency on the response to uterine ischemia/reperfusion in mice.

Our objective was to determine the role of toll-like receptor 4 (TLR4) in uterine ischemia/reperfusion (I/R)-induced fetal growth restriction (FGR). Pregnant TLR4-deficient and wild-type mice were subjected to I/R or a sham procedure. Fetal and placental weights were recorded and tissues were collected. Pep-1 (inhibits low-molecular-weight hyaluronan (LMW-HA) binding to TLR4) was used to determine whether LMW-HA-TLR4 interaction has a role in FGR. TLR4-deficient mice exhibited significantly lower baseline fetal weights compared with wild-type mice (P<0.05), along with extensive placental calcification that was not present in wild-type mice. Following I/R, fetal and placental weights were significantly reduced in wild-type (P<0.05) but not in TLR4-deficient mice. However, I/R increased fetal loss (P<0.05) only in TLR4-deficient mice. Corresponding with the reduced fetal weights, uterine myeloperoxidase activity increased in wild-type mice (P<0.001), indicating an inflammatory response, which was absent in TLR4-deficient mice. TLR4 was shown to have a regulatory role for two anti-inflammatory cytokines: interferon-B1 decreased only in wild-type mice (P<0.01) and interleukin-10 increased only in TLR4-deficient mice (P<0.001), in response to I/R. Pep-1 completely prevented I/R-induced FGR (P<0.001), indicating a potential role for the endogenous TLR4 ligand LMW-HA in I/R-induced FGR. In conclusion, uterine I/R in pregnancy produces FGR that is dependent on TLR4 and endogenous ligand(s), including breakdown products of HA. In addition, TLR4 may play a role in preventing pregnancy loss after uterine I/R.