Tranexamic acid, as an adjunct to oxytocin prophylaxis, in the prevention of postpartum haemorrhage in women undergoing elective caesarean section: A single-centre double-blind randomised controlled trial.

OBJECTIVE: To evaluate the effectiveness of tranexamic acid (TXA) in reducing blood loss during elective caesarean sections in women with and without risk factors for postpartum haemorrhage (PPH). DESIGN: A double-blind, randomised placebo-controlled trial. SETTING: An academic tertiary referral centre in Singapore. POPULATION: Multiethnic women aged 21 years or older undergoing elective caesarean section. METHODS: Randomisation to intravenous TXA or normal saline (placebo) 10 minutes before skin incision. MAIN OUTCOME MEASURES: Calculated estimated blood loss (cEBL), derived from blood volume and haematocrit levels. RESULTS: Between June 2020 and October 2021, 200 women were randomised to the placebo or TXA groups. Women who received prophylactic TXA had a significantly lower mean cEBL compared with those receiving placebo (adjusted mean difference -126.4 mL, 95% CI -243.7 to -9.1, p = 0.035). The effect was greatest in those at high risk for PPH, with a reduction in cEBL (mean difference -279.6 mL, 95% CI -454.8 to -104.3, p = 0.002) and a lower risk of cEBL ≥500 mL (risk ratio [RR] 0.54, 95% CI 0.36-0.83, p = 0.007) and cEBL ≥1000 mL (RR 0.44, 95% CI 0.20-0.98, p = 0.016). Subgroup analysis showed benefit for women with preoperative haemoglobin <10.5 g/dL (mean difference -281.9 mL, 95% CI -515.0 to -48.8, p = 0.019). There was no significant difference in need for additional medical or surgical interventions. There were no maternal or neonatal adverse outcomes. CONCLUSION: Prophylactic TXA should be considered in women with risk factors for PPH, and those most likely to benefit are those with preoperative haemoglobin <10.5 g/dL.

Peritoneal autoantibody profiling identifies p53 as an autoantibody target in endometriosis.

OBJECTIVE: To map the peritoneal autoantibody (AAb) landscape in women with endometriosis. DESIGN: Case-control laboratory study. SETTING: Academic medical and research units. PATIENT(S): Women who presented with or without endometriosis. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Using native-conformation and citrullinated modified protein arrays, proteome-wide analysis of AAbs against 1,623 proteins were profiled in peritoneal fluids (PFs) of 25 women with endometriosis and 25 women without endometriosis. RESULT(S): In women with endometriosis, the median number of AAbs detected was 4, including AAbs that targeted autoantigens involved in implantation, B-cell activation/development, and aberrant migration and mitogenicity. Forty-six percent of women with endometriosis have ≥5 peritoneal AAbs. Conversely, in women without endometriosis, the median number of detected AAbs was 1. Autoantibodies recognizing tumor suppressor protein p53 were the most commonly detected AAbs, being present in 35% of women with endometriosis, and p53 AAb was associated with a monocyte/macrophage-like PF cytokine signature. Further investigation of the global reactivity of AAbs against citrullinated PF antigens by peptidylarginine deiminase enzymes 1, 2, and 6 revealed anticitrullinated p53 as the only AAb target elevated and citrullinated by all 3 peptidylarginine deiminase isotypes. Furthermore, unsupervised hierarchical clustering and integrative pathway analysis revealed that 60% of women with endometriosis-associated infertility were positive for AAbs, which are involved in platelet-derived growth factor, transforming growth factor-ß, RAC1/PAK1/p38/MMP2 signaling, LAT2/NTAL/LAB-mediated calcium mobilization, and integrin-mediated cell adhesion. CONCLUSION(S): Together, our data identify peritoneal autoimmunity in a significant subset of women with endometriosis, with implications on infertility and disease pathophysiology. In these patients, p53 was identified as the most frequent PF AAb target, which was present in both the native and citrullinated forms.

Modifiable Risk Factor Score and Fecundability in a Preconception Cohort in Singapore.

Importance: Although multiple modifiable risk factors have been identified for reduced fecundability (defined as lower probability of conception within a menstrual cycle), no scoring system has been established to systematically evaluate fecundability among females who are attempting to conceive. Objective: To examine the association of a risk score based on 6 modifiable factors with fecundability, and to estimate the percentage reduction in incidence of nonconception if all study participants achieved a minimal risk score level. Design, Setting, and Participants: This population-based cohort study obtained data from the S-PRESTO (Singapore Preconception Study of Long-Term Maternal and Child Outcomes) prospective cohort study. Females of reproductive age who were trying to conceive were enrolled from February 2015 to October 2017 and followed for 1 year, ending in November 2018. Data were analyzed from March to May 2022. Exposures: A reduced fecundability risk score was derived by giving participants 1 point for each of the following factors: unhealthy body mass index, unhealthy diet, smoking, alcohol intake, folic acid supplement nonuser, and older maternal age. Total scores ranged from 0 to 6 and were classified into 5 levels: level 1 (score of 0 or 1), level 2 (score of 2), level 3 (score of 3), level 4 (score of 4), and level 5 (score of 5 or 6). Main Outcomes and Measures: Fecundability, measured by time to conception in cycles, was analyzed using discrete-time proportional hazards models with confounder adjustment. Results: A total of 937 females (mean [SD] age, 30.8 [3.8] years) were included, among whom 401 (42.8%) spontaneously conceived within 1 year of attempting conception; the median (IQR) number of cycles before conception was 4 (2-7). Compared with participants with a level 1 risk score, those with level 2, 3, 4, and 5 risk scores had reductions in fecundability of 31% (adjusted fecundability ratio [FR], 0.69; 95% CI, 0.54-0.88), 41% (FR, 0.59; 95% CI, 0.45-0.78), 54% (FR, 0.46; 95% CI, 0.31-0.69) and 77% (FR, 0.23; 95% CI, 0.07-0.73), respectively. Assessment of the population attributable fraction showed that all participants achieving a minimal (level 1) risk level would be associated with a reduction of 34% (95% CI, 30%-39%) in nonconception within a year. Conclusions and Relevance: Results of this study revealed the co-occurrence of multiple modifiable risk factors for lowered fecundability and a substantially higher conception rate among participants with no or minimal risk factors. The risk assessment scoring system proposed is a simple and potentially useful public health tool for mitigating risks and guiding those who are trying to conceive.

Defects in protective cytokine profiles in spontaneous miscarriage in the first trimester.

OBJECTIVE: To study differences in cytokine expression profiles between women with ongoing pregnancy and those experiencing spontaneous miscarriage, among women who presented with threatened miscarriage before week 16 of gestation. DESIGN: Prospective cohort study. SETTING: Academic hospital. PATIENT(S): In this prospective cohort study, 155 pregnant women, comprising normal pregnant women recruited from antenatal clinics (n = 97) and women with threatened miscarriage recruited from an emergency walk-in clinic (n = 58). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Sixty-five serum cytokines quantified using multiplex immunoassay correlated with miscarriage outcomes. RESULT(S): Among women presenting with threatened miscarriage, those who eventually miscarried had significantly lower levels of interleukin (IL)-2, IL-12p70, IL-17A, B-cell-activating factor, B lymphocyte chemoattractant, basic nerve growth factor, interferon-γ, tumor necrosis factor-related apoptosis-inducing ligand, thymic stromal lymphopoietin, and tumor necrosis factor-α and higher levels of vascular endothelial growth factor A, IL-21, and stromal cell-derived factor 1α than those with ongoing pregnancy. Comparisons between normal pregnancies and women with threatened miscarriage who eventually miscarried revealed significant differences across 7 cytokines: B-cell-activating factor; B lymphocyte chemoattractant; basic nerve growth factor; IL-17A; fractalkine/CX3CL1; vascular endothelial growth factor A; and CCL22. Vascular endothelial growth factor A exhibited a negative correlation with the progesterone level (r = -0.270). The cluster of significant cytokines alludes to T cell proliferation, B-cell proliferation, natural killer cell-mediated cytotoxicity, and apoptosis as important pathways that determine pregnancy outcomes. Bioinformatic analysis further revealed alteration of the suppressor of cytokine signaling proteins family of Janus kinase-signal transducer and activator of transcription signaling axis by cytokines as a plausible key molecular mechanism in spontaneous miscarriage. CONCLUSION(S): This study demonstrates that the regulated balance between the proinflammatory and anti-inflammatory pathways is crucial to maintaining pregnancy. A better understanding of the cytokines associated with immunomodulatory effects may lead to novel targets for the prediction and treatment of spontaneous miscarriage.

Decreased Innate Migration of Pro-Inflammatory M1 Macrophages through the Mesothelial Membrane Is Affected by Ceramide Kinase and Ceramide 1-P.

The retrograde flow of endometrial tissues deposited into the peritoneal cavity occurs in women during menstruation. Classically (M1) or alternatively (M2) activated macrophages partake in the removal of regurgitated menstrual tissue. The failure of macrophage egress from the peritoneal cavity through the mesothelium leads to chronic inflammation in endometriosis. To study the migration differences of macrophage phenotypes across mesothelial cells, an in vitro model of macrophage egress across a peritoneal mesothelial cell monolayer membrane was developed. M1 macrophages were more sessile, emigrating 2.9-fold less than M2 macrophages. The M1 macrophages displayed a pro-inflammatory cytokine signature, including IL-1α, IL-1ß, TNF-α, TNF-ß, and IL-12p70. Mass spectrometry sphingolipidomics revealed decreased levels of ceramide-1-phosphate (C1P), an inducer of migration in M1 macrophages, which correlated with its poor migration behavior. C1P is generated by ceramide kinase (CERK) from ceramide, and blocking C1P synthesis via the action of NVP231, a specific CERK chemical inhibitor, prohibited the emigration of M1 and M2 macrophages up to 6.7-fold. Incubation with exogenously added C1P rescued this effect. These results suggest that M1 macrophages are less mobile and have higher retention in the peritoneum due to lower C1P levels, which contributes to an altered peritoneal environment in endometriosis by generating a predominant pro-inflammatory cytokine environment.

Development and Validation of a Lifestyle Behavior Tool in Overweight and Obese Women through Qualitative and Quantitative Approaches.

There is a paucity of effective intervention tools for overweight/obese women to assess, guide and monitor their eating behavior. This study aimed to develop a lifestyle intervention tool, assess its acceptability and usefulness, and verify its construct validity in overweight/obese women. The 6P tool (Portion, Proportion, Pleasure, Phase, Physicality, Psychology) was developed and 15 women with a body mass index (BMI) ≥ 25 kg/m2 were interviewed to assess its perceived acceptability and usefulness. Subsequently, the revised 6P tool was tested in 46 women with a BMI ≥ 25 kg/m2. The Three-Factor Eating Questionnaire (TFEQ), International Physical Activity Questionnaire-Short (IPAQ), and weight were measured at baseline and one-month. Most participants were satisfied with the presentation of the 6P tool (86.8%), and agreed it was useful in guiding healthy eating (81.6%) and raising awareness of eating behavior (97.4%). There were significant improvements in cognitive restraint (p = 0.010) and disinhibition (p = 0.030) (TFEQ), portion size (P1), pleasure behaviors (P3), and total composite 6P score (p < 0.001). However, there was no significant reduction in weight or increase in physical activity. The 6P tool is acceptable and presents with good validity for assessing lifestyle behaviors.

Risk score to stratify miscarriage risk levels in preconception women.

Spontaneous miscarriage is one of the most common complications of pregnancy. Even though some risk factors are well documented, there is a paucity of risk scoring tools during preconception. In the S-PRESTO cohort study, Asian women attempting to conceive, aged 18-45 years, were recruited. Multivariable logistic regression model coefficients were used to determine risk estimates for age, ethnicity, history of pregnancy loss, body mass index, smoking status, alcohol intake and dietary supplement intake; from these we derived a risk score ranging from 0 to 17. Miscarriage before 16 weeks of gestation, determined clinically or via ultrasound. Among 465 included women, 59 had miscarriages and 406 had pregnancy ≥ 16 weeks of gestation. Higher rates of miscarriage were observed at higher risk scores (5.3% at score ≤ 3, 17.0% at score 4-6, 40.0% at score 7-8 and 46.2% at score ≥ 9). Women with scores ≤ 3 were defined as low-risk level (< 10% miscarriage); scores 4-6 as intermediate-risk level (10% to < 40% miscarriage); scores ≥ 7 as high-risk level (≥ 40% miscarriage). The risk score yielded an area under the receiver-operating-characteristic curve of 0.74 (95% confidence interval 0.67, 0.81; p < 0.001). This novel scoring tool allows women to self-evaluate their miscarriage risk level, which facilitates lifestyle changes to optimize modifiable risk factors in the preconception period and reduces risk of spontaneous miscarriage.

Gestational age-specific normative values and determinants of serum progesterone through the first trimester of pregnancy.

Progesterone is a steroid hormone that is critical for implantation and maintenance of pregnancy, and low levels are associated with higher miscarriage risk. However, little is known about its trajectory during early pregnancy. We sought to determine the gestational age-specific normative values of serum progesterone on a week-by-week basis, and its associated maternal and fetal factors, during the first trimester of a viable low-risk pregnancy. A cross-sectional study was conducted at KK Women's and Children's Hospital from 2013 to 2018. 590 women with a single viable intrauterine low-risk pregnancy, between gestational weeks 5 and 12, were recruited. Serum progesterone showed an increasing trend during the first trimester, with a transient decline between gestational weeks 6-8, corresponding to the luteal-placental shift. Lowest levels were seen at week 7. Maternal age, BMI, parity, gestational age and outcome of pregnancy at 16 weeks' gestation were found to be associated with progesterone levels. Normative values of serum progesterone for low-risk pregnancies would form the basis for future work on pathological levels of serum progesterone that may increase risk of miscarriage. Larger studies are required to validate these normative values, and personalize them to account for maternal age, BMI, parity and gestational age.

DORSCON Orange: An Approach to Challenges in a Busy Antenatal Diagnostic Centre in the Midst of a Global Pandemic.

The WHO declared the coronavirus disease 2019 (COVID-19) a global pandemic on 11 March 2020. Lessons from SARS epidemic led Singapore to develop stringent infection control protocols in preparation for future pandemics. However, unlike SARS, COVID-19 appears to be more transmissible and is predicted to continue for longer. As of 14 June 2020, there have been 40,197 positive cases with 26 deaths in Singapore, and KK Women's and Children's Hospital (KKH) has managed a total of 73 cases. Obstetrics ultrasound is an indispensable medical service and must continue to operate during a pandemic. A key balance must be struck between keeping patients and healthcare workers safe while being able to provide quality and prompt obstetric care. Our Antenatal Diagnostic Centre (ADC) in KKH developed new strategies to adapt to the pandemic when the national Disease Outbreak Response System Condition (DORSCON) was raised from yellow to orange on 7 February 2020. In this paper, we discuss our clinical workflow to reduce the risk of transmission amongst patients and staff while minimising disruption to our services.

Novel approach using serum progesterone as a triage to guide management of patients with threatened miscarriage: a prospective cohort study.

Threatened miscarriage is a common gynaecological emergency, with up to 25% of women eventually progressing to spontaneous miscarriage. The uncertainty of pregnancy outcomes results in significant anxiety. However, there is currently no acceptable framework for triaging patients presenting with threatened miscarriage. We aim to evaluate the efficacy and safety of a novel clinical protocol using a single serum progesterone level to prognosticate and guide management of patients with threatened miscarriage. 1087 women presenting with threatened miscarriage were enrolled in the study. The primary outcome was spontaneous miscarriage by 16 weeks' gestation. Among the 77.9% (847/1087) of study participants with serum progesterone ≥ 35 nmol/L who were not treated with oral dydrogesterone, the miscarriage rate was 9.6% (81/847). This did not differ significantly from the 8.5% (31/364) miscarriage rate observed in our prior studies; p = 0.566. Among women with serum progesterone < 35 nmol/L who were treated with dydrogesterone, the miscarriage rate was 70.8% (170/240). Our novel clinical triage protocol using a single serum progesterone level allowed both effective risk stratification and a reduction in progestogen use with no significant adverse pregnancy outcomes. This protocol, based on a single serum progesterone cutoff, can be readily adapted for use in other healthcare institutions.

Characterisation of serum progesterone and progesterone-induced blocking factor (PIBF) levels across trimesters in healthy pregnant women.

Progesterone-induced blocking factor (PIBF), which plays an important role in maintaining healthy pregnancies, has shown great promise as a prognostic biomarker for threatened miscarriage. To better characterise the physiological trends of progesterone and PIBF, we analysed serum progesterone and PIBF concentrations in healthy non-pregnant and pregnant women across trimesters. We saw increasing concentrations of progesterone and PIBF in pregnant women with advancing trimesters. The serum progesterone and PIBF percentiles across gestational age in healthy pregnancies can be used as a guide for the formulation of reference ranges. We also demonstrated a significant positive correlation between progesterone and PIBF levels. This study demonstrates increasing progesterone and PIBF concentrations in later trimesters and underscores the importance of progesterone and PIBF in healthy pregnancies. Characterisation of progesterone and PIBF across gestational age in healthy pregnant women may help to prognosticate pregnancy viability and support further research into the importance of progesterone and PIBF in the maintenance of healthy pregnancies.

Serum progesterone distribution in normal pregnancies compared to pregnancies complicated by threatened miscarriage from 5 to 13 weeks gestation: a prospective cohort study.

BACKGROUND: Progesterone is a critical hormone in early pregnancy. A low level of serum progesterone is associated with threatened miscarriage. We aim to establish the distribution of maternal serum progesterone in normal pregnancies compared to pregnancies complicated by threatened miscarriage from 5 to 13 weeks gestation. METHODS: This is a single centre, prospective cohort study of 929 patients. Women from the Normal Pregnancy [NP] cohort were recruited from antenatal clinics, and those in the Threatened Miscarriage [TM] cohort were recruited from emergency walk-in clinics. Women with multiple gestations, missed, incomplete or inevitable miscarriage were excluded from the study. Quantile regression was used to characterize serum progesterone levels in the NP and TM cohorts by estimating the 10th, 50th and 90th percentiles from 5 to 13 weeks gestation. Pregnancy outcome was determined at 16 weeks of gestation. Subgroup analysis within the TM group compared progesterone levels of women who subsequently miscarried with those who had ongoing pregnancies at 16 weeks of gestation. RESULTS: Median serum progesterone concentration demonstrated a linearly increasing trend from 57.5 nmol/L to 80.8 nmol/L from 5 to 13 weeks gestation in the NP cohort. In the TM cohort, median serum progesterone concentration increased from 41.7 nmol/L to 78.1 nmol/L. However, median progesterone levels were uniformly lower in the TM cohort by approximately 10 nmol/L at every gestation week. In the subgroup analysis, median serum progesterone concentration in women with ongoing pregnancy at 16 weeks gestation demonstrated a linearly increasing trend from 5 to 13 weeks gestation. There was a marginal and non-significant increase in serum progesterone from 19.0 to 30.3 nmol/L from 5 to 13 weeks gestation in women who eventually had a spontaneous miscarriage. CONCLUSIONS: Serum progesterone concentration increased linearly with gestational age from 5 to 13 weeks in women with normal pregnancies. Women with spontaneous miscarriage showed a marginal and non-significant increase in serum progesterone. This study highlights the pivotal role of progesterone in supporting an early pregnancy, with lower serum progesterone associated with threatened miscarriage and a subsequent complete miscarriage at 16 weeks gestation.

The randomised controlled trial of micronised progesterone and dydrogesterone (TRoMaD) for threatened miscarriage.

There has not been conclusive evidence in literature on the efficacy of progestogen in the treatment of threatened miscarriage, although some studies showed benefits. In our centre, threatened miscarriage is treated with either micronised progesterone (MP) or dydrogesterone (DYD). OBJECTIVE: The aim of this study is to compare clinical outcomes of miscarriage, extent of vaginal bleeding at follow-up and side effects between treatment groups. STUDY DESIGN: This study was a prospective parallel-group, open-label, randomized controlled trial. 141 women presenting with threatened miscarriage were randomised to either MP or DYD of which 118 were included in the analysis. Baseline maternal demographics and serum progesterone levels were collected at presentation. Post-treatment bleeding pattern and self-reported side effects were recorded at the follow-up visit (on day 4-10 of treatment). The occurrence of spontaneous miscarriage was ascertained at week 16 of gestation. RESULTS: The population with miscarriage and resolution of bleeding were not statistically different between MP and DYD groups. A significantly higher percentage of women treated with MP reported drowsiness (p = 0.003). After stratification into low and high serum progesterone levels, a significantly higher miscarriage rate was found in the low progesterone group, regardless of treatment type. CONCLUSION: In conclusion, extent of bleeding at day 4-10 and subsequent miscarriage rates were comparable between MP and DYD groups. However, fewer patients treated with DYD reported drowsiness and giddiness. The finding of significantly higher miscarriage rates in women with low progesterone levels despite treatment is an important factor to consider in counselling and prognosticating pregnancy outcomes.

Validation of serum progesterone <35nmol/L as a predictor of miscarriage among women with threatened miscarriage.

BACKGROUND: Our recent paper, based on a pilot cohort of 119 women, showed that serum progesterone <35 nmol/L was prognostic of spontaneous miscarriage by 16 weeks in women with threatened miscarriage in early pregnancy. Using a larger cohort of women from the same setting (validation cohort), we aim to assess the validity of serum progesterone <35 nmol/L with the outcome of spontaneous miscarriage by 16 weeks. METHODS: In a prospective cohort study, 360 pregnant women presenting with threatened miscarriage between gestation weeks 6-10 at a tertiary hospital emergency unit for women in Singapore were recruited for this study. The main outcome measure measured is spontaneous miscarriage prior to week 16 of gestation. Area under the ROC curve (AUC) and test characteristics (sensitivity, specificity, positive and negative predictive value) at a serum progesterone cutpoint of <35 nmol/L for predicting high and low risk of spontaneous miscarriage by 16 weeks were compared between the Pilot and Validation cohorts. RESULTS: Test characteristics and AUC values using serum progesterone <35 nmol/L in the validation cohort were not significantly different from those in the Pilot cohort, demonstrating excellent accuracy and reproducibility of the proposed serum progesterone cut-off level. CONCLUSIONS: The cut-off value for serum progesterone (35 nmol/L) demonstrated clinical relevance and allow clinicians to stratify patients into high and low risk groups for spontaneous miscarriage.

How can we better predict the risk of spontaneous miscarriage among women experiencing threatened miscarriage?

This study seeks to establish progesterone and progesterone-induced blocking factor (PIBF) levels as predictors of subsequent completed miscarriage among women presenting with threatened miscarriage between 6 and 10 weeks of gestation. Our secondary objective was to assess the known maternal risk factors, toward development of a parsimonious and clinician-friendly risk assessment model for predicting completed miscarriage. In this article, we present a prospective cohort study of 119 patients presenting with threatened miscarriage from gestation weeks 6 to 10 at a tertiary women's hospital emergency unit in Singapore. Thirty (25.2%) women had a spontaneous miscarriage. Low progesterone and PIBF levels are similarly predictive of subsequent completed miscarriage. Study results (OR, 95% CI) showed that higher levels of progesterone (0.91, 95% CI 0.88-0.94) and PIBF (0.99, 95% CI 0.98-0.99) were associated with lower risk of miscarriage. Low progesterone level was a very strong predictor of miscarriage risk in our study despite previous concerns about its pulsatile secretion. Low serum progesterone and PIBF levels predicted spontaneous miscarriage among women presenting with threatened miscarriage between gestation weeks 6 to 10. Predictive models to calculate probability of spontaneous miscarriage based on serum progesterone, together with maternal BMI and fetal heart are proposed.

Central primary primitive neuroectodermal tumor (cPNET) arising from an ovarian mature cystic teratoma in pregnancy: A case report and review of medical literature.

► This is a case of central PNET arising from a mature teratoma in the ovary in pregnancy. ► Fertility sparing surgery can be considered for early stage PNET of the ovary.

Regulation of epithelial-mesenchymal IL-1 signaling by PPARbeta/delta is essential for skin homeostasis and wound healing.

Skin morphogenesis, maintenance, and healing after wounding require complex epithelial-mesenchymal interactions. In this study, we show that for skin homeostasis, interleukin-1 (IL-1) produced by keratinocytes activates peroxisome proliferator-activated receptor beta/delta (PPARbeta/delta) expression in underlying fibroblasts, which in turn inhibits the mitotic activity of keratinocytes via inhibition of the IL-1 signaling pathway. In fact, PPARbeta/delta stimulates production of the secreted IL-1 receptor antagonist, which leads to an autocrine decrease in IL-1 signaling pathways and consequently decreases production of secreted mitogenic factors by the fibroblasts. This fibroblast PPARbeta/delta regulation of the IL-1 signaling is required for proper wound healing and can regulate tumor as well as normal human keratinocyte cell proliferation. Together, these findings provide evidence for a novel homeostatic control of keratinocyte proliferation and differentiation mediated via PPARbeta/delta regulation in dermal fibroblasts of IL-1 signaling. Given the ubiquitous expression of PPARbeta/delta, other epithelial-mesenchymal interactions may also be regulated in a similar manner.