Respiratory benefit in preterm lambs is progressively lost when the concentration of fetal plasma betamethasone is titrated below two nanograms per milliliter.

Antenatal steroid therapy is the standard of care for women at imminent risk of preterm delivery. Current dosing regimens use suprapharmacological doses to achieve extended fetal steroid exposures. We aimed to determine the lowest fetal plasma betamethasone concentration sufficient to achieve functional preterm lung maturation. Ewes with single fetuses underwent surgery to install a fetal jugular catheter. Adopting a stepwise design, ewes were randomized to either a saline-only group (negative control group; n = 9) or one of four betamethasone treatment groups. Each betamethasone group fetus received a fetal intravenous infusion to target a constant plasma betamethasone level of either 1) 2 ng/mL (2 ng/mL positive control group, n = 9); 2) 1 ng/mL, (1 ng/mL group, n = 10); 3) 0.5 ng/mL (0.5 ng/mL group, n = 10); or 4) 0.25 ng/mL (0.25 ng/mL group, n = 10). Fetuses were infused for 48 h, delivered, and ventilated. The positive control group, negative control group, and mid-point 0.5 ng/mL group animals were tested first. An interim analysis informed the final betamethasone group tested. Positive control group animals had large, statistically significant improvements in respiratory function. Based on an interim analysis, the 1.0 ng/mL group was studied in favor of the 0.25 ng/mL group. Treatment efficacy was progressively lost at plasma betamethasone concentrations lower than 2 ng/mL. We demonstrated that the acute respiratory benefit conveyed by antenatal steroid exposure in the fetal sheep is progressively lost when constant fetal plasma betamethasone concentrations are reduced below a targeted value of 2 ng/mL.NEW & NOTEWORTHY Lung maturation benefits in preterm lambs were progressively lost when fetal plasma betamethasone concentrations fell below 2 ng/mL. The effective floor threshold for a robust, lung-maturing exposure likely lies between 1 and 2 ng betamethasone per milliliter of plasma. Hypothalamic pituitary adrenal axis signaling and immunocyte populations remained materially disrupted at subtherapeutic steroid concentrations. These data demonstrate the potential to improve antenatal steroid therapy using reduced dose regimens informed by glucocorticoid pharmacokinetics and pharmacodynamics.

Intrauterine Candida albicans Infection Causes Systemic Fetal Candidiasis With Progressive Cardiac Dysfunction in a Sheep Model of Early Pregnancy.

INTRODUCTION: Several recent studies have identified a potential role for intrauterine Candida albicans in adverse pregnancy outcomes, including preterm birth. There is, however, a limited understanding of the impact of intrauterine candida infection on fetal well-being in early pregnancy. Using a sheep model of early pregnancy, the aims of this study were to determine (1) the ability of experimentally induced intrauterine C albicans to infect the fetus and (2) whether C albicans exposure in early pregnancy is associated with alterations in fetal cardiac function, as measured by spectral tissue Doppler imaging analysis of fetal cardiac function. METHODS: Merino ewes carrying singleton pregnancies at 89 days' gestation (term is ∼150 days) received C albicans (n = 8) via ultrasound-guided intra-amniotic injection. Saline-exposed fetuses served as controls (n = 6). Spectral tissue Doppler imaging echocardiography and amniotic fluid collection were performed at baseline and 24 and 72 hours after intrauterine C albicans injection. Fetal tissues were collected at postmortem for analysis of infection and inflammation. RESULTS: Relative to saline control, intrauterine C albicans infection resulted in pronounced increases in amniotic fluid tumor necrosis factor α (TNF-α; P < .05) and cytokine/chemokine messenger RNA (interleukin [IL] 1ß, IL-6, TNF-α, and monocyte chemoattractant protein 1; P < .05) in the fetal myocardium, lung, skin, and liver at 72 and 96 hours postinfection. Spectral tissue Doppler imaging showed diastolic dysfunction at 24 hours and severe biventricular diastolic dysfunction 72 hours postinfection. CONCLUSION: Intrauterine C albicans infection in a sheep model of early pregnancy causes systemic fetal candidiasis, which is associated with a robust systemic inflammatory response and progressive cardiac dysfunction detectable by spectral tissue Doppler imaging.

Preclinical evaluation of drugs to block inflammation-driven preterm birth.

Intrauterine inflammation, the major cause of early preterm birth, can have microbial and sterile aetiologies. We assessed in a Transwell model the anti-inflammatory efficacies of five drugs on human extraplacental membranes delivered after preterm spontaneous labour (30-34 wk). Drugs [TPCA1 (IKKß inhibitor), 5 z-7-oxozeaenol (OxZ, TAK1 inhibitor), inhibitor of NF-κB essential modulator binding domain (iNBD), SB239063 (p38 MAPK inhibitor) and N-acetyl cysteine (free radical scavenger free radicals)] were added after 12 h equilibration to the amniotic compartment. Concentrations of IL-6, TNF-α, MCP-1, IL-1ß and PGE2 in the media, and IL6, TNFA and PTGS2 mRNA expression levels in membranes, were determined after 12 h. Data were analysed using mixed models analyses. Thirteen of the 28 membranes had histological chorioamnionitis (HCA+); five were positive for bacterial culture and six for fetal inflammatory reaction. Baseline PGE2 and cytokine production was similar between HCA- and HCA+ membranes. Anti-inflammatory effects were also similar between HCA- and HCA+ membranes. TPCA1 and OxZ were the most effective drugs; each inhibited amniotic secretion of 4/5 pro-inflammatory mediators and mRNA levels of 2/3, regardless of stimulus. We conclude that treatment with TPCA1 or OxZ, in combination with antibiotics, may minimise the adverse effects of intrauterine inflammation in pregnancy.

Ureaplasma parvum genotype, combined vaginal colonisation with Candida albicans, and spontaneous preterm birth in an Australian cohort of pregnant women.

BACKGROUND: Detection of Ureaplasma, Mycoplasma and Candida spp. in the vagina during pregnancy has previously been associated with preterm birth (PTB). However, the prevalence of these microorganisms and the associated obstetric risks (likely to be population-specific) have not been determined in Australian women; furthermore, in the case of Ureaplasma spp., very few studies have attempted characterisation at the species level and none have examined genotype/serovar status to further refine risk assessment. METHODS: In order to address these issues we sampled the vaginal fluid of 191 pregnant Australian women at three time points in pregnancy. Culture methods were used for detection of Ureaplasma spp. and Candida spp., and real-time PCR was used for speciation of U. parvum and U. urealyticum, non-albicans Candida spp., Mycoplasma hominis and Mycoplasma genitalium. High-resolution melt PCR was used to genotype U. parvum. Data on various lifestyle factors (including sex during pregnancy and smoking), antimicrobial use and pregnancy outcome were collected on all participants. Chi-square tests were used to assess the association of vaginal microorganisms with PTB. RESULTS: Detection of Ureaplasma spp. was higher among spontaneous PTB cases, specifically in the presence of U. parvum [77 % preterm (95 % confidence interval (CI) 50-100 %) vs. 36 % term (CI: 29-43 %), p = 0.004], but not U. urealyticum. The association with PTB strengthened when U. parvum genotype SV6 was detected (54 % preterm (CI: 22-85 %) vs. 15 % term (CI: 10-20 %), p = 0.002); this genotype was also present in 80 % (4/5) of cases of PTB <34 weeks gestation. When present with Candida albicans in the same sample, the association with PTB remained strong for both U. parvum [46 % preterm (CI: 15-78 %) vs. 13 % term (CI: 8-18 %), p = 0.005] and U. parvum genotype SV6 [39 % preterm (CI: 8-69 %) vs. 7 % term (CI: 3-11 %), p = 0.003]. With the exception of Candida glabrata, vaginal colonisation status for all organisms was stable throughout pregnancy. Smoking significantly increased the likelihood of detection of all target organisms. CONCLUSIONS: These data suggest that the presence of different species and serovars of Ureaplasma spp. in the vagina confers an increased risk of spontaneous PTB, findings which may be useful in risk assessment for identifying women who would benefit from antimicrobial treatment.

Outside-in? Acute fetal systemic inflammation in very preterm chronically catheterized sheep fetuses is not driven by cells in the fetal blood.

BACKGROUND: The preterm birth syndrome (delivery before 37 weeks gestation) is a major contributor to the global burden of perinatal morbidity and death. The cause of preterm birth is complex, multifactorial, and likely dependent, at least in part, on the gestational age of the fetus. Intrauterine infection is frequent in preterm deliveries that occur at <32 weeks gestation; understanding how the fetus responds to proinflammatory insult will be an important step towards early preterm birth prevention. However, animal studies of infection and inflammation in prematurity commonly use older fetuses that possess comparatively mature immune systems. OBJECTIVE: Aiming to characterize acute fetal responses to microbial agonist at a clinically relevant gestation, we used 92-day-old fetuses (62% of term) to develop a chronically catheterized sheep model of very preterm pregnancy. We hypothesized that any acute fetal systemic inflammatory responses would be driven by signaling from the tissues exposed to Escherichia coli lipopolysaccharide that is introduced into the amniotic fluid. STUDY DESIGN: Eighteen ewes that were carrying a single fetus at 92 days of gestation had recovery surgery to place fetal tracheal, jugular, and intraamniotic catheters. Animals were recovered for 24 hours before being administered either intraamniotic E coli lipopolysaccharide (n = 9) or sterile saline solution (n = 9). Samples were collected for 48 hours before euthanasia and necroscopy. Fetal inflammatory responses were characterized by microarray analysis, quantitative polymerase chain reaction, and enzyme-linked immunosorbent assay. RESULTS: Intraamniotic lipopolysaccharide reached the distal trachea within 2 hours. Lipopolysaccharide increased tracheal fluid interleukin-8 within 2 hours and generated a robust inflammatory response that was characterized by interleukin-6 signaling pathway activation and up-regulation of cell proliferation but no increases in inflammatory mediator expression in cord blood RNA. CONCLUSIONS: In very preterm sheep fetuses, lipopolysaccharide stimulates inflammation in the fetal lung and fetal skin and stimulates a systemic inflammatory response that is not generated by fetal blood cells. These data argue for amniotic fluid-exposed tissues that play a key role in driving acute fetal and intrauterine inflammatory responses.

Successful combined intratumoral immunotherapy of established murine mesotheliomas requires B-cell involvement.

Combination immunotherapy has resulted in a number of impressive outcomes in mouse models and clinical settings. In this study, we report that a timed triple immunotherapy (TTI) protocol using 3 agonist antibodies (anti-CD25mAb, anti-TGF-ßmAb, and anti-CTLA-4mAb) produced complete clearance of established AB1 murine mesothelioma tumors. Combining all 3 agonist antibodies into a single cocktail for intratumoral injection was as effective as the TTI in tumor eradication. Cured mice showed elevated levels of tumor-specific IgG antibodies at 95 days posttreatment. Time-course studies of tumor clearance showed (1) that IgG levels were not elevated during tumor clearance and (2) that B-cell numbers were increased in the tumor-draining lymph nodes and spleens during tumor clearance. Finally, employment of B-cell knockout mice indicated a significant role for B cells in the successful eradication of the established tumors by the triple immunotherapy cocktail.

Effects of cytokine-suppressive anti-inflammatory drugs on inflammatory activation in ex vivo human and ovine fetal membranes.

Intrauterine infection and inflammation are responsible for the majority of early (<32 weeks) spontaneous preterm births (PTBs). Anti-inflammatory agents, delivered intra-amniotically together with antibiotics, may be an effective strategy for preventing PTB. In this study, the effects of four cytokine-suppressive anti-inflammatory drugs (CSAIDs: N-acetyl cysteine (NAC), SB239063, TPCA-1 and NEMO binding domain inhibitor (NBDI)) were assessed on human and ovine gestational membrane inflammation. Full-thickness membranes were collected from healthy, term, human placentas delivered by Caesarean section (n=5). Using a Transwell model, they were stimulated ex vivo with γ-irradiation-killed Escherichia coli applied to the amniotic face. Membranes from near-term, ovine placentas were stimulated in utero with lipopolysaccharide, Ureaplasma parvum or saline control and subjected to explant culture. The effects of treatment with CSAIDs or vehicle (1% DMSO) on accumulation of PGE2 and cytokines (human interleukin 6 (IL6), IL10 and TNFα; ovine IL8 (oIL8)) were assessed in conditioned media at various time points (3-20  h). In human membranes, the IKKß inhibitor TPCA-1 (7  µM) and p38 MAPK inhibitor SB239063 (20  µM) administered to the amniotic compartment were the most effective in inhibiting accumulation of cytokines and PGE2 in the fetal compartment. NAC (10  mM) inhibited accumulation of PGE2 and IL10 only; NBDI (10  µM) had no significant effect. In addition to the fetal compartment, SB239063 also exerted consistent and significant inhibitory effects in the maternal compartment. TPCA-1 and SB239063 suppressed oIL8 production, while all CSAIDs tested suppressed ovine PGE2 production. These results support the further investigation of intra-amniotically delivered CSAIDs for the prevention of inflammation-mediated PTB.

Polymyxin B agonist capture therapy for intrauterine inflammation: proof-of-principle in a fetal ovine model.

Intrauterine infection is a leading cause of preterm birth (PTB), most notably in deliveries occurring before 32 weeks gestation. Preterm infants exposed to intrauterine inflammation are more likely to have a host of neurological, respiratory, gastrointestinal, and visual pathologies. Preventing preterm delivery and protecting the fetus from injury is thus likely to require treatment of both intrauterine infection and inflammation. Polymyxin B (PMXB) is a cationic peptide antibiotic that binds Escherichia coli lipopolysaccharides (LPS) and prevents inflammatory activation. We hypothesized that intraamniotic administration of PMXB would selectively inhibit LPS-driven inflammation, serving as a proof-of-principle for targeted agonist capture therapy as a treatment for PTB and fetal injury. In vitro studies with primary fetal ovine keratinocytes demonstrated a significant and sustained reduction in tumor necrosis factor α and interleukin 8 messenger RNA expression after treatment with PMXB and LPS, relative to cells treated with LPS alone. In vivo studies with fetal sheep demonstrated a significant reduction in proinflammatory cytokines in the amniotic fluid and fetal lung (but not fetal skin or chorioamnion) in LPS + PMXB-treated animals, relative to those treated with LPS alone. These data are consistent with a partial resolution of LPS-driven intrauterine inflammation. They suggest the potential for agonist capture as a conceptual means of resolving the proparturition inflammation caused by infection of the amniotic cavity.

Topically applied Melaleuca alternifolia (tea tree) oil causes direct anti-cancer cytotoxicity in subcutaneous tumour bearing mice.

BACKGROUND: Melaleuca alternifolia (tea tree) oil (TTO) applied topically in a dilute (10%) dimethyl sulphoxide (DMSO) formulation exerts a rapid anti-cancer effect after a short treatment protocol. Tumour clearance is associated with skin irritation mediated by neutrophils which quickly and completely resolves upon treatment cessation. OBJECTIVE: To examine the mechanism of action underlying the anti-cancer activity of TTO. METHODS: Immune cell changes in subcutaneous tumour bearing mice in response to topically applied TTO treatments were assessed by flow cytometry and immunohistochemistry. Direct cytotoxicity of TTO on tumour cells in vivo was assessed by transmission electron microscopy. RESULTS: Neutrophils accumulate in the skin following topical 10% TTO/DMSO treatment but are not required for tumour clearance as neutrophil depletion did not abrogate the anti-cancer effect. Topically applied 10% TTO/DMSO, but not neat TTO, induces an accumulation and activation of dendritic cells and an accumulation of T cells. Although topical application of 10% TTO/DMSO appears to activate an immune response, anti-tumour efficacy is mediated by a direct effect on tumour cells in vivo. The direct cytotoxicity of TTO in vivo appears to be associated with TTO penetration. CONCLUSION: Future studies should focus on enhancing the direct cytotoxicity of TTO by increasing penetration through skin to achieve a higher in situ terpene concentration. This coupled with boosting a more specific anti-tumour immune response will likely result in long term clearance of tumours.

The Role of Regulatory T Cells in Mesothelioma.

Malignant mesothelioma (MM) appears to be responsive to immunotherapy. The lack of complete tumour cure as a result of many immunotherapies tested to date suggests that the immune response to MM is complex and multi-parametric. Regulatory T (Treg) cells are prevalent within murine and human mesotheliomas with their removal shown to result in tumour growth inhibition and the release of anti-tumour effector T cells from immunosuppression. The targeting of immune checkpoints as treatments for various solid tumours has recently shown promise in clinical settings. In addition, synergy between chemotherapy and immunotherapy has been demonstrated for many cancers, including mesothelioma. Here we demonstrate Treg cells as critical mediators of the anti-tumour immune response to MM and potential targets for anti-tumour immunotherapy; though the timing and dosage of Treg cell manipulating immunotherapies need to be optimised.

Tumour eradication and induction of memory against murine mesothelioma by combined immunotherapy.

Numerous immunotherapy treatments for cancer are undergoing clinical trials or are already approved for use. One particular area of interest is targeting mechanisms of immune tolerance. Using a murine model of mesothelioma, we investigated the roles of regulatory T-cells, intratumoural transforming growth factor (TGF)-ß and the negative regulator molecule cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) in immune tolerance to tumours. It was found that treatments targeting a single negative regulator molecule mechanism were not as effective against tumours as targeting multiple mechanisms simultaneously. Most importantly, it was found that a combined triple treatment of anti-CD25 monoclonal antibody (mAb), anti-CTLA-4 mAb and TGF-ß soluble receptor resulted in long-term clearance of tumours and memory against tumour rechallenge. These data suggest that clinical application of immunotherapies against tumours may be improved by simultaneously targeting multiple mechanisms of immune suppression.

Mechanisms of immune suppression exerted by regulatory T-cells in subcutaneous AE17 murine mesothelioma.

We have reported previously that a combined intratumoral treatment with anti-CD25mAb/transforming growth factor-ß (TGF-ß) soluble receptor induced regression of established and subcutaneous AE17 murine mesotheliomas. Here, we have investigated the mechanisms underlying this observation by analyzing the concentrations of interferon-γ (IFN-γ) and TGF-ß within tumors at various time points following single regulatory T-cell (T(reg)) depleting anti-CD25mAb, TGF-ß soluble receptor, or combined anti-CD25mAb/TGF-ß soluble receptor treatment. The combined treatment maintains the intratumoral TGF-ß concentration at a significantly lower level than either the untreated controls or the single anti-CD25mAb treatment alone. Also, the lower level of TGF-ß correlated with a significantly higher concentration of IFN-γ compared with the single anti-CD25mAb treatment. It was hypothesized that TGF-ß was the master regulator of immune suppression in the AE17 model of mesothelioma. However, it was found that although important, this cytokine alone is not responsible for maintaining immune suppression and that multiple mechanisms of suppression exist. Specifically, we have shown that the presence of T(regs) in the tumor draining lymph nodes alters the phenotype of dendritic cells in the same location. These data suggest that because the antitumor immune response is inhibited by multiple mechanisms of suppression, development of immunotherapeutic treatment regimes will be more successful if these mechanisms can be simultaneously inhibited.

Inhibition of established subcutaneous murine tumour growth with topical Melaleuca alternifolia (tea tree) oil.

PURPOSE: Systemic toxicity coupled with long treatment regimes of approved topical chemotherapeutic agents such as imiquimod and 5-fluorouracil (5-FU) are limiting. There is now more focus on the potential use of topical terpene agents as skin cancer treatments. Here, we show for the first time that topical Melaleuca alternifolia (tea tree) oil (TTO), abundant in terpenes, has in vivo antitumour activity. METHOD: Topical TTO formulations applied to immunocompetent tumour-bearing mice were assessed for antitumour efficacy by monitoring tumour growth and by histological analysis following treatment. RESULTS: Four, daily, topical treatments of 10% TTO/DMSO regressed subcutaneous AE17 mesotheliomas in mice for a period of 10 days and significantly retarded the growth of subcutaneous B16-F10 melanomas. The antitumour effect of topical 10% TTO/DMSO was accompanied by skin irritation similar to other topical chemotherapeutic agents, but unlike other approved topical agents, quickly and completely resolved. Furthermore, we show that topical 10% TTO/DMSO caused an influx of neutrophils and other immune effector cells in the treated area, with no evidence of systemic toxicity. CONCLUSION: TTO combined with an effective carrier significantly inhibited the growth of aggressive, subcutaneous, chemo-resistant tumours in immunocompetent mice. Taken together, these findings highlight the potential of topical TTO as an alternative topical antitumour treatment.

Combined intratumoral regulatory T-cell depletion and transforming growth factor-ß neutralization induces regression of established AE17 murine mesothelioma tumors.

Suppression of an anti-tumor immune response by regulatory T cells (T(regs)) in tumor-bearing hosts is now well established. Previously, we have reported that the intratumoral administration of T(reg)-depleting anti-CD25 monoclonal antibody every 10 days is highly effective at inhibiting the further development of established murine mesotheliomas. Here we investigate the dosage, kinetics, and immunology of this treatment. Further, we show that by precisely timing neutralization of transforming growth factor-ß (TGF-ß) within treated tumors using a TGF-ß-soluble receptor, the efficacy of the treatment can be significantly improved, resulting in tumor regression. We suggest that this combined intratumoral treatment approach can be applied clinically for the treatment of mesothelioma.

Alpha-Tocopheryl succinate: toxicity and lack of anti-tumour activity in immuno-competent mice.

Alpha-tocopheryl succinate (alpha-TOS), an analogue of vitamin E (VitE), inhibits peritoneal human malignant mesoethelioma xenograft development in immuno-compromised mice via the induction of apoptosis of tumour cells [Tomasetti, M., Gellert, N., Procopio, A., Neuzil, J., 2004. A vitamin E analogue suppresses malignant mesothelioma in a preclinical model: a future drug against a fatal neoplastic disease? Int. J. Cancer 109, 641-642]. We tested the effect of systemic alpha-TOS treatment in our immuno-competent and syngeneic murine mesothelioma model. VitE analogues such as alpha-TOS have been developed for clinical use as supplements mainly for the treatment of VitE deficiency and are considered safe and non-toxic when taken orally. In our murine model of mesothelioma alpha-TOS was not only ineffective at inhibiting established tumour development at the published doses, but resulted in severe side effects characterized by both behavioural changes, intra-peritoneal abnormalities and the destruction of T cells. Toxicity of alpha-TOS has not been reported to date perhaps due to a lack of studies conducted in fully immuno-competent hosts. Our results suggest that the translation of animal studies to clinical treatment with alpha-TOS requires careful consideration.