Tiziana Cotechini

Gut microbiome modulates response to anti-PD-1 immunotherapy in melanoma patients.

Good bacteria help fight cancer Resident gut bacteria can affect patient responses to cancer immunotherapy (see the Perspective by Jobin). Routy et al. show that antibiotic consumption is associated with poor response to immunotherapeutic PD-1 blockade. They profiled samples from patients with lung and kidney cancers and found that nonresponding patients had low levels of the bacterium Akkermansia muciniphila. Oral supplementation of the bacteria to antibiotic-treated mice restored the response to immunotherapy. Matson et al. and Gopalakrishnan et al. studied melanoma patients receiving PD-1 blockade and found a greater abundance of “good” bacteria in the guts of responding patients. Nonresponders had an imbalance in gut flora composition, which correlated with impaired immune cell activity. Thus, maintaining healthy gut flora could help patients combat cancer. Science, this issue p. 91, p. 104, p. 97; see also p. 32 Gut bacteria influence patient response to cancer therapy. Preclinical mouse models suggest that the gut microbiome modulates tumor response to checkpoint blockade immunotherapy; however, this has not been well-characterized in human cancer patients. Here we examined the oral and gut microbiome of melanoma patients undergoing anti–programmed cell death 1 protein (PD-1) immunotherapy (n = 112). Significant differences were observed in the diversity and composition of the patient gut microbiome of responders versus nonresponders. Analysis of patient fecal microbiome samples (n = 43, 30 responders, 13 nonresponders) showed significantly higher alpha diversity (P < 0.01) and relative abundance of bacteria of the Ruminococcaceae family (P < 0.01) in responding patients. Metagenomic studies revealed functional differences in gut bacteria in responders, including enrichment of anabolic pathways. Immune profiling suggested enhanced systemic and antitumor immunity in responding patients with a favorable gut microbiome as well as in germ-free mice receiving fecal transplants from responding patients. Together, these data have important implications for the treatment of melanoma patients with immune checkpoint inhibitors.

Inflammation in rat pregnancy inhibits spiral artery remodeling leading to fetal growth restriction and features of preeclampsia

Abnormal maternal inflammation leads to TNF-mediated fetal growth restriction and some features of preeclampsia that can be ameliorated with the nitric oxide mimetic nitroglycerin.

Spontaneous Pregnancy Loss Mediated by Abnormal Maternal Inflammation in Rats Is Linked to Deficient Uteroplacental Perfusion

Abnormal maternal inflammation during pregnancy is associated with spontaneous pregnancy loss and intrauterine fetal growth restriction. However, the mechanisms responsible for these pregnancy outcomes are not well understood. In this study, we used a rat model to demonstrate that pregnancy loss resulting from aberrant maternal inflammation is closely linked to deficient placental perfusion. Administration of LPS to pregnant Wistar rats on gestational day 14.5, to induce maternal inflammation, caused fetal loss in a dose-dependent manner 3–4 h later, and surviving fetuses were significantly growth restricted. Pregnancy loss was associated with coagulopathy, structural abnormalities in the uteroplacental vasculature, decreased placental blood flow, and placental and fetal hypoxia within 3 h of LPS administration. This impairment in uteroplacental hemodynamics in LPS-treated rats was linked to increased uterine artery resistance and reduced spiral arteriole flow velocity. Pregnancy loss induced by LPS was prevented by maternal administration of the immunoregulatory cytokine IL-10 or by blocking TNF-α activity after treatment with etanercept (Enbrel). These results indicate that alterations in placental perfusion are responsible for fetal morbidities associated with aberrant maternal inflammation and support a rationale for investigating a potential use of immunomodulatory agents in the prevention of spontaneous pregnancy loss.

Hypoxia induces escape from innate immunity in cancer cells via increased expression of ADAM10: role of nitric oxide

One key to malignant progression is the acquired ability of tumor cells to escape immune-mediated lysis. Whereas tumor hypoxia is known to play a causal role in cancer metastasis and resistance to therapy, the link between hypoxia and immune escape in cancer remains poorly understood. Here, we show that hypoxia induces tumor cell resistance to lysis mediated by immune effectors and that this resistance to lysis occurs via a hypoxia-inducible factor-1 (HIF-1)-dependent pathway linked to increased expression of the metalloproteinase ADAM10. This enzyme is required for the hypoxia-induced shedding of MHC class I chain-related molecule A (MICA), a ligand that triggers the cytolytic action of immune effectors, from the surface of tumor cells. Indeed, our findings show a mechanistic link between hypoxia-induced accumulation of the α-subunit of HIF-1 (HIF-1α), increased expression of ADAM10, and decreased surface MICA levels leading to tumor cell resistance to lysis mediated by innate immune effectors. Nitric oxide mimetic agents interfered with the hypoxia-induced accumulation of HIF-1α and with the hypoxia-induced upregulation of ADAM10 expression required for decreased surface MICA expression and resistance to lysis. Furthermore, treatment of tumor-bearing mice with nitroglycerin, a nitric oxide mimetic, attenuated tumor growth by a mechanism that relied upon innate immune effector cells. Together, these findings reveal a novel mechanism by which the hypoxic tumor microenvironment contributes to immune escape in cancer, lending support to potential immunotherapeutic strategies involving the use of nitric oxide mimetics.

Activation of the PD-1/PD-L1 immune checkpoint confers tumor cell chemoresistance associated with increased metastasis

The ability of tumor cells to avoid immune destruction (immune escape) as well as their acquired resistance to anti-cancer drugs constitute important barriers to the successful management of cancer. Interaction between the Programmed Death Ligand 1 (PD-L1) on the surface of tumor cells with the Programmed Death-1 (PD-1) receptor on cytotoxic T lymphocytes leads to inactivation of these immune effectors and, consequently, immune escape. Here we show that the PD-1/PD-L1 axis also leads to tumor cell resistance to conventional chemotherapeutic agents. Using a panel of PD-L1-expressing human and mouse breast and prostate cancer cell lines, we found that incubation of breast and prostate cancer cells in the presence of purified recombinant PD-1 resulted in resistance to doxorubicin and docetaxel as determined using clonogenic survival assays. Co-culture with PD-1-expressing Jurkat T cells also promoted chemoresistance and this was prevented by antibody blockade of either PD-L1 or PD-1 or by silencing of the PD-L1 gene. Moreover, inhibition of the PD-1/PD-L1 axis using anti-PD-1 antibody enhanced doxorubicin chemotherapy to inhibit metastasis in a syngeneic mammary orthotopic mouse model of metastatic breast cancer. To further investigate the mechanism of tumor cell survival advantage upon PD-L1 ligation, we show that exposure to rPD-1 promoted ERK and mTOR growth and survival pathways leading to increased cell proliferation. Overall, the findings of this study indicate that combinations of chemotherapy and immune checkpoint blockade may limit chemoresistance and progression to metastatic disease.

Aberrant maternal inflammation as a cause of pregnancy complications: A potential therapeutic target?

Pre-eclampsia (PE), fetal growth restriction (FGR), pre-term labour and fetal death are common complications of pregnancy often associated with abnormal maternal inflammation. Though the precise causes of these complications remain obscure, altered maternal blood flow to the placenta is an underlying hallmark, especially with respect to the pathogenesis of PE, FGR and fetal demise. Furthermore, deficient trophoblast-mediated spiral artery remodelling is often cited as the primary cause of impaired utero-placental perfusion. Considerably less attention has been directed towards investigating other factors, including maternal vasoconstriction or hemostatic alterations, as contributors to poor utero-placental perfusion. This review provides a rationale for investigating the role of abnormal maternal inflammation in the pathophysiology of pregnancy complications including PE, FGR and fetal demise. In particular, the association between aberrant maternal inflammation and inadequate utero-placental perfusion is considered in the context of inflammation-associated alterations in maternal hemostasis and vasoconstriction. Finally, the role of aberrant maternal inflammation as a cause of local oxidative/nitrosative stress is examined and the possibility of targeting deficient nitric oxide signalling as a therapeutic intervention for the treatment of inflammation-associated pregnancy complications is discussed.

IFPA Meeting 2010 Workshops Report II: Placental pathology; trophoblast invasion; fetal sex; parasites and the placenta; decidua and embryonic or fetal loss; trophoblast differentiation and syncytialisation

Workshops are an important part of the IFPA annual meeting. At IFPA Meeting 2010 diverse topics were discussed in twelve themed workshops, six of which are summarized in this report. 1. The placental pathology workshop focused on clinical correlates of placenta accreta/percreta. 2. Mechanisms of regulation of trophoblast invasion and spiral artery remodeling were discussed in the trophoblast invasion workshop. 3. The fetal sex and intrauterine stress workshop explored recent work on placental sex differences and discussed them in the context of whether boys live dangerously in the womb.4. The workshop on parasites addressed inflammatory responses as a sign of interaction between placental tissue and parasites. 5. The decidua and embryonic/fetal loss workshop focused on key regulatory mediators in the decidua, embryo and fetus and how alterations in expression may contribute to different diseases and adverse conditions of pregnancy. 6. The trophoblast differentiation and syncytialisation workshop addressed the regulation of villous cytotrophoblast differentiation and how variations may lead to placental dysfunction and pregnancy complications.

IFPA Meeting 2011 workshop report II: Angiogenic signaling and regulation of fetal endothelial function; placental and fetal circulation and growth; spiral artery remodeling

Workshops are an important part of the IFPA annual meeting as they allow for discussion of specialized topics. At IFPA meeting 2011 there were twelve themed workshops, three of which are summarized in this report. These workshops related to vascular systems and circulation in the mother, placenta and fetus, and were divided in to 1) angiogenic signaling and regulation of fetal endothelial function; 2) placental and fetal circulation and growth; 3) spiral artery remodeling.

Abnormal inflammation leads to maternal coagulopathies associated with placental haemostatic alterations in a rat model of foetal loss

Spontaneous pregnancy loss is often associated with aberrant maternal inflammation and systemic coagulopathies. However, the role of inflammation in the development of obstetric coagulopathies is poorly understood. Further, questions remain as to whether systemic coagulopathies are linked to placental haemostatic alterations, and whether these local alterations contribute to a negative foetal outcome. Using a model of spontaneous foetal loss in which pregnant rats are given a single injection of bacterial lipopolysaccharide (LPS), we characterised the systemic maternal coagulation status following LPS administration using thromboelastography (TEG), a global haemostatic assay that measures the kinetics of clot formation. Systemic maternal coagulopathy was evident in 82% of LPS-treated rats. Specifically, we observed stage-I, -II, and -III disseminated intravascular coagulation (DIC) and hypercoagulability. Modulation of inflammation through inhibition of tumour necrosis factor α with etanercept resulted in a 62% reduction in the proportion of rats exhibiting coagulopathy. Moreover, inflammation-induced systemic coagulopathies were associated with placental haemostatic alterations, which included increased intravascular, decidual, and labyrinth fibrin deposition in cases of DIC-I and hypercoagulability, and an almost complete absence of fibrin deposition in cases of DIC-III. Furthermore, systemic and placental haemostatic alterations were associated with impaired utero-placental haemodynamics, and inhibition of these haemostatic alterations by etanercept was associated with maintenance of utero-placental haemodynamics. These findings indicate that modulation of maternal inflammation may be useful in the prevention of coagulopathies associated with complications of pregnancy.

Inflammation-induced fetal growth restriction in rats is associated with altered placental morphometrics

INTRODUCTION Evidence links alterations in placental shape and size to fetal growth restriction (FGR). Here we determined whether alterations in placental morphometrics are linked to FGR induced by abnormal maternal inflammation. METHODS We used an inflammation-induced model of FGR in which pregnant rats receive lipopolysaccharide (LPS) on gestational days (GD) 13.5-16.5. Fetal weights were matched to various parameters of placental morphometrics including weight, area, minor and major axes lengths and thickness. RESULTS Compared with saline administration, LPS administration was associated with altered placental morphometrics, including reduced placental weight, decreased placental area and a trend towards reduced placental thickness. When data were dichotomized as FGR or normal-sized fetuses within treatment groups, a significant increase in the placental-weight-to-fetal-weight ratio and placental thickness was observed only in the saline-associated FGR subgroup. Multivariable linear regression revealed that the lengths of the major and minor placental axes were predictors of fetal weight, regardless of treatment modality. Subgroup regression analysis by treatment revealed that the lengths of the major and minor placental axes were predictors of fetal weight in the saline-treatment group while only the minor placental axis was a predictor of fetal weight in the LPS cohort. Finally, placental area and the length of the minor placental axis were correlated with implantation site location only in the saline-treatment group. DISCUSSION/CONCLUSION These findings indicate that inflammation-induced FGR is associated with alterations in placental morphometrics. Our data reveal that the mechanisms leading to inflammation-induced FGR may be different from the mechanisms leading to idiopathic FGR.