PGF2α induces a pro-labour phenotypical switch in human myometrial cells that can be inhibited with PGF2α receptor antagonists.

Preterm birth is the leading cause of infant morbidity and mortality. There has been an interest in developing prostaglandin F2α (PGF2α) antagonists as a new treatment for preterm birth, although much of the rationale for their use is based on studies in rodents where PGF2α initiates labour by regressing the corpus luteum and reducing systemic progesterone concentrations. How PGF2α antagonism would act in humans who do not have a fall in systemic progesterone remains unclear. One possibility, in addition to an acute stimulation of contractions, is a direct alteration of the myometrial smooth muscle cell state towards a pro-labour phenotype. In this study, we developed an immortalised myometrial cell line, MYLA, derived from myometrial tissue obtained from a pregnant, non-labouring patient, as well as a novel class of PGF2α receptor (FP) antagonist. We verified the functionality of the cell line by stimulation with PGF2α, resulting in Gαq-specific coupling and Ca2+ release, which were inhibited by FP antagonism. Compared to four published FP receptor antagonists, the novel FP antagonist N582707 was the most potent compound [Fmax 7.67 ± 0.63 (IC50 21.26 nM), AUC 7.30 ± 0.32 (IC50 50.43 nM), and frequency of Ca2+ oscillations 7.66 ± 0.41 (IC50 22.15 nM)]. RNA-sequencing of the MYLA cell line at 1, 3, 6, 12, 24, and 48 h post PGF2α treatment revealed a transforming phenotype from a fibroblastic to smooth muscle mRNA profile. PGF2α treatment increased the expression of MYLK, CALD1, and CNN1 as well as the pro-labour genes OXTR, IL6, and IL11, which were inhibited by FP antagonism. Concomitant with the inhibition of a smooth muscle, pro-labour transition, FP antagonism increased the expression of the fibroblast marker genes DCN, FBLN1, and PDGFRA. Our findings suggest that in addition to the well-described acute contractile effect, PGF2α transforms myometrial smooth muscle cells from a myofibroblast to a smooth muscle, pro-labour-like state and that the novel compound N582707 has the potential for prophylactic use in preterm labour management beyond its use as an acute tocolytic drug.

Pomalidomide and lenalidomide regulate erythropoiesis and fetal hemoglobin production in human CD34+ cells.

Sickle-cell disease (SCD) and beta thalassemia constitute worldwide public health problems. New therapies, including hydroxyurea, have attempted to augment the synthesis of fetal hemoglobin (HbF) and improve current treatment. Lenalidomide and pomalidomide are members of a class of immunomodulators used as anticancer agents. Because clinical trials have demonstrated that lenalidomide reduces or eliminates the need for transfusions in some patients with disrupted blood cell production, we investigated the effects of lenalidomide and pomalidomide on erythropoiesis and hemoglobin synthesis. We used an in vitro erythropoiesis model derived from human CD34+ progenitor cells from normal and SCD donors. We found that both compounds slowed erythroid maturation, increased proliferation of immature erythroid cells, and regulated hemoglobin transcription, resulting in potent induction of HbF without the cytotoxicity associated with other HbF inducers. When combined with hydroxyurea, pomalidomide and, to a lesser extent, lenalidomide were found to have synergistic effects on HbF upregulation. Our results elucidate what we believe to be a new mechanism of action of pomalidomide and lenalidomide and support the hypothesis that pomalidomide, used alone or in combination with hydroxyurea, may improve erythropoiesis and increase the ratio of fetal to adult hemoglobin. These findings support the evaluation of pomalidomide as an innovative new therapy for beta-hemoglobinopathies.

Immunomodulatory drugs reorganize cytoskeleton by modulating Rho GTPases.

IMiDs immunomodulatory drugs, including lenalidomide and pomalidomide represent a novel class of small molecule anticancer and anti-inflammatory drugs with broad biologic activities. However, the molecular mechanism through which these drugs exert their effects is largely undefined. Using pomalidomide and primary human monocytes, we report that pomalidomide rapidly and selectively activated RhoA and Rac1, but not Cdc42 or Ras, in the absence of any costimulation. Consistent with the activation of Rho GTPases, we found that pomalidomide enhanced F-actin formation, stabilized microtubules, and increased cell migration, all of which were blocked by selective inhibitors of ROCK1 and Rac1. Further, we showed that in Swiss 3T3 cells, pomalidomide only activated RhoA, not Rac1 or Cdc42, and potently induced stress fiber formation. The pomalidomide effect on actin cytoskeleton was blocked by the ROCK1 inhibitor, but not Rac1 inhibitor. Finally, we demonstrated that pomalidomide was able to regulate the activity of Rho GTPases and the formation of F-actin in primary human T cells as it did in monocytes and showed that the activation of RhoA was essential for pomalidomide-induced interleukin-2 expression in T cells. These novel activities provide what we believe a critical mechanism by which IMiDs drugs function as therapeutic immunomodulatory agents.

Bioluminescent imaging in induced mouse models of endometriosis reveals differences in four model variations.

Our understanding of the aetiology and pathophysiology of endometriosis remains limited. Disease modelling in the field is problematic as many versions of induced mouse models of endometriosis exist. We integrated bioluminescent imaging of 'lesions' generated using luciferase-expressing donor mice. We compared longitudinal bioluminescence and histology of lesions, sensory behaviour of mice with induced endometriosis and the impact of the gonadotropin-releasing hormone antagonist Cetrorelix on lesion regression and sensory behaviour. Four models of endometriosis were tested. We found that the nature of the donor uterine material was a key determinant of how chronic the lesions were, as well as their cellular composition. The severity of pain-like behaviour also varied across models. Although Cetrorelix significantly reduced lesion bioluminescence in all models, it had varying impacts on pain-like behaviour. Collectively, our results demonstrate key differences in the progression of the 'disease' across different mouse models of endometriosis. We propose that validation and testing in multiple models, each of which may be representative of the different subtypes/heterogeneity observed in women, should become a standard approach to discovery science in the field of endometriosis.

Lenalidomide and CC-4047 inhibit the proliferation of malignant B cells while expanding normal CD34+ progenitor cells.

Clinical studies involving patients with myelodysplastic syndromes or multiple myeloma have shown the efficacy of lenalidomide by reducing and often eliminating malignant cells while restoring the bone marrow function. To better understand these clinical observations, we investigated and compared the effects of lenalidomide and a structurally related analogue, CC-4047, on the proliferation of two different human hematopoietic cell models: the Namalwa cancer cell line and normal CD34+ progenitor cells. Both compounds had antiproliferative effects on Namalwa cells and pro-proliferative effects on CD34+ cells, whereas p21WAF-1 expression was up-regulated in both cell types. In Namalwa cells, the up-regulation of p21WAF-1 correlated well with the inhibition of cyclin-dependent kinase (CDK) 2, CDK4, and CDK6 activity leading to pRb hypophosphorylation and cell cycle arrest, whereas in CD34+ progenitor cells the increase of p21WAF-1 did not inhibit proliferation. Similarly, antiproliferation results were observed in two B lymphoma cell lines (LP-1 and U266) but interestingly not in normal B cells where a protection of apoptosis was found. Finally, CC-4047 and lenalidomide had synergistic effects with valproic acid [a histone deacetylase (HDAC) inhibitor] by increasing the apoptosis of Namalwa cells and enhancing CD34+ cell expansion. Our results indicate that lenalidomide and CC-4047 have opposite effects in tumor cells versus normal cells and could explain, at least in part, the reduction of malignant cells and the restoration of bone marrow observed in patients undergoing lenalidomide treatment. Moreover, this study provides new insights on the cellular pathways affected by lenalidomide and CC-4047, proposes new potential clinical uses, such as bone marrow regeneration, and suggests that the combination of lenalidomide or CC-4047 with certain HDAC inhibitors may elevate the therapeutic index in the treatment of hematologic malignancies.

Overexpression of type-1 adenylyl cyclase in mouse forebrain enhances recognition memory and LTP.

Cyclic AMP is a positive regulator of synaptic plasticity and is required for several forms of hippocampus-dependent memory including recognition memory. The type I adenylyl cyclase, Adcy1 (also known as AC1), is crucial in memory formation because it couples Ca(2+) to cyclic AMP increases in the hippocampus. Because Adcy1 is neurospecific, it is a potential pharmacological target for increasing cAMP specifically in the brain and for improving memory. We have generated transgenic mice that overexpress Adcy1 in the forebrain using the Camk2a (also known as alpha-CaMKII) promoter. These mice showed elevated long-term potentiation (LTP), increased memory for object recognition and slower rates of extinction for contextual memory. The increase in recognition memory and lower rates of contextual memory extinction may be due to enhanced extracellular signal-related kinase (ERK)/mitogen-activated protein kinase (MAPK) signaling, which is elevated in mice that overexpress Adcy1.

A Novel Triazolopyridine-Based Spleen Tyrosine Kinase Inhibitor That Arrests Joint Inflammation.

Autoantibodies and the immunoreceptors to which they bind can contribute to the pathogenesis of autoimmune diseases such as rheumatoid arthritis (RA). Spleen Tyrosine Kinase (Syk) is a non-receptor tyrosine kinase with a central role in immunoreceptor (FcR) signaling and immune cell functionality. Syk kinase inhibitors have activity in antibody-dependent immune cell activation assays, in preclinical models of arthritis, and have progressed into clinical trials for RA and other autoimmune diseases. Here we describe the characterization of a novel triazolopyridine-based Syk kinase inhibitor, CC-509. This compound is a potent inhibitor of purified Syk enzyme, FcR-dependent and FcR-independent signaling in primary immune cells, and basophil activation in human whole blood. CC-509 is moderately selective across the kinome and against other non-kinase enzymes or receptors. Importantly, CC-509 was optimized away from and has modest activity against cellular KDR and Jak2, kinases that when inhibited in a preclinical and clinical setting may promote hypertension and neutropenia, respectively. In addition, CC-509 is orally bioavailable and displays dose-dependent efficacy in two rodent models of immune-inflammatory disease. In passive cutaneous anaphylaxis (PCA), CC-509 significantly inhibited skin edema. Moreover, CC-509 significantly reduced paw swelling and the tissue levels of pro-inflammatory cytokines RANTES and MIP-1α in the collagen-induced arthritis (CIA) model. In summary, CC-509 is a potent, moderately selective, and efficacious inhibitor of Syk that has a differentiated profile when compared to other Syk compounds that have progressed into the clinic for RA.

Reduced anxiety and depression-like behavior in synaptotagmin IV (-/-) mice.

Synaptotagmin IV (Syt IV) is a secretory vesicle protein that is broadly expressed in brain and may function as a presynaptic regulator of synaptic release. Because Syt IV and abnormalities in neurotransmission have been implicated in psychiatric disease, we examined Syt IV (-/-) mice in animal models of mood-related behavior. We report that Syt IV (-/-) mice display lower levels of anxiety-like behavior in the elevated plus maze and enhanced locomotion in the open field. Syt IV (-/-) mice also exhibit reduced depression-like behavior and are highly sensitive to the effects of the anti-depressant imipramine in a modified Porsolt forced swim test. However, the physical restraint-induced stress hormone response is normal in Syt IV (-/-) mice. As judged by immunohistochemical criteria, the synaptic structure and connectivity of the hippocampus and raphe nucleus in Syt IV (-/-) mice are indistinguishable from wild-type littermates. These results indicate that Syt IV plays a role in rodent mood-related behavior and suggests Syt IV regulates synaptic function in the neuronal networks that modulate these behaviors.

Attenuation of ozone-induced airway inflammation and hyper-responsiveness by c-Jun NH2 terminal kinase inhibitor SP600125.

Ozone has potent oxidizing properties, and exposure to ozone causes airway hyper-responsiveness (AHR) and lung inflammation. We determined the importance of c-Jun NH(2) terminal kinase (JNK), a member of the mitogen-activated protein kinase pathway, in ozone-induced AHR and inflammation. SP600125 [anthra[1,9-cd] pyrazol-6 (2H)-one], a specific JNK inhibitor (30 mg/kg) or vehicle, was administered by intraperitoneal injection before and after ozone exposure (3 ppm for 3 h). SP600125 significantly reduced total cells, and neutrophils in bronchoalveolar fluid recovered at 20 to 24 h after exposure and inhibited ozone-induced AHR. Ozone exposure induced activation of JNK in the lung as measured by the expression of phosphorylated-c-Jun, an effect abolished by SP600125. Gene-microarray analysis revealed that ozone increased the expression of over 400 genes by more than 2-fold, including interleukin-6 (IL-6), CXCL1 (keratinocyte cytokine), and CCL2 (monocyte chemoattractant protein-1). SP600125 modulated the expression of a subset of 29 ozone-induced genes; IL-6 and CCL2 expression were further increased, whereas the expression of metallothionein 1, hemopexin, and mitogen-activated 3 kinase 6 was decreased in SP600125-treated ozone-exposed mice. Changes in mRNA for IL-6, CXCL1, and CCL2 were confirmed by real-time polymerase chain reaction. Ozone also decreased the expression of over 500 genes, with the most potent effect on angiopoietin-1. SP600125 modulated the expression of 15 of these genes, and in particular, SP600125 reversed ozone-induced decrease in expression of the redox-sensitive transcription factor, hypoxia-induced factor-1alpha. This study highlights an important role for JNK in response to oxidative stress through modulation of specific inflammatory and redox mediators. Inhibition of JNK with small molecule kinase inhibitors may be a means of reducing ozone-induced inflammation and AHR.

Immunomodulatory drug CC-4047 is a cell-type and stimulus-selective transcriptional inhibitor of cyclooxygenase 2.

COX2 (prostaglandin G/H synthase, PTGS2) is a well-validated target in the fields of both oncology and inflammation. Despite their significant toxicity profile, non-steroidal anti-inflammatory drugs (NSAIDs) have become standard of care in the treatment of many COX2-mediated inflammatory conditions. In this report, we show that one IMiDs((R)) immunomodulatory drug, CC-4047, can reduce the levels of COX2 and the production of prostaglandins (PG) in human LPS-stimulated monocytes. The inhibition of COX2 by CC-4047 occurs at the level of gene transcription, by reducing the LPS-stimulated transcriptional activity at the COX2 gene. Because it is a transcriptional rather than an enzymatic inhibitor of COX2, CC-4047 inhibition of PG production is not susceptible to competition by exogenous arachadonic acid (AA). The distinct mechanisms of action allow CC-4047 and a COX2-selective NSAID to work additively to block PG secretion from monocytes. CC-4047 does not, however, block COX2 induction in or prostacyclin secretion from IL-1beta stimulated human umbilical vein endothelial cells (HUVEC) cells, nor does it inhibit COX1 in either monocytes or HUVEC cells. CC-4047 also inhibits COX2 and PG production in monocytes derived from patients with sickle cell disease (SCD). Taken together, the data in this manuscript suggest CC-4047 will provide important anti-inflammatory benefit to patients and will improve the safety of NSAIDs in the treatment of SCD or other inflammatory conditions.

Why calcium-stimulated adenylyl cyclases?

The Ca(2+)/calmodulin-stimulated adenylyl cyclases, AC1 and AC8, play a critical role in several forms of neuroplasticity, including long-lasting long-term potentiation (L-LTP) and long-term memory (LTM). By coupling neuronal activity and Ca(2+) increases to the production of cAMP, AC1 and AC8 activate cAMP-dependent signal transduction and transcriptional pathways critical for L-LTP and LTM.

Altered hippocampal short-term plasticity and associative memory in synaptotagmin IV (-/-) mice.

Synaptotagmin IV (Syt IV) is an activity-inducible, secretory vesicle protein that is thought to function as an inhibitor of neurotransmitter release (Littleton et al. Nature 400:757-760, 1999). To test this hypothesis in neurons of the mammalian CNS, we measured field excitatory postsynaptic potentials (fEPSPs) in hippocampal slice preparations from Syt IV (-/-) mice. At Schaffer collateral synapses, the basal properties of neurotransmission are largely normal. However, two forms of short-term plasticity, paired-pulse facilitation (PPF) and post-tetanic potentiation (PTP), are significantly enhanced in area CA1 of Syt IV (-/-) slices. Similarly, the early stages of long-term potentiation (LTP) are also enhanced at these synapses. Consistent with the low levels of Syt IV observed in dentate granule cells, the mossy fiber synapses in Syt IV (-/-) slices display largely normal PPF and LTP. In addition, we find that Syt IV (-/-) mice have deficits in the associative passive avoidance memory paradigm, but are normal in the novel object recognition paradigm. The synaptic architecture and connectivity of Syt IV (-/-) brains is indistinguishable from wild-type mice as indicated by immunohistochemical analysis. These results suggest Syt IV is a presynaptic negative regulator of short-term plasticity in area CA1 of the hippocampus and is required for some, but not all, forms of hippocampus-dependent memory.