Pomalidomide is nonteratogenic in chicken and zebrafish embryos and nonneurotoxic in vitro

Rapamycin vs TORin-1 or Gleevec vs Nilotinib: Simple chemical evolution that converts PAK1-blockers to TOR-blockers or vice versa?

Both PAK1 (RAC/CDC42-activating kinase 1) and TOR (Target of Rapamycin) are among the major oncogenic/ageing kinases. However, they play the opposite role in our immune system, namely immune system is suppressed by PAK1, while it requires TOR. Thus, PAK1-blockers, would be more effective for therapy of cancers, than TOR-blockers. Since 2015 when we discovered genetically that PDGF-induced melanogenesis depends on "PAK1", we are able to screening a series of PAK1-blockers as melanogenesis-inhibitors which could eventually promote longevity. Interestingly, rapamycin, the first TOR-inhibitor, promotes melanogenesis, clearly indicating that TOR suppresses melanogenesis. However, a new TOR-inhibitor called TORin-1 no longer suppresses immune system, and blocks melanogenesis in cell culture. These observations strongly indicate that TORin-1 acts as PAK1-blockers, instead of TOR-blockers, in vivo. Thus, it is most likely that melanogenesis in cell culture could enable us to discriminate PAK1-blockers from TORblockers.

Pomalidomide Improves Motor Behavioral Deficits and Protects Cerebral Cortex and Striatum Against Neurodegeneration Through a Reduction of Oxidative/Nitrosative Damages and Neuroinflammation After Traumatic Brain Injury

Neuronal damage resulting from traumatic brain injury (TBI) causes disruption of neuronal projections and neurotransmission that contribute to behavioral deficits. Cellular generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) is an early event following TBI. ROS often damage DNA, lipids, proteins, and carbohydrates while RNS attack proteins. The products of lipid peroxidation 4-hydroxynonenal (4-HNE) and protein nitration 3-nitrotyrosine (3-NT) are often used as indicators of oxidative and nitrosative damages, respectively. Increasing evidence has shown that striatum is vulnerable to damage from TBI with a disturbed dopamine neurotransmission. TBI results in neurodegeneration, oxidative stress, neuroinflammation, neuronal apoptosis, and autophagy in the striatum and contribute to motor or behavioral deficits. Pomalidomide (Pom) is a Food and Drug Administration (FDA)-approved immunomodulatory drug clinically used in treating multiple myeloma. We previously showed that Pom reduces neuroinflammation and neuronal death induced by TBI in rat cerebral cortex. Here, we further compared the effects of Pom in cortex and striatum focusing on neurodegeneration, oxidative and nitrosative damages, as well as neuroinflammation following TBI. Sprague-Dawley rats subjected to a controlled cortical impact were used as the animal model of TBI. Systemic administration of Pom (0.5 mg/kg, intravenous [i.v.]) at 5 h post-injury alleviated motor behavioral deficits, contusion volume at 24 h after TBI. Pom alleviated TBI-induced neurodegeneration stained by Fluoro-Jade C in both cortex and striatum. Notably, Pom treatment reduces oxidative and nitrosative damages in cortex and striatum and is more efficacious in striatum (93% reduction in 4-HNE-positive and 84% reduction in 3-NT-positive neurons) than in cerebral cortex (42% reduction in 4-HNE-positive and 55% reduction in 3-NT-positive neurons). In addition, Pom attenuated microgliosis, astrogliosis, and elevations of proinflammatory cytokines in cortical and striatal tissue. We conclude that Pom may contribute to improved motor behavioral outcomes after TBI through targeting oxidative/nitrosative damages and neuroinflammation.

Myeloid cells interact with a subset of thyrocytes to promote their migration and follicle formation through NF-κB

The pathogenesis of thyroid dysgenesis (TD) is not well understood. Here, using a combination of single-cell RNA and spatial transcriptome sequencing, we identify a subgroup of NF-κB-activated thyrocytes located at the center of thyroid tissues in postnatal mice, which maintained a partially mesenchymal phenotype. These cells actively protruded out of the thyroid primordium and generated new follicles in zebrafish embryos through continuous tracing. Suppressing NF-κB signaling affected thyrocyte migration and follicle formation, leading to a TD-like phenotype in both mice and zebrafish. Interestingly, during thyroid folliculogenesis, myeloid cells played a crucial role in promoting thyrocyte migration by maintaining close contact and secreting TNF-α. We found that cebpa mutant zebrafish, in which all myeloid cells were depleted, exhibited thyrocyte migration defects. Taken together, our results suggest that myeloid-derived TNF-α-induced NF-κB activation plays a critical role in promoting the migration of vertebrate thyrocytes for follicle generation.

Novel promising benzoxazole/benzothiazole-derived immunomodulatory agents: Design, synthesis, anticancer evaluation, and in silico ADMET analysis

Eleven novel benzoxazole/benzothiazole-based thalidomide analogs were designed and synthesized to obtain new effective antitumor immunomodulatory agents. The synthesized compounds were evaluated for their cytotoxic activities against HepG-2, HCT-116, PC3, and MCF-7 cells. Generally, the open analogs with semicarbazide and thiosemicarbazide moieties (10, 13a-c, 14, and 17a,b) exhibited higher cytotoxic activities than derivatives with closed glutarimide moiety (8a-d). In particular, compound 13a (IC50  = 6.14, 5.79, 10.26, and 4.71 µM against HepG-2, HCT-116, PC3, and MCF-7, respectively) and 14 (IC50  = 7.93, 8.23, 12.37, and 5.43 µM, respectively) exhibited the highest anticancer activities against the four tested cell lines. The most active compounds 13a and 14 were further evaluated for their in vitro immunomodulatory activities on tumor necrosis factor-alpha (TNF-α), caspase-8 (CASP8), vascular endothelial growth factor (VEGF), and nuclear factor kappa-B p65 (NF-κB p65) in HCT-116 cells. Compounds 13a and 14 showed a remarkable and significant reduction in TNF-α. Furthermore, they showed significant elevation in CASP8 levels. Also, they significantly inhibited VEGF. In addition, compound 13a showed significant decreases in the level of NF-κB p65 while compound 14 demonstrated an insignificant decrease with respect to thalidomide. Moreover, our derivatives exhibited good in silico absorption, distribution, metabolism, elimination, toxicity (ADMET) profiles.

Lenalidomide derivatives and proteolysis-targeting chimeras for controlling neosubstrate degradation

Lenalidomide, an immunomodulatory drug (IMiD), is commonly used as a first-line therapy in many haematological cancers, such as multiple myeloma (MM) and 5q myelodysplastic syndromes (5q MDS), and it functions as a molecular glue for the protein degradation of neosubstrates by CRL4CRBN. Proteolysis-targeting chimeras (PROTACs) using IMiDs with a target protein binder also induce the degradation of target proteins. The targeted protein degradation (TPD) of neosubstrates is crucial for IMiD therapy. However, current IMiDs and IMiD-based PROTACs also break down neosubstrates involved in embryonic development and disease progression. Here, we show that 6-position modifications of lenalidomide are essential for controlling neosubstrate selectivity; 6-fluoro lenalidomide induced the selective degradation of IKZF1, IKZF3, and CK1α, which are involved in anti-haematological cancer activity, and showed stronger anti-proliferative effects on MM and 5q MDS cell lines than lenalidomide. PROTACs using these lenalidomide derivatives for BET proteins induce the selective degradation of BET proteins with the same neosubstrate selectivity. PROTACs also exert anti-proliferative effects in all examined cell lines. Thus, 6-position-modified lenalidomide is a key molecule for selective TPD using thalidomide derivatives and PROTACs.

Design, Synthesis, and Biological Evaluation of New Potential Unusual Modified Anticancer Immunomodulators for Possible Non-Teratogenic Quinazoline-Based Thalidomide Analogs

Sixteen new thalidomide analogs were synthesized. The new candidates showed potent in vitro antiproliferative activities against three human cancer cell lines, namely hepatocellular carcinoma (HepG-2), prostate cancer (PC3), and breast cancer (MCF-7). It was found that compounds XII, XIIIa, XIIIb, XIIIc, XIIId, XIVa, XIVb, and XIVc showed IC50 values ranging from 2.03 to 13.39 µg/mL, exhibiting higher activities than thalidomide against all tested cancer cell lines. Compound XIIIa was the most potent candidate, with an IC50 of 2.03 ± 0.11, 2.51 ± 0.2, and 0.82 ± 0.02 µg/mL compared to 11.26 ± 0.54, 14.58 ± 0.57, and 16.87 ± 0.7 µg/mL for thalidomide against HepG-2, PC3, and MCF-7 cells, respectively. Furthermore, compound XIVc reduced the expression of NFκB P65 levels in HepG-2 cells from 278.1 pg/mL to 63.1 pg/mL compared to 110.5 pg/mL for thalidomide. Moreover, compound XIVc induced an eightfold increase in caspase-8 levels with a simultaneous decrease in TNF-α and VEGF levels in HepG-2 cells. Additionally, compound XIVc induced apoptosis and cell cycle arrest. Our results reveal that the new candidates are potential anticancer candidates, particularly XIIIa and XIVc. Consequently, they should be considered for further evaluation for the development of new anticancer drugs.

A New Generation of IMiDs as Treatments for Neuroinflammatory and Neurodegenerative Disorders

The immunomodulatory imide drug (IMiD) class, which includes the founding drug member thalidomide and later generation drugs, lenalidomide and pomalidomide, has dramatically improved the clinical treatment of specific cancers, such as multiple myeloma, and it combines potent anticancer and anti-inflammatory actions. These actions, in large part, are mediated by IMiD binding to the human protein cereblon that forms a critical component of the E3 ubiquitin ligase complex. This complex ubiquitinates and thereby regulates the levels of multiple endogenous proteins. However, IMiD-cereblon binding modifies cereblon's normal targeted protein degradation towards a new set of neosubstrates that underlies the favorable pharmacological action of classical IMiDs, but also their adverse actions-in particular, their teratogenicity. The ability of classical IMiDs to reduce the synthesis of key proinflammatory cytokines, especially TNF-α levels, makes them potentially valuable to reposition as drugs to mitigate inflammatory-associated conditions and, particularly, neurological disorders driven by an excessive neuroinflammatory element, as occurs in traumatic brain injury, Alzheimer's and Parkinson's diseases, and ischemic stroke. The teratogenic and anticancer actions of classical IMiDs are substantial liabilities for effective drugs in these disorders and can theoretically be dialed out of the drug class. We review a select series of novel IMiDs designed to avoid binding with human cereblon and/or evade degradation of downstream neosubstrates considered to underpin the adverse actions of thalidomide-like drugs. These novel non-classical IMiDs hold potential as new medications for erythema nodosum leprosum (ENL), a painful inflammatory skin condition associated with Hansen's disease for which thalidomide remains widely used, and, in particular, as a new treatment strategy for neurodegenerative disorders in which neuroinflammation is a key component.

Design, synthesis, anticancer evaluation, in silico docking and ADMET analysis of novel indole-based thalidomide analogs as promising immunomodulatory agents

In the present work, novel 16 indole-based thalidomide analogs were designed and synthesized to obtain new effective antitumor immunomodulatory agents. The synthesized compounds were evaluated for their cytotoxic activities against HepG-2, HCT-116, PC3 and MCF-7 cell lines. Generally, the opened analogs of glutarimide ring exhibited higher activities than the closed ones. Compounds 21a-b and 11d,g showed strong potencies against all tested cell lines with IC50 values ranging from 8.27 to 25.20 µM comparable to that of thalidomide (IC50 values ranging from 32.12 to 76.91 µM). The most active compounds were further evaluated for their in vitro immunomodulatory activities via estimation of human tumor necrosis factor alpha (TNF-α), human caspase-8 (CASP8), human vascular endothelial growth factor (VEGF), and nuclear factor kappa-B P65 (NF-κB P65) in HCT-116 cells. Thalidomide was used as a positive control. Compounds 11g, 21a and 21b showed remarkable significant reduction in TNF-α. Furthermore, compounds 11g, 21a and 21b showed significant elevation in CASP8 levels. Compounds 11g and 21a significantly inhibited VEGF. In addition, derivatives 11d, 11g and 21a showed significant decrease in level of NF-κB p65. Moreover, our derivatives exhibited good in silico docking and ADMET profile.Communicated by Ramaswamy H. Sarma.

Thalidomide Attenuates Skin Lesions and Inflammation in Rosacea-Like Mice Induced by Long-Term Exposure of LL-37

Purpose

Most of the existing studies focus on the early inflammation of rosacea, with few interventions on the later development of fibrosis and the relationship between thalidomide and rosacea. The purpose of this study was to construct a long-term induction model and explore the effects of thalidomide on the later stage of inflammation and early stage of fibrosis in rosacea.

Patients and Methods

BALB/c male mice were randomly divided into four groups: control group, control plus thalidomide group, LL-37 group and LL-37 plus thalidomide group, Intradermal and intraperitoneal injections were given. After repeated induction, skin changes were recorded by taking photos. The animals were sacrificed, the back skin was used for HE staining and VG staining to detect histomorphological characteristics. Immunofluorescence staining and Western blot were used to detect the expression of inflammatory and fibrosis-related factors.

Results

The results were compared with the early stage of the model, wherein the skin inflammation of the 20-day mice was more obvious with a trend of fibrosis. Compared with the control group, histopathological examination showed that the inflammatory cell infiltration in the LL-37 group was significantly increased, and the skin was thickened with collagen deposition. LL-37 induction significantly increased the expression of inflammatory markers (eg, TNF-α and IL-1β) and fibrotic markers (eg, COL1, α-SMA, vimentin and N-Cadherin). Intervention with thalidomide significantly reduced erythema, inflammatory cell infiltration, collagen deposition, and down-regulate the expression of inflammation and fibrosis related factors in rosacea mice.

Conclusion

The long-term continuous induction of LL-37 in mice could simulate the occurrence and development of rosacea, and thalidomide could ameliorate the rosacea induced by long-term exposure to LL-37 by regulating inflammatory infiltration, collagen deposition and fibrosis-related processes.

Molecular and Structural Characterization of Lenalidomide-Mediated Sequestration of eIF3i

Lenalidomide is a ligand of the E3 ligase substrate adapter cereblon (CRBN) that achieves its clinical effects in part by the promotion of substrate recruitment and degradation. In contrast to prior targets, eIF3i is recruited but not degraded upon complex formation with lenalidomide and CRBN, although the structural details and mechanistic outcomes of this interaction are unresolved. Here, we characterize the structural basis and mechanistic outcomes of lenalidomide-induced sequestration of eIF3i from the eIF3 complex. Identification of the binding interface on eIF3i by a covalent lenalidomide probe and mass spectrometry rationalizes the sequestration event. We further connect eIF3i and CRBN to lenalidomide-driven effects on angiogenic markers, Akt1 phosphorylation, and associated antiangiogenesis phenotypes. Finally, we find that eIF3i sequestration is observed in MM.1S and MOLM13 cells after the degradation of other substrates, such as IKZF1. The defined binding interface elucidated by chemical proteomics and the observation of eIF3i sequestration as a lenalidomide function open future directions in designing new chemical adapters for protein sequestration as a strategy to selectively control protein functions.

Role of chronic neuroinflammation in neuroplasticity and cognitive function: A hypothesis

OBJECTIVE

Evaluating the efficacy of 3,6'-dithioPomalidomide in 5xFAD Alzheimer's disease (AD) mice to test the hypothesis that neuroinflammation is directly involved in the development of synaptic/neuronal loss and cognitive decline.

BACKGROUND

Amyloid-β (Aβ) or tau-focused clinical trials have proved unsuccessful in mitigating AD-associated cognitive impairment. Identification of new drug targets is needed. Neuroinflammation is a therapeutic target in neurodegenerative disorders, and TNF-α a pivotal neuroinflammatory driver.

NEW HYPOTHESIS

AD-associated chronic neuroinflammation directly drives progressive synaptic/neuronal loss and cognitive decline. Pharmacologically mitigating microglial/astrocyte activation without altering Aβ generation will define the role of neuroinflammation in AD progression.

MAJOR CHALLENGES

Difficulty of TNF-α-lowering compounds reaching brain, and identification of a therapeutic-time window to preserve the beneficial role of neuroinflammatory processes.

LINKAGE TO OTHER MAJOR THEORIES

Microglia/astroglia are heavily implicated in maintenance of synaptic plasticity/function in healthy brain and are disrupted by Aβ. Mitigation of chronic gliosis can restore synaptic homeostasis/cognitive function.

Activity of a Novel Anti-Inflammatory Agent F-3,6'-dithiopomalidomide as a Treatment for Traumatic Brain Injury

Traumatic brain injury (TBI) is a major risk factor for several neurodegenerative disorders, including Parkinson's disease (PD) and Alzheimer's disease (AD). Neuroinflammation is a cause of later secondary cell death following TBI, has the potential to aggravate the initial impact, and provides a therapeutic target, albeit that has failed to translate into clinical trial success. Thalidomide-like compounds have neuroinflammation reduction properties across cellular and animal models of TBI and neurodegenerative disorders. They lower the generation of proinflammatory cytokines, particularly TNF-α which is pivotal in microglial cell activation. Unfortunately, thalidomide-like drugs possess adverse effects in humans before achieving anti-inflammatory drug levels. We developed F-3,6'-dithiopomalidomide (F-3,6'-DP) as a novel thalidomide-like compound to ameliorate inflammation. F-3,6'-DP binds to cereblon but does not efficiently trigger the degradation of the transcription factors (SALL4, Ikaros, and Aiolos) associated with the teratogenic and anti-proliferative responses of thalidomide-like drugs. We utilized a phenotypic drug discovery approach that employed cellular and animal models in the selection and development of F-3,6'-DP. F-3,6'-DP significantly mitigated LPS-induced inflammatory markers in RAW 264.7 cells, and lowered proinflammatory cytokine/chemokine levels in the plasma and brain of rats challenged with systemic LPS. We subsequently examined immunohistochemical, biochemical, and behavioral measures following controlled cortical impact (CCI) in mice, a model of moderate TBI known to induce inflammation. F-3,6'-DP decreased CCI-induced neuroinflammation, neuronal loss, and behavioral deficits when administered after TBI. F-3,6'-DP represents a novel class of thalidomide-like drugs that do not lower classical cereblon-associated transcription factors but retain anti-inflammatory actions and possess efficacy in the treatment of TBI and potentially longer-term neurodegenerative disorders.

Nanocrystals as an effective strategy to improve Pomalidomide bioavailability in rodent

Pomalidomide (POM) is an FDA-approved immunomodulatory imide drug (IMiDs) an it is effectively used in the treatment of multiple myeloma. IMiDs are analogs of the drug thalidomide and they have been repurposed for the treatment of several diseases such as psoriatic arthritis and Kaposi Sarcoma. In recent years, IMiDs have been also evaluated as a new treatment for neurological disorders with an inflammatory and neuroinflammatory component. POM draws particular interest for its potent anti-TNF-α activity at significantly lower concentrations than the parent compound thalidomide. However, POM's low water solubility underpins its low gastrointestinal permeability resulting in irregular and poor absorption. The purpose of this work was to prepare a POM nanocrystal-based formulation that could efficiently improve POM's plasma and brain concentration after intraperitoneal injection. POM nanocrystals prepared as a nanosuspension by the media milling method showed a mean diameter of 219 nm and a polydispersity index of 0.21. POM's nanocrystal solubility value (22.97 µg/mL) in phosphate buffer was about 1.58 folds higher than the POM raw powder. Finally, in vivo studies conducted in adult Male Sprague-Dawley rats indicated that POM nanocrystal ensured higher and longer-lasting drug levels in plasma and brain when compared with POM coarse suspension.

Anatomy and development of the pectoral fin vascular network in the zebrafish

The pectoral fins of teleost fish are analogous structures to human forelimbs, and the developmental mechanisms directing their initial growth and patterning are conserved between fish and tetrapods. The forelimb vasculature is crucial for limb function, and it appears to play important roles during development by promoting development of other limb structures, but the steps leading to its formation are poorly understood. In this study, we use high-resolution imaging to document the stepwise assembly of the zebrafish pectoral fin vasculature. We show that fin vascular network formation is a stereotyped, choreographed process that begins with the growth of an initial vascular loop around the pectoral fin. This loop connects to the dorsal aorta to initiate pectoral vascular circulation. Pectoral fin vascular development continues with concurrent formation of three elaborate vascular plexuses, one in the distal fin that develops into the fin-ray vasculature and two near the base of the fin in association with the developing fin musculature. Our findings detail a complex, yet highly choreographed, series of steps involved in the development of a complete, functional, organ-specific vascular network.

Development of Photolenalidomide for Cellular Target Identification

The thalidomide analogue lenalidomide (Len) is a clinical therapeutic that alters the substrate engagement of cereblon (CRBN), a substrate receptor for the CRL4 E3 ubiquitin ligase. Here, we report the development of photolenalidomide (pLen), a Len probe with a photoaffinity label and enrichment handle, designed for target identification by chemical proteomics. pLen preserves the substrate degradation profile, phenotypic antiproliferative and immunomodulatory properties of Len, and enhances interactions with the thalidomide-binding domain of CRBN, as revealed by binding site mapping and molecular modeling. Using pLen, we captured the known targets IKZF1 and CRBN from multiple myeloma MM.1S cells and further identified a new target, eukaryotic translation initiation factor 3 subunit i (eIF3i), from HEK293T cells. eIF3i is directly labeled by pLen and forms a ternary complex with CRBN in the presence of Len across several epithelial cell lines but is itself not ubiquitylated or degraded. These data point to the existence of a broader array of targets induced by ligands to CRBN that may or may not be degraded, which can be identified by the highly translatable application of pLen to additional biological systems.

Repurposing Pomalidomide as a Neuroprotective Drug: Efficacy in an Alpha-Synuclein-Based Model of Parkinson's Disease

Marketed drugs for Parkinson's disease (PD) treat disease motor symptoms but are ineffective in stopping or slowing disease progression. In the quest of novel pharmacological approaches that may target disease progression, drug-repurposing provides a strategy to accelerate the preclinical and clinical testing of drugs already approved for other medical indications. Here, we targeted the inflammatory component of PD pathology, by testing for the first time the disease-modifying properties of the immunomodulatory imide drug (IMiD) pomalidomide in a translational rat model of PD neuropathology based on the intranigral bilateral infusion of toxic preformed oligomers of human α-synuclein (H-αSynOs). The neuroprotective effect of pomalidomide (20 mg/kg; i.p. three times/week 48 h apart) was tested in the first stage of disease progression by means of a chronic two-month administration, starting 1 month after H-αSynOs infusion, when an already ongoing neuroinflammation is observed. The intracerebral infusion of H-αSynOs induced an impairment in motor and coordination performance that was fully rescued by pomalidomide, as assessed via a battery of motor tests three months after infusion. Moreover, H-αSynOs-infused rats displayed a 40-45% cell loss within the bilateral substantia nigra, as measured by stereological counting of TH + and Nissl-stained neurons, that was largely abolished by pomalidomide. The inflammatory response to H-αSynOs infusion and the pomalidomide treatment was evaluated both in CNS affected areas and peripherally in the serum. A reactive microgliosis, measured as the volume occupied by the microglial marker Iba-1, was present in the substantia nigra three months after H-αSynOs infusion as well as after H-αSynOs plus pomalidomide treatment. However, microglia differed for their phenotype among experimental groups. After H-αSynOs infusion, microglia displayed a proinflammatory profile, producing a large amount of the proinflammatory cytokine TNF-α. In contrast, pomalidomide inhibited the TNF-α overproduction and elevated the anti-inflammatory cytokine IL-10. Moreover, the H-αSynOs infusion induced a systemic inflammation with overproduction of serum proinflammatory cytokines and chemokines, that was largely mitigated by pomalidomide. Results provide evidence of the disease modifying potential of pomalidomide in a neuropathological rodent model of PD and support the repurposing of this drug for clinical testing in PD patients.

From the Farm to the Lab: How Chicken Embryos Contribute to the Field of Teratology

Congenital anomalies and its causes, particularly, by external factors are the aim of the field called teratology. The external factors studied by teratology are known as teratogens and can be biological or environmental factors for example, chemicals, medications, recreational drugs, environmental pollutants, physical agents (e.g., X-rays and maternal hyperthermia) and maternal metabolic conditions. Proving the teratogenicity of a factor is a difficult task requiring epidemiology studies as well as experimental teratology evidence from the use of animal models, one of which is the chicken embryo. This model in particular has the advantage of being able to follow development live and in vivo, with rapid development hatching around 21 days, is cheap and easy to manipulate and to observe development. All this allows the chicken embryo to be used in drug screening studies, teratogenic evaluation and studies of mechanisms of teratogenicity. The chicken embryo shares morphological, biochemical and genetic similarities with humans as well as mammalian species, making them ideal to ascertain the actions of teratogens, as well as screen drugs to test for their safety. Pre-clinical trials for new drugs are carried out in rodents and rabbits, however, chicken embryos have been used to screen new compounds or analogs of thalidomide as well as to investigate how some drugs can lead to congenital malformations. Indeed, the chicken embryo has proved valuable in understanding how many congenital anomalies, seen in humans, arise following teratogen exposure. The aim of this review is to highlight the role of the chicken embryo as an experimental model for studies in teratology, exploring its use in drug screening studies, phenotypic evaluation and studies of teratogenic mechanisms of action. Here, we discuss many known teratogens, that have been evaluated using the chicken embryo model including some medicines, such as, thalidomide, valproic acid; recreational drugs including alcohol; environmental influences, such as viruses, specifically ZIKV, which is a newly discovered human teratogen. In addition, we discuss how the chicken embryo has provided insight on the mechanisms of teratogenesis of many compounds and also how this impact on drug safety.

Comparative Genomics Identifies Putative Interspecies Mechanisms Underlying Crbn-Sall4-Linked Thalidomide Embryopathy

The identification of thalidomide–Cereblon-induced SALL4 degradation has brought new understanding for thalidomide embryopathy (TE) differences across species. Some questions, however, regarding species variability, still remain. The aim of this study was to detect sequence divergences between species, affected or not by TE, and to evaluate the regulated gene co-expression in a murine model. Here, we performed a comparative analysis of proteins experimentally established as affected by thalidomide exposure, evaluating 14 species. The comparative analysis, regarding synteny, neighborhood, and protein conservation, was performed in 42 selected genes. Differential co-expression analysis was performed, using a publicly available assay, GSE61306, which evaluated mouse embryonic stem cells (mESC) exposed to thalidomide. The comparative analyses evidenced 20 genes in the upstream neighborhood of NOS3, which are different between the species who develop, or not, the classic TE phenotype. Considering protein sequence alignments, RECQL4, SALL4, CDH5, KDR, and NOS2 proteins had the biggest number of variants reported in unaffected species. In co-expression analysis, Crbn was a gene identified as a driver of the co-expression of other genes implicated in genetic, non-teratogenic, limb reduction defects (LRD), such as Tbx5, Esco2, Recql4, and Sall4; Crbn and Sall4 were shown to have a moderate co-expression correlation, which is affected after thalidomide exposure. Hence, even though the classic TE phenotype is not identified in mice, a deregulatory Crbn-induced mechanism is suggested in this animal. Functional studies are necessary, especially evaluating the genes responsible for LRD syndromes and their interaction with thalidomide–Cereblon.

Repurposing Immunomodulatory Imide Drugs (IMiDs) in Neuropsychiatric and Neurodegenerative Disorders

Neuroinflammation represents a common trait in the pathology and progression of the major psychiatric and neurodegenerative disorders. Neuropsychiatric disorders have emerged as a global crisis, affecting 1 in 4 people, while neurological disorders are the second leading cause of death in the elderly population worldwide (WHO, 2001; GBD 2016 Neurology Collaborators, 2019). However, there remains an immense deficit in availability of effective drug treatments for most neurological disorders. In fact, for disorders such as depression, placebos and behavioral therapies have equal effectiveness as antidepressants. For neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease, drugs that can prevent, slow, or cure the disease have yet to be found. Several non-traditional avenues of drug target identification have emerged with ongoing neurological disease research to meet the need for novel and efficacious treatments. Of these novel avenues is that of neuroinflammation, which has been found to be involved in the progression and pathology of many of the leading neurological disorders. Neuroinflammation is characterized by glial inflammatory factors in certain stages of neurological disorders. Although the meta-analyses have provided evidence of genetic/proteomic upregulation of inflammatory factors in certain stages of neurological disorders. Although the mechanisms underpinning the connections between neuroinflammation and neurological disorders are unclear, and meta-analysis results have shown high sensitivity to factors such as disorder severity and sample type, there is significant evidence of neuroinflammation associations across neurological disorders. In this review, we summarize the role of neuroinflammation in psychiatric disorders such as major depressive disorder, generalized anxiety disorder, post-traumatic stress disorder, and bipolar disorder, as well as in neurodegenerative disorders, such as Parkinson's disease and Alzheimer's disease, and introduce current research on the potential of immunomodulatory imide drugs (IMiDs) as a new treatment strategy for these disorders.

Thalidomide and its metabolite 5-hydroxythalidomide induce teratogenicity via the cereblon neosubstrate PLZF

Thalidomide causes teratogenic effects by inducing protein degradation via cereblon (CRBN)‐containing ubiquitin ligase and modification of its substrate specificity. Human P450 cytochromes convert thalidomide into two monohydroxylated metabolites that are considered to contribute to thalidomide effects, through mechanisms that remain unclear. Here, we report that promyelocytic leukaemia zinc finger (PLZF)/ZBTB16 is a CRBN target protein whose degradation is involved in thalidomide‐ and 5‐hydroxythalidomide‐induced teratogenicity. Using a human transcription factor protein array produced in a wheat cell‐free protein synthesis system, PLZF was identified as a thalidomide‐dependent CRBN substrate. PLZF is degraded by the ubiquitin ligase CRL4^CRBN in complex with thalidomide, its derivatives or 5‐hydroxythalidomide in a manner dependent on the conserved first and third zinc finger domains of PLZF. Surprisingly, thalidomide and 5‐hydroxythalidomide confer distinctly different substrate specificities to mouse and chicken CRBN, and both compounds cause teratogenic phenotypes in chicken embryos. Consistently, knockdown of Plzf induces short bone formation in chicken limbs. Most importantly, degradation of PLZF protein, but not of the known thalidomide‐dependent CRBN substrate SALL4, was induced by thalidomide or 5‐hydroxythalidomide treatment in chicken embryos. Furthermore, PLZF overexpression partially rescued the thalidomide‐induced phenotypes. Our findings implicate PLZF as an important thalidomide‐induced CRBN neosubstrate involved in thalidomide teratogenicity.

A cross-platform approach to characterize and screen potential neurovascular unit toxicants

Development of the neurovascular unit (NVU) is a complex, multistage process that requires orchestrated cell signaling mechanisms across several cell types and ultimately results in formation of the blood-brain barrier. Typical high-throughput screening (HTS) assays investigate single biochemical or single cell responses following chemical insult. As the NVU comprises multiple cell types interacting at various stages of development, a methodology combining high-throughput results across pertinent cell-based assays is needed to investigate potential chemical-induced disruption to the development of this complex cell system. To this end, we implemented a novel method for screening putative NVU disruptors across diverse assay platforms to predict chemical perturbation of the developing NVU. HTS assay results measuring chemical-induced perturbations to cellular key events across angiogenic and neurogenic outcomes in vitro were combined to create a cell-based prioritization of NVU hazard. Chemicals were grouped according to similar modes of action to train a logistic regression literature model on a training set of 38 chemicals. This model utilizes the chemical-specific pairwise mutual information score for PubMed MeSH annotations to represent a quantitative measure of previously published results. Taken together, this study presents a methodology to investigate NVU developmental hazard using cell-based HTS assays and literature evidence to prioritize screening of putative NVU disruptors towards a knowledge-driven characterization of neurovascular developmental toxicity. The results from these screening efforts demonstrate that chemicals representing a range of putative vascular disrupting compound (pVDC) scores can also produce effects on neurogenic outcomes and characterizes possible modes of action for disrupting the developing NVU.

Role of cereblon in angiogenesis and in mediating the antiangiogenic activity of immunomodulatory drugs

Cereblon (CRBN) is a substrate recruiter element of the E3 cullin 4-RING ubiquitin ligase complex, and a binding target of immunomodulatory agents (IMiDs). CRBN is responsible for the pleiotropic effects of IMiDs, yet its function in angiogenesis and in mediating the antiangiogenic effects of IMiDs remains unclear. We investigated the role of CRBN in the angiogenic process and in propagating the antiangiogenic effects of IMiDs in vitro. siRNA-mediated CRBN knock down in human endothelial cells (HUVEC and HMVEC-L), did not affect endothelial cell proliferation, migration, or tube formation. Using CRBN-deficient mice, we further demonstrated that microvessal formation can occur independently of cereblon in the ex vivo mouse aortic ring model. The cereblon E3 ubiquitin ligase complex can recruit endothelial cell-specific factors, AGO2 (associated with angiogenesis), and SALL4 (associated with embryogenesis/angiogenesis), for ubiquitin-mediated degradation. Knockdown of CRBN caused a corresponding increase in AGO2 and SALL4 protein expression and IMiD treatment was able to rescue the siCRBN effect to increase the CRBN expression. These findings suggest one potential mechanism of action that likely involves a tightly coordinated regulation of CRBN with endothelial cell targets and highlight the need to further elucidate the mechanism(s), which could include cereblon-independent pathways, through which IMiDs exert their antiangiogenic effects.

Neuroprotection by the Immunomodulatory Drug Pomalidomide in the Drosophila LRRK2WD40 Genetic Model of Parkinson's Disease

The search for new disease-modifying drugs for Parkinson's disease (PD) is a slow and highly expensive process, and the repurposing of drugs already approved for different medical indications is becoming a compelling alternative option for researchers. Genetic variables represent a predisposing factor to the disease and mutations in leucine-rich repeat kinase 2 (LRRK2) locus have been correlated to late-onset autosomal-dominant PD. The common fruit fly Drosophila melanogaster carrying the mutation LRRK2 loss-of-function in the WD40 domain (LRRK2^WD40), is a simple in vivo model of PD and is a valid tool to first evaluate novel therapeutic approaches to the disease. Recent studies have suggested a neuroprotective activity of immunomodulatory agents in PD models. Here the immunomodulatory drug Pomalidomide (POM), a Thalidomide derivative, was examined in the Drosophila LRRK2^WD40 genetic model of PD. Mutant and wild type flies received increasing POM doses (1, 0.5, 0.25 mM) through their diet from day 1 post eclosion, until postnatal day (PN) 7 or 14, when POM's actions were evaluated by quantifying changes in climbing behavior as a measure of motor performance, the number of brain dopaminergic neurons and T-bars, mitochondria integrity. LRRK2^WD40 flies displayed a spontaneous age-related impairment of climbing activity, and POM significantly and dose-dependently improved climbing performance both at PN 7 and PN 14. LRRK2^WD40 fly motor disability was underpinned by a progressive loss of dopaminergic neurons in posterior clusters of the protocerebrum, which are involved in the control of locomotion, by a low number of T-bars density in the presynaptic bouton active zones. POM treatment fully rescued the cell loss in all posterior clusters at PN 7 and PN 14 and significantly increased the T-bars density. Moreover, several damaged mitochondria with dilated cristae were observed in LRRK2^WD40 flies treated with vehicle but not following POM. This study demonstrates the neuroprotective activity of the immunomodulatory agent POM in a genetic model of PD. POM is an FDA-approved clinically available and well-tolerated drug used for the treatment of multiple myeloma. If further validated in mammalian models of PD, POM could rapidly be clinically tested in humans.

Pomalidomide Reduces Ischemic Brain Injury in Rodents

Stroke is a leading cause of death and severe disability worldwide. After cerebral ischemia, inflammation plays a central role in the development of permanent neurological damage. Reactive oxygen species (ROS) are involved in the mechanism of post-ischemic inflammation. The activation of several inflammatory enzymes produces ROS, which subsequently suppress mitochondrial activity, leading to further tissue damage. Pomalidomide (POM) is a clinically available immunomodulatory and anti-inflammatory agent. Prior cellular studies demonstrate that POM can mitigate oxidative stress and lower levels of pro-inflammatory cytokines, particularly TNF-α, which plays a prominent role in ischemic stroke-induced brain damage and functional deficits. To evaluate the potential value of POM in cerebral ischemia, POM was initially administered to transgenic mice chronically over-expressing TNF-α surfactant protein (SP)-C promoter (SP-C/TNF-α mice) to assess whether systemically administered drug could lower systemic TNF-α level. POM significantly lowered serum levels of TNF-α and IL-5. Pharmacokinetic studies were then undertaken in mice to evaluate brain POM levels following systemic drug administration. POM possessed a brain/plasma concentration ratio of 0.71. Finally, rats were subjected to transient middle cerebral artery occlusion (MCAo) for 60 min, and subsequently treated with POM 30 min thereafter to evaluate action on cerebral ischemia. POM reduced the cerebral infarct volume in MCAo-challenged rats and improved motor activity, as evaluated by the elevated body swing test. POM’s neuroprotective actions on ischemic injury represent a potential therapeutic approach for ischemic brain damage and related disorders, and warrant further evaluation.

Thalidomide and Its Analogs Differentially Target Fibroblast Growth Factor Receptors: Thalidomide Suppresses FGFR Gene Expression while Pomalidomide Dampens FGFR2 Activity

Thalidomide is an infamous teratogen and it is continuously being explored for its anticancer properties. Fibroblast growth factor receptors (FGFRs) are implicated in embryo development and cancer pathophysiology. With striking similarities observed between FGFR implicated conditions and thalidomide embryopathy, we hypothesized thalidomide targets FGFRs. We utilized three different cell lines and chicken embryo model to investigate the effects of thalidomide and analogs on FGFR expression. We performed molecular docking, KINOMEscan analysis, and kinase activity assays to study the drug-protein interactions. The expression of FGFR1 and FGFR2 was differentially regulated by all the three drugs in cells as well as in developing organs. Transcriptome analysis of thalidomide-treated chick embryo strongly suggests the modulation of FGFR signaling and key transcription factors. Corroboration with previous studies suggests that thalidomide might affect FGFR expression through the transcription factor, E2F1. At the protein level, molecular docking predicted all three analogs to interact with lysine residue at 517th and 508th positions of FGFR2 and FGFR3, respectively. This lysine coordinates the ATP binding site of FGFR, thus hinting at the possible perturbation of FGFR activity by thalidomide. Kinome analysis revealed that kinase activities of FGFR2 and FGFR3 (G697C) reduced by 31% and 65%, respectively, in the presence of 10 μM thalidomide. Further, we checked and confirmed that the analogs inhibited the FGFR2 kinase activity in a dose-dependent manner. This study suggests that FGFRs could be potential targets of thalidomide and the two analogs, and also endorses the link between the teratogenicity and antitumor activities of the drugs.

Pomalidomide Ameliorates H₂O₂-Induced Oxidative Stress Injury and Cell Death in Rat Primary Cortical Neuronal Cultures by Inducing Anti-Oxidative and Anti-Apoptosis Effects

Due to its high oxygen demand and abundance of peroxidation-susceptible lipid cells, the brain is particularly vulnerable to oxidative stress. Induced by a redox state imbalance involving either excessive generation of reactive oxygen species (ROS) or dysfunction of the antioxidant system, oxidative stress plays a central role in a common pathophysiology that underpins neuronal cell death in acute neurological disorders epitomized by stroke and chronic ones such as Alzheimer’s disease. After cerebral ischemia, for example, inflammation bears a key responsibility in the development of permanent neurological damage. ROS are involved in the mechanism of post-ischemic inflammation. The activation of several inflammatory enzymes produces ROS, which subsequently suppress mitochondrial activity, leading to further tissue damage. Pomalidomide (POM) is a clinically available immunomodulatory and anti-inflammatory agent. Using H₂O₂-treated rat primary cortical neuronal cultures, we found POM displayed neuroprotective effects against oxidative stress and cell death that associated with changes in the nuclear factor erythroid derived 2/superoxide dismutase 2/catalase signaling pathway. POM also suppressed nuclear factor kappa-light-chain-enhancer (NF-κB) levels and significantly mitigated cortical neuronal apoptosis by regulating Bax, Cytochrome c and Poly (ADP-ribose) polymerase. In summary, POM exerted neuroprotective effects via its anti-oxidative and anti-inflammatory actions against H₂O₂-induced injury. POM consequently represents a potential therapeutic agent against brain damage and related disorders and warrants further evaluation.

Design, synthesis and biological assessment of N-adamantyl, substituted adamantyl and noradamantyl phthalimidines for nitrite, TNF-α and angiogenesis inhibitory activities

A library of 15 novel and heretofore uncharacterized adamantyl and noradamantyl phthalimidines was synthesized and evaluated for neuroprotective and anti-angiogenic properties. Phthalimidine treatment in LPS-challenged cells effected reductions in levels of secreted TNF-α and nitrite relative to basal amounts. The primary SAR suggests nitration of adamantyl phthalimidines has marginal effect on TNF-α activity but promotes anti-nitrite activity; thioamide congeners retain anti-nitrite activity but are less effective reducing TNF-α. Site-specific nitration and thioamidation provided phthalimidine 24, effecting an 88.5% drop in nitrite concurrent with only a 4% drop in TNF-α. Notable anti-angiogenesis activity was observed for 20, 21 and 22.

The Primodos components Norethisterone acetate and Ethinyl estradiol induce developmental abnormalities in zebrafish embryos

Primodos was a hormone pregnancy test used between 1958-1978 that has been implicated with causing a range of birth defects ever since. Though Primodos is no longer used, it's components, Norethisterone acetate and Ethinyl estradiol, are used in other medications today including treatments for endometriosis and contraceptives. However, whether Primodos caused birth defects or not remains controversial, and has been little investigated. Here we used the developing zebrafish embryo, a human cell-line and mouse retinal explants to investigate the actions of the components of Primodos upon embryonic and tissue development. We show that Norethisterone acetate and Ethinyl estradiol cause embryonic damage in a dose and time responsive manner. The damage occurs rapidly after drug exposure, affecting multiple organ systems. Moreover, we found that the Norethisterone acetate and Ethinyl estradiol mixture can affect nerve outgrowth and blood vessel patterning directly and accumulates in the forming embryo for at least 24 hrs. These data demonstrate that Norethisterone acetate and Ethinyl estradiol are potentially teratogenic, depending on dose and embryonic stage of development in the zebrafish. Further work in mammalian model species are now required to build on these findings and determine if placental embryos also are affected by synthetic sex hormones and their mechanisms of action.

In vivo screening and discovery of novel candidate thalidomide analogs in the zebrafish embryo and chicken embryo model systems

Thalidomide, a drug known for its teratogenic side-effects, is used successfully to treat a variety of clinical conditions including leprosy and multiple myeloma. Intense efforts are underway to synthesize and identify safer, clinically relevant analogs. Here, we conduct a preliminary in vivo screen of a library of new thalidomide analogs to determine which agents demonstrate activity, and describe a cohort of compounds with anti-angiogenic properties, anti-inflammatory properties and some compounds which exhibited both. The combination of the in vivo zebrafish and chicken embryo model systems allows for the accelerated discovery of new, potential therapies for cancerous and inflammatory conditions.

CPS49-induced neurotoxicity does not cause limb patterning anomalies in developing chicken embryos

Thalidomide notoriously caused severe birth defects, particularly to the limbs, in those exposed in utero following maternal use of the drug to treat morning sickness. How the drug caused these birth defects remains unclear. Many theories have been proposed including actions on the forming blood vessels. However, thalidomide survivors also have altered nerve patterns and the drug is known for its neurotoxic actions in adults following prolonged use. We have previously shown that CPS49, an anti-angiogenic analog of thalidomide, causes a range of limb malformations in a time-sensitive manner in chicken embryos. Here we investigated whether CPS49 also is neurotoxic and whether effects on nerve development impact upon limb development. We found that CPS49 is neurotoxic, just like thalidomide, and can cause some neuronal loss late developing chicken limbs, but only when the limb is already innervated. However, CPS49 exposure does not cause defects in limb size when added to late developing chicken limbs. In contrast, in early limb buds which are not innervated, CPS49 exposure affects limb area significantly. To investigate in more detail the role of neurotoxicity and its impact on chicken limb development we inhibited nerve innervation at a range of developmental timepoints through using β-bungarotoxin. We found that neuronal inhibition or ablation before, during or after limb outgrowth and innervation does not result in obvious limb cartilage patterning or number changes. We conclude that while CPS49 is neurotoxic, given the late innervation of the developing limb, and that neuronal inhibition/ablation throughout limb development does not cause similar limb patterning anomalies to those seen in thalidomide survivors, nerve defects are not the primary underlying cause of the severe limb patterning defects induced by CPS49/thalidomide.

Vertebrate embryos as tools for anti-angiogenic drug screening and function

The development of new angiogenic inhibitors highlights a need for robust screening assays that adequately capture the complexity of vessel formation, and allow for the quantitative evaluation of the teratogenicity of new anti-angiogenic agents. This review discusses the use of screening assays in vertebrate embryos, specifically focusing upon chicken and zebrafish embryos, for the detection of anti-angiogenic agents.

A Brighter Side to Thalidomide: Its Potential Use in Immunological Disorders

Thalidomide and its derivatives are immunomodulatory drugs (IMiDs) known for their sedative, teratogenic, anti-angiogenic, and anti-inflammatory properties. Commonly used in the treatment of cancers such as multiple myeloma and myelodysplastic syndrome (MDS), IMiDs have also been used in the treatment of an inflammatory skin pathology associated with Hansen's disease/leprosy. They have also shown promise in the treatment of autoimmune disorders including systemic lupus erythmatosus (SLE) and inflammatory bowel disease (IBD). Recent structural and experimental observations have revolutionized our understanding of these properties by revealing the fundamental molecular events underpinning IMiD activity. We review these findings, their relevance to IMiD therapy in immunological disorders, and discuss how further research might unlock the vast clinical potential of these compounds.

A new mammalian model system for thalidomide teratogenesis: Monodelphis domestica

From 1957 to 1962, thalidomide caused birth defects in >10,000 children. While the drug was pulled from the market, thalidomide is currently prescribed to treat conditions including leprosy. As a result, a new generation of babies with thalidomide defects is being born in the developing world. This represents a serious problem, as the mechanisms by which thalidomide disrupts development remain unresolved. This lack of resolution is due, in part, to the absence of an appropriate mammalian model for thalidomide teratogenesis. We test the hypothesis that opossum (Monodelphis domestica) is well suited to model human thalidomide defects. Results suggest that opossum embryos exposed to thalidomide display a range of phenotypes (e.g., heart, craniofacial, limb defects) and penetrance similar to humans. Furthermore, all opossums with thalidomide defects exhibit vascular disruptions. Results therefore support the hypotheses that opossums make a good mammalian model for thalidomide teratogenesis, and that thalidomide can severely disrupt angiogenesis in mammals.

A Novel Green Synthesis of Thalidomide and Analogs

Thalidomide and its derivatives are currently under investigation for their antiangiogenic, immunomodulative, and anticancer properties. Current methods used to synthesize these compounds involve multiple steps and extensive workup procedures. Described herein is an efficient microwave irradiation green synthesis method that allows preparation of thalidomide and its analogs in a one-pot multicomponent synthesis system. The multicomponent synthesis system developed involves an array of cyclic anhydrides, glutamic acid, and ammonium chloride in the presence of catalytic amounts of 4-N,N-dimethylaminopyridine (DMAP) to produce thalidomide and structurally related compounds within minutes in good isolated yields.

The impact of thalidomide use in birth defects in Brazil

Although the thalidomide tragedy occurred more than 50 years ago, the medication is still being used worldwide for different reasons, and several aspects regarding its teratogenicity remain unsolved. Despite the strict regulation implemented, new cases of thalidomide embryopathy (TE) are still being registered in Brazil. Furthermore, the molecular processes that lead to malformations when the embryo is exposed to thalidomide have not yet been fully identified. In this article, we perform a critical analysis of thalidomide's history in Brazil, highlighting aspects of the occurrence of TE over the decades. Finally, we present the main perspectives and challenges for ongoing surveillance and prevention of TE in Brazil. The effective control of dispensing thalidomide, especially in areas where leprosy is endemic, is one of the most important and challenging points. Furthermore, the emergence of thalidomide analogues is fast approaching, and their availability would pose additional concerns. The understanding of the molecular mechanisms and targets of thalidomide in both experimental and human models is essential for generating new insights into teratogenic mechanisms, so that safer thalidomide analogues can be developed.

Reference compounds for alternative test methods to indicate developmental neurotoxicity (DNT) potential of chemicals: example lists and criteria for their selection and use

There is a paucity of information concerning the developmental neurotoxicity (DNT) hazard posed by industrial and environmental chemicals. New testing approaches will most likely be based on batteries of alternative and complementary (non-animal) tests. As DNT is assumed to result from the modulation of fundamental neurodevelopmental processes (such as neuronal differentiation, precursor cell migration or neuronal network formation) by chemicals, the first generation of alternative DNT tests target these processes. The advantage of such types of assays is that they capture toxicants with multiple targets and modes-of-action. Moreover, the processes modelled by the assays can be linked to toxicity endophenotypes, i.e. alterations in neural connectivity that form the basis for neurofunctional deficits in man. The authors of this review convened in a workshop to define criteria for the selection of positive/negative controls, to prepare recommendations on their use, and to initiate the setup of a directory of reference chemicals. For initial technical optimization of tests, a set of >50 endpoint-specific control compounds was identified. For further test development, an additional “test” set of 33 chemicals considered to act directly as bona fide DNT toxicants is proposed, and each chemical is annotated to the extent it fulfills these criteria. A tabular compilation of the original literature used to select the test set chemicals provides information on statistical procedures, and toxic/non-toxic doses (both for pups and dams). Suggestions are provided on how to use the >100 compounds (including negative controls) compiled here to address specificity, adversity and use of alternative test systems.

Shared mechanism of teratogenicity of anti-angiogenic drugs identified in the chicken embryo model

Angiogenesis, the formation of new blood vessels, is essential for tumor growth, stabilization and progression. Angiogenesis inhibitors are now widely used in the clinic; however, there are relatively few published studies on the mechanism of their presumed teratogenic effects. To address this issue, we screened a variety of angiogenesis inhibitors in developing zebrafish and chicken embryo models to assess for developmental defects and potential teratogenic effects. We confirmed previous reports that sunitinib, sorafenib and TNP-470 are teratogenic and demonstrate that axitinib, pazopanib, vandetanib, and everolimus are also teratogens in these models. A dose response study identified the drugs inhibit HUVEC cell proliferation in vitro, and also target the developing blood vessels of embryos in vivo. This provides further evidence for the potential risk of fetal toxicity when using these drugs in a clinical setting, and emphasizes the importance of the development and maintenance of the vasculature in the embryo. We conclude that angiogenesis inhibitors, regardless of the molecular target, are teratogenic when exposed to chicken embryos.

Mutations in STN1 cause Coats plus syndrome and are associated with genomic and telomere defects

The analysis of individuals with telomere defects may shed light on the delicate interplay of factors controlling genome stability, premature aging, and cancer. We herein describe two Coats plus patients with telomere and genomic defects; both harbor distinct, novel mutations in STN1, a member of the human CTC1-STN1-TEN1 (CST) complex, thus linking this gene for the first time to a human telomeropathy. We characterized the patients' phenotype, recapitulated it in a zebrafish model and rescued cellular and clinical aspects by the ectopic expression of wild-type STN1 or by thalidomide treatment. Interestingly, a significant lengthy control of the gastrointestinal bleeding in one of our patients was achieved by thalidomide treatment, exemplifying a successful bed-to-bench-and-back approach.

Pomalidomide mitigates neuronal loss, neuroinflammation, and behavioral impairments induced by traumatic brain injury in rat

BACKGROUND

Traumatic brain injury (TBI) is a global health concern that typically causes emotional disturbances and cognitive dysfunction. Secondary pathologies following TBI may be associated with chronic neurodegenerative disorders and an enhanced likelihood of developing dementia-like disease in later life. There are currently no approved drugs for mitigating the acute or chronic effects of TBI.

METHODS

The effects of the drug pomalidomide (Pom), an FDA-approved immunomodulatory agent, were evaluated in a rat model of moderate to severe TBI induced by controlled cortical impact. Post-TBI intravenous administration of Pom (0.5 mg/kg at 5 or 7 h and 0.1 mg/kg at 5 h) was evaluated on functional and histological measures that included motor function, fine more coordination, somatosensory function, lesion volume, cortical neurodegeneration, neuronal apoptosis, and the induction of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6).

RESULTS

Pom 0.5 mg/kg administration at 5 h, but not at 7 h post-TBI, significantly mitigated the TBI-induced injury volume and functional impairments, neurodegeneration, neuronal apoptosis, and cytokine mRNA and protein induction. To evaluate underlying mechanisms, the actions of Pom on neuronal survival, microglial activation, and the induction of TNF-α were assessed in mixed cortical cultures following a glutamate challenge. Pom dose-dependently ameliorated glutamate-mediated cytotoxic effects on cell viability and reduced microglial cell activation, significantly attenuating the induction of TNF-α.

CONCLUSIONS

Post-injury treatment with a single Pom dose within 5 h significantly reduced functional impairments in a well-characterized animal model of TBI. Pom decreased the injury lesion volume, augmented neuronal survival, and provided anti-inflammatory properties. These findings strongly support the further evaluation and optimization of Pom for potential use in clinical TBI.

Anticancer Properties of a Novel Class of Tetrafluorinated Thalidomide Analogues

Thalidomide has demonstrated clinical activity in various malignancies affecting immunomodulatory and angiogenic pathways. The development of novel thalidomide analogs with improved efficacy and decreased toxicity is an ongoing research effort. We recently designed and synthesized a new class of compounds, consisting of both tetrafluorinated thalidomide analogues (Gu973 and Gu998) and tetrafluorobenzamides (Gu1029 and Gu992). In this study, we demonstrate the antiangiogenic properties of these newly synthesized compounds. We examined the specific antiangiogenic characteristics in vitro using rat aortic rings with carboxyamidotriazole as a positive control. In addition, further in vitro efficacy was evaluated using human umbilical vein endothelial cells (HUVEC) and PC3 cells treated with 5 and 10 μmol/L doses of each compound. All compounds were seen to reduce microvessel outgrowth in rat aortic rings as well as to inhibit HUVECs to a greater extent, at lower concentrations than previously tested thalidomide analogs. The antiangiogenic properties of the compounds were also examined in vivo in fli1:EGFP zebrafish embryos, where all compounds were seen to inhibit the extent of outgrowth of newly developing blood vessels. In addition, Gu1029 and Gu973 reduced the anti-inflammatory response in mpo:GFP zebrafish embryos, whereas Gu998 and Gu992 showed no difference. The compounds' antitumor effects were also explored in vivo using the human prostate cancer PC3 xenograft model. All four compounds were also screened in vivo in chicken embryos to investigate their teratogenic potential. This study establishes these novel thalidomide analogues as a promising immunomodulatory class with anticancer effects that warrant further development to characterize their mechanisms of action.

Thalidomide-induced teratogenesis: history and mechanisms

Nearly 60 years ago thalidomide was prescribed to treat morning sickness in pregnant women. What followed was the biggest man‐made medical disaster ever, where over 10,000 children were born with a range of severe and debilitating malformations. Despite this, the drug is now used successfully to treat a range of adult conditions, including multiple myeloma and complications of leprosy. Tragically, a new generation of thalidomide damaged children has been identified in Brazil. Yet, how thalidomide caused its devastating effects in the forming embryo remains unclear. However, studies in the past few years have greatly enhanced our understanding of the molecular mechanisms the drug. This review will look at the history of the drug, and the range and type of damage the drug caused, and outline the mechanisms of action the drug uses including recent molecular advances and new findings. Some of the remaining challenges facing thalidomide biologists are also discussed. Birth Defects Research (Part C) 105:140–156, 2015. © 2015 The Authors Birth Defects Research Part C: Embryo Today: Reviews Published by Wiley Periodicals, Inc.

Advancing host-directed therapy for tuberculosis

Improved treatments are needed for nearly all forms of Mycobacterium tuberculosis infection. Adjunctive host-directed therapies have the potential to shorten tuberculosis treatment duration, prevent resistance and reduce lung injury by promoting autophagy, antimicrobial peptide production and other macrophage effector mechanisms, as well as by modifying specific mechanisms that cause lung inflammation and matrix destruction. The range of candidates is broad, including several agents approved for other clinical indications that are ready for evaluation in Phase II clinical trials. The promise of new and existing host-directed therapies that could accelerate response and improve tuberculosis treatment outcomes is discussed in this Opinion article.

Transiently lowering tumor necrosis factor-α synthesis ameliorates neuronal cell loss and cognitive impairments induced by minimal traumatic brain injury in mice

Background

The treatment of traumatic brain injury (TBI) represents an unmet medical need, as no effective pharmacological treatment currently exists. The development of such a treatment requires a fundamental understanding of the pathophysiological mechanisms that underpin the sequelae resulting from TBI, particularly the ensuing neuronal cell death and cognitive impairments. Tumor necrosis factor-alpha (TNF-α) is a cytokine that is a master regulator of systemic and neuroinflammatory processes. TNF-α levels are reported to become rapidly elevated post TBI and, potentially, can lead to secondary neuronal damage.

Methods

To elucidate the role of TNF-α in TBI, particularly as a drug target, the present study evaluated (i) time-dependent TNF-α levels and (ii) markers of apoptosis and gliosis within the brain and related these to behavioral measures of ‘well being’ and cognition in a mouse closed head 50 g weight drop mild TBI (mTBI) model in the presence and absence of post-treatment with an experimental TNF-α synthesis inhibitor, 3,6′-dithiothalidomide.

Results

mTBI elevated brain TNF-α levels, which peaked at 12 h post injury and returned to baseline by 18 h. This was accompanied by a neuronal loss and an increase in astrocyte number (evaluated by neuronal nuclei (NeuN) and glial fibrillary acidic protein (GFAP) immunostaining), as well as an elevation in the apoptotic death marker BH3-interacting domain death agonist (BID) at 72 h. Selective impairments in measures of cognition, evaluated by novel object recognition and passive avoidance paradigms - without changes in well being, were evident at 7 days after injury. A single systemic treatment with the TNF-α synthesis inhibitor 3,6′-dithiothalidomide 1 h post injury prevented the mTBI-induced TNF-α elevation and fully ameliorated the neuronal loss (NeuN), elevations in astrocyte number (GFAP) and BID, and cognitive impairments. Cognitive impairments evident at 7 days after injury were prevented by treatment as late as 12 h post mTBI but were not reversed when treatment was delayed until 18 h.

Conclusions

These results implicate that TNF-α in mTBI induced secondary brain damage and indicate that pharmacologically limiting the generation of TNF-α post mTBI may mitigate such damage, defining a time-dependent window of up to 12 h to achieve this reversal.

Impact of pomalidomide therapy in multiple myeloma: a recent survey

Pomalidomide (Pomalyst(®)) is a synthetic compound derived by modifying the chemical structure of thalidomide to improve its potency and reduce its side effects and third drug in the class of immunomodulatory drugs. Pomalidomide is under global development with Celgene Corporation, was approved by the U.S. Food and Drug Administration on February 8, 2013 to treat patients with relapsed and refractory multiple myeloma (MM) who have received at least two prior therapies including bortezomib and lenalidomide. In October 2009, it has found orphan designation for the treatment of relapsed and refractory MM by the EMA, and on August 2013, marketing authorization has issued in Europe by gaining a positive response. It inhibits myeloma cell growth and angiogenesis directly. Pomalidomide is the latest myeloma cell growth inhibitor to be approved in both USA and EU. The predominant side effects are thrombocytopenia, neuropathy, and deep vein thrombosis. Pomalidomide is also being investigated in patients with amyloidosis, prostate cancer, small cell lung cancer, pancreatic cancer, graft-versus-host disease, and Waldenstrom's macroglobulinemia. This article reviews the available information on pomalidomide with respect to its clinical pharmacology, mechanism of action, pharmacokinetics, pharmacodynamics, metabolism, pre-clinical studies, and clinical trials.

Pomalidomide in the treatment of multiple myeloma and perspectives in other hematological malignancies

SUMMARY 

Pomalidomide is an immunomodulatory drug recently approved by the US FDA and EMA for the treatment of refractory and relapsed multiple myeloma. Pomalidomide appears to be more potent and less toxic than thalidomide and lenalidomide and has proven to be effective in a proportion of patients already exposed and refractory to these agents. The approved combination of pomalidomide and weekly dexamethasone offers clinical benefit to at least one-third of patients with multiple myeloma that have failed both bortezomib and lenolidomide treatment. This review will focus on the preclinical data and clinical experience in this setting. Off-label use of pomalidomide, mainly its combination with other active drugs for multiple myeloma and the role of pomalidomide in other hematologic malignancies still remain to be explored in depth and are discussed briefly.