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.

Selective Extraction of Piceatannol from Passiflora edulis by-Products: Application of HSPs Strategy and Inhibition of Neurodegenerative Enzymes.

Passiflora edulis by-products (PFBP) are a rich source of polyphenols, of which piceatannol has gained special attention recently. However, there are few studies involving environmentally safe methods for obtaining extracts rich in piceatannol. This work aimed to concentrate piceatannol from defatted PFBP (d-PFBP) by means of pressurized liquid extraction (PLE) and conventional extraction, using the bio-based solvents selected with the Hansen solubility parameters approach. The relative energy distance (Ra) between solvent and solute was: Benzyl Alcohol (BnOH) < Ethyl Acetate (EtOAc) < Ethanol (EtOH) < EtOH:H2O. Nonetheless, EtOH presented the best selectivity for piceatannol. Multi-cycle PLE at 110 °C was able to concentrate piceatannol 2.4 times more than conventional extraction. PLE exhibited a dependence on kinetic parameters and temperature, which could be associated with hydrogen bonding forces and the dielectric constant of the solvents. The acetylcholinesterase (AChE) and lipoxygenase (LOX) IC50 were 29.420 µg/mL and 27.682 µg/mL, respectively. The results reinforce the demand for processes to concentrate natural extracts from food by-products.

Insights into Computational Drug Repurposing for Neurodegenerative Disease.

Computational drug repurposing has the ability to remarkably reduce drug development time and cost in an era where these factors are prohibitively high. Several examples of successful repurposed drugs exist in fields such as oncology, diabetes, leprosy, inflammatory bowel disease, among others, however computational drug repurposing in neurodegenerative disease has presented several unique challenges stemming from the lack of validation methods and difficulty in studying heterogenous diseases of aging. Here, we examine existing approaches to computational drug repurposing, including molecular, clinical, and biophysical methods, and propose data sources and methods to advance computational drug repurposing in neurodegenerative disease using Alzheimer's disease as an example.

Mechanisms of regulation and diversification of deubiquitylating enzyme function.

Deubiquitylating (or deubiquitinating) enzymes (DUBs) are proteases that reverse protein ubiquitylation and therefore modulate the outcome of this post-translational modification. DUBs regulate a variety of intracellular processes, including protein turnover, signalling pathways and the DNA damage response. They have also been linked to a number of human diseases, such as cancer, and inflammatory and neurodegenerative disorders. Although we are beginning to better appreciate the role of DUBs in basic cell biology and their importance for human health, there are still many unknowns. Central among these is the conundrum of how the small number of ∼100 DUBs encoded in the human genome is capable of regulating the thousands of ubiquitin modification sites detected in human cells. This Commentary addresses the biological mechanisms employed to modulate and expand the functions of DUBs, and sets directions for future research aimed at elucidating the details of these fascinating processes.This article is part of a Minifocus on Ubiquitin Regulation and Function. For further reading, please see related articles: 'Exploitation of the host cell ubiquitin machinery by microbial effector proteins' by Yi-Han Lin and Matthias P. Machner (J. Cell Sci.130, 1985-1996). 'Cell scientist to watch - Mads Gyrd-Hansen' (J. Cell Sci.130, 1981-1983).

Clinical variables associated with disability in leprosy cases in northeast Brazil.

INTRODUCTION: The clinical outcomes of leprosy include complications such as physical disabilities and deformities that vary according to the degree of impairment of nerve trunks. Knowledge of the factors that lead to the development of these complications is important for disability prevention programs. This study aimed to evaluate clinical factors associated with the occurrence of physical disability in leprosy cases. METHODOLOGY: This was a retrospective study of 2,358 cases of leprosy in Aracaju, northeast Brazil, between 2001 and 2011. Analysis was done using the Chi-square test and logistic regression model. RESULTS: Significant factors associated with disability were found to be male gender, having more than two affected nerves, multibacillary leprosy classification, leprosy reaction, and lepromatous leprosy. The multivariate analysis revealed that the associated factors included having more than two affected nerves, leprosy reaction (adjusted odds ratio [aOR]: 2.02, 95% confidence interval [CI]: 1.36 to 3.01), the multibacillary form (aOR: 2.74, 95% CI: 1.84 to 4.08), and lepromatous leprosy (aOR: 4.87, 95% CI: 2.86 to 16.08). CONCLUSIONS: The number of affected nerves, leprosy reaction, operational classification, and clinical presentation were identified as the main factors associated with the development of disability in leprosy patients.

The armadillo: a model for the neuropathy of leprosy and potentially other neurodegenerative diseases.

Leprosy (also known as Hansen's disease) is an infectious peripheral neurological disorder caused by Mycobacterium leprae that even today leaves millions of individuals worldwide with life-long disabilities. The specific mechanisms by which this bacterium induces nerve injury remain largely unknown, mainly owing to ethical and practical limitations in obtaining affected human nerve samples. In addition to humans, nine-banded armadillos (Dasypus novemcinctus) are the only other natural host of M. leprae, and they develop a systemically disseminated disease with extensive neurological involvement. M. leprae is an obligate intracellular parasite that cannot be cultivated in vitro. Because of the heavy burdens of bacilli they harbor, nine-banded armadillos have become the organism of choice for propagating large quantities of M. leprae, and they are now advancing as models of leprosy pathogenesis and nerve damage. Although armadillos are exotic laboratory animals, the recently completed whole genome sequence for this animal is enabling researchers to undertake more sophisticated molecular studies and to develop armadillo-specific reagents. These advances will facilitate the use of armadillos in piloting new therapies and diagnostic regimens, and will provide new insights into the oldest known infectious neurodegenerative disorder.

Usage of signaling in neurodegeneration and regeneration of peripheral nerves by leprosy bacteria.

Multiple signaling pathways play key regulatory roles during the development of peripheral nervous system (PNS) and also in neuroregeneration process following nerve degeneration. Schwann cells, the glial cells of the PNS, by interacting with neuronal (axonal) ligands, mainly neuregulins via receptor tyrosine kinase (RTK) complex, ErbB2/ErbB3, initiate intracellular signaling pathways to drive proliferation and differentiation of Schwann cells, both during development and the process of regeneration and re-myelination after nerve injury. One of the major signaling kinases, extracellular signal-regulated kinase-1/2 (ERK1/2), that is also a downstream signaling pathway of neuregulin-ErbB2/ErbB3 activation, has been identified as a key regulator of Schwann cell proliferation, differentiation, demyelination and nerve regeneration. Recent studies have provided evidence that the bacterium that causes human leprosy, Mycobacterium leprae that has a unique capacity to invade Schwann cells of the adult PNS, utilizes the neuregulin-ErbB2/ErbB3 associated signaling network to the bacterial advantage. M. leprae directly bind to ErbB2 on myelinated Schwann cells and activate the RTK by a novel route that bypasses the classical neuregulin/growth factor-induced ErbB2-ErbB3 heterodimerization, and subsequently induce downstream the canonical Erk1/2 signaling, leading to myelin breakdown and subsequent axonal damage. This initial injury provides a survival advantage for M. leprae as it induces de-differentiation and generates myelin-free cells, which are highly susceptible to M. leprae invasion and promote bacterial survival. Once invaded M. leprae activate Erk1/2 via a non-canonical pathway and subsequently increase the cell proliferation and maintain the infected cells in de-differentiated state, thereby preventing remyelination. Therefore, by subverting major RTKs and signaling pathways in adult Schwann cells M. leprae appear to propagate the bacterial niche and maintain survival within the PNS. These studies may also provide new insights into our understanding of signaling mechanisms involve in both neurodegeneration and neuroregeneration.

Introduction to the review series Autophagy in Higher Eukaryotes--a matter of survival or death.

Single celled eukaryotes utilize autophagy (or self-consumption) to adapt to fluctuating energy sources in the environment. The identification in multicellular organisms of orthologs of autophagy-related yeast genes has led to some of the major advances in the molecular dissection of the pathway in the last decade. In higher eukaryotes, autophagy is much more than a 'stress response' pathway. The complexity of multicellular systems calls for greater sophistication and coordination not only in regulating the stress response but also in sustaining normal physiological functions and a homeostatic environment in the whole organism. The review series on 'Autophagy in Higher Eukaryotes--a matter of survival or death' in the current issue comprises a variety of perspectives on the role of autophagy in cell growth, survival and death, in neurodegeneration, tumor suppression and tumor progression. For example, Høyer-Hansen and Jäättellä cogitate on the emergence of autophagy as a target in cancer therapy. In addition, Sanjuan and Green examine its role in the defense against microbial pathogens and Sachdeva and Thompson offer an intriguing look at autophagy in the context of circadian clocks and diurnal rhythms. Presented below are some of the salient points from these perspectives.

Facial onset sensory and motor neuronopathy (FOSMN syndrome): a novel syndrome in neurology.

A 'syringomyelia-like' syndrome has been infrequently reported in neurological disorders such as Tangiers disease and lepromatous leprosy. This study reports a novel 'syringomyelia-like' syndrome in four adult male patients, which we have termed facial onset sensory and motor neuronopathy, or FOSMN syndrome, that appears to have a neurodegenerative aetiology. Clinical, neurophysiological and pathological data of four patients were reviewed, including the autopsy in one patient. Four male patients (mean age at onset 43), initially developed paraesthesiae and numbness in a trigeminal nerve distribution, which slowly progressed to involve the scalp, neck, upper trunk and upper limbs in sequential order. Motor manifestations, including cramps, fasciculations, dysphagia, dysarthria, muscle weakness and atrophy developed later in the course of the illness. Neurophysiological findings revealed a generalized sensory motor neuronopathy of caudally decreasing severity in all four patients. Autopsy in one patient disclosed loss of motoneurons in the hypoglossal nucleus and cervical anterior horns, along with loss of sensory neurons in the main trigeminal sensory nucleus and dorsal root ganglia. FOSMN syndrome appears to be a slowly progressive neurodegenerative disorder, whose pathogenesis remains to be determined.

Thalidomide-based TNF-alpha inhibitors for neurodegenerative diseases.

Inflammatory processes associated with the over-production of cytokines, particularly of TNF-alpha, accompany numerous neurodegenerative diseases, such as Alzheimer's disease, in addition to numerous systemic conditions, exemplified by rheumatoid arthritis and erythema nodosum leprosum (ENL). TNF-alpha has been validated as a drug target with Remicade and Enbrel available as prescription medications. Both, however, are large macromolecules, require injection and have limited brain access. The classical drug, thalidomide is being increasingly used in the clinical management of a wide spectrum of diseases. As its clinical value in treating ENL derives from its TNF-alpha inhibitory activity, thalidomide was chosen for structural modification for the discovery of novel and more potent isosteric analogues with appropriate lipophilicity to insure high brain penetration. TNF-alpha inhibitory activity was evaluated against lipopolysacharide (LPS) stimulated peripheral blood mononuclear cells (PBMC) in cell culture, whose viability was quantified to differentiate reductions in TNF-alpha secretion from that associated with cellular toxicity. Specific analogues potently inhibited TNF-alpha secretion, compared to thalidomide. This involved a post-transcriptional mechanism, as they decreased TNF-alpha mRNA stability via its 3'-untranslated region (UTR), as determined by luciferase activity in stably transfected cells with and without the 3'-UTR of human TNF-alpha.

Rifampicin inhibits neurodegeneration in the optic nerve transection model in vivo and after 1-methyl-4-phenylpyridinium intoxication in vitro.

Rifampicin is an antibacterial drug which is highly effective in the treatment of tuberculosis and leprosy. It has been shown to exert antioxidative as well as anti-apoptotic effects. In this study, the neuroprotective effect of rifampicin was examined after 1-methyl-4-phenylpyridinium (MPP+)-induced dopaminergic cell death in vitro, and on the survival of retinal ganglion cells after optic nerve transection in vivo. Rifampicin administration significantly increased the number of surviving dopaminergic neurons after MPP+ intoxication as compared to control cultures. No cytotoxic effects were noted even at final rifampicin concentrations of 100 microM. In the rifampicin-treated group, retinal ganglion cell survival was significantly increased after axotomy as compared with vehicle-treated and phosphate-buffered saline-treated control animals. These results suggest that rifampicin is able to prevent neuronal degeneration in cell death paradigms involving oxidative stress and activation of apoptotic pathways. It may thus play a role in the future treatments of neurodegenerative disorders.

Comparative proteomics of the Mycobacterium leprae binding protein myelin P0: its implication in leprosy and other neurodegenerative diseases.

Mycobacterium leprae, the causative agent of leprosy invades Schwann cells of the peripheral nerves leading to nerve damage and disfigurement, which is the hallmark of the disease. Wet experiments have shown that M. leprae binds to a major peripheral nerve protein, the myelin P zero (P0). This protein is specific to peripheral nerve and may be important in the initial step of M. leprae binding and invasion of Schwann cells which is the feature of leprosy. Though the receptors on Schawann cells, cytokines, chemokines and antibodies to M. leprae have been identified the molecular mechanism of nerve damage and neurodegeneration is not clearly defined. Recently pathogen and host protein/nucleotide sequence similarities (molecular mimicry) have been implicated in neurodegenerative diseases. The approach of the present study is to utilise bioinformatic tools to understand leprosy nerve damage by carrying out sequence and structural similarity searches of myelin P0 with leproma and other genomic database. Since myelin P0 is unique to peripheral nerve, its sequence and structural similarities in other neuropathogens have also been noted. Comparison of myelin P0 with the M. leprae proteins revealed two characterised proteins, Ferrodoxin NADP reductase and a conserved membrane protein, which showed similarity to the query sequence. Comparison with the entire genomic database (www.ncbi.nlm.nih.gov) by basic local alignment search tool for proteins (BLASTP) and fold classification of structure-structure alignment of proteins (FSSP) searches revealed that myelin P0 had sequence/structural similarities to the poliovirus receptor, coxsackie-adenovirus receptor, anthrax protective antigen, diphtheria toxin, herpes simplex virus, HIV gag-1 peptide, and gp120 among others. These proteins are known to be associated directly or indirectly with neruodegeneration. Sequence and structural similarities to the immunoglobin regions of myelin P0 could have implications in host-pathogen interactions, as it has homophilic adhesive properties. Although these observed similarities are not highly significant in their percentage identity, they could be functionally important in molecular mimicry, receptor binding and cell signaling events involved in neurodegeneration.

Comparative proteomics of the Mycobacterium leprae binding protein myelin P0: its implication in leprosy and other neurodegenerative diseases

Mycobacterium leprae, the causative agent of leprosy invades Schwann cells of the peripheral nerves leading to nerve damage and disfigurement, which is the hallmark of the disease. Wet experiments have shown that M. leprae binds to a major peripheral nerve protein, the myelin P zero (P0). This protein is specific to peripheral nerve and may be important in the initial step of M. leprae binding and invasion of Schwann cells which is the feature of leprosy. Though the receptors on Schawann cells, cytokines, chemokines and antibodies to M. leprae have been identified the molecular mechanism of nerve damage and neurodegeneration is not clearly defined. Recently pathogen and host protein/nucleotide sequence similarities (molecular mimicry) have been implicated in neurodegenerative diseases. The approach of the present study is to utilise bioinformatic tools to understand leprosy nerve damage by carrying out sequence and structural similarity searches of myelin P0 with leproma and other genomic database. Since myelin P0 is unique to peripheral nerve, its sequence and structural similarities in other neuropathogens have also been noted. Comparison of myelin P0 with the M. leprae proteins revealed two characterised proteins, Ferrodoxin NADP reductase and a conserved membrane protein, which showed similarity to the query sequence. Comparison with the entire genomic database (www.ncbi.nlm.nih.gov) by basic local alignment search tool for proteins (BLASTP) and fold classification of structure-structure alignment of proteins (FSSP) searches revealed that myelin P0 had sequence/structural similarities to the poliovirus receptor, coxsackie-adenovirus receptor, anthrax protective antigen, diphtheria toxin, herpes simplex virus, HIV gag-1 peptide, and gp120 among others. These proteins are known to be associated directly or indirectly with neruodegeneration. Sequence and structural similarities to the immunoglobin regions of myelin P0 could have implications in host-pathogen interactions, as it has homophilic adhesive properties. Although these observed similarities are not highly significant in their percentage identity, they could be functionally important in molecular mimicry, receptor binding and cell signaling events involved in neurodegeneration.