ABSTRACT
BACKGROUND: The cause of neurodegeneration in progressive forms of multiple sclerosis is unknown. We investigated the impact of specific neuroinflammatory markers on human neurons to identify potential therapeutic targets for neuroprotection against chronic inflammation. METHODS: Surface immunocytochemistry directly visualized protease-activated receptor-1 (PAR1) and interleukin-1 (IL-1) receptors on neurons in human postmortem cortex in patients with and without neuroinflammatory lesions. Viability of cultured neurons was determined after exposure to cerebrospinal fluid from patients with progressive multiple sclerosis or purified granzyme B and IL-1ß. Inhibitors of PAR1 activation and of PAR1-associated second messenger signaling were used to elucidate a mechanism of neurotoxicity. RESULTS: Immunohistochemistry of human post-mortem brain tissue demonstrated cells expressing higher amounts of PAR1 near and within subcortical lesions in patients with multiple sclerosis compared to control tissue. Human cerebrospinal fluid samples containing granzyme B and IL-1ß were toxic to human neuronal cultures. Granzyme B was neurotoxic through activation of PAR1 and subsequently the phospholipase Cß-IP3 second messenger system. Inhibition of PAR1 or IP3 prevented granzyme B toxicity. IL-1ß enhanced granzyme B-mediated neurotoxicity by increasing PAR1 expression. CONCLUSIONS: Neurons within the inflamed central nervous system are imperiled because they express more PAR1 and are exposed to a neurotoxic combination of both granzyme B and IL-1ß. The effects of these inflammatory mediators may be a contributing factor in the progressive brain atrophy associated with neuroinflammatory diseases. Knowledge of how exposure to IL-1ß and granzyme B act synergistically to cause neuronal death yields potential novel neuroprotective treatments for neuroinflammatory diseases.
Subject(s)
Cell Survival/drug effects , Granzymes/toxicity , Interleukin-1beta/toxicity , Receptor, PAR-1/agonists , Receptor, PAR-1/metabolism , Aged , Aged, 80 and over , Cell Survival/physiology , Cells, Cultured , Dose-Response Relationship, Drug , Drug Synergism , Female , Humans , Induced Pluripotent Stem Cells/drug effects , Induced Pluripotent Stem Cells/pathology , Male , Middle Aged , Multiple Sclerosis/cerebrospinal fluid , Multiple Sclerosis/pathologyABSTRACT
Peptidylprolyl isomerase cyclophilins play critical roles in a variety of biological processes. Recent findings that cyclophilins are present at high levels in the CNS and that cyclosporin A may possess neuroprotective/neurotrophic effects have prompted us to search for nonimmunosuppressant small molecule cyclophilin ligands. To this end, we report the lead identification through "virtual screening" and the synthesis of our first series of non-peptidic cyclophilin ligands, along with the preliminary biological results.
Subject(s)
Cyclophilin A/antagonists & inhibitors , Neuroprotective Agents/chemical synthesis , Urea/analogs & derivatives , Urea/chemical synthesis , Animals , Cell Death/drug effects , Cells, Cultured , Combinatorial Chemistry Techniques , Databases, Factual , Ganglia, Spinal/drug effects , Ganglia, Spinal/ultrastructure , Ligands , Mice , Models, Molecular , Motor Neurons/cytology , Motor Neurons/drug effects , Neurites/drug effects , Neuroprotective Agents/pharmacology , Structure-Activity Relationship , Urea/pharmacologyABSTRACT
The recent discovery that small molecule ligands for the peptidyl-prolyl isomerase (PPIase) FKBP12 possess powerful neuroprotective and neuroregenerative properties in vitro and in vivo suggests therapeutic utility for such compounds in neurodegenerative disease. The neurotrophic effects of these compounds are independent of the immunosuppressive pathways by which drugs such as FK506 and rapamycin operate. Previous work by ourselves and other groups exploring the structure-activity relationships (SAR) of small molecules that mimic only the FKBP binding domain portion of FK506 has focused on esters of proline and pipecolic acid. We have explored amide and thioester analogues of these earlier structures and found that they too are extremely potent in promoting recovery of lesioned dopaminergic pathways in a mouse model of Parkinson's disease. Several compounds were shown to be highly effective upon oral administration after lesioning of the dopaminergic pathway, providing further evidence of the potential clinical utility of a variety of structural classes of FKBP12 ligands.
Subject(s)
Amides/chemical synthesis , Nerve Regeneration/drug effects , Pipecolic Acids/chemical synthesis , Proline/analogs & derivatives , Proline/chemical synthesis , Sulfhydryl Compounds/chemical synthesis , Tacrolimus Binding Protein 1A/antagonists & inhibitors , 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine , Administration, Oral , Amides/chemistry , Amides/pharmacology , Animals , Corpus Striatum/enzymology , Corpus Striatum/pathology , Corpus Striatum/ultrastructure , Dopamine Agents , Immunohistochemistry , Ligands , Mice , Molecular Mimicry , Neurites/drug effects , Neuroprotective Agents/chemical synthesis , Neuroprotective Agents/chemistry , Neuroprotective Agents/pharmacology , Parkinson Disease, Secondary/chemically induced , Parkinson Disease, Secondary/drug therapy , Parkinson Disease, Secondary/pathology , Pipecolic Acids/chemistry , Pipecolic Acids/pharmacology , Proline/chemistry , Proline/pharmacology , Structure-Activity Relationship , Substantia Nigra/enzymology , Substantia Nigra/pathology , Substantia Nigra/ultrastructure , Sulfhydryl Compounds/chemistry , Sulfhydryl Compounds/pharmacology , Tacrolimus Binding Protein 1A/chemistry , Tyrosine 3-Monooxygenase/metabolismABSTRACT
Using simple, inexpensive equipment, we have used solution-phase parallel synthesis to rapidly prepare hundreds of sulfonamide- and urea-containing FKBP inhibitors, resulting in rapid identification of extremely potent compounds in these series.
