The therapeutic effect of glatiramer acetate in a murine model of inflammatory bowel disease is mediated by anti-inflammatory T-cells.

Inflammatory bowel diseases (IBDs) are complex multifactorial immunological disorders characterized by dysregulated immune reactivity in the gut and imbalance between pro-inflammatory and anti-inflammatory reactivity. The therapeutic effect of the immunomodulatory drug glatiramer acetate (GA, Copaxone, copolymer 1) has been established in several IBD models, including trinitrobenzene sulfonic acid (TNBS) and dextran sulfate sodium (DSS)-induced colitis, as well as in a spontaneous colitis model. In the present study we investigated the mechanism of action of GA and cells specifically induced by it. Immunization of naive mice by GA, generated a lymphocyte population of the Th2/3 subtype, that drastically reduced disease manifestations upon their adoptive transfer to mice with DSS colitis. This was demonstrated by the substantial decrease in weight loss, intestinal bleeding and diarrhea, as well as by the prevention of macroscopic and microscopic colonic damage. In contrast, adoptive transfer of control lysozyme-specific cells did not induce any beneficial effect on the disease. Moreover, GA-specific short-term T-cell lines, either exogenously labeled or genetically marked, adoptively transferred by the intraperitoneal route to colitis-induced mice, localized in the inner layers of the colon and secreted in situ the regulatory cytokine TGF-beta. These results demonstrate the accumulation of GA-specific Th2/3 cells secreting regulatory cytokines in the injured colon, and thus draw a direct linkage between the therapeutic effect of GA in IBD and an immunomodulatory effect at the site in which the pathological process occurs.

Monitoring drug-induced neurodegeneration by imaging of peripheral benzodiazepine receptors.

Several drugs of abuse are known to produce an array of deleterious effects, including alterations in neuronal circuitry and, ultimately, neuronal degeneration. For instance, methamphetamine was shown to induce substantial nigrostriatal dopaminergic terminal damage, including an increase in glial fibrillary acidic protein, a marker for astrocyte proliferation. Nevertheless, there was almost no attempt to define neurodegeneration by measuring the abundance of reactive microglia. In fact, some investigators fail to differentiate between astrocytes and microglia and claim glial fibrillary acidic protein to be a marker for gliosis. To date, there are numerous methods designed to assess brain neuropathologies resulting from a wide arsenal of insults. Regardless of the cause of neuronal damage, reactive glial cells always appear at and around the site of degeneration. These cells are distinguished by the exceptional abundance of peripheral benzodiazepine receptors (PBRs; omicron3 sites), particularly as compared to surrounding neurons. Measuring the binding of specific ligands to these PBRs (for example, [3H]PK 11195) offers a unique indirect marker for reliable impairment estimation in the central nervous system. Moreover, the availability of agents such as [11C]PK 11195 paved the road to in vivo animal and human brain positron emission tomography scanning, demonstrating inflammation-like processes in several diseases. Additionally, the measurement of increased binding of PBR ligands provides a faithful indicator for the behavioral and cognitive deficits accompanying neuronal injury.

M1 muscarinic agonists can modulate some of the hallmarks in Alzheimer's disease: implications in future therapy.

M1 muscarinic receptors (M1 mAChRs) play a role in an apparent linkage of three major hallmarks of Alzheimer's disease (AD): beta-amyloid (Abeta) peptide; tau hyperphosphorylation and paired helical filaments (PHFs); and loss of cholinergic function conducive to cognitive impairments. We evaluated the M1 muscarinic agonists AF102B (Cevimeline, EVOXAC trade mark : prescribed for Sjøgren's syndrome), AF150(S), and AF267B on some of these hallmarks of AD. Activation of M1 mAChRs with these agonists leads, inter alia, to enhanced secretion of amyloid precursor protein (alpha-APP), (via alpha-secretase activation), to decreased Abeta (via gamma-secretase inhibition), and to inhibition of Abeta- and/or oxidative stress-induced cell death. In several animal models mimicking different aspects of AD, these drugs restored cognitive impairments, and in select cases induced a decrease in brain Abeta elevation, with a high safety margin, following po administration. Notably, in mice with small hippocampi, unlike rivastigmine and nicotine, AF150(S) and AF267B restored cognitive impairments also on escape latency in a Morris water maze paradigm, in reversal learning. Studies from other labs showed that AF102B and talsaclidine (another M1 agonist) decreased cerbrospinal fluid (CSF) Abeta in AD patients following chronic treatment, being the first reported drugs with such a profile. The clinical significance of these studies remains to be elucidated, yet based on in vivo (rabbits) and in vitro studies (cell cultures), our M1 agonists can decrease brain Abeta, owing to a novel and dual complementary effect (e.g., inhibition of gamma-secretase and activation of alpha-secretase). Remarkably, although M1 agonists can decrease CSF Abeta in AD patients, an increased AD-type pathology in Parkinson's disease was recently been associated with chronic antimuscarinic treatment. In another aspect, these agonists decreased tau hyperphosphorylation in vitro and in vivo. Notably, nicotinic agonists or cholinesterase inhibitors increased tau hyperphosphorylation. In summary, the M1 agonists tested are effective on cognition and behavior and show unique disease-modifying properties owing to beneficial effects on major hallmarks of AD. This may place such drugs in the first line of modern AD therapies (e.g., beta- or gamma-secretase inhibitors, vaccines against Abeta, statins, and inhibitors of tau hyperphosphorylation).

Anticholinergic and antiglutamatergic agents protect against soman-induced brain damage and cognitive dysfunction.

Soman, a powerful inhibitor of acetylcholinesterase, causes an array of toxic effects in the central nervous system including convulsions, learning and memory impairments, and, ultimately, death. We report on the protection afforded by postexposure antidotal treatments, combined with pyridostigmine (0.1 mg/kg) pretreatment, against these consequences associated with soman poisoning. Scopolamine (0.1 mg/kg) or caramiphen (10 mg/kg) were administered 5 min after soman (1.2 LD50), whereas TAB (i.e., TMB4, atropine, and benactyzine, 7.5, 3, and 1 mg/kg, respectively) was injected in rats concomitant with the development of toxic signs. Atropine (4 mg/kg) was given to the two former groups at the onset of toxic symptoms. Caramiphen and TAB completely abolished electrographic seizure activity while scopolamine treatment exhibited only partial protection. Additionally, no significant alteration in the density of peripheral benzodiazepine receptors was noted following caramiphen or TAB administration, while scopolamine application resulted in a complex outcome: a portion of the animals demonstrated no change in the number of these sites whereas the others exhibited markedly higher densities. Cognitive functions (i.e., learning and memory processes) evaluated using the Morris water maze improved considerably by the three treatments when compared to soman-injected animals; the following rank order was observed: caramiphen > TAB > scopolamine. Additionally, statistically significant correlations (r = 0.72, r = 0.73) were demonstrated between two learning parameters and [3H]Ro5-4864 binding to brain membrane. These results show that drugs with a pharmacological profile consisting of anticholinergic and antiglutamatergic properties such as caramiphen and TAB, have a substantial potential as postexposure therapies against intoxication by organophosphates.

AF150(S) and AF267B: M1 muscarinic agonists as innovative therapies for Alzheimer's disease.

The M1 muscarinic agonists AF102B (Cevimeline, EVOXACTM: prescribed in USA and Japan for Sjogren's Syndrome), AF150(S) and AF267B--1) are neurotrophic and synergistic with neurotrophins such as nerve growth factor and epidermal growth factor; 2) elevate the non-amyloidogenic amyloid precursor protein (alpha-APPs) in vitro and decrease beta-amyloid (A beta) levels in vitro and in vivo; and 3) inhibit A beta- and oxidative-stress-induced cell death and apoptosis in PC12 cells transfected with the M1 muscarinic receptor. These effects can be combined with the beneficial effects of these compounds on some other major hallmarks of Alzheimer's disease (AD) (e.g. tau hyperphosphorylation and paired helical filaments [PHF]; and loss of cholinergic function conducive to cognitive impairments.) These drugs restored cognitive impairments in several animal models for AD, mimicking different aspects of AD, with a high safety margin (e.g. AF150[S] >1500 and AF267B >4500). Notably, these compounds show a high bioavailability and a remarkable preference for the brain vs. plasma following p.o. administration. In mice with small hippocampi, unlike rivastigmine and nicotine, AF150(S) and AF267B restored cognitive impairments also on escape latency in a Morris water maze paradigm in reversal learning. Furthermore, in aged and cognitively impaired microcebes (a natural animal model that mimics AD pathology and cognitive impairments), prolonged treatment with AF150(S) restored cognitive and behavioral impairments and decreased tau hyperphosphorylation, PHF and astrogliosis. Our M1 agonists, alone or in polypharmacy, may present a unique therapy in AD due to their beneficial effects on major hallmarks of AD.

Caramiphen and scopolamine prevent soman-induced brain damage and cognitive dysfunction.

Exposure to soman, a toxic organophosphate nerve agent, causes severe adverse effects and long term changes in the peripheral and central nervous systems. The goal of this study was to evaluate the ability of prophylactic treatments to block the deleterious effects associated with soman poisoning. scopolamine, a classical anticholinergic agent, or caramiphen, an anticonvulsant anticholinergic drug with anti-glutamatergic properties, in conjunction with pyridostigmine, a reversible cholinesterase inhibitor, were administered prior to sbman (1 LD50). Both caramiphen and scopolamine dramatically attenuated the process of cell death as assessed by the binding of [3H]RoS-4864 to peripheral benzodiazepine receptors (omega3 sites) on microglia and astrocytes. In addition, caramiphen but not scopolamine, blocked the soman-evoked down-regulation of [3H]AMPA binding to forebrain membrane preparations. Moreover, cognitive tests utilizing the Morris water maze, examining learning and memory processes as well as reversal learning, demonstrated that caramiphen abolished the effects of soman intoxication on learning as early as the first trial day, while scopolamine exerted its effect commencing at the second day of training. Whereas the former drug completely prevented memory deficits, the latter exhibited partial protection. Both agents equally blocked the impairment of reversal learning. In addition, there is a significant correlation between behavioral parameters and [3H]RoS-4864 binding to forebrain membrane preparations of rats, which participated in these tests (r(21) = 0.66, P < 0.001; r(21) = 0.66, P < 0.001, -0.62, P < 0.002). These results demonstrate the beneficial use of drugs exhibiting both anti-cholinergic and anti-glutamatergic properties for the protection against changes in cognitive parameters caused by nerve agent poisoning. Moreover, agents such as caramiphen may eliminate the need for multiple drug therapy in organophosphate intoxications.