Use of poly-Glu,Tyr for neuroprotective therapy

Details Use of poly-Glu,Tyr for neuroprotective therapy Use of poly-Glu,Tyr for neuroprotective therapy

2001-06-28

2004-12-28

Kemmerer, Elizabeth (Department: 1647)

Drug, bio-affecting and body treating compositions

Designated organic active ingredient containing

Peptide containing doai

C514S012200

Reexamination Certificate

active

06835711

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to compositions and methods for the promotion of nerve regeneration or prevention or inhibition of neuronal degeneration to ameliorate the effects of injury or disease of the nervous system (NS). In particular, the invention relates to compositions comprising poly-Glu,Tyr and/or activated T cells treated wite poly-Glu,Tyr, to protect central nervous system (CNS) cells from glutamate toxicity, to promote nerve regeneration or to prevent or inhibit neuronal degeneration caused by injury or disease of nerves within the CNS or peripheral nervous system (PNS) of a human subject. The compositions of the present invention may be administered alone or may be optionally administered in any desired combination.
ABBREVIATIONS
CFA: complete Freund's adjuvant; CNS: central nervous system; MBP: myelin basic protein; NS: nervous system; PBS: phosphate-buffered saline; pEY: Poly-Glu,Tyr; PNS: peripheral nervous system;; Poly-Glu,Tyr: copolymer poly-Glu
50
Tyr
50
, a random heterocopolymer of L-glutamic acid and L-tyrosine,; RGC: retinal ganglion cells.
BACKGROUND OF THE INVENTION
The nervous system comprises the central (CNS) and the peripheral nervous system (PNS). The CNS is composed of the brain spinal cord and visual system; the PNS consists of all of the other neural elements, namely the nerves and ganglia outside of the brain and spinal cord.
Damage to the nervous system may result from a traumatic injury, such as penetrating trauma or blunt trauma, or a disease or disorder, including but not limited to Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis (ALS), diabetic neuropathy, senile dementia, stroke and ischemia.
Maintenance of CNS integrity is a complex “balancing act” in which compromises are struck with the immune system. In most tissues, the immune system plays an essential part in protection, repair, and healing. In the CNS, because of its unique immune privilege, immunological reactions are relatively limited. A growing body of evidence indicates that the failure of the mammalian CNS to achieve functional recovery after injury is a reflection of an ineffective dialog between the damaged tissue and the immune system. For example, the restricted communication between the CNS and blood-borne macrophages affects the capacity of axotomized axons to regrow; transplants of activated macrophages can promote CNS regrowth.
Activated T cells have been shown to enter the CNS parenchyma, irrespective of their antigen specificity, but only T cells capable of reacting with a CNS antigen seem to persist there (Hickey et al, 1991). T cells reactive to antigens of CNS white matter, such as myelin basic protein (MBP), can induce the paralytic disease experimental autoimmune encephalomyelitis (EAE) within several days of their inoculation into naive recipient rats (Ben-Nun, 1981a). Anti-MBP T cells may also be involved in the human disease multiple sclerosis (Ota, K. et al, 1990). However, despite their pathogenic potential, anti-MBP T cell clones are present in the immune systems of healthy subjects (Pette et al, 1990). Activated T cells, which normally patrol the intact CNS, transiently accumulate at sites of central nervous system white matter lesions (Hirschberg et al, 1998).
A catastrophic consequence of CNS injury is that the primary damage is often compounded by the gradual secondary loss of adjacent neurons that apparently were undamaged, or only marginally damaged, by the initial injury (McIntosh, 1993). The primary lesion causes changes in extracellular ion concentrations, elevation of amounts of free radicals, release of neurotransmitters, depletion of growth factors, and local inflammation. These changes trigger a cascade of destructive events in the adjacent neurons that initially escaped the primary injury (Lynch et al, 1994). This secondary damage is mediated by activation of voltage-dependent or agonist-gated channels, ion leaks, activation of calcium-dependent enzymes such as proteases, lipases and nucleases, mitochondrial dysfunction and energy depletion, culminating in neuronal cell death. The widespread loss of neurons beyond the loss caused directly by the primary injury has been called “secondary degeneration.”
One of the most common mediators which cause self-propagation of the diseases even when the primary risk factor is removed or attenuated is glutamate, an excitatory amino acid capable of displaying dual activity: playing a pivotal role in normal CNS functioning as an essential neuro-transmitter, but becoming toxic when its physiological levels are exceeded. Elevation of glutamate has been reported in many CNS disorders. In its role as an excitotoxic compound, glutamate is one of the most common mediators of toxicity in acute and chronic (including optic nerve degeneration in glaucoma) degenerative disorders (Pitt et al., 2000). Endogenous glutamate has been attributed to the brain damage occurring acutely after status epilepticus, cerebral ischemia or traumatic brain injury. It may also contribute to chronic neurodegeneration in such disorders as amyotrophic lateral sclerosis and Huntington's chorea.
Intensive research has been devoted to attenuating the cytotoxic effect of glutamate by the use of locally acting drugs, such as N-methyl-D-aspartate (NMDA)-receptor antagonists. Conventional therapy of this type is often unsatisfactory, however, as in neutralizing the toxic effect it is likely to interfere with the physiological functioning. In humans, such compounds have psychotropic and other side effects that make them unsuitable as therapeutic agents. They also have the disadvantage of interfering with the essential physiological functioning of glutamate as a ubiquitous CNS neurotransmitter. Because glutamate activity is essential for normal physiological functioning, yet is potentially devastating after acute injury or in chronic CNS disorders, any attempt to neutralize its harmful effect must do so without eliminating its essential activity at other sites in the body.
Another tragic consequence of CNS injury is that neurons in the mammalian CNS do not undergo spontaneous regeneration following an injury. Thus, a CNS injury causes permanent impairment of motor and sensory functions.
Spinal cord lesions, regardless of the severity of the injury, initially result in a complete functional paralysis known as spinal shock. Some spontaneous recovery from spinal shock may be observed, starting a few days after the injury and tapering off within three to four weeks. The less severe the insult, the better the functional outcome. The extent of recovery is a function of the amount of initially undamaged tissue minus the loss due to secondary degeneration. Recovery from injury would be improved by neuroprotective treatment that could reduce secondary degeneration. For example, alleviation of the effect of glutamate is a frequent target of neuroprotective drug development. Among the drugs which are being developed for this purpose are N-methyl-D-aspartate (NMDA)-receptor or alpha-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid (AMPA)-receptor antagonists. These drugs will inevitably have severe side effects as they interfere with the functioning of NMDA and AMPA receptors, which are crucial for normal CNS activity. One of the most intensely studied NMDA-receptor antagonists is MK801, which provides effective neuroprotection but with severe side effects. In animal models of cerebral ischemia and traumatic brain injury, NMDA and AMPA receptor antagonists protect against acute brain damage and delayed behavioral deficits. Such compounds are undergoing testing in humans, but therapeutic efficacy has yet to be established. Other clinical conditions that may respond to drugs acting on glutamatergic transmission include epilepsy, amnesia, anxiety, hyperalgesia and psychosis (Meldrum, 2000).
In the laboratory of the present inventors, it has recently been discovered that activated T cells that recognize an antigen of the NS of the patient confer neuroprotection.

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