Drug – bio-affecting and body treating compositions – Whole live micro-organism – cell – or virus containing – Genetically modified micro-organism – cell – or virus
Reexamination Certificate
1996-05-29
2001-08-14
Hauda, Karen M. (Department: 1632)
Drug, bio-affecting and body treating compositions
Whole live micro-organism, cell, or virus containing
Genetically modified micro-organism, cell, or virus
C424S093200, C424S199100, C514S04400A, C435S325000, C435S252100
Reexamination Certificate
active
06274136
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the field of immunotherapy and to the preparation and use of engineered cells having the ability to restore tolerance to self antigens in patients suffering from autoimmune disease. More particularly, this invention relates to the design and construction of a gene encoding an encephalogenic epitope of proteolipid protein (PLP), to methods of in vitro and in vivo expression of a PLP epitope, to methods of in vivo secretion of a PLP epitope, and to methods of transferring the partial PLP gene to a host to ameliorate the progression of an immune response to self antigens derived from myelin proteins.
BACKGROUND OF THE INVENTION
The immune system can respond in two ways when exposed to an antigen. A positive response leads to differentiation of T and B cells, antibody production and to immunologic memory. A negative response leads to suppression or inactivation of specific lymphocytes and to tolerance. Tolerance can be defined as the failure of an organism to mount an immune response against a specific antigen. Normally, an organism is tolerant of its own antigens.
Autoimmune diseases are thought to result from an uncontrolled immune response directed against self antigens. In patients with multiple sclerosis (MS), for example, there is evidence that this attack is against the white matter of the central nervous system and more particularly to white matter proteins. Ultimately, the myelin sheath surrounding the axons is destroyed. This can result in paralysis, sensory deficits and visual problems. MS is characterized by a T cell and macrophage infiltrate in the brain. Autoreactive myelin-specific T cells have been isolated from MS patients, although T cells of the same specificity have been detected in normal individuals. J. M. LaSalle et al.,
J. Immunol
. 147:774-780 (1991), J. M. LaSalle et al.,
J. Exp. Med
. 176:177-186 (1992), J. Correale et al.,
Neurology
. 45:1370-1378 (1995). Presently, the myelin proteins thought to be the target of an immune response in MS include myelin basic protein (MBP), proteolipid protein (PLP), and myelin-oligodendrocyte glycoprotein (MOG). Individuals who do not mount an autoimmune response to self proteins are thought to have control over these responses and are believed to be “tolerant” of self antigens. The evidence, therefore, that MS is caused by pathogenic T cells is necessarily indirect, but the close resemblance which the characteristics of this disease bear to those of the murine model, experimental autoimmune encephalomyelitis (EAE), suggest that MS is indeed caused by an aberrant immune response mediated by T cells.
The EAE mouse model for MS, the subject of intense and fruitful study for several years, displays many of the same histopathological and clinical characteristics as the relapsing remitting forms of MS. The T Lymphocyte in Experimental Allergic Encephalomyelitis, Ann. Rev. Immunol. 8:579-621 (1990). EAE can be induced in SJL mice by injection of mouse spinal cord homogenate (MSCH), MBP, PLP, by the injection of synthetic peptides whose sequences correspond to the major encephalogenic epitopes of myelin basic protein, MBP 84-104, proteolipid protein, PLP 139-151, or by adoptive transfer of activated CD4
+
T
H1
, but not T
H2
cells specific for encephalogenic epitopes. The major encephalogenic epitopes of myelin-derived sequences in EAE, such as MBP, can also activate human T cells of several different haplotypes including HLA-DR2. R. Martin, et al.,
J. Exp. Med
. 173:19-24 (1992). The experimental disease is characterized by a relapsing-remitting course (R-EAE) of neurological dysfunction, perivascular mononuclear infiltration and demyelination. CNS damage is probably mediated by inflammatory cytokines which can activate additional monocytes and macrophages non-specifically. J. E. Blalock, The Immune System. Our Sixth Sense, The Immunologist, 2:8-15 (1994).
Although the initial attack in EAE can be induced by the administration of either T cells specific for MBP or for PLP, close examination of reactivities of T cells in the primary and subsequent relapses demonstrates the presence of T cells which interact with specificities other than the inducing epitopes. This expansion of encephalogenic epitopes is termed “determinant spreading”. S. D. Miller and W. J. Karpus,
Immunology Today
15:356-361 (1994), P. V. Lehman, T. Forsthuber, A. Miller, and E. E. Sercarz,
Nature
358-155-157 (1992), H. Jiang, S-I. Zhang and B. Pernis,
Science
256:1213-1215 (1992). Antigen specific treatment would therefore, be expected to be more effective when administered early in the course of the disease, before the onset of increasing epitope complexity and eventual non-specific inflammation.
The goal of immunologic therapy is to restore tolerance without suppressing the entire immune system which can lead to complications such as infection, hemorrhage, and cancer. Drugs currently used to treat autoimmune diseases are non-specific immunosuppressive agents, such as anti-inflammatory agents or drugs which can block cell proliferation or depress proinflammatory cytokines. In general, these agents are effective for limited duration and subject to devastating complications.
It is desirable to suppress the immune system in a more specific way to control the response to self-antigens and theoretically “cure” the disease without down-regulating the entire immune system. Several specific immunotherapies have been hypothesized and tested in recent years, many of which are impractical or do not work in humans. For example, high affinity peptides can be synthesized which interact with MHC class II molecules and prevent the binding of encephalogenic peptides, thereby preventing the activation of pathogenic T cells. A. Franco et al.,
The Immunologist
2:97-102 (1994). This approach is disadvantageous in that it is difficult to obtain effective concentrations of inhibitor peptides in vivo. G. Y. Ishioka et al.,
J. Immunol
. 152:4310-4319. In an alternate strategy, peptides which are analogs of encephalogenic sequences have been shown to antagonize the T cell receptors of antigen-specific T cells, rendering them unreactive, although the exact mechanism is at present unknown. S. C. Jameson et al.,
J. Exp. Med
177:1541-1550 (1993), N. Karin et al.,
J. Exp. Med
. 180:2227-2237 (1994), V. K. Kuchroo et al.,
J. Immunol
. 153:3326-3336 (1994). Oral administration of myelin has been tested and found to induce a state of immunological unresponsiveness thought to be mediated by the induction of suppressor T cell or of anergy. H. L. Weiner et al.,
Annu. Rev. Immunol
. 12:809-837 (1994), C. C. Whitacre et al.,
J. Immunol
. 147:2155-2163 (1991), S. J. Khoury et al.,
J. Exp. Med
. 176:1355-1364 (1992). This treatment has been found to be efficacious for some but not all individuals. H. L. Weiner et al.,
Science
259:1321-1324 (1993). Thus, it is evident that improvements are needed to treat MS and other autoimmune disorders with an effective, immunospecific approach.
SUMMARY OF THE INVENTION
The present invention addresses the disadvantages present in the prior art. In general, the invention is based on the discovery that recombinant DNA technology and cell transfer may be employed to restore tolerance to one's own tissues. The present invention provides a means of preparing and constructing a gene, that when expressed and secreted in vivo, can provide a means of halting the progression of an autoimmune disease. In further aspects the invention provides a method to construct a gene encoding a portion of a CNS protein, insert the gene sequence into a vector and transfect a cell line. In further aspects, the invention provides a method to construct a gene encoding a portion of a CNS protein, insert the sequence into a retroviral vector, and transduce a producer fibroblast cell line to generate supernatant containing the recombinant retrovirus. Histocompatible fibroblasts are transduced with the recombinant retrovirus encoding a portion of the CNS protein and are delivered to animals. These fib
McMillan Minnie
Weiner Leslie P.
Beckerleg Anne Marie S.
Hauda Karen M.
McCutchen Doyle Brown & Enersen LLP
University of Southern California
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