The invention relates to methods and compositions for immune modulation.
The immune system is a complex, multifactorial defense system that protects the body from a wide range of infectious diseases including viruses, bacteria, parasites and fungi. Although critical for our survival, in certain instances, such as autoimmune disease, transplant rejection, allergies and inflammation, the immune system can be the cause of illness. In such instances it is desirable to suppress or tolerize the immune response.
The immune system is comprised of a large variety of cells derived from undifferentiated hematopoietic stem cells and includes phagocytes (such as neutrophil polymorphs, monocytes, macrophages and dendritic cells) and lymphocytes such as T cells and B cells and natural killer cells.
Dendritic cells are interesting immune cells as, depending on the circumstances, they can either activate or suppress an immune response. With regard to immune activation, dendritic cells (DCs) are potent lymphocyte stimulators and are extremely effective antigen presenting cells. Recently, considerable interest has been generated in the potential use of dendritic cells for the therapy of cancer and infectious diseases. DCs pulsed with tumour peptides elicit protective and antitumour immunity in mice (Mayordama et al., 1995). Patients with B cell lymphomas have been successfully vaccinated with autologous antigen-pulsed DC directly isolated from the blood (Hsu et al., 1996). Flt3 ligand, which induces DC maturation, resulted in tumour regression and antitumour immune response in mice (Lynch et al., 1997). Unfortunately, advances in treatment of tumors with DCs have been limited by their trace level in vivo. Efforts in this area are directed at increasing DC numbers and level of activation. With regard to tolerance, dendritic cells have recently been shown to be involved in the induction of central as well as peripheral tolerance and may be useful in treating autoimmunity, allergies and transplantation rejection.
The present inventors have prepared a peptide derived from apolipoprotein E termed apoEp1.B which includes amino acids 239-252 of the apolipoprotein E. The inventors have found that surprisingly, apoEp1.B is a potent immune modulator that acts on a variety of immune cells. Interestingly, apoEp1.B is a dual modulator, capable of both inducing and suppressing an immune response. In particular, apoEp1.B has been shown to induce differentiation of immature cells into dendritic cells, to induce tumor cell differentiation and activation, to inhibit inflammation and to inhibit autoimmune disease.
Accordingly, the present invention provides an isolated apoEp1.B peptide comprising amino acids 239-252 of an apolipoprotein E protein. In a preferred embodiment, the present invention provides an isolated apoEp1.B peptide having the amino acid sequence TQQIRLQAEIFQAR (SEQ.ID.NO.: 1) (murine) or AQQIRLQAEAFQAR (SEQ.ID.NO.: 2) (human). The invention also includes analogs, fragments, elongations and derivatives of a peptide of the invention. Analogs and derivatives of the peptides include peptides having the following sequences: TAQIRLQAEIFQAR (SEQ.ID.NO.: 3); TQAIRLQAEIFQAR (SEQ.ID.NO.: 4); TQQARLQAEIFQAR (SEQ.ID.NO.: 5) and TQQIALQAEIFQAR (SEQ.ID.NO.: 6). Fragments and elongations of the peptides include peptides that have the following sequences: QTQQIRLQAEIFQAR (SEQ.ID.NO.: 7) and QQIRLQAEIFQAR (SEQ.ID.NO.: 8). The present invention also provides a nucleic acid molecule encoding the apoEp1.B peptide, or an analog, fragment or derivative thereof.
The present invention further provides a method of immune modulation comprising administering an effective amount of an apoEp1.B peptide or a nucleic acid encoding an apoEp1.B peptide to a cell or animal in need thereof.
According to one embodiment, the peptide can induce immune tolerance. In particular, the present inventors have demonstrated that the apoEp1.B peptide can activate monocytes to differentiate into tolerogenic dendritic cells. The induction of tolerogenic dendritic cells can have a wide variety of therapeutic applications including inflammation, autoimmune disease and transplantation.
In another embodiment,the apoEp1.B peptide is useful in inhibiting inflammation. In a preferred embodiment, the peptide can inhibit atherosclerotic plaque formation in vivo.
In a further embodiment, the apoEp1.B peptide can be used to prevent or treat an autoimmune reaction or disease. The present inventors have also demonstrated that the apoEp1.B peptide can protect NOD mice from developing diabetes. In a preferred embodiment, the autoimmune disease is diabetes.
In a further aspect, the apoEp1.B peptide can be used to induce an immune response by activating immune cells. In one embodiment, the peptide, in combination with other cytokines such as IL-4, GM-CSF, TNFxcex1 and Flt3 ligand may induce immature dendritic cells to differentiate into mature immunogenic dendritic cells. Mature dendritic cells can be used in a wide variety of applications including tumor immunotherapy.
In another aspect, the apoEp1.B peptide can be used to treat tumors of immune origin by inducing their differentiation. In particular, the present inventors have demonstrated that the apoEp1.B peptide can induce the differentiation and activation of monocytic, monoblastic leukemia and lymphoma tumor cells.
Other features and advantages of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples while indicating preferred embodiments of the invention are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.