Drug – bio-affecting and body treating compositions – Antigen – epitope – or other immunospecific immunoeffector – Amino acid sequence disclosed in whole or in part; or...
Reexamination Certificate
2002-03-28
2003-11-18
Chan, Christina (Department: 1644)
Drug, bio-affecting and body treating compositions
Antigen, epitope, or other immunospecific immunoeffector
Amino acid sequence disclosed in whole or in part; or...
C424S192100, C424S193100, C514S002600, C514S012200, C514S014800, C530S327000, C530S350000
Reexamination Certificate
active
06649166
ABSTRACT:
The present invention relates to peptides and proteins capable of desensitizing, in a specific manner, the great majority of subjects allergic to bee venom, and to compositions containing said peptides or proteins.
Immediate allergy to Hymenoptera (bee, wasp, hornet) affects 15 to 20% of the population, if prick tests are taken into account, but only 0.1 to 0.5% of the population is exposed to an anaphylactic-type accident (1, 2). This allergy is characterized by varying manifestations ranging from local swelling to systemic reactions such as urticaria, angioedema or anaphylactic shock. Given the suddenness of the stings, desensitization (specific immunotherapy or SIT) with venoms constitutes the preferred treatment for this allergy but is not without danger. Indeed, 13% of patients desensitized with bee venom and 5% in the case of wasp venom are victims of side effects (3). The search for a better tolerated and equally effective SIT is therefore necessary, in particular for bee venom.
The speed of the reactions observed in patients allergic to bee venom is characteristic of an immediate-type allergy which is mediated by IgEs specific for the constituents of the venom. The complex mechanism of these reactions is summarized below.
IgEs appear gradually under the repeated action of stings and before any symptom becomes apparent. Although the bee venom comprises numerous peptides and proteins, all the components do not appear to be allergenic (4). Melittin, for example, induces IgEs in only 30% of patients, whereas the proportion increases to more than 90% for phospholipase A2 (PLA2) which is, as a result, considered to be the major allergen (API m1). The protein sequence of bee venom phospholipase A2 (API m1) is illustrated in
FIG. 1
(SEQ ID NO: 8); this sequence is deduced from that of the complementary cDNA (36).
IgEs possess the property of binding, via their Fc fragment, to receptors situated on the tissue mastocytes and the blood basophils. When the allergen forms a complex with the specific IgEs bound to the membrane of the basophils or mastocytes, it causes degranulation of the cells and the release of molecules which are responsible for the principal manifestations observed during an allergic accident. IgEs are not solely responsible for the allergy because although the IgE level is an indicator for the disease, it has no diagnostic value for the state of the patients. It is not rare for patients to have high IgE levels without showing symptoms. The appearance of IgEs in allergic patients results from the production of type TH2 cytokines such as IL-4, IL-5 and IL-13 and is inhibited by the synthesis of IFN-&ggr; (6).
It is mainly the CD4
+
T lymphocytes which produce these cytokines. Specific T cells which secrete more IL-4 than IFN-&ggr; are effectively found in allergic patients, whereas the T cells isolated from nonallergic subjects produce more IFN-&ggr; than IL-4.
The TH2-type CD4
+
T lymphocytes specific for the venom components therefore actively participate in the appearance and the maintenance of the allergy.
To protect the subjects allergic to bee venom, it was proposed long ago to desensitize the allergic subjects by specific immunotherapy (or SIT). The immunological mechanisms of SIT which are responsible for the improvement in the patient's condition remain poorly understood. The induction of specific IgGs and of an IgG4 subclass (7) as well as the generation of suppressive CD8
+
T cells (8) were initially proposed to account for the efficacy of the treatment. However, it was more recently observed that during the desensitization to bee venom, the proliferation of the CD4
+
T lymphocytes specific for the allergen decreases while the secretion of IL-4 and IL-5 decreases (9, 10) or is diverted toward the production of IFN-&ggr; (11). Very similar results were also obtained with pollen allergens (12). These observations appear to indicate that the improvement in the patient's condition results from a peripheral tolerance or from a drift toward a TH1-type profile for the CD4
+
T lymphocytes specific for the allergen. They are furthermore in agreement with experiments carried out in animals. It has indeed been shown for several antigens that under injection conditions similar to those used to desensitize (such as subcutaneous injection) the anergy of the T lymphocytes is induced while a high response is observed for the same antigens when they are injected in the presence of adjuvant (13, 14). All these experiments make it possible to consider the CD4
+
T lymphocytes specific for bee venom as the target cells for immunotherapy.
The CD4
+
T lymphocytes possess a rearranged T receptor which allows them to selectively recognize peptide fragments derived from the degradation of the antigen by the presenting cells and presented by the Major Histocompatibility Complex class II (MHC II) molecules (15). The determinants which these peptide fragments carry and which the T lymphocytes effectively recognize are called T epitopes.
During desensitization, it is these determinants which are recognized by the T lymphocytes and which therefore constitute the basic elements for the production of alternative molecules for specific immunotherapy.
It has indeed been observed in vivo in mice for the allergens Fel d1 (cat hair), Der p1 (acarian:
Dermatophagoides pterissimus
) and Bet v1 (birch pollen) that the nasal, oral or subcutaneous administration of peptides carrying T epitopes of these allergens inhibits the activation of the specific T lymphocytes (16-18) and modulates the allergic reaction (16, 18).
Ideally, the desensitizing molecules should possess all the epitopes of the allergen and be free of reactivity toward the IgEs, so as to avoid the risks of accidents.
Several types of molecule are already being studied, including in the context of bee venom allergy and consist either of peptide fragments or of modified proteins.
Peptide Fragments
Using an empirical approach, the use of peptide fragments (19) to desensitize allergic patients has been proposed on several occasions as an alternative to conventional specific desensitization, including for bee venom allergy (20, 21).
These fragments generally no longer possess reactivity toward IgEs, but they may also have lost their capacity to be recognized by T lymphocytes.
More recently, allergen peptide fragments were chosen on the basis of their capacity to stimulate T lymphocytes in allergic patients (22).
In the case of the major bee venom allergen (API m1), fragments 50-69 and 83-97 have been described as being active during a study comprising a single patient (23).
In a study comprising forty patients (24), it is fragments 45-62 and 81-92 and 113-124 which proved to be active. These three fragments are only T epitopes for 25 to 45% of the patients and the authors do not exclude the existence of other epitopes (24, 25). These three peptides are undergoing clinical trial and appear to give encouraging results (22). Muller et al. (22) have used them to desensitize five allergic patients whose T lymphocytes proliferate in the presence of these peptides. No serious systemic effect was observed and the patients became tolerant to bee stings. This demonstrates the benefit of using peptides for desensitizing, but does not make it possible to extend the use of these peptides to other patients.
Another trial using peptides was set up for the cat allergen (Fel d1) (26). Several applications relating to peptides from ragweed (WO 93/21321; WO 96/13589), from Japanese cedar pollen (WO 93/01213; WO 94/01560) and from ryegrass pollen (WO 94/21675; WO 94/16068) have been filed.
All the peptides described in these applications were chosen on the basis of the stimulation of T lymphocytes in a group of allergic patients.
The approach followed by these various authors (23, 24 and 30) is based on cellular tests and not on binding tests. The results observed show that the active peptides vary according to the patients. In the latter three studies, the peptides containing the zone 80-90 are thos
Maillere Bernard
Menez Andre
Pouvelle Sandra
Texier Catherine
Chan Christina
Commissariat a l'Energie Atomique
DiBrino Marianne
LandOfFree
Peptides and proteins for desensitizing subjects allergic to... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Peptides and proteins for desensitizing subjects allergic to..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Peptides and proteins for desensitizing subjects allergic to... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3177760