The present invention relates to methods of using a composition of lactoferrin for the treatment of diabetes mellitus as manifested by a reduction in the levels of serum glucose, blood pressure, obesity, or glycosylated hemoglobin (HbA1c).

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to a method for modulating blood levels of glucose and insulin. The method of treatment involves administration of a lactoferrin composition.

An embodiment of the present invention comprises a method of modulating diabetes mellitus comprising the step of administering to a subject an effective amount of a lactoferrin composition, wherein the amount of the lactoferrin composition modulates at least one symptom of diabetes mellitus. Diabetes mellitus is non-insulin dependent diabetes mellitus or insulin dependent diabetes mellitus. The symptoms of diabetes mellitus can be selected from the group consisting of obesity, hyperglycemia, and increased insulin levels. Blood glucose is monitored by the level of glycosylated hemoglobin (HbA1c).

It is envisioned that the lactoferrin composition modulates the levels of insulin and/or blood glucose in the subject. In specific embodiments, the lactoferrin composition increases the levels of insulin and/or decreases the levels of blood glucose in the subject.

In further embodiments, the lactoferrin composition reduces the blood pressure in a subject suffering from diabetes mellitus induced high blood pressure. Still further, the lactoferrin composition reduces total body weight.

In certain embodiments of the present invention, the lactoferrin composition, which is dispersed in a pharmaceutically acceptable carrier, comprises lactoferrin or N-terminal lactoferrin variant in which at least the N-terminal glycine residue is truncated or substituted. The lactoferrin is mammalian lactoferrin, more particularly; the lactoferrin is human or bovine. Yet further, the lactoferrin is recombinant lactoferrin. In specific embodiments, the N-terminal lactoferrin variant comprises at least 1% of the lactoferrin composition, at least 5% of the lactoferrin composition, at least 10% of the lactoferrin composition, at least 25% of the lactoferrin composition, at least 50% of the lactoferrin composition or any range in between.

The lactoferrin composition can be formulated to be administered orally. Such formulations can comprise delayed release formulation so that the release of the composition occurs in the small intestine and/or in the large intestine.

Yet further, the lactoferrin composition of the present invention can be administered parenterally, for example, intravenously or intramuscularly.

In still further embodiments, the lactoferrin composition can be administered topically, for example, subcutaneously or dermally.

The amount of the composition that can be administered is about 1 .mu.g to about 20 g per day. More specifically, the amount of the composition that is administered is about 0.1 g to about 5 g per day.

In further embodiments, a metal chelator dispersed in a pharmaceutically acceptable carrier can also be administered with the lactoferrin composition. Preferred metal chelator include, but are not limited to ethylenediaminetetraacetic acid (EDTA) or [ethylenebis(oxyethylenenitrilo)] tetraacetic acid (EGTA). More preferably, the metal chelator is EDTA. The amount of EDTA that is administered is about 1 ng to about 1 g per day

It is also further envisioned that the present method can be used in combination with an antidiabetic drug.

Another embodiment of the present invention is a method of treating a subject susceptible to diabetes mellitus comprising the step of administering to the subject an effective amount of a lactoferrin composition, wherein the amount reduces the incidence of diabetes mellitus.

Still further, another embodiment is a method of reducing blood glucose in a subject suffering from diabetes mellitus comprising the step of administering to the subject an effective amount of a lactoferrin composition, wherein the amount of the lactoferrin composition modulates blood glucose.

Another embodiment is a method of modulating blood insulin in a subject suffering from diabetes mellitus comprising the step of administering to the subject an effective amount of a lactoferrin composition, wherein the amount of the lactoferrin composition modulates blood insulin. Modulating blood insulin results in an increase in blood insulin and/or a decrease in blood insulin.

The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized that such equivalent constructions do not depart from the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Lactoferrin

The lactoferrin used according to the present invention can be obtained through isolation and purification from natural sources, for example, but not limited to mammalian milk. The lactoferrin is preferably mammalian lactoferrin, such as bovine or human lactoferrin. In preferred embodiments, the lactoferrin is produced recombinantly using genetic engineering techniques well known and used in the art, such as recombinant expression or direct production in genetically altered animals, plants or eukaryotes, or chemical synthesis. See, e.g., U.S. Pat. Nos. 5,571,896; 5,571,697 and 5,571,691, which are herein incorporated by reference.

In certain aspects, the present invention provides lactoferrin variants having enhanced biological activities over natural LF and or rLF, e.g., the ability to stimulate and/or inhibit cytokines or chemokines. In particular, the invention provides variants of lactoferrin from which at least the N-terminal glycine residue has been substituted and/or truncated. The N-terminal lactoferrin variants may occur naturally or may be modified by the substitution or deletion of one or more amino acids.

The deletional variants can be produced by proteolysis of lactoferrin and/or expression of a polynucleotide encoding a truncated lactoferrin as described in U.S. Pat. No. 6,333,311, which is incorporated herein by reference.

Substitutional variants or replacement variants typically contain the exchange of one amino acid for another at one or more sites within the protein. Substitutions can be conservative, that is, one amino acid is replaced with one of similar shape and charge. Conservative substitutions are well known in the art and include, for example, the changes of: alanine to serine; arginine to lysine; asparagine to glutamine or histidine; aspartate to glutamate; cysteine to serine; glutamine to asparagine; glutamate to aspartate; glycine to proline; histidine to asparagine or glutamine; isoleucine to leucine or valine; leucine to valine or isoleucine; lysine to arginine; methionine to leucine or isoleucine; phenylalanine to tyrosine, leucine or methionine; serine to threonine; threonine to serine; tryptophan to tyrosine; tyrosine to tryptophan or phenylalanine; and valine to isoleucine or leucine.

In making such changes, the hydropathic index of amino acids may be considered. The importance of the hydropathic amino acid index in conferring interactive biologic function on a protein is generally understood in the art (Kyte and Doolittle, 1982). It is accepted that the relative hydropathic character of the amino acid contributes to the secondary structure of the resultant protein, which in turn defines the interaction of the protein with other molecules, for example, enzymes, substrates, receptors, DNA, antibodies, antigens, and the like.

Each amino acid has been assigned a hydropathic index on the basis of their hydrophobicity and charge characteristics (Kyte and Doolittle, 1982), these are: isoleucine (+4.5); valine (+4.2); leucine (+3.8); phenylalanine (+2.8); cysteine/cystine (+2.5); methionine (+1.9); alanine (+1.8); glycine (-0.4); threonine (-0.7); serine (-0.8); tryptophan (-0.9); tyrosine (-1.3); proline (-1.6); histidine (-3.2); glutamate (-3.5); glutamine (-3.5); aspartate (-3.5); asparagine (-3.5); lysine (-3.9); and arginine (-4.5).

It is known in the art that certain amino acids may be substituted by other amino acids having a similar hydropathic index or score and still result in a protein with similar biological activity, e.g., still obtain a biological functionally equivalent protein. In making such changes, the substitution of amino acids whose hydropathic indices are within .+-.2 is preferred, those that are within .+-.1 are particularly preferred, and those within .+-.0.5 are even more particularly preferred.

It is also understood in the art that the substitution of like amino acids can be made effectively on the basis of hydrophilicity. U.S. Pat. No. 4,554,101, incorporated herein by reference, states that the greatest local average hydrophilicity of a protein, as governed by the hydrophilicity of its adjacent amino acids, correlates with a biological property of the protein. As detailed in U.S. Pat. No. 4,554,101, the following hydrophilicity values have been assigned to amino acid residues: arginine (+3.0); lysine (+3.0); aspartate (+3.0.+-.1); glutamate (+3.0.+-.1); serine (+0.3); asparagine (+0.2); glutamine (+0.2); glycine (0); threonine (-0.4); proline (-0.5.+-.1); alanine (-0.5); histidine -0.5); cysteine (-1.0); methionine (-1.3); valine (-1.5); leucine (-1.8); isoleucine (-1.8); tyrosine (-2.3); phenylalanine (-2.5); tryptophan (-3.4).

Still further, it is understood that an amino acid can be substituted for another having a similar hydrophilicity value and still obtains a biologically equivalent and immunologically equivalent protein. In such changes, the substitution of amino acids whose hydrophilicity values are within .+-.2 is preferred, those that are within .+-.1 are particularly preferred, and those within .+-.0.5 are even more particularly preferred.

Thus, in the present invention, substitutional variants or replacement can be produced using standard mutagenesis techniques, for example, site-directed mutagenesis as disclosed in U.S. Pat. Nos. 5,220,007; 5,284,760; 5,354,670; 5,366,878; 5,389,514; 5,635,377; 5,789,166, and 6,333,311, which are incorporated herein by reference. It is envisioned that at least the N-terminal glycine amino acid residue can be replaced or substituted with any of the twenty natural occurring amino acids, for example a positively charged amino acid (arginine, lysine, or histidine), a neutral amino acid (alanine, asparagine, cysteine, glutamine, glycine, isoleucine, leucine, methionine, phenylaline, proline, serine, threonine, tryptophan, tyrosine, valine) and/or a negatively charged amino acid (aspartic acid or glutamic acid). Still further, it is contemplated that any amino acid residue within the range of N1 to N16 can be replaced or substituted. It is envisioned that at least up to 16 of the N-terminal amino acids residues can be replaced or substituted as long as the protein retains it biological and/or functional activity, which is stimulating the production of various cytokines (e.g., IL-18, MIP-3.alpha., GM-CSF or IFN-.gamma.), by inhibiting various cytokines, (e.g., IL-2, IL-4, IL-5, IL-6, IL-10, or TNF-.alpha.), and/or effecting parameters relating to diabetes mellitus including blood levels of glucose or insulin (e.g., decreasing, reducing, inhibiting or abrogating high glucose, reducing total body weight, reducing glycosylated hemoglobin (HbA1c), reducing blood pressure or modulating blood insulin levels). Thus, the N-terminal lactoferrin variants of the present invention are considered functional equivalents of lactoferrin.

In terms of functional equivalents, it is well understood by the skilled artisan that, inherent in the definition of a "biologically functional equivalent" protein is the concept that there is a limit to the number of changes that may be made within a defined portion of the molecule while retaining a molecule with an acceptable level of equivalent biological activity and/or enhancing the biological activity of the lactoferrin molecule. Biologically functional equivalents are thus defined herein as those proteins in which selected amino acids (or codons) may be substituted. Functional activity is defined as the ability of lactoferrin to stimulate or inhibit various cytokines or chemokines and/or effect parameters relating to diabetes mellitus including blood levels of glucose or insulin, for example decreasing, reducing, inhibiting or abrogating high glucose, reducing total body weight, reducing glycosylated hemoglobin (HbA1c), reducing blood pressure or modulating blood insulin levels.

Still further, the N-terminal amino acid residues can be substituted with a modified and/or unusual amino acids. A table of exemplary, but not limiting, modified and/or unusual amino acids is provided herein below -- see Original Patent.

The presence and the relative proportion of an N-terminal lactoferrin variants (deletions and/or substitutions) in a preparation of lactoferrin (lactoferrin composition) may be done by determination of the N-terminal amino acid sequence by the process of Edman degradation using standard methods. A relative proportion of N-terminal lactoferrin variant comprises at least 1% of the lactoferrin composition, at least 5% of the lactoferrin composition, at least 10% of the lactoferrin composition, at least 25% of the lactoferrin composition, at least 50% of the lactoferrin composition or any range in between.

In this method, the protein is reacted with phenylisothiocyanate (PITC), which reacts with the amino acid residue at the amino terminus under basic conditions to form a phenylthiocarbamyl derivative (PTC-protein). Trifluoroacetic acid then cleaves off the first amino acid as its anilinothialinone derivative (ATZ-amino acid) and leaves the new amino terminus for the next degradation cycle.

The percentage of N-terminal lactoferrin variant may also be done more precisely by using a Dansylation reaction. Briefly, protein is dansylated using Dansyl chloride reacted with the protein in alkaline conditions (pH 10). Following the Dansylation, the reaction mixtures are dried to pellets, then completely hydrolyzed in 6N HCl. The proportion of N-terminal amino acids are identified by RP HPLC using an in-line fluorometer in comparison with standards made up of known dansylated amino acids.

C. Pharmaceutical Compositions

The present invention is drawn to a composition comprising a lactoferrin composition that is dispersed in a pharmaceutical carrier. The lactoferrin that is contained in the composition of the present invention comprises lactoferrin or an N-terminal lactoferrin variant in which at least the N-1 terminal glycine residue is truncated or substituted. More specifically, the N-terminal lactoferrin variant comprises at least 1% of the composition, at least 5% of the composition, at least 10% of the composition, at least 25% of the composition, at least 50% of the composition or any range in between.

Yet further, the composition comprises lactoferrin in combination with a metal chelator dispersed in a pharmaceutical carrier. Thus, the present invention is drawn to a lactoferrin composition with or without a metal chelator that is dispersed in a pharmaceutical carrier. One of skill in the art understands that both compositions (e.g., lactoferrin alone or lactoferrin in combination with a metal chelator) are within the scope of the present invention and can be used interchangeably depending upon the type of response that is desired. It is envisioned that the addition of a metal chelator to the lactoferrin composition enhances the sequestering of metal ions and thus strengthens the immune system or enhances the effect of lactoferrin.

Metal chelators that can be used in combination with lactoferrin, include the divalent metal chelators, for example, ethylenediaminetetraacetic acid (EDTA), [ethylenebis(oxyethylenenitrilo)] tetraacetic acid (EGTA), 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), hydroxyethlene triamine diacetic acid, (HEDTA) or any salts thereof. More preferably, EDTA is used in combination with lactoferrin.

Administration of the lactoferrin compositions according to the present invention will be via any common route, orally, parenterally or topically. Exemplary routes include, but are not limited to oral, nasal, buccal, rectal, vaginal or topical, intradermal, transdermal, subcutaneous, intramuscular, intraperitoneal, intravenous, or intraarterial. Such compositions would normally be administered as pharmaceutically acceptable compositions as described herein.

Further in accordance with the present invention, the composition of the present invention suitable for administration is provided in a pharmaceutically acceptable carrier with or without an inert diluent. The carrier should be assimilable and includes liquid, semi-solid, e.g., pastes, or solid carriers. Except insofar as any conventional media, agent, diluent or carrier is detrimental to the recipient or to the therapeutic effectiveness of the composition contained therein, its use in administrable composition for use in practicing the methods of the present invention is appropriate. Examples of carriers or diluents include fats, oils, water, saline solutions, lipids, liposomes, resins, binders, fillers and the like, or combinations thereof.

In accordance with the present invention, the composition is combined with the carrier in any convenient and practical manner, e.g., by solution, suspension, emulsification, admixture, encapsulation, absorption and the like. Such procedures are routine for those skilled in the art.

In a specific embodiment of the present invention, the composition is combined or mixed thoroughly with a semi-solid or solid carrier. The mixing can be carried out in any convenient manner such as grinding. Stabilizing agents can be also added in the mixing process in order to protect the composition from loss of therapeutic activity, e.g., denaturation in the stomach. Examples of stabilizers for use in an the composition include buffers, amino acids such as glycine and lysine, carbohydrates such as dextrose, mannose, galactose, fructose, lactose, sucrose, maltose, sorbitol, mannitol, etc., proteolytic enzyme inhibitors, and the like. Yet further, it is envisioned that divalent metal chelators, for example EDTA, can also be used to stabilize the composition of the present invention. More preferably, for an orally administered composition, the stabilizer can also include antagonists to the secretion of stomach acids.

The composition for oral administration which is combined with a semi-solid or solid carrier can be further formulated into hard or soft shell gelatin capsules, tablets, or pills. More preferably, gelatin capsules, tablets, or pills are enterically coated. Enteric coatings prevent denaturation of the composition in the stomach or upper bowel where the pH is acidic. See, e.g., U.S. Pat. No. 5,629,001. Upon reaching the small intestines, the basic pH therein dissolves the coating and permits the lactoferrin composition to be released and absorbed by specialized cells, e.g., epithelial enterocytes and Peyer's patch M cells.

In another embodiment, a powdered composition is combined with a liquid carrier such as, e.g., water or a saline solution, with or without a stabilizing agent.

Further, the composition for topical administration which is combined with a semi-solid carrier can be further formulated into a gel ointment. A preferred carrier for the formation of a gel ointment is a gel polymer. Preferred polymers that are used to manufacture a gel composition of the present invention include, but are not limited to carbopol, carboxymethyl-cellulose, and pluronic polymers. Gel polymers prevent denaturation of the composition in the open skin by serum proteases.

The amount of lactoferrin in the present invention may vary from about 0.1 .mu.g to about 100 g of lactoferrin per day. More preferably, lactoferrin is administered in the range of 1 .mu.g to 20 g of lactoferrin per day. Yet further, in specific embodiments the amount of lactoferrin that is administered can be in the range of about 0.1 g to about 5 g. The lactoferrin may comprise lactoferrin or an N-terminal lactoferrin variant in which at least the N-1 terminal glycine residue is truncated and/or substituted.

More preferably, the composition of the present invention also contains metal chelators, for example, but not limited to ethylenediaminetetraacetic acid (EDTA), [ethylenebis (oxyethylenenitrilo)]tetraacetic acid (EGTA), 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), hydroxyethlene triamine diacetic acid, (HEDTA) or salts thereof. The amount of the metal chelator in the composition may vary from about 1 ng to about 20 g. A preferred metal chelator is EDTA.

Upon formulation, solutions are administered in a manner compatible with the dosage formulation and in such amount as is therapeutically effective to result in an improvement or remediation of the symptoms. The formulations are easily administered in a variety of dosage forms such as ingestible solutions, drug release capsules and the like. Some variation in dosage can occur depending on the condition of the subject being treated. The person responsible for administration can, in any event, determine the appropriate dose for the individual subject. Moreover, for human administration, preparations meet sterility, general safety and purity standards as required by FDA Office of Biologics standards.

D. Treatment or Prophylaxis of Diabetes Mellitus

In accordance with the present invention, the composition provided in any of the above-described pharmaceutical carriers is administered to a subject who has experienced or is at high risk of having diabetes mellitus. Thus, it is envisioned that the lactoferrin composition of the present invention may be administered to a subject to regulate diabetes mellitus. The lactoferrin composition modulates at least one symptom of diabetes mellitus, for example, decrease blood glucose or modulate blood insulin levels.

Risk factors for type I diabetes include islet-cell antibodies and those of type 2 or gestational diabetes include inactivity, obesity, siblings with diabetes, and history of diabetes during pregnancy. One of skill in the art can determine the patients who would potentially benefit from a therapeutic agent that would reduce circulating levels of glucose. One of skill in the art can determine the therapeutically effective amount of the composition to be administered to a subject based upon several considerations, such as local effects, pharmacodynamics, absorption, metabolism, method of delivery, age, weight, disease severity and response to the therapy.

Oral administration of the composition includes oral, buccal, enteral or intragastric administration. It is also envisioned that the composition may be used as a food additive. For example, the composition is sprinkled on food or added to a liquid prior to ingestion.

In further embodiments, the composition is administered in conjunction with an antacid. Thus, an antacid is administered prior or substantially simultaneously with or after oral administration of the composition. The administration of an antacid just prior or immediately following the administration of the composition may help to reduce the degree of inactivation of the lactoferrin in the digestive tract. Examples of appropriate antacids include, but are not limited to, sodium bicarbonate, magnesium oxide, magnesium hydroxide, calcium carbonate, magnesium trisilicate, magnesium carbonate, and alumin hydroxide gel.

In addition to oral administration, the lactoferrin composition can also be administered parenterally (i.e., intramuscular, intraperitoneal, intravenous, intraarterial) or topically (i.e., intradermal, transdermal, or subcutaneous).

In a preferred embodiment of the present invention, the composition is administered in an effective amount to decrease, reduce, inhibit or abrogate high glucose, or to reduce total body weight, glycosylated hemoglobin (HbA1c), or blood pressure or to modulate blood insulin levels. In the case of a diabetic condition, successful reduction of hyperglycemia by the lactoferrin composition may be manifested by the fasting plasma glucose level falling below 126 mg/dL, the 2-hour plasma glucose level during an oral glucose tolerance test (OGTT) falling below below 200 mg/dL, or if a random plasma glucose determination reading below 200 mg/dL in a symptomatic individual. In the case of a pre-diabetic condition, a successful reduction of hyperglycemia by the lactoferrin composition may be manifested by the fasting plasma glucose falling below 110 mg/dL and/or the 2-hour plasma glucose on the OGTT falling below between 140 mg/dL. The amount of lactoferrin in the composition may vary from about 0.1 .mu.g to about 100 g, more preferably, from about 1 .mu.g to about 20 g, or any range therebetween. In specific embodiments, the composition that is administered contains the range of 0.1 g to 5 g of lactoferrin per day.

Glycohemoglobin (or glycosylated hemoglobin) is measured to monitor or accurately record blood glucose levels, and it is not influenced by acute changes in blood glucose or by the interval since the last meal. Glycohemoglobin is formed when glucose reacts non-enzymatically with the hemoglobin A molecule and is composed of several fractions, the major one being HbA1c. Total glycohemoglobin (HbA1) and HbA1c (expressed as the percentage of total hemoglobin) vary in proportion to the average level of glucose over the lifespan of the red blood cell (RBC), thereby providing an index of glycemic control.

Further aspects of the invention include reducing blood glucose in a patient suffering from diabetes mellitus by administering to a subject an effective amount of a lactoferrin composition such that the amount of the lactoferrin composition modulates blood glucose. The blood glucose is monitored by the level of glycosylated hemoglobin (HbA1c).

Another aspect is a method of modulating blood insulin in a patient suffering from diabetes mellitus by administering to a subject an effective amount of a lactoferrin composition such that the amount of the lactoferrin composition modulates blood insulin. Modulating blood insulin includes reducing or maintaining blood insulin levels or increasing blood insulin levels.

Modulating blood insulin levels in the present invention includes increasing blood insulin levels in insulin-dependent diabetes (Type I) or decreasing or maintaining insulin levels in non-insulin-dependent diabetes (Type II).

Treatment regimens may vary as well, and often depend on the health and age of the patient. Obviously, certain types of disease will require more aggressive treatment, while at the same time, certain patients cannot tolerate more taxing regimens. The clinician will be best suited to make such decisions based on the known efficacy and toxicity (if any) of the therapeutic formulations.

In specific embodiments, the composition is given in a single dose or multiple doses. The single dose may be administered daily, or multiple times a day, or multiple times a week, or monthly or multiple times a month. In a further embodiment, the lactoferrin is given in a series of doses. The series of doses may be administered daily, or multiple times a day, weekly, or multiple times a week, or monthly, or multiple times a month.

E. Combination Treatments

In order to increase the effectiveness of administration of the composition of the present invention, it is desirable to combine the lactoferrin compositions with an additional agent. For example, known diabetes agents are used in combination with the composition of the present invention. Exemplary agents known to treat high glucose or insulin sulfonylureas, biguanides, alpha-glucosidase, thiazolidinedione, meglitinide, and amino acid D-phenylalanine derivative. Other antidiabetic agents may also include, a weight loss regimen and/or a diet alteration.

The composition of the present invention may precede, be co-current with and/or follow the other agent(s) by intervals ranging from minutes to weeks. In embodiments where the composition of the present invention, and other agent(s) are applied separately to a cell, tissue or organism, one would generally ensure that a significant period of time did not expire between the time of each delivery, such that the composition and agent(s) would still be able to exert an advantageously combined effect on the cell, tissue or organism.
 

Claim 1 of 24 Claims

1. A method of treating diabetes mellitus comprising administering to a subject an effective amount of a lactoferrin composition having an N-terminal lactoferrin variant in combination with an effective amount of an antidiabetic drug, wherein the N-terminal lactoferrin variant retains the biological activity of full length lactoferrin, and wherein the effective amount of said lactoferrin composition and the effective amount of said antidiabetic drug decrease blood levels of glucose and insulin thereby treating diabetes mellitus.

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