MXPA99011187A - Use of leptin antagonists for the treatment of diabetes - Google Patents

Abstract

The use of an antagonist of leptin for the manufacture of a medicament for the treatment of disorders resulting from deficiencies in insulin secretion, hyperglycaemia and insulin resistance.

Description

USE OF LEPTINE ANTAGONISTS FOR THE TREATMENT OF DIABETES DESCRIPTIVE MEMORY The invention relates to a novel use, in particular to a use for the treatment of diabetes and complications thereof. It is known that non-insulin-dependent diabetes (NIDDM) is caused by insulin resistance (particularly in skeletal muscle, adipose tissue and liver) and inadequate insulin secretion from the beta cells of the Islets of Langerhans in the pancreas. Thus, despite hyperinsulinemia, there is insufficient insulin to compensate for insulin resistance and to keep blood glucose within the desirable range. Pelleymounter et al. (Science, 1995, 269, 540-543) have reported that the ob polypeptide or "leptin" reduces both plasma insulin levels and glucose levels in the genetically obese ob / ob mouse. U.S. Patent Application No. 2292382 relates inter alia to polypeptides, OB polypeptides, and antagonists thereof and their use to modulate body weight. The definitions of GB 2292382 are incorporated herein by reference.

It has been observed that recombinant leptin directly inhibits the release of insulin from the isolated islets and the prefused pancreas of the mouse ob / ob. Therefore, it is indicated that a leptin antagonist is useful to increase insulin secretion and thereby assist in the control of blood glucose levels. It has also been shown that leptin inhibits glycogen synthesis and basal level stimulated by insulin in soleus muscle isolated from compulsive ob / ob mice. Therefore, it is also indicated that a leptin antagonist is useful to increase the utilization of glucose and the action of insulin to increase the utilization of glucose. Therefore, antagonists are indicated for direct use in the treatment of disorders resulting from deficiencies in insulin secretion and action and hypergiukaemia, such as non-insulin dependent diabetes. In addition, since hypergiukaemia is believed to lead to many of the long-term complications of diabetes, an antagonist that increases insulin secretion and aids in the control of blood glucose may be useful for the treatment of complications. diabetics, such as retinopathy, nephropathy and angiopathy. Also, the invention provides the use of a leptin antagonist for the treatment of disorders that result from deficiencies in insulin secretion and hypergiukaemia, such as non-insulin dependent diabetes (NIDDM). In another aspect, the use of a leptin antagonist is provided for the manufacture of a medicament for the treatment of disorders that result from deficiencies in insulin secretion and hypergiukaemia, such as non-insulin dependent diabetes (NIDDM). . Suitable antagonists of leptin are described in GB2292382 and can be prepared according to the methods described therein. Particular antagonists include protein antagonists. Particular antagonists include non-protein antagonists, especially small organic molecule antagonists. The present invention also encompasses a method for the treatment of disorders resulting from deficiencies in insulin secretion and hypergiukaemia, such as non-insulin dependent diabetes (NIDDM), in a human or non-human mammal, which method comprises administration to a human or non-human mammal in need of such treatment, a non-toxic, pharmaceutically acceptable, effective amount of a leptin antagonist. The present invention also encompasses a pharmaceutical composition comprising a leptin antagonist, or a pharmaceutically acceptable derivative thereof, and a pharmaceutically acceptable carrier. The particular compositions of the invention are those that were used for the treatment of disorders that resulted from deficiencies in insulin secretion and hypergiukaemia, such as non-insulin dependent diabetes (NIDDM).

Suitable pharmaceutically acceptable carriers are as dictated by conventional practice those described in GB2292382 or in the international patent application, publication number WO 94/01420. The compositions of the invention are prepared in accordance with conventional practice, as described in the patent applications mentioned above. The doses of the antagonists can be determined in accordance with conventional methodology such as that described in the aforementioned patent applications. The following is a brief description of the figures (Figures 1-5 and Table 1) of the application: Figure 1 and Table 1 show the effect of leptin (100nM) on basal insulin secretion from the pre-formed pancreas of ob mice; Figure 2 shows the effect of leptin (100 nmol / l) on insulin secretion stimulated by glucose (16.7 mmol / l) from ob / ob islets; Figure 3 shows the dose dependence of inhibitory effects of recombinant leptin on insulin secretion stimulated by glucose (16.7 mmol / l) from pancreatic islets isolated from ob / ob mice; Figure 4 shows the effect of leptin on the synthesis of glycogen in soleus muscle isolated from ob / ob mice; and Figure 5 shows the effect of leptin on the synthesis of glycogen in soleus muscle isolated from ob / ob mice. Lee et al (Nature, 1995,379,632-635) have shown that there are a number of forms of the leptin receptor. If the islet receptor (s) differs in nature or proportions from that of other tissues, a particularly useful antagonist may be one that antagonizes the action of leptin on the islet and / or skeletal muscle receptor, but does not antagonize other leptin receptors (for example in the hypothalamus) and thereby exacerbating insulin resistance. Mutations in the mouse ob gene (J. Hered, 41, 317-318) 1950) and the db gene (Science 153, 1127-1128 (1996)) result in obesity and non-insulin dependent diabetes. The product of the ob gene, leptin, is expressed exclusively in adipose tissue (Nature (Lond.), 372, 425-432 (1994)) and it has been shown that daily injections of recombinant leptin inhibit the consumption of food and reduce body weight and the fat mass in ob / ob mice (Science 269, 543-546 (1995), Science 269, 540-543 (1995), Science 269, 546-549 (1995)). Such treatment also results in a reduction in hyperinsulinemia (Science 269, 540-543 (1995)). Recently, the gene encoding the receptor for the ob gene has been identified (Cell 83, 1263-1271 (1995)). The leptin receptor has many variables alternatively spliced. One of these spliced variables is expressed at a high level in the hypothalamus, and is believed to be a functional receptor in the regulation of energy balance. Abnormally spliced in db / db C57B1 / KSJ mice (Nature (Lond.) 379, 622-635 (1996); Cell 84, 491-495 (1996); Science 271, 994-996 (1996)). that the cytoplasmic region is lost, leading to defective translation of a signal. It is reported that, in addition to the hypothalamus, the predicted functional leptin ob-Rb receptor is expressed in several tissues, including pancreatic islets, in ob / ob mice. In addition, recombinant leptin directly inhibits the release of insulin from the isolated islets and the preformed pancreas of the ob / ob mouse, and inhibits glycogen and basal level synthesis stimulated by insulin in soleus muscle isolated from ob / ob mice, demonstrating that Leptin has both central and peripheral actions. The product of the diabetic gene (db) in mice has been identified as the receptor for leptin. At least six alternately spliced forms of the leptin message have been identified (Nature (Lond.) 379, 622-635 (1996)). One of these, Ob-Rb, has an extensive intracellular region that contains a motif of the Box 2 sequence, which is required for the binding of JAK protein kinases and is thought to encode the functional receptor. The short antisense oligodeoxynucleotide probes (Trayhurn et al, Biochem. Soc. Trans. Vol 23 page 4945, 1995) 30-34-mer, were designed to hybridize with different domains in the mRNA sequence of the mouse leptin receptor and they were used to detect any expression of all transcripts of the leptin receptor or to detect only the long form of the leptin receptor Ob / Rb. Each sequence of the oligonucleotide probe was unique to the leptin receptor and had no important homology to any other known sequence. Expression in slender + / + mice of total leptin receptor mRNA was detected in the hypothalamus, kidneys, lung, liver, entire pancreas, brain, soleus muscle and in the spleen but not in white adipose tissue, in the pituitary or in the heart. The leptin receptor mRNA standardized for the levels of poly (A) mRNA was overexpressed in ob / ob mice related to the slender counterparts. However, there were specific differences in tissue in overexpression. Thus, the hypothalamus showing the highest expression level in slender mice was overexpressed twice in ob / ob mice. In the kidney, the total leptin mRNA was overexpressed 4 times but in some other tissues that had lower expression of total leptin mRNA in slender mice, the total leptin mRNA was overexpressed up to 10-fold in ob / ob mice. Northern blot analysis of the hypothalamus tested with a 34-mer corresponding to bases 3329-3363, which are part of the intracellular loops present only in long form of leptin receptor Ob-Rb, gave a single acute band. This contrasted with multiple bands when the blot was tested with 33-mer corresponding to bases 1877-1910, which is a sequence common to all known spliced variables of the leptin receptor. Molecular weight markers indicated that 34-mer hybridized to an mRNA fragment of approximately 3400 p.b. consistent with the putative functional leptin receptor. This was expressed at a high level in the hypothalamus, according to recent studies by Lee et al. (Nature (Lond.) 379, 622-635 (1996)). In addition, the hypothalamus of the ob / ob mice showed overexpression twice related to the + / + mice. The leptin receptor Ob-Rb also occurs (in overexpression related to the slender + / + mice) in the liver, kidney and lung but not in the entire brain, heart, soleus or pituitary muscle. The discovery of relative overexpression of leptin Ob-Rb in ob / ob mice related to slender + / + mice is consistent with the findings of many workers (Science 269, 540-543 (1995)).; Proc. Nati, Acad. Sci., USA 93, 1726-1730 (1996)) that recombinant leptin is more effective in reducing food intake and body weight in ob / ob mice. There is also the possibility that leptin regulates the expression of its receptor. This could result in leptin-resistant states and may explain the relative lack of activity of recombinant leptin in obesity induced by diets (Science 269, 540-543 (1995)). Using the slot-blot technique, no expression of the long form of the leptin receptor was detected throughout the pancreas of slender + / + mice or ob / ob mice. However, a strong signal was obtained using mRNA from the pancreatic islets of the ob / ob mouse. Previous studies have shown that daily intraperitoneal injections of recombinant leptin for 28 days produced a significant dose-dependent reduction in serum insulin and blood glucose in ob / ob mice but not in slender mice (Science 269, 540- 543 (1995)). By giving the elevated expression of the long form of the leptin receptor, which is the putative functional receptor, in pancreatic islets of ob / ob mice, we decided to examine the functional response in insulin secretion using the pre-formed pancreas of the ob / ob mouse ( figure 1, table 1). Leptin (100nM) produced an immediate reduction in insulin release from the isolated pancreas. The action of leptin in the preparation of the pre-fused pancreas can be direct in the islets or by means of the release of an additional mediator from the vasculature. To clarify this, the effect of leptin on insulin that is released from pancreatic islets isolated from mouse ob / ob was determined. Leptin (100nM) completely inhibited the stimulatory effect of 16.7mM of glucose on insulin release in isolated islets from mice fasted overnight (Figure 2). The inhibitory effect of leptin was related to the dose on the scale of 1-100nM (figure 3). Also, leptin (10 nm) inhibited glucose-stimulated insulin secretion by means of islets from wild-type mice, however leptin (100nM) had no effect on insulin secretion by islets of mice ob / ob. To evaluate the possibility that leptin could directly inhibit glucose uptake and insulin action, the incorporation of [14C] -glucose into glycogen was measured in isolated intact sole muscles of ob / ob mice weighing 4- 6 milligrams using the method of Challiss et al. (Biochemícal Pharmacology, 1988, 37, 947-950). Recombinant murine leptin at 100nM inhibited glycogen synthesis in the soleus muscle (Figure 4), with 35% inhibition at baseline (PO.01), and 28%, 30% and 45% at low insulin concentrations (10 , 50 and 100uU / ml respectively, P <0.05). The maximum response for insulin (10,000uU7ml) was not significantly affected by leptin. The effects of low concentrations of leptin (1 and 10nM) were examined in the absence of insulin and in the presence of 100uU7ml of insulin. 10nM of leptin caused significant inhibition in glycogen synthesis and basal level stimulated by insulin (32% and 35% respectively, P <0.05), where 1 nM of leptin did not have an important effect (figure 5). Obesity is the most common eating disorder in Western society and in many developing countries. It is strongly associated with non-insulin-dependent diabetes. It has been assumed to a large extent that the bases of this association are related to the increase in insulin resistance that occurs with the adiposity that develops. It is believed that insulin resistance results in glucose intolerance but it is commonly believed that the development of non-insulin dependent diabetes requires additional independent development of a pancreatic lesion. Initial studies using the recombinant leptin infusion for ob / ob mice and slender counterparts suggested that the main action of leptin was to control the appetite possibly through a suppression of central NPY release (Nature (Lond.) 337, 530-532 (1995)). However, a more recent study that included a group of ob / ob mice that consumed the same amount of food as mice infused with leptin, showed that leptin had important metabolic actions (Proc. Nati, Acad. Sci., USA 93, 1726-1730 (1996)). Infusion of leptin to ob / ob mice resulted in significantly lower body weight and weight in the fat pool relative to mice fed in pairs. However, the most drastic difference between mice infused with leptin and animals fed in pairs was found in serum insulin concentration. Those fed in pairs reduced the insulin concentration from 30.6 ± 6.2 mg / ml to 14.2 + 4.2 mg / ml. In mice infused with leptin, the insulin concentration 0.09 ± 0.08 ng / ml was not significantly different from that of the slender animals (Proc Nati, Acad. Sci., USA 93, 1726-1730 (1996)). The present study demonstrates that the spliced variable of the leptin receptor that codes for the functional receptor is present in pancreatic islets of ob / ob mice, and that leptin will directly inhibit the secretion of basal insulin in the pre-fused pancreas and insulin stimulated by glucose released by the isolated islets of the ob / ob mouse. These data suggest for the first time that the overproduction of leptin after an excess of adiposity can directly modify the secretion of insulin and may be involved in the development of the diabetic syndrome. These data also suggest that overproduction of leptin related to obesity may be one of a large number of factors responsible for inducing insulin resistance in obesity. Also, in a further particular aspect, the present invention provides the use of a leptin antagonist for the treatment of insulin resistance, especially that related to obesity. In addition, the use of a leptin antagonist is provided for the manufacture of a medicament for the treatment of insulin resistance, especially that related to obesity. A method is also provided for the treatment of insulin resistance, especially that which is related to obesity, in a human or non-human mammal, whose method comprises administration to the human or non-human mammal in need of said treatment, a non-toxic, pharmaceutically acceptable, effective amount of a leptin antagonist. A further particular pharmaceutical composition of the invention is therefore a pharmaceutical composition useful for the treatment of insulin resistance, especially that which is related to obesity. In addition to the pancreatic islets, the long form of the leptin receptor in the liver, kidney and lung has also been detected. The functional effects of leptin in these tissues are unknown at present. However, Levin et al. (Proc. Nati, Acad. Sci., USA 93, 1726-1730 (1996)) discovered that the hepatic glycogen content was significantly reduced in the ob / ob mice infused with leptin but not in the animals fed in pairs. Together with the current data, these findings suggest that feptin can directly affect e! hepatic glycogen metabolism. In summary, the results of the present show molecular biology and functional evidence for leptin that has widely disseminated peripheral metabolic activity as well as a central action in food consumption. The descriptions of the aforementioned references including the patent applications GB2292382 and WO 94/01420 are incorporated herein by reference. The following figures and the table show the invention without limiting it in any way.

TABLE 1 0-15 min: Stabilization period 16-30 min: Period of treatment (PBS or Leptin) AUC: area under the curve% change: means 16-30 min vs means 0-15 min Results are means + SEM (n = 4.5). * P < 0.05 (non-paired tests)

Claims (5)

NOVELTY OF THE INVENTION CLAIMS

1 .- The use of a leptin antagonist for the manufacture of a medicament for the treatment of disorders resulting from deficiencies in insulin secretion, hypergiukaemia and insulin resistance

2. The use according to claim 1, in where the disorder is non-insulin dependent diabetes (NIDDM).

3. The use according to claim 1, wherein the treatment of insulin resistance is related to obesity.

4. A pharmaceutical composition for the treatment of disorders resulting from deficiencies of insulin secretion, hypergiukaemia and insulin resistance comprising a leptin antagonist, or a pharmaceutically acceptable derivative thereof, and a pharmaceutically acceptable carrier.

5. The use according to any of claims 1 to 3, wherein the leptin antagonist is a small organic molecule antagonist.