WO2012074676A2

WO2012074676A2 - Glp-1 agonists, dpp-4 inhibitors, compositions, and uses related thereto

Info

Publication number: WO2012074676A2
Application number: PCT/US2011/059577
Authority: WO
Inventors: Nitika Gupta
Original assignee: Emory University
Priority date: 2010-11-09
Filing date: 2011-11-07
Publication date: 2012-06-07
Also published as: WO2012074676A3

Abstract

This disclosure relates to GLP-1 pathway agonists and DPP -2 inhibitors and uses related thereto. In certain embodiments, the disclosure relates to methods of improving organ transplants and preventing ischemic injury. In certain embodiments the disclosure relates to organ, cell, or tissue preservation solutions comprising compositions disclosed herein.

Description

GLP-1 AGONISTS, DPP-4 INHIBITORS, COMPOSITIONS, AND USES

RELATED THERETO

CROSS REFERENCE

This application claims priority to U. S . Provisional Application Number 61/411,518 filed November 9, 2010 hereby incorporated by reference in its entirety.

BACKGROUND

Obesity is increasing in epidemic proportions and concomitantly there is a significant increase in the incidence of non-alcoholic fatty liver disease (NAFLD). NAFLD and NASH (non-alcoholic steatohepatitis) affect up to 30 million people in the United States, of which over 600,000 are likely to have cirrhosis. NAFLD can frequently progress to end stage liver disease, which is predicted to surpass hepatitis C as the leading cause for liver

transplantation. In addition a steatotic liver is also more susceptible to injury resulting from ischemia, liver resection, liver surgery, shock, and heart failure and more likely to have graft dysfunction after liver transplantation. Hence, people with fatty livers are increasingly vulnerable to acute liver injury. It has been suggested reducing fat plays a central role in reversing this susceptibility. Thus, there is a need to identify improved therapies and methods of treating or preventing fatty liver disease.

Incretins, such as Glucagon like peptide- 1 (GLP-1) are gastrointestinal hormones that cause an increase in the amount of insulin released from the beta cells. Exendin-4 is the GLP-1 hormone found in the saliva of the Gila monster. Several long-lasting GLP-1 analogs having insulinotropic activity have been developed. Exenatide (Byetta) has been approved for use in treating type II diabetes. GLP-1 is inactivated by the enzyme dipeptidyl peptidase- 4 (DPP-4). Exenatide is DPP-4 resistant and has many of the actions of GLP-1.

Exendin-4 significantly reduced hepatic steatosis in obese mice. Ding et al.,

Hepatology., 2006, 43(1): 173-81. It was uncertain whether these effects were the result of direct action on hepatocytes or related to non-hepatic effectors. SUMMARY

It has been discovered that GLP-1 and analogs have a cognate receptor on human hepatocytes and that exendin-4, a GLP-1 receptor agonist, has a direct effect on the reduction of hepatic steatosis in the absence of insulin. Both glucagon-like peptide 1 receptor (GLP/R) messenger RNA and protein were detected on primary human hepatocytes, and GLP-1 receptor was internalized in the presence of GLP-1. Exendin-4, a GLP-1 agonist, increased the phosphorylation of 3-phosphoinositide-dependent kinase-1 (PDK-1), AKT, and protein kinase C zeta (PKC-zeta) in HepG2 and Huh7 cells. Treatment with exendin-4 quantitatively reduced triglyceride stores compared with control-treated cells. Exendin-4 has the beneficial effects in vitro of directly reducing hepatocyte steatosis. See Gupta et al, Hepatology., 2010, 51(5): 1584-1592. Exendin-4 mitigates ischemic liver damage and decreases fat stores from the liver when administered to obese mice with ischemia reperfusion injury of the liver.

In certain embodiments, the disclosure relates to the treatment and management of liver transplant steatosis to decrease the incidence of primary non-function and early graft dysfunction.

In certain embodiments, the disclosure relates to the use of GLP-1 pathway agonists for preventing or treating liver disease or ischemia, either in combination with dietary manipulation or other pharmacotherapy such as DPP-4 inhibitors. In certain embodiments the treatment entails a GLP-1 agonists such as GLP-1 or analogs, exendin-4, exenatide, liraglutide, taspoglutide, albiglutide, lixisenatide or salts, prodrugs, or esters thereof optionally in combination with a DPP-4 inhibitor such as alogliptin, linagliptin, saxagliptin, sitagliptin, and vildagliptin or salts, prodrugs, or esters thereof.

In certain embodiments, the disclosure relates to preservative (cells, tissues or organs such as liver) solutions comprising a GLP-1 pathway agonist and/or DPP-4 inhibitor and optionally an anticoagulant. In certain embodiments, the solutions comprise a GLP-1 pathway agonist and/or DPP-4 inhibitor in combination with a component selected from lactobionate, raffinose, hydroxyethyl starch, mannitol, histidine, and adenosine in a pH buffer (e.g., phosphate buffer).

Typically the liver preservation contains the GLP-1 pathway agonist and/or DPP-4 inhibitor in combination with a phosphate salt, sulfate salt, an amino acid, N-acetylcysteine, glutathione, histidine, tryptophan, ketoglutarate, a saccharide, glucose, a polysaccharide, lactobionate, allopurinol, trehalose, raffinose, hydroxyethyl starch, hydroxymethyl starch, dextran, vitamin, iloprost, nitroglycerin, procaine, insulin, heparin, phenoxybenzamine, penicillin, dexamethasone, trimethyl amine oxide, adenosine, dibutyryl cAMP, or adenosine triphosphate and combinations thereof. Typically, the solution is buffered to a pH of about 6.5 to 8.0 or about 7.0 to 7.8 or to about 7.0 to 7.5. In certain embodiments, the osmolality of the preservation solution is between about 270 and 330 mOsm/liter. In certain embodiments, the solution has a solution osmolality of about 200-400 mOsm/liter and a lactobionate salt.

With regard to any of the embodiments herein, the GLR-1 pathway agonist is a GLR- 1 receptor agonist selected from GLP-1, exendin-4, exenatide, liraglutide, lixisenatide, taspoglutide, and albiglutide or salts, prodrugs, or esters thereof.

With regard to any of the embodiments herein, the GLR-1 pathway agonist is an A T or mTOR agonist selected from EGF, PDGF, IGF, and insulin or salts, prodrugs, or esters thereof.

With regard to any of the embodiments herein, the DPP-4 inhibitor is alogliptin, linagliptin, saxagliptin, sitagliptin, and vildagliptin or salts, prodrugs, or esters thereof.

In certain embodiments, the disclosure relates to methods of mitigating metabolic disorders such as liver damage comprising storing a liver in a solution of any of the embodiments disclosed herein.

In certain embodiments, the disclosure relates to methods of mitigating metabolic disorders such as liver damage comprising administering a GLR-1 pathway agonist and/or a DPP-4 inhibitor to a subject diagnosed with a fatty liver under conditions such that the agonist contacts the liver such as by direct injection into the liver tissue or by injection for systemic circulation.

In certain embodiments, the disclosure relates to methods of mitigating liver damage comprising administering an effective amount of a GLR-1 pathway agonist and/or a DPP-4 inhibitor to a subject related to donating or receiving a liver transplant. In certain

embodiments, the subject is to imminently donate a liver. In certain embodiments, the subject is to imminently receive a liver transplant. In certain embodiments, the subject has been pronounced brain dead or unconscious, i.e., a living donor or a cadaver donor.

Within any of the embodiments disclosed herein, the subject is a human subject.

In certain embodiments, the GLP-1 receptor agonist prevents ischemic liver damage and makes the liver suitable for harvesting and transplantation into a recipient.

In certain embodiments, the donor liver is stored in a preservative solution disclosed herein which prevents ischemic liver damage and makes the liver more suitable for transplantation.

In certain embodiments, the subject is a living donor with a fatty or non-fatty liver. Treatment with GLP-1 prevents liver damage when the donor's liver undergoes resection (removing a piece of the liver for transplanting into a recipient). In certain embodiments, the GLP-1 receptor agonist or DPP-4 inhibitor is administered to subjects with a fatty or non-fatty liver to prevent or reduce ischemic injury to the liver resulting from surgery on the liver (such as resection due to removal of a tumor), trauma to the liver, injury to the liver from heart failure or injury to the liver from shock.

In certain embodiments, the disclosure relates to a dosing regimen of a GLP-1 receptor agonist administered to a subject on a short term-basis, e.g., at least daily or twice daily for less than 2 days, 3 days, 4 days, 5 days, 6 days, 1 week, 2 weeks, 3 weeks, or 1 month, which results in the prevention or reduction or ischemic liver damage.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows data suggesting the presence of GLP-1 R on human hepatocytes. Figure 2 shows data suggesting the reductions of steatosis on exposure to exendin-4 (exenatide).

Figure 3 shows data suggesting BAD is phosphorylated in HuH7 cells treated with free fatty acids which is pro-apoptotic and then down regulated upon treatment with GLP-1 agonist Exendin-4 (anti-apoptotic).

Figure 4 shows data suggesting ALT levels in obese mice undergoing IR injury were elevated above baseline and reduced in obese mice undergoing IR injury which were pretreated with Exendin-4.

Figure 5 shows data from a quantitative triglyceride assay suggesting there is a decrease in total triglyceride content in the Exendin-4 treated obese mice undergoing IR.

DETAILED DISCUSSION

Pretreatment of a steatotic liver with GLP-1 R agonists results in improved outcomes of liver injury in terms of a rapid reduction in liver triglyceride, decrease in apoptosis and improve in cell survival along with regulation of CD8 memory T cells which play a role in transplantation. Data suggests that exendin-4 decreases triglyceride stores in steatotic human hepatoma cells (HuH7) in vitro and in steatotic livers of ob/ob mice in vivo. Data suggests that GLP-1R acts through the cAMP and AKT pathways leading to phosphorylation of mTOR which regulates memory CD8 T cell differentiation.

GLP-1 receptor is a receptor present in various organ systems such as the pancreas, heart, brain and kidney. However its presence in the liver has been contentious since others reported that GLP-IR knock-out mice did not show hepatic metabolic changes. See Ayala et al, Diabetes., 2008, 57(2):288-297; Hansotia et al, J Clin Invest., 2007, 117(1): 143-152; Hansotia & Drucker, Regul Pept., 2005,128(2): 125-134; Hansotia et al, Diabetes., 2004, 53(5): 1326-1335; and Flock et al, Diabetes., 2007, 56(12):3006-3013.

GLP-1 and DPP-4

Glucagon- like peptide- 1 (GLP-1) is derived from the transcription of the proglucagon gene. The major source of GLP-1 in the body is the intestinal L cell that secretes GLP-1 as a gut hormone. The biologically active forms of GLP-1 are: GLP-l-(7-37) and GLP-l-(7- 36)NH2. Those peptides result from cleavage of the proglucagon molecule. Once in the circulation, GLP-1 is degraded by the enzyme dipeptidyl peptidase-4 (DPP-4). GLP-lis a potent anti -hyperglycemic hormone, inducing glucose-dependent stimulation of insulin secretion while suppressing glucagon secretion. Such glucose-dependent action is particularly attractive because GLP-1 no longer stimulates insulin to cause hypoglycemia when the plasma glucose concentration is in the normal fasting range. GLP-1 appears to restore the glucose sensitivity of pancreatic β-cells. Glucagon-like peptide- 1 analogs/agonists are a new class of drug for treatment of type 2 diabetes. GLP-1 agonists include exenatide, liraglutide, taspoglutide, albiglutide, lixisenatide or salts, prodrugs, or esters thereof. DPP-4 inhibitors include alogliptin, linagliptin, saxagliptin, sitagliptin, and vildagliptin or salts, prodrugs, or esters thereof. These GLP-1 agonists and DPP-4 inhibitors are contemplated for any of the uses described herein.

Liver transplants

Hepatic transplantation is the surgical replacement of a diseased liver with a healthy liver. Blood in the donors liver is typically replaced by an ice-cold organ storage solution until the graft liver is implanted. Implantation typically involves anastomoses (connections) of the inferior vena cava, portal vein, and hepatic artery. After blood flow is restored to the new liver, the biliary (bile duct) anastomosis is typically constructed, either to the bile duct of the recipient or to the small intestine.

Living donor liver transplantation (LDLT) is a surgical option for patients with end stage liver disease, such as cirrhosis and/or hepatocellular carcinoma often attributable to one or more of the following: long-term alcohol abuse, long-term untreated hepatitis C infection, long-term untreated hepatitis B infection. In LDLT, a piece of healthy liver is typically surgically removed from a living person and transplanted into a recipient, immediately after the diseased liver has been entirely removed. In a typical adult recipient LDLT, 55 to 70% of the liver (the right lobe) is removed from a healthy living donor. The liver of the donor will typically regenerate approaching 100% function within 4-6 weeks, and will almost reach full volumetric size with recapitulation of the normal structure soon thereafter. The transplanted portion will reach full function and the appropriate size in the recipient as well, although it will take longer than for the donor.

Like most other allografts, a liver transplant will be rejected by the recipient unless immunosuppressive drugs are used. In certain embodiments, the disclosure contemplates a therapy for treating a post-transplant recipient by administering a GLP-1 agonist and/or a DPP-4 inhibitor in combination with an immunosuppressive agent. Most liver transplant recipients receive corticosteroids plus a calcineurin inhibitor such as tacrolimus or ciclosporin plus a purine antagonist such as mycophenolate and optionally a steroid such as prednisone. If the patient has a co-morbidity such as active hepatitis B, high doses of hepatitis B immunoglobulins are administrated in liver transplant patients. In certain embodiments the disclosure contemplates administering a GLP-1 agonist and/or a DPP-4 inhibitor in combination with hepatitis immunoglobulins.

Organ preservation solutions

Within certain embodiments, the disclosure relates to composition comprising GLP-1 pathway agonists and DPP-4 inhibitors in preservation solution of organs such as the liver, heart, pancreas, or kidney. The composition for organ preservation according to the present disclosure may further comprise optional components in addition to the GLP-1 pathway agonists and DPP-4 inhibitors. Examples of such optional components include sugars, electrolytes, organic acids, vitamins, amino acids, hormones, antibiotics, active oxygen scavengers, anticoagulants, antihypertensive agents, cryoprotective compounds, fibrinolytic agents, additives (carriers) for pharmaceutical preparations, and solvents. Sugars include, for example, glucose, sucrose, lactose, raffinose, trehalose, stachyose, galactosyltrehalose, mannitol, sorbitol, maltitol, erythritol, palatinose, lactitol, xylitol, hydroxyethyl starch, and dextran. Electrolytes include, for example, sodium chloride, potassium chloride, magnesium chloride, calcium chloride, sodium dihydrogenphosphate, potassium dihydrogenphosphate, disodium hydrogenphosphate, dipotassium hydrogenphosphate, sodium carbonate, and potassium carbonate. Organic acids include, for example, gluconic acid, lactic acid, acetic acid, propionic acid, beta-hydroxybutyrate, citric acid, fumaric acid, succinic acid, oxalic acid, and maleic acid. Hormones include, for example, dexamesone and hydrocortisone, and antibiotics include, for example, penicillin G and streptomycin. Anticoagulants include, for example, heparin or analogs, antihypertensive agents include, for example, vasodilators and chlorpromazine, and thrombolytic agents include, for example, urokinase. Additives for pharmaceutical preparations include, for example, vehicles, dispersants, preservatives, antiseptics, emulsifiers, extenders, colorants, surfactants, buffers, solubilizers, stabilizers, and pH adjusters. Solvents include, for example, purified water, sterilized pure water, and physiological saline.

In the present disclosure, when the composition for organ preservation has been dissolved in a predetermined solvent, or when the composition for organ preservation is in a solvent form, preferably, the solution containing the composition for organ preservation dissolved therein contains, in addition to the GLP-1 pathway agonists and DPP-4 inhibitors, predetermined alkali metal ions, alkaline earth metal ions, and anions in a predetermined concentration. Therefore, when the above-described electrolyte, organic acid, or salt of the organic acid (for example, sodium salt or potassium salt) is incorporated in the composition for organ preservation according to the present disclosure, upon the dissolution of the composition for organ preservation, desired ions can be produced.

Histidine-tryptophan-ketoglutarate, or Custodiol HTK solution is a contemplated organ preservation solution. HTK solution is based on the principle of inactivating organ function by intensive buffering of the extracellular space by means of histidine so as to prolong the period during which the organs will tolerate interruption of oxygenated blood. In certain embodiments of the disclosure, the solution for preservation of organs contains GLP-1 pathway agonists and/or DPP-4 inhibitors in combination with histidine such as a solution containing sodium, potassium, magnesium, calcium, ketoglutarate/glutamic acid, histidine, mannitol, and tryptophan with an osmolarity of about 310 mOsm/L.

U.S. Patent Number 4,879,283, hereby incorporated by reference in its entirety, discloses contemplated organ preservation solutions. In certain embodiments, the disclosure contemplates a solution for preservation of organs comprising lactobionate and raffinose as an impermeation agent, hydroxyethyl starch as a colloid osmo-regulator, and adenosine and/or insulin as an energy metabolism promoting component in combination with GLP-1 pathway agonists and/or DPP-4 inhibitors. In certain embodiments, the anion lactobionate and raffinose, has K⁺ of 120 mM and Na⁺ of 30 mM. The solution may comprise a modified hydroxyethyl starch having a weight average molecular weight of from about 150,000 to about 350,000 daltons and degree of substitution of from about 0.4 to about 0.7 or a hydroxyethyl starch having a weight average molecular weight of from about 200,000 to about 300,000 daltons or substantially free of hydroxyethyl starch having a molecular weight of less than about 50,000 daltons or the hydroxyethyl starch is dialyzed against distilled- deionized water or otherwise treated to remove several contaminants. The materials removed by the dialysis process are the very smallest hydroxyethyl starch components, including the ethylene glycol and ethylene chlorohydrin side products of the hydroxyethylation as well as the residual acetone and sodium chloride.

U.S. Patent Number 5,145,771, hereby incorporated by reference in its entirety, discloses contemplated organ preservation solutions. In certain embodiments, the disclosure contemplates an organ preservation solution comprising a GLP-1 pathway agonist and/or a DPP-4 inhibitor in combination with adenosine, sodium, potassium, calcium and magnesium ions in a physiologically acceptable amount, and water for injection sufficient to make a liter of solution. Typically the solutions have a pH of about 6.0 to 7.5.

U.S. Patent Number 5,200,398, hereby incorporated by reference in its entirety, discloses contemplated organ preservation solutions. In certain embodiments, the disclosure contemplates an organ preservation solution comprising a GLP-1 pathway agonist and/or a DPP-4 inhibitor in combination with glucuronic acid or a physiologically tolerated salt or ester thereof.

U.S. Patent Number 5,306,711, hereby incorporated by reference in its entirety, discloses contemplated organ preservation solutions. In certain embodiments, the disclosure contemplates an organ preservation solution comprising a GLP-1 pathway agonist and/or a DPP-4 inhibitor in combination with dextran (e.g., 20-30 wt %) having an average molecular weight of 10,000 daltons or less, said preservative solution having a pH of 7.0 or greater.

U.S. Patent Number 5,704,297, hereby incorporated by reference in its entirety, discloses contemplated organ preservation solutions. In certain embodiments, the disclosure contemplates an organ preservation solution comprising a GLP-1 pathway agonist and/or a DPP-4 inhibitor in combination with hydroxyethyl starch e.g., a hydroxyethyl starch comprising from about 4% to about 40% by weight of the composition optionally in addition a component chosen from dextrose, lactose or mannitol.

U.S. Patent Number 6,060,232, hereby incorporated by reference in its entirety, discloses contemplated organ preservation solutions. In certain embodiments, the disclosure contemplates an organ preservation solution comprising a GLP-1 pathway agonist and/or a DPP-4 inhibitor in combination with about Na⁺ (2-30 mM), K⁺ (70-130 mM), Mg²⁺(30-40 mM), Ce⁺ (2-20 mM), S0₄ ^2~ (80-95 mM) and raffmose (20-60 mM) and about 10% polyethylene glycol in phosphate buffer at a pH of about 7.4 having a total osmolality of approximately 290 mOsm.

U.S. Patent Number 6,365,338, hereby incorporated by reference in its entirety, discloses contemplated organ preservation solutions. In certain embodiments, the disclosure contemplates an organ preservation solution comprising a GLP-1 pathway agonist and/or a DPP-4 inhibitor in combination with trehalose, magnesium sulfate, calcium chloride, heparin, dextran, nitroglycerin, adenosine, L-arginine, allopurinol, reduced glutathione, an energy source (e.g., cyclic AMP, cyclic GMP or adenosine) and potassium phosphate.

U.S. Patent Number 7,977,042, hereby incorporated by reference in its entirety, discloses contemplated organ preservation solutions. In certain embodiments, the disclosure contemplates an organ preservation solution comprising a GLP-1 pathway agonist and/or a DPP-4 inhibitor in combination with potassium phosphate, glutathione, adenosine, lactobionate, sodium, potassium, allopurinol and a membrane stabilizer selected from the group consisting of calcium, glycine, chlorpromazine, and combinations thereof.

U.S. Patent Number 8,017,312, hereby incorporated by reference in its entirety, discloses contemplated organ preservation solutions. In certain embodiments, the disclosure contemplates an organ preservation solution comprising a GLP-1 pathway agonist and/or a DPP-4 inhibitor in combination with one cyclodextrin optionally combined with an antioxidant.

EXPERIMENTAL

Example 1: GLP-IR on human hepatocytes

See See Gupta et al, Hepatology., 2010, 51(5): 1584-1592, hereby incorporated by reference in its entirety. Primary human hepatocytes and Huh7 cells show the presence of GLP-IR on western blot analysis. Brain lysate was used as a positive control (Fig. 1A).

Bioluminescence analysis for GPCRs revealed the presence of GLP-IR on Huh7 cells. Bars represent the percent increase in bioluminescence in GLP-IR compared with no primary antibody treatment (Fig. IB). Example 2: Exendin-4 decreases steatosis in an in vitro model with human hepatoma cell line

An in vitro model of steatosis with human hepatoma cell line (HuH7) was developed by the addition of free fatty acids (FFA). Data suggests that GLP-1R agonists had a direct and rapid action in decreasing hepatic steatosis (Fig. 2). Triglyceride (TG) assay was performed on Huh7 cell lysate after treatment with palmitic and oleic acid followed by exposure to exendin-4. Bars represent the percent increase in TG content and the percent decrease on treatment with exendin-4. Data are presented as the mean 6 SE. **P < 0.05 versus untreated steatotic cells. The experiment was repeated three times in triplicate and compared with free fatty acids exposed and untreated controls.

Example 3: BAD is phosphorylated in steatotic Huh7 cells

Bad is phosphorylated in steatotic Huh7 cells and then down regulated upon treatment with GLP-1R agonist exendin-4 (Fig. 3). This implies that apoptotic pathways are down regulated on treatment with exendin-4.

Example 4: Serum ALT levels in obese mice were reduced when pretreated with Exendin-4 when exposed to IR injury

Peritoneum is entered through a midline incision after prepping the abdomen. After exposing the porta hepatis, a small pediatric vessel clamp is applied to the portal vein and hepatic artery and ischemia are induced for 20m. The vessel clamp is removed and the portal and hepatic blood flow is restored (reperfusion). Once the signs of reperfusion are evident (by change in the color of the liver) both the layers of the abdomen are closed and the animal are placed in a recovery cage and allowed free access to food and water. Surviving animals are monitored closely and then sacrificed at 12 hours post operatively.

Figure 4 shows the difference in size of ob/ob mice and its lean littermate (a), a clamp placed over the portal vein, hepatic artery and bile duct in situ (b) and hepatic ischemia (c). This data suggests that on sacrificing the mice at 12 h post surgery there was a significant decrease in the serum ALT in ob/ob mice pretreated with Ex-4 as compared to saline treated mice undergoing I-R injury. There was a decrease in triglyceride content in the livers of pretreated mice as compared to mice treated with saline undergoing IR injury (Figure 5).

Claims

CLAIMS What We Claim:

1. A preservative solution comprising a GLR-1 pathway agonist and/or DPP-4 inhibitor.

2. The preservative solution of Claim 1 further comprising a component selected from lactobionate, raffinose, hydroxyethyl starch, mannitol, histidine, and adenosine in a pH buffer.

3. The preservative solution of Claim 1, wherein the solution is buffered to a pH of about 6.5 to 8.0.

4. The preservative solution of Claims 1-3, wherein the GLR-1 pathway agonist is a GLR-1 receptor agonist selected from exendin-4, exenatide, liraglutide, lixisenatide, taspoglutide, and albiglutide or salts, prodrugs, or esters thereof.

5. The preservative solution of Claims 1-3, wherein the GLR-1 pathway agonist is an AKT or mTOR agonist selected from EGF, PDGF, IGF, and insulin or salts, prodrugs, or esters thereof.

6. The liver preservation solution of Claim 1-3, wherein the DPP-4 inhibitor is selected from alogliptin, linagliptin, saxagliptin, sitagliptin, and vildagliptin or salts, prodrugs, or esters thereof.

7. A method of mitigating liver damage comprising storing a liver in a solution of Claims 1-6.

8. A method of mitigating liver damage comprising administering a GLR-1 pathway agonist and/or a DPP-4 inhibitor to a subject diagnosed with a fatty liver under conditions such that the agonist contacts the liver.

9. A method of mitigating liver damage comprising administering an effective amount of a GLR-1 pathway agonist and/or a DPP-4 inhibitor to a subject related to donating or receiving a liver transplant.

10. The method of Claim 9, wherein the subject is to imminently donate a liver.

11. The method of Claim 9, wherein the subject is to imminently receive a liver transplant.

12. The method of Claim 9, wherein the subject is brain dead or unconscious.

13. The method of Claim 9, wherein the subject is a living donor or a cadaver.

14. The method of Claims 7-13, wherein the GLR-1 pathway agonist is a GLR-1 receptor agonist selected from exendin-4, exenatide, liraglutide, lixisenatide, taspoglutide, and albiglutide or salts, prodrugs, or esters thereof.

15. The method of Claims 7-13, wherein the GLR-1 pathway agonist is an AKT or mTOR agonist selected from EGF, PDGF, IGF, and insulin or salts, prodrugs, or esters thereof.

16. The method of Claims 7-13, wherein the DPP-4 inhibitor is selected from alogliptin, linagliptin, saxagliptin, sitagliptin, and vildagliptin or salts, prodrugs, or esters thereof.

17. The method of Claims 7-16, wherein the subject is a human subject.