Free Fatty Acid Receptors (FFARs): Emerging Therapeutic Targets for the Management of Diabetes Mellitus.

Free fatty acids (FFAs) present in our dietary fats not only act as vital nutrients but also function as signalling molecules and modulate key biological functions through their active involvement in a multitude of energy metabolism pathways. However, it has been reported that excessive intake of dietary fat contributes to the development of different types of Diabetes mellitus. Free fatty acid receptors are the key regulators of most metabolic disorders. Among them, diabetes mellitus is a severe growing disorder and found in every corner of the world. For various metabolic disorders, particularly type 2 diabetes mellitus, these different free fatty acid receptors are being explored as drug targets. In the present review, various FFAs sensing G-protein coupled receptors (GPR) like GPR40 (FFAR1), GPR43 (FFAR2), GPR41 (FFAR3), GPR120 (FFAR4), and GPR84 are being explored as emerging novel therapeutic targets for antidiabetic drugs. Additionally, this review has covered pre-clinical discovery and development of different selective ligands targeted to these receptors starting from hit identification to lead optimization via chemical modification and the challenges and tactics selected by different medicinal chemists to improve potency, physicochemical properties, safety profiles, and pharmacokinetics of different FFAR agonists for making a potential drug candidate. Several molecules have been withdrawn in the clinical trials without reporting any reasons. We believe that this review will help the researchers to find a new direction in the discovery of new antidiabetic drugs.

Withaferin A Inhibits Fatty Acid Synthesis in Rat Mammary Tumors.

Withaferin A (WA), which is a small molecule derived from a medicinal plant (Withania somnifera), inhibits growth of human breast cancer xenografts and mammary tumor development in rodent models without any toxicity. However, the mechanism underlying inhibition of mammary cancer development by WA administration is not fully understood. Herein, we demonstrate that the fatty acid synthesis pathway is a novel target of WA in mammary tumors. Treatment of MCF-7 and MDA-MB-231 cells with WA resulted in suppression of fatty acid metabolizing enzymes, including ATP-citrate lyase (ACLY), acetyl-CoA carboxylase 1 (ACC1), fatty acid synthase (FASN), and carnitine palmitoyltransferase 1A (CPT1A). Expression of FASN and CPT1A was significantly higher in N-methyl-N-nitrosourea-induced mammary tumors in rats when compared with normal mammary tissues. WA-mediated inhibition of mammary tumor development in rats was associated with a statistically significant decrease in expression of ACC1 and FASN and suppression of plasma and/or mammary tumor levels of total free fatty acids and phospholipids. WA administration also resulted in a significant increase in percentage of natural killer cells in the spleen. The protein level of sterol regulatory element binding protein 1 (SREBP1) was decreased in MDA-MB-231 cells after WA treatment. Overexpression of SREBP1 in MDA-MB-231 cells conferred partial but significant protection against WA-mediated downregulation of ACLY and ACC1. In conclusion, circulating and/or mammary tumor levels of fatty acid synthesis enzymes and total free fatty acids may serve as biomarkers of WA efficacy in future clinical trials. PREVENTION RELEVANCE: The present study shows that breast cancer prevention by WA in rats is associated with suppression of fatty acid synthesis.

Magnesium Supplementation Stimulates Autophagy to Reduce Lipid Accumulation in Hepatocytes via the AMPK/mTOR Pathway.

Metabolic-associated fatty liver disease (MAFLD) (previously known as nonalcoholic fatty liver disease (NAFLD)) is a disease with high worldwide prevalence, but with limited available therapeutic interventions. Autophagy is a cell survival mechanism for clearing excess lipids in hepatocytes and affects the occurrence and development of MAFLD. In addition, some studies have shown that magnesium deficiency is common in patients with obesity and metabolic syndrome. Magnesium supplementation can effectively improve metabolism-related diseases such as obesity and fatty liver. Our study successfully constructed a cellular model of MAFLD by 1 mM free fatty acid (FFA) intervention in LO2 cells for 24 h, and there was an increase in lipid accumulation in hepatocytes after FFA intervention. Magnesium supplementation was shown to reduce lipid deposition in hepatocytes induced by FFA, and Western blotting (WB) analysis showed that magnesium supplementation could downregulate the expression of Fasn and SREBP1 and increase the expression of LPL, suggesting that magnesium can reduce lipid accumulation by reducing lipid synthesis and increasing lipid oxidation. Magnesium supplementation could affect cellular lipid metabolism by activating the AMPK/mTOR pathway to stimulate autophagy. Our results identified a relationship between magnesium and lipid accumulation in hepatocytes and showed that magnesium supplementation reduced lipid deposition in hepatocytes by activating autophagy by activating the AMPK-mTOR pathway.

Xanthine oxidase inhibitor urate-lowering therapy titration to target decreases serum free fatty acids in gout and suppresses lipolysis by adipocytes.

OBJECTIVE: Linked metabolic and cardiovascular comorbidities are prevalent in hyperuricemia and gout. For mechanistic insight into impact on inflammatory processes and cardiometabolic risk factors of xanthine oxidase inhibitor urate-lowering therapy (ULT) titration to target, we performed a prospective study of gout serum metabolomes from a ULT trial. METHODS: Sera of gout patients meeting the 2015 ACR/EULAR gout classification criteria (n = 20) and with hyperuricemia were studied at time zero and weeks 12 and 24 of febuxostat or allopurinol dose titration ULT. Ultrahigh performance liquid chromatography-tandem mass spectroscopy acquired the serum spectra. Data were assessed using the Metabolon and Metaboloanalyst software. Lipolysis validation assays were done in febuxostat and/or colchicine-treated 3T3-L1 differentiated adipocytes. RESULTS: Serum urate decreased from time zero (8.21 ±1.139 SD) at weeks 12 (5.965 ± 1.734 SD) and 24 (5.655 ±1.763 SD). Top metabolites generated by changes in nucleotide and certain amino acid metabolism and polyamine pathways were enriched at 12 and 24 weeks ULT, respectively. Decreases in multiple fatty acid metabolites were observed at 24 weeks, linked with obesity. In cultured adipocytes, febuxostat significantly decreased while colchicine increased the lipolytic response to ß-adrenergic-agonism or TNF. CONCLUSION: Metabolomic profiles linked xanthine oxidase inhibitor-based ULT titration to target with reduced serum free fatty acids. In vitro validation studies revealed that febuxostat, but not colchicine, reduced lipolysis in cultured adipocytes. Since soluble urate, xanthine oxidase inhibitor treatment, and free fatty acids modulate inflammation, our findings suggest that by suppressing lipolysis, ULT could regulate inflammation in gout and comorbid metabolic and cardiovascular disease.

Effects of Orlistat or Telmisartan on the Serum Free Fatty Acids in Non-alcoholic Fatty Liver Disease Patients: An Open-Labeled Randomized Controlled Study.

BACKGROUND: One of the important inducers of inflammatory responses and accumulation of fat in hepatocytes is free fatty acids which ultimately lead to the development of non-alcoholic fatty liver disease. Patients with non-alcoholic fatty liver disease have high levels of plasma free fatty acids which are usually associated with type 2 diabetes and components of metabolic syndrome including dyslipidemia. Objective of this research is to investigate the effects of orlistat (a lipase enzyme inhibitor) or telmisartan (an angiotensin receptor blocker) on the serum free fatty acids in non-alcoholic fatty liver disease patients taking into consideration the baseline lipid profile. METHODS: This open-label clinical trial was carried out in the Department of Pharmacology, College of Medicine at the University of Sulaimani in cooperation with Shar Teaching Hospital in Sulaimani city-Kurdistan Region of Iraq. A total number of 74 non-alcoholic fatty liver disease patients were recruited and grouped randomly into group I (n = 25) treated with orlistat (120 mg/day orally) for 12 weeks, group II (n = 24) treated with telmisartan (20 mg/day orally) for 8 weeks, and group III (n = 25) treated with placebo (carboxy- methyl cellulose) once daily. Fasting serum level of free fatty acid and lipid profile including total cholesterol, triglyceride, high-density lipoprotein, and non-high-density lipoproteins were determined. RESULTS: Orlistat and telmisartan significantly reduced the triglyceride-glucose index and free fatty acid levels (P < .001) in patients with non-alcoholic fatty liver diseases. CONCLUSION: Short-term treatment with orlistat or telmisartan produce effective and significant reductions in FFAs in patients with non-alcoholic fatty liver disease compared to placebo. Orlistat effectively reduces the free fatty acid irrespective of the baseline lipid profile.

Free Fatty Acid Receptor 4 (FFA4) Activation Ameliorates Imiquimod-Induced Psoriasis in Mice.

Dietary supplementation with n-3 polyunsaturated fatty acids (n-3 PUFA) has been used as an adjunct therapy for psoriasis due to its anti-inflammatory properties. Free fatty acid receptor 4 (FFA4 or GPR120) is a receptor-sensing n-3 PUFA. In the present study, we examined whether FFA4 acted as a therapeutic target for n-3 PUFA in psoriasis therapy. Experimentally, psoriasis-like skin lesions were induced by treatment with imiquimod for 6 consecutive days. A selective FFA4 agonist, Compound A (30 mg/kg), was used in FFA4 WT and FFA4 KO mice. Imiquimod-induced psoriasis-like skin lesions, which present as erythematous papules and plaques with silver scaling, as well as markedly elevated IL-17/IL-23 cytokine levels in skin tissues, were significantly suppressed by Compound A in FFA4 WT mice, but not in FFA4 KO mice. Enlarged lymph nodes and spleens, as well as imiquimod-induced, elevated IL-17/IL-23 cytokine levels, were also strongly suppressed by Compound A in FFA4 WT mice, but not in FFA4 KO mice. Imiquimod-induced increases in the CD4+IL-17A+ T cell population in lymph nodes and spleens were suppressed by Compound A treatment in FFA4 WT mice; however, this was not seen in FFA4 KO mice. Furthermore, compound A suppressed the differentiation of CD4+ naïve T cells from splenocytes into TH17 cells in an FFA4-dependent manner. In conclusion, we demonstrated that the activation of FFA4 ameliorates imiquimod-induced psoriasis, and the suppression of the differentiation of TH17 cells may partly contribute to its efficacy. Therefore, we suggest that FFA4 could be a therapeutic target for psoriasis therapy.

Activation of Free Fatty Acid Receptor 4 (FFA4) Ameliorates Ovalbumin-Induced Allergic Asthma by Suppressing Activation of Dendritic and Mast Cells in Mice.

Epidemiological and clinical studies have suggested that intake of n-3 polyunsaturated fatty acids (PUFA) reduces the incidence of allergic airway diseases and improves pulmonary function in patients with allergic asthma. However, the pharmacological targets of PUFA have not been elucidated upon. We investigated whether free fatty acid receptor 4 (FFA4, also known as GPR120) is a molecular target for beneficial PUFA in asthma therapy. In an ovalbumin (OVA)-induced allergic asthma model, compound A (a selective agonist of FFA4) was administrated before OVA sensitization or OVA challenge in FFA4 wild-type (WT) and knock-out (KO) mice. Compound A treatment of RBL-2H3 cells suppressed mast cell degranulation in vitro in a concentration-dependent manner. Administration of compound A suppressed in vivo allergic characteristics in bronchoalveolar lavage fluid (BALF) and lungs, such as inflammatory cytokine levels and eosinophil accumulation in BALF, inflammation and mucin secretion in the lungs. Compound A-induced suppression was not only observed in mice treated with compound A before OVA challenge, but in mice treated before OVA sensitization as well, implying that compound A acts on mast cells as well as dendritic cells. Furthermore, this suppression by compound A was only observed in FFA4-WT mice and was absent in FFA4-KO mice, implying that compound A action is mediated through FFA4. Activation of FFA4 may be a therapeutic target of PUFA in allergic asthma by suppressing the activation of dendritic cells and mast cells, suggesting that highly potent specific agonists of FFA4 could be a novel therapy for allergic asthma.

Chemoprevention in familial adenomatous polyposis: past, present and future.

Familial adenomatous polyposis (FAP) is a hereditary colorectal cancer syndrome characterized by colorectal adenomas and a near 100% lifetime risk of colorectal cancer (CRC). Prophylactic colectomy, usually by age 40, is the gold-standard therapy to mitigate this risk. However, colectomy is associated with morbidity and fails to prevent extra-colonic disease manifestations, including gastric polyposis, duodenal polyposis and cancer, thyroid cancer, and desmoid disease. Substantial research has investigated chemoprevention medications in an aim to prevent disease progression, postponing the need for colectomy and temporizing the development of extracolonic disease. An ideal chemoprevention agent should have a biologically plausible mechanism of action, be safe and easily tolerated over a prolonged treatment period, and produce a durable and clinically meaningful effect. To date, no chemoprevention agent tested has fulfilled these criteria. New agents targeting novel pathways in FAP are needed. Substantial preclinical literature exists linking the molecular target of rapamycin (mTOR) pathway to FAP. A single case report of rapamycin, an mTOR inhibitor, used as chemoprevention in FAP patients exists, but no formal clinical studies have been conducted. Here, we review the prior literature on chemoprevention in FAP, discuss the rationale for rapamycin in FAP, and outline a proposed clinical trial testing rapamycin as a chemoprevention agent in patients with FAP.

Antibacterial Free Fatty Acids and Monoglycerides: Biological Activities, Experimental Testing, and Therapeutic Applications.

Antimicrobial lipids such as fatty acids and monoglycerides are promising antibacterial agents that destabilize bacterial cell membranes, causing a wide range of direct and indirect inhibitory effects. The goal of this review is to introduce the latest experimental approaches for characterizing how antimicrobial lipids destabilize phospholipid membranes within the broader scope of introducing current knowledge about the biological activities of antimicrobial lipids, testing strategies, and applications for treating bacterial infections. To this end, a general background on antimicrobial lipids, including structural classification, is provided along with a detailed description of their targeting spectrum and currently understood antibacterial mechanisms. Building on this knowledge, different experimental approaches to characterize antimicrobial lipids are presented, including cell-based biological and model membrane-based biophysical measurement techniques. Particular emphasis is placed on drawing out how biological and biophysical approaches complement one another and can yield mechanistic insights into how the physicochemical properties of antimicrobial lipids influence molecular self-assembly and concentration-dependent interactions with model phospholipid and bacterial cell membranes. Examples of possible therapeutic applications are briefly introduced to highlight the potential significance of antimicrobial lipids for human health and medicine, and to motivate the importance of employing orthogonal measurement strategies to characterize the activity profile of antimicrobial lipids.

Free fatty acid suppositories are as effective as docusate sodium and sorbitol enemas in treating constipation in children.

AIM: A well-documented, clinically proven per rectum treatment for childhood constipation is needed. This phase two clinical trial evaluated the efficacy of suppositories containing free fatty acids (FFA) compared with Klyx docusate sodium and sorbitol enemas. METHODS: A randomised, controlled, single-blind study was undertaken on 77 children aged between one and 17 who presented to an emergency department in Iceland and were diagnosed with constipation. In stage one, 23 patients were randomised to receive lower dose FFA suppositories or Klyx (n = 33). In stage two, 21 different patients were randomised to receive higher dose suppositories and compared with the same Klyx control subjects. RESULTS: The suppositories were effective at bowel emptying in 39% of the group who received the lower FFA doses and 81% of the group receiving higher doses, compared with 88% in the Klyx control group. Symptom relief was obtained in 30% of the group receiving the lower doses and 71% of the group receiving the higher doses, compared with 73% in the control group. CONCLUSION: The higher dose FFA suppositories were as effective as the Klyx enemas with regard to bowel emptying and symptom relief and might provide an important and less invasive alternative for childhood constipation.