Fatty Acid Analogue Research Articles

Fatty Acid Metabolism Signature Contributes to the Molecular Diagnosis of a Malignant Gastric Cancer Subtype with Poor Prognosis and Lower Mutation Burden.

Gastric cancer (GC) is a common gastrointestinal tumor with high morbidity and mortality. Fatty acid metabolism (FAM) contributes to GC development. Patents have been issued for the use of compositions comprising fatty acid analogues for the treatment of many clinical conditions. However, its clinical significance and its relationship with tumor-related mutations have not been thoroughly discovered. This study was conducted to analyze and explore FAM-related genes' molecular characteristics, prognostic significance, and association with tumor- related mutations. The gastric adenocarcinoma's transcriptome, clinical data, and tumor mutation load (TMB) data were downloaded from TCGA and GEO databases. The differentially expressed FAM genes (FAM DEGs) between cancer and control samples were screened, and their correlation with TMB and survival was analyzed. A PPI network of FAM DEGs was constructed, and a downscaling clustering analysis was performed based on the expression of the FAM DEGs. Further immuno- infiltration and GO/KEGG enrichment analyses of the identified FAM clusters were performed to explore their heterogeneity in biological functions. The effects of FAM score and gastric cancer (STAD) on TMB, MSI, survival prognosis, and drug sensitivity were jointly analyzed, and finally, a single-gene analysis of the obtained core targets was performed. Through differential analysis, 68 FAM DEGs were obtained, and they were highly associated with STAD tumor mutation load. In addition, a high FAM DEGs CNV rate was observed. The PPI network showed a complex mutual correlation between the FAM DEGs. Consensus clustering classified the patients into three clusters based on the FAM DEGs, and the clusters presented different survival rates. The GSVA and immune infiltration analysis revealed that metabolism, apoptosis, and immune infiltration-related pathways were variated. In addition, FAM genes, STAD prognostic risk genes, and PCA scores were closely associated with the survival status of STAD patients. FAM score was closely correlated with STAD TMB, MSI, and immunotherapy, and the TMB values in the low FAM score group were significantly higher than those in the high FAM score group. Finally, combining the above results, it was found that the core gene PTGS1 performed best in predicting STAD survival prognosis and TMB/MSI/immunotherapy. Fatty acid metabolism genes affect the development of gastric adenocarcinoma and can predict the survival prognosis, tumor mutational load characteristics, and drug therapy sensitivity of STAD patients, which can help explore more effective immunotherapy targets for GC.

Perfusion metabolism mismatch predicts short-term complications in Takotsubo syndrome

Abstract Background Takotsubo syndrome (TTS) is a transient cardiac condition triggered by sudden emotional or physical stress characterized by LV dysfunction in the absence of obstructive epicardial coronary artery disease. 123I-BMIPP, an iodinated fatty acid analogue, can identify impaired myocardial metabolic activity. With the use of dual SPECT protocol, reduced uptake of 123I-BMIPP compared to perfusion which is called perfusion-metabolic mismatch is observed in apical regions in TTS. The mismatch may indicate jeopardized but viable myocardium, reflecting transient ischemic damage or metabolically stunned myocardium. However, the association between the perfusion metabolism mismatch in TTS and its complications remains underexplored. Purpose Our study aimed to analyze the degree of perfusion metabolism mismatch at the acute phase in TTS and investigate its association with short-term complications. Methods This retrospective study conducted between 2012 and 2024 at a single center included 82 patients diagnosed with TTS. Patients underwent dual SPECT imaging using 99mTc or 201 Tl and 123I-BMIPP within two weeks of admission. We applied quantitative analysis using QGS/QPS software from Cedars-Sinai. Total perfusion deficit ("TPD") was calculated based on sex-matched normal limits providing the extent of perfusion abnormality. Meanwhile, perfusion-metabolism mismatch scores ("worsen") were determined by comparing the total BMIPP counts to the total counts of perfusion. We then assessed the correlation of these imaging findings with biomarkers, regional wall motion abnormalities, and the occurrence of short-term complications. Short-term complications included heart failure, left ventricular outflow (LVOT) obstruction, mitral regurgitation, cardiac arrhythmia, cardiogenic shock, left ventricle (LV) rupture, and cardiac death during the hospitalization period. Results All study patients exhibited wall motion abnormalities seen in apical segments. The count of myocardial segments with regional wall motion abnormality was correlated with both TPD (r=0.34, p=0.002) and perfusion metabolic mismatch score (r=0.40, p<0.001). TPD had a moderate correlation coefficient with max CK-MB (r=0.44, p<0.001) and troponin T (r=0.40, p<0.001) levels. However, perfusion metabolic mismatch did not display correlations with max CK-MB (r=0.05, p=0.65), and Troponin T (r=0.12, p=0.28) levels. Among 82 patients, 37 patients experienced any short-term complications. Importantly, patients with short-term complications had elevated perfusion mismatch scores compared to those without short-term complications (14.0 [6.0-22.5] vs. 5.0 [3.0-10.0], p<0.001). However, no significant difference was observed in TPD between the two groups (9.0 [4.5-20.0] vs. 7.0 [3.0-12.0], p=0.130). Conclusions Our research highlights a significant association between perfusion-metabolism mismatch and an increased risk for short-term complications in patients with Takotsubo syndrome.

Stereoselective Syntheses of Polyunsaturated Fatty Acids, 13-(S)-HODE and 15-(S)-HETE.

Polyunsaturated fatty acids and their metabolites have been reported in which their pathway has potential for the modulation of cancer cell growth. 13-(S)-HODE and 15-(S)-HETE, both of which are main metabolites of 15-LOXs, play an important role as endogenous ligands in biological systems. However, the modification of 13-(S)-HODE and 15-(S)-HETE in pharmaceutical applications has not been explored widely. Herein, we report the stereoselective syntheses of 13-(S)-HODE, 15-(S)-HETE, and its derivatives to enable the synthesis of bioactive fatty acid analogues.

SGLT2 Inhibitor Dapagliflozin Increases Skeletal Muscle and Brain Fatty Acid Uptake in Individuals With Type 2 Diabetes: A Randomized Double-Blind Placebo-Controlled Positron Emission Tomography Study.

The aim of this study was to investigate the impact of the sodium-glucose cotransporter 2 (SGLT2) inhibitor dapagliflozin on tissue fatty acid (FA) uptake in the skeletal muscle, brain, small intestine, and subcutaneous and visceral adipose tissue of individuals with type 2 diabetes by using positron emission tomography (PET). In a 6-week randomized double-blind placebo-controlled trial, 53 patients with type 2 diabetes treated with metformin received either 10 mg dapagliflozin or placebo daily. Tissue FA uptake was quantified at baseline and end of treatment with PET and the long-chain FA analog radiotracer 14(R,S)-[18F]fluoro-6-thia-heptadecanoic acid. Treatment effects were assessed using ANCOVA, and the results are reported as least square means and 95% CIs for the difference between groups. A total of 38 patients (dapagliflozin n = 21; placebo n = 17) completed the study. After 6 weeks, skeletal muscle FA uptake was increased by dapagliflozin compared with placebo (1.0 [0.07, 2.0] μmol ⋅ 100 g-1 ⋅ min-1; P = 0.032), whereas uptake was not significantly changed in the small intestine or visceral or subcutaneous adipose tissue. Dapagliflozin treatment significantly increased whole-brain FA uptake (0.10 [0.02, 0.17] μmol ⋅ 100 g-1 ⋅ min-1; P = 0.01), an effect observed in both gray and white matter regions. Six weeks of treatment with dapagliflozin increases skeletal muscle and brain FA uptake, partly driven by a rise in free FA availability. This finding is in accordance with previous indirect measurements showing enhanced FA metabolism in response to SGLT2 inhibition and extends the notion of a shift toward increased FA use to muscle and brain.

#289 Lipocalin-2 promotes cardiovascular calcification in chronic kidney disease by upregulating STAT3/NCOA4-mediated ferritinophagy and ferroptosis

Abstract Background and Aims Cardiovascular calcification (CVC) is a common complication of chronic kidney disease (CKD) and contributes to cardiovascular morbidity and mortality without any effective therapies. To date, the underlying mechanism of CKD-CVC has not been elucidated. Recent studies suggest that ferroptosis is a novel programmed cell death that may play a role in the process of CKD-CVC, but the mechanism is largely unclear. Ferritinophagy is an important inducer of ferroptosis that is regulated by nuclear receptor coactivator 4 (NCOA4). However, the relationship between ferritinophagy and CKD-CVC has not been explored. Lipocalin-2 (LCN2) is an iron-trafficking protein that has been associated with both osteogenesis and ferroptosis, but the exact role and molecular mechanism of LCN2 in CKD-CVC needs to be explored. Method A cross-sectional clinical study was utilized to examine the association between LCN2 expression and CKD-CVC in serum and calcified radial arteries of CKD patients. LCN2 knockout mice, their wild type littermates and mice infected with VSMCs-targeted adeno-associated virus encoding LCN2 gene or negative control gene were all fed by the high adenine and phosphate diet to induce CKD-CVC.VSMCs transfected with LCN2-overexpressing lentivirus, LCN2-shRNA lentivirus or LCN2 siRNA and recombinant LCN2 stimulated VSMCs were treated under the condition of calcifying medium to investigate the role of LCN2 in CKD-CVC in vitro. Cardiovascular calcification was evaluated by Von-kossa staining and tissue calcium content assay. VSMCs calcification were checked by the Alizarin Red Staining and cellular calcium content assay. Cellular reactive oxygen species (ROS) were measured by the DCFDA assay. Lipid peroxidation was measured by the fluorescence of the fatty acid analog C11-BODIPY581/591 probe. Intracellular labile ferrous iron levels were measured by fluorescence of Phen Green SK probe and ferro-orange probe. Transmission electron microscopy was also used to examine mitochondrial change of ferroptosis. Results The cross-sectional study identified that LCN2 levels in serum and radial arteries were significantly increased as the severity of CKD-CVC increased. High adenine and phosphate diet intake provokes renal fibrosis and cardiovascular calcification in vivo. In vitro, five-days high phosphate sodium stimulation induced calcium deposition and osteoblastic trans differentiation of VSMCs. Meanwhile, high phosphate also increased the levels of ferroptosis in VSMCs as evidenced by decreased cell viability, iron and ROS accumulation, upregulated PTGS2 and MDA levels, reduced glutathione peroxidase 4 (GPX4) levels and significantly mitochondrial damage in VSMCs. Intriguingly, calcium deposition in VSMCs could be reversed by the ferroptosis inhibitor ferrostatin-1. LCN2 expression was significantly upregulated both in the aorta of mice and calcified VSMCs. Compared with WT mice, deletion of LCN2 inhibited cardiovascular calcification whereas VSMC-targeted LCN2 overexpression aggravated CKD-CVC. Consistently, LCN2 knockdown also alleviated calcium deposition of VSMCs. Meanwhile, inhibition of ferroptosis were observed after LCN2 silencing as evidenced by decreased ferrous and lipid oxidation while increased levels of GPX4. Mechanically, we demonstrated high phosphate increased the protein level of NCOA4 and downregulated FTH1, which was reversed by depletion of LCN2. Knockdown of NCOA4 partly alleviated the ferritin reduction, ferroptosis, and calcification in VSMCs, indicating that NCOA4-mediated ferritinophagy was required for VSMCs calcification. Furthermore, we found that the recombinant LCN2 treatment significantly upregulated phosphorylated STAT3. STAT3 signaling inhibitor abolished the recombinant LCN2 induced NCOA4 upregulation and calcification in VSMCs. Conclusion Our findings indicate that the pro-calcific effect of high phosphate is due to VSMCs ferroptosis mediated by LCN2 upregulation. LCN2 silencing alleviates CKD-CVC by suppressing the STAT3/ NCOA4/FTH1 signaling mediated ferritinophagy. LCN2 could serve as a candidate therapeutic strategy for CKD-CVC.

Chemical constitutents and chemotaxonomic research of the deep-sea-derived fungus Talaromyces minioluteus W19

Talaromyces minioluteus W19 was isolated from a deep-sea sediment sample of the western Pacific Ocean. A systematic investigation of its chemical constituents led to the isolation of nine compounds, including one new macrolactin (1), three citrinin (2−4), one sesquiterpene ester (5), one steroid (6), two fatty acid analogues (7 and 8), and one glyceride (9). Compounds 2, 4, and 6−9 were isolated from the genus Talaromyces for the first time. Fusarimone A (3) could be ideal chemotaxonomic marker for T. minioluteus. Drimane sesquiterpenoid-amino acid hybrid is potent chemotaxonomic marker for the genus Talaromyces.

The inositol-requiring enzyme 1 (IRE1) endoplasmic reticulum stress pathway promotes MDA-MB-231 cell survival and renewal in response to the aryl-ureido fatty acid CTU

Current treatment options for triple-negative breast cancer (TNBC) are limited to toxic drug combinations of low efficacy. We recently identified an aryl-substituted fatty acid analogue, termed CTU, that effectively killed TNBC cells in vitro and in mouse xenograft models in vivo without producing toxicity. However, there was a residual cell population that survived treatment. The present study evaluated the mechanisms that underlie survival and renewal in CTU-treated MDA-MB-231 TNBC cells. RNA-seq profiling identified several pro-inflammatory signaling pathways that were activated in treated cells. Increased expression of cyclooxygenase-2 and the cytokines IL-6, IL-8 and GM-CSF was confirmed by real-time RT-PCR, ELISA and Western blot analysis. Increased self-renewal was confirmed using the non-adherent, in vitro colony-forming mammosphere assay. Neutralizing antibodies to IL-6, IL-8 and GM-CSF, as well as cyclooxygenase-2 inhibition suppressed the self-renewal of MDA-MB-231 cells post-CTU treatment. IPA network analysis identified major NF-κB and XBP1 gene networks that were activated by CTU; chemical inhibitors of these pathways and esiRNA knock-down decreased the production of pro-inflammatory mediators. NF-κB and XBP1 signaling was in turn activated by the endoplasmic reticulum (ER)-stress sensor inositol-requiring enzyme 1 (IRE1), which mediates the unfolded protein response. Co-treatment with an inhibitor of IRE1 kinase and RNase activities, decreased phospho-NF-κB and XBP1s expression and the production of pro-inflammatory mediators. Further, IRE1 inhibition also enhanced apoptotic cell death and prevented the activation of self-renewal by CTU. Taken together, the present findings indicate that the IRE1 ER-stress pathway is activated by the anti-cancer lipid analogue CTU, which then activates secondary self-renewal in TNBC cells.

A novel fatty acid analogue triggers CD36–GPR120 interaction and exerts anti-inflammatory action in endotoxemia

Inflammation is a mediator of a number of chronic pathologies. We synthesized the diethyl (9Z,12Z)-octadeca-9,12-dien-1-ylphosphonate, called NKS3, which decreased lipopolysaccharide (LPS)-induced mRNA upregulation of proinflammatory cytokines (IL-1β, IL-6 and TNF-α) not only in primary intraperitoneal and lung alveolar macrophages, but also in freshly isolated mice lung slices. The in-silico studies suggested that NKS3, being CD36 agonist, will bind to GPR120. Co-immunoprecipitation and proximity ligation assays demonstrated that NKS3 induced protein–protein interaction of CD36 with GPR120in RAW 264.7 macrophage cell line. Furthermore, NKS3, via GPR120, decreased LPS-induced activation of TAB1/TAK1/JNK pathway and the LPS-induced mRNA expression of inflammatory markers in RAW 264.7 cells. In the acute lung injury model, NKS3 decreased lung fibrosis and inflammatory cytokines (IL-1β, IL-6 and TNF-α) and nitric oxide (NO) production in broncho-alveolar lavage fluid. NKS3 exerted a protective effect on LPS-induced remodeling of kidney and liver, and reduced circulating IL-1β, IL-6 and TNF-α concentrations. In a septic shock model, NKS3 gavage decreased significantly the LPS-induced mortality in mice. In the last, NKS3 decreased neuroinflammation in diet-induced obese mice. Altogether, these results suggest that NKS3 is a novel anti-inflammatory agent that could be used, in the future, for the treatment of inflammation-associated pathologies.

Differential scanning fluorimetry to assess PFAS binding to bovine serum albumin protein.

The rapid screening of protein binding affinity for poly- and perfluoroalkyl substances (PFAS) benefits risk assessment and fate and transport modelling. PFAS are known to bioaccumulate in livestock through contaminated food and water. One excretion pathway is through milk, which may be facilitated by binding to milk proteins such as bovine serum albumin (BSA). We report a label-free differential scanning fluorimetry approach to determine PFAS-BSA binding over a broad temperature range. This method utilizes the tryptophan residue within the protein binding pocket as an intrinsic fluorophore, eliminating the need for fluorophore labels that may influence binding. BSA association constants were determined by (a) an equilibrium-based model at the melting temperature of BSA and (b) the Hill adsorption model to account for temperature dependent binding and binding cooperativity. Differences in binding between PFAS and fatty acid analogs revealed that a combination of size and hydrophobicity drives PFAS binding.

Abstract A090: An inflammatory adipose microenvironment promotes ovarian cancer tumor growth and cisplatin resistance

Abstract Epithelial ovarian cancer (EOC) commonly targets the omentum, an adipocyte rich organ of the peritoneum. Omental adipocytes have been shown to promote EOC development and chemoresistance via transfer of free fatty acids (FFAs) and the induction of bi-directional metabolic changes. Furthermore, obesity and adiposity are risk factors for EOC incidence and prognosis. The metastatic peritoneal tumor microenvironment (TME) is highly inflamed, while obesity is often characterized by chronic inflammation of adipose tissue and hyperlipidemia. Given that inflammation of adipocytes is associated with increased release of FFAs, we hypothesized that acute inflammation in the ovarian metastatic TME exacerbates pro-tumorigenic effects of cancer-associated adipocytes. Using a three-dimensional transwell co-culture model, we explore the impact of inflamed adipocytes on EOC activity. Adipocytes generated from human adipose-derived stem cells were inflamed with 100ng/ml TNFα and cultured alongside tumor spheroids generated from EOC cell lines. Cytokine abundance in serum samples from ovarian cancer patients undergoing cisplatin treatment were also analyzed. We found that inflammation of adipocytes increased cellular lipolysis and release of FFAs, as well as inducing de-differentiation and loss of lipid droplets. Upon co-culture with inflamed adipocytes, EOC cells displayed increased proliferation in 2D monolayer and 3D spheroid cultures. Transfer of FFAs from adipocytes to cancer cells was visualized and quantified using a fluorescent fatty acid analog via confocal microscopy and flow cytometry. Co-culture induced expression of fatty acid chaperone protein FABP4 in EOC cell lines, while blocking fatty acid metabolism in cancer cells reversed pro-tumor effects of adipocytes. To understand signaling mechanisms generating bi-directional phenotypic changes, cytokine content of secretome of co-cultures was assessed by Luminex. IL-6 and IL-8 were highly abundant in co-cultures, and increased expression was confirmed by qPCR. Treatment of EOC cell lines with recombinant IL-6 and IL-8 induced increased uptake of FFAs and blocking of IL-6 and IL-8 signaling reversed pro-cancer effects of adipocytes. Serum samples from patients undergoing cisplatin therapy were analyzed and IL-6 and IL-8 levels were found to be associated with resistance to therapy. To further investigate the impact of inflamed adipocyte signaling on therapeutic resistance, co-culture were treated with cisplatin and tumor spheroids were found to be highly resistant in the presence of inflamed adipocytes. STAT3 activity is known to be upregulated by both IL-6 and IL-8 and we found that STAT3 expression was increased in co-cultures. Knockdown of STAT3 in EOC reversed the chemoprotective effects of inflamed adipocytes. These data suggest an important role for inflammation of adipose tissue in the development of therapeutic resistance in EOC and highlight a potential mechanism linking clinically observed associations between obesity and ovarian cancer risk. Citation Format: Michael E. Williams, David Howard, Deyarina Gonzalez, Francesca Taraballi. An inflammatory adipose microenvironment promotes ovarian cancer tumor growth and cisplatin resistance [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr A090.

Structure-Activity Relationship Studies and Optimization of 4-Hydroxypyridones as GPR84 Agonists.

GPR84 is a putative medium-chain fatty acid receptor that is implicated in regulation of inflammation and fibrogenesis. Studies have indicated that GPR84 agonists may have therapeutic potential in diseases such as Alzheimer's disease, atherosclerosis, and cancer, but there is a lack of quality tool compounds to explore this potential. The fatty acid analogue LY237 (4a) is the most potent GPR84 agonist disclosed to date but has unfavorable physicochemical properties. We here present a SAR study of 4a. Several highly potent agonists were identified with EC50 down to 28 pM, and with SAR generally in excellent agreement with structure-based modeling. Proper incorporation of rings and polar groups resulted in the identification of TUG-2099 (4s) and TUG-2208 (42a), both highly potent GPR84 agonists with lowered lipophilicity and good to excellent solubility, in vitro permeability, and microsomal stability, which will be valuable tools for exploring the pharmacology and therapeutic prospects of GPR84.

Evidence for a role of SNMP2 and antennal support cells in sensillum lymph clearance processes of moth pheromone-responsive sensilla

In insect antenna, following the activation of olfactory sensory neurons, odorant molecules are inactivated by enzymes in the sensillum lymph. How the inactivation products are cleared from the sensillum lymph is presently unknown. Here we studied the role of support cells (SCs) and the so-called sensory neuron membrane protein 2 (SNMP2), a member of the CD36 family of lipid transporters abundantly expressed in SCs, in sensillum lymph clearance processes in the moths Heliothis virescens and Bombyx mori. In these species, the sex pheromone components are inactivated to long-chain fatty acids. To approach a role of SNMP2 in the removal of such inactivation products, we analyzed the uptake of a fluorescent long-chain fatty acid analog into a newly generated HvirSNMP2-expressing cell line. We found an increased uptake of the analog into SNMP2-cells compared to control cells, which could be blocked by the CD36 protein inhibitor, SSO. Furthermore, analyses of sensilla from antenna treated with the fatty acid analog indicated that SNMP2-expressing SCs are able to take up fatty acids from the sensillum lymph. In addition, sensilla from SSO-pretreated antenna of B. mori showed reduced removal of the fluorescent analog from the sensillum lymph. Finally, we revealed that SSO pretreatment of male silkmoth antenna significantly prolonged the duration of the female pheromone-induced wing-fluttering behavior, possibly as a result of impaired lymph clearance processes. Together our findings in H. virescens and B. mori support a pivotal role of olfactory SCs in sensillum lymph maintenance processes and suggest an integral role of SNMP2 in the removal of lipophilic “waste products” such as fatty acids resulting from sex pheromone inactivation.

A medium-chain fatty acid analogue prevents hepatosteatosis and decreases inflammatory lipid metabolites in a murine model of parenteral nutrition-induced hepatosteatosis.

Parenteral (intravenous) nutrition is lifesaving for patients with intestinal failure, but long-term use of parenteral nutrition often leads to liver disease. SEFA-6179 is a synthetic medium-chain fatty acid analogue designed to target multiple fatty acid receptors regulating metabolic and inflammatory pathways. We hypothesized that SEFA-6179 would prevent hepatosteatosis and lipotoxicity in a murine model of parenteral nutrition-induced hepatosteatosis. Two in vivo experiments were conducted. In the first experiment, six-week-old male mice were provided an ad lib fat-free high carbohydrate diet (HCD) for 19 days with orogastric gavage of either fish oil, medium-chain triglycerides, or SEFA-6179 at a low (0.3mmol/kg) or high dose (0.6mmol/kg). In the second experiment, six-week-old mice were provided an ad lib fat-free high carbohydrate diet for 19 days with every other day tail vein injection of saline, soybean oil lipid emulsion, or fish oil lipid emulsion. Mice then received every other day orogastric gavage of medium-chain triglyceride vehicle or SEFA-6179 (0.6mmol/kg). Hepatosteatosis was assessed by a blinded pathologist using an established rodent steatosis score. Hepatic lipid metabolites were assessed using ultra-high-performance liquid chromatography-mass spectrometry. Effects of SEFA-6179 on fatty acid oxidation, lipogenesis, and fatty acid uptake in human liver cells were assessed in vitro. In the first experiment, mice receiving the HCD with either saline or medium-chain triglyceride treatment developed macrovesicular steatosis, while mice receiving fish oil or SEFA-6179 retained normal liver histology. In the second experiment, mice receiving a high carbohydrate diet with intravenous saline or soybean oil lipid emulsion, along with medium chain triglyceride vehicle treatment, developed macrovescular steatosis. Treatment with SEFA-6179 prevented steatosis. In each experiment, SEFA-6179 treatment decreased arachidonic acid metabolites as well as key molecules (diacylglycerol, ceramides) involved in lipotoxicity. SEFA-6179 increased both β- and complete fatty oxidation in human liver cells, while having no impact on lipogenesis or fatty acid uptake. SEFA-6179 treatment prevented hepatosteatosis and decreased toxic lipid metabolites in a murine model of parenteral nutrition-induced hepatosteatosis. An increase in both β- and complete hepatic fatty acid oxidation may underlie the reduction in steatosis.

Effect of probenecid on blood levels and renal elimination of furosemide and endogenous compounds in rats: Discovery of putative organic anion transporter biomarkers

Transporter-mediated drug-drug interactions (DDIs) are assessed using probe drugs and in vitro and in vivo models during drug development. The utility of endogenous metabolites as transporter biomarkers is emerging for prediction of DDIs during early phases of clinical trials. Endogenous metabolites such as pyridoxic acid and kynurenic acid have shown potential to predict DDIs mediated by organic anion transporters (OAT1 and OAT3). However, these metabolites have not been assessed in rats as potential transporter biomarkers. We carried out a rat pharmacokinetic DDI study using probenecid and furosemide as OAT inhibitor and substrate, respectively. Probenecid administration led to a 3.8-fold increase in the blood concentrations and a 3-fold decrease in renal clearance of furosemide. High inter-individual and intra-day variability in pyridoxic acid and kynurenic acid, and no or moderate effect of probenecid administration on these metabolites suggest their limited utility for prediction of Oat-mediated DDI in rats. Therefore, rat blood and urine samples were further analysed using untargeted metabolomics. Twenty-one m/z features (out of >8000 detected features) were identified as putative biomarkers of rat Oat1 and Oat3 using a robust biomarker qualification approach. These m/z features belong to metabolic pathways such as fatty acid analogues, peptides, prostaglandin analogues, bile acid derivatives, flavonoids, phytoconstituents, and steroids, and can be used as a panel to decrease variability caused by processes other than Oats. When validated, these putative biomarkers will be useful in predicting DDIs caused by Oats in rats.

Absorption of an engineered medium-chain fatty acid analogue in two short bowel syndrome minipig models.

Enteral drug therapy is challenging in short bowel syndrome with intestinal failure (SBS-IF) because of unpredictable absorption. SEFA-6179 is an enterally administered medium-chain fatty acid analogue under development for intestinal failure-associated liver disease. We investigate the pharmacokinetics of two SEFA-6179 formulations in two large-animal models of SBS-IF, including a new pseudojejunostomy model. Twenty Yucatan minipigs were obtained. Half underwent pre-resection pharmacokinetic study with single-dose SEFA-6179 administration. All minipigs then underwent 90% jejunoileal resection, with either a jejunoileal anastomosis or bypass of the intraperitoneal colon with anastomosis just proximal to the rectum (pseudojejunostomy). On postoperative day 3, a single-dose pharmacokinetic study was performed. Both SBS-IF models were well tolerated. Compared with the jejunoileal anastomosis minipigs, pseudojejunostomy minipigs had a more severe malabsorptive phenotype with weight loss by postoperative day 4 (+0.1 vs -0.9 kg, P = 0.03) and liquid diarrhea (Bristol 5 vs Bristol 7, P = 0.0007). Compared with pre-resection minipigs, both jejunoileal and pseudojejunostomy minipigs had lower total plasma exposure of SEFA-6179 measured by area under the curve (jejunoileal: 37% less, P = 0.049; pseudojejunostomy: 74% less, P = 0.0001). Peak plasma concentration was also lower in the pseudojejunostomy group compared with pre-resection (65% less, P = 0.04), but not lower in the jejunoileal group (P = 0.47). In two SBS-IF minipig models, SEFA-6179 had substantially decreased absorption compared with pre-resection minipigs. Dose optimization for different intestinal anatomy and function may be required. We describe a new SBS-IF pseudojejunostomy model that may improve the translation of preclinical research to patients with SBS-IF who have enterostomies.

Rare diphenylheptanoid-phenylheptanoid hybrids with α-glucosidase inhibitory effects from the pollen of Typha angustifolia

Two rarely occurring diphenylheptanoid-phenylheptanoid hybrid dimers (1 and 2) and one new oxygenated fatty acid (3), as well as two known fatty acid analogues (4 and 5), were isolated from the 70% EtOH extract of the pollen of Typha angustifolia. Their planar structures were established by interpretation of MS and NMR spectroscopic data, and the absolute configurations of 1 and 2 were determined by Mosher’s method and quantum chemical TD-DFT calculations of ECD spectra. An in vitro anti-diabetic evaluation of these isolates revealed that compounds 1 and 2 exhibited promising inhibitory activity against α-glucosidase with IC50 values of 11.85 ± 0.69 and 17.06 ± 3.08 μM, respectively. It is the first report on both diphenylheptanoid constituents and α-glucosidase inhibitors from the title plant, which represents a significant phytochemical progress of this herbal species and may serve as a reference for its future medicinal applications.

Mechanistic understanding of KCNQ1 activating polyunsaturated fatty acid analogs.

The KCNQ1 channel is important for the repolarization phase of the cardiac action potential. Loss of function mutations in KCNQ1 can cause long QT syndrome (LQTS), which can lead to cardiac arrythmia and even sudden cardiac death. We have previously shown that polyunsaturated fatty acids (PUFAs) and PUFA analogs can activate the cardiac KCNQ1 channel, making them potential therapeutics for the treatment of LQTS. PUFAs bind to KCNQ1 at two different binding sites: one at the voltage sensor (Site I) and one at the pore (Site II). PUFA interaction at Site I shifts the voltage dependence of the channel to the left, while interaction at Site II increases maximal conductance. The PUFA analogs, linoleic-glycine and linoleic-tyrosine, are more effective than linoleic acid at Site I, but less effective at Site II. Using both simulations and experiments, we find that the larger head groups of linoleic-glycine and linoleic-tyrosine interact with more residues than the smaller linoleic acid at Site I. We propose that this will stabilize the negatively charged PUFA head group in a position to better interact electrostatically with the positively charges in the voltage sensor. In contrast, the larger head groups of linoleic-glycine and linoleic-tyrosine compared with linoleic acid prevent a close fit of these PUFA analogs in Site II, which is more confined. In addition, we identify several KCNQ1 residues as critical PUFA-analog binding residues, thereby providing molecular models of specific interactions between PUFA analogs and KCNQ1. These interactions will aid in future drug development based on PUFA-KCNQ1 channel interactions.

Mechanistic insights into robust cardiac IKs potassium channel activation by aromatic polyunsaturated fatty acid analogues.

Voltage-gated potassium (KV) channels are important regulators of cellular excitability and control action potential repolarization in the heart and brain. KV channel mutations lead to disordered cellular excitability. Loss-of-function mutations, for example, result in membrane hyperexcitability, a characteristic of epilepsy and cardiac arrhythmias. Interventions intended to restore KV channel function have strong therapeutic potential in such disorders. Polyunsaturated fatty acids (PUFAs) and PUFA analogues comprise a class of KV channel activators with potential applications in the treatment of arrhythmogenic disorders such as long QT syndrome (LQTS). LQTS is caused by a loss-of-function of the cardiac IKs channel - a tetrameric potassium channel complex formed by KV7.1 and associated KCNE1 protein subunits. We have discovered a set of aromatic PUFA analogues that produce robust activation of the cardiac IKs channel, and a unique feature of these PUFA analogues is an aromatic, tyrosine head group. We determine the mechanisms through which tyrosine PUFA analogues exert strong activating effects on the IKs channel by generating modified aromatic head groups designed to probe cation-pi interactions, hydrogen bonding, and ionic interactions. We found that tyrosine PUFA analogues do not activate the IKs channel through cation-pi interactions, but instead do so through a combination of hydrogen bonding and ionic interactions.

1611-P: Assessment of Fatty Acid Uptake by PET/MRI Imaging Under Fasting and Postprandial Conditions—A Repeatability Study in People with T2DM and Obesity

Background: Changes in fatty acid metabolism are an important component of the pathogenesis of type 2 diabetes mellitus (T2DM). Fatty acid uptake in tissues can be measured with positron emission tomography (PET) imaging, employing the fatty acid analogue 18F-FTHA radiotracer. We aimed to evaluate the repeatability of assessments of fatty acid uptake in tissues with a new whole-body PET/MRI (magnetic resonance) imaging method in people with obesity with or without T2DM. Methods: 17 completers underwent 4 repeated examinations under standardised conditions, twice under fasting and twice postprandially (PP). Tissue-specific fatty acid uptake (FAU) and uptake rate was measured using 18F-FTHA and dynamic whole-body PET/MRI in skeletal muscle, subcutaneous and visceral adipose tissues (SAT, VAT), myocardium and brain. Free fatty acid levels were measured over time. The repeatability of PET measurements under fasting, and under PP, was assessed by calculating the intraclass correlation coefficient (ICC 2,1) along with its 95 % confidence intervals; ICC ≥ 0.75 indicates excellent, 0.6 - 0.74 good, 0.4 - 0.59 fair and <0.4 poor reliability. Results: In the fasted state, repeatability of the net uptake rate in muscle tissue was found to be excellent, ICC 0.91 (0.78 - 0.96) and good in myocardium, ICC 0.64 (0.27-0.86). Repeatability of FAU in other tissues was at least fair (ICC SAT 0.80 (0.54-0.91), VAT 0.64 (0.27-0.85), brain 0.75 (0.46-0.90). In the PP experiments, variability increased especially for the FAU estimates, but the repeatability of the uptake rate was acceptable (ICC >0.4) for most investigated tissues, and good for muscle (ICC 0.73 (0.42-0.89). Conclusion: 18F-FTHA-PET/MRI provides information on tissue-specific fatty acid uptake with good reliability, and excellent repeatability for the muscle under fasting. The method has potential to provide insights in monitoring and evaluating treatment effects in interventional trials. Disclosure I.Laitinen: Employee; Antaros Medical. T.Coskun: Employee; Eli Lilly and Company, Stock/Shareholder; Eli Lilly and Company. Z.Milicevic: Employee; Eli Lilly and Company. L.Johansson: Employee; Antaros Medical, Stock/Shareholder; Antaros Medical. P.Nuutila: None. S.Ekström: Employee; Antaros Medical. H.Haraldsson: Employee; Antaros Medical. S.Pierrou: Stock/Shareholder; AstraZeneca. K.Kalliokoski: Consultant; Synektik S.A., Stock/Shareholder; Faron Pharmaceuticals Oy, CRST Oy. M.Kiugel: None. M.Scheinin: Consultant; Orion Pharma, Employee; Clinical Research Services Turku - CRST Oy, Other Relationship; Antaros Medical AB, Biogen, Boehringer Ingelheim International GmbH, Falk GmbH and Co Kg, Imbria, Novartis AG, Novo Nordisk A/S, Provention Bio, Inc., Stock/Shareholder; Clinical Research Services Turku - CRST Oy. S.Southekal: Employee; Eli Lilly and Company. M.Lu: None.

A Medium-Chain Fatty Acid Analogue Prevents Intestinal Failure–Associated Liver Disease in Preterm Yorkshire Piglets

At least 20%-30% of patients with intestinal failure receiving long-term parenteral nutrition will develop intestinal failure-associated liver disease (IFALD), for which there are few therapeutic options. SEFA-6179 is a first-in-class structurally engineered medium-chain fatty acid analogue that acts through GPR84, PPARα, and PPARγ agonism. We hypothesized that SEFA-6179 would prevent biochemical and histologic liver injury in a preterm piglet model of IFALD. Preterm Yorkshire piglets were delivered by cesarean section, and parenteral nutrition was provided for 14 days via implanted central venous catheters. Animals were treated with either medium-chain triglyceride vehicle control or SEFA-6179. Compared to medium-chain triglyceride vehicle at day of life 15, SEFA-6179 prevented biochemical cholestasis (direct bilirubin: 1.9 vs <0.2 mg/dL, P= .01; total bilirubin: 2.7 vs 0.4 mg/dL, P= .02; gamma glutamyl transferase: 172 vs 30 U/L, P= .01). SEFA-6179 also prevented steatosis (45.6 vs 13.9 mg triglycerides/g liver tissue, P= .009), reduced bile duct proliferation (1.6% vs 0.5% area cytokeratin 7 positive, P= .009), and reduced fibrosis assessed by a masked pathologist (median Ishak score: 3 vs 1, P= 0.007). RNA sequencing of liver tissue demonstrated that SEFA-6179 broadly impacted inflammatory, metabolic, and fibrotic pathways, consistent with its invitro receptor activity (GPR84/PPARα/PPARγ agonist). In a preterm piglet model of IFALD, SEFA-6179 treatment prevented biochemical cholestasis and steatosis and reduced bile duct proliferation and fibrosis. SEFA-6179 is a promising first-in-class therapy for the prevention and treatment of IFALD that will be investigated in an upcoming phase II clinical trial.