Abscisic acid enriched fig extract promotes insulin sensitivity by decreasing systemic inflammation and activating LANCL2 in skeletal muscle.

Abscisic acid is a phytohormone found in fruits and vegetables and is endogenously produced in mammals. In humans and mice, lanthionine synthetase C-like 2 (LANCL2) has been characterized as the natural receptor for ABA. Herein, we characterize the efficacy of a fig fruit extract of ABA in promoting glycemic control. This ABA-enriched extract, at 0.125 µg ABA/kg body weight, improves glucose tolerance, insulin sensitivity and fasting blood glucose in diet-induced obesity (DIO) and db/db mouse models. In addition to decreasing systemic inflammation and providing glycemic control without increasing insulin, ABA extract modulates the metabolic activity of muscle. ABA increases expression of important glycogen synthase, glucose, fatty acid and mitochondrial metabolism genes and increases direct measures of fatty acid oxidation, glucose oxidation and metabolic flexibility in soleus muscle cells from ABA-treated mice with DIO. Glycolytic and mitochondrial ATP production were increased in ABA-treated human myotubes. Further, ABA synergized with insulin to dramatically increase the rate of glycogen synthesis. The loss of LANCL2 in skeletal muscle abrogated the effect of ABA extract in the DIO model and increased fasting blood glucose levels. This data further supports the clinical development of ABA in the treatment of pre-diabetes, type 2 diabetes and metabolic syndrome.

Abscisic Acid Standardized Fig (Ficus carica) Extracts Ameliorate Postprandial Glycemic and Insulinemic Responses in Healthy Adults.

Abscisic acid (ABA) can improve glucose homeostasis and reduce inflammation in mammals by activating lanthionine synthetase C-like 2 (LANCL2). This study examined the effects of two fig fruit extracts (FFEs), each administered at two different ABA doses, on glycemic index (GI) and insulinemic index (II) to a standard glucose drink. In a randomized, double-blind crossover study, 10 healthy adults consumed 4 test beverages containing FFE with postprandial glucose and insulin assessed at regular intervals over 2 h to determine GI and II responses. Test beverages containing 200 mg FFE-50× and 1200 mg FFE-10× significantly reduced GI values by -25% (P = 0.001) and -24% (P = 0.002), respectively. Two lower doses of FFE also reduced GI values compared with the reference drink (by approximately -14%), but the differences did not reach statistical significance. Addition of FFE to the glucose solution significantly reduced II values at all dosages and displayed a clear dose-response reduction: FFE-50× at 100 mg and 200 mg (-14% (P < 0.05) and -24% (P = 0.01), respectively) and FFE-10× at 600 mg and 1200 mg (-16% (P < 0.05) and -24% (P = 0.01), respectively). FFE supplementation is a promising nutritional intervention for the management of acute postprandial glucose and insulin homeostasis, and it is a possible adjunctive treatment for glycemic management of chronic metabolic disorders such as prediabetes and type 2 diabetes mellitus.

Nonclinical Toxicology and Toxicokinetic Profile of an Oral Lanthionine Synthetase C-Like 2 (LANCL2) Agonist, BT-11.

BT-11 is an orally active, gut-restricted investigational therapeutic targeting the lanthionine synthetase C-like 2 pathway with lead indications in ulcerative colitis (UC) and Crohn disease (CD), 2 manifestations of inflammatory bowel disease (IBD). In 5 mouse models of IBD, BT-11 is effective at oral doses of 8 mg/kg. BT-11 was also efficacious at nanomolar concentrations in primary human samples from patients with UC and CD. BT-11 was tested under Good Laboratory Practice conditions in 90-day repeat-dose general toxicity studies in rats and dogs, toxicokinetics, respiratory, cardiovascular and central nervous system safety pharmacology, and genotoxicity studies. Oral BT-11 did not cause any clinical signs of toxicity, biochemical or hematological changes, or macroscopic or microscopic changes to organs in 90-day repeat-dose toxicity studies in rats and dogs at doses up to 1,000 mg/kg/d. Oral BT-11 resulted in low systemic exposure in both rats (area under the curve exposure from t = 0 to t = 8 hours [AUC0-8] of 216 h × ng/mL) and dogs (650 h × ng/mL) and rapid clearance with an average half-life of 3 hours. BT-11 did not induce changes in respiratory function, electrocardiogram parameters, or behavior with single oral doses of 1,000 mg/kg/d. There was no evidence of mutagenic or genotoxic potential for BT-11 up to tested limit doses using an Ames test, chromosomal aberration assay in human peripheral blood lymphocytes, or micronucleus assay in rats. Therefore, nonclinical studies show BT-11 to be a safe and well-tolerated oral therapeutic with potential as a potent immunometabolic therapy for UC and CD with no-observed adverse effect level >1,000 mg/kg in in vivo studies.

NLRX1 Modulates Immunometabolic Mechanisms Controlling the Host-Gut Microbiota Interactions during Inflammatory Bowel Disease.

Interactions among the gut microbiome, dysregulated immune responses, and genetic factors contribute to the pathogenesis of inflammatory bowel disease (IBD). Nlrx1-/- mice have exacerbated disease severity, colonic lesions, and increased inflammatory markers. Global transcriptomic analyses demonstrate enhanced mucosal antimicrobial defense response, chemokine and cytokine expression, and epithelial cell metabolism in colitic Nlrx1-/- mice compared to wild-type (WT) mice. Cell-specificity studies using cre-lox mice demonstrate that the loss of NLRX1 in intestinal epithelial cells (IEC) recapitulate the increased sensitivity to DSS colitis observed in whole body Nlrx1-/- mice. Further, organoid cultures of Nlrx1-/- and WT epithelial cells confirm the altered patterns of proliferation, amino acid metabolism, and tight junction expression. These differences in IEC behavior can impact the composition of the microbiome. Microbiome analyses demonstrate that colitogenic bacterial taxa such as Veillonella and Clostridiales are increased in abundance in Nlrx1-/- mice and in WT mice co-housed with Nlrx1-/- mice. The transfer of an Nlrx1-/--associated gut microbiome through co-housing worsens disease in WT mice confirming the contributions of the microbiome to the Nlrx1-/- phenotype. To validate NLRX1 effects on IEC metabolism mediate gut-microbiome interactions, restoration of WT glutamine metabolic profiles through either exogenous glutamine supplementation or administration of 6-diazo-5-oxo-l-norleucine abrogates differences in inflammation, microbiome, and overall disease severity in Nlrx1-/- mice. The influence NLRX1 deficiency on SIRT1-mediated effects is identified to be an upstream controller of the Nlrx1-/- phenotype in intestinal epithelial cell function and metabolism. The altered IEC function and metabolisms leads to changes in barrier permeability and microbiome interactions, in turn, promoting greater translocation and inflammation and resulting in an increased disease severity. In conclusion, NLRX1 is an immunoregulatory molecule and a candidate modulator of the interplay between mucosal inflammation, metabolism, and the gut microbiome during IBD.

Modeling-Enabled Characterization of Novel NLRX1 Ligands.

Nucleotide-binding domain and leucine-rich repeat containing (NLR) family are intracellular sentinels of cytosolic homeostasis that orchestrate immune and inflammatory responses in infectious and immune-mediated diseases. NLRX1 is a mitochondrial-associated NOD-like receptor involved in the modulation of immune and metabolic responses. This study utilizes molecular docking approaches to investigate the structure of NLRX1 and experimentally assesses binding to naturally occurring compounds from several natural product and lipid databases. Screening of compound libraries predicts targeting of NLRX1 by conjugated trienes, polyketides, prenol lipids, sterol lipids, and coenzyme A-containing fatty acids for activating the NLRX1 pathway. The ligands of NLRX1 were identified by docking punicic acid (PUA), eleostearic acid (ESA), and docosahexaenoic acid (DHA) to the C-terminal fragment of the human NLRX1 (cNLRX1). Their binding and that of positive control RNA to cNLRX1 were experimentally determined by surface plasmon resonance (SPR) spectroscopy. In addition, the ligand binding sites of cNLRX1 were predicted in silico and validated experimentally. Target mutagenesis studies demonstrate that mutation of 4 critical residues ASP677, PHE680, PHE681, and GLU684 to alanine resulted in diminished affinity of PUA, ESA, and DHA to NLRX1. Consistent with the regulatory actions of NLRX1 on the NF-κB pathway, treatment of bone marrow derived macrophages (BMDM)s with PUA and DHA suppressed NF-κB activity in a NLRX1 dependent mechanism. In addition, a series of pre-clinical efficacy studies were performed using a mouse model of dextran sodium sulfate (DSS)-induced colitis. Our findings showed that the regulatory function of PUA on colitis is NLRX1 dependent. Thus, we identified novel small molecules that bind to NLRX1 and exert anti-inflammatory actions.

Effects of task relevance and stimulus-driven salience in feature-search mode.

Attentional allocation in feature-search mode (W. F. Bacon & H. E. Egeth, 1994) is thought to be solely determined by top-down factors, with no role for stimulus-driven salience. The authors reassessed this conclusion using variants of the spatial cuing and rapid serial visual presentation paradigms developed by C. L. Folk and colleagues (C. L. Folk, R. W. Remington, & J. C. Johnston, 1992; C. L. Folk, A. B. Leber, & H. E. Egeth, 2002). They found that (a) a nonsingleton distractor that possesses the target feature produces attentional capture, (b) such capture is modulated by bottom-up salience, and (c) resistance to capture by irrelevant singletons is mediated by inhibitory processes. These results extend the role of top-down factors in search for a nonsingleton target while arguing against the notion that effects of bottom-up salience and top-down factors on attentional priority are strictly encapsulated within distinct search modes.