Development of FABP4/5 inhibitors with potential therapeutic effect on type 2 Diabetes Mellitus

Discovery of the first-in-class FABP/PPAR multiple modulator for the treatment of metabolic dysfunction-associated steatohepatitis

Metabolic dysfunction-associated steatohepatitis (MASH) is a complex metabolic syndrome, and the development of new drugs is urgently needed. Fatty acid binding proteins (FABPs) and peroxisome proliferator-activated receptors (PPARs) play an important role in the regulation of lipid absorption, metabolism and inflammation. Considering the synergistic effect of FABP and PPAR in the regulation of MASH pathophysiology, the development of FABP/PPAR multiple modulators might be a promising anti-MASH strategy. Herein, the first-in-class FABP/PPAR multiple modulators were designed by hybrid resveratrol and PPARs agonist Elafibranor. Among them, the compound 27 was identified as the optimal FABP/PPAR multiple modulator (FABP1 IC50 = 0.65 μM, FABP4 IC50 = 1.08 μM, PPARα EC50 = 9.19 μM, PPARγ EC50 = 2.20 μM, PPARδ EC50 = 1.58 μM). Further MST assay confirmed the direct interaction of compound 27 and FABP1, providing a robust validation of its target specificity. In MASH mice, compound 27 exhibited a better therapeutic effect than clinical candidate obeticholic acid in ameliorating multiple pathological features of MASH. This study reported the successful discovery of the first-in-class FABP/PPAR multiple modulators, which provided preliminary evidence that such multi-target agents have broad medical prospects.

Fatty acid binding proteins-mediated mitochondrial dysfunction in the development of age-related diseases: A review

Fatty acid-binding proteins (FABPs) act as lipid chaperones and play a role in the pathological processes of various lipid signaling pathways. Mitochondria are crucial for the regulation of lipid metabolism. As an aging marker, lipid-mediated mitochondrial dysfunction has been observed in the etiology of numerous diseases, including neurodegenerative diseases, metabolic syndromes, cardiovascular diseases, and tumorigenesis. Members of the FABP family have been identified to regulate mitochondrial function. Targeting FABPs specifically may provide a promising approach to improve mitochondrial function and treat age-related diseases. This review summarizes the connection between FABPs and mitochondrial function and highlights certain FABPs involved in age-related diseases that hold significant therapeutic promise.

Potential safety implications of fatty acid-binding protein inhibition

Fatty acid-binding proteins (FABPs) are small intracellular proteins that regulate fatty acid metabolism, transport, and signalling. There are ten known human isoforms, many of which are upregulated and involved in clinical pathologies. As such, FABP inhibition may be beneficial in disease states such as cancer, and those involving the cardiovascular system, metabolism, immunity, and cognition. Recently, a potent, selective FABP5 inhibitor (ART26.12), with 90-fold selectivity to FABP3 and 20-fold selectivity to FABP7, was found to be remarkably benign, with a no-observed-adverse-effect level of 1000 mg/kg in rats and dogs, showing no genotoxicity, cardiovascular, central, or respiratory toxicity. To understand the potential implication of FABP inhibition more fully, this review systematically assessed literature investigating genetic knockout, knockdown, and pharmacological inhibition of FABP3, FABP4, FABP5, or FABP7. Analysis of the literature revealed that animals bred not to express FABPs showed the most biological effects, suggesting key roles of these proteins during development. FABP ablation sometimes exacerbated symptoms of disease models, particularly those linked to metabolism, inflammatory and immune responses, cardiac contractility, neurogenesis, and cognition. However, FABP inhibition (genetic silencing or pharmacological) had a positive effect in many more disease conditions. Several polymorphisms of each FABP gene have also been linked to pathological conditions, but it was unclear how several polymorphisms affected protein function. Overall, analysis of the literature to date suggests that pharmacological inhibition of FABPs in adults is of low risk.

Design, synthesis, and biological evaluation of first-in-class FABP1 inhibitors for the treatment of NASH

The fatty acid-binding protein 1 (FABP1) is a fatty acid transporter protein that is considered as an emerging target for metabolic diseases. Despite forceful evidence that the inhibition of FABP1 is essential for ameliorating NASH, pharmacological control and validation of FABP1 are hindered by a lack of relevant inhibitors as pharmacological tool. Therefore, the development of effective FABP1 inhibitors is a current focus of research. Herein, we firstly reported the comprehensive structure-activity relationship (SAR) study of novel FABP1 inhibitors derived from high throughput screening of our in-house library, which resulting in the identification of the optimal compound 44 (IC50 = 4.46 ± 0.54 μM). Molecular docking studies revealed that 44 forms stable hydrogen bonds with amino acids around the active pocket of FABP1. Moreover, 44 alleviated the typical histological features of fatty liver in NASH mice, including steatosis, lobular inflammation, ballooning and fibrosis. Additionally, 44 has been demonstrated to have lipid metabolism regulating, anti-oxidative stress and hepatoprotective properties. This study might be provided a promising insight into the field of NASH and inspiration for the development of FABP1 inhibitors.

Recent Advances on Small-Molecule Inhibitors of Lipocalin-like Proteins

Lipid transfer proteins (LTPs) are crucial players in nonvesicular lipid trafficking. LTPs sharing a lipocalin lipid transfer domain (lipocalin-like proteins) have a wide range of biological functions, such as regulating immune responses and cell proliferation, differentiation, and death as well as participating in the pathogenesis of inflammatory, metabolic, and neurological disorders and cancer. Therefore, the development of small-molecule inhibitors targeting these LTPs is important and has potential clinical applications. Herein, we summarize the structure and function of lipocalin-like proteins, mainly including retinol-binding proteins, lipocalins, and fatty acid-binding proteins and discuss the recent advances on small-molecule inhibitors for these protein families and their applications in disease treatment. The findings of our Perspective can provide guidance for the development of inhibitors of these LTPs and highlight the challenges that might be faced during the procedures.

Structure-based design of potent FABP4 inhibitors with high selectivity against FABP3

Fatty-acid binding protein 4 (FABP4) presents an attractive target for therapeutic intervention in metabolic and inflammatory diseases in recent years. However, highly similar three-dimensional structures and fatty acid binding ability of multiple FABP family members pose a significant challenge in design of FABP4-selective inhibitors. Particularly, inhibition of FABP3 raises safety concerns such as cardiac dysfunction and exercise intolerance. Here, we reported the discovery of new FABP4 inhibitors with high selectivity over FABP3 by exploiting the little structural difference in the ligand binding pockets of FABP4 and FABP3. On the basis of our previously reported FABP4 inhibitors with nanomolar potency, different substituents were further introduced to perfectly occupy two sub-pockets of FABP4 that are distinct from those of FABP3. Remarkably, a single methyl group introduction leads to the discovery of compound C3 that impressively exhibits a 601-fold selectivity over FABP3 when maintained nanomolar binding affinity for FABP4. Moreover, C3 also shows good metabolic stability and potent cellular anti-inflammatory activity, making it a promising inhibitor for further development. Therefore, the present study highlights the utility of the structure-based rational design strategy for seeking highly selective and potent inhibitors of FABP4 and the importance of identifying the appropriate subsite as well as substituent for gaining the desired selectivity.

Proteomic architecture of frailty across the spectrum of cardiovascular disease

While frailty is a prominent risk factor in an aging population, the underlying biology of frailty is incompletely described. Here, we integrate 979 circulating proteins across a wide range of physiologies with 12 measures of frailty in a prospective discovery cohort of 809 individuals with severe aortic stenosis (AS) undergoing transcatheter aortic valve implantation. Our aim was to characterize the proteomic architecture of frailty in a highly susceptible population and study its relation to clinical outcome and systems-wide phenotypes to define potential novel, clinically relevant frailty biology. Proteomic signatures (specifically of physical function) were related to post-intervention outcome in AS, specifying pathways of innate immunity, cell growth/senescence, fibrosis/metabolism, and a host of proteins not widely described in human aging. In published cohorts, the "frailty proteome" displayed heterogeneous trajectories across age (20-100 years, age only explaining a small fraction of variance) and were associated with cardiac and non-cardiac phenotypes and outcomes across two broad validation cohorts (N > 35,000) over ≈2-3 decades. These findings suggest the importance of precision biomarkers of underlying multi-organ health status in age-related morbidity and frailty.

Optimization of potent, selective and orally bioavailable biphenyl scaffold as FABP4 inhibitors for anti-inflammation

Fatty-acid binding protein 4 (FABP4) is an essential driver for the progression of metabolic-related inflammatory diseases including obesity, diabetes, atherosclerosis, and various lipid metabolism-related tumors. However, FABP4 inhibitors are not yet available for clinical use, which may be associated with their poor selectivity of FABP3, unsatisfactory efficacy and physicochemical properties. Herein, we reported a systematic optimization of a class of biphenyl scaffold molecules as potent FABP4 inhibitors. Further in vitro and in vivo pharmacokinetic studies identified a selective and orally bioavailable compound 10g, with K_i of 0.51 μM against FABP4, K_i of 33.01 μM against FABP3 and bioavailability F% value of 89.4%. In vivo anti-inflammatory efficacy and multi-organ protection study in LPS-induced inflammatory mice model highlighted the potential of compound 10g as a therapeutic candidate in inflammation-related diseases.

Adipocyte fatty acid binding protein 4 (FABP4) inhibitors. An update from 2017 to early 2022

The fatty acid binding protein 4 (FABP4) is a protein predominantly expressed in macrophages and adipose tissue, where it regulates fatty acids storage and lipolysis and is an essential mediator of inflammation. Small molecule inhibitors of FABP4 have attracted interest following the recent publications of beneficial pharmacological effects of these compounds for the treatment of metabolic syndrome and, more recently, for other pathologies. Since the synthesis of the BMS309403, one of the first selective and effective FABP4 inhibitors, hundreds of other inhibitors have been synthesized (i.e., derivatives of niacin, quinoxaline, aryl-quinoline, bicyclic pyridine, urea, aromatic compounds and other novel heterocyclic compounds). This review updates the recently reported (2017 to early 2022) molecules as adipocyte fatty acid binding protein 4 inhibitors.