New Insights into Bitopic Orthosteric/Allosteric Ligands of Cannabinoid Receptor Type 2.

Very recently, we have developed a new generation of ligands targeting the cannabinoid receptor type 2 (CB2R), namely JR compounds, which combine the pharmacophoric portion of the CB2R positive allosteric modulator (PAM), EC21a, with that of the CB2R selective orthosteric agonist LV62, both synthesized in our laboratories. The functional examination enabled us to identify JR14a, JR22a, and JR64a as the most promising compounds of the series. In the current study, we focused on the assessment of the bitopic (dualsteric) nature of these three compounds. Experiments in cAMP assays highlighted that only JR22a behaves as a CB2R bitopic (dualsteric) ligand. In parallel, computational studies helped us to clarify the binding mode of these three compounds at CB2R, confirming the bitopic (dualsteric) nature of JR22a. Finally, the potential of JR22a to prevent neuroinflammation was investigated on a human microglial cell inflammatory model.

Neighborhood poverty is associated with failure to be waitlisted and death during liver transplantation evaluation.

Liver transplantation (LT) is the final step in a complex care cascade. Little is known about how race, gender, rural versus urban residence, or neighborhood socioeconomic indicators impact a patient's likelihood of LT waitlisting or risk of death during LT evaluation. We performed a retrospective cohort study of adults referred for LT to the Indiana University Academic Medical Center from 2011 to 2018. Neighborhood socioeconomic status indicators were obtained by linking patients' addresses to their census tract defined in the 2017 American Community Survey. Descriptive statistics were used to describe completion of steps in the LT evaluation cascade. Multivariable analyses were performed to assess the factors associated with waitlisting and death during LT evaluation. There were 3454 patients referred for LT during the study period; 25.3% of those referred were waitlisted for LT. There was no difference seen in the proportion of patients from vulnerable populations who progressed to the steps of financial approval or evaluation start. There were differences in waitlisting by insurance type (22.6% of Medicaid vs. 34.3% of those who were privately insured; p < 0.01) and neighborhood poverty (quartile 1 29.6% vs. quartile 4 20.4%; p < 0.01). On multivariable analysis, neighborhood poverty was independently associated with waitlisting (odds ratio 0.56, 95% confidence interval [CI] 0.38-0.82) and death during LT evaluation (hazard ratio 1.49, 95% CI 1.09-2.09). Patients from high-poverty neighborhoods are at risk of failing to be waitlisted and death during LT evaluation.

Synthesis and In Vitro Characterization of Selective Cannabinoid CB2 Receptor Agonists: Biological Evaluation against Neuroblastoma Cancer Cells.

1,8-naphthyridine-3-carboxamide structures were previously identified as a promising scaffold from which to obtain CB2R agonists with anticancer and anti-inflammatory activity. This work describes the synthesis and functional characterization of new 1,8-naphthyridin-2(1H)-one-3-carboxamides with high affinity and selectivity for CB2R. The new compounds were able to pharmacologically modulate the cAMP response without modulating CB2R-dependent ß-arrestin2 recruitment. These structures were also evaluated for their anti-cancer activity against SH-SY5Y and SK-N-BE cells. They were able to reduce the cell viability of both neuroblastoma cancer cell lines with micromolar potency (IC50 of FG158a = 11.8 µM and FG160a = 13.2 µM in SH-SY5Y cells) by a CB2R-mediated mechanism. Finally, in SH-SY5Y cells one of the newly synthesized compounds, FG158a, was able to modulate ERK1/2 expression by a CB2R-mediated effect, thus suggesting that this signaling pathway might be involved in its potential anti-cancer effect.

Trends in Racial and Ethnic Disparities in the Receipt of Lifesaving Procedures for Hospitalized Patients With Decompensated Cirrhosis in the US, 2009-2018.

Importance: Patients with decompensated cirrhosis are hospitalized for acute management with temporizing and lifesaving procedures. Published data to inform intervention development in this area are more than a decade old, and it is not clear whether there have been improvements in disparities in the receipt of these procedures over time. Objective: To evaluate the associations of race and ethnicity with receipt of procedures to treat decompensated cirrhosis over time in the US. Design, Setting, and Participants: This retrospective cross-sectional study analyzed National Inpatient Sample data on cirrhosis admissions among patients with portal hypertension-related complications from 2009 to 2018. All hospital discharges for individuals aged 18 years and older from 2009 to 2018 were assessed for inclusion. Admissions were included if they contained at least 1 cirrhosis-related International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) or International Statistical Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) code and at least 1 cirrhosis-related complication ICD-9-CM or ICD-10-CM code (ie, ascites, hepatic encephalopathy, variceal hemorrhage [VH], and hepatorenal syndrome [HRS]). Data were analyzed from January to June 2022. Exposure: Hospitalization for decompensated cirrhosis. Main Outcomes and Measures: The outcomes of interest were trends in the odds ratios (ORs) for receiving procedures (upper endoscopy, transjugular portosystemic shunt [TIPS], hemodialysis, and liver transplantation [LT]) for decompensated cirrhosis and mortality by race and ethnicity, modeled over time. Multivariable logistic regression was used to assess these outcomes. Results: Among 717 580 admissions (median [IQR] age, 58 [52-67] years), 345 644 patients (9.8%) were Black, 623 991 patients (17.6%) were Hispanic, and 2 340 031 patients (47.4%) were White. Based on the modeled trends, by 2018, there were no significant differences by race or ethnicity in the odds of receiving upper endoscopy for VH. However, Black patients remained less likely than White patients to undergo TIPS for VH (OR, 0.54; 95% CI, 0.47-0.62) and ascites (OR, 0.34; 95% CI, 0.31-0.38). The disparity in receipt of LT improved for Black and Hispanic patients over the study period; however, by 2018, both groups remained less likely to undergo LT than their White counterparts (Black: OR, 0.66; 95% CI, 0.61-0.70; Hispanic: OR, 0.74; 95% CI, 0.70-0.78). The odds of death in Black and Hispanic patients declined over the study period but remained higher in Black patients than White patients in 2018 (OR, 1.08; 95% CI, 1.05-1.11). Conclusions and Relevance: In this cross-sectional study of individuals hospitalized with decompensated cirrhosis, there were racial and ethnic disparities in receipt of complex lifesaving procedures and in mortality that persisted over time.

Design, synthesis and biological evaluation of novel orthosteric-allosteric ligands of the cannabinoid receptor type 2 (CB2R).

It is well known that G protein-coupled receptors (GPCRs) assume multiple active states. Orthosteric ligands and/or allosteric modulators can preferentially stabilize specific conformations, giving rise to pathway-biased signaling. One of the most promising strategies to expand the repertoire of signaling-selective GPCR activators consists of dualsteric agents, which are hybrid compounds consisting of orthosteric and allosteric pharmacophoric units. This approach proved to be very promising showing several advantages over monovalent targeting strategies, including an increased affinity or selectivity, a bias in signaling pathway activation, reduced off-target activity and therapeutic resistance. Our study focused on the cannabinoid receptor type 2 (CB2R), considered a clinically promising target for the control of brain damage in neurodegenerative disorders. Indeed, CB2R was found highly expressed in microglial cells, astrocytes, and even in some neuron subpopulations. Here, we describe the design, synthesis, and biological evaluation of two new classes of potential dualsteric (bitopic) CB2R ligands. The new compounds were obtained by connecting, through different linkers, the pharmacophoric portion of the CB2R positive allosteric modulator (PAM), EC21a, with that of the CB2R selective orthosteric agonist LV62, both developed in our laboratories. A preliminary screening enabled us to identify compound JR64a as the most promising of the series. Indeed, functional examination highlighted a signaling 'bias' in favor of G protein activation over ßarrestin2 recruitment, combined with high affinity for CB2R and the ability to efficiently prevent inflammation in human microglial cells (HMC3) exposed to LPS/TNFα stimulation, thus demonstrating great promise for the treatment of neurodegenerative diseases.

Novel Potent and Selective Agonists of the GPR55 Receptor Based on the 3-Benzylquinolin-2(1H)-One Scaffold.

A growing body of evidence underlines the crucial role of GPR55 in physiological and pathological conditions. In fact, GPR55 has recently emerged as a therapeutic target for several diseases, including cancer and neurodegenerative and metabolic disorders. Several lines of evidence highlight GPR55's involvement in the regulation of microglia-mediated neuroinflammation, although the exact molecular mechanism has not been yet elucidated. Nevertheless, there are only a limited number of selective GPR55 ligands reported in the literature. In this work, we designed and synthesized a series of novel GPR55 ligands based on the 3-benzylquinolin-2(1H)-one scaffold, some of which showed excellent binding properties (with Ki values in the low nanomolar range) and almost complete selectivity over cannabinoid receptors. The full agonist profile of all the new derivatives was assessed using the p-ERK activation assay and a computational study was conducted to predict the key interactions with the binding site of the receptor. Our data outline a preliminary structure-activity relationship (SAR) for this class of molecules at GPR55. Some of our compounds are among the most potent GPR55 agonists developed to date and could be useful as tools to validate this receptor as a therapeutic target.

Design, Synthesis, and Biological Activity of New CB2 Receptor Ligands: from Orthosteric and Allosteric Modulators to Dualsteric/Bitopic Ligands.

The design of dualsteric/bitopic agents as single chemical entities able to simultaneously interact with both the orthosteric and an allosteric binding site represents a novel approach in medicinal chemistry. Biased dualsteric/bitopic agents could enhance certain signaling pathways while diminishing the others that cause unwanted side effects. We have designed, synthesized, and functionally characterized the first CB2R heterobivalent bitopic ligands. In contrast to the parent orthosteric compound, our bitopic ligands selectively target CB2R versus CB1R and show a functional selectivity for the cAMP signaling pathway versus ßarrestin2 recruitment. Moreover, the most promising bitopic ligand FD-22a displayed anti-inflammatory activity in a human microglial cell inflammatory model and antinociceptive activity in vivo in an experimental mouse model of neuropathic pain. Finally, computational studies clarified the binding mode of these compounds inside the CB2R, further confirming their bitopic nature.

Variously substituted 2-oxopyridine derivatives: Extending the structure-activity relationships for allosteric modulation of the cannabinoid CB2 receptor.

We previously reported the 2-oxopyridine-3-carboxamide derivative EC21a as the first small synthetic CB2R positive allosteric modulator which displayed antinociceptive activity in vivo in an experimental mouse model of neuropathic pain. Herein, we extended the structure-activity relationships of EC21a through structural modifications regarding the p-fluoro benzyl moiety at position 1 and the amide group in position 3 of the central core. The characterization in vitro was assessed through radioligand binding experiments and functional assays (GTPγS, cAMP, ßarrestin2). Among the new compounds, the derivatives A1 (SV-10a) and A5 (SB-13a) characterized respectively by fluorine atom or by chlorine atom in ortho position of the benzylic group at position 1 and by a cycloheptane-carboxamide at position 3 of the central core, showed positive allosteric behavior on CB2R. They enhanced the efficacy of CP55,940 in [35S]GTPγS assay, and modulated CP55,940-dependent ßarrestin2 recruitment and cAMP inhibition. The obtained results extend our knowledge of the structural requirements for interaction with the allosteric site of CB2R.

In vitro and in vivo pharmacological activity of minor cannabinoids isolated from Cannabis sativa.

The Cannabis sativa plant contains more than 120 cannabinoids. With the exceptions of ∆9-tetrahydrocannabinol (∆9-THC) and cannabidiol (CBD), comparatively little is known about the pharmacology of the less-abundant plant-derived (phyto) cannabinoids. The best-studied transducers of cannabinoid-dependent effects are type 1 and type 2 cannabinoid receptors (CB1R, CB2R). Partial agonism of CB1R by ∆9-THC is known to bring about the 'high' associated with Cannabis use, as well as the pain-, appetite-, and anxiety-modulating effects that are potentially therapeutic. CB2R activation by certain cannabinoids has been associated with anti-inflammatory activities. We assessed the activity of 8 phytocannabinoids at human CB1R, and CB2R in Chinese hamster ovary (CHO) cells stably expressing these receptors and in C57BL/6 mice in an attempt to better understand their pharmacodynamics. Specifically, ∆9-THC, ∆9-tetrahydrocannabinolic acid (∆9-THCa), ∆9-tetrahydrocannabivarin (THCV), CBD, cannabidiolic acid (CBDa), cannabidivarin (CBDV), cannabigerol (CBG), and cannabichromene (CBC) were evaluated. Compounds were assessed for their affinity to receptors, ability to inhibit cAMP accumulation, ßarrestin2 recruitment, receptor selectivity, and ligand bias in cell culture; and cataleptic, hypothermic, anti-nociceptive, hypolocomotive, and anxiolytic effects in mice. Our data reveal partial agonist activity for many phytocannabinoids tested at CB1R and/or CB2R, as well as in vivo responses often associated with activation of CB1R. These data build on the growing body of literature showing cannabinoid receptor-dependent pharmacology for these less-abundant phytocannabinoids and are critical in understanding the complex and interactive pharmacology of Cannabis-derived molecules.

Indomethacin Enhances Type 1 Cannabinoid Receptor Signaling.

In addition to its known actions as a non-selective cyclooxygenase (COX) 1 and 2 inhibitor, we hypothesized that indomethacin can act as an allosteric modulator of the type 1 cannabinoid receptor (CB1R) because of its shared structural features with the known allosteric modulators of CB1R. Indomethacin enhanced the binding of [3H]CP55940 to hCB1R and enhanced AEA-dependent [35S]GTPγS binding to hCB1R in Chinese hamster ovary (CHO) cell membranes. Indomethacin (1 µM) also enhanced CP55940-dependent ßarrestin1 recruitment, cAMP inhibition, ERK1/2 and PLCß3 phosphorylation in HEK293A cells expressing hCB1R, but not in cells expressing hCB2R. Finally, indomethacin enhanced the magnitude and duration of CP55940-induced hypolocomotion, immobility, hypothermia, and anti-nociception in C57BL/6J mice. Together, these data support the hypothesis that indomethacin acted as a positive allosteric modulator of hCB1R. The identification of structural and functional features shared amongst allosteric modulators of CB1R may lead to the development of novel compounds designed for greater CB1R or COX selectivity and compounds designed to modulate both the prostaglandin and endocannabinoid systems.