Allosteric Coupling of Drug Binding and Intracellular Signaling in the A2A Adenosine Receptor.

Signaling across cellular membranes, the 826 human G protein-coupled receptors (GPCRs) govern a wide range of vital physiological processes, making GPCRs prominent drug targets. X-ray crystallography provided GPCR molecular architectures, which also revealed the need for additional structural dynamics data to support drug development. Here, nuclear magnetic resonance (NMR) spectroscopy with the wild-type-like A2A adenosine receptor (A2AAR) in solution provides a comprehensive characterization of signaling-related structural dynamics. All six tryptophan indole and eight glycine backbone 15N-1H NMR signals in A2AAR were individually assigned. These NMR probes provided insight into the role of Asp522.50 as an allosteric link between the orthosteric drug binding site and the intracellular signaling surface, revealing strong interactions with the toggle switch Trp 2466.48, and delineated the structural response to variable efficacy of bound drugs across A2AAR. The present data support GPCR signaling based on dynamic interactions between two semi-independent subdomains connected by an allosteric switch at Asp522.50.

Altering the intestinal microbiota during a critical developmental window has lasting metabolic consequences.

Acquisition of the intestinal microbiota begins at birth, and a stable microbial community develops from a succession of key organisms. Disruption of the microbiota during maturation by low-dose antibiotic exposure can alter host metabolism and adiposity. We now show that low-dose penicillin (LDP), delivered from birth, induces metabolic alterations and affects ileal expression of genes involved in immunity. LDP that is limited to early life transiently perturbs the microbiota, which is sufficient to induce sustained effects on body composition, indicating that microbiota interactions in infancy may be critical determinants of long-term host metabolic effects. In addition, LDP enhances the effect of high-fat diet induced obesity. The growth promotion phenotype is transferrable to germ-free hosts by LDP-selected microbiota, showing that the altered microbiota, not antibiotics per se, play a causal role. These studies characterize important variables in early-life microbe-host metabolic interaction and identify several taxa consistently linked with metabolic alterations. PAPERCLIP:

High sensitivity top-down proteomics captures single muscle cell heterogeneity in large proteoforms.

Single-cell proteomics has emerged as a powerful method to characterize cellular phenotypic heterogeneity and the cell-specific functional networks underlying biological processes. However, significant challenges remain in single-cell proteomics for the analysis of proteoforms arising from genetic mutations, alternative splicing, and post-translational modifications. Herein, we have developed a highly sensitive functionally integrated top-down proteomics method for the comprehensive analysis of proteoforms from single cells. We applied this method to single muscle fibers (SMFs) to resolve their heterogeneous functional and proteomic properties at the single-cell level. Notably, we have detected single-cell heterogeneity in large proteoforms (>200 kDa) from the SMFs. Using SMFs obtained from three functionally distinct muscles, we found fiber-to-fiber heterogeneity among the sarcomeric proteoforms which can be related to the functional heterogeneity. Importantly, we detected multiple isoforms of myosin heavy chain (~223 kDa), a motor protein that drives muscle contraction, with high reproducibility to enable the classification of individual fiber types. This study reveals single muscle cell heterogeneity in large proteoforms and establishes a direct relationship between sarcomeric proteoforms and muscle fiber types, highlighting the potential of top-down proteomics for uncovering the molecular underpinnings of cell-to-cell variation in complex systems.

Online Mixed-Bed Ion Exchange Chromatography for Native Top-Down Proteomics of Complex Mixtures.

Native top-down mass spectrometry (nTDMS) allows characterization of protein structure and noncovalent interactions with simultaneous sequence mapping and proteoform characterization. The majority of nTDMS studies utilize purified recombinant proteins, with significant challenges hindering application to endogenous systems. To perform native top-down proteomics (nTDP), where endogenous proteins from complex biological systems are analyzed by nTDMS, it is essential to separate proteins under nondenaturing conditions. However, it remains difficult to achieve high resolution with MS-compatible online chromatography while preserving protein tertiary structure and noncovalent interactions. Herein, we report the use of online mixed-bed ion exchange chromatography (IEC) to enable separation of endogenous proteins from complex mixtures under nondenaturing conditions, preserving noncovalent interactions for nTDP analysis. We have successfully detected large proteins (>146 kDa) and identified endogenous metal-binding and oligomeric protein complexes in human heart tissue lysate. The use of a mixed-bed stationary phase allowed retention and elution of proteins over a wide range of isoelectric points without altering the sample or mobile phase pH. Overall, our method provides a simple online IEC-MS platform that can effectively separate proteins from complex mixtures under nondenaturing conditions and preserve higher-order structure for nTDP applications.

Extrahelical Binding Site for a 1H-Imidazo[4,5-c]quinolin-4-amine A3 Adenosine Receptor Positive Allosteric Modulator on Helix 8 and Distal Portions of Transmembrane Domains 1 and 7.

This study describes the localization and computational prediction of a binding site for the A3 adenosine receptor (A3AR) positive allosteric modulator 2-cyclohexyl-1H-imidazo[4,5-c]quinolin-4-(3,4-dichlorophenyl)amine (LUF6000). The work reveals an extrahelical lipid-facing binding pocket disparate from the orthosteric binding site that encompasses transmembrane domain (TMD) 1, TMD7, and Helix (H) 8, which was predicted by molecular modeling and validated by mutagenesis. According to the model, the nearly planar 1H-imidazo[4,5-c]quinolinamine ring system lies parallel to the transmembrane segments, inserted into an aromatic cage formed by π-π stacking interactions with the side chains of Y2847.55 in TMD7 and Y2938.54 in H8 and by π-NH bonding between Y2847.55 and the exocyclic amine. The 2-cyclohexyl group is positioned "upward" within a small hydrophobic subpocket created by residues in TMDs 1 and 7, while the 3,4-dichlorophenyl group extends toward the lipid interface. An H-bond between the N-1 amine of the heterocycle and the carbonyl of G291.49 further stabilizes the interaction. Molecular dynamics simulations predicted two metastable intermediates, one resembling a pose determined by molecular docking and a second involving transient interactions with Y2938.54; in simulations, each of these intermediates converges into the final bound state. Structure-activity-relationships for replacement of either of the identified exocyclic or endocyclic amines with heteroatoms lacking H-bond donating ability were consistent with the hypothetical pose. Thus, we characterized an allosteric pocket for 1H-imidazo[4,5-c]quinolin-4-amines that is consistent with data generated by orthogonal methods, which will aid in the rational design of improved A3AR positive allosteric modulators. SIGNIFICANCE STATEMENT: Orthosteric A3AR agonists have advanced in clinical trials for inflammatory conditions, liver diseases, and cancer. Thus, the clinical appeal of selective receptor activation could extend to allosteric enhancers, which would induce site- and time-specific activation in the affected tissue. By identifying the allosteric site for known positive allosteric modulators, structure-based drug discovery modalities can be enabled to enhance the pharmacological properties of the 1H-imidazo[4,5-c]quinolin-4-amine class of A3AR positive allosteric modulators.

Comprehensive Metabolomic Analysis of Human Heart Tissue Enabled by Parallel Metabolite Extraction and High-Resolution Mass Spectrometry.

The heart contracts incessantly and requires a constant supply of energy, utilizing numerous metabolic substrates, such as fatty acids, carbohydrates, lipids, and amino acids, to supply its high energy demands. Therefore, a comprehensive analysis of various metabolites is urgently needed for understanding cardiac metabolism; however, complete metabolome analyses remain challenging due to the broad range of metabolite polarities, which makes extraction and detection difficult. Herein, we implemented parallel metabolite extractions and high-resolution mass spectrometry (MS)-based methods to obtain a comprehensive analysis of the human heart metabolome. To capture the diverse range of metabolite polarities, we first performed six parallel liquid-liquid extractions (three monophasic, two biphasic, and one triphasic) of healthy human donor heart tissue. Next, we utilized two complementary MS platforms for metabolite detection: direct-infusion ultrahigh-resolution Fourier-transform ion cyclotron resonance (DI-FTICR) and high-resolution liquid chromatography quadrupole time-of-flight tandem MS (LC-Q-TOF-MS/MS). Using DI-FTICR MS, 9644 metabolic features were detected where 7156 were assigned a molecular formula and 1107 were annotated by accurate mass assignment. Using LC-Q-TOF-MS/MS, 21,428 metabolic features were detected where 285 metabolites were identified based on fragmentation matching against publicly available libraries. Collectively, 1340 heart metabolites were identified in this study, which span a wide range of polarities including polar (benzenoids, carbohydrates, and nucleosides) as well as nonpolar (phosphatidylcholines, acylcarnitines, and fatty acids) compounds. The results from this study will provide critical knowledge regarding the selection of appropriate extraction and MS detection methods for the analysis of the diverse classes of human heart metabolites.

Small-Scale Serial Size Exclusion Chromatography (s3SEC) for High Sensitivity Top-Down Proteomics of Large Proteoforms.

Top-down-mass spectrometry (MS)-based proteomics has emerged as a premier technology to examine proteins at the proteoform level, enabling characterization of genetic mutations, alternative splicing, and post-translational modifications. However, significant challenges that remain in top-down proteomics include the analysis of large proteoforms and the sensitivity required to examine proteoforms from minimal amounts of sample. To address these challenges, we have developed a new method termed "small-scale serial Size Exclusion Chromatography" (s3SEC), which incorporates a small-scale protein extraction (1 mg of tissue) and serial SEC without postfractionation sample handling, coupled with online high sensitivity capillary reversed-phase liquid chromatography tandem MS (RPLC-MS/MS) for analysis of large proteoforms. The s3SEC-RPLC-MS/MS method significantly enhanced the sensitivity and reduced the proteome complexity across the fractions, enabling the detection of high MW proteoforms previously undetected in one-dimensional (1D)-RPLC analysis. Importantly, we observed a drastic improvement in the signal intensity of high MW proteoforms in early fractions when using the s3SEC-RPLC method. Moreover, we demonstrate that this s3SEC-RPLC-MS/MS method also allows the analysis of lower MW proteoforms in subsequent fractions without significant alteration in proteoform abundance and equivalent or improved fragmentation efficiency to that of the 1D-RPLC approach. Although this study focuses on the use of cardiac tissue, the s3SEC-RPLC-MS/MS method could be broadly applicable to other systems with limited sample inputs.

The prevalence of Human Immunodeficiency Virus infection among voluntary blood donors in mainland China: A systematic review and meta-analysis.

Human immunodeficiency virus (HIV) infection through transfusion has been an imperative challenge for blood safety. Despite the implementation of screening strategies, there was still the residual risk of transfusion-transmitted HIV. Considering that the prevalence of HIV infection in blood donors is significant for evaluating blood safety and potential risks to the population, meta-analysis was applied to investigate the HIV prevalence among voluntary blood donors during the past 27 years to characterize the epidemiology and related risk factors of HIV in blood donors. The literature concerning the HIV screening reactive rate and prevalence in Chinese voluntary blood donors was collected through the systematic searching of four electronic databases. After integrating data, following the Preferred Reporting of Items for Systematic Reviews and Meta-Analyses guidelines, data manipulation and statistical analyses were conducted by Stata 12.0. The results indicated that overall HIV prevalence was 0.0178% (95% confidence interval [CI], 0.0169%-0.0187%) with a remarkable rise, which varied from 2000 (0.0034%) to 2015 (0.027%). The HIV window period infection rate was 0.0475‱ (95% CI, 0.0304‱-0.0646‱). Importantly, subgroup analysis revealed the heterogeneity in gender, occupations, education and donation frequency. With the effective control of HIV transmission through blood, HIV prevalence declined in China to some extent in recent years, and the characteristics of HIV epidemic in some provinces have drastically changed. However, remaining relatively high HIV prevalence and overall increased trend of HIV prevalence since the 21th century demonstrates the potential residual risk of blood transfusion, and the whole society is supposed to pay close attention to HIV infection.

A2B adenosine receptor signaling and regulation.

The A2B adenosine receptor (A2BR) is one of the four adenosine-activated G protein-coupled receptors. In addition to adenosine, protein kinase C (PKC) was recently found to activate the A2BR. The A2BR is coupled to both Gs and Gi, as well as Gq proteins in some cell types. Many primary cells and cell lines, such as bladder and breast cancer, bronchial smooth muscle, skeletal muscle, and fat cells, express the A2BR endogenously at high levels, suggesting its potentially important role in asthma, cancer, diabetes, and other conditions. The A2BR has been characterized as both pro- and anti-inflammatory, inducing cell type-dependent secretion of IL-6, IL-8, and IL-10. Theophylline and enprofylline have long been used for asthma treatment, although it is still not entirely clear if their A2BR antagonism contributes to their therapeutic effects or side effects. The A2BR is required in ischemic cardiac preconditioning by adenosine. Both A2BR and protein kinase C (PKC) contribute to cardioprotection, and both modes of A2BR signaling can be blocked by A2BR antagonists. Inhibitors of PKC and A2BR are in clinical cancer trials. Sulforaphane and other isothiocyanates from cruciferous vegetables such as broccoli and cauliflower have been reported to inhibit A2BR signaling via reaction with an intracellular A2BR cysteine residue (C210). A full, A2BR-selective agonist, critical to elucidate many controversial roles of the A2BR, is still not available, although agonist-bound A2BR structures have recently been reported.

Machine learning-aided search for ligands of P2Y6 and other P2Y receptors.

The P2Y6 receptor, activated by uridine diphosphate (UDP), is a target for antagonists in inflammatory, neurodegenerative, and metabolic disorders, yet few potent and selective antagonists are known to date. This prompted us to use machine learning as a novel approach to aid ligand discovery, with pharmacological evaluation at three P2YR subtypes: initially P2Y6 and subsequently P2Y1 and P2Y14. Relying on extensive published data for P2Y6R agonists, we generated and validated an array of classification machine learning model using the algorithms deep learning (DL), adaboost classifier (ada), Bernoulli NB (bnb), k-nearest neighbors (kNN) classifier, logistic regression (lreg), random forest classifier (rf), support vector classification (SVC), and XGBoost (XGB) classifier models, and the common consensus was applied to molecular selection of 21 diverse structures. Compounds were screened using human P2Y6R-induced functional calcium transients in transfected 1321N1 astrocytoma cells and fluorescent binding inhibition at closely related hP2Y14R expressed in CHO cells. The hit compound ABBV-744, an experimental anticancer drug with a 6-methyl-7-oxo-6,7-dihydro-1H-pyrrolo[2,3-c]pyridine scaffold, had multifaceted interactions with the P2YR family: hP2Y6R inhibition in a non-surmountable fashion, suggesting that noncompetitive antagonism, and hP2Y1R enhancement, but not hP2Y14R binding inhibition. Other machine learning-selected compounds were either weak (experimental anti-asthmatic drug AZD5423 with a phenyl-1H-indazole scaffold) or inactive in inhibiting the hP2Y6R. Experimental drugs TAK-593 and GSK1070916 (100 µM) inhibited P2Y14R fluorescent binding by 50% and 38%, respectively, and all other compounds by < 20%. Thus, machine learning has led the way toward revealing previously unknown modulators of several P2YR subtypes that have varied effects.

Genetic and functional modulation by agonist MRS5698 and allosteric enhancer LUF6000 at the native A3 adenosine receptor in HL-60 cells.

The A3 adenosine receptor (AR) is an important inflammatory and immunological target. However, the underlying mechanisms are not fully understood. Here, we report the gene regulation in HL-60 cells treated acutely with highly selective A3AR agonist MRS5698, positive allosteric modulator (PAM) LUF6000, or both. Both pro- and anti-inflammatory genes, such as IL-1a, IL-1ß, and NFκBIZ, are significantly upregulated. During our observations, LUF6000 alone produced a lesser effect, while the MRS5698 + LUF6000 group demonstrated generally greater effects than MRS5698 alone, consistent with allosteric enhancement. The number of genes up- and down-regulated are similar. Pathway analysis highlighted the critical involvement of signaling molecules, including IL-6 and IL-17. Important upstream regulators include IL-1a, IL-1ß, TNF-α, NF-κB, etc. PPAR, which modulates eicosanoid metabolism, was highly downregulated by the A3AR agonist. Considering previous pharmacological results and mathematical modeling, LUF6000's small enhancement of genetic upregulation suggested that MRS5698 is a nearly full agonist, which we demonstrated in both cAMP and calcium assays. The smaller effect of LUF6000 on MRS5698 in comparison to its effect on Cl-IB-MECA was shown in both HL-60 cells endogenously expressing the human (h) A3AR and in recombinant hA3AR-expressing CHO cells, consistent with its HL-60 cell genetic regulation patterns. In summary, by using both selective agonists and PAM, we identified genes that are closely relevant to immunity and inflammation to be regulated by A3AR in differentiated HL-60 cells, a cell model of neutrophil function. In addition, we demonstrated the previously uncharacterized allosteric signaling-enhancing effect of LUF6000 in cells endogenously expressing the hA3AR.

Functional characterization of growth hormone releasing hormone and its receptor in amphioxus with implication for origin of hypothalamic-pituitary axis.

Growth hormone-releasing hormone (GHRH) has been widely shown to stimulate growth hormone (GH) production via binding to GHRH receptor GHRHR in various species of vertebrates, but information regarding the functional roles of GHRH and GHRHR in the protochordate amphioxus remains rather scarce. We showed here that two mature peptides, BjGHRH-1 and BjGHRH-2, encoded by BjGHRH precursor, and a single BjGHRHR protein were identified in the amphioxus Branchiostoma. japonicum. Like the distribution profiles of vertebrate GHRHs and GHRHRs, both the genes Bjghrh and Bjghrhr were widely expressed in the different tissues of amphioxus, including in the cerebral vesicle, Hatschek's pit, neural tube, gill, hepatic caecum, notochord, testis and ovary. Moreover, both BjGHRH-1 and BjGHRH-2 interacted with BjGHRHR, and triggered the cAMP/PKA signal pathway in a dose-dependent manner. Importantly, BjGHRH-1 and BjGHRH-2 were both able to activate the expression of GH-like gene in the cells of Hatschek's pit. These indicate that a functional vertebrate-like GHRH-GHRHR axis had already emerged in amphioxus, which is a seminal innovation making physiological divergence including reproduction, growth, metabolism, stress and osmoregulation possible during the early evolution of vertebrates.

Global air pollution exposure and congenital anomalies: an updated systematic review and meta-analysis of epidemiological studies.

A systematic review and meta-analysis was conducted to evaluate recent epidemiological evidence on the association of air pollution with congenital anomalies (CAs). Of 11,014 records, 49 were finally included in this meta-analysis. Per 10 µg/m3 increase in air pollutant, PM10 exposure during the 1st month of pregnancy and at the first trimester (T1) was associated with increased overall CAs. Further, exposure to PM10 was associated with congenital heart disease (OR = 1.055, 95% CI: 1.035, 1.074) and patent ductus arteriosus (OR = 1.094, 95% CI: 1.020, 1.168) at T1, with chromosomal anomalies during the entire pregnancy and with nervous system anomalies when exposure occurred 3 months prior to pregnancy, during the 1st, 2nd months of pregnancy and at T1. Besides, a significant association with overall CAs was observed for a combined exposure of PM10 and SO2 during the 1st month of gestation (OR: 1.101, 95% CI: 1.023, 1.180). A combined exposure of PM10 and CO was also associated with tetralogy of Fallot during 3-8 weeks of gestation (OR: 1.016, 95% CI: 1.005, 1.027). No significant associations were observed between PM2.5, NO2, and O3 exposure and CAs.

The association between retinol-binding protein 4 and risk of type 2 diabetes: A systematic review and meta-analysis.

Retinol-binding protein 4 (RBP4) was controversially associated with type 2 diabetes mellitus (T2DM). This meta-analysis aimed at evaluating the association between RBP4 level and T2DM risk. MEDLINE and EMBASE were searched to identify relevant studies up to 3 December 2022. Random effects model was used to pool multivariate-adjusted odds ratios (ORs) and 95% confidence intervals (CIs). Publication bias was estimated by Funnel plot and Egger's test, it was considered to be significant when P < 0.05. Eight studies including 8087 participants were finally included. Compared to those with the lowest level, subjects with the highest level of RBP4 have a higher risk of T2DM (OR = 1.47, 95% CI: 1.16-1.78, P < 0.001, I2 = 86.9%). No publication bias among the included studies was found (t = 0.94, P = 0.377). This meta-analysis indicated that high RBP4 level was associated with increasing risk of T2DM.

One Stone, Two Birds: A Peptide-Au(I) Infinite Coordination Supermolecule for the Confederate Physical and Biological Radiosensitization in Cancer Radiation Therapy.

Over half of cancer patients are subjected to radiotherapy, but owing to the deficient amount of reactive oxygen radicals (ROS) and DNA double-strand breaks (DSBs), a fair number of them suffer from radiotherapy resistance and the subsequent short-term survival opportunity. To overcome it, many successes have been achieved in radiosensitizer discovery using physical strategy and/or biological strategy, but significant challenges remain regarding developing clinically translational radiosensitizers. Herein, a peptide-Au(I) infinite coordination supermolecule termed PAICS is developed that combined both physical and biological radiosensitization and possessed pharmaceutical characteristics including adequate circulatory stability, controllable drug release, tumor-prioritized accumulation, and the favorable body eliminability. As expected, monovalent gold ion endowed this supermolecule with high X-ray absorption and the subsequent radiosensitization. Furthermore, a peptide targeting CRM1, is assembled into the supermolecule, which successfully activates p53 and apoptosis pathway, thereby further sensitizing radiotherapy. As a result, PAICS showed superior ability for radiotherapy sensitization in vivo and maintained a favorable safety profile. Thus, the PAICS reported here will offer a feasible solution to simultaneously overcome both the pharmaceutical obstacles of physical and biological radiosensitizers and will enable the development of a class of nanomedicines for tumor radiotherapy sensitization.

Highly stretchable organic electrochemical transistors with strain-resistant performance.

Realizing fully stretchable electronic materials is central to advancing new types of mechanically agile and skin-integrable optoelectronic device technologies. Here we demonstrate a materials design concept combining an organic semiconductor film with a honeycomb porous structure with biaxially prestretched platform that enables high-performance organic electrochemical transistors with a charge transport stability over 30-140% tensional strain, limited only by metal contact fatigue. The prestretched honeycomb semiconductor channel of donor-acceptor polymer poly(2,5-bis(2-octyldodecyl)-3,6-di(thiophen-2-yl)-2,5-diketo-pyrrolopyrrole-alt-2,5-bis(3-triethyleneglycoloxy-thiophen-2-yl) exhibits high ion uptake and completely stable electrochemical and mechanical properties over 1,500 redox cycles with 104 stretching cycles under 30% strain. Invariant electrocardiogram recording cycles and synapse responses under varying strains, along with mechanical finite element analysis, underscore that the present stretchable organic electrochemical transistor design strategy is suitable for diverse applications requiring stable signal output under deformation with low power dissipation and mechanical robustness.

Intranasal administration of Acinetobacter lwoffii in a murine model of asthma induces IL-6-mediated protection associated with cecal microbiota changes.

BACKGROUND: Early-life exposure to certain environmental bacteria including Acinetobacter lwoffii (AL) has been implicated in protection from chronic inflammatory diseases including asthma later in life. However, the underlying mechanisms at the immune-microbe interface remain largely unknown. METHODS: The effects of repeated intranasal AL exposure on local and systemic innate immune responses were investigated in wild-type and Il6-/- , Il10-/- , and Il17-/- mice exposed to ovalbumin-induced allergic airway inflammation. Those investigations were expanded by microbiome analyses. To assess for AL-associated changes in gene expression, the picture arising from animal data was supplemented by in vitro experiments of macrophage and T-cell responses, yielding expression and epigenetic data. RESULTS: The asthma preventive effect of AL was confirmed in the lung. Repeated intranasal AL administration triggered a proinflammatory immune response particularly characterized by elevated levels of IL-6, and consequently, IL-6 induced IL-10 production in CD4+ T-cells. Both IL-6 and IL-10, but not IL-17, were required for asthma protection. AL had a profound impact on the gene regulatory landscape of CD4+ T-cells which could be largely recapitulated by recombinant IL-6. AL administration also induced marked changes in the gastrointestinal microbiome but not in the lung microbiome. By comparing the effects on the microbiota according to mouse genotype and AL-treatment status, we have identified microbial taxa that were associated with either disease protection or activity. CONCLUSION: These experiments provide a novel mechanism of Acinetobacter lwoffii-induced asthma protection operating through IL-6-mediated epigenetic activation of IL-10 production and with associated effects on the intestinal microbiome.

Species dependence of A3 adenosine receptor pharmacology and function.

Efforts to fully understand pharmacological differences between G protein-coupled receptor (GPCR) species homologues are generally not pursued in detail during the drug development process. To date, many GPCRs that have been successfully targeted are relatively well-conserved across species in amino acid sequence and display minimal variability of biological effects. However, the A3 adenosine receptor (AR), an exciting drug target for a multitude of diseases associated with tissue injury, ischemia, and inflammation, displays as little as 70% sequence identity among mammalian species (e.g., rodent vs. primate) commonly used in drug development. Consequently, the pharmacological properties of synthetic A3AR ligands vary widely, not only in binding affinity, selectivity, and signaling efficacy, but to the extent that some function as agonists in some species and antagonists in others. Numerous heterocyclic antagonists that have nM affinity at the human A3AR are inactive or weakly active at the rat and mouse A3ARs. Positive allosteric modulators, including the imidazo [4,5-c]quinolin-4-amine derivative LUF6000, are only active at human and some larger animal species that have been evaluated (rabbit and dog), but not rodents. A3AR agonists evoke systemic degranulation of rodent, but not human mast cells. The rat A3AR undergoes desensitization faster than the human A3AR, but the human homologue can be completely re-sensitized and recycled back to the cell surface. Thus, comprehensive pharmacological evaluation and awareness of potential A3AR species differences are critical in studies to further understand the basic biological functions of this unique AR subtype. Recombinant A3ARs from eight different species have been pharmacologically characterized thus far. In this review, we describe in detail current knowledge of species differences in genetic identity, G protein-coupling, receptor regulation, and both orthosteric and allosteric A3AR pharmacology.

Fluorescent A2A and A3 adenosine receptor antagonists as flow cytometry probes.

Adenosine receptor (AR) ligands are being developed for metabolic, cardiovascular, neurological, and inflammatory diseases and cancer. The ease of drug discovery is contingent on the availability of pharmacological tools. Fluorescent antagonist ligands for the human A2A and A3ARs were synthesized using two validated pharmacophores, 1,3-dipropyl-8-phenylxanthine and triazolo[1,5-c]quinazolin-5-yl)amine, which were coupled to eight reporter fluorophores: AlexaFluor, JaneliaFluor (JF), cyanine, and near infrared (NIR) dyes. The conjugates were first screened using radioligand binding in HEK293 cells expressing one of the three AR subtypes. The highest affinities at A2AAR were Ki 144-316 nM for 10, 12, and 19, and at A3AR affinity of Ki 21.6 nM for 19. Specific binding of JF646 conjugate MRS7774 12 to the HEK293 cell surface A2AAR was imaged using confocal microscopy. Compound 19 MRS7535, a triazolo[1,5-c]quinazolin-5-yl)amine containing a Sulfo-Cy7 NIR dye, was suitable for A3AR characterization in whole cells by flow cytometry (Kd 11.8 nM), and its bitopic interaction mode with an A3AR homology model was predicted. Given its affinity and selectivity (11-fold vs. A2AAR, ~ 50-fold vs. A1AR and A2BAR) and a good specific-to-nonspecific binding ratio, 19 could be useful for live cell or potentially a diagnostic in vivo NIR imaging tool and/or therapy targeting the A3AR.

Ambient fine particulate matter and pregnancy outcomes: An umbrella review.

The available evidence on the effects of ambient fine particulate matter (PM2.5) and pregnancy outcomes (birth outcomes and pregnancy complications) has increased substantially. The purpose of this umbrella review is to refine the evidence of the association between birth outcome (birth defects) and PM2.5; and summarize the credibility of existing research on the association between pregnancy complications and PM2.5. We searched PubMed, Web of Science, Embase, and Cochrane databases for relevant systematic reviews and meta-analyses up to March 16, 2022 in accordance with PRISMA guidelines. Two independent investigators conducted data extraction. AMSTAR 2 and GRADE assessment criteria were used to evaluate the methodological and evidence quality. We performed subgroup analyses by trimesters of pregnancy. The review protocol for this study has been registered in PROSPERO (CRD42022325550). This umbrella review identified a total of 41 systematic reviews, including 28 articles evaluating the influence of PM2.5 on birth outcomes and 13 on pregnancy complications. Positive associations between perinatal PM2.5 exposure and adverse birth outcomes were found, including low birth weight, preterm birth, stillbirth, small for gestational age, and birth defects. Pregnant women exposed to PM2.5 had a significantly higher risk of developing hypertensive disorder of pregnancy, gestational diabetes mellitus, gestational hypertension, and preeclampsia. The findings of subgroup analysis demonstrated that the effects of ambient PM2.5 exposure on pregnancy outcomes varied by trimesters. The findings of this extensive umbrella review provide convincing proof that exposure to ambient PM2.5 raises the risks of unfavorable birth outcomes and pregnancy complications. Some associations show considerable disparity between trimesters. These findings have implications for strengthen perinatal health care on air pollution and improving intergenerational equity.