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β-adrenoceptor (β-AR) agonists are known to antagonize thrombin-induced impairment (TII) of bovine and ovine lung endothelial barrier function. The effects of adrenoceptor agonists and other vasoactive agents on human lung microvascular endothelial cell (HULEC-5a) barrier function upon thrombin exposure have not been studied. Furthermore, it is unknown whether the in vitro effects of adrenoceptor agonists translate to lung protective effects in vivo. We observed that epinephrine, norepinephrine, and phenylephrine enhanced normal and prevented TII of HULEC-5a barrier function. Arginine vasopressin and angiotensin II were ineffective. α1B-, α2A/B-, and β1/2-ARs were detectable in HULEC-5a by RT-PCR. Propranolol but not doxazosin blocked the effects of all adrenoceptor agonists. Phenylephrine stimulated β2-AR-mediated Gαs activation with 13-fold lower potency than epinephrine. The EC50 to inhibit TII of HULEC-5a barrier function was 1.8 ± 1.9 nM for epinephrine and >100 nM for phenylephrine. After hemorrhagic shock and fluid resuscitation in rats, Evans blue extravasation into the lung increased threefold (p < 0.01 vs. sham). Single low-dose (1.8 μg/kg) epinephrine administration at the beginning of resuscitation had no effects on blood pressure and reduced Evans blue extravasation by 60% (p < 0.05 vs. vehicle). Our findings confirm the effects of β-adrenoceptor agonists in HULEC-5a and suggest that low-dose β-adrenoceptor agonist treatment protects lung vascular barrier function after traumatic hemorrhagic shock. [ABSTRACT FROM AUTHOR]

It is unknown whether heteromerization between chemokine (C‐X‐C motif) receptor 4 (CXCR4), atypical chemokine receptor 3 (ACKR3) and α1b‐adrenoceptor (α1b‐AR) influences effects of the CXCR4/ACKR3 agonist chemokine (C‐X‐C motif) ligand 12 (CXCL12) and the noncognate CXCR4 agonist ubiquitin on agonist‐promoted G protein activation. We provide biophysical evidence that both ligands stimulate CXCR4‐mediated Gαi activation. Unlike CXCL12, ubiquitin fails to recruit β‐arrestin. Both ligands differentially modulate the conformation of CXCR4:ACKR3 heterodimers and its propensity to hetero‐trimerize with α1b‐AR. CXCR4:ACKR3 heterodimerization reduces the potency of CXCL12, but not of ubiquitin, to activate Gαi. Ubiquitin enhances phenylephrine‐stimulated α1b‐AR‐promoted Gαq activation from hetero‐oligomers comprising CXCR4. CXCL12 enhances phenylephrine‐stimulated α1b‐AR‐promoted Gαq activation from CXCR4:α1b‐AR heterodimers and reduces phenylephrine‐stimulated α1b‐AR‐promoted Gαq activation from ACKR3 comprising heterodimers and trimers. Our findings suggest heteromer and ligand‐dependent functions of the receptor partners. [ABSTRACT FROM AUTHOR]

Previously, we reported that chemokine (C‐C motif) receptor 2 (CCR2) heteromerizes with α1B‐adrenoceptor (α1B‐AR) in leukocytes, through which α1B‐AR controls CCR2. Whether such heteromers are expressed in human vascular smooth muscle cells (hVSMCs) is unknown. Bioluminescence resonance energy transfer confirmed formation of recombinant CCR2:α1b‐AR heteromers. Proximity ligation assays detected CCR2:α1B‐AR heteromers in hVSMCs and human mesenteric arteries. CCR2:α1B‐AR heteromerization per se enhanced α1B‐AR‐mediated Gαq‐coupling. Chemokine (C‐C motif) ligand 2 (CCL2) binding to CCR2 inhibited Gαq activation via α1B‐AR, cross‐recruited β‐arrestin to and induced internalization of α1B‐AR in recombinant systems and in hVSMCs. Our findings suggest that CCR2 within CCR2:α1B‐AR heteromers biases α1B‐AR signaling and provide a mechanism for previous observations suggesting a role for CCL2/CCR2 in the regulation of cardiovascular function. [ABSTRACT FROM AUTHOR]

Chemokine receptor antagonists are being explored for their therapeutic potential in various disease processes. As the chemokine (C–C motif) receptor 2 (CCR2) antagonist RS504393 is known to compete with ligand binding to α1-adrenoceptors, we tested a panel of 10 CCR antagonists for interactions with α1-adrenoceptors to evaluate potential cardiovascular activities and side-effect profiles. The PRESTO-Tango β-arrestin recruitment assay was utilized to test whether the CCR antagonists interfere with α1b-AR activation upon stimulation with phenylephrine. Pressure myography with isolated rat resistance arteries was employed to assess their effects on phenylephrine-induced vasoconstriction. The following antagonists were tested: CCR1–BX471, BX513, BI639667; CCR2–RS504393, INCB3284; CCR3–SB328437; and CCR4–AZD2098, and C021; CCR5–Maraviroc; CCR10-BI6901. The pan-α1-adrenoceptor antagonist prazosin was used as control. Among the CCR antagonists tested, RS504393, BX513, and C021 inhibited phenylephrine-induced β-arrestin recruitment to α1b-adrenoceptor and phenylephrine-induced vasoconstriction. While RS504393 functioned as a competitive α1-adrenoceptor blocker, BX513 and C021 functioned as noncompetitive α1-adrenoceptor antagonists in both assay systems. Furthermore, RS504393, BX513, and C021 dose-dependently dilated arteries that were fully preconstricted with phenylephrine. Our data suggest that CCR antagonists should be screened for cross-reactivity with α1-adrenoceptors to exclude potential adverse cardiovascular effects when used as anti inflammatory drugs. [ABSTRACT FROM AUTHOR]

Byline: Michael Heesen (1), Brunhilde Bloemeke (2), Ulrich Schade (3), Udo Obertacke (4), Matthias Majetschak (4) Keywords: Lipopolysaccharide CD14 Promoter Gene polymorphism Genotyping Infection Critical illness Sepsis Susceptibility Polytrauma Abstract: Abstract Objective. CD14, expressed on the cell surface of monocytes and hepatic Kupffer cells, interacts with Gram-positive and Gram-negative bacteria. Upon CD14 stimulation, these cells respond with the enhanced release of cytokines involved in the pathophysiology of sepsis. The purpose of this study was to evaluate whether the genotype distribution of the --260 C[right arrow]T promoter polymorphism of the CD14 gene is associated with the development of severe sepsis in trauma patients. Patients and participants. Fifty-eight severely injured blunt trauma patients with an injury severity score of16 or more and without pre-existing chronic diseases. Measurements and results. Genotyping for the single nucleotide exchange polymorphism of the CD14 gene was performed by means of a real-time polymerase chain reaction with fluorescence-labeled hybridization probes. Diagnosis of severe sepsis was based on the criteria of the ACCP/SCCM criteria. Fourteen out of the 58 patients (24.6%) developed a trauma-related severe sepsis. The overall allele frequency was 0.58 for the C allele and 0.42 for the T allele. The genotype distribution (TT 0.19, CT 0.47 and CC 0.35) did not differ significantly from a previously reported control group of healthy blood donors. There was no significant difference of the genotype distribution or allele frequency between trauma patients with severe sepsis and patients with an uncomplicated clinical course. Conclusions. This pilot study suggests that the CD14 --260 polymorphism is not associated with an increased risk of severe sepsis in trauma patients. Author Affiliation: (1) Department of Anesthesia, Academic Medical Center, University of Amsterdam, Meibergdreef 9, Postbus 22660, 1100 DD Amsterdam, The Netherlands (2) Department of Dermatology, University Hospital Aachen, Pauwelsstrasse 30, 52057 Aachen, Germany (3) Klinische Forschergruppe Schock und Multiorganversagen, University Hospital Essen, Hufelandstrasse 55, 45122 Essen, Germany (4) Department of Trauma Surgery University Hospital Mannheim, University Heidelberg, Theodor-Kutzer-Ufer 1--3, 68167 Mannheim, Germany Article History: Received Date: 21/08/2001 Accepted Date: 30/05/2002 Article note: Electronic Publication