Binding of ¹²⁵I-labeled MIP-1α, MIP-1β, and RANTES to CCR5 is measured essentially using intact HEK-293 cells stably expressing the receptor or membrane preparations thereof. Briefly, cells are resuspended in binding buffer (50 mM HEPES containing 1 mM CaCl₂, 5 mM MgCl₂, and 0.5% bovine serum albumin [BSA] and adjusted to pH 7.4) to a density of 2×10⁶ cells/mL. For membrane preparations, phosphate-buffered saline (PBS)-washed cells are resuspended in lysis buffer (20 mM HEPES, 1 mM CaCl₂, 1 tablet COMPLETE per 50 mL, pH 7.4; Boehringer) prior to homogenization in a Polytron hand-held homogenizer, ultracentrifugation (40,000× g for 30 min), and resuspension in binding buffer to a protein concentration of 0.25 mg/mL (12.5 μg of membrane protein is used in each well of a 96-well plate). ¹²⁵I-radiolabeled MIP-1α, MIP-1β, and RANTES are prepared and diluted in binding buffer to a final concentration of 400 pM in the assay. Appropriate maraviroc dilutions are added to each well to a final volume of 100 μL, the assay plates incubated for 1 h, and the contents filtered through preblocked and washed Unifilter plates which are counted following overnight drying^[1].

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

HEK-293 cell aliquots (100 μL at 1×10⁶ cells/mL) are plated into poly-D-lysine-coated plates and incubated at 37°C overnight. A 1:1 mix of soluble recombinant human CD4 (sCD4) (diluted to 4.5 nM in culture medium) and HIV-1 gp120 is incubated at room temperature for 15 min prior to its addition to PBS-washed cells in the presence of dilutions of maraviroc to enable IC₅₀ determination. The assay plates are incubated at 37°C for 1 h and washed. Eu³⁺-labeled anti-gp120 antibody (1/500 dilution in assay buffer) is added to each well (50 μL) and incubated for 1 h. The plate is washed three times with wash buffer prior to the addition of enhancement solution (200 μL/well) and measurement of Eu³⁺ fluorescence (Victor²multilabel counter; “Europium” protocol). Nonspecific binding is taken as the fluorescence measured for gp120 incubated with cells in the absence of preincubation with sCD4^[1].

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

Rats and Dogs^[1]
Preclinical pharmacokinetic studies are carried out with maraviroc following a single intravenous and oral administration to both male Sprague-Dawley rats (1 mg/kg of body weight given intravenously [i.v.] and 10 mg/kg given orally [p.o.]; n=2) and male beagle dogs (0.5 mg/kg i.v. and 2 mg/kg p.o; n=4). Plasma samples are taken for up to 24 h postdose, and the concentrations of unchanged maraviroc are determined using a specific high-performance liquid chromatography-tandem mass spectrum assay.
Mice^[2]
Splenocytes are collected from 6-10 week old CCR5^-/- mice or wild-type controlmice (n=8 per group) and naive CD4⁺ CD45RB^high T-cells are isolated by cell sorting. A total of 3×10⁵ CD45RB^high cells are then injected intravenously into Rag1^-/- mice that are subsequently weighed and assessed for fecal score every 20 days to evaluate IBD development. To investigate whether Maraviroc rescues from intestinal inflammation induced by transfer colitis, Rag1^-/- mice are injected with CD4⁺ CD45RB^-/- T-cells and 34 days later randomized into either a control group (no further treatment, n=6) or treatment with Maraviroc, 50 mg/kg/d Maraviroc per os (n=4) for 3 weeks, 5 d/week.

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

• [1]. Dorr P, et al. Maraviroc (UK-427,857), a potent, orally bioavailable, and selective small-molecule inhibitor of chemokine receptor CCR5 with broad-spectrum anti-human immunodeficiency virus type 1 activity. Antimicrob Agents Chemother. 2005 Nov;49(11):472  [Content Brief]

  [2]. Mencarelli A, et al. Highly specific blockade of CCR5 inhibits leukocyte trafficking and reduces mucosal inflammation in murine colitis. Sci Rep. 2016 Aug 5;6:30802.  [Content Brief]

  [3]. Romero-Sánchez MC, et al. Effect of maraviroc on HIV-disease progression-related biomarkers. Antimicrob Agents Chemother. 2012 Nov;56(11):5858-64.  [Content Brief]

  [4]. Huilin Mou, et al. NRSF and CCR5 Established Neuron-glia Communication during Acute and Chronic Stresses. Journal of Drug Metabolism & Toxicology. January 10, 2016.