A cDNA encoding a multispecific organic anion transporter 3 (hOAT3) was isolated from a human kidney cDNA library. The hOAT3 cDNA consisted of 2179 base pairs that encoded a 543-amino-acid residue protein with 12 putative transmembrane domains. The deduced amino acid sequence of hOAT3 showed 36 to 51% identity to those of other members of the OAT family. Northern blot analysis revealed that hOAT3 mRNA is expressed in the kidney, brain, and skeletal muscle. When expressed in Xenopus laevis oocytes, hOAT3 mediated the transport of estrone sulfate (K(m) = 3.1 microM), p-aminohippurate (K(m) = 87.2 microM), methotrexate (K(m) = 10.9 microM), and cimetidine (K(m) = 57.4 microM) in a sodium-independent manner. hOAT3 also mediated the transport of dehydroepiandrosterone sulfate, ochratoxin A, PGE(2), estradiol glucuronide, taurocholate, glutarate, cAMP and uric acid. Estrone sulfate did not show any trans-stimulatory effects on either influx or efflux of [(3)H]estrone sulfate via hOAT3. hOAT3 interacted with chemically heterogeneous anionic compounds, such as nonsteroidal anti-inflammatory drugs, diuretics, sulfobromophthalein, penicillin G, bile salts and tetraethyl ammonium bromide. The hOAT3 protein was shown to be localized in the basolateral membrane of renal proximal tubules and the hOAT3 gene was determined to be located on the human chromosome 11q12-q13.3 by fluorescent in situ hybridization analysis. These results suggest an important role of hOAT3 in the excretion/detoxification of endogenous and exogenous organic anions in the kidney.

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Results: We found KM3065-mediated antibody-dependent cellular cytotoxicity was increased 10 to 100-fold compared with rituximab for each of the 20 donors. In contrast to rituximab, KM3065 antibody-dependent cellular cytotoxicity enhancement was similar for both FCGR3A alleles and thus independent of genotype. In addition, antibody-dependent cellular cytotoxicity of both KM3065 and rituximab requires natural killer cells but not monocytes nor polymorphonuclear cells. The antibody-dependent cellular cytotoxicity (ADCC) of each of the 20 donors correlated with the natural killer cell numbers present in the PBMCs. Importantly, using KM3065, the ADCC mediated by effector cells bearing the lower affinity variant Fc␥RIIIa-158F was significantly increased compared with rituximab-mediated ADCC using effector cells bearing the higher affinity Fc␥RIIIa-158V receptors.Conclusions: The use of low-fucose antibodies might improve the therapeutic effects of anti-CD20 therapy for all patients independent of Fc␥RIIIa phenotype beyond that currently seen with even the most responsive patients.

Purpose: Recent studies have revealed that fucose removal from the oligosaccharides of human IgG1 antibodies results in a significant enhancement of antibody-dependent cellular cytotoxicity (ADCC) via improved IgG1 binding to Fc;RIIIa. In this report, we investigated the relationship between enhanced ADCC and antigen density on target cells using IgG1 antibodies with reduced fucose.Experimental Design: Using EL4 cell-derived transfectants with differential expression levels of exogenous human CC chemokine receptor 4 or human CD20 as target cells, ADCC of fucose variants of chimeric IgG1 antibodies specific for these antigens were measured. We further investigated IgG1 binding to natural killer (NK) cells and NK cell activation during ADCC induction to elucidate the mechanism by which low-fucose IgG1 induces ADCC upon target cells with low antigen expression.Results: Low-fucose IgG1s showed potent ADCC at low antigen densities at which their corresponding highfucose counterparts could not induce measurable ADCC. The quantitative analysis revealed that fucose depletion could reduce the antigen amount on target cells required for constant degrees of ADCC induction by 10-fold for CC chemokine receptor 4 and 3-fold for CD20. IgG1 binding to NK cells was increased by ligating IgG1 with clustered antigen, especially for low-fucose IgG1. Up-regulation of an activation marker, CD69, on NK cells, particularly the CD56 dim subset, in the presence of both the antibody and target cells was much greater for the low-fucose antibodies.Conclusions: Our data showed that fucose removal from IgG1 could reduce the antigen amount required for ADCC induction via efficient recruitment and activation of NK cells.

The organic anion transport system is involved in the tubular excretion and reabsorption of various drugs and substances. The purpose of this study was to characterize the effects of various organic anion transport inhibitors on renal organic anion transport using proximal tubule cells stably expressing human organic anion transporter 2 (hOAT2) and hOAT4. Immunohistochemical analysis revealed that hOAT2 is localized to the basolateral side of the proximal tubule in the kidney. hOAT2 mediated a time-and concentration-dependent increase in prostaglandin F 2␣ (PGF 2␣ ) uptake. The organic anion transport inhibitors used for this study were probenecid, 8-(noradamantan-3-yl)-1,3-dipropylxanthine (KW-3902), betamipron, and cilastatin. Probenecid, but not KW-3902, betamipron, and cilastatin, significantly inhibited hOAT2-mediated PGF 2␣ uptake. In contrast, probenecid, KW-3902, and betamipron, but not cilastatin, inhibited hOAT4-mediated estrone sulfate (ES) uptake. Kinetic analyses revealed that these inhibitions were competitive. The K i value of probenecid for hOAT2 was 766 M, whereas those of probenecid, KW-3902, and betamipron for hOAT4 were 54.9, 20.7, and 502 M, respectively. These results suggest that probenecid, KW-3902, and betamipron could inhibit hOAT4-mediated ES uptake in vitro, whereas probenecid alone could inhibit the hOAT2-mediated PGF 2␣ uptake. Comparing the K i values with the therapeutically relevant concentrations of unbound inhibitors in the plasma, probenecid alone was predicted to inhibit hOAT4-mediated organic anion transport in vivo.Various organic anion transport inhibitors are used experimentally and clinically. Probenecid is a conventional and standard organic anion transport inhibitor experimentally, but it is used as a uricosuric drug clinically. In addition, KW-3902, developed as an adenosine A1 receptor antagonist , was also shown to inhibit organic anion transport in the basolateral membrane of opossum kidney cells derived from the American opossum kidney (Nagai et al., 1999). On the other hand, betamipron and cilastatin are administered in combination with carbapenem antibiotics, panipenem, and imipenem, respectively (Birnbaum et al., 1985;Shiba et al., 1991). Betamipron inhibits the uptake of panipenem and imipenem into proximal tubule cells (Hirouchi et al., 1994). On the other hand, imipenem is degraded by human renal dehydropeptidase-I and therefore must be administered in combination with cilastatin, a dehydropeptidase-I inhibitor, to prevent loss of antimicrobial activity in urine and limit potential nephrotoxicity associated with renal metabolism (Craig, 1997).In our previous study, we elucidated the interaction of human organic anion transporter 1 (hOAT1) and hOAT3 with organic anion transport inhibitors including probenecid, KW-3902, betamipron, and cilastatin (Takeda et al., 2001). Thus, the purpose of this study was to characterize the interaction of hOAT2 and hOAT4 with these organic anion transport inhibitors using cells derived from the second portion of the pr...

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Circulation Journal Official Journal of the Japanese Circulation Society http://www. j-circ.or.jp Methods Study PopulationWe retrospectively enrolled 51 consecutive de novo native coronary artery lesions from 44 angina patients who were treated using a single 2nd-generation DES (Xience Prime, Promus Element, or Nobori) under OCT guidance. Exclusion criteria were as follows: coronary artery bypass graft, post-stent dilatation using 2 balloons (kissing balloon inflation and hugging balloon inflation), in-stent restenosis, uninterpretable OCT image, and inability to cross the lesion with the OCT catheter. This study was approved by the Kawasaki Medical School Internal Review Board. Because of the retrospective study design, written informed consent for the interventional procedures, including OCT imaging, was obtained from the patients. Study ProtocolsCardiac Catheterization and OCT After intravenous heparin (100U/kg) and intracoronary nitroglycerin (200 μg) were urrently, 2nd-generation drug-eluting stents (DES) offer good clinical results, 1-4 yet stent underexpansion is still a concern as a cause of DES failure 5-10 or stent thrombosis. 11 Although the extent of coronary calcification is considered to be a contributing factor in stent underexpansion, previous intravascular ultrasound (IVUS) studies have failed to demonstrate a relationship between stent expansion and coronary calcification. 12-14 We previously reported that optical coherence tomography (OCT) offers better quantitative assessment of coronary calcification than IVUS, because OCT can delineate calcified plaque without artifacts. 15 Therefore, we hypothesized that quantitative assessment of coronary calcification using OCT had the potential to predict stent expansion. Accordingly, the purpose of this study was to investigate whether stent expansion could be predicted by the extent of coronary calcification as assessed by OCT. Impact of Target Lesion CoronaryCalcification on Stent Expansion Background: Stent underexpansion remains a concern as a cause of drug-eluting stent (DES) failure. Although coronary calcification is considered to be a contributing factor in stent underexpansion, previous intravascular ultrasound studies have failed to demonstrate this relationship. We investigated whether stent expansion could be predicted by coronary calcification as assessed by optical coherence tomography (OCT).

The purpose of this study was to investigate the characteristics of ochratoxin A (OTA) transport by multispecific human organic anion transporter 4 (hOAT4) using mouse proximal tubule cells stably transfected with hOAT4 (S(2) hOAT4). Immunohistochemical analysis revealed that hOAT4 protein was localized to the apical side of the proximal tubule. S(2) hOAT4 expressed hOAT4 protein in the apical side as well as basolateral side and the cells were cultured on the plastic dish for experiments. S(2) hOAT4 exhibited a time- and concentration-dependent, and a saturable increase in OTA uptake, with an apparent K(m) value of 22.9+/-2.44 microM. The OTA uptakes were inhibited by several substrates for the OATs. Probenecid, piroxicam, octanoate and citrinin inhibited OTA uptake by hOAT4 in a competitive manner (K(i)=44.4-336.4 microM), with the following order of potency: probenecid > piroxicam > octanoate >citrinin. The efflux of OTA by S(2) hOAT4 was higher than that by mock. Addition of OTA resulted in slight decrease in viability of S(2) hOAT4 compared with mock. These results indicate that hOAT4 mediates the high-affinity transport of OTA on the apical side of the proximal tubule, whereas the transport characteristics of OTA are distinct from those by basolateral OATs.