Microfluidic Sensing System with a Multichannel Surface Plasmon Resonance Chip: Damage-Free Characterization of Cells by Pattern Recognition.

The development of a versatile sensing strategy for the damage-free characterization of cultured cells is of great importance for both fundamental biological research and industrial applications. Here, we present a pattern-recognition-based cell-sensing approach using a multichannel surface plasmon resonance (SPR) chip. The chip, in which five cysteine derivatives with different structures are immobilized on Au films, is capable of generating five unique SPR sensorgrams for the cell-secreted molecules that are contained in cell culture media. An automatic statistical program was built to acquire kinetic parameters from the SPR sensorgrams and to select optimal parameters as "pattern information" for subsequent multivariate analysis. Our system rapidly (∼10 min) provides the complex information by merely depositing a small amount of cell culture media (∼25 µL) onto the chip, and the amount of information obtained is comparable to that furnished by a combination of conventional laborious biochemical assays. This noninvasive pattern-recognition-based cell-sensing approach could potentially be employed as a versatile tool for characterizing cells.

N6-Methylation Assessment in Escherichia coli 23S rRNA Utilizing a Bulge Loop in an RNA-DNA Hybrid.

We propose a sequence-selective assay of N6-methyl-adenosine (m6A) in RNA without PCR or reverse transcription, by employing a hybridization assay with a DNA probe designed to form a bulge loop at the position of a target modified nucleotide. The m6A in the bulge in the RNA-DNA hybrid was assumed to be sufficiently mobile to be selectively recognized by an anti-m6A antibody with a high affinity. By employing a surface-plasmon-resonance measurement or using a microtiter-plate immunoassay method, a specific m6A in the Escherichia coli 23S rRNA sequence could be detected at the nanomolar level when synthesized and purified oligo-RNA fragments were used for measurement. We have successfully achieved the first selective detection of m6A2030 specifically in 23S rRNA from real samples of E. coli total RNA by using our immunochemical approach.

On-Chip Sequence-Specific Immunochemical Epigenomic Analysis Utilizing Outward-Turned Cytosine in a DNA Bulge with Handheld Surface Plasmon Resonance Equipment.

This paper reports a sequence-specific immunoassay chip for DNA methylation assessment by microfluidic-based surface plasmon resonance (SPR) detection. This was achieved by utilizing an affinity measurement involving the target, (methyl)cytosine, in a single-base bulge region and an anti-methylcytosine antibody in a microchannel, following hybridization with a biotinylated bulge-inducing DNA probe. The probe alters the target cytosine in a looped-out state because of the π-π stacking between flanking bases of the target. The probe design is simple and consists of the elimination of guanine paired with the target cytosine from a fragmented full-match sequence. We obtained the single methylation status in 6 amol (48 fg) of synthesized oligo DNA in 45 min, which is the fastest DNA methylation assessment yet reported, without employing a conventional bisulfite reaction, PCR, or sequencing. We also succeeded in discrimination of the methylation status of single cytosine in genomic λ DNA and HCT116 human colon cancer cells. The advantages of the proposed method are its small equipment, simple microfluidics design, ease of handling (two injections of DNA and antibody), lack of need for a methylation-sensitive enzyme, and neutral buffer conditions.

Cytochrome P450 modified polycrystalline indium tin oxide film as a drug metabolizing electrochemical biosensor with a simple configuration.

The development of a biocatalytic electrode consisting of cytochrome P450 (CYP) proteins would be a key technology with which to establish simple drug metabolizing biosensors or screening devices for drug inhibitors. We have successfully detected the direct electron transfer (DET) from a human CYP layer or a CYP microsome adsorbed on a bare indium tin oxide (ITO) film electrode without any modification layers and applied it to drug metabolism evaluation. We compared the electrocatalytic properties of the two ITO films with different surface nanostructures (polycrystalline or amorphous). CYP on polycrystalline ITO film enhanced the electron transfer rate of oxygen reduction about fifteen times more than with amorphous film. The polycrystalline ITO film was a suitable electrode for the adsorption of CYP proteins while maintaining efficient DET and enzymatic activity, probably because of its larger surface area and negatively charged surface. The oxygen reduction current at the polycrystalline ITO film electrodes had increased 3- to 4-fold, specifically coupled with the oxidation of drugs (testosterone and quinidine) by the monooxygenase activity of CYP. In contrast, the oxygen reduction current completely disappeared in the presence of the CYP inhibitor (ketoconazole). Similar results could be obtained from the CYP microsome with sufficiently clear responses. These results indicate that the CYP modified polycrystalline ITO electrode offers the potential for electrochemically evaluating CYP activity for drug metabolism with a simple configuration.

Design and fabrication of biosensing interface for waveguide-mode sensor.

In order to develop a biosensing system with waveguide-mode sensor, fabrication of a biosensing interface on the silica surface of the sensing chip was carried out using triethoxysilane derivatives with anti-leptin antibody. Triethoxysilane derivatives bearing succinimide ester and oligoethylene glycol moieties were synthesized to immobilize the antibody and to suppress nonspecific adsorption of proteins, respectively. The chip modified with triethoxysilane derivatives bearing oligoethylene glycol moiety suppressed nonspecific adsorption of proteins derived from human serum effectively by rinse with PBS containing surfactant (0.05% Tween 20). On the other hand, it was confirmed that antibody was immobilized on the chip by immersion into antibody solution to show response of antigen-antibody reaction, where the chip was modified with triethoxysilane derivatives bearing succinimide ester moiety. When the interface was fabricated with antibody and a mixture of triethoxysilane derivatives bearing succinimide ester and oligoethylene glycol moieties, the response of antigen-antibody reaction depended on composition of the mixture and enhanced with the increase of ratio for triethoxysilane derivatives bearing succinimide ester moiety reflecting the antibody concentration immobilized on the chip. While introduction of excess triethoxysilane derivatives bearing succinimide ester moiety induced nonspecific adsorption of proteins derived from human serum, the immobilized antibody on the chip kept its activity after 1-month storage in a refrigerator. Taking into consideration those factors, the biosensing interface was fabricated using triethoxysilane derivatives with anti-leptin antibody to examine performance of the waveguide-mode sensor. It was found that the detection limits for human leptin were 50 ng/mL in PBS and 100 ng/mL in human serum. The results demonstrate that the waveguide-mode sensor powered by the biosensing interface fabricated with those triethoxysilane derivatives and antibody has potential to detect several tens of nanograms per milliliter of biomarkers in human serum with an unlabeled detection method.

Design of biomolecular interface for detecting carbohydrate and lectin weak interactions.

A hybrid functional biomolecular interface designed at a molecular size level is very effective at capturing an analyte with high sensitivity even if the interaction is very weak, as when detecting proteins with carbohydrate. We designed and processed a protein (lectin) recognition molecular interface taking the following points into consideration: (1) the height (molecular length) difference between the capturing and spacer molecules; (2) the ratio of capturing molecules in the recognition interface. When the height difference between the maltoside part (Concanavalin A (Con A) recognition group) and the OH group terminated spacer molecules exceeded (>(CH(2))(6)), the association rate constant (k(a)) became larger (k(a)(1/Ms): ∼2.6 times) and the dissociation constant (K(D)) became much smaller (K(D)(M): 1.0 × 10(-6): ∼0.17 times) compared with the similar heights (lengths) of both molecular interfaces. With regard to maltoside density, a 100% maltoside monolayer was unsuitable for detecting Con A. We constructed a nanostructured recognition site with a maltoside part of 10%, which was the most suitable ratio for Con A detection. The binding interaction between Con A and the maltoside group was changed from monovalent binding to bivalent binding when the maltoside part was diluted in the recognition interface. From electrochemical measurements, even though there was a small amount of maltoside component on the suitable recognition monolayer, quality similar to that of 100% maltoside was observed.

Lower effectiveness of intravenous steroid treatment for moderate-to-severe ulcerative colitis in hospitalised patients with older onset: a multicentre cohort study.

BACKGROUND: The increasing incidence of older-onset ulcerative colitis (UC), which has a higher risk of surgery, is a global health issue. However, data regarding intravenous steroid treatment, one of the important treatment options to avoid surgery, for older-onset UC is lacking. AIMS: To evaluate the association between onset age and effectiveness of intravenous steroids in UC. METHODS: This retrospective multicentre (27 facilities) cohort study included moderate-to-severe hospitalised UC patients who underwent their first intravenous steroids between April 2014 and July 2019. The primary outcome was clinical remission at day 30, using two-item patient-reported outcome scoring. The key secondary outcomes were risks of surgery and adverse events (death, infection and venous thrombosis) within 90 days. A modified Poisson regression model was used for analysis. RESULTS: Overall, 467 UC patients (384 younger-onset and 83 older-onset) were enrolled. Clinical remission at day 30 was observed in 252 (65.6%) among younger-onset patients and 43 (51.8%) among older-onset patients (adjusted risk difference, -21.7% [95% CI, -36.1% to -7.2%]; adjusted risk ratio [ARR], 0.74 [95% CI, 0.59 to 0.93]). The risks of surgery and adverse events were higher in older-onset UC (20.5% vs. 3.1%; ARR, 8.92 [95% CI, 4.13 to 19.27], 25.3% vs. 9.1%; ARR, 2.19 [95% CI, 1.22 to 3.92], respectively). Four deaths occurred, all involving older-onset UC. The risks of infection and venous thrombosis were also higher in older-onset UC (18.1% vs. 8.6%, 7.2% vs. 0.5%, respectively). CONCLUSIONS: Older-onset was associated with a lower effectiveness of intravenous steroids with higher risks of surgery and adverse events in UC.

Kidney-specific overexpression of Sirt1 protects against acute kidney injury by retaining peroxisome function.

Sirt1, a NAD-dependent protein deacetylase, is reported to regulate intracellular metabolism and attenuate reactive oxidative species (ROS)-induced apoptosis leading to longevity and acute stress resistance. We created transgenic (TG) mice with kidney-specific overexpression of Sirt1 using the promoter sodium-phosphate cotransporter IIa (Npt2) driven specifically in proximal tubules and investigated the kidney-specific role of Sirt1 in the protection against acute kidney injury (AKI). We also elucidated the role of number or function of peroxisome and mitochondria in mediating the mechanisms for renal protective effects of Sirt1 in AKI. Cisplatin-induced AKI decreased the number and function of peroxisomes as well as mitochondria and led to increased local levels of ROS production and renal tubular apoptotic cells. TG mice treated with cisplatin mitigated AKI, local ROS, and renal tubular apoptotic tubular cells. Consistent with these results, TG mice treated with cisplatin also exhibited recovery of peroxisome number and function, as well as rescued mitochondrial function; however, mitochondrial number was not recovered. Immunoelectron microscopic findings consistently demonstrated that the decrease in peroxisome number by cisplatin in wild type mice was restored in transgenic mice. In HK-2 cells, a cultured proximal tubule cell line, overexpression of Sirt1 rescued the cisplatin-induced cell apoptosis through the restoration of peroxisome number, although the mitochondria number was not restored. These results indicate that Sirt1 overexpression in proximal tubules rescues cisplatin-induced AKI by maintaining peroxisomes number and function, concomitant up-regulation of catalase, and elimination of renal ROS levels. Renal Sirt1 can be a potential therapeutic target for the treatment of AKI.

Surface modification of GC and HOPG with diazonium, amine, azide, and olefin derivatives.

Surface modification of glassy carbon (GC) and highly oriented pyrolytic graphite (HOPG) was carried out with diazonium, amine, azide, and olefin derivatives bearing ferrocene as an electroactive moiety. Features of the modified surfaces were evaluated by surface concentrations of immobilized molecule, blocking effect of the modified surface against redox reaction, and surface observation using cyclic voltammetry and electrochemical scanning tunneling microscope (EC-STM). The measurement of surface concentrations of immobilized molecule revealed the following three aspects: (i) Diazonium and olefin derivatives could modify substrates with the dense-monolayer concentration. (ii) The surface concentration of immobilized amine derivative did not reach to the dense-monolayer concentration reflecting their low reactivity. (iii) The surface modification with the dense-monolayer concentration was also possible with azide derivative, but the modified surface contained some oligomers produced by the photoreaction of azides. Besides, the blocking effect against redox reaction was observed for GC modified with diazonium derivative and for HOPG modified with diazonium and azide derivatives, suggesting fabrication of a densely modified surface. Finally, the surface observation for HOPG modified with diazonium derivative by EC-STM showed a typical monolayer structure, in which the ferrocene moieties were packed densely at random. On the basis of those results, it was demonstrated that surface modification of carbon substrates with diazonium could afford a dense monolayer similar to the self-assembled monolayer (SAM) formation.

Synthesis and galectin-binding activities of mercaptododecyl glycosides containing a terminal ß-galactosyl group.

Mercaptododecyl glycosides containing a terminal ß-galactosyl group were prepared from D-galactose or from D-lactose via hexa-O-acetyl-lactal (10) as a key intermediate. Interactions of these glycolipids (5 kinds) and galectins (ß-galactoside binding lectins, 6 species) were evaluated by surface plasmon resonance (SPR) method. High binding responses were observed for the lactoside, 2-deoxy-lactoside, and lactosaminide with some galectins (Gal-3, -4, -8), whereas the galactoside and 2,3-dideoxy-lactoside showed low binding activities.

Surface plasmon resonance analysis of interactions between diacylglycerol acyltransferase and its interacting molecules.

To measure the interactions of diacylglycerol acyltransferase (DGAT) by surface plasmon resonance (SPR), we immobilized Saccharomyces cerevisiae DGAT2 encoded by DGA1 on a BIACORE sensor chip surface. We used N-terminally truncated Dga1p with a FLAG tag at the C-terminus, which was purified to apparent homogeneity, maintaining significant DGAT activity (Kamisaka et al., Appl. Microbiol. Biotechnol., 88, 105-115 (2010)). Truncated Dga1p with a FLAG tag was immobilized with an anti-FLAG antibody that had been coupled with an L1 chip surface consisting of a carboxymethyl dextran matrix with additional hydrophobic alkane groups. The Dga1p-immobilized chip surface was analyzed for interactions of Dga1p with oleoyl-CoA, its substrate, and anti-Dga1p IgG, its interacting protein, by SPR. The binding of these analytes with the Dga1p-immobilized chip surface was specific, because butyryl-CoA, which cannot be used as a substrate for DGAT, and anti-glyceraldehyde-3-phosphate dehydrogenase IgG, did not induce any signals on SPR. Furthermore, injection of organic compounds such as xanthohumol, a DGAT inhibitor, into the Dga1p-immobilized chip surface induced significant SPR signals, probably due to interaction with DGAT. Another DGAT inhibitor, piperine, did not induce SPR signals on application, but induced them due to piperine on application together with oleoyl-CoA, in which piperine can be incorporated into the micelles of oleoyl-CoA. The results indicate that the Dga1p-immobilized L1 chip surface recognized DGAT inhibitors. Taking all this together, SPR measurement using the Dga1p-immobilized L1 chip surface provided a useful system to elucidate the structure-function relationships of DGAT and screen DGAT inhibitors.

One-step detection of galectins on hybrid monolayer surface with protruding lactoside.

Galectins, or beta-galactoside binding lectins, are detected deep in tumor tissue and are recognized as diagnostic and prognostic markers of cancer and other serious diseases. There is a need to develop a faster, easier, and simpler method for detecting galectins. We have succeeded in forming a mixed self-assembled monolayer (SAM) interface consisting of beta-galactoside terminated alkanethiol (lactoside protuberant dodecanethiol) and tri(ethylene glycol) (TEG) terminated short alkanethiol, which proved to be a superior protein resistant material, to enable us to develop a label-free, one-step, and highly sensitive system for detecting the expected biomarker, galectin. We successfully detected nanomolar level (~ 1 nM) galectin-4 and -8 on a 4% lactoside protrusive surface, even though the affinity between the galectins and lactoside was very weak (KD = 1 x 10(-3)~1 x 10(-6)). The combination of the suppression of background noise by filling with TEG terminated short alkanethiol and control of the ligand ratio in the interface contributed to the highly sensitive detection of galectin. We also detected galectin-4 at subten nanomolar levels even in a solution containing much higher concentrations of serum proteins (1800 times larger than the galectin concentration) without using molecule labeling or an immunological method.

Role of asymmetric dimethylarginine in vascular injury in transgenic mice overexpressing dimethylarginie dimethylaminohydrolase 2.

Dimethylarginie dimethylaminohydrolase (DDAH) degrades asymmetric dimethylarginine (ADMA), an endogenous nitric oxide (NO) synthase inhibitor, and comprises 2 isoforms, DDAH1 and DDAH2. To investigate the in vivo role of DDAH2, we generated transgenic mice overexpressing DDAH2. The transgenic mice manifested reductions in plasma ADMA and elevations in cardiac NO levels but no changes in systemic blood pressure (SBP), compared with the wild-type mice. When infused into wild-type mice for 4 weeks, ADMA elevated SBP and caused marked medial thickening and perivascular fibrosis in coronary microvessels, which were accompanied by ACE protein upregulation and cardiac oxidative stress. The treatment with amlodipine reduced SBP but failed to ameliorate the ADMA-induced histological changes. In contrast, these changes were abolished in transgenic mice, with a reduction in plasma ADMA. In coronary artery endothelial cells, ADMA activated p38 MAP kinase and the ADMA-induced ACE upregulation was suppressed by p38 MAP kinase inhibition by SB203580. In wild-type mice, long-term treatment with angiotensin II increased plasma ADMA and cardiac oxidative stress and caused similar vascular injury. In transgenic mice, these changes were attenuated. The present study suggests that DDAH2/ADMA regulates cardiac NO levels but has modest effect on SBP in normal conditions. Under the circumstances where plasma ADMA are elevated, including angiotensin II-activated conditions, ADMA serves to contribute to the development of vascular injury and increased cardiac oxidative stress, and the overexpression of DDAH2 attenuates these abnormalities. Collectively, the DDAH2/ADMA pathway can be a novel therapeutic target for vasculopathy in the ADMA or angiotensin II-induced pathophysiological conditions.

Sirt1 protects against oxidative stress-induced renal tubular cell apoptosis by the bidirectional regulation of catalase expression.

NAD(+)-dependent protein deacetylase Sirt1 regulates cellular apoptosis. We examined the role of Sirt1 in renal tubular cell apoptosis by using HK-2 cells, proximal tubular cell lines with or without reactive oxygen species (ROS), H(2)O(2). Without any ROS, Sirt1 inhibitors enhanced apoptosis and the expression of ROS scavenger, catalase, and Sirt1 overexpression downregulated catalase. When apoptosis was induced with H(2)O(2), Sirt1 was upregulated with the concomitant increase in catalase expression. Sirt1 overexpression rescued H(2)O(2)-induced apoptosis through the upregulation of catalase. H(2)O(2) induced the nuclear accumulation of forkhead transcription factor, FoxO3a and the gene silencing of FoxO3a enhanced H(2)O(2)-induced apoptosis. In conclusion, endogenous Sirt1 maintains cell survival by regulating catalase expression and by preventing the depletion of ROS required for cell survival. In contrast, excess ROS upregulates Sirt1, which activates FoxO3a and catalase leading to rescuing apoptosis. Thus, Sirt1 constitutes a determinant of renal tubular cell apoptosis by regulating cellular ROS levels.

Recognition of lectin with a high signal to noise ratio: carbohydrate-tri(ethylene glycol)-alkanethiol co-adsorbed monolayer.

Densely packed co-adsorbed ultrathin mono molecular layers of short tri(ethylene glycol)-alkanethiolate (for repelling proteins) and maltoside terminated alkanethiolate (for capturing lectin) provided an extremely high signal to noise ratio surface: the repelling molecules, which had two different functions (highly flexible-hydrophilic arm and rigid packing tail group), worked as "nano barriers" in the recognition monolayer.

12-Mercaptododecyl beta-maltoside-modified gold nanoparticles: specific ligands for concanavalin A having long flexible hydrocarbon chains.

A simple and highly specific protein detection system using glycoconjugated gold nanoparticles was investigated. This system was based on the aggregation of gold nanoparticles coated with carbohydrate alkanethiols in the presence of corresponding proteins (lectins) that had specific recognition for certain carbohydrates. In order to construct an efficient specific recognition system, maltoside alkanethiol was adopted as an effective sensing modifier having a disaccharide group and a flexible long alkyl chain. The surface modification of gold nanoparticles with maltoside alkanethiol resulted in a shift and broadening (from 520 to 610 nm) of the absorption peak. Monodispersed maltoside-adsorbed gold nanoparticles aggregated with the specific lectin, concanavalin A (Con A). This phenomenon was used to detect the presence of Con A and to estimate concentrations of Con A in sample solutions. The precipitate of the maltoside-gold nanoparticle-Con A mixture was redispersed by addition of methyl alpha-D-mannopyranoside whose adsorption coefficient is larger than that of maltoside with Con A.

[A case report of anaphylactoid purpura with acute abdominal pain secondary to trauma caused by traffic accident].

A 17-year-old man was admitted to our hospital with multiple fractures resulting from traffic accident. After treatment of fractures, his general status was improved. However, one month after traffic accident, he suffered severe pain in the epigastrium. Ultrasonography and computed tomography showed thickening of the intestinal wall in the duodenum, ileum, and ascending colon. Nineteen days after the onset of abdominal pain, small hemorrhagic spots appeared on both of the lower legs. Subsequently, he developed proteinuria and hematuria. Purpura nephritis was diagnosed in biopsy specimens of the kidney. Anaphylactoid purpura associated with traffic accident is very rare and it is difficult to diagnose without skin and renal symptoms.

Rho-kinase as a molecular target for insulin resistance and hypertension.

Rho-kinase plays an important role in hypertension and is reported to interfere with insulin signaling through serine phosphorylation of insulin receptor substrate-1 (IRS-1) in cultured vascular smooth muscle cells. We therefore examined the role of Rho-kinase in the development of insulin resistance in Zucker obese rats. In skeletal muscles and aortic tissues of Zucker obese rats, activation of RhoA/Rho-kinase was observed. Long-term Rho-kinase inhibition by 4 wk treatment with fasudil (a Rho-kinase inhibitor) not only reduced blood pressure but corrected glucose and lipid metabolism, with improvement in serine phosphorylation of IRS-1 and insulin signaling in skeletal muscles. Direct visualization of skeletal muscle arterioles with an intravital CCD videomicroscope demonstrated that both acetylcholine- and sodium nitroprusside-induced vasodilations were blunted, which were restored by the fasudil treatment. Furthermore, both fasudil and Y-27632 prevented the serine phosphorylation of IRS-1 induced by insulin and/or tumor necrosis factor-alpha in skeletal muscle cells. Collectively, Rho-kinase is responsible for the impairment of insulin signaling and may constitute a critical mediator linking between metabolic and hemodynamic abnormalities in insulin resistance.

Dimethylarginine dimethylaminohydrolase 2 increases vascular endothelial growth factor expression through Sp1 transcription factor in endothelial cells.

OBJECTIVE: Dimethylarginie dimethylaminohydrolase (DDAH) is a degrading enzyme for asymmetrical dimethylarginine, an endogenous NO synthase inhibitor. The molecular mechanism for DDAH-induced vascular endothelial growth factor (VEGF) expression was examined. METHODS AND RESULTS: Although the transfection of expression vectors for 2 isoforms of DDAH, DDAH1, or DDAH2 increased DDAH activity in bovine aortic endothelial cells and human umbilical vein endothelial cells, expression and secretion of VEGF were increased only in DDAH2-transfected cells. Knocking down the DDAH2 gene reduced VEGF production, and DDAH2 overexpression enhanced both proliferation and migration of endothelial cells. The VEGF promoter activity was increased by DDAH2 transfection, which was not blocked by an NO synthase (NOS) inhibitor but required the Sp1 sites. DDAH2 overexpression increased nuclear protein levels bound to Sp1 oligonucleotides in endothelial cells. Sp1 small interfering RNA blocked DDAH2-induced upregulation of VEGF. DDAH2 transfection increased nuclear and threonine-phosphorylation levels of Sp1 in a protein kinase A (PKA)-dependent manner. Protein-protein interaction between DDAH2 and PKA was enhanced in DDAH2-transfected cells. CONCLUSIONS: DDAH2 upregulated the expression of VEGF through Sp1-dependent and NO/NOS system-independent promoter activation. DDAH2-increased Sp1 DNA binding activity was PKA dependent. These mechanisms may provide a novel therapeutic strategy for VEGF-related vasculopathies such as atherosclerosis.

Selective decrease in colonic CD56(+) T and CD161(+) T cells in the inflamed mucosa of patients with ulcerative colitis.

AIM: To investigate the role of local colonic mucosal NK receptor-positive T (NKR(+) T) cells in the regulation of intestinal inflammation, we analyzed the population and function of these cells in ulcerative colitis (UC). METHODS: Colonic mucosal tissues were obtained from colonoscopic biopsies of the descending colon from 96 patients with UC (51 endoscopically uninflamed, 45 inflamed) and 18 normal controls. Endoscopic appearance and histologic score at the biopsied site were determined by Matts' classification. A single cell suspension was prepared from each biopsy by collagenase digestion. Two NKR(+) T cell subsets, CD56(+) (CD56(+)CD3(+)) T cells and CD161(+) (CD161(+)CD3(+)) T cells, were detected by flow cytometric analysis. Intracellular cytokine analysis for anti-inflammatory cytokine interleukin-10 (IL-10) was performed by in vitro stimulation with phorbol-myristate-acetate (PMA) and ionomycin. RESULTS: CD56(+) T cells and CD161(+) T cells are present in the normal human colon and account for 6.7% and 21.3% of all mononuclear cells, respectively. The populations of both CD56(+) T cells and CD161(+) T cells were decreased significantly in the inflamed mucosa of UC. In contrast, the frequency of conventional T cells (CD56(-)CD3(+) cells and CD161(-)CD3(+) cells) was similar among the patient and control groups. The populations of NKR(+) T cells were correlated inversely with the severity of inflammation, which was classified according to the endoscopic and histologic Matts' criteria. Interestingly, approximately 4% of mucosal NKR(+) T cells expressing IL-10 were detected by in vitro stimulation with PMA and ionomycin. CONCLUSION: Selective reduction in the population of colonic mucosal NKR(+) T cells may contribute to the development of intestinal inflammation in UC.