主要组织相容性复合物Ⅰ类链相关基因在肠组织中的表达及与溃疡性结肠炎的关系

目的 探讨主要组织相容性复合物Ⅰ类链相关基因(MIC)在溃疡性结肠炎(UC)发病中所起的作用.方法 采用荧光定量实时-聚合酶链反应(RT-PCR)方法检测34例UC患者和17例正常人肠黏膜组织中MICA和MICB及其受体NKG2D mRNA表达水平的差异.采用激光共聚焦显微镜观察肠黏膜组织中MICA分子的表达定位.结果 UC组MICA、MICB及NKG2DmRNA水平的表达量(分别为3.5408±2.6658、8.9879±3.2893和2.4395±0.8147)均显著高于正常对照组(分别为1.0477±0.7201、4.6293±1.2616和1.1624±0.3954,P值分别=0.0053、0.0039和0.0078).免疫荧光共聚焦显微镜观察显示,MICA分子在肠上皮细胞胞膜中表达.结论 UC患者肠黏膜组织中MICA、MICB及其受体NKG2D的mRNA表达水平均增高,提示MIC基.因在UC局部起重要作用.     

Functional MICA-129 polymorphism and serum levels of soluble MICA are correlated with ulcerative colitis in Chinese patients

Background and Aim: The aim of the present study was to evaluate the contribution of the dimorphism (MICA‐129 val and met) to the genetic susceptibility and functions of ulcerative colitis (UC) in patients in central China. Methods: Genotyping of MICA‐129 was performed in 272 consecutive UC patients and 560 age‐ and sex‐matched healthy individuals by using a polymerase chain reaction‐sequencing based typing (PCR‐SBT) method. A total of 93 patients and 98 healthy individuals serum soluble MICA (sMICA) concentrations were detected by enzyme‐linked immunosorbent assay. Results: Both the frequencies of the variant allele (val) and genotype (val/val) in the MICA‐129 gene were significantly higher in UC patients than in the controls (77.4% vs 71.7%, P = 0.015, 95% confidence interval [CI]: 1.064–1.716; 56.9% vs 46.4%, P = 0.005, 95% CI: 1.142–2.047). Serum sMICA levels were significantly higher in UC patients than in the controls (560 ± 140 pg/mL vs 157 ± 67 pg/mL, P < 0.0001). The genotype also affected the extent and the activity of UC. Furthermore, patients with the MICA‐129 val/val genotype had higher serum sMICA levels than those with the val/met + met/met genotype (661 ± 352 SD pg/mL vs 523 ± 245 SD pg/mL, 95% CI: 13.47–265.35, P = 0.03). In addition, patients with severe colitis were more susceptible to higher levels of sMICA than those with mild colitis. Conclusions: Our findings showed that the MICA‐129 gene polymorphism as a functionally relevant gene was associated with UC and seems to play a potential role in the development of UC in patients in central China.     

Tripterygium glycosides suppress production of interleukin‐4 by splenocytes in oxazolone‐induced murine colitis

OBJECTIVE: To investigate the in vitro effect of Tripterygium glycosides (TG) on cytokine production by splenocytes in oxazolone (OXZ)‐induced colitis in mice. METHODS: Oxazolone (6 mg in 50% ethanol) was administered to male SJL/J mice intrarectally to induce colitis and the mice were killed 3 days later. Isolated splenocytes were cultured for 24 h in the presence of phorbol myristate acetate and ionomycin. A preparation of Tripterygium glycosides at a concentration of either 0.1 mg/mL or 0.01 mg/mL was added to the culture medium of splenocytes. Production of interferon gamma (IFN‐γ) and interleukin‐4 (IL‐4) in the supernatant were measured by ELISA. RESULTS: Production of IFN‐γ in the normal control group was suppressed by TG at both concentrations (0.01 and 0.1 mg/mL; 1.24 ± 0.13 pg/mL (samples without TG) → 0.97 ± 0.26 pg/mL (0.01 mg/mL TG) → 0.87 ± 0.18 pg/mL (0.1 mg/mL TG); P < 0.02) in a dose dependent manner. In the OXZ‐induced colitis group, the basic level of IFN‐γ was significantly lower than that of the normal control group (1.24 ± 0.13 pg/mL vs 0.65 ± 0.08 pg/mL; P < 0.01); but IL‐4 production was significantly increased in the OXZ‐induced colitis without TG group (7.83 ± 0.69 pg/mL vs 5.65 ± 0.48 pg/mL, P < 0.01). In both groups, TG suppressed IL‐4 production in a dose‐dependent manner (normal control group: 5.65 ± 0.48 pg/mL (samples without TG) → 4.97 ± 0.38 pg/mL (0.01 mg/mL TG) → 3.98 ± 0.32 pg/mL (0.1 mg/mL TG), P < 0.01; OXZ group: 7.83 ± 0.69 pg/mL (samples without TG) → 7.07 ± 0.47 pg/mL (0.01 mg/mL TG) → 6.35 ± 0.48 pg/mL (0.1 mg/mL TG), P < 0.01). CONCLUSION: Oxazalone‐induced IL‐4 overproduction by splenocytes was significantly suppressed by TG in a dose dependent manner and the beneficial effects of TG on ulcerative colitis might be related to the suppression of the Th2 type (e.g. IL‐4) mediated immunological response of splenocytes.     

Down-regulation of NKG2D and NKp80 ligands by Kaposi's sarcoma-associated herpesvirus K5 protects against NK cell cytotoxicity

Natural killer (NK) cells are important early mediators of host immunity to viral infections. The NK activatory receptors NKG2D and NKp80, both C-type lectin-like homodimeric receptors, stimulate NK cell cytotoxicity toward target cells. Like other herpesviruses, Kaposi's sarcoma-associated herpesvirus (KSHV) down-regulates MHC class I molecules to avoid detection by cytotoxic T lymphocytes but renders cells susceptible to NK cell cytotoxicity. We now show that the KSHV immune evasion gene, K5, reduces cell surface expression of the NKG2D ligands MHC class I-related chain A (MICA), MICB, and the newly defined ligand for NKp80, activation-induced C-type lectin (AICL). Down-regulation of both MICA and AICL requires the ubiquitin E3 ligase activity of K5 to target substrate cytoplasmic tail lysine residues. The common MICA *008 allele has a frameshift mutation leading to a premature stop codon and is resistant to down-regulation because of the loss of lysine residues. K5-mediated ubiquitylation signals internalization but not degradation of MICA and causes a potent reduction in NK cell-mediated cytotoxicity. The down-regulation of ligands for both the NKG2D and NKp80 activation pathways provides KSHV with a powerful mechanism for evasion of NK cell antiviral functions.     

Functional expression and release of ligands for the activating immunoreceptor NKG2D in leukemia

NKG2D ligands (NKG2DLs) mark malignant cells for recognition by natural killer (NK) cells and cytotoxic T lymphocytes via the activating immunoreceptor NKG2D. This led to the hypothesis that NKG2DLs play a critical role in tumor immune surveillance. The human NKG2DLs MICA and MICB are expressed on tumors of epithelial origin in vivo. For the other recently described set of human NKG2DLs, the UL16-binding proteins (ULBPs), expression in vivo is as yet undefined. In this study we investigated expression and function of NKG2DLs in leukemia using a panel of newly generated NKG2DL-specific monoclonal antibodies. We report that leukemia cells from patients variously express MIC and ULBP molecules on the cell surface with MICA most frequently detected. Patient leukemia cells expressing MICA were lysed by NK cells in an NKG2D-dependent fashion. Sera of patients, but not of healthy donors, contained elevated levels of soluble MICA (sMICA). We also detected increased sMICB levels in patient sera using a newly established MICB-specific enzyme-linked immunosorbent assay. Reduction of leukemia MIC surface expression by shedding may impair NKG2D-mediated immune surveillance of leukemias. In addition, determination of sMICA and sMICB levels may be implemented as a prognostic parameter in patients with hematopoietic malignancies.     

Impact of gluten consumption in patients with functional dyspepsia: A case–control study

Background and Aim

Dietary factors and immune dysfunction may induce symptoms in patients with functional dyspepsia (FD). The aim of the study was to evaluate whether gluten consumption impacts symptom onset in patients with FD and to evaluate for possible histologic alterations in the duodenum of patients with FD.

Methods

We prospectively enrolled 101 patients newly diagnosed with FD and 31 asymptomatic controls. Specific FD symptoms and gluten consumption patterns were evaluated by self‐reported questionnaires. Tight junction protein (claudin‐1) expression and presence of intraepithelial lymphocyte (IEL) infiltration in the bulb (D1) and second portion (D2) of the duodenum were assessed by immunohistochemistry.

Results

Wheat bun consumption had higher frequency (P = 0.047) and increased average consumption (P = 0.01) scores in patients with FD compared with the control group. Of the 101 patients with FD, early satiety (P = 0.03) was associated with increased wheat bun consumption frequency score. On histologic evaluation, claudin‐1 expression was decreased in D1 (0.003 ± 0.001 vs 0.012 ± 0.002, P = 0.003) and D2 (0.002 ± 0.0004 vs 0.012 ± 0.001, P < 0.001), while duodenal IEL counts were increased in D1 (15.5 ± 7.8 vs 3.1 ± 2.5, P < 0.001) and D2 (20.6 ± 7.7 vs 5.8 ± 3.4, P < 0.001) among patients with FD compared with the control group. Finally, Helicobacter pylori infection was associated with increased IELs in D1 (20.6 ± 7.0 vs 14.2 ± 7.4, P = 0.001) among patients with FD.

Conclusions

Among patients with FD, gluten‐rich food may lead to symptom onset, specifically early satiety. Intestinal epithelial barrier dysfunction characterized by decreased claudin‐1 expression and mucosal immune activation demonstrated by IEL infiltration may contribute to the pathogenesis of FD.     

Impaired Detoxication of Hydrogen Sulfide in Ulcerative Colitis?

Impaired butyrate oxidation and raised counts of sulfate-reducing bacteria in the colon of patients with ulcerative colitis (UC) indicate that the disease may be induced or aggravated by hydrogen sulfide toxicity. We aimed to examine enzymatic removal of H₂S in erythrocytes and colonic mucosa from controls and patients with UC and Crohn's disease (CD). Rhodanese (RHOD) and thiol methyltransferase (TMT) activities were measured in rectal mucosa and erythrocytes, and plasma thiocyanate was determined. Four groups were analyzed: patients with UC, patients with CD, hospital controls (patients with dyspepsia or IBS), and a group of healthy volunteers. RHOD and TMT activity in rectal biopsies did not differ significantly between controls and patients with UC or CD (n=56). Control levels of RHOD were significantly higher in men than in women (212±25 and 132±14 nmol/mg/min, respectively; P<0.01). In erythrocytes (n=128) RHOD activity was significantly higher in UC patients than in hospital or volunteer controls (1.15±0.12 compared with 0.88±0.12 and 0.66±0.02 nmol/mg/min; P<0.05 and P<0.02, respectively). TMT activity was also significantly higher in erythrocytes from UC patients and hospital controls than volunteer controls (2.02±0.13 pmol/mg/min [P<0.001], 1.51±0.21 pmol/mg/min [P<0.05], and 1.17±0.18 pmol/mg/min, respectively). We found no evidence of defective enzymic detoxication of sulfide by RHOD or TMT in patients with UC or CD.     

Early IL‐10 predominant responses are associated with progression to chronic hepatitis C virus infection in injecting drug users

Summary. The critical events in clearance or persistence of hepatitis C virus (HCV) infection are unknown but likely to be determined early in acute infection. Type 1 and type 2 cytokine production was assessed by HCV peptide ELISpot and multiplex in vitro cytokine production assays in longitudinally collected samples from 20 untreated participants enrolled in the Australian Trial in Acute Hepatitis C (ATAHC); a prospective cohort of acute HCV infection (77% injecting drug users, IDU). Significantly higher interleukin‐10 (IL‐10) production (P = 0.048), in the relative absence of interferon‐gamma (IFN‐γ) and IL‐2 production, was present early in HCV infection in those who progressed to chronic infection. In contrast, viral clearance was associated with a greater magnitude and broader specificity of IFN‐γ (magnitude P < 0.001, breadth P = 0.004) and IL‐2 responses, in the relative absence of IL‐10. Early IL‐10 production was correlated with higher HCV RNA level at baseline (P = 0.046) and week 12 (P = 0.018), while IFN‐γ and IL‐2 production was inversely correlated with HCV RNA level at baseline (IFN‐γP = 0.020, IL‐2 P = 0.050) and week 48 (IFN‐γP = 0.045, IL‐2 P = 0.026). Intracellular staining (ICS) indicated the HCV‐specific IFN‐γ response was primarily from CD8⁺ T cells and NK cells, whereas IL‐10 production was predominantly from monocytes, with a subset of IL‐10 producing CD8⁺ T cells present only in those who progressed to chronic infection. IL‐10, an immunoregulatory cytokine, appears to play a key role in progression to chronic HCV infection.     

Telomere shortening in the colonic mucosa of patients with ulcerative colitis

Telomere length in human somatic cells gradually decreases with the number of cell divisions and is regarded as a marker of somatic cell turnover. Mucosal cells of the affected colon show rapid turnover in individuals with active ulcerative colitis (UC). Telomere length was determined by Southern blot analysis of terminal restriction fragments (TRFs) from the colonic mucosa of 17 patients with UC in remission, two of whom showed dysplasia, and 17 control subjects without colitis. For each individual, mean TRF length was compared between rectal mucosa and unaffected cecal mucosa. The mean TRF length of the rectal mucosa was significantly less than that of cecal mucosa in UC patients (7.87 ± 0.36 kb versus 8.77 ± 0.21 kb; P = 0.0015, Wilcoxon signed rank test), whereas no significant difference was detected in the control subjects. The extent of telomere shortening was 10.6 ± 3.35% in UC patients, compared with 0.8 ± 0.64% in noncolitis controls (P = 0.0024, Mann-Whitney U-test). Four UC patients, two of whom had dysplasia, showed telomere shortening of more than 20% in the rectal mucosa. These observations suggest that telomere shortening in the colonic mucosa of individuals with UC may represent the history of mucosal inflammation during disease of long duration, and that it may contribute to aneuploidy in UC. (Received May 6, 1997; accepted Sept. 26, 1997)     

Hepatitis B virus‐induced hepatocellular carcinoma: functional roles of MICA variants

Hepatitis B virus infection is a high‐risk factor for hepatocellular carcinoma. The human major histocompatibility complex class I chain‐related gene A (MICA) is a ligand of the NKG2D receptor that modulates the NK and T‐cell‐mediated immune responses and is associated with several diseases. This study determined the effects of MICA polymorphisms during HBV infection and HBV‐induced HCC. We conducted a case–controlled study in a Vietnamese cohort and genotyped ten functional MICA polymorphisms including the microsatellite motif in 552 clinically classified hepatitis B virus patients and 418 healthy controls. The serum soluble MICA levels (sMICA) were correlated with MICA variants and liver enzyme levels. We demonstrated a significant contribution of MICA rs2596542G/A promoter variant and nonsynonymous substitutions MICA‐129Met/Val, MICA‐251Gln/Arg, MICA‐175Gly/Ser, triplet repeat polymorphism and respective haplotypes with HBV‐induced HCC and HBV persistence. The circulating sMICA levels in HBV patient groups were elevated significantly compared with healthy controls. A significant contribution of studied MICA variants to sMICA levels was also observed. The liver enzymes alanine amino transferase (ALT), aspartate transaminase (AST), total bilirubin and direct bilirubin were positively correlated with sMICA levels suggesting sMICA as a biomarker for liver injury. We conclude that MICA polymorphisms play a crucial role in modulating innate immune responses, tumour surveillance and regulate disease susceptibility during HBV infection.     

Differential IFN‐γ production by adult and neonatal blood CD56+ natural killer (NK) and NK‐like‐T cells in response to Trypanosoma cruzi and IL‐15

Early interferon‐gamma (IFN‐γ) release by innate cells is critical to direct type 1 immune response able to control intracellular pathogens like Trypanosoma cruzi. Although CD56^bright natural killer (NK) cells are reported to be potent early IFN‐γ producers, other CD56⁺ cells like CD56^dim NK cells and NK‐like T cells have recently been shown to also release IFN‐γ. We have here studied the contribution of each CD56⁺ lymphocyte populations in early IFN‐γ production in both adults and neonates. On this purpose, we analysed the kinetics of IFN‐γ production by RT‐PCR, ELISA and flow cytometry from 2 h onwards after T. cruzi and IL‐15 stimulation and sought for the responding CD56⁺ cells. CD56^bright and CD56^dimCD16^? NK cells were the more potent IFN‐γ early producers in response to IL‐15 and parasites in adults and neonates. In both age groups, the majority of IFN‐γ producing cells were NK cells. However, on the contrary to neonates, CD3⁺CD56⁺ NK‐like T cells and CD3⁺CD56^? ‘classical’ T cells also contributed to early IFN‐γ production in adults. Altogether, our results support that whereas NK cells responded almost similarly in neonates and adults, cord blood innate CD56⁺ and CD56^? T cells displayed major quantitative and qualitative defects that could contribute to the well‐known neonatal immune immaturity.     

Effects of improved glycaemic control on endothelial function in patients with type 2 diabetes

Background: Patients with type 2 diabetes have abnormal endothelial function but it is not certain whether improvements in glycaemic control will improve endothelial function. Aims: To examine the effects of short‐term improved glycaemic control on endothelial function in patients with inadequately regulated type 2 diabetes mellitus. Methods: Forty‐three patients with type 2 diabetes and glycosylated haemoglobin (HbA_1c) > 8.9% were randomized to either improved glycaemic control (IC) n = 21 or usual glycaemic control (UC) n = 22 for 20 weeks. Using high‐resolution B‐mode ultrasound, brachial artery flow‐mediated dilatation (FMD) and glyceryl trinitrate‐mediated dilatation (GTN‐D) were measured at baseline and 20 weeks later. Results: After 20 weeks, HbA_1c was significantly lower in IC versus UC (IC 8.02 ± 0.25% versus UC 10.23 ± 0.23%, P < 0.0001) but changes in FMD and GTN‐D were not different between the groups (FMD at baseline and week 20 IC 5.1 ± 0.56% versus 4.9 ± 0.56% and UC 4.2 ± 0.51% versus 3.1 ± 0.51%; P = 0.23: GTN‐D IC 12.8 ± 1.34% versus 10.4 ± 1.32% and UC 13.7 ± 1.2% versus 12.7 ± 1.23%; P = 0.39). In the IC group weight increased by 3.2 ± 0.8 kg after 20 weeks compared to 0.02 ± 0.70 kg in UC (P = 0.003). Blood pressure and serum lipid concentrations did not change in either group. Conclusions: Short‐term reduction of HbA_1c levels did not appear to affect endothelial function in patients with type 2 diabetes and previously poorly regulated glycaemic control. (Intern Med J 2001; 31: 322–328)     

Functional T‐lymphocyte dichotomy in the peripheral blood of patients with unstable angina

OBJECTIVES. Herein, we investigated the percentage of T‐helper (Th1) and Th2 cells among the general T‐cell population in the peripheral blood of patients with stable angina (SA) and unstable angina (UA). BACKGROUND. Recent evidence suggests that Th1 cells and the cytokines that they secrete (especially IFN‐γ) have a role in the activation of macrophages, promotion of clot formation and destabilization of atherosclerotic plaques. Thus, Th1 cytokines may contribute to the initiation and progression of UA. In contrast, cytokines secreted by Th2 cells (e.g. IL‐10) are known to inhibit activation and proliferation of Th1 cells and the secretion of IFN‐γ, lysosomal enzymes and metalloproteinases. Therefore, we sought to examine whether the ratio of IFN‐γ to IL‐10 secreting cells is altered in patients with UA. METHODS. The percentage of Th1 and Th2 cells among the general T‐cell population was determined by fluorescent intracellular cytokine staining (IFN‐γ and IL‐10, out of the total CD3 positive cells). RESULTS. The percentage of T‐cells positive for intracellular IFN‐γ was significantly higher in patients with UA (n = 22) in comparison with SA (n = 20) patients (39.0±2.8% and 29.6±2.7%, respectively. P = 0.02). There was no significant difference in intracellular IL‐10 positive cells between the two groups. In addition, there was no significant difference in the ratio between the intracellular IFN‐γ positive cells and the intracellular IL‐10 positive cells. CONCLUSIONS. There is an increased activity of Th1 cells in patients with UA in comparison with patients with SA. There is no evidence of heightened activity of Th2 cells in either group. Thus, IFN‐γ secreted by peripheral blood T‐lymphocytes,may be an important immunomodulator contributing to destabilization of the atheromatous plaque lying at the base of the etiopathogenesis of unstable angina.     

Discrepant influence of vitamin D status on parathyroid hormone and bone mass after two years of calcium supplementation

Objective To investigate the influence of vitamin D status on parathyroid hormone and bone mass after a 2‐year supplementation of calcium alone. Patients and Methods Randomized, double‐blind, placebo‐controlled clinical trial, in healthy postmenopausal women without osteoporosis: three hundred and thirty‐six subjects aged 60–97 years were studied and randomized to receive elemental calcium 500 mg/day (n = 175) or placebo (n = 161) for 2 years. Measurements Changes in parathyroid hormone (PTH) and bone mineral density (BMD) from baseline and vitamin D status. Values are presented as means ± SD. Results After 2 years, subjects with calcium supplementation had significant decrease in plasma PTH level (4·4 ± 1·7 vs 4·7 ± 1·9 pmol/l, P < 0·01), improved lumbar BMD (1·031 ± 0·12 vs 1·004 ± 0·12 g/cm², P < 0·001) and total hip BMD (0·890 ± 0·10 vs 0·883 ± 0·10 g/cm², P < 0·001) without change in femoral neck BMD. In the placebo group, PTH level significantly increased (4·8 ± 1·6 vs 4·5 ± 1·5 pmol/l, P < 0·001), lumbar BMD slightly increased (1·027 ± 0·14 vs 1·018 ± 0·14 g/cm², P < 0·001), total hip and femoral neck BMD decreased (0·876 ± 0·11 vs 0·887 ± 0·11 g/cm², P < 0·001 and 0·783 ± 0·10 vs 0·798 ± 0·10 g/cm², P < 0·001, respectively). When subjects were classified according to baseline 25‐hydroxyvitamin D [25(OH)D] levels into those with 25(OH)D in the lower tertile (lowVitD) and those in the middle and upper tertiles combined (normVitD). The degree of PTH suppression after calcium supplementation was significantly higher in the normVitD compared to the lowVitD groups (?5·6 ± 26·7%vs 1·3 ± 27·2%, P < 0·05). No effect of vitamin D status on the change in lumbar BMD after calcium supplementation was demonstrated. Despite the higher suppression of PTH, there was a slight decrease in femoral neck BMD after calcium supplementation in the normVitD group while femoral neck BMD was more or less maintained in the lowVitD group (?0·6 ± 3·2%vs 0·5 ± 2·9%, P < 0·05). Conclusion Calcium supplementation appears to affect femoral bone mass less in Thai postmenopausal women with adequate vitamin D status, despite higher suppression of PTH.     

HLA class I, NKG2D, and natural cytotoxicity receptors regulate multiple myeloma cell recognition by natural killer cells

The role of natural killer (NK) cells in multiple myeloma is not fully understood. Here, NK susceptibility of myeloma cells derived from distinct disease stages was evaluated in relation to major histocompatibility complex (MHC) class I, MHC class I chain-related protein A (MICA), MHC class I chain-related protein B (MICB), and UL16 binding protein (ULBP) expression. MHC class I molecules were hardly detectable on bone marrow cells of early-stage myeloma, while late-stage pleural effusion-derived cell lines showed a strong MHC class I expression. Conversely, a high MICA level was found on bone marrow myeloma cells, while it was low or not measurable on pleural effusion myeloma cells. The reciprocal surface expression of these molecules on bone marrow- and pleural effusion-derived cell was confirmed at mRNA levels. While bone marrow-derived myeloma cells were readily recognized by NK cells, pleural effusion-derived lines were resistant. NK protection of pleural effusion cells was MHC class I dependent. Receptor blocking experiments demonstrated that natural cytotoxicity receptor (NCR) and NK receptor member D of the lectin-like receptor family (NKG2D) were the key NK activating receptors for bone marrow-derived myeloma cell recognition. In ex vivo experiments patient's autologous fresh NK cells recognized bone marrow-derived myeloma cells. Our data support the hypothesis that NK cell cytotoxicity could sculpture myeloma and represents an important immune effector mechanism in controlling its intramedullary stages.     

Prophylaxis of hepatic encephalopathy in acute variceal bleed: a randomized controlled trial of lactulose versus no lactulose

Background and Aims: Acute variceal bleed (AVB) is an important precipitating factor for development of hepatic encephalopathy (HE). However, there is paucity of data on the role of lactulose for prevention of HE after AVB. We evaluated the role of lactulose for prophylaxis of HE after AVB. Methods: Consecutive patients of cirrhosis with AVB enrolled. Patients included if >18 years old and had no HE at the time of presentation. Patients were randomized to receive lactulose (Group‐L) or no lactulose (Group‐P) along with standard treatment of AVB as per Baveno 4 guidelines. Primary endpoint was development of overt HE as per West Haven criteria within 120 h of randomization. Results: Seventy patients were randomized into group‐L (Gp‐L, n = 35) and group‐P (Gp‐P, n = 35). There was no significant difference in baseline characteristics between the two groups. Characteristics of variceal bleed were also similar (Gp‐L vs Gp‐P [mean arterial pressure 81.0 ± 10.5 vs 79.5 ± 9.9 mmHg], Hb [8.4 ± 1.5 vs 9.3 ± 2.3 g/dL], blood transfusion requirement [1.6 ± 1.1 vs 1.3 ± 0.9 units], time to endoscopy [6.3 ± 2.8 vs 7.0 ± 3.1 h], and esophageal source of bleed [92% vs 88%]). Nineteen (27%) patients developed HE; five patients (14%) in Gp‐L and 14 patients (40%) in Gp‐P, P = 0.03. The median grade of HE was 2 (range 2–4) and median time interval of development of HE after randomization was 2 days (range 1–4). Nine patients (13%) died; three (8.5%) patients in Gp‐L and six (17%) patients in Gp‐P, P = 0.23. Patients who developed HE had significantly higher baseline Child‐Turcotte‐Pugh score score (10.2 ± 1.2 vs 9.4 ± 1.4 P = 0.04), model for end stage liver disease score (18.2 ± 3.9 vs 15.4 ± 4.5 P = 0.02), arterial ammonia level (112.2 ± 22.7 vs 94.8 ± 17.6 umol/L, P = 0.001), baseline total leukocyte count (10 505.2 ± 8911.9 vs 5784.3 ± 3387.0 P = 0.002), total bilirubin (3.4 ± 1.3 vs 2.1 ± 1.8 mg%, P = 0.008) as compared to patients who did not develop HE. On multivariate analysis only baseline arterial ammonia, blood requirement during hospital stay and lactulose therapy were predictors of development of HE. Conclusions: Lactulose is effective in prevention of HE in patients with cirrhosis and acute variceal bleed.     

Reduced natural killer (NK) function associated with high-risk myelodysplastic syndrome (MDS) and reduced expression of activating NK receptors

Myelodysplastic syndromes (MDS) are characterized by ineffective hematopoiesis with potential for progression to acute myeloid leukemia (AML). We compared natural killer (NK) cytolytic function in 48 MDS patients with 37 healthy donors and found reduced activity in the patient population (K562 cytolysis, 19% +/- 21% SD versus 40% +/- 17%) (P < .001). NK cytotoxicity in MDS patients was reduced against 3 disparate tumor targets with differential activating receptor requirement, suggesting global defects in NK function. Reduced NK function in MDS was significantly associated with higher International Prognostic Score (P = .01), abnormal karyotype (P = .05), the presence of excess blasts (P = .01), and age-adjusted bone marrow hypercellularity (P = .04). MDS patients had a display of the activating receptor NKp30, and NKG2D down-regulation closely correlated with impaired NK function (P = .001). NKG2D ligands (MICA and MICB) were expressed on CD34(+) cells from bone marrow of 30% of MDS patients and a leukemic cell line derived from an MDS patient (MDS1). Collectively, these findings suggest that impairment of NK cytolytic function derives in part from reduced activating NK receptors such as NKG2D in association with disease progression. Evasion of NK immunosurveillance may have importance for MDS disease progression.     

Reduction in circulating markers of endothelial dysfunction in HIV-infected patients during antiretroviral therapy

Objectives

Antiretroviral therapy (ART) in HIV‐infected patients is associated with increased cardiovascular risk. Circulating markers of endothelial dysfunction may be used to study early atherogenesis. The aim of our study was to investigate changes in such markers during initiation of ART.

Methods

In 115 HIV‐positive treatment‐naïve patients, plasma lipids, E‐selectin, soluble intercellular adhesion molecule 1 (sICAM‐1), soluble vascular cell adhesion molecule 1 (sVCAM‐1), tissue‐type plasminogen activator inhibitor 1 (tPAI‐1) and high‐sensitivity C‐reactive protein (hsCRP) were measured before and after 2 and 14 months of ART. A control group of 30 healthy subjects was included. Values are mean±standard error of the mean.

Results

Prior to treatment, HIV‐infected patients had elevated levels of sICAM‐1 (296±24 vs. 144±12 ng/mL), tPAI‐1 (18 473±1399 vs. 5490±576 pg/mL) and hsCRP (28 060±5530 vs. 6665±2063 ng/mL) compared with controls (P<0.001). In contrast, sVCAM‐1 and E‐selectin did not differ between the groups. Initiation of ART resulted in significantly lower levels of E‐selectin (15.1±0.8; P<0.01), sICAM‐1 (248±12 ng/mL; P<0.05), sVCAM‐1 (766±33 ng/mL; P<0.001) and hsCRP (14 708±2358 ng/mL; P<0.001) after 2 months, which remained reduced at 14 months. tPAI‐1 was not influenced by initiation of ART.

Conclusions

Markers of endothelial dysfunction were elevated in treatment‐naïve HIV‐infected patients and were related to HIV RNA viral load. Initiation of ART reduced the levels of the majority of these markers. The positive effect of ART initiation was dependent on the duration of HIV infection prior to treatment.     

脱氧氮杂胞苷诱导HepG2细胞表达主要组织相容性复合体Ⅰ类分子A

目的 观察主要组织相容性复合体Ⅰ类分子A(MICA)在HepG2与L02细胞株中表达的差异及脱氧氮杂胞苷(5-aza-dC)对HepG2细胞株MICA表达的影响,探讨毛细血管扩张性共济失调突变蛋白(ATM)依赖的DNA损伤途径与5-aza-dC调节MICA表达的关系. 方法同时接种并培养L02和HepG2细胞,在同一时间点收取细胞,流式细胞仪检测细胞膜MICA蛋白表达水平;不同浓度5-aza-dC(0.1,1.0,5.0mmol/L)作用于HepG2细胞不同时间(24、48、72、96h)后,定量PCR检测MICA mRNA水平以寻找5-aza-dC最佳作用浓度和时间;ATM特异性抑制剂咖啡因或RNA干扰技术干扰ATM表达,定量PCR检测细胞mRNA水平,流式细胞术检测细胞膜MICA蛋白表达水平.结果 数据比较采用Kruskal-Wallis和Mean-Whitney U方差分析.结果 流式细胞结果显示,HepG2细胞高水平表达MICA,而正常肝细胞L02几乎不表达MICA;5-aza-dC处理可上调HepG2细胞MICA的表达(X2=7.20,P＜0.05),这种上调作用可被ATM特异性阻滞剂咖啡因和ATM特异的小分子干扰RNA所阻断(U=0.00,P＜0.05).结论 MICA在正常肝细胞株中无表达,在肝癌细胞株中高表达;5-aza-dC可诱导HepG2细胞MICA的表达,其机制可能与5-aza-dC引起的ATM依赖的DNA损伤途径有关.