PD-1/PDL1 and CD28/CD80 pathways modulate natural killer T cell function to inhibit hepatitis B virus replication

α-Galactosylceramide (α-GalCer)-activated natural killer T (NKT) cells have antiviral properties against hepatitis B virus (HBV). However, α-GalCer activation of NKT cells can induce anergy. We hypothesized that this effect may be overcome by a treatment strategy that includes manipulation of CD28/CD80 costimulatory and PD-1/PDL1 coinhibitory signals of NKT cells, thereby enhancing the anti-HBV effect of α-GalCer. We established a transgenic mouse model of chronic HBV infection and investigated hepatic NKT cell frequencies, functions and expression of immunomodulatory factors. Our results showed that compared with uninfected control mice, hepatic NKT cells from HBV transgenic mice displayed lower frequencies (7.91% vs 16.74%, P < 0.05), impaired capabilities to produce interferon (IFN)-γ (5.6% vs 1.4%, P < 0.05) and interleukin (IL)-4 (6.8% vs 0.3%, P < 0.05), higher expression of PD-1 (9.64% vs 6.36%, P < 0.05) and lower expression of CD28 (5.05% vs 28.88%, P < 0.05). However, when hepatic mononuclear cells (MNCs) were isolated from HBV transgenic mice, α-GalCer exposure in culture remarkably upregulated both PD-1(+) NKT cells (P < 0.05) and CD28(+) NKT cells (P < 0.05). Furthermore, when HBV transgenic mice were treated with combination therapies consisting of α-GalCer and anti-PDL1 monoclonal antibody (mAb) and/or anti-CD80/anti-CD28 mAbs, IFN-γ(+) NKT cell frequency was selectively increased (P < 0.05) and HBV replication was suppressed; these effects were accompanied by varying degrees and types of liver damage. Surprisingly, activating CD28/CD80 signal in HBV transgenic mice was more effective but caused less liver injury than blocking PD-1/PDL1 signal in modulating αGalCer-activated NKT cell function to inhibit HBV infection. Our findings also show that combined therapy with blocking PD-1/PDL1 and activating CD28/CD80 signal in the presence of aGalCer cannot superimpose the effect of antivirus. α-GalCer combination therapy that modulates the CD28/CD80 pathways of NKT cells may represent a promising approach to inhibit HBV replication in chronically infected patients.

The impact of intensifying acid suppression on sleep disturbance related to gastro-oesophageal reflux disease in primary care

BACKGROUND

Sleep disturbance is common in patients with GERD but there has been little evaluation of this problem in primary care in patients already taking therapy.

AIM

To evaluate the impact of administering a questionnaire (PASS test) to identify patients with sleep problems and evaluate the efficacy of esomeprazole to improve sleep disturbance in patients with GERD.

METHODS

This was a primary care based cluster-randomised, open-label study where practices were assigned to intervention or control groups. PASS test failures continued current therapy (control) or were switched to 4 weeks' once-daily esomeprazole 20 or 40 mg (intervention). Patients were evaluated at the end of 4 weeks and the outcomes that were assessed were the sleep questions from the Quality of Life in Reflux and Dyspepsia (QOLRAD) questionnaire and the presence or absence of sleep disturbance from the PASS test questionnaire.

RESULTS

A total of 1388 patients with evaluable data at 4 weeks were included in the analysis and 825 reported GERD-related sleep disturbance at baseline. At 4 weeks, 161 of 291 of control patients (55%) reported continued sleep disturbance compared to 120 of 534 (22.5%) of intervention patients [number needed to treat of 3: 95% confidence intervals (CI): 2.5-4]. There was a mean improvement in QOLRAD scores related to sleep in the intervention patients compared to control patients (mean improvement = 4.91; 95% CI: 3.73-6.09).

CONCLUSION

A PASS strategy identifies GERD patients with sleep disturbance in primary care that will benefit from a change in acid-suppressive therapy. ClinicalTrials.gov identifier: NCT00392002; study code: D9612L00096.

Zoledronate inhibits phosphate and bone morphogenetic protein 2-induced extracellular calcification of vascular smooth muscle cells in vitro

The aim of this study was to explore the effects of the bisphosphonate zoledronate on calcification induced by inorganic phosphate (Pi) and/or bone morphogenetic protein 2 (BMP-2) and the underlying mechanisms. Primary vascular smooth muscle cells (VSMCs) from rats were treated with 3 mM Pi or 3 mM Pi/BMP-2, with and without addition of zoledronate; 1.4 mM Pi served as a control. Calcium deposits, expression of core binding factor α-1 (Cbfa-1), osteopontin (OPN), parathyroid pituitary-specific transcription factor (Pit)-1 and Pit-2, and Pi uptake of VSMCs was determined. The calcification of VSMCs induced by elevated Pi or Pi/BMP-2 was significantly inhibited by zoledronate. The expression of Cbfa-1, OPN and Pit-1 was increased significantly after treatment with an elevated level of Pi or Pi/BMP-2, and this expression was significantly suppressed by addition of zoledronate. Pi uptake of VSMCs increased following treatment with elevated Pi and significantly decreased by addition of zoledronate. These results indicated that zoledronate effectively inhibited calcification induced by Pi/BMP-2, and this may have been achieved by means of the downregulation of expression of calcification-related proteins and uptake of Pi.

ASC-dependent RIP2 kinase regulates reduced PGE2 production in chronic periodontitis

Levels of prostaglandin E(2) (PGE(2)) and its processing enzyme, prostaglandin-endoperoxide-synthase-2/ cyclooxygenase-2 (PTGS2/COX-2), are elevated in actively progressing periodontal lesions, but suppressed in chronic disease. COX-2 expression is regulated through inflammatory signaling that converges on the mitogen-activated protein kinase (MAPK) pathway. Emerging evidence suggests a role for the inflammatory adaptor protein, ASC/Pycard, in MAPK activation. We postulated that ASC may represent a mediator of the MAPK-mediated regulatory network of PGE(2) production. Using RNAi-mediated gene slicing, we demonstrated that ASC regulates COX-2 expression and PGE(2) production in THP1 monocytic cells following infection with Porphyromonas gingivalis (Pg). Production of PGE(2) did not require the inflammasome adaptor function of ASC, but was dependent on MAPK activation. Furthermore, the MAP kinase kinase kinase CARD domain-containing protein RIPK2 was induced by Pg in an ASC-dependent manner. Reduced ASC and RIPK2 levels were revealed by orthogonal comparison of the expression of the RIPK family in ASC-deficient THP1 cells with that in chronic periodontitis patients. We show that pharmacological inhibition of RIPK2 represses PGE(2) secretion, and RNAi-mediated silencing of RIPK2 leads to diminished MAPK activation and PGE(2) secretion. These findings identify a novel ASC-RIPK2 axis in the generation of PGE(2) that is repressed in patients diagnosed with chronic adult periodontitis.

Social partnering significantly reduced rapid eye movement sleep fragmentation in fear-conditioned, stress-sensitive Wistar-Kyoto rats

Negative emotionality affects sleep-wake behavior in humans and rodents, and the Wistar-Kyoto (WKY) rat strain is known for its stress-sensitive phenotype. Analyzing rapid eye movement sleep (REMS) microarchitecture by separating REMS into single (siREMS; inter-REM episode interval>3 min) and sequential (seqREMS; interval≤3 min) episodes, we previously reported that cued fear conditioning (CFC) increased REMS fragmentation in WKY compared to Wistar rats by increasing the number of seqREMS episodes. Since social support affects fear responsiveness in humans, we hypothesized that social interaction with a naive partner would affect the sleep-wake response to CFC in WKY rats. Thus, male WKY rats were assigned to either the social support or the social isolation group. Animals were fear-conditioned to 10 tones (800 Hz, 90 dB, 5 s), each co-terminating with a mild foot shock (1.0 mA, 0.5 s), at 30-s intervals. All subjects underwent a tone-only test both 24 h (Day 1) and again two weeks (Day 14) later. Social partnering was achieved by providing the fear-conditioned rat with 30 min of interaction with its naive partner immediately after CFC and during the tone presentations on Day 1 and Day 14. The results indicate that while CFC increased freezing behavior in socially isolated WKY rats, it increased grooming behavior in socially partnered rats. Socially partnered rats had increased sleep efficiency during the light phase and spent less time in NREMS during the dark phase. The number of siREMS episodes increased during both the light and dark phases in partnered rats, and the number of seqREMS episodes increased in socially isolated rats. Our findings suggest that social partnering may protect WKY rats from the REMS fragmentation that is observed following CFC in isolation.

Quorum-sensing system in Acidithiobacillus ferrooxidans involved in its resistance to Cu²⁺

AIMS

 The purpose of this study was to search for the relationship between quorum sensing (QS) and Cu²⁺ resistance in Acidithiobacillus ferrooxidans.

METHODS AND RESULTS

 Resistance to Cu²⁺ of A. ferrooxidans significantly decreased with the treatment dose of a synthetic QS blocker (5Z)-4-bromo-5-(bromomethylene)-2(5H)-furanone (FUR). Relative differences in expression of the QS genes afeI, afeR and Cu²⁺ resistance-associated genes afe0329, afe0454 were examined in the presence of Cu²⁺ and/or FUR compound. The expression of QS genes afeI and afeR increased significantly with 50 mmol l⁻¹ Cu²⁺ in the culture, while for samples treated with both 50 mmol l⁻¹ Cu²⁺ and 0.01 μg ml⁻¹ FUR compound, they showed little changes compared with control, and the expression of afe0329 and afe0454 genes increased slightly either. These results showed that QS system was positively related to the mechanism of Cu²⁺ resistance.

CONCLUSIONS

QS system in A. ferrooxidans involved in its resistance to Cu²⁺.

SIGNIFICANCE AND IMPACT OF THE STUDY

 The mechanisms of Cu²⁺ resistance in A. ferrooxidans could be revealed on a population level rather than on a single-cell level. Our work also provides useful data for further selection of A. ferrooxidans strains with suitable Cu²⁺ resistance that could probably increase the bioleaching efficiency.

The use of hepatitis B core antibody-positive donor livers does not appear to have a deleterious effect on graft survival in liver transplantation for hepatitis C

INTRODUCTION

The use of hepatitis B core antibody-positive donor livers (HBcAb(+)) has steadily increased. According to a recent multivariate analysis of United Network for Organ Sharing (UNOS) data, there was no significant increase in the risk of using these donors. The increased risk among the hepatitis C virus (HCV)-positive subgroup noted in a univariate model disappeared upon multivariate analysis. However, deeper scrutiny may show that HCV-positive recipients may be at increased risk with HBcAb(+) donor livers, as they require simultaneous treatment with two antiviral regimens there may be deleterious interactions between the two viruses. Thus, the issue of HBcAb(+) donors for HCV-positive recipients merits more detailed analysis.

METHODS

Using UNOS registry data of all liver transplantations performed during the Model for End-Stage Liver Disease era from February 2002 through November 2007, we analyzed graft survival using Kaplan-Meier and Cox regression analyses.

RESULTS

Of the 12,543 HCV-positive recipients, 2,543 received HBcAb(-) livers and 853 received HBcAb(+) livers. While Kaplan-Meier analysis showed significantly lower graft survival among HCV-negative recipients of HBcAb(+) livers (P = .0001), there was no significant effect on graft survival among the HCV-positive population (P = .2). To detect an early effect in HCV-positive recipients, we examined 1-year graft survival, observing no significant difference (P = .3). To exclude a possible late effect, we examined graft survival in the HCV-positive population conditional upon surviving at least 1 year after transplantation; no significant difference was observed (P = .6). The elimination of potentially confounding codiagnoses, such as hepatitis B virus, alcoholism, acute graft failure, and hepatocellular cancer did not alter the findings. On univariate analysis, the lack of a significant effect persisted among the HCV population. However, the significant effect observed in the univariate model for the HCV-negative population became insignificant when combined with other risk factors in the multivariate model.

CONCLUSION

The use of HBcAb(+) livers in recipients with HCV did not appear to have a significant impact on graft survival.

Mechanism of adhesion maintenance by methionine sulphoxide reductase in Streptococcus gordonii

Methionine sulphoxide reductase maintains adhesin function during oxidative stress. Using Streptococcus gordonii as a model, we now show the mechanistic basis of adhesin maintenance provided by MsrA. In biofilms, S. gordonii selectively expresses the msrA gene. When the wild-type strain was grown with exogenous hydrogen peroxide (H(2)O(2)), msrA-specific mRNA expression significantly increased, while acid production was unaffected. In the presence of H(2)O(2), a msrA-deletion mutant (ΔMsrA) showed a 6 h delay in lag phase growth, a 30% lower yield of H(2)O(2), significantly greater inhibition by H(2)O(2) on agar plates (reversed by complementation), 30% less adhesion to saliva-coated hydroxyapatite, 87% less biofilm formation and an altered electrophoretic pattern of SspAB protein adhesins. Using mass spectrometry, methionine residues in the Met-rich central region of SspB were shown to be oxidized by H(2)O(2) and reduced by MsrA. In intact wild-type cells, MsrA colocalized with a cell wall-staining dye, and MsrA was detected in both cell wall and cytosolic fractions. To maintain normal adhesion and biofilm function of S. gordonii in response to exogenous oxidants therefore msrA is upregulated, methionine oxidation of adhesins and perhaps other proteins is reversed, and adhesion and biofilm formation is maintained.

Immunostimulatory activities of specific bacterial secondary metabolite of Anoxybacillus flavithermus strain SX-4 on carp, Cyprinus carpio

AIMS

  To determine the capacity of secondary metabolite of strain SX-4, to enhance the nonspecific immunity and survival of carp (Cyprinus carpio), and to identify the constituents that are responsible.

METHODS AND RESULTS

  A thermophilic strain SX-4 that is able to produce immunostimulatory metabolite was isolated from sludge sample of hot spring and identified by comparison with 16S rRNA sequences (99% of homology) as Anoxybacillus flavithermus. Bioactivity-guided fractionation of methanol extract from its cell-free culture, one bacterial peptide with the capacity of improving the nonspecific immune responses and disease resistance (relative per cent survival = 66·67%) was obtained and the compound was characterized as cyclo-(L-Pro-Gly) by IR, ESI-MS, (1) H NMR and (13) C NMR spectroscopic analyses. After intraperitoneal administration of this peptide, selected innate immune parameters including phagocytic activity, superoxide anion production, serum lysozyme activity and serum SOD activity, along with immune-related genes expression (i.e. interleukin-1β and inducible nitric oxide synthase), in the blood were found to be significantly increased.

CONCLUSIONS

  The bacterial peptide cyclo-(L-Pro-Gly) significantly enhances nonspecific immunity and survival of carp.

SIGNIFICANCE AND IMPACT OF THE STUDY

  There is a possibility of using cyclo-(L-Pro-Gly) as a better natural immunostimulant, which could have a promising role in aquaculture to prevent diseases and disease outbreaks.

Transretinal degeneration in ageing human retina: a multiphoton microscopy analysis

AIM

Retinal cell remodelling has been reported as a consistent feature of ageing. However, the degree to which this results in transretinal degeneration is unclear. To address this, the authors used multiphoton microscopy to quantify retinal degeneration in post-mortem human eyes of two age groups.

METHODS

Retinas from six young subjects (18-33 years old) and six older subjects (74-90 years old) were prepared as wholemount preparations. All retinas were stained with 4,6-diamidino-2-phenylindole and imaged by multiphoton confocal microscopy to quantify neuron densities in the retinal ganglion cell layer (RGCL), inner nuclear layer (INL) and outer nuclear layer (ONL). Neurons were counted using automated cell identification algorithms. All retinas were imaged hydrated to minimise tissue artefacts.

RESULTS

In both groups, 56% of the area within the central 4 mm eccentricity and 27% of the area with eccentricity between 4 mm and 7 mm were imaged. Compared with young subjects, the peak RGCL neuron loss in the aged subjects (25.5%) was at 1 mm eccentricity. INL and ONL neuron densities significantly decreased at 1-2 mm eccentricity (8.7%) and 0.5-4 mm eccentricity (15.6%) respectively (P <0.05). The reduction in neuron density in the INL corresponded, spatially, to the region with the greatest neuron loss in the RGCL and ONL.

CONCLUSIONS

This is the first study to correlate neurodegeneration in different populations of cells in the ageing retinas. These data confirm that the greatest neuronal loss occurs in the RGCL and ONL in human ageing retinas, whereas the INL is relatively preserved.