On the impact of hepatitis C virus and heterologous immunity on alloimmune responses following liver transplantation

Virus-induced heterologous immunity is considered a barrier to transplantation tolerance. Yet, hepatitis C (HCV)-infected liver transplant (LT) patients occasionally achieve operational tolerance. We investigated the mechanisms through which HCV infection modulates donor-specific T cell responses following LT and the influence of HCV eradication. We generated T cell lines from HCV-infected LT and non-LT patients before and after HCV eradication and quantified alloreactive responses using cell lines expressing single-HLA class-I antigens in the presence/absence of PD-1/CTLA-4 blockade. HCV-specific CD8+ T cells cross-reacted with allogeneic class-I HLA molecules. HCV-positive LT recipients exhibited a higher proportion of CD8+ T cells coexpressing inhibitory receptors (PD-1/CTLA4) than HCV-negative LT, and their expression correlated with CXCL10 plasma levels. This resulted in decreased antidonor and third-party proliferative responses, which were significantly reversed by HCV eradication. PD-1/CTLA-4 blockade increased the proportion of HCV-specific CD8+ T cells reacting against donor only before viral clearance. In conclusion, HCV infection results in the generation of HCV-specific CD8+ T cells capable of reacting against allogeneic HLA molecules. Following LT, this results in a PD-1/CTLA4-dependent decrease in alloimmune responses. Our findings challenge the notion that heterologous immunity is necessarily detrimental in LT and provide an explanation for the association between HCV eradication and immune-mediated allograft damage.

A Very Short Course of HBIg+NA Followed by Entecavir or Tenofovir Monotherapy Prevents HBV Recurrence in Low-Risk Liver Transplant Recipients

BACKGROUND

Monoprophylaxis with third-generation nucleos(t)ide analogues (NAs) can be safely adopted in hepatitis B virus (HBV)-positive, liver transplantation (LT) patients after at least 6 months of HBV immunoglobulin (HBIg)+NA. We investigated the efficacy of earlier initiation of post-LT entecavir (ETV) or tenofovir (TDF) monoprophylaxis.

METHODS

Between September 2011 and January 2017, all consecutive hepatitis B surface antigen (HBsAg)-positive transplanted patients were scheduled to receive HBIg with ETV or TDF for a period related to the risk for HBV reinfection: 1. low-risk patients (HBeAg-negative and HBV DNA < 12 IU/mL before LT) were due to withdraw from HBIg once HBsAg had become negative after a minimum of 7 days of HBIg+NA; 2. high-risk patients were due to receive HBIg for at least 6 months, after which they continued with third-generation NA monotherapy, only.

RESULTS

Twenty patients with a median interquartile range (IQR) follow-up of 46 (64-39) months were enrolled in the study (40% receiving ETV, 60% receiving TDF). Two low-risk patients refused early HBIg withdrawal and were therefore treated and analyzed along with the high-risk group. Eventually, there were 2 groups: group A, which included 12 low-risk patients, and group B, which included 8 patients (six high-risk, 2 low-risk). After transplantation, group A and B patients received HBIg+NA for a median (IQR) time of 7 (9-7) days and 9 (13-5) months, respectively. All 20 recipients demonstrated HBV DNA < 12 IU/mL and stable graft function during follow-up. Two patients (10%), 1 from each group, had HBsAg relapse. Notably, both patients who relapsed had hepatocellular carcinoma (HCC) diagnosed before LT and showed very low levels (< 0.25 IU/mL) of HBsAg after recurrence.

CONCLUSION

In low-risk HBsAg-positive recipients, HBIg may be safely discontinued within 2 weeks of LT and replaced by ETV or TDF monotherapy.

Applicability, safety, and biological activity of regulatory T cell therapy in liver transplantation

Regulatory T cells (Tregs) are a lymphocyte subset with intrinsic immunosuppressive properties that can be expanded in large numbers ex vivo and have been shown to prevent allograft rejection and promote tolerance in animal models. To investigate the safety, applicability, and biological activity of autologous Treg adoptive transfer in humans, we conducted an open-label, dose-escalation, Phase I clinical trial in liver transplantation. Patients were enrolled while awaiting liver transplantation or 6-12 months posttransplant. Circulating Tregs were isolated from blood or leukapheresis, expanded under good manufacturing practices (GMP) conditions, and administered intravenously at either 0.5-1 million Tregs/kg or 3-4.5 million Tregs/kg. The primary endpoint was the rate of dose- limiting toxicities occurring within 4 weeks of infusion. The applicability of the clinical protocol was poor unless patient recruitment was deferred until 6-12 months posttransplant. Thus, only 3 of the 17 patients who consented while awaiting liver transplantation were dosed. In contrast, all six patients who consented 6-12 months posttransplant received the cell infusion. Treg transfer was safe, transiently increased the pool of circulating Tregs and reduced anti-donor T cell responses. Our study opens the door to employing Treg immunotherapy to facilitate the reduction or complete discontinuation of immunosuppression following liver transplantation.

Entecavir or tenofovir monotherapy prevents HBV recurrence in liver transplant recipients: A 5-year follow-up study after hepatitis B immunoglobulin withdrawal

BACKGROUND

Recent data suggest that oral third-generation nucleos(t)ide analogs (NA) monoprophylaxis following hepatitis B immunoglobulin (HBIg) withdrawal may be effective to prevent HBV reinfection after liver transplantation (LT).

PATIENTS AND METHODS

Between 01/2010 and 03/2012, all HBV monoinfected and HBV/HDV co-infected LT patients followed in our centre withdrew HBIg ± NA and were commenced on either ETV or TDF as monotherapy.

RESULTS

Seventy-seven patients were included in the study (55% TDF, 45% ETV). Group A comprised 69 HBV monoinfected patients and Group B 8 HBV/HDV co-infected patients. After HBIg withdrawal, Groups A and B patients were followed for 69 (range 13-83) months and 61 (range 31-78) months, respectively. No Group B patients had HBsAg or HBV DNA recurrence, while 6 (9%) Group A patients became HBsAg-positive after a median of 18 (range 1-40) months. The cumulative 5-year incidence of HBsAg recurrence was 9%. All 6 patients demonstrated undetectable HBV-DNA levels and stable graft function during 30 months of additional follow-up. In 3/6 patients, seroconversion was transitory, while the remaining 3 showed HBsAg levels <0.13 IU/mL over the entire period of observation. Pre-LT HCC emerged as the strongest predictor of HBsAg recurrence.

CONCLUSION

HBIG can be safely discontinued in HBsAgpositive LT recipients and replaced by ETV or TDF monotherapy.

Multiparametric Analysis of Circulating Exosomes and Other Small Extracellular Vesicles by Advanced Imaging Flow Cytometry

Extracellular vesicles (EVs) are responsible for a multitude of physiological functions, including immunomodulation. A heterogenous mixture of small EV (sEV) subsets, including putative exosomes, is derived when commonly used "exosome" isolation techniques are employed. Subset diversity relates in part to their different intracellular origins, and can be associated with distinct functional properties. Recent progress in the EV field has enabled the categorization of such subsets based on their surface composition. For the first time, we combine such emerging subset-specific markers with advanced imaging flow cytometry (iFCM) to perform high-throughput, multiparametric, vesicle-by-vesicle characterization, and functional assessment of specific small EV subsets, and exosomes in particular. The approach allows researchers to address three important applications. First, it is known that different isolation techniques result in the divergent recovery of particular vesicle subsets. Taking three commonly used "exosome" isolation techniques as test cases (ultracentrifugation, size-exclusion chromatography, and polymer-based precipitation), the capacity for convenient and accurate isolate compositional analysis by iFCM is demonstrated. The approach was able to corroborate and to quantify the known skewing of subtype recovery among different isolation approaches. Second, exosomes are a particularly widely studied EV subset. Applying exosome-specific markers to samples collected from an optimal clinical transplantation model, we verify the capacity for iFCM to detect exosomes in circulation, to establish their tissue of origin, and to provide insights as to their functional immunological potential. Finally, we describe a technique for establishing whether the transfer of a molecule of interest to a target cell is exosomally mediated. In so doing, we highlight the approach's utility in assessing the functional impact of circulating exosomes and in identifying their targets. In conclusion, we set out a new methodological approach by which small extracellular vesicle subsets, exosomes in particular, can be conveniently and comprehensively investigated, thereby offering novel phenotypic and functional insights.

IL-2 therapy restores regulatory T-cell dysfunction induced by calcineurin inhibitors

CD4+CD25+FOXP3+ Tregs constitute a heterogeneous lymphocyte subpopulation essential for curtailing effector T cells and establishing peripheral tolerance. Calcineurin inhibitors (CNIs) are among the most effective agents in controlling effector T-cell responses in humans. However, CNIs also reduce the size of the Treg pool. The functional consequences of this negative effect and the mechanisms responsible remain to be elucidated. We report here that CNIs compromise the overall Treg immunoregulatory capacity to a greater extent than would be predicted by the reduction in the size of the Treg compartment, given that they selectively promote the apoptosis of the resting and activated Treg subsets that are known to display the most powerful suppressive function. These effects are caused by reduced access to IL-2, because Tregs remain capable of translocating NFAT even in the presence of high CNI levels. Exogenous IL-2 restores the phenotypic changes and overall gene-expression effects exerted by CNIs and can even promote Treg expansion by enhancing antiapoptotic Bcl-2 expression. In a skin transplant model, the addition of IL-2 synergizes with CNIs treatment, promoting intragraft accumulation of Tregs and prolonged allograft survival. Hence, the combination of IL-2 and CNIs constitutes an optimal immunomodulatory regimen that enhances the pool of suppressive Treg subsets while effectively controlling cytopathic T cells.

Successful expansion of functional and stable regulatory T cells for immunotherapy in liver transplantation

Strategies to prevent organ transplant rejection whilst minimizing long-term immunosuppression are currently under intense investigation with regulatory T cells (Tregs) nearing clinical application. The clinical trial, ThRIL, recently commenced at King's College London, proposes to use Treg cell therapy to induce tolerance in liver transplant recipients, the success of which has the potential to revolutionize the management of these patients and enable a future of drug-free transplants. This is the first report of the manufacture of clinical grade Tregs from prospective liver transplant recipients via a CliniMACS-based GMP isolation technique and expanded using anti-CD3/CD28 beads, IL-2 and rapamycin. We report the enrichment of a pure, stable population of Tregs (>95% CD4(+)CD25(+)FOXP3(+)), reaching adequate numbers for their clinical application. Our protocol proved successful in, influencing the expansion of superior functional Tregs, as compared to freshly isolated cells, whilst also preventing their conversion to Th17 cells under pro-inflammatory conditions. We conclude with the manufacture of the final Treg product in the clinical research facility (CRF), a prerequisite for the clinical application of these cells. The data presented in this manuscript together with the much-anticipated clinical results from ThRIL, will undoubtedly inform the improved management of the liver transplant recipient.

The straight to test endoscopy service for suspected colorectal cancer: meeting national targets but are we meeting our patients' expectations?

AIM

The NHS Cancer Plan describes initiatives to improve patient care in the UK, including the two-week rule cancer referral pathway. To meet this target a straight to test (STT) endoscopy service was devised to expedite diagnosis of suspected colorectal cancer. Our novel study aimed to determine patient satisfaction with this new approach to rapid access investigation.

METHOD

An anonymized questionnaire was posted to 300 patients who had undergone STT endoscopy in our unit between January and June 2010. It assessed satisfaction with the service overall, time from referral to investigation, pre-test information, bowel preparation instructions and time to results as well as preference for a traditional pre-test or post-test outpatient appointment and awareness that the referral was for suspected bowel cancer.

RESULTS

In all, 174 questionnaires were obtained (58% yield; mean age 68.8; 44.8% men). 82.2% of patients were 'very satisfied' with the service overall, 82.8% with time from referral to test, 75.2% with time from test to results, 73% with endoscopy information and 69.5% with bowel preparation instructions. Eight per cent would rather have seen a specialist prior to endoscopy, 31.6% would have preferred a post-test appointment and 68.4% of patients were aware that referral was for suspected bowel cancer.

CONCLUSION

Straight to test is popular with patients. It offers a fast and cost effective service in the diagnosis of colorectal cancer and meets national targets whilst reducing the volume burden on outpatient clinics. However, its success heavily relies on accurate communication between general practitioner, patient and secondary care.

Prospective multicenter clinical trial of immunosuppressive drug withdrawal in stable adult liver transplant recipients

Lifelong immunosuppression increases morbidity and mortality in liver transplantation. Discontinuation of immunosuppressive drugs could lessen this burden, but the safety, applicability, and clinical outcomes of this strategy need to be carefully defined. We enrolled 102 stable liver recipients at least 3 years after transplantation in a single-arm multicenter immunosuppression withdrawal trial. Drugs were gradually discontinued over a 6 to 9-month period. The primary endpoint was the development of operational tolerance, defined as successful immunosuppressive drug cessation maintained for at least 12 months with stable graft function and no histopathologic evidence of rejection. Out of the 98 recipients evaluated, 57 rejected and 41 successfully discontinued all immunosuppressive drugs. In nontolerant recipients rejection episodes were mild and resolved over 5.6 months (two nontolerant patients still exhibited mild gradually improving cholestasis at the end of follow-up). In tolerant recipients no progressive clinically significant histological damage was apparent in follow-up protocol biopsies performed up to 3 years following drug withdrawal. Tolerance was independently associated with time since transplantation (odds ratio [OR] 1.353; P = 0.0001), recipient age (OR 1.073; P = 0.009), and male gender (OR 4.657; P = 0.016). A predictive model incorporating the first two clinical variables identified subgroups of recipients with very high (79%), intermediate (30%-38%), and very low (0%) likelihood of successful withdrawal.

CONCLUSION

When conducted at late timepoints after transplantation, immunosuppression withdrawal is successful in a high proportion of carefully selected liver recipients. A combination of clinical parameters could be useful to predict the success of this strategy. Additional prospective studies are now needed to confirm these results and to validate clinically applicable diagnostic biomarkers.

The UK national study of magnetic resonance imaging as a method of screening for breast cancer (MARIBS)

The UK national study of magnetic resonance imaging as a method of screening for breast cancer (MARIBS) is in progress. The study design, accrual to date, and related research projects are described. Revised accrual rates and expected recruitment are given. 15 cancers have been detected to date, from a total of 1236 screening measurements. This event rate and the tumour grades reported are compared with recent reports from other studies in women at high risk of breast cancer.

Proton magnetic resonance spectroscopy and morphometry of the hippocampus in chronic fatigue syndrome

Seven patients with chronic fatigue syndrome (CFS) were matched with ten healthy control subjects of similar age. Hippocampal volume, obtained from magnetic resonance images using an unbiased method, showed no difference between the two groups, whereas proton magnetic resonance spectroscopy showed a significantly reduced concentration of N-acetylaspartate in the right hippocampus of CFS patients (p = 0.005).

Brimonidine and postoperative pressure spikes in cataract surgery

PURPOSE

To evaluate the efficacy of brimonidine in controlling postoperative pressure spikes following clear corneal cataract outpatient day surgery, in private practice in Australia.

METHODS

A prospective randomized trial was performed on 123 patients. Brimonidine 0.2% was instilled in the eyes 15 min prior to surgery, and intraocular pressure was checked 6 hours postoperatively.

RESULTS

Mean postoperative intraocular pressures at 6 hours were 30.33 mmHg in the treated group and 30.76 mmHg in the control group.

CONCLUSION

Brimonidine 0.2% instilled preoperatively offered no significant reduction in postoperative intraocular pressure spikes.

Effect of lens style on postoperative refractive astigmatism after small incision cataract surgery

PURPOSE

To evaluate the astigmatic results of two popular foldable intraocular lenses when standard surgical approaches are used in rural private practice in Australia.

METHODS

Four hundred consecutive cataract operations were followed in a prospective study. The refractive results of patients receiving the Alcon Acrysof MA30 lens were compared to those receiving the Allergan silicone S140 lens. All patients were over 60 years of age and had no intercurrent ocular disease. Refractive and keratometric astigmatism was analysed both by vector analysis and as an absolute measure.

RESULTS AND CONCLUSION

The Acrysof lens is associated with less postoperative astigmatism (P = 0.01), than the Silicone S140 lenses.

The pathology of the lower leg muscles in pure forefoot pes cavus

Enlargement of the peroneus longus muscle is a common occurrence in patients with forefoot pes cavus, and may contribute to the cavus deformity. The present study compares the morphology of up to five lower leg muscles from 17 patients with forefoot pes cavus with those of normal muscles. Eight cases had an identifiable neurogenic cause for the cavus. In four cases of hereditary motor-sensory neuropathy, the tibialis anterior showed more severe damage than the peroneus longus. In two cases of cerebral palsy, fibre atrophy and increased oxidative enzyme activity were observed. In nine clinically idiopathic cases, the histological appearances ranged from normal to generalised fibre atrophy or hypertrophy in individual muscles. There was a trend for the mean fibre area to be greater in peroneus longus than in tibialis anterior in six of the idiopathic group of patients. The muscle cross-sectional area on magnetic resonance imaging was correlated closely with the mean fibre area measured on tissue sections. In idiopathic forefoot pes cavus, fibre hypertrophy in peroneus longus (relative to tibialis anterior) may contribute to the cavus deformity. Muscle fibre hyperplasia may contribute to the peroneal muscle enlargement in Friedreich's ataxia. In none of the cases was peroneus longus enlargement due to fat or fibrous tissue replacement.

Refractive keratoplasty for post-graft astigmatism

Refractive keratoplasty using modified relaxing incisions with compression sutures was performed on 33 patients with high post-keratoplasty astigmatism. The mean reduction in keratometric astigmatism was 8.38 dioptres from a preoperative mean of 12.21 dioptres (SD, 3.59) to 3.93 dioptres (SD, 2.13). All patients noted a marked functional improvement. Two patients required reoperation. One patient required resuturing. Our modification of undercutting the relaxing incisions greatly increases the range of astigmatism that can be treated with this technique.

Corneal biopsy in microbial keratitis

Presumed microbial keratitis in the absence of a specific microbiological diagnosis is a particularly difficult clinical problem. Corneal biopsy may provide the diagnosis when corneal scrapings have been negative. We present two cases in which corneal biopsy was helpful and discuss the role of corneal biopsy in the management of chronic keratitis.

A comparison between iotrolan, a non-ionic dimer, and a hyperosmolar contrast medium, Urografin, in hysterosalpingography

For hysterosalpingography, there were no significant differences between the non-ionic dimeric contrast medium iotrolan (300 mgI/%) and Urografin (370 mgI/%) with regard to ease of application or radiographic quality, and both agents were equally suitable. There were no significant differences between two groups of patients with regard to pain due to instrumentation, pain at the time of injection and pain up to 2 h after the procedure. There was a significant difference (p = 0.04) between the two groups with respect to delayed pain, when iotrolan was associated with a lower incidence and decreased severity of delayed pain. There were no differences in the incidence of nausea, vomiting, headache and syncope. No allergic phenomena were seen in either group.

Subjective experiences of magnetic resonance imaging

Clinical experience with the new technology of magnetic resonance imaging (MRI) has indicated that the procedure may produce anxiety in a number of patients, to the extent that occasionally a patient may be unwilling to undergo the procedure. A study of patients' subjective experiences of MRI was therefore conducted and these were compared with those of patients undergoing computed tomography (CT). Initial interviews with 15 MRI and 15 CT patients led to the development of a questionnaire which was administered to a further 40 patients in each setting. No significant differences were found between those factors identified as unpleasant in MRI and those of CT, with the exception of the confined space of MRI; 40% of the MRI patients found this unpleasant by comparison with only 15% of the CT patients. Principal components analysis of the concerns expressed suggested three factors, to do with the machine itself, the environment of the machine, and the social interactions involved. Patients finding the procedures unpleasant tended to be those with high initial levels of anxiety, little experience of diagnostic procedures, and believing themselves to have cancer.