Infections after orthotopic liver transplantation

Impact of Hepatoblastoma on Infectious Complications Following Pediatric Liver Transplantation

BACKGROUND

Liver transplantation is the standard therapy for end-stage liver disease in pediatric patients with biliary atresia (BA), congenital and metabolic conditions, and for an unresectable malignant tumor like hepatoblastoma (HB). BA is the leading indication for pediatric liver transplantation, while HB is the most common childhood liver cancer. Despite improved outcomes through advanced surgical techniques and novel immunosuppression, pediatric liver transplantation (pLT) is complicated by post-transplant infections.

METHODS

A retrospective review was performed of pLT recipients at Cincinnati Children's Hospital Medical Center (CCHMC) and stratified patients by underlying disease to assess impact on post-transplant infectious events.

RESULTS

BA patients were youngest at pLT (12.5 months; p < 0.001) compared to other disease cohorts (HB 30.8, other 43.7). All HB patients received organs from deceased donors. In the year following pLT, 93% of the patients experienced at least one infectious event (IE). HB patients had the highest mean number of IE across disease groups (5.5 IE/patient vs. BA 4.5, other 4.0; p = 0.055), with significantly more patients with fever and neutropenia (p < 0.001) and EBV infections (p = 0.012). HB patients were more likely to develop IE earlier after pLT than non-HB groups (p = 0.013), especially Clostridioides difficile (p < 0.01) and fever and neutropenia (p < 0.01). Despite having variable IE experiences, 1-and-5-year survival across disease groups were similar.

CONCLUSIONS

IE were frequently observed in HB patients after pLT, possibly related to pre-and-postoperative chemotherapy and associated neutropenia. Underlying disease may help inform targeted infection-related patient management following pLT.

Algorithmic Approach to Deranged Liver Functions After Transplantation

Liver transplant (LT) recipients require close follow-up with regular monitoring of the liver function tests (LFTs). Evaluation of deranged LFT should be individualized depending upon the time since LT, peri-operative events, clinical course, and any complications. These derangements can range from mild and asymptomatic to severe and symptomatic elevations requiring expedited personalized assessment and management. Pattern of LFT derangement (hepatocellular, cholestatic, or mixed), donor-recipient risk factors, timing after LT (post-operative, 1-12 months, and >12 months since LT) along with clinical context and symptomatology are important considerations before proceeding with the initial evaluation. Compliance to immunosuppression and drug interactions should be ascertained along with local epidemiology of infections. Essential initial evaluation must include an ultrasound abdomen with Doppler to rule out any structural causes such as biliary or vascular complications apart from focussed laboratory evaluation. Early allograft dysfunction, ischemia reperfusion injury, small-for-size syndrome, biliary leaks, hepatic artery, and portal vein thrombosis are usual culprits in the early post-operative period whereas viral hepatitis (acute or reactivation), opportunistic infections, and recurrence of the primary disease are more frequent in the later period. Graft rejection, biliary strictures, sepsis, and drug induced liver injury remain possible etiologies at all times points after LT. Initial evaluation algorithm must be customized based on history, clinical examination, risk factors, and pattern and severity of deranged LFT. Allograft rejection is a diagnosis of exclusion and requires liver biopsy to confirm and assess severity. Empirical treatment of rejection sans liver biopsy is discouraged.

Immunomonitoring via ELISPOT Assay Reveals Attenuated T-Cell Immunity to CMV in Immunocompromised Liver-Transplant Patients

Assessing immune responses to cytomegalovirus (CMV) after liver transplant in patients on immunosuppressive therapy remains challenging. In this study, employing ELISPOT assays, 52 liver-transplant recipients were evaluated for antiviral T-cell activity in peripheral blood mononuclear cells (PBMCs), measuring interferon-γ (IFN-γ) secretion upon stimulation with CMV-specific peptides (CMV peptide pool, CMV IE-1, and pp65 antigens). Parameters such as stimulation index, mean spot size, and mean spot count were measured. The study found that heightened immunosuppression, especially with prednisolone in triple therapy, significantly dampened CMV-specific immune responses. This was demonstrated by decreased IFN-γ production by CMV-specific T-cells (CMV peptide pool: p = 0.036; OR = 0.065 [95% CI: 0.005-0.840], pp65 antigen: p = 0.026; OR = 0.048 [95% CI: 0.003-0.699]). Increased immunosuppression correlated with reduced IFN-γ secretion per cell, reflected in smaller mean spot sizes for the CMV peptide pool (p = 0.019). Notably, shorter post-transplant intervals correlated with diminished antiviral T-cell IFN-γ release at two years (CMV peptide pool: p = 0.019; IE antigen: p = 0.010) and five years (CMV peptide pool: p = 0.0001; IE antigen: p = 0.002; pp65 antigen: p = 0.047), as did advancing age (pp65 antigen: p = 0.016, OR = 0.932, 95% CI: 0.881-0.987). Patients with undetectable CMV antigens had a notably higher risk of CMV reactivation within six months from blood collection, closely linked with triple immunosuppression and prednisolone use. These findings highlight the intricate interplay between immunosuppression, immune response dynamics, and CMV reactivation risk, emphasizing the necessity for tailored immunosuppressive strategies to mitigate CMV reactivation in liver-transplant recipients. It can be concluded that, particularly in the early months post-transplantation, the use of prednisolone as a third immunosuppressant should be critically reconsidered. Additionally, the use of prophylactic antiviral therapy effective against CMV in this context holds significant importance.

Long Term Complications of Immunosuppression Post Liver Transplant

Improvement in immunosuppression has led to a remarkable improvement in short-term and long-term outcomes post-liver transplant (LT). However, with improvements in long-term survival, complications related to immunosuppressive drugs, either directly or indirectly, have also increased. The adverse events could be drug-specific, class-specific, or generic. Calcineurin inhibitors (cyclosporine and tacrolimus) are the backbone of the immunosuppression after LT and the main culprit associated with most of the complications, including renal failure, post-transplant diabetes mellitus (PTDM), and metabolic syndrome. Steroids are also implicated in the development of diabetes, osteoporosis, and metabolic syndrome post-LT. The development of infections and de novo malignancies (DNMs) is a generic effect linked to the overall cumulative immunosuppression. The development of these complications significantly hampers the quality of life and leads to increased morbidity and mortality post-LT. Thus, it is important to minimize the cumulative immunosuppression dose while simultaneously preventing allograft rejection. This review provides up-to-date, comprehensive knowledge of the complications of long-term immunosuppression post-LT along with associated risk factors and strategies to minimize the risk of complications.

Pretransplant Renal Dysfunction Negatively Affects Prognosis After Living Donor Liver Transplantation: A Single-Center Retrospective Study

BACKGROUND

To evaluate the influence of preoperative renal function on prognosis after living donor liver transplantation (LDLT).

METHODS

Living donor liver transplantation cases were categorized into 3 groups as follows: renal failure with hemodialysis (HD; n = 42), renal dysfunction (RD; n = 94) (glomerular filtration rate <60 mL/min/1.73 m2), and normal renal function (NF; n = 421). The study used no prisoners, and participants were neither coerced nor paid. The manuscript complies with the Helsinki Congress and the Declaration of Istanbul.

RESULTS

Five-year overall survival (OS) rates were 59.0%, 69.3%, and 80.0% in the HD, RD, and NF groups, respectively (P < .01). The frequency of bacteremia within 90 days after LDLT was 76.2%, 37.2%, and 34.7%, respectively (P < .01 in HD vs RD and HD vs NF). Patients with bacteremia showed a worse outcome than those without (1-year OS, 65.6% vs 93.3%), thus corroborating the poor prognosis in the HD group. The high frequency of bacteremia in the HD group was mainly attributable to health care-associated bacterium, such as coagulase-negative Staphylococci, Enterococcus spp., and Pseudomonas aeruginosa. In the HD group, HD was started within 50 days before LDLT for acute renal failure in 35 patients, of which 29 (82.9%) successfully withdrew from HD after LDLT and demonstrated better prognosis (1-year OS, 69.0% vs 16.7%) than those who continued HD.

CONCLUSIONS

Preoperative renal dysfunction is associated with poor prognosis after LDLT, possibly due to a high incidence of health care-associated bacteremia.

Machine Learning Model Validated to Predict Outcomes of Liver Transplantation Recipients with Hepatitis C: The Romanian National Transplant Agency Cohort Experience

BACKGROUND AND OBJECTIVES

In the early period after liver transplantation, patients are exposed to a high rate of complications and several scores are currently available to predict adverse postoperative outcomes. However, an ideal, universally accepted and validated score to predict adverse events in liver transplant recipients with hepatitis C is lacking. Therefore, we aimed to establish and validate a machine learning (ML) model to predict short-term outcomes of hepatitis C patients who underwent liver transplantation.

MATERIALS AND METHODS

We conducted a retrospective observational two-center cohort study involving hepatitis C patients who underwent liver transplantation. Based on clinical and laboratory parameters, the dataset was used to train a deep-learning model for predicting short-term postoperative complications (within one month following liver transplantation). Adverse events prediction in the postoperative setting was the primary study outcome.

RESULTS

A total of 90 liver transplant recipients with hepatitis C were enrolled in the present study, 80 patients in the training cohort and ten in the validation cohort, respectively. The age range of the participants was 12-68 years, 51 (56,7%) were male, and 39 (43.3%) were female. Throughout the 85 training epochs, the model achieved a very good performance, with the accuracy ranging between 99.76% and 100%. After testing the model on the validation set, the deep-learning classifier confirmed the performance in predicting postoperative complications, achieving an accuracy of 100% on unseen data.

CONCLUSIONS

We successfully developed a ML model to predict postoperative complications following liver transplantation in hepatitis C patients. The model demonstrated an excellent performance for accurate adverse event prediction. Consequently, the present study constitutes the foundation for careful and non-invasive identification of high-risk patients who might benefit from a more intensive postoperative monitoring strategy.

Fibrinolysis resistance after liver transplant as a predictor of early infection

BACKGROUND

Infection is a leading cause of morbidity in liver transplant (LT). Considering that the fibrinolytic system is altered in sepsis, we investigated the relationship between fibrinolysis resistance (FR) and post-transplant infection.

METHODS

Fibrinolysis was quantified using thrombelastography (TEG) with the addition of tPA to quantify FR. FR was defined as LY30 = 0% and stratified as transient if present on POD1 or POD5 (tFR), persistent (pFR) if present on both, or no FR (nFR) if absent.

RESULTS

180 LT recipients were prospectively enrolled. 52 (29%) recipients developed infection. 72 had tFR; 37 had pFR; and 71 had nFR. Recipients with pFR had significantly greater incidence of infections (51% vs. 26% tFR vs. 20% nFR, p = 0.002). pFR was independently associated with increased odds of post-transplant infection (adjusted OR 3.39, p = 0.009).

CONCLUSIONS

Persistent fibrinolysis resistance is associated with increased risk of post-transplant infection.

Galectin-3 is overexpressed in advanced cirrhosis and predicts post-liver transplant infectious complications

BACKGROUND & AIMS

Patients with advanced cirrhosis often have immune dysfunction and are more susceptible to infections. Galectin-3 is a β-galactoside-binding lectin implicated in inflammation, immune regulation and liver fibrosis. We aim to investigate galectin-3 expression in advanced cirrhosis and its ability to predict post-transplant infectious complications.

METHODS

We collected sera and liver samples from 129 cirrhotic patients at the time of liver transplantation and from an external cohort of 37 patients with alcoholic liver disease including alcoholic hepatitis (AH) at the time of diagnosis. Galectin-3 was assessed by ELISA, real-time PCR, immunohistochemistry and RNA-seq. Receiver operating characteristic curves and Cox proportional-hazards regression analysis were performed to assess the predictive power of galectin-3 for disease severity and post-transplant infections.

RESULTS

Increased galectin-3 levels were found in advanced cirrhosis. Galectin-3 significantly correlated with disease severity parameters and inflammatory markers. Galectin-3 had significant discriminating power for compensated and advanced cirrhosis (AUC = 0.78/0.84, circulating/liver galectin-3; p < .01), and was even higher to discriminate severe AH (AUC = 0.95, p < .0001). Cox Proportional-hazard model showed that galectin-3, MELD-Na and the presence of SIRS predict the development of post-transplant infectious complications. Patients with circulating galectin-3 (>16.58 ng/ml) were at 2.19-fold 95% CI (1.12-4.29) increased risk, but when combined with MELD-Na > 20.0 and SIRS, the risk to develop post-transplant infectious complications, increased to 4.60, 95% CI (2.38-8.90).

CONCLUSION

Galectin-3 is a novel biological marker of active inflammation and disease severity that could be clinically useful alone or in combination with other scores to discriminate advanced cirrhosis and predict post-transplant infectious complications.

An Essential Guide for Managing Post-Liver Transplant Patients: What Primary Care Physicians Should Know

With long-term survival after liver transplantation becoming the rule, care for medical problems arising over time in liver-transplanted patients gained increasing importance. The most common causes of death occurring more than 1 year after liver transplantation are unrelated to liver diseases and facilitated by immunosuppressive treatments; examples are malignancies, renal failure, and cardiovascular, metabolic, and infectious diseases. Recipients receive life-long follow-up care at transplant centers, however, the increasing number of liver-transplanted patients is saturating the health care supply that transplant centers have to offer. Primary care physicians are increasingly exposed to liver-transplanted patients, even in the early periods after transplant, and an understanding of the most common risks and complications faced by these patients would enhance their care. This article reviews the long-term care of liver transplant recipients, emphasizing the key internal medicine-related issues that should be known by primary care physicians. A specific section is devoted to implementing strategies to involve these physicians in the long-term follow-up of liver-transplanted patients in close collaboration with transplant hepatologists.

Recurrence of Primary Sclerosing Cholangitis After Liver Transplant in Children: An International Observational Study

BACKGROUND AND AIMS

Recurrent primary sclerosing cholangitis (rPSC) following liver transplant (LT) has a negative impact on graft and patient survival; little is known about risk factors for rPSC or disease course in children.

APPROACH AND RESULTS

We retrospectively evaluated risk factors for rPSC in 140 children from the Pediatric PSC Consortium, a multicenter international registry. Recipients underwent LT for PSC and had >90 days of follow-up. The primary outcome, rPSC, was defined using Graziadei criteria. Median follow-up after LT was 3 years (interquartile range 1.1-6.1). rPSC occurred in 36 children, representing 10% and 27% of the subjects at 2 years and 5 years following LT, respectively. Subjects with rPSC were younger at LT (12.9 vs. 16.2 years), had faster progression from PSC diagnosis to LT (2.5 vs. 4.1 years), and had higher alanine aminotransferase (112 vs. 66 IU/L) at LT (all P < 0.01). Inflammatory bowel disease was more prevalent in the rPSC group (86% vs. 66%; P = 0.025). After LT, rPSC subjects had more episodes of biopsy-proved acute rejection (mean 3 vs. 1; P < 0.001), and higher prevalence of steroid-refractory rejection (41% vs. 20%; P = 0.04). In those with rPSC, 43% developed complications of portal hypertension, were relisted for LT, or died within 2 years of the diagnosis. Mortality was higher in the rPSC group (11.1% vs. 2.9%; P = 0.05).

CONCLUSIONS

The incidence of rPSC in this cohort was higher than previously reported, and was associated with increased morbidity and mortality. Patients with rPSC appeared to have a more aggressive, immune-reactive phenotype. These findings underscore the need to understand the immune mechanisms of rPSC, to lay the foundation for developing new therapies and improve outcomes in this challenging population.

Artificial Intelligence May Predict Early Sepsis After Liver Transplantation

Background: Sepsis, post-liver transplantation, is a frequent challenge that impacts patient outcomes. We aimed to develop an artificial intelligence method to predict the onset of post-operative sepsis earlier. Methods: This pilot study aimed to identify "physiomarkers" in continuous minute-by-minute physiologic data streams, such as heart rate, respiratory rate, oxygen saturation (SpO2), and blood pressure, to predict the onset of sepsis. The model was derived from a cohort of 5,748 transplant and non-transplant patients across intensive care units (ICUs) over 36 months, with 92 post-liver transplant patients who developed sepsis. Results: Using an alert timestamp generated with the Third International Consensus Definition of Sepsis (Sepsis-3) definition as a reference point, we studied up to 24 h of continuous physiologic data prior to the event, totaling to 8.35 million data points. One hundred fifty-five features were generated using signal processing and statistical methods. Feature selection identified 52 highly ranked features, many of which included blood pressures. An eXtreme Gradient Boost (XGB) classifier was then trained on the ranked features by 5-fold cross validation on all patients (n = 5,748). We identified that the average sensitivity, specificity, positive predictive value (PPV), and area under the receiver-operator curve (AUC) of the model after 100 iterations was 0.94 ± 0.02, 0.9 ± 0.02, 0.89 ± 0.01, respectively, and 0.97 ± 0.01 for predicting sepsis 12 h before meeting criteria. Conclusion: The data suggest that machine learning/deep learning can be applied to continuous streaming data in the transplant ICU to monitor patients and possibly predict sepsis.

Oral diseases after liver transplantation: a systematic review and meta-analysis

Objective To conduct a systematic review and meta-analysis to evaluate the impact of liver transplantation on the occurrence and frequency of oral diseases in humans.Data sources The study query was performed on Medline/PubMed, Ovid, Cochrane Library and Embase databases, including the grey literature.Data selection Observational studies comparing the frequency of oral manifestations in post-liver transplantation patients versus reference population were eligible for inclusion.Data extraction and analysis The article selection, data extraction and quality assessment were executed by three independent investigators. A random-effects meta-analysis was carried out for computation of relative risks of oral malignancies (standardised incidence ratio [SIR] and 95% confidence interval [CI]).Data synthesis Among 248 studies identified, 11 met the eligibility criteria and six were included in the meta-analysis. Opportunistic fungal infections (Candida spp.) and lesions with malignant potential were reported to be more frequently prevalent after liver transplantation. Calculations indicated that after liver transplantation, the patients have a fivefold increased risk for oral cancer occurrence compared to the general population (SIR = 5.006; 95% CI 2.803 to 8.94; p <0.001).Conclusions The findings suggest that liver transplantation increases the risk of oral malignancies and the frequency of other mucosal lesions.

The Role of Autophagy in Murine Cytomegalovirus Hepatitis

Autophagy is involved in the pathogenesis of multiple pathogen infection. Previous studies have reported that human cytomegalovirus (CMV) activates autophagy in the early stage of infection and then inhibits autophagy. Little is known about the role of autophagy in murine CMV (MCMV) infection, especially in MCMV-induced hepatitis. The purpose of this study is to investigate the role of autophagy in MCMV hepatitis. BALB/c mice were infected with MCMV and a series of experiments involving western blot, immunofluorescence, immunohistochemistry, H&E (Hematoxylin and Eosin) staining and quantitative real-time polymerase chain reaction were performed in this study. The expression of SQSTM1/p62, PI3K, the ratio of phosphorylated Akt to total Akt, and the ratio of phosphorylated mammalian target of rapamycin (mTOR) to total mTOR were increased, and the expression of light-chain 3 (LC3)-II were decreased in the livers of infected mice on days 3 and 7 postinfection (p.i.). Compared with the untreated infected group, increased transcription level of MCMV glycoprotein B (gB), increased expression levels of interleukin1-β (IL-1β), aspartate aminotransferase (AST) and alanine aminotransferase (ALT), decreased expression level of type I interferon α (IFN-α), as well as aggravated liver pathological injury were detected in starvation-treated infected group on days 3 and 7 p.i.; whereas decreased transcription level of MCMV gB, decreased expression levels of IL-1β, AST and ALT, increased expression level of type I IFN-α, as well as alleviated liver pathological injury were detected in chloroquine (CQ)-treated infected group on day 3 p.i. In conclusion, autophagy is inhibited through activating the PI3K/Akt/mTOR pathway in the liver of BALB/c mice during MCMV infection, and autophagy may promote MCMV replication and aggravate liver pathological damage and inflammation. Further understanding of the interactions between autophagy and MCMV infection and its potential mechanism may bring new important cues to the control of MCMV infection and antiviral therapy.

Clinical Impacts and Outcomes With Possible Donor-Derived Infection in Infected Donor Liver Transplantation: A Single-Center Retrospective Study in China

BACKGROUND

Information on possible donor-derived transmission events in China is limited. We evaluated the impacts of liver transplantation from infected deceased-donors, analyzed possible donor-derived bacterial or fungal infection events in recipients, and evaluated the etiologic agents' characteristics and cases outcomes.

METHODS

A single-center observational study was performed from January 2015 to March 2017 to retrospectively collect data from deceased-donors diagnosed with infection. Clinical data were recorded for each culture-positive donor and the matched liver recipient. The microorganisms were isolated and identified, and antibiotic sensitivity testing was performed. The pathogens distribution and incidence of possible donor-derived infection (P-DDI) events were analyzed and evaluated.

RESULTS

Information from 211 donors was collected. Of these, 82 donors were infected and classified as the donation after brain death category. Overall, 149 and 138 pathogens were isolated from 82 infected donors and 82 matched liver recipients, respectively. Gram-positive bacteria, Gram-negative bacteria, and fungi accounted for 42.3% (63 of 149), 46.3% (69 of 149), and 11.4% (17 of 149) of pathogens in infected donors. The incidence of multidrug-resistant bacteria was high and Acinetobacter baumannii was the most concerning species. Infections occurred within the first 2 weeks after liver transplantation with an organ from an infected donor. Compared with the noninfection recipient group, the infection recipient group experienced a longer mechanical ventilation time (P = .004) and intensive care unit stay (P = .003), a higher incidence of renal dysfunction (P = .026) and renal replacement therapy (P = .001), and higher hospital mortality (P = .015). Possible donor-derived infection was observed in 14.6% of cases. Recipients with acute-on-chronic liver failure were more prone to have P-DDI than recipients with other diseases (P = .007; odds ratio = 0.114; 95% confidence interval, .025-.529).

CONCLUSIONS

When a liver recipient receives a graft from an infected deceased-donor, the postoperative incidence of infection is high and the infection interval is short. In addition, when a possible donor-derived, drug-resistant bacterial infection occurs, recipients may have serious complications and poor outcomes.

Interrelationship between Toll-like receptors and infection after orthotopic liver transplantation

Early microbial recognition by the innate immune system is accomplished by Toll-like receptors (TLRs), with resultant initiation of a pro-inflammatory response against infecting organisms. In spite of presence of an abundance of Toll-like receptors on the surface of the liver, gut bacteria does not elicit an inflammatory reaction in healthy individuals due to tolerance to these TLRs, suggesting that the inflammatory responses seen in the liver are the result of breakdown of this tolerance. While orthotopic liver transplantation is often life saving in many instances, death following this procedure is most commonly due to infection that occurs in up to 80% of transplant recipients, most commonly due to microbial causes in up to 70% of cases and viral infections in 20%, while fungal infections affect only 8% of cases. The probability of acquiring infection following hepatic transplantation is heightened due to affection of the innate immune defense mechanisms of the host following this procedure. Single nucleotide polymorphisms of TLRs have been associated with increased likelihood of either development of post-transplant infection or eradication of infecting organism. However, conflicting reports from other studies reveal that prevalence of this single nucleotide polymorphism is not increased in infected patients.

Stricturing CMV enteritis in an adult liver transplant recipient

Cytomegalovirus (CMV) is a common posttransplant infection, most commonly seen in settings of excessive immunosuppression. Before the advent of CMV specific antiviral therapies, the standard treatment approaches for CMV disease were immunosuppression reductions to let the transplant recipient mount an immunologic response against CMV. Additionally, CMV is rarely identified as causing stricturing enteritis and has not previously been reported as causing stricturing enteritis in an adult transplant recipient. All identified reports of stricturing CMV enteritis have been reported in either pediatric patient populations or those with severe immunosuppression from human immunodeficiency virus and acquired immune deficiency syndrome. Our report presents the unusual case of an adult liver transplant recipient many years after transplant and on minimal immunosuppression with mycophenolate alone who developed stricturing CMV enteritis.

Neurological Complications Occurring After Liver Transplantation: Role of Risk Factors, Hepatic Encephalopathy, and Acute (on Chronic) Brain Injury

Orthotopic liver transplantation (LT) remains the only way to definitively cure patients with the most severe liver diseases. Because the survival rate is now fairly high, important questions about neurological sequelae or quality of life after LT have emerged. Indeed, LT represents a peculiar situation because up to 30% of patients present with neurological symptoms after LT compared with only 4% after cardiac transplant and 0.5% after renal transplant. These postoperative neurological symptoms have long been interpreted as sequelae of hepatic encephalopathy (HE). However, postoperative decompensation of an unknown cerebral condition due to the pathophysiology of cirrhosis or undiagnosed neurodegenerative disorders or aging constitute other possibilities that are underrecognized. Some patients who undergo LT for acute liver failure and patients with cirrhosis without episodes of HE and without any previous cerebral alteration also display post-LT neurological symptoms. This latter situation speaks in favor of a direct adverse effect of either general anesthesia, the surgical procedure, or factors related to the postoperative intensive care unit (ICU) environment. The role of inflammation, which has been described in the ICU setting, could also be a crucial determinant. In this review, we will discuss the neurological complications associated with LT, the neurocognitive complications after LT, and how to assess the LT-related neurological or neurocognitive complications. Furthermore, we will review the various hypotheses surrounding post-LT neurocognitive impairment and will conclude with recommendations for future directions.

Infections in Liver Transplantation

Liver transplantation has become an important treatment modality for patients with end-stage liver disease/cirrhosis, acute liver failure, and hepatocellular carcinoma. Although surgical techniques and immunosuppressive regimens for liver transplantation have improved significantly over the past 20 years, infectious complications continue to contribute to the morbidity and mortality in this patient population. The use of standardized screening protocols for both donors and recipients, coupled with targeted prophylaxis against specific pathogens, has helped to mitigate the risk of infection in liver transplant recipients. Patients with chronic liver disease and cirrhosis have immunological deficits that place them at increased risk for infection while awaiting liver transplantation. The patient undergoing liver transplantation is prone to develop healthcare-acquired infections due to multidrug-resistant organisms that could potentially affect patient outcomes after transplantation. The complex nature of liver transplant surgery that involves multiple vascular and hepatobiliary anastomoses further increases the risk of infection after liver transplantation. During the early post-transplantation period, healthcare-acquired bacterial and fungal infections are the most common types of infection encountered in liver transplant recipients. The period of maximal immunosuppression that occurs at 1–6 months after transplantation can be complicated by opportunistic infections due to both primary infection and reactivation of latent infection. Severe community-acquired infections can complicate the course of liver transplantation beyond 12 months after transplant surgery. This chapter provides an overview of liver transplantation including indications, donor-recipient selection criteria, surgical procedures, and immunosuppressive therapies. A focus on infections in patients with chronic liver disease/cirrhosis and an overview of the specific infectious complications in liver transplant recipients are presented.

Iron: an essential nutrient for Aspergillus fumigatus and a fulcrum for pathogenesis

PURPOSE OF REVIEW

Aspergillus fumigatus is a ubiquitous saprophytic fungus that can cause life-threatening invasive aspergillosis in immunocompromised patients. Apart from the immune status of the host only a few characterized virulence factors have been identified. In this review, we describe the role of iron in the manifestation of A. fumigatus virulence.

RECENT FINDINGS

We gathered recent clinical evidence suggesting that tissue iron overload increases the risk of invasive aspergillosis occurrence. Furthermore, we summarize the mechanisms that A. fumigatus employs to achieve iron homeostasis and their importance in A. fumigatus proliferation in vitro. We describe two recent in-vivo models that clearly demonstrate the importance of iron in A. fumigatus growth and invasion.

SUMMARY

Based on these recent findings, therapy aimed at managing A. fumigatus iron homeostasis locally could make conditions more favorable to the host.

Cytomegalovirus infection in pediatric patients with hepatoblastoma after liver transplantation

No studies have examined CMV infection in pediatric patients with HB receiving LT. Here, we retrospectively analyzed the incidence of and risk factors for CMV infection in 24 pediatric patients with HB who underwent LT between 1997 and 2015. CMV infection was monitored by measuring expression of pp65 CMV antigen for up to 4 months post-LT. CMV infection, defined as detection of at least one pp65-positive leukocyte, was detected in nine (37.5%) patients who did not develop CMV disease. Nine (47.4%) of nineteen patients who received post-LT chemotherapy experienced CMV infection; however, no CMV infection was observed in the five patients who did not receive post-LT chemotherapy (P = 0.012). There were no significant differences in the incidence of CMV infection between patients with ACR (60.0%) and those without (21.4%, P = 0.092), or between CMV seropositive (55.6%) and seronegative patients (33.3%, P = 0.675). All nine patients with CMV infection did not experience CMV disease due to the use of preemptive antiviral therapy. Close monitoring of CMV infection is recommended for patients with HB, particularly those receiving post-LT chemotherapy. Preemptive antiviral therapy is feasible for prophylaxis of CMV disease.

[Spectrum of pathogens in postoperative complications of visceral surgery : The problem of multidrug resistance]

In general surgery the etiology of surgical site infections has not significantly changed over the last 30 years. Gram-positive bacteria, e.g. coagulase negative staphylococci (CNS), Staphylococcus aureus and Enterococcus spp. as well as Gram-negative bacteria, e.g. Escherichia coli, Enterobacter spp., Klebsiella spp. and Pseudomonas aeruginosa, are the most common findings. Although in general surgery 10% of the S. aureus causing postoperative wound infections were methicillin resistant (MRSA), no cases of multidrug-resistant Gram-negative (MRGN) bacteria were reported. Yeasts (particularly Candida spp.) are rarely the pathogen causing surgical site infections (≤3%) and concomitant risk factors are typical (e.g. diabetes, chemotherapy, immunosuppression and malnutrition). Viruses are rarely the cause of surgical site infections. Transmission can occur by HBV, HCV or HIV positive surgical staff or in organ transplantations and postoperative reactivation of persistent infections is possible (especially for HBV, HCV, CMV, EBV and HIV). The principles for prevention of surgical site infections are dealt with as consequences of preoperative colonization by MRSA, methicillin-sensitive S. aureus (MSSA) and MRGN and reviewed with respect to screening, perioperative antibiotic prophylaxis and decolonization. In nosocomial peritonitis, the selection of antibiotics should consider previous antibiotic treatment. A single intra-abdominal detection of Candida spp. usually does not require antimycotic treatment in postoperatively stable and immunocompetent patients but is recommended in severe community-acquired or nosocomial peritonitis. Viral infections can be avoided by screening of organ donors and serological surveillance of surgery personnel.

A simplified regimen of targeted antifungal prophylaxis in liver transplant recipients: A single-center experience

BACKGROUND

Invasive fungal infection (IFI) is a severe complication of liver transplantation burdened by high mortality. Guidelines recommend targeted rather than universal antifungal prophylaxis based on tiers of risk.

METHODS

We aimed to evaluate IFI incidence, risk factors, and outcome after implementation of a simplified two-tiered targeted prophylaxis regimen based on a single broad-spectrum antifungal drug (amphotericin B). Patients presenting 1 or more risk factors according to literature were administered prophylaxis. Prospectively collected data on all adult patients transplanted in Turin from January 2011 to December 2015 were reviewed.

RESULTS

Patients re-transplanted before postoperative day 7 were considered once, yielding a study cohort of 581 cases. Prophylaxis was administered to 299 (51.4%) patients; adherence to protocol was 94.1%. Sixteen patients developed 18 IFIs for an overall rate of 2.8%. All IFI cases were in targeted prophylaxis group; none of the non-prophylaxis group developed IFI. Most cases (81.3%) presented within 30 days after transplantation during prophylaxis; predominant pathogens were molds (94.4%). Only 1 case of candidemia was observed. One-year mortality in IFI patients was 33.3% vs 6.4% in patients without IFI (P = .001); IFI attributable mortality was 6.3%. At multivariate analysis, significant risk factors for IFI were renal replacement therapy (OR = 8.1) and re-operation (OR = 5.2).

CONCLUSIONS

The implementation of a simplified targeted prophylaxis regimen appeared to be safe and applicable and was associated with low IFI incidence and mortality. Association of IFI with re-operation and renal replacement therapy calls for further studies to identify optimal prophylaxis in this subset of patients.

Early infections in the intensive care unit after liver transplantation-etiology and risk factors: A single-center experience

BACKGROUND

Infectious complications represent one of the main causes of perioperative morbidity and mortality of liver transplant recipients. The primary objective of this retrospective observational study was to evaluate incidence and etiology of early (within 1 month from surgery and occurring in the intensive care unit [ICU]) postoperative infections as well as donor- and recipient-related risk factors.

METHODS

The data of 280 patients undergoing 299 consecutive liver transplant procedures from January 2012 to December 2015 were extracted from the Italian ICU registry database and hospital registries. Perioperative risk factors, etiology of infections, and antibiotic susceptibility of isolated microorganisms were taken into consideration.

RESULTS

Global incidence of postoperative infections was 21%. Pneumonia was the most frequent infection and, globally, gram-negative bacteria were the most common agents. Septic shock was present in 22% of infection cases and hospital mortality was higher in patients with postoperative infection. Preoperative chronic obstructive pulmonary disease, malnutrition, preoperative ascites, encephalopathy, and early re-transplantation were significantly associated to post orthotopic LT infections.

CONCLUSION

Infections represent a major cause of early postoperative morbidity and mortality. The impact of single risk factors and the results of their preoperative management should be further investigated in order to reduce the incidence and evolution of postoperative infections.

Protective effects of new Wenshen Shengjing Decoction on cyclosporine-induced impairment of testosterone synthesis and spermatogenic apoptosis

The aim of the present study was to investigate the potential protective effects of new Wenshen Shengjing Decoction (new WSSJD; including Cornu Cervi Nippon Parvum, Panax ginseng, Cynomorium songaricum, Cistanche deserticola, Radix Astragali, Epimedium brevicornum and Angelica sinensis) on cyclosporine-induced impairment of testosterone synthesis and spermatogenic apoptosis in mice. A total of 90 adult male Kunming mice were divided into the following 6 groups: Control (no intervention), dimethylsulfoxide (DMSO; received only DMSO), cyclosporine A (CsA), clomifene citrate (CC; CsA + CC, 15 mg/kg/day), WSSJD (CsA + WSSJD, crude drug 12 g/kg/day) and new WSSJD (CsA + new WSSJD, crude drug 12 g/kg/day). All mice were treated for 30 days via oral gavage. The testes were subsequently fixed and stained with hematoxylin & eosin to assess the development of seminiferous epithelia. Immunohistochemical techniques were used to detect the expression of luteinizing hormone receptor (LHR) and P450 side chain cleavage (P450scc) in testicular Leydig cells. In addition, the apoptosis of spermatogenic cells in the testes was detected using a terminal dexynucleotidyl transferase-mediated dUTP nick-end labeling assay, and flow cytometry was used to analyze the survival rate and early apoptosis of sperm in the epididymis. Compared with the CsA and CC groups, new WSSJD administration significantly increased levels of serum testosterone and the expressions of LHR and P450scc in testicular Leydig cells (P<0.05), while the apoptosis of spermatogenic cells in the seminiferous tubules and early apoptosis of mature sperm were significantly decreased (P<0.05). These results suggest that new WSSJD may ameliorate CsA-induced spermatogenic damage in male mice by enhancing testosterone synthesis and the secretion of testicular Leydig cells, and by reducing the apoptosis of spermatogenic cells.

Delayed introduction of immunosuppressive regimens in critically ill patients after liver transplantation

BACKGROUND

The manipulation of immunosuppression therapy remains challenging in patients who develop infectious diseases or multiple organ dysfunction after liver transplantation. We evaluated the outcomes of delayed introduction of immunosuppression in the patients after liver transplantation under immune monitoring with ImmuKnow assay.

METHODS

From March 2009 to February 2014, 225 consecutive liver recipients in our institute were included. The delayed administration of immunosuppressive regimens was attempted in 11 liver recipients with multiple severe comorbidities.

RESULTS

The median duration of non-immunosuppression was 12 days (range 5-58). Due to the infectious complications, the serial ImmuKnow assay showed a significantly low ATP level of 64±35 ng/mL in the early period after transplantation. With the development of comorbidities, the ImmuKnow value significantly increased. However, the acute allograft rejection developed when a continuous distinct elevation of both ATP and glutamyltranspeptidase levels was detected. The average ATP level measured just before the development of acute rejection was 271±115 ng/mL.

CONCLUSIONS

The delayed introduction of immunosuppressive regimens is safe and effective in management of critically ill patients after liver transplantation. The serial ImmuKnow assay could provide a reliable depiction of the dynamics of functional immunity throughout the clinical course of a given patient.

Infectious diseases in solid organ transplant recipients: Analysis of autopsied cases in Japan

BACKGROUND

With the improvements in immunosuppressive agents and graft survival, infections such as mycoses have become major complications after solid organ transplantation (SOT).

METHODS

Our group has continuously updated an epidemiological database of visceral mycoses (VM) among autopsy cases in Japan since 1989. Data on infectious agents and clinical information were complied using similar procedures.

RESULTS

Among the all autopsied cases studied, 356 undergone SOT. Of these, 214 (60.1%) suffered from one or more types of infections, including 51 (14.3%) with VM. Thus, the incidence of VM was higher in SOT recipients than in non-transplanted cases (P < 0.0001). Aspergillus spp. (Asp) was the most predominant agent and Candida spp. was second. Specifically, among SOT recipients, Asp was the most predominant in liver and lung transplant recipients. Among the 217 autopsied liver transplants cases, the incidence of VM was highest in those with fulminant hepatitis (FH, P = 0.01). The incidence of cytomegalovirus infection tended to be higher in cases with mycosis (P = 0.06). Multivariate logistic regression analysis identified FH (odds ratio, 3.61, 95% confidence interval 1.34-9.75; P = 0.03) as an independent risk factor for mycosis in liver transplant recipients.

CONCLUSION

This epidemiological analysis of autopsied cases provides a strong incentive to intensify efforts to diagnose and treat post-SOT infectious diseases.

Machine-Learning Algorithms Predict Graft Failure After Liver Transplantation

BACKGROUND

The ability to predict graft failure or primary nonfunction at liver transplant decision time assists utilization of scarce resource of donor livers, while ensuring that patients who are urgently requiring a liver transplant are prioritized. An index that is derived to predict graft failure using donor and recipient factors, based on local data sets, will be more beneficial in the Australian context.

METHODS

Liver transplant data from the Austin Hospital, Melbourne, Australia, from 2010 to 2013 has been included in the study. The top 15 donor, recipient, and transplant factors influencing the outcome of graft failure within 30 days were selected using a machine learning methodology. An algorithm predicting the outcome of interest was developed using those factors.

RESULTS

Donor Risk Index predicts the outcome with an area under the receiver operating characteristic curve (AUC-ROC) value of 0.680 (95% confidence interval [CI], 0.669-0.690). The combination of the factors used in Donor Risk Index with the model for end-stage liver disease score yields an AUC-ROC of 0.764 (95% CI, 0.756-0.771), whereas survival outcomes after liver transplantation score obtains an AUC-ROC of 0.638 (95% CI, 0.632-0.645). The top 15 donor and recipient characteristics within random forests results in an AUC-ROC of 0.818 (95% CI, 0.812-0.824).

CONCLUSIONS

Using donor, transplant, and recipient characteristics known at the decision time of a transplant, high accuracy in matching donors and recipients can be achieved, potentially providing assistance with clinical decision making.

Pre-Transplantation Immune Cell Distribution and Early Post-Transplant Fungal Infection Are the Main Risk Factors of Liver Transplantation Recipients in Lower Model of End-Stage Liver Disease

BACKGROUND

The prognosis of patients after liver transplantation (LTx) with high Model of End-Stage Liver Disease (MELD) score (>30) is predicted, but patients with lower MELD scores (<30) have no conclusive studies of pre- and post-transplant risk factors that influence the long-term outcome.

METHODS

This retrospective study reviewed 268 recipients with MELD score <30, from 2008 to 2013 in our institution, for evaluation of pre-transplant risk factors including patients' clinical background data, pre-transplant lymphocyte subpopulation, and early post-transplant infection complication as predictors for long-term survival after LTx.

RESULTS

The post-transplant patients' survival estimates were 90.7%, 85.1%, and 83.6% at 1, 3, and 5 years, respectively. In multivariate analysis, age >55years, presence of ascites, cluster of differentiation (CD)3 < 93.2 (count/μL), CD4/CD8 <2.4, fungal infection, and more than one site of fungal colonization significantly influenced survival (P = .0003, P = .002, P = .04, P = .004, P < .0001, and P > .0001, respectively). We also noticed that these five factors accumulatively influence the long-term survival rate; this means that in the presence of any two risk factors, the 5-year survival can still be 88.4%, whereas in the presence of any three risk factors, the survival rate dropped to only 57.1%.

CONCLUSIONS

Older patients in the presence of pre-transplant low immune cell number and ascites in association with post-transplant fungal infection are the independent risk factors in MELD scores <30 LTx groups for long-term survival. Patients in these groups with any of the three factors had inferior long-term survival results.

Evaluation of T Cell Immunity against Human Cytomegalovirus: Impact on Patient Management and Risk Assessment of Vertical Transmission

Cytomegalovirus (CMV) is one of the most common infectious agents, infecting the general population at an early age without causing morbidity most of the time. However, on particular occasions, it may represent a serious risk, as active infection is associated with rejection and disease after solid organ transplantation or fetal transmission during pregnancy. Several methods for CMV diagnosis are available on the market, but because infection is so common, careful selection is needed to discriminate primary infection from reactivation. This review focuses on methods based on CMV-specific T cell reactivity to help monitor the consequences of CMV infection/reactivation in specific categories of patients. This review makes an attempt at discussing the pros and cons of the methods available.

A translationally optimized AAV-UGT1A1 vector drives safe and long-lasting correction of Crigler-Najjar syndrome

Crigler-Najjar syndrome is a severe metabolic disease of the liver due to a reduced activity of the UDP Glucuronosyltransferase 1A1 (UGT1A1) enzyme. In an effort to translate to the clinic an adeno-associated virus vector mediated liver gene transfer approach to treat Crigler-Najjar syndrome, we developed and optimized a vector expressing the UGT1A1 transgene. For this purpose, we designed and tested in vitro and in vivo multiple codon-optimized UGT1A1 transgene cDNAs. We also optimized noncoding sequences in the transgene expression cassette. Our results indicate that transgene codon-optimization is a strategy that can improve efficacy of gene transfer but needs to be carefully tested in vitro and in vivo. Additionally, while inclusion of introns can enhance gene expression, optimization of these introns, and in particular removal of cryptic ATGs and splice sites, is an important maneuver to enhance safety and efficacy of gene transfer. Finally, using a translationally optimized adeno-associated virus vector expressing the UGT1A1 transgene, we demonstrated rescue of the phenotype of Crigler-Najjar syndrome in two animal models of the disease, Gunn rats and Ugt1a1^-/- mice. We also showed long-term (>1 year) correction of the disease in Gunn rats. These results support further translation of the approach to humans.

Microbial epidemiology and risk factors of infections in recipients after DCD liver transplantation

AIM

Infection is a major cause of increased mortality after a liver transplant (LT). This study sought to identify the incidence, prevalence and risk factors of microbial infection for recipients who underwent LT using grafts from donors after cardiac death (DCD).

METHODS

We retrospectively analysed the frequency and characteristics of post-transplantation infections in 236 recipients who underwent DCD LT between 1 January 2010 and 31 December 2014 in our centre and evaluated the risk factors of post-transplantation infection.

RESULTS

Overall, 162 recipients acquired at least one type of infection during hospitalisation after LT, and the morbidity rate was 68.6%. Moreover, 19 of the 236 recipients died, with an overall mortality rate of 8.1%. In total, 752 pathogens were isolated. Gram-positive bacteria, Gram-negative bacteria and fungi accounted for 26.1% (196), 58.2% (438) and 15.7% (118) of the pathogens, respectively. Kaplan-Meier curves of 1-year survival showed that recipients with infection had a significantly lower cumulative survival rate compared with those without infection (83.2% vs. 90.6%, p < 0.05). Multivariate analysis revealed that age > 60 years (p = 0.010) and severe hepatitis (p = 0.036) were independent risk factors for infection during hospitalisation after LT.

CONCLUSION

Infection is a common complication after a DCD-LT that could impair 1-year survival. We suggest physicians pay more attention to the infection of recipients post-LT, especially those recipients greater than 60 years of age and those who suffered from severe hepatitis.

Associating Changes in the Immune System with Clinical Diseases for Interpretation in Risk Assessment

This overview is an update of the unit originally published in 2004. While the basic tenets of immunotoxicity have not changed in the past 10 years, several publications have explored the application of immunotoxicological data to the risk assessment process. Therefore, the goal of this unit is still to highlight relationships between xenobiotic-induced immunosuppression and risk of clinical diseases progression. In immunotoxicology, this may require development of models to equate moderate changes in markers of immune functions to potential changes in incidence or severity of infectious diseases. For most xenobiotics, exposure levels and disease incidence data are rarely available, and safe exposure levels must be estimated based on observations from experimental models or human biomarker studies. Thus, it is important to establish a scientifically sound framework that allows accurate and quantitative interpretation of experimental or biomarker data in the risk assessment process.