Intravenous immunoglobulins in liver transplant patients: Perspectives of clinical immune modulation

Advancing immunosuppression in liver transplantation: A narrative review

Immunosuppression is essential to ensure recipient and graft survivals after liver transplantation (LT). However, our understanding and management of the immune system remain suboptimal. Current immunosuppressive therapy cannot selectively inhibit the graft-specific immune response and entails a significant risk of serious side effects, i.e., among others, de novo cancers, infections, cardiovascular events, renal failure, metabolic syndrome, and late graft fibrosis, with progressive loss of graft function. Pharmacological research, aimed to develop alternative immunosuppressive agents in LT, is behind other solid-organ transplantation subspecialties, and, therefore, the development of new compounds and strategies should get priority in LT. The research trajectories cover mechanisms to induce T-cell exhaustion, to inhibit co-stimulation, to mitigate non-antigen-specific inflammatory response, and, lastly, to minimize the development and action of donor-specific antibodies. Moreover, while cellular modulation techniques are complex, active research is underway to foster the action of T-regulatory cells, to induce tolerogenic dendritic cells, and to promote the function of B-regulatory cells. We herein discuss current lines of research in clinical immunosuppression, particularly focusing on possible applications in the LT setting.

Immunology demystified: A guide for transplant hepatologists

Liver transplantation has become standard practice for treating end-stage liver disease. The success of the procedure relies on effective immunosuppressive medications to control the host's immune response. Despite the liver's inherent capacity to foster tolerance, the early post-transplant period is marked by significant immune reactivity. To ensure favorable outcomes, it is imperative to identify and manage various rejection types, encompassing T-cell-mediated, antibody-mediated, and chronic rejection. However, the approach to prescribing immunosuppressants relies heavily on clinical judgment rather than evidence-based criteria. Given that the majority of patients will require lifelong immuno suppression as the mechanisms underlying operational tolerance are still being investigated, healthcare providers must possess an understanding of immune responses, rejection mechanisms, and the pathways targeted by immunosuppressive drugs. This knowledge enables customization of treatments and improved patient care, even though a consensus on an optimal immunosuppressive regimen remains elusive.

Systems biology and artificial intelligence analysis highlights the pleiotropic effect of IVIg therapy in autoimmune diseases with a predominant role on B cells and complement system

Intravenous immunoglobulin (IVIg) is used as treatment for several autoimmune and inflammatory conditions, but its specific mechanisms are not fully understood. Herein, we aimed to evaluate, using systems biology and artificial intelligence techniques, the differences in the pathophysiological pathways of autoimmune and inflammatory conditions that show diverse responses to IVIg treatment. We also intended to determine the targets of IVIg involved in the best treatment response of the evaluated diseases. Our selection and classification of diseases was based on a previously published systematic review, and we performed the disease characterization through manual curation of the literature. Furthermore, we undertook the mechanistic evaluation with artificial neural networks and pathway enrichment analyses. A set of 26 diseases was selected, classified, and compared. Our results indicated that diseases clearly benefiting from IVIg treatment were mainly characterized by deregulated processes in B cells and the complement system. Indeed, our results show that proteins related to B-cell and complement system pathways, which are targeted by IVIg, are involved in the clinical response. In addition, targets related to other immune processes may also play an important role in the IVIg response, supporting its wide range of actions through several mechanisms. Although B-cell responses and complement system have a key role in diseases benefiting from IVIg, protein targets involved in such processes are not necessarily the same in those diseases. Therefore, IVIg appeared to have a pleiotropic effect that may involve the collaborative participation of several proteins. This broad spectrum of targets and 'non-specificity' of IVIg could be key to its efficacy in very different diseases.

Role of HLA-I Structural Variants and the Polyreactive Antibodies They Generate in Immune Homeostasis

Cell-surface HLA-I molecules consisting of β2-microglobulin (β2m) associated heavy chains (HCs), referred to as Face-1, primarily present peptides to CD8+ T-cells. HCs consist of three α-domains, with selected amino acid sequences shared by all alleles of all six isoforms. The cell-surface HLA undergoes changes upon activation by pathological conditions with the expression of β2m-free HCs (Face-2) resulting in exposure of β2m-masked sequences shared by almost all alleles and the generation of HLA-polyreactive antibodies (Abs) against them. Face-2 may homodimerize or heterodimerize with the same (Face-3) or different alleles (Face-4) preventing exposure of shared epitopes. Non-allo immunized males naturally carry HLA-polyreactive Abs. The therapeutic intravenous immunoglobulin (IVIg) purified from plasma of thousands of donors contains HLA-polyreactive Abs, admixed with non-HLA Abs. Purified HLA-polyreactive monoclonal Abs (TFL-006/007) generated in mice after immunizing with Face-2 are documented to be immunoregulatory by suppressing or activating different human lymphocytes, much better than IVIg. Our objectives are (a) to elucidate the complexity of the HLA-I structural variants, and their Abs that bind to both shared and uncommon epitopes on different variants, and (b) to examine the roles of those Abs against HLA-variants in maintaining immune homeostasis. These may enable the development of personalized therapeutic strategies for various pathological conditions.

Recent Improvement in Survival Outcomes and Reappraisal of Prognostic Factors in Pediatric Living Donor Liver Transplantation

Living donor liver transplantation (LDLT) is a significant advancement for the treatment of children with end-stage liver disease given the shortage of deceased donors. The ultimate goal of pediatric LDLT is to achieve complete donor safety and zero recipient mortality. We conducted a retrospective, single-center assessment of the outcomes as well as the clinical factors that may influence graft and patient survival after primary LDLTs performed between 1994 and 2020. A Cox proportional hazards model was used for multivariate analyses. The trends for independent prognostic factors were analyzed according to the following treatment eras: 1, 1994 to 2002; 2, 2003 to 2011; and 3, 2012 to 2020. Primary LDLTs were performed on 287 children during the study period. Biliary atresia (BA; 52%), acute liver failure (ALF; 26%), and monogenic liver disease (11%) were the leading indications. There were 45 graft losses (16%) and 27 patient deaths (7%) in this population during the study period. During era 1 (n = 81), the cumulative survival rates at 1 and 5 years after LDLT were 90.1% and 81.5% for patients and 86.4% and 77.8% for grafts, respectively. During era 2 (n = 113), the corresponding rates were 92.9% and 92% for patients and 89.4% and 86.7% for grafts, respectively. During era 3 (n = 93), the corresponding rates were 100% and 98.6% for patients and 98.9% and 95.4% for grafts, respectively. In the multivariate analyses, primary diagnosis ALF, bloodstream infection, posttransplant lymphoproliferative disease, and chronic rejection were found to be negative prognostic indicators for patient survival. Based on generalized care guidelines and center-oriented experiences, comprehensive advances in appropriate donor selection, refinement of surgical techniques, and meticulous medical management may eventually realize a zero-mortality rate in pediatric LDLT.

State of the art treatment of hepatitis B virus hepatocellular carcinoma and the role of hepatitis B surface antigen post-liver transplantation and resection

Chronic hepatitis B virus (HBV) infection is the major aetiology of hepatocellular carcinoma (HCC). The optimal goal of therapy, hepatitis B surface antigen (HBsAg) loss and anti-HBs production, is achieved rarely and HBsAg-associated HCC risk is well recognized. Here we review the role of HBsAg in HCC, the link between HBsAg and HCC recurrence post-liver transplantation or resection, and the implications for therapy. HBV-associated carcinogenesis is a multifactorial process. The observation that HBV-related HCC can occur in the absence of cirrhosis is compatible with a direct oncogenic effect of the virus, which may occur via multiple mechanisms, including those mediated by both mutated and unmutated HBsAg. HCC recurrence in HBsAg-positive patients post-liver transplantation has been reported in 10%-15% of patients and is likely to be because of expansion of residual HCC tumour cell populations containing integrated HBV DNA, which expand and independently replicate HBV, leading to the recurrence of both HCC and HBV. The direct role of HBsAg in HCC recurrence post-liver resection is less clear. Cirrhosis is the most important risk factor for HCC development, and precancerous cirrhotic liver remains after resection, with the potential to undergo malignant transformation regardless of the existence of HBV-derived oncogenic drivers. The role of HBsAg in the development of HCC and its recurrence post-surgical intervention has multiple implications for therapy and suggests a potential role for immunotherapy in the future management of HCC, in particular post-liver transplantation. Use of hepatitis B immunoglobulins that target HBsAg directly, alongside immune-oncology therapies, may be relevant in this setting.

Management of ganciclovir resistance cytomegalovirus infection with CMV hyperimmune globulin and leflunomide in seven cardiothoracic transplant recipients and literature review

Cytomegalovirus (CMV) disease caused by genetically resistant CMV poses a major challenge in solid organ transplant recipients, and the development of resistance is associated with increased morbidity and mortality. Antiviral resistance affects 5%-12% of patients following ganciclovir (GCV) therapy, but is more common in individuals with specific underlying risk factors. These include the CMV D+R- serostatus, type of transplanted organ, dose and duration of (Val)GCV ([V]GCV) prophylaxis, peak viral loads, and the intensity of immunosuppressive therapy. Guideline recommendations for the management of GCV resistance (GanR) in solid organ transplant recipients are based on expert opinion as there is a lack of data from controlled trials. Second-line options to treat GanR include foscarnet (FOS) and cidofovir (CDV), but these drugs are often poorly tolerated due to high rates of toxicity, such as renal dysfunction and neutropenia. Here, we report seven cardiothoracic transplant recipients with GCV resistance CMV infection from our centre treated with CMV immunoglobulin (CMVIG) +/- leflunomide (LEF) and reviewed the literature on the use of these agents in this therapeutic setting.

Prophylaxis of Hepatitis B Virus (HBV) Re-Infection in Liver Transplantation: Is the Reappearance of Hepatitis B Surface Antigen (HBsAg) Significant?

The recurrence of hepatitis B virus (HBV) infection after orthotopic liver transplantation (OLT) was in the past a primary cause of organ loss or mortality. Currently, post-OLT prophylaxis with anti-HBs immunoglobulins plus a nucleos(t)ide analogue has virtually abolished the risk of re-infection. Some studies have proposed to simplify prophylaxis by discontinuing immunoglobulins while continuing the analogue alone.

This review analysed the available studies, focusing on the recurrence of HBsAg in serum and its biological effects. In all, 16 studies were retrieved, mainly observational or retrospective, each enrolling 14 to 80 patients. Our review of the literature found that HBsAg re-appeared in 0% to 24% of the patients, generally with HBV DNA undetectable in plasma. One study measured HBsAg using a new ultra-sensitive method, which could allow a reappraisal of the incidence of recurrence. This review discusses the role of HBV surface proteins in inducing hepatocellular carcinoma, particularly when mutations in the C-terminal occur that induce stop-codons that cause defects of secretion and retention of truncated protein S, resulting in direct cell toxicity and cancer. The data on the suspension of immunoglobulins in the prophylaxis regimes of post-transplant re infection do not appear sufficiently robust for an extensive and safe application in clinical practice.

Prophylactic Anti-Cytomegalovirus Hyperimmunoglobulin in Critically Ill Liver Transplant Patients: Impact on Early Immunology and Survival

Background: Anti-cytomegalovirus hyperimmunoglobulin (CMVIg) was shown to provide beneficial immunodulatory properties beyond antiviral efficacies. The aim of this retrospective study was to assess the impact of prophylactic CMVIg treatment on early outcome following liver transplantation (LT) in critically ill patients. Methods: Forty-three cirrhotic patients requiring pre-LT intensive care due to multiorgan failure were analyzed. Twenty-eight patients with enhanced CMV risk (D+/R+; D+/R−; D−/R+) received prophylactic CMVIg for a minimum of 7 days, while 15 patients (D−/R−) did not. Results: Post-transplantation rates of intra-abdominal infections (28% vs. 61.1%; p = 0.03), Epstein–Barr virus infections (0% vs. 33.3%; p = 0.034), allograft rejections (0% vs. 22.2%; p = 0.013) and sepsis-related mortality (4% vs. 27.8%; p = 0.026) were significantly lower, whereas incidence of CMV infections (4% vs. 22.2%; p = 0.066) tended to be lower in the CMVIg subset. In multivariate analysis, only pretransplant elevated serum lactate level (hazard ratio = 34.63; p = 0.009) and absence of CMVIg therapy (hazard ratio = 21.76; p = 0.023) were identified as independent promoters of 3-month mortality. Conclusion: Prophylactic treatment with CMVIg reduces predisposition for severe immunological and septic events and, thereby, early mortality in critically ill liver recipients.

Unexpected Improvement of Liver Function by Intravenous Immunoglobulin in a Steroid-Experienced Severe Alcoholic Hepatitis

Corticosteroid is the treatment of choice for severe alcoholic hepatitis; however, it can also lead to severe life-threatening infection. We report a 28-year-old severe alcoholic hepatitis patient who did not achieve a satisfactory improvement of the liver function by corticosteroid use but obtained a significant improvement of the liver function by intravenous immunoglobulin. Intravenous immunoglobulin was administered to control infection after prolonged corticosteroid usage; however, it led to an unexpected remarkable decrease in the serum total bilirubin level and restored the responsiveness to the additional corticosteroid used after the resolution of the infection.

Immunological profiles of HIV-positive recipients of liver transplant

BACKGROUND

Scarce data are available about immune cell frequencies in HIV-positive recipients of liver transplant. Alterations in immune subsets can lead to persistent immune activation and disease progression or reduced HIV-specific responses. In liver transplantation, impaired immune tolerance can lead to organ rejection.

METHODS

HIV-positive subjects with undetectable HIVRNA and CD4 > 100/mm3 were included. Control groups were non-transplanted HIV-positive patients with similar immunovirological parameters and healthy subjects. B cells (memory, transitional, and mature subsets), T cells (effector TH1, nonclassic TH1, TH17, TH1/17; T regulatory naïve and effector subsets and CD8+ T regulatory cells), and NK cells (CD56dim and CD56bright subsets) were analyzed by flow cytometry.

RESULTS

A total of 56 patients, including 14 HIV-positive transplant recipients (HIV-LT), 14 HIV-positive controls, and 28 healthy controls were included. Median age of HIV-LT patients was 54.9 years with median time from transplant of 7.6 years. Eleven (79%) were HIV/HCV coinfected. Compared to nontransplanted patients, HIV-LT displayed significantly increased frequency of T CD8+ cells, lower percentage of T CD4+ cell, and lower number of nonclassic TH1, TH1/17 cells and naïve T CD4+ regulatory cells (Tregs). Healthy controls showed increased numbers of B cell subsets and decreased percentage of T effector subpopulations compared to HIV-LT. Compared to HIV-positive patients, healthy controls had higher B cells, NK cells, CD4+ T cells, naïve CD4+ Tregs but lower CD8+ T cells, effector Tregs, CD8+ Tregs, and all T effector cell subsets.

CONCLUSIONS

Immune cell subpopulations potentially associated with HIV progression and organ rejection were detected in HIV-positive transplant recipients. We confirmed altered frequencies of B, T, and NK cell populations in HIV-positive liver transplant recipients compared to healthy controls. The imbalance among immune cell subsets deserves further studies to identify markers of transplant outcome and potential therapeutic targets.

Cytotect®CP as salvage therapy in patients with CMV infection following allogeneic hematopoietic cell transplantation: a multicenter retrospective study

Cytomegalovirus is one of the main contributing factors to high mortality rates in patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT). The main factors of treatment failure are both drug resistance and intolerance. In some cases, Cytotect®CP CMV-hyperimmune globulin is used as salvage therapy. This study aims to investigate the safety and efficacy of Cytotect®CP as a salvage therapy in patients with CMV infection after allo-HCT. Twenty-three consecutive patients received Cytotect®CP for CMV infection after prior CMV therapy. At the time of Cytotect®CP introduction, 17 patients (74%) had developed acute GVHD and 15 patients (64%) were receiving steroid treatment; Cytotect®CP was used as monotherapy (n = 7) and in combination (n = 16). Overall, response was observed in 18 patients (78%) with a median time of 15 days (range: 3-51). Of the 18 responders, 4 experienced CMV reactivation, while 5 responders died within 100 days of beginning treatment. Of these 5 deaths, 4 were due to causes unrelated to CMV. Estimated 100-day OS from the introduction of Cytotect®CP was 69.6%. No statistically significant difference was observed in 100-day OS between responders and non-responders (73.7% vs 50.0%, p = 0.258). Cytotect®CP as salvage therapy is effective and well-tolerated. Given its safety profile, early treatment use should be considered.