Longitudinal assessment of T cell inhibitory receptors in liver transplant recipients and their association with posttransplant infections

Exhaustion of T cells after renal transplantation

Renal transplantation is a life-saving treatment for patients with end-stage renal disease. However, the challenge of transplant rejection and the complications associated with immunosuppressants necessitates a deeper understanding of the underlying immune mechanisms. T cell exhaustion, a state characterized by impaired effector functions and sustained expression of inhibitory receptors, plays a dual role in renal transplantation. While moderate T cell exhaustion can aid in graft acceptance by regulating alloreactive T cell responses, excessive exhaustion may impair the recipient's ability to control viral infections and tumors, posing significant health risks. Moreover, drugs targeting T cell exhaustion to promote graft tolerance and using immune checkpoint inhibitors for cancer treatment in transplant recipients are areas deserving of further attention and research. This review aims to provide a comprehensive understanding of the changes in T cell exhaustion levels after renal transplantation and their implications for graft survival and patient outcomes. We discuss the molecular mechanisms underlying T cell exhaustion, the role of specific exhaustion markers, the potential impact of immunosuppressive therapies, and the pharmaceutical intervention on T cell exhaustion levels. Additionally, we demonstrate the potential to modulate T cell exhaustion favorably, enhancing graft survival. Future research should focus on the distinctions of T cell exhaustion across different immune states and subsets, as well as the interactions between exhausted T cells and other immune cells. Understanding these dynamics is crucial for optimizing transplant outcomes and ensuring long-term graft survival while maintaining immune competence.

Pre-transplant Biomarkers of Immune Dysfunction Improve Risk Assessment of Post-transplant Mortality Compared to Conventional Clinical Risk Scores

Introduction

There is a critical need to accurately stratify liver transplant (LT) candidates' risk of post-LT mortality prior to LT to optimize patient selection and avoid futility. Here, we compare previously described pre-LT clinical risk scores with the recently developed Liver Immune Frailty Index (LIFI) for prediction of post-LT mortality. LIFI measures immune dysregulation based on pre-LT plasma HCV IgG, MMP3 and Fractalkine. LIFI accurately predicts post-LT mortality, with LIFI-low corresponding to 1.4% 1-year post-LT mortality compared with 58.3% for LIFI-high (C-statistic=0.85).

Methods

LIFI was compared to MELD, MELD-Na, MELD 3.0, D-MELD, MELD-GRAIL, MELD-GRAIL-Na, UCLA-FRS, BAR, SOFT, P-SOFT, and LDRI scores on 289 LT recipients based on waitlist data at the time of LT. Survival, hazard of early post-LT death, and discrimination power (C-statistic) were assessed.

Results

LIFI showed superior discrimination (highest C-statistic) for post-LT mortality when compared to all other risk scores, irrespective of biologic MELD. On univariate analysis, the LIFI showed a significant correlation with mortality 6-months, as well as 1-, 3-, and 5-years. No other pre-LT scoring system significantly correlated with post-LT mortality. On bivariate adjusted analysis, African American race (p<0.05) and pre-LT cardiovascular disease (p=0.053) were associated with early- and long-term post-LT mortality. Patients who died within 1-yr following LT had a significantly higher incidence of infections, including 30-day and 90-day incidence of any infection, pneumonia, abdominal infections, and UTI (p<0.05).

Conclusions

LIFI, which measures pre-LT biomarkers of immune dysfunction, more accurately predicts risk of post-LT futility compared with current clinical predictive models. Pre-LT assessment of immune dysregulation may be critical in predicting mortality after LT and may optimize selection of candidates with lowest risk of futile outcomes.

Innate immune cell dysfunction and systemic inflammation in children with chronic liver diseases undergoing transplantation

Advanced liver diseases (ALD) can affect immune function and compromise host defense against infections. In this study, we examined the phenotypic and functional alterations in circulating monocyte and dendritic cells (DCs) in children with ALD undergoing liver transplantation (LT). Children were stratified into 2 clusters, C1 (mild) and C2 (severe), on the basis of laboratory parameters of ALD and compared with healthy pediatric controls. Children in C2 had a significant reduction in frequencies of nonclassical monocytes and myeloid DCs. Children in C2 displayed monocyte and DC dysfunction, characterized by lower human leucocyte antigen DR expression and reduced interleukin 12 production, and had an increased incidence of infections before and after LT. Children in C2 demonstrated immune dysregulation with elevations of pro- and anti-inflammatory cytokines in plasma. Alterations of innate immune cells correlated with multiple laboratory parameters of ALD, including plasma bile acids. In vitro, monocytes cultured with specific bile acids demonstrated a dose-dependent reduction in interleukin 12 production, similar to alterations in children with ALD. In conclusion, a cohort of children with ALD undergoing LT exhibited innate immune dysfunction, which may be related to the chronic elevation of serum bile acids. Identifying at-risk patients may permit personalized management pre- and post-transplant, thereby reducing the incidence of infection-related complications.

Assessment of neutrophil subsets and immune checkpoint inhibitor expressions on T lymphocytes in liver transplantation: A preliminary study beyond the neutrophil-lymphocyte ratio

Background: Advanced stages of cirrhosis are characterized by the occurrence of progressive immune alterations known as CAID (Cirrhosis Associated Immune Dysfunction). In advanced cirrhosis, liver transplantation (LT) remains the only curative treatment. Sepsis, shares many similarities with decompensated cirrhosis in terms of immuno-inflammatory response. In both conditions, the neutrophil-lymphocyte ratio (NLR) is associated with poor outcomes. Based on alterations in sepsis, we hypothesized that we could observe in cirrhotic and LT patients more detailed neutrophil and lymphocyte phenotypes. To this end, along with leukocyte count, we assessed immature neutrophils, LOX-1⁺ MDSC and PD-1 and TIM-3 lymphocyte expressions in cirrhotic patients before transplantation in association with liver disease severity and during the first month after transplantation. Methods: We conducted a prospective monocentric study including cirrhotic patients registered on LT waiting-list. Blood samples were collected at enrolment before LT and for 1 month post-LT. In addition to NLR, we assessed by whole blood flow cytometry the absolute count of immature neutrophils and LOX-1⁺ MDSC as well as the expressions of immune checkpoint receptors PD-1 and TIM-3 on T lymphocytes. Results: We included 15 healthy volunteers (HV) and 28 patients. LT was performed for 13 patients. Pre-LT patients presented with a higher NLR compared to HV and NLR was associated with cirrhosis severity. Increased immature neutrophils and LOX-1⁺ MDSC counts were observed in the most severe patients. These alterations were mainly associated with acute decompensation of cirrhosis. PD-1 and TIM-3 expressions on T lymphocytes were not different between patients and HV. Post-LT immune alterations were dominated by a transitory but tremendous increase of NLR and immature neutrophils during the first days post-LT. Then, immune checkpoint receptors and LOX-1⁺ MDSC tended to be overexpressed by the second week after surgery. Conclusion: The present study showed that NLR, immature neutrophils and LOX-1⁺ MDSC counts along with T lymphocyte count and checkpoint inhibitor expression were altered in cirrhotic patients before and after LT. These data illustrate the potential interest of immune monitoring of cirrhotic patients in the context of LT in order to better define risk of sepsis. For this purpose, larger cohorts of patients are now necessary in order to move forward a more personalised care of LT patients.

Expansion of Double-Negative T Cells in Patients before Liver Transplantation Correlates with Post-Transplant Infections

Liver transplantation (LTx) is currently the only effective therapy for patients with end-stage liver diseases, but post-transplant infection is a key issue for morbidity and mortality. In this study, we found that pre-transplant patients with an expansion of double-negative T (DNT) cells (CD3⁺CD4⁻CD8⁻ T cells) had an increased incidence of infections within the first 6 months after LTx. These DNT cells also negatively correlated with their CD4/CD8 ratio. Compared to patients who had no infections after LTx, these DNT cells expressed more CD25, especially in the memory compartment. The receiver operating characteristic (ROC) analysis showed that the threshold area under the ROC curve of DNT cells which could be used to distinguish LTx patients with post-transplant infections from patients without infections after LTx was 0.8353 (95% CI: 0.6591–1.000). The cut-off for the pre-LTx DNT cell level was 11.35%. Although patients with post-transplant infections had decreased levels of CD4/CD8 T cells, CD8⁺ T cells in these patients were more exhausted, with higher PD-1 expression and lower IFNγ secretion. The increased levels of DNT cells in patients with post-transplant infections were still observed 2 weeks after LTx, with higher proportions of memory DNT cells. In conclusion, increased levels of DNT cells in pre-LTx patients may be valuable for the prognosis of post-transplant infections, especially within the first 6 months after LTx.

Clinical and biomarker assessment of frailty in liver transplantation

PURPOSE OF REVIEW

Liver cirrhosis results in progressive decline, or frailty, which leads to poor outcomes and decreased survival. Multiple biomarkers and clinical assessment tools for quantifying frailty in liver transplant candidates exist, but a universal scoring protocol is lacking. Criteria vary between studies and correlation with patient outcome is not always clear. This review aims to summarize the pertinent biomarkers and assessment tools of frailty in cirrhosis.

RECENT FINDINGS

As cirrhosis progresses, the resultant 'frailty' is an inseparable independent predictor of pre and posttransplant mortality. Pro-inflammatory, neuroendocrine, and adipokine factors are dysregulated - leading to paradoxical anorexia and downregulation of orexigenic signals. The resulting catabolic utilization of amino and fatty acids leads to progressive malnutrition and sarcopenia. Both functional and imaging criteria define sarcopenia in cirrhotic patients, and degree of debilitation correlates with mortality. Liver-disease-specific frailty biomarkers and scoring tools are optimal to assess physical dysfunction in cirrhotics to promote early diagnosis and intervention.

SUMMARY

Liver cirrhosis and resulting frailty are progressive and portend a poor patient prognosis. A comprehensive, validated algorithm for detecting and quantifying frailty specific to liver disease would allow for standardization and facile application in the clinical setting. Early diagnosis is key for timely intervention and improved patient outcomes.

Tacrolimus and Sirolimus Once Daily Monotherapy Regimen as a Safe and Effective Long-Term Maintenance Immunosuppressive Therapy in Pediatric Liver Transplantation

BACKGROUND

Long-term efficiency of attenuated immunosuppressive therapies is not well characterized in pediatric liver transplantation (LT).

OBJECTIVE

To assess the efficiency of tacrolimus once daily (TAC-OD) and sirolimus once daily (SLR-OD) immunosuppression in pediatric LT.

METHODS

We retrospectively evaluated 59 children who underwent LT in our center during 2002 to 2016. Those including children who underwent planned decrease in immunosuppressant dose (stable clinical conditions after 2 years of LT), and those who underwent unplanned decrease in immunosuppressant dose (because of complications such as post-transplant lymphoproliferative disorder [PTLD] and renal failure).

RESULTS

25 of 59 children underwent planned decrease in immunosuppressant dosage (mean±SD duration of 4.5±1.8, range: 3-11 years); 34 had unplanned decrease (mean±SD of 1.3±0.6, range: 0.5-2.6 years). 19 of 25 children with planned conversion received TAC-OD; 6 received SLR-OD (22 with 1 mg/day dose, and 3 with 1 mg every two days). Of 34 children with unplanned conversion, 27 received TAC-OD, 7 SLR-OD (25 children with 1 mg/day, 7 with 1 mg every two days, 1 with 0.5 mg/day TAC, and 1 with 0.5 mg TAC every two days). We found no adverse events including acute or chronic graft rejection, renal insufficiency, infections, PTLDs, or cardiovascular thrombotic events after initiation of the modified immunosuppression in none of the groups.

CONCLUSION

TAC-OD or SLR-OD monotherapies are safe and effective for long-term management of LT children with either stable clinical conditions or those with LT complications.

Influence of T Cell Coinhibitory Molecules on CD8+ Recall Responses

T cell co-signaling molecules play an important role in fine-tuning the strength of T cell activation during many types of immune responses, including infection, cancer, transplant rejection, and autoimmunity. Over the last few decades, intense research into these cosignaling molecules has provided rich evidence to suggest that cosignaling molecules may be harnessed for the treatment of immune-related diseases. In particular, coinhibitory molecules such as programmed-death 1, 2B4, BTLA, TIGIT, LAG-3, TIM-3, and CTLA-4 inhibit T cell responses by counteracting TCR and costimulatory signals, leading to the inhibition of proliferation and effector function and the downregulation of activation and adhesion molecules at the cell surface. While many reviews have focused on the role of coinhibitory molecules in modifying primary CD8⁺ T cell responses, in this review, we will consider the complex role of coinhibitory molecules in altering CD8⁺ T cell recall potential. As memory CD8⁺ T cell responses are critical for protective memory responses in infection and cancer and contribute to potentially pathogenic memory responses in transplant rejection and autoimmunity, understanding the role of coinhibitory receptor control of memory T cells may illuminate important aspects of therapeutically targeting these pathways.

Risk factors for extrapulmonary dissemination of tuberculosis and associated mortality during treatment for extrapulmonary tuberculosis

Many environmental, host, and microbial characteristics have been recognized as risk factors for dissemination of extrapulmonary tuberculosis (EPTB). However, there are few population-based studies investigating the association between the primary sites of tuberculosis (TB) infection and mortality during TB treatment. De-identified population-based surveillance data of confirmed TB patients reported from 2009 to 2015 in Texas, USA, were analyzed. Regression analyses were used to determine the risk factors for EPTB, as well as its subsite distribution and mortality. We analyzed 7007 patients with exclusively pulmonary TB, 1259 patients with exclusively EPTB, and 894 EPTB patients with reported concomitant pulmonary involvement. Age ≥45 years, female gender, human immunodeficiency virus (HIV)-positive status, and end-stage renal disease (ESRD) were associated with EPTB. ESRD was associated with the most clinical presentations of EPTB other than meningeal and genitourinary TB. Patients age ≥45 years had a disproportionately high rate of bone TB, while foreign-born patients had increased pleural TB and HIV+ patients had increased meningeal TB. Age ≥45 years, HIV+ status, excessive alcohol use within the past 12 months, ESRD, and abnormal chest radiographs were independent risk factors for EPTB mortality during TB treatment. The epidemiologic risk factors identified by multivariate analyses provide new information that may be useful to health professionals in managing patients with EPTB.