High frequency of central memory regulatory T cells allows detection of liver recipients at risk of early acute rejection within the first month after transplantation

Monitoring of Serological, Cellular and Genomic Biomarkers in Transplantation, Computational Prediction Models and Role of Cell-Free DNA in Transplant Outcome

The process and evolution of an organ transplant procedure has evolved in terms of the prevention of immunological rejection with the improvement in the determination of immune response genes. These techniques include considering more important genes, more polymorphism detection, more refinement of the response motifs, as well as the analysis of epitopes and eplets, its capacity to fix complement, the PIRCHE algorithm and post-transplant monitoring with promising new biomarkers that surpass the classic serum markers such as creatine and other similar parameters of renal function. Among these new biomarkers, we analyze new serological, urine, cellular, genomic and transcriptomic biomarkers and computational prediction, with particular attention to the analysis of donor free circulating DNA as an optimal marker of kidney damage.

Importance of human leukocyte antigen antibodies and leukocyte antigen/killer-cell immunoglobulin-like receptor genes in liver transplantation

Many mechanisms have been proposed to explain the hypothetical state of hepatic tolerance, which is described by eventual imbalances or deregulation in the balance of cytokines, mediators, effectors, and regulatory cells in the complex milieu of the liver. In this section, we will comment on the importance of donor-specific anti-human leukocyte antigen (HLA) antibodies (DSA) as well as the compatibility and pairings of HLA and killer-cell immunoglobulin-like receptor (KIR) genotypes in the evolution of liver transplantation. Thus, HLA compatibility, viral infections, and HLA-C/KIR combinations have all been linked to liver transplant rejection and survival. There have been reports of increased risk of acute and chronic rejection with ductopenia, faster graft fibrosis, biliary problems, poorer survival, and even de novo autoimmune hepatitis when DSAs are present in the recipient. Higher mean fluorescence intensity (MFI) values of the DSAs and smaller graft size were associated with poorer patient outcomes, implying that high-risk patients with preformed DSAs should be considered for selecting the graft placed and desensitization methods, according to the investigators. Similarly, in a combined kidney-liver transplant, a pretransplant with a visible expression of several DSAs revealed that these antibodies were resistant to treatment. The renal graft was lost owing to antibody-mediated rejection (AMR). The HLA antigens expressed by the transplanted liver graft influenced antibody elimination. Pathologists are increasingly diagnosing AMR in liver transplants, and desensitization therapy has even been employed in situations of AMR, particularly in patients with DSAs in kidney-hepatic transplants and high-class II MFI due to Luminex. In conclusion, after revealing the negative impacts of DSAs with high MFI, pretransplant virtual crossmatch techniques may be appropriate to improve evolution; however, they may extend cold ischemia periods by requiring the donor to be typed.

Comparison of FOXP3 and Interleukin 35 Expression Profiles in Kidney Transplant Recipients With Excellent Long-Term Graft Function and Acute Rejection

OBJECTIVES

Transplant tolerance is defined as graft acceptance without long-term use of immunosuppressive agents. Regulatory T cells are involved in the maintenance of peripheral self-tolerance by actively suppressing the activation and expansion of autoreactive T cells. In the present study, we compared the expression profiles of forkhead box protein P3 (FOXP3) and interleukin 35 in kidney transplant recipients who had excellent long-term graft function under immunosuppression versus recipients who had acute rejection.

MATERIALS AND METHODS

The 40 kidney transplant recipients included in this study were divided into 2 groups: 27 recipients with excellent long-term graft function and 13 recipients with acute rejection. After collection of whole peripheral blood, peripheral blood mononuclear cells were isolated from the blood samples. After RNAextraction and cDNAsynthesis from each collected sample, expression levels of interleukin 35 and FOXP3 were determined using in-house SYBER green-based real-time polymerase chain reaction. We used t tests to analyze data.

RESULTS

Mean ages of recipients with excellent longterm graft function and recipients with acute rejection were 42.1 and 45.5 years, respectively. We found that FOXP3 and interleukin 35 expression levels were significantly increased in recipients with excellentlongterm graftfunction comparedwith recipientswith acute rejection. FOXP3 expression levels were significantly higher in those with excellent long-term graft function with graft survivalrate of <10 years,whereas interleukin 35 expression levels were significantly higher in patients with graft survival rate >10 years (P < .05). Expression levels of FOXP3 and interleukin 35 were greater in those from 35 to 50 years old versus with those in the other age ranges.

CONCLUSIONS

Expression patterns of FOXP3 and interleukin 35 may have the potential to be used as prognostic biomarkers for kidney transplant outcomes.

PCR Array Technology in Biopsy Samples Identifies Up-Regulated mTOR Pathway Genes as Potential Rejection Biomarkers After Kidney Transplantation

Background: Antibody-mediated rejection (AMR) is the major cause of kidney transplant rejection. The donor-specific human leukocyte antigen (HLA) antibody (DSA) response to a renal allograft is not fully understood yet. mTOR complex has been described in the accommodation or rejection of transplants and integrates responses from a wide variety of signals. The aim of this study was to analyze the expression of the mTOR pathway genes in a large cohort of kidney transplant patients to determine its possible influence on the transplant outcome. Methods: A total of 269 kidney transplant patients monitored for DSA were studied. The patients were divided into two groups, one with recipients that had transplant rejection (+DSA/+AMR) and a second group of recipients without rejection (+DSA/-AMR and -DSA/-AMR, controls). Total RNA was extracted from kidney biopsies and reverse transcribed to cDNA. Human mTOR-PCR array technology was used to determine the expression of 84 mTOR pathway genes. STRING and REVIGO software were used to simulate gene to gene interaction and to assign a molecular function. Results: The studied groups showed a different expression of the mTOR pathway related genes. Recipients that had transplant rejection showed an over-expressed transcript (≥5-fold) of AKT1S1, DDIT4, EIF4E, HRAS, IGF1, INS, IRS1, PIK3CD, PIK3CG, PRKAG3, PRKCB (>12-fold), PRKCG, RPS6KA2, TELO2, ULK1, and VEGFC, compared with patients that did not have rejection. AKT1S1 transcripts were more expressed in +DSA/-AMR biopsies compared with +DSA/+AMR. The main molecular functions of up-regulated gene products were phosphotransferase activity, insulin-like grown factor receptor and ribonucleoside phosphate binding. The group of patients with transplant rejection also showed an under-expressed transcript (≥5-fold) of VEGFA (>15-fold), RPS6, and RHOA compared with the group without rejection. The molecular function of down-regulated gene products such as protein kinase activity and carbohydrate derivative binding proteins was also analyzed. Conclusions: We have found a higher number of over-expressed mTOR pathway genes than under-expressed ones in biopsies from rejected kidney transplants (+DSA/+AMR) with respect to controls. In addition to this, the molecular function of both types of transcripts (over/under expressed) is different. Therefore, further studies are needed to determine if variations in gene expression profiles can act as predictors of graft loss, and a better understanding of the mechanisms of action of the involved proteins would be necessary.

Identification of peripheral CD154+ T cells and HLA-DRB1 as biomarkers of acute cellular rejection in adult liver transplant recipients

Decreasing graft rejection and increasing graft and patient survival are great challenges facing liver transplantation (LT). Different T cell subsets participate in the acute cellular rejection (ACR) of the allograft. Cell-mediated immunity markers of the recipient could help to understand the mechanisms underlying acute rejection. This study aimed to analyse different surface antigens on T cells in a cohort of adult liver patients undergoing LT to determine the influence on ACR using multi-parametric flow cytometry functional assay. Thirty patients were monitored at baseline and during 1 year post-transplant. Two groups were established, with (ACR) and without (NACR) acute cellular rejection. Leukocyte, total lymphocyte, percentages of CD4+ CD154+ and CD8+ CD154+ T cells, human leukocyte antigen (HLA) mismatch between recipient-donor and their relation with ACR as well as the acute rejection frequencies were analysed. T cells were stimulated with concanavalin A (Con-A) and surface antigens were analysed by fluorescence activated cell sorter (FACS) analysis. A high percentage of CD4+ CD154+ T cells (P = 0·001) and a low percentage of CD8+ CD154+ T cells (P = 0·002) at baseline were statistically significant in ACR. A receiver operating characteristic analysis determined the cut-off values capable to stratify patients at high risk of ACR with high sensitivity and specificity for CD4+ CD154+ (P = 0·001) and CD8+ CD154+ T cells (P = 0·002). In logistic regression analysis, CD4+ CD154+ , CD8+ CD154+ and HLA mismatch were confirmed as independent risk factors to ACR. Post-transplant percentages of both T cell subsets were significantly higher in ACR, despite variations compared to pretransplant. These findings support the selection of candidates for LT based on the pretransplant percentages of CD4+ CD154+ and CD8+ CD154+ T cells in parallel with other transplant factors.

Single-cell RNA sequencing identifies inflammatory tissue T cells in eosinophilic esophagitis

T cell heterogeneity is highly relevant to allergic disorders. We resolved the heterogeneity of human tissue CD3+ T cells during allergic inflammation, focusing on a tissue-specific allergic disease, eosinophilic esophagitis (EoE). We investigated 1088 single T cells derived from patients with a spectrum of disease activity. Eight disparate tissue T cell subtypes (designated T1-T8) were identified, with T7 and T8 enriched in the diseased tissue. The phenotypes of T7 and T8 resemble putative Treg (FOXP3+) and effector Th2-like (GATA3+) cells, respectively. Prodigious levels of IL-5 and IL-13 were confined to HPGDS+ CRTH2+IL-17RB+FFAR3+CD4+ T8 effector Th2 cells. EoE severity closely paralleled a lipid/fatty acid-induced activation node highlighted by the expression of the short-chain fatty acid receptor FFAR3. Ligands for FFAR3 induced Th2 cytokine production from human and murine T cells, including in an in vivo allergy model. Therefore, we elucidated the defining characteristics of tissue-residing CD3+ T cells in EoE, a specific enrichment of CD4+ Treg and effector Th2 cells, confinement of type 2 cytokine production to the CD4+ effector population, a highly likely role for FFAR3 in amplifying local Th2 responses in EoE, and a resource to further dissect tissue lymphocytes and allergic responses.

Modeling anti-CD19 CAR T cell therapy in humanized mice with human immunity and autologous leukemia

Background

Adoptive immunotherapy using T cells expressing chimeric antigen receptors (CARs) targeting CD19 has produced remarkable clinical outcomes. However, much of the mechanisms of action, such as the development of memory responses and sources of immune cytokines, remain elusive largely due to the challenge of characterizing human CAR T cell function in vivo. The lack of a suitable in vivo model also hinders the development of new CAR T cell therapies.

Methods

We established a humanized mouse (hu-mouse) model with a functional human immune system and genetically-matched (autologous) primary acute B-lymphoblastic leukemia (B-ALL) that permits modeling of CD19-targeted CAR T cell therapy in immunocompetent hosts without allogeneic or xenogeneic immune responses.

Findings

Anti-CD19 CAR T cells were detected in blood of leukemic hu-mice with kinetics and levels similar to those seen in patients receiving CAR T cell therapy. The levels of CAR T cells were correlated inversely with the burden of leukemia cells and positively with the survival times in anti-CD19 CAR T cell-treated leukemic hu-mice. Infusion of anti-CD19 CAR T cells also resulted in rapid production of T cell- and monocyte/macrophage-derived cytokines and an increase in frequency of regulatory T cells as reported in clinical studies.

Interpretation

These results provide a proof-of-principle that this novel preclinical model has the potential to be used to model human CAR T cell therapy and facilitate the design of new CARs with improved antitumor activity.

The number of FoxP3 regulatory T cells in the circulation may be a predictive biomarker for kidney transplant recipients: A multistage systematic review

BACKGROUND

The kinetics of the FoxP3 regulatory T-cell (Treg) population in kidney transplant recipients (KTR) are related to the clinical effect of immunosuppression based on mammalian Target Of Rapamycin inhibitors (mTORi) with/without belatacept (predictive biomarker).

METHODS

A multistage systematic review of published and unpublished literature is presented [registration IDs in the International Prospective Register of Systematic Reviews (PROSPERO): CRD42017057570, CRD42018085019, CRD42018084941, CRD42018085186]. A multidisciplinary supervision mechanism for contextualizing of search findings was required. The peripheral blood immune cell phenotypes encompassing all regulatory cells in KTRs were assessed in order to suggest new markers of acute rejection-associated acute allograft dysfunction (AR/AAD) events in KTRs treated with mTORi alone or combined to belatacept. Quantitative estimates and evaluation of the body of evidence are provided.

RESULTS

An increase in Tregs and other regulatory cell types in the circulation in KTRs under mTORi with/without belatacept were observed. Patients with increased Tregs presented a low frequency of AR/AAD events compared to those in which the number of Tregs remained unchanged or even diminished [Odds Ratio (OR)/95% confidence interval (95% CI)/I²/number of studies (n): 0.31/0.10-0.93/0%/6]. Nevertheless, there are too few trials to consider Tregs in the circulation as a predictive biomarker. Inadequate reporting prevents appreciating clinical relevance in such studies.

CONCLUSIONS

Despite advances, clinical qualification of potential predictive biomarkers continues to be difficult. Clinical evidence on Tregs in KTRs needs to be enlarged. Biomarkers should be able to evaluate the effect of medicines targeted to specific patient populations.

High circulating CD4+CD25hiFOXP3+ T-cell sub-population early after lung transplantation is associated with development of bronchiolitis obliterans syndrome

BACKGROUND

Chronic bronchiolitis obliterans syndrome (BOS) remains a major limitation for long-term survival after lung transplantation. The immune mechanisms involved and predictive biomarkers have yet to be identified. The purpose of this study was to determine whether peripheral blood T-lymphocyte profile could predict BOS in lung transplant recipients.

METHODS

An in-depth profiling of CD4⁺ and CD8⁺ T cells was prospectively performed on blood cells from stable (STA) and BOS patients with a longitudinal follow-up. Samples were analyzed at 1 and 6 months after transplantation, at the time of BOS diagnosis, and at an intermediate time-point at 6 to 12 months before BOS diagnosis.

RESULTS

Although no significant difference was found for T-cell compartments at BOS diagnosis or several months beforehand, we identified an increase in the CD4⁺CD25^hiFoxP3⁺ T-cell sub-population in BOS patients at 1 and 6 months after transplantation (3.39 ± 0.40% vs 1.67 ± 0.22% in STA, p < 0.001). A CD4⁺CD25^hiFoxP3⁺ T-cell threshold of 2.4% discriminated BOS and stable patients at 1 month post-transplantation. This was validated on a second set of patients at 6 months post-transplantation. Patients with a proportion of CD4⁺CD25^hiFoxP3⁺ T cells up to 2.4% in the 6 months after transplantation had a 2-fold higher risk of developing BOS.

CONCLUSIONS

This study is the first to report an increased proportion of circulating CD4⁺CD25^hiFoxP3⁺ T cells early post-transplantation in lung recipients who proceed to develop BOS within 3 years, which supports its use as a BOS predictive biomarker.

In vitro intracellular IFNγ, IL-17 and IL-10 producing T cells correlates with the occurrence of post-transplant opportunistic infection in liver and kidney recipients

AIM

To validate intracellular cytokine production functional assay as means of cell-mediated immunity monitoring of post-transplant patients with opportunistic infection (OI).

METHODS

Intracellular cytokine-producing CD4⁺ and CD8⁺ T-cell monitoring was carried out in 30 liver transplant (LTr) and 31 kidney transplant (KTr) recipients from 2010 to 2012. Patients were assessed in our Department of Immunology at the Clinical University ‘Hospital Virgen de la Arrixaca-IMIB’ in Murcia, Spain for one year following transplantation. FACS Canto II flow cytometer was employed to quantify the intracellular production of IL-17, IFNγ and IL-10 cytokines on stimulated CD4⁺CD69⁺ and CD8⁺CD69⁺ T cells and BD FACS DIVA v.6 software was used to analysed the data. Statistical analysis was carried out using SPSS 22.0.

RESULTS

LTr with OI had significantly lower % of CD8⁺CD69⁺IFNγ⁺ T cells at 60 (7.95 ± 0.77 vs 26.25 ± 2.09, P < 0.001), 90 (7.47 ± 1.05 vs 30.34 ± 3.52, P < 0.001) and 180 (15.31 ± 3.24 vs 24.59 ± 3.28, P = 0.01) d post-transplantation. Higher % of CD4⁺CD69⁺IL-10⁺ as well as CD4⁺CD69⁺IL-17⁺ T cells were yet reported at 30 (14.06 ± 1.65 vs 6.09 ± 0.53, P = 0.0007 and 4.23 ± 0.56 vs 0.81 ± 0.14, P = 0.005; respectively), 60 (11.46 ± 1.42 vs 4.54 ± 0.91, P = 0.001 and 4.21 ± 0.59 vs 1.43 ± 0.42, P = 0.03; respectively) and 90 d (16.85 ± 1.60 vs 4.07 ± 0.63, P < 0.001 and 3.97 ± 0.43 vs 0.96 ± 0.17, P = 0.001). Yet, KTr with OI had significantly lower percentage of CD4⁺CD69⁺IFNγ⁺ at 30 (11.80 ± 1.59 vs 20.64 ± 3.26, P = 0.035), 60 (11.19 ± 1.35 vs 15.85 ± 1.58, P = 0.02), 90 (11.37 ± 1.42 vs 22.99 ± 4.12, P = 0.028) and 180 (13.63 ± 2.21 vs 21.93 ± 3.88, P = 0.008) d post-transplantation as opposed to CD4⁺CD69⁺IL-10⁺ and CD8⁺CD69⁺IL-10⁺ T cells which percentages were higher at 30 (25.21 ± 2.74 vs 8.54 ± 1.64, P < 0.001 and 22.37 ± 1.35 vs 17.18 ± 3.54, P = 0.032; respectively), 90 (16.85 ± 1.60 vs 4.07 ± 0.63, P < 0.001 and 23.06 ± 2.89 vs 10.19 ± 1.98, P = 0.002) and 180 (21.81 ± 1.72 vs 6.07 ± 0.98, P < 0.001 and 19.68 ± 2.27 vs 10.59 ± 3.17, P = 0.016) d post-transplantation. The auROC curve model determined the most accurate cut-off values to stratify LTr and KTr at high risk of OI and Cox Regression model confirmed these biomarkers as the most significant risk factors to opportunistic infection.

CONCLUSION

Post-transplant percentages of T-cell subsets differed significantly amongst infected- and non-infected-LTr and -KTr and yet this imbalance was found to contribute towards a worst clinical outcome.

Interleukin-35 mitigates the function of murine transplanted islet cells via regulation of Treg/Th17 ratio

Pancreatic islet transplantation is a promising treatment for type 1 diabetes (T1D). Interleukin-35 (IL-35) is a recently discovered cytokine that exhibits potent immunosuppressive functions. However, the role of IL-35 in islet transplant rejection remains to be elucidated. In this study, we isolated islet cells of BALB/c mouse and purified CD4+ T cell subsets of a C57BL/6 mouse. The model for islet transplantation was established in vitro by co-culture of the islet cells and CD4+ T cells. IL-35 (20 ng/ml) was administered every other day. Following co-culture, the islet function and Treg/Th17 ratio were analyzed on days 1, 3, and 5. Furthermore, the Th17/Treg ratio was modulated (1:0–2), and the function of islet cells as well as proliferation of Th17 cells were analyzed. T cell sorting was performed using the magnetic bead sorting method; Treg and Th17 count using flow cytometry; cell proliferation detection using the carboxyfluorescein diacetate succinimidyl ester (CFSE) method, and islet function test using the sugar stimulation test. Results showed that Th17 counts increased in the co-culture system. However, after administration of IL-35, the number of Treg cells increased significantly compared to that in the control group (50.7% of total CD4+ T cells on day 5 in IL-35 group vs. 9.5% in control group) whereas the proliferation rate of Th17 cells was significantly inhibited (0.3% in IL-35 group vs. 7.2% in control group on day 5). Reducing the Th17/Treg ratio significantly improved the function of transplanted islets. Treg inhibited Th17 proliferation and IL-35 enhanced this inhibitory effect. IL-35 mitigates the function of murine transplanted islet cells via regulation of the Treg/Th17 ratio. This might serve as a potential therapeutic strategy for in-vivo islet transplant rejection and T1D.

CD28 biomarker quantification and expression level profiles in CD4+ T-lymphocytes in solid organ transplantation

The introduction of anti-calcineurin-based therapies has led to an increase in the one-year survival as well as graft function rates in patients undergoing solid organ transplantation (SOT). Nonetheless, early cellular acute rejection (EAR) incidence still remains a major challenge that irrevocably heads to poor outcomes. The mechanisms underlying CD4 T cell activation in SOT are still under research. In this sense, CD28 co-stimulatory molecule plays a pivotal role triggering CD4 T cell activation as well as survival maintenance. Previous own studies stated the role that CD4⁺CD28⁺ circulating T lymphocytes plays before and during EAR episodes. We assessed the percentage as well as the absolute number of CD28 molecules on CD4⁺ T cells as predictive surrogate biomarker of EAR in a prospective cohort of liver and kidney transplant recipients. Quantitative analysis of CD28 was carried out on whole peripheral blood samples by flow cytometry. Decreased pre-transplant expression of CD28 was associated with EAR in both study groups. Furthermore, the expression of CD28 within the rejected group, experimented an up-regulation upon transplantation. These preliminary results suggest that patients undergoing liver or kidney transplant can be stratified at high risk of EAR according to their CD28 molecule expression on peripheral CD4⁺ T lymphocytes.

Combined Detection of Serum IL-10, IL-17, and CXCL10 Predicts Acute Rejection Following Adult Liver Transplantation

Discovery of non-invasive diagnostic and predictive biomarkers for acute rejection in liver transplant patients would help to ensure the preservation of liver function in the graft, eventually contributing to improved graft and patient survival. We evaluated selected cytokines and chemokines in the sera from liver transplant patients as potential biomarkers for acute rejection, and found that the combined detection of IL-10, IL-17, and CXCL10 at 1-2 weeks post-operation could predict acute rejection following adult liver transplantation with 97% specificity and 94% sensitivity.