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

Innate and Adaptive Immune Responses in Intestinal Transplant Rejection: Through the Lens of Inflammatory Bowel and Intestinal Graft-Versus-Host Diseases

Intestinal transplantation is a life-saving procedure utilized for patients failing total parenteral nutrition. However, intestinal transplantattion remains plagued with low survival rates and high risk of allograft rejection. The authors explore roles of innate (macrophages, natural killer cells, innate lymphoid cells) and adaptive immune cells (Th1, Th2, Th17, Tregs) in inflammatory responses, particularly inflammatory bowel disease and graft versus host disease, and correlate these findings to intestinal allograft rejection, highlighting which effectors exacerbate or suppress intestinal rejection. Better understanding of this immunology can open further investigation into potential biomolecular targets to develop improved therapeutic treatment options and immunomonitoring techniques to combat allograft rejection and enhance patient lives.

Suppressor T helper type 17 cell responses in intestinal transplant recipients with allograft rejection

BACKGROUND

Intestinal transplant (ITx) rejection is associated with memory T helper type 17 cell (Th17) infiltration of grafted tissues. Modulation of Th17 effector cell response is facilitated by T regulatory (Treg) cells, but a phenotypic characterization of this process is lacking in the context of allograft rejection.

METHODS

Flow cytometry was performed to examine the expression of surface receptors, cytokines, and transcription factors in Th17 and Treg cells in ITx control (n = 34) and rejection patients (n = 23). To elucidate key pathways guiding the rejection biology, we utilized RNA sequencing (RNAseq) and assessed epigenetic stability through pyrosequencing of the Treg-specific demethylated region (TSDR).

RESULTS

We found that intestinal allograft rejection is characterized by Treg cellular infiltrates, which are polarized toward Th17-type chemokine receptor, ROR-γt transcription factor expression, and cytokine production. These Treg cell subsets have maintained epigenetic stability, as defined by FoxP3-TSDR methylation status, but displayed upregulation of functional Treg and purinergic signaling genes by RNAseq analysis such as CD39, in keeping with suppressor Th17 properties.

CONCLUSION

We show that ITx rejection is associated with increased polarized cells that express a Th17-like phenotype concurrent with regulatory purinergic markers.

Progress in Translational Regulatory T Cell Therapies for Type 1 Diabetes and Islet Transplantation

Regulatory T cells (Tregs) have become highly relevant in the pathophysiology and treatment of autoimmune diseases, such as type 1 diabetes (T1D). As these cells are known to be defective in T1D, recent efforts have explored ex vivo and in vivo Treg expansion and enhancement as a means for restoring self-tolerance in this disease. Given their capacity to also modulate alloimmune responses, studies using Treg-based therapies have recently been undertaken in transplantation. Islet transplantation provides a unique opportunity to study the critical immunological crossroads between auto- and alloimmunity. This procedure has advanced greatly in recent years, and reports of complete abrogation of severe hypoglycemia and long-term insulin independence have become increasingly reported. It is clear that cellular transplantation has the potential to be a true cure in T1D, provided the remaining barriers of cell supply and abrogated need for immune suppression can be overcome. However, the role that Tregs play in islet transplantation remains to be defined. Herein, we synthesize the progress and current state of Treg-based therapies in T1D and islet transplantation. We provide an extensive, but concise, background to understand the physiology and function of these cells and discuss the clinical evidence supporting potency and potential Treg-based therapies in the context of T1D and islet transplantation. Finally, we discuss some areas of opportunity and potential research avenues to guide effective future clinical application. This review provides a basic framework of knowledge for clinicians and researchers involved in the care of patients with T1D and islet transplantation.

Analyses of Programmed Cell Death Protein 1 in High Immunologic-Risk Transplant Patients

Kidney transplant (KT) is the first therapeutic option for most patients with chronic renal failure that requires renal function replacement. The main complication associated with renal graft loss is immune rejection. The T regulatory pathways play a key role in this process, and abnormalities in some of these molecules could participate in the graft rejection. In this paper, our group performed an exploratory analysis of the behavior of the coinducible molecules (CD28, CTLA-4, ICOS, PD-1) in patients with KT rejection and control KT patients without rejection. The Mann-Whitney U test, used for 2 groups, showed significant differences (P = .0005), indicating that PD-1 is underexpressed in patients with allograft rejection. No differences were found in CD28+, regulatory T cells (T reg), CTLA-4, and ICOS, so we are proposing that PD-1 is a key player in the immunotolerance phenomenon and its underexpression participates in the rejection process. More research needs to be performed on this topic.

New Markers for Transplant Rejection

Monitoring allograft function after kidney transplant has routinely relied on the use of nonspecific markers, such as serum creatinine, glomerular filtration rate, proteinuria, and donor-specific antibodies. These traditional markers have low sensitivity and fail to detect subclinical changes. Diagnosis of renal allograft dysfunction still requires an allograft biopsy, as it remains the criterion standard for assessment of graft status. However, renal biopsy is an invasive procedure, and sampling errors may result in misdiagnosis, perhaps causing graft failure. New biomarkers have been developed to monitor allograft function, although many are not yet routinely used. Other shortcomings, such as lack of standardization and high cost, should be solved before their widespread application in the clinic. A recipient's immune status could be monitored by use of urine or blood samples. These include functional cell-based assays and the evaluation of molecular expression at the messenger RNA or protein levels. Molecular technologies, including molecular microscope diagnostic systems, have been recently developed to improve the yield of histologic evaluation of the allograft biopsy. Prospective, interventional trials are required to demonstrate whether these new biomarkers improve patient or transplant outcomes. Implementation of these technologies into standard clinical practice remains challenging until their generalizability, cost, ease of interpretation, and the identification of patients who may benefit from more than standard-of-care surveillance can be determined. These biomarkers could allow immunosuppressive therapy to be individualized for patients.

Near-Infrared Spectroscopy Monitoring in Cardiac and Noncardiac Surgery: Pairwise and Network Meta-Analyses

Goal-directed therapy based on brain-oxygen saturation (bSo2) is controversial and hotly debated. While meta-analyses of aggregated data have shown no clinical benefit for brain near-infrared spectroscopy (NIRS)-based interventions after cardiac surgery, no network meta-analyses involving both major cardiac and noncardiac procedures have yet been undertaken. Randomized controlled trials involving NIRS monitoring in both major cardiac and noncardiac surgery were included. Aggregate-level data summary estimates of critical outcomes (postoperative cognitive decline (POCD)/postoperative delirium (POD), acute kidney injury, cardiovascular events, bleeding/need for transfusion, and postoperative mortality) were obtained. NIRS was only associated with protection against POCD/POD in cardiac surgery patients (pooled odds ratio (OR)/95% confidence interval (CI)/I2/number of studies (n): 0.34/0.14-0.85/75%/7), although a favorable effect was observed in the analysis, including both cardiac and noncardiac procedures. However, the benefit of the use of NIRS monitoring was undetectable in Bayesian network meta-analysis, although maintaining bSo2 > 80% of the baseline appeared to have the most pronounced impact. Evidence was imprecise regarding acute kidney injury, cardiovascular events, bleeding/need for transfusion, and postoperative mortality. There is evidence that brain NIRS-based algorithms are effective in preventing POCD/POD in cardiac surgery, but not in major noncardiac surgery. However, the specific target bSo2 threshold has yet to be determined.

Cholesterol-Lowering Treatment in Chronic Kidney Disease: Multistage Pairwise and Network Meta-Analyses

Pairwise and network meta-analyses on the relationship between the efficacy of the use of statins with or without ezetimibe and reductions in low-density lipoprotein cholesterol (LDLc) and C-reactive protein (CRP) in patients with chronic kidney disease (CKD) are presented. In the pairwise meta-analysis, statins with or without ezetimibe were shown to be efficacious in reducing major adverse cardiovascular events (MACE) in patients with CKD and an estimated glomerular filtration rate (eGFR) of less than 60 ml/min/1.73 m², in the context of both primary prevention [odds ratio (OR)/95% confidence interval (95% CI)/I²/number of studies (n): 0.50/0.40–0.64/0%/6] and primary/secondary prevention (0.66/0.57–0.76/57%/18). However, in the Bayesian network meta-analysis, compared to the placebo, only atorvastatin 80 mg daily and atorvastatin and rosuvastatin at doses equivalent to simvastatin 20 mg daily reduced the odds of MACEs in this patient population. The network meta-analysis for LDLc and CRP treatment objectives also showed that, regardless of eGFR and excluding dialysis patients, the number of MACEs decreased in patients with CKD, with reductions in both LDLc and CRP of less than 50% (surface under the cumulative ranking (SUCRA)/heterogeneity (vague)/n: 0.77/0.14/3). The evaluation of the benefits of drugs may lead to individualized therapy for CKD patients: Cholesterol-lowering treatment for CKD patients with high levels of both LDLc and CRP is suggested.

Data on a new biomarker for kidney transplant recipients: The number of FoxP3 regulatory T cells in the circulation

This article presents unrevealed details of the systematic review process of the article "The number of FoxP3 regulatory T cells in the circulation may be a predictive biomarker for kidney transplant recipients: A multistage systematic review" (Herrera-Gómez et al., 2018). Eligibility criteria guiding searches and study selection, the risk of bias assessment, the assessment of medicine-test codependency (evaluation of the body of evidence), and meta-analytic calculations are provided. The data allows other researchers, particularly those involved in experiments on Translational Epidemiology applied to Pharmacology, to corroborate and extend our assessments.