Elevated blood eosinophil count is a valuable biomarker for predicting late acute cellular rejection after liver transplantation

Solving the Conundrum of Eosinophils in Alloimmunity

Eosinophils are bone-marrow-derived granulocytes known for their ability to facilitate clearance of parasitic infections and their association with asthma and other inflammatory diseases. The purpose of this review is to discuss the currently available human observational and animal experimental data linking eosinophils to the immunologic response in solid organ transplantation. First, we present observational human studies that demonstrate a link between transplantation and eosinophils yet were unable to define the exact role of this cell population. Next, we describe published experimental models and demonstrate a defined mechanistic role of eosinophils in downregulating the alloimmune response to murine lung transplants. The overall summary of this data suggests that further studies are needed to define the role of eosinophils in multiple solid organ allografts and points to the possibility of manipulating this cell population to improve graft survival.

Peripheral blood eosinophilia as a marker of acute cellular rejection in lung transplant recipients

Previous studies in solid organ transplantation have shown a relationship between circulating eosinophil (EOS) counts and the presence of acute cellular rejection (ACR). However, the relationship between this potential biomarker and ACR in lung transplant (LTx) patients remains unclear.

OBJECTIVE

To assess the association between EOS and the presence of acute cellular rejection in lung transplant recipients.

MATERIALS AND METHODS

Retrospective study of 583 transbronchial biopsies (TBB) performed in 256 lung transplant patients between 2012 and 2018. We analyzed age, sex, underlying pathology, date of transplant, indications for TBB, presence and degree of ACR, and the simultaneous absolute and relative EOS.

RESULTS

ACR were observed in 170 of 583 TBB (29.2%). EOS in patients with ACR were higher than in patients without ACR (203.6 ± 248/mm³ vs 103.1 ± 153/mm³; p < 0.001). High levels of both absolute and relative EOS were associated with the presence of ACR regardless of the underlying disease (odds ratio [OR] 1.003; 95% confidence interval [CI], 1.002-1.004; OR 1.226; 95% CI, 1.120-1.342) and time after transplant (OR 1.003; 95% CI, 1.002-1.004 and OR 1.239; 95% CI, 1.132-1.356). Moreover, both absolute and relative EOS were strongly associated with moderate and severe grades of ACR (OR 3.55; 95% CI, 3.00-4.10 and OR 3.56; 95% CI, 3.00-4.12).

CONCLUSIONS

EOS are elevated in ACR, especially in moderate or severe ACR. Increased vigilance for ACR is therefore advisable in lung transplant recipients with elevated EOS.

Deciphering the role of eosinophils in solid organ transplantation

Eosinophils are rare granulocytes that belong to the innate arm of the immune system. This cell population is traditionally defined as a destructive and cytotoxic mediator in asthma and helminth infection. Limited data in transplantation have suggested that eosinophils play a similar role in potentiating deleterious organ inflammation and immunologic rejection. Contrary to this long-held notion, recent data have uncovered the possibility that eosinophils play an alternative role in immune homeostasis, defense against a wide range of pathogens, as well as downregulation of deleterious inflammation. Specifically, translational data from small animal models of lung transplantation have demonstrated a critical role for eosinophils in the downregulation of alloimmunity. These findings shed new light on the unique immunologic features of the lung allograft and demonstrate that environmental polarization may alter the phenotype and function of leukocyte populations previously thought to be static in nature. In this review, we provide an update on eosinophils in the homeostasis of the lung as well as other solid organs.

Eosinophil-to-monocyte ratio is an excellent predictor of acute cellular rejection in pancreas transplant alone recipients

Serum pancreatic enzymes (serum amylase and lipase) are sensitive markers for monitoring acute rejection in pancreatic transplant recipients. However, those enzymes are not specific, as their levels are elevated in other conditions. We evaluated the eosinophil-to-monocyte ratio (EMR) in peripheral blood as a biomarker of acute rejection in the clinical setting in recipients of pancreatic transplant alone. We performed 32 cases of pancreatic transplantation alone since 2015. Nine patients were diagnosed with rejection. Serum amylase and lipase levels and eosinophil and monocytes counts were analyzed and compared retrospectively between the non-rejection and rejection groups. The serum eosinophil count, eosinophil fraction of the complete blood count, and serum amylase and lipase levels were significant predictors of rejection according to the receiver operation characteristic (ROC) curve. However, the EMR was the best indicator of rejection based on the ROC curve (area under the curve 0.918, sensitivity 100%, specificity 76.2% at the cutoff value 0.80, P < .001). The combination of EMR and the lipase level had 100% sensitivity and 90.5% specificity. The EMR is a simple and excellent predictor of acute rejection in recipients of pancreatic transplant alone.

Diagnostic Biomarkers to Diagnose Acute Allograft Rejection After Liver Transplantation: Systematic Review and Meta-Analysis of Diagnostic Accuracy Studies

Objective: A systematic review and meta-analysis of diagnostic biomarkers for noninvasive diagnosis of acute allograft rejection following liver transplantation.

Background: Noninvasive blood and urine markers have been widely explored in recent decades for diagnosing acute rejection after liver transplantation. However, none have been translated into routine clinical use so far due to uncertain diagnostic accuracy, and liver biopsy remains the gold standard.

Methods: Systematic literature searches of Medline, Cochrane and Embase were conducted up to February 2019 to identify studies evaluating the use of noninvasive markers in diagnosing allograft rejection following liver transplantation. Meta-analysis was performed using a random effects model with DerSimonian–Laird weighting and the hierarchical summary receiver operating curve.

Results: Of 560 identified studies, 15 studies (1,445 patients) met the inclusion criteria. The following markers were tested: acid labile nitroso-compounds (NOx), serum amyloid A protein, procalcitonin, peripheral blood eosinophil count, peripheral blood T-cell activation and interleukin 2 (IL-2) receptor, guanylate-binding protein-2 mRNA, graft-derived cell-free DNA, pi-glutathione S-transferase, alpha-glutathione S-transferase and serum HLA class I soluble antigens. Only eosinophil count was tested in multiple studies, and they demonstrated high heterogeneity (I² = 72% [95% CI: 0.5–0.99]). IL-2 receptor demonstrated the highest sensitivity (89% [95% CI: 0.78–0.96]) and specificity (81% [95% CI: 0.69–0.89]).

Conclusion: IL-2 receptor expression demonstrated the highest diagnostic accuracy, while the peripheral eosinophil count was the only marker tested in more than one study. Presently, liver biopsy remains superior to noninvasive diagnostic biomarkers as most studies exhibited inferior designs, hindering possible translation into clinical application.

Impact of TBX21, GATA3, and FOXP3 gene polymorphisms on acute cellular rejection after liver transplantation

The single nucleotide polymorphisms (SNPs) rs4794067, rs2275806, rs2232365, and rs3761548 map in the genes of TBX21, GATA3, and FOXP3 involved in mediating acute cellular rejection. We investigated whether these SNPs are associated with acute cellular liver transplant rejection. The SNPs were analyzed in recipients with early acute cellular rejection (n = 97), recipients with late acute cellular rejection (n = 49), and recipients without rejection (n = 149). There was no association between acute cellular rejection and SNPs rs4794067, rs2275806, and rs2232365. In contrast, the allele -3279A of FOXP3 SNP rs3761548 exhibited a higher frequency in recipients with late acute cellular rejection as compared with recipients without rejection. This result indicates that the allele -3279A of the SNP rs3761548 may predispose to the development of late acute cellular rejection.

Alterations of Serum IP-10 and TARC in Patients with Early Acute Rejection after Liver Transplantation

Background/Aims: To analyze alterations of interferon-γ-induced protein 10 (IP-10) and thymus and activation-regulated chemokine (TARC) levels in early acute liver transplantation rejection. Methods: Thirty-six patients with early acute liver transplantation rejection were classified as non-, mild, moderate, and severe rejection groups. The levels of serum IP-10 and TARC were determined on days 3, 2, 1, and 0 before biopsy. Results: The IP-10 activities in all rejection groups were significantly higher (p < 0.05) than those in the non-rejection group at all time points and correlated with the extent of rejection (p < 0.05). The differences in TARC among the three rejection groups were significant (p < 0.05), and its highest level was found in the mild rejection group at all observed time points, whereas its lowest level was detected in the severe rejection group. The analysis of the TARC/IP-10 ratio revealed that the volume was correlated with the rejection degree. This ratio in the moderate and severe rejection groups on days 2, 1, and 0 before biopsy were 20% lower than that before transplantation. Conclusion: Serum IP-10 showed an increasing trend during early acute liver transplantation rejection. IP-10 increase or TARC/IP-10 ratio decrease combining with abnormal hepatic enzymatic alteration could be a valuable and specific sign for early rejection of the transplanted liver.

Late acute rejection in liver transplant: a systematic review

Introduction:

Late acute rejection leads to worse patient and graft survival after liver transplantation.

Aim:

To analyze the reported results published in recent years by leading transplant centers in evaluating late acute rejection and update the clinical manifestations, diagnosis and treatment of liver transplantation.

Method:

Systematic literature review through Medline-PubMed database with headings related to late acute rejection in articles published until November 2013 was done. Were analyzed demographics, immunosuppression, rejection, infection and graft and patient survival rates.

Results:

Late acute rejection in liver transplantation showed poor results mainly regarding patient and graft survival. Almost all of these cohort studies were retrospective and descriptive. The incidence of late acute rejection varied from 7-40% in these studies. Late acute rejection was one cause for graft loss and resulted in different outcomes with worse patient and graft survival after liver transplant. Late acute rejection has been variably defined and may be a cause of chronic rejection with worse prognosis. Late acute rejection occurs during a period in which the goal is to maintain lower immunosuppression after liver transplantation.

Conclusion:

The current articles show the importance of late acute rejection. The real benefit is based on early diagnosis and adequate treatment at the onset until late follow up after liver transplantation.