The Role of Fc Gamma Receptors in Antibody-Mediated Rejection of Kidney Transplants

For the past decades, complement activation and complement-mediated destruction of allograft cells were considered to play a central role in anti-HLA antibody-mediated rejection (AMR) of kidney transplants. However, also complement-independent mechanisms are relevant in the downstream immune activation induced by donor-specific antibodies, such as Fc-gamma receptor (FcγR)-mediated direct cellular activation. This article reviews the literature regarding FcγR involvement in AMR, and the potential contribution of FcγR gene polymorphisms to the risk for antibody mediated rejection of kidney transplants. There is large heterogeneity between the studies, both in the definition of the clinical phenotypes and in the technical aspects. The study populations were generally quite small, except for two larger study cohorts, which obviates drawing firm conclusions regarding the associations between AMR and specific FcγR polymorphisms. Although FcγR are central in the pathophysiology of AMR, it remains difficult to identify genetic risk factors for AMR in the recipient’s genome, independent of clinical risk factors, independent of the donor-recipient genetic mismatch, and in the presence of powerful immunosuppressive agents. There is a need for larger, multi-center studies with standardised methods and endpoints to identify potentially relevant FcγR gene polymorphisms that represent an increased risk for AMR after kidney transplantation.

Risk factors for acute kidney injury after pediatric cardiac surgery: a meta-analysis

BACKGROUND

Cardiac surgery-associated acute kidney injury (AKI) is associated with increased morbidity and mortality in both adults and children.

OBJECTIVES

This study aimed to identify clinical risk factors for AKI following cardiac surgery in the pediatric population.

DATA SOURCES

PubMed/MEDLINE, Embase, Scopus, and reference lists of relevant articles were searched for studies published by August 2020.

STUDY ELIGIBILITY CRITERIA

Studies were included if (1) the population consisted of pediatric patients (< 18 years old), (2) patients underwent cardiac surgery, (3) risk factors were compared between patients who developed AKI and those who did not, and (4) studies were prospective or retrospective observational studies or randomized controlled trials.

PARTICIPANTS AND INTERVENTIONS

Children undergoing pediatric cardiac surgery.

STUDY APPRAISAL AND SYNTHESIS METHODS

Random-effects meta-analysis was performed, comparing potential risk factors between pediatric patients who developed CS-AKI and those who did not.

RESULTS

Sixty-one publications including a total of 19,680 participants (AKI: 7257 participants; no AKI: 12,423 participants) were included from studies published between 2008 and 2020. The pooled estimated incidence of AKI was 34.3% (95% confidence interval 30.0-38.8%, I² = 96.8%). Binary risk factors that were significantly and consistently associated with AKI were the presence of pulmonary hypertension, cyanotic heart disease, univentricular heart, risk adjustment for congenital heart surgery 1 (RACHS-1) score ≥ 3, vasopressor use, cardiopulmonary bypass use, reoperation, and sepsis. Significant continuous risk factors included younger age, lower body weight, lower preoperative creatinine, higher preoperative estimated glomerular filtration rate (eGFR), higher RACHS-1 score, longer surgery time, longer cardiopulmonary bypass time, longer aortic cross-clamp time, and higher red blood cell transfusion volume.

LIMITATIONS

Results are limited by heterogeneity and potential residual confounding.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

Our meta-analysis identified clinical risk factors that are associated with AKI in children undergoing cardiac surgery. This might help clinicians anticipate and manage more carefully this population and implement standardized preventive strategies.

SYSTEMATIC REVIEW REGISTRATION NUMBER

CRD42021262699. A higher resolution version of the Graphical abstract is available as Supplementary information.