Mannose-binding lectin deficiency is not associated with increased risk for polyomavirus nephropathy

Innate Immunity Response to BK Virus Infection in Polyomavirus-Associated Nephropathy in Kidney Transplant Recipients

BK polyomavirus (BKV) mainly causes infection in uroepithelial and renal tubular epithelial cells of either immunocompetent or immunocompromised hosts. Despite asymptomatic or mild clinical features in immunocompetent hosts with BK infection, serious complications are frequently found in immunocompromised patients, especially patients with kidney transplantation. Accordingly, BKV-associated nephropathy (BKVN) demonstrates a wide range of clinical manifestations, including ureteric stenosis and hemorrhagic cystitis. In addition, BKV re-infection in post-kidney transplantation is also a main cause of kidney allograft dysfunction and graft loss. Since the direct anti-BKV is unavailable, immune response against BKV infection is the main mechanism for organism control and might be a novel strategy to treat or suppress BKV. As such, the innate immunity, consisting of immune cells and soluble molecules, does not only suppress BKV but also enhances the subsequent adaptive immunity to eradicate the virus. Furthermore, the re-activation of BKV in BKVN of kidney-transplanted recipients seems to be related to the status of innate immunity. Therefore, this review aims to collate the most recent knowledge of innate immune response against BKV and the association between the innate immunity status of kidney-transplanted recipients and BKV re-activation.

Predictive tools to determine risk of infection in kidney transplant recipients

Introduction: Infection represents a major complication after kidney transplantation (KT). Therapeutic drug monitoring is essentially the only approach for the adjustment of immunosuppression in current practice, with suboptimal results. The implementation of immune monitoring strategies may contribute to minimizing the risk of adverse events attributable to over-immunosuppression without compromising graft outcomes.Areas covered: The present review (based on PubMed/MEDLINE searches from database inception to November 2019) is focused on immune biomarkers with no antigen specificity (non-pathogen-specific), including serum levels of immunoglobulins and complement factors, peripheral blood lymphocyte subpopulations, soluble CD30, intracellular ATP production by stimulated CD4⁺ T-cells, and other cell-based immune assays. We also summarized recent advances in the use of replication kinetics of latent viruses to assess the functionality of T-cell immunity, with focus on the nonpathogenic anelloviruses. Finally, the composite risk scores reported in the literature are critically discussed.Expert opinion: Notable efforts have been made to develop an enlarging repertoire of immune biomarkers and prediction models, although most of them still lack technical standardization and external validation. Preventive interventions based on these tools (prolongation of prophylaxis, tapering of immunosuppression, or immunoglobulin replacement therapy in hypogammaglobulinemic patients) remain to be defined, ideally in the context of controlled trials.

Impact of MBL2 gene polymorphisms on the risk of infection in solid organ transplant recipients: A systematic review and meta-analysis

Mannose-binding lectin (MBL) is a soluble pattern recognition molecule involved in complement activation. Single nucleotide polymorphisms (SNPs) in the MBL2 gene have been associated with susceptibility to infection, although data in solid organ transplant recipients remains inconclusive. This meta-analysis was primarily aimed at investigating the association between posttransplant bacterial and fungal infection and variant alleles of MBL2 gene SNPs in the promoter/5' untranslated region and exon 1. Cytomegalovirus (CMV) infection and/or disease were considered secondary outcomes. PubMed, EMBASE, and Web of Knowledge were searched for relevant articles up to August 2018. Eleven studies (comprising 1858 patients) were included, with liver transplant (LT) recipients accounting for 80.4% of the pooled population. As compared to high-MBL expression haplotypes (YA/YA, YA/XA), any MBL-deficient haplotype was associated with an increased risk of posttransplant bacterial and fungal infections (risk ratio [RR]: 1.30; P = .04). Low/null-MBL expression haplotypes (XA/O, O/O) also increased the risk of primary outcome (RR: 1.51; P = .008) and CMV events (RR: 1.50; P = .006). No effect was observed for individual promoter SNPs. In conclusion, MBL-deficient haplotypes are associated with a significant, albeit moderate, increase in the risk of posttransplant infection, with this association being mainly restricted to LT recipients.

Mannose-Binding Lectin Levels in Critically Ill Children With Severe Infections

OBJECTIVES

Low mannose-binding lectin levels and haplotypes associated with low mannose-binding lectin production have been associated with infection and severe sepsis. We tested the hypothesis that mannose-binding lectin levels would be associated with severe infection in a large cohort of critically ill children.

DESIGN

Prospective cohort study.

SETTING

Medical and Surgical PICUs, Boston Children's Hospital.

PATIENTS

Children less than 21 years old admitted to the ICUs from November 2009 to November 2010.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We measured mannose-binding lectin levels in 479 of 520 consecutively admitted children (92%) with severe or life-threatening illness. We genotyped 213 Caucasian children for mannose-binding lectin haplotype tagging variants and assigned haplotypes. In the univariate analyses of mannose-binding lectin levels with preadmission characteristics, levels were higher in patients with preexisting renal disease. Patients who received greater than 100 mL/kg of fluids in the first 24 hours after admission had markedly lower mannose-binding lectin, as did patients who underwent spinal fusion surgery. Mannose-binding lectin levels had no association with infection status at admission, or with progression from systemic inflammatory response syndrome to sepsis or septic shock. Although mannose-binding lectin haplotypes strongly influenced mannose-binding lectin levels in the predicted relationship, low mannose-binding lectin-producing haplotypes were not associated with increased risk of infection.

CONCLUSIONS

Mannose-binding lectin levels are largely genetically determined. This relationship was preserved in children during critical illness, despite the effect of large-volume fluid administration on mannose-binding lectin levels. Previous literature evaluating an association between mannose-binding lectin levels and severe infection is inconsistent; we found no relationship in our PICU cohort. We found that mannose-binding lectin levels were lower after aggressive fluid resuscitation and suggest that studies of mannose-binding lectin in critically ill patients should assess mannose-binding lectin haplotypes to reflect preillness levels.

Innate Immunity and BK Virus: Prospective Strategies

Recent information demonstrated that BK virus reactivation is a dominant complication after kidney transplantation, which occurs because of immunosuppression. BK virus reactivation is the main reason of transplanted kidney losing. Immune response against BK virus is the major inhibitor of the virus reactivation. Therefore, improving our knowledge regarding the main parameters that fight against BK viruses can shed light on to direct new treatment strategies to suppress BK infection. Innate immunity consists of numerous cell systems and also soluble molecules, which not only suppress virus replication, but also activate adaptive immunity to eradicate the infection. Additionally, it appears that immune responses against reactivated BK virus are the main reasons for induction of BK virus-associated nephropathy (BKAN). Thus, improving our knowledge regarding the parameters and detailed mechanisms of innate immunity and also the status of innate immunity of the patients with BK virus reactivation and its complications can introduce new prospective strategies to either prevent or as therapy of the complication. Therefore, this review was aimed to collate the most recent data regarding the roles played by innate immunity against BK virus and also the status of innate immunity in the patients with reactivation BK virus and BKAN.