Mannose-binding lectin and ficolin-2 gene polymorphisms predispose to cytomegalovirus (re)infection after orthotopic liver transplantation

Polygenic Innate Immunity Score to Predict the Risk of Cytomegalovirus Infection in CMV D+/R- Transplant Recipients. A Prospective Multicenter Cohort Study

Several genetic polymorphisms of the innate immune system have been described to increase the risk of cytomegalovirus (CMV) infection in transplant patients. The aim of this study was to assess the impact of a polygenic score to predict CMV infection and disease in high risk CMV transplant recipients (heart, liver, kidney or pancreas). On hundred and sixteen CMV-seronegative recipients of grafts from CMV-seropositive donors undergoing heart, liver, and kidney or pancreas transplantation from 7 centres were prospectively included for this purpose during a 2-year period. All recipients received 100-day prophylaxis with valganciclovir. CMV infection occurred in 61 patients (53%) at 163 median days from transplant, 33 asymptomatic replication (28%) and 28 CMV disease (24%). Eleven patients (9%) had recurrent CMV infection. Clinically and/or functionally relevant single nucleotide polymorphisms (SNPs) from TLR2, TLR3, TLR4, TLR7, TLR9, AIM2, MBL2, IL28, IFI16, MYD88, IRAK2 and IRAK4 were assessed by real time polymerase chain reaction (RT-PCR) or sequence-based typing (PCR-SBT). A polygenic score including the TLR4 (rs4986790/rs4986791), TLR9 (rs3775291), TLR3 (rs3775296), AIM2 (rs855873), TLR7 (rs179008), MBL (OO/OA/XAO), IFNL3/IL28B (rs12979860) and IFI16 (rs6940) SNPs was built based on the risk of CMV infection and disease. The CMV score predicted the risk of CMV disease with an AUC of the model of 0.68, with sensitivity and specificity of 64.3 and 71.6%, respectively. Even though further studies are needed to validate this score, its use would represent an effective model to develop more robust scores predicting the risk of CMV disease in donor/recipient mismatch (D+/R-) transplant recipients.

Cytomegalovirus infection in liver-transplanted children

Cytomegalovirus (CMV) infection is a common complication of liver trans-plantation in children. The CMV serostatus of recipients and donors is the primary risk factor, and prophylaxis or pre-emptive strategies are recommended for high-risk patients. Graft rejection, coinfection and Epstein-Bar virus reactivation, which can lead to post-transplant lymphoproliferative disease, are indirect effects of CMV infection. Assessment of CMV infection viral load should be routinely performed upon clinical suspicion. However, tissue-invasive CMV disease is not associated with CMV viraemia and requires confirmation by tissue pathology. Oral valganciclovir and intravenous ganciclovir are equivalent treatments, and the duration of treatment depends on factors including CMV viral load, tissue pathology, and clinical response. Risk stratification by donor and recipient status prior to transplantation and post-transplantation antiviral prophylaxis or pre-emptive therapy are recommended. Adult guidelines have been established but additional study of the effectiveness of the preventive guidelines in children is needed. This review summarizes the burden, risk factors, clinical manifestations, laboratory evaluation, treatment, and prevention of CMV infection in children after liver transplantation.

The role of complement activation in autoimmune liver disease

INTRODUCTION

The complement system, an essential part of the innate immune system, is involved in various autoimmune diseases. Activation of the complement system by autoantibodies results in immune activation and tissue damage. At the moment little is known about the role of the complement system in autoimmune liver disease, including primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC) and autoimmune hepatitis (AIH). Since inhibition of the complement system is currently being tested in several autoimmune diseases as a therapeutic option, its role in autoimmune liver disease requires further clarification.

METHODS

A review of the literature was performed on studies investigating complement activation in PBC, PSC and AIH. Since data on AIH were lacking immunohistochemical staining for IgG, C1q, C3d, C4d and C5b9 was performed on liver tissue of nine AIH patients, two healthy controls and one positive control (acute liver failure caused by paracetamol intoxication).

RESULTS

Immunohistochemical analysis in AIH revealed increased production of C3 and C4 by hepatocytes. Despite a strong staining for IgG in the immune infiltrate in AIH, C3d, C4d and C5b9 deposition was only present in one AIH patient and the deposition was restricted to the interface between portal tracts and liver parenchyma. No deposition was found in all other AIH patients or healthy controls. Literature review showed raised plasma C3 and C4 levels in AIH, PBC and PSC patients compared to healthy controls. For PBC and PSC no complement depositions at the bile ducts were reported.

CONCLUSION AND DISCUSSION

Although complement is involved in various autoimmune diseases, the role of complement in autoimmune liver disease seems limited. Therefore it is unlikely that complement inhibition will become a novel treatment option for these diseases.

Genetic variants of innate immunity receptors are associated with mortality in cirrhotic patients with bacterial infection

BACKGROUND & AIMS

Acute-on-chronic liver failure (ACLF) is characterized by acute decompensation of cirrhosis (AD), organ failure(s) and high risk of short-term mortality with bacterial infection frequently as precipitating event. Innate immune pattern recognition receptors and members of the lectin pathway of complement activation are crucial to the innate immune response to pathogens. The aim of this study was to investigate whether single nucleotide polymorphisms (SNPs) of innate immune components are associated with the occurrence of bacterial infections or mortality in patients with cirrhosis hospitalized for AD or ACLF.

METHODS

Twenty-one innate immunity SNPs with known functional implications were genotyped in 826 AD/ACLF patients included in the CANONIC study. Associations between baseline characteristics of the patients, the occurrence of bacterial infections and survival rate at 90 days of follow-up in relation to the innate immunity genetic variants were analysed.

RESULTS

The NOD2-G908R genetic variant was associated with mortality (HR 2.25, P = .004) independently of age and MELD Score. This association was also found in a predefined subgroup analysis in patients with bacterial infections (HR 2.78, P < .001) along with MBL_Yx (HR 1.72, P = .008) and MASP2_371 (HR 1.67, P = .012) genetic variants. None of the analysed SNPs were significantly associated with the occurrence of acute bacterial infections or spontaneous bacterial peritonitis in particular.

CONCLUSIONS

Innate immune system-specific NOD2-G908R, MBL_Yx and MASP2_371 genetic variants were independently associated with increased risk of short-term mortality in AD/ACLF patients with bacterial infection.

IL28B rs12979860 T allele protects against CMV disease in liver transplant recipients in the post-prophylaxis and late period

BACKGROUND

Cytomegalovirus (CMV) disease represents a serious complication in liver transplant (OLT) recipients. CMV prophylaxis reduces incidence of CMV disease in the early post-transplant period (on-prophylaxis disease, OPD) but may postpone its manifestation after the completion of prophylaxis. Post-prophylaxis disease (PPD) incidence after prophylaxis cessation may be modified by genetic factors.

METHODS

We analyzed impact of IL28B rs1297986 variants on CMV disease incidence in 743 adult OLT recipients receiving universal prophylaxis.

RESULTS

One hundred and forty-four (19.4%) patients had at least one CMV disease episode. One hundred and two of them (70.8%) had at least one OPD and 36 (25%) patients had PPD, six (4.2%) patients had both. The rate of IL28B T allele carriers was lower in PPD group (38.9%) in comparison with OPD group (66.7%, P = 0.005) and group without CMV disease (61.4%, P = 0.009). The impact of IL28B genotype on the risk of CMV OPD was significant neither in the allelic (TT + CT vs CC, P = 0.32) nor in the recessive model (TT vs CT + CC, P = 0.79). Contrarily, in the PPD group, T allele (TT + CT vs CC) had a protective effect, OR 0.4 (95% CI 0.2-0.8, P = 0.008). Further risk factors of PPD were age <55 years and valganciclovir prophylaxis, whereas the risk factors of OPD were age <55 years, cyclosporine A therapy and pre-transplant CMV serostatus (donor +/recipient -).

CONCLUSIONS

IL28B rs12979860 T allele carriers had a lower risk of CMV PPD.

New Developments in the Management of Cytomegalovirus Infection After Transplantation

Cytomegalovirus (CMV) continues to be one of the most important pathogens that universally affect solid organ and allogeneic hematopoietic stem cell transplant recipients. Lack of effective CMV-specific immunity is the common factor that predisposes to the risk of CMV reactivation and clinical disease after transplantation. Antiviral drugs are the cornerstone for prevention and treatment of CMV infection and disease. Over the years, the CMV DNA polymerase inhibitor, ganciclovir (and valganciclovir), have served as the backbone for management, while foscarnet and cidofovir are reserved for the management of CMV infection that is refractory or resistant to ganciclovir treatment. In this review, we highlight the role of the newly approved drug, letermovir, a viral terminase inhibitor, for CMV prevention after allogeneic hematopoietic stem cell transplantation. Advances in immunologic monitoring may allow for an individualized approach to management of CMV after transplantation. Specifically, the potential role of CMV-specific T-cell measurements in guiding the need for the treatment of asymptomatic CMV infection and the duration of treatment of CMV disease is discussed. The role of adoptive immunotherapy, using ex vivo-generated CMV-specific T cells, is highlighted. This article provides a review of novel drugs, tests, and strategies in optimizing our current approaches to prevention and treatment of CMV in transplant recipients.

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.

The Third International Consensus Guidelines on the Management of Cytomegalovirus in Solid-organ Transplantation

Despite recent advances, cytomegalovirus (CMV) infections remain one of the most common complications affecting solid organ transplant recipients, conveying higher risks of complications, graft loss, morbidity, and mortality. Research in the field and development of prior consensus guidelines supported by The Transplantation Society has allowed a more standardized approach to CMV management. An international multidisciplinary panel of experts was convened to expand and revise evidence and expert opinion-based consensus guidelines on CMV management including prevention, treatment, diagnostics, immunology, drug resistance, and pediatric issues. Highlights include advances in molecular and immunologic diagnostics, improved understanding of diagnostic thresholds, optimized methods of prevention, advances in the use of novel antiviral therapies and certain immunosuppressive agents, and more savvy approaches to treatment resistant/refractory disease. The following report summarizes the updated recommendations.

Going beyond serology for stratifying the risk of CMV infection in transplant recipients

Knowledge of donor and recipient (D/R) cytomegalovirus (CMV) serostatus is critical for risk stratification of CMV infection and disease in transplant recipients, particularly in the solid organ transplantation (SOT) setting. Despite its broad availability and the success of it use, the risk stratification based on the D/R serostatus is not free of limitations since there are a nondepreciable number of patients that are not accurately categorized by this approach. In fact, up to 20% of seropositive SOT recipients, classically considered at intermediate risk, develop episodes of CMV infection and disease after transplantation. Here, we provide an overview of additional donor and recipient factors that may have utility in identifying patients at risk for post-transplant CMV infection. Specifically, we summarize our current understanding regarding the potential use of use CMV-specific T-cell-mediated immunity, neutralizing antibodies and host genetics that may influence the risk of CMV infection and disease. We provide an overview of the benefits and limitations associated with using these immunological factors in risk stratification and propose specific variables that could be analyzed at the pretransplant evaluation to improve the identification of patients with increased individual susceptibility.

Ficolin-2 Gene rs7851696 Polymorphism is Associated with Delayed Graft Function and Acute Rejection in Kidney Allograft Recipients

Ficolin-2 is an activator of the complement system that acts via the lectin pathway. Complement activation plays a substantial role in the renal injury inherent to kidney transplantation. In this study, we examined the associations between ficolin-2 gene polymorphisms in exon 8 and kidney allograft function. This study comprised 270 Caucasian deceased-donor renal transplant recipients. The following parameters were recorded in each case: delayed graft function (DGF), acute rejection (AR), and chronic allograft dysfunction. Among patients with DGF, we observed a significantly increased frequency of rs7851696 GT and TT genotypes as well as T allele (TT + GT vs GG OR 1.98, 95% CI 1.12-3.48, p = 0.02; T vs G OR 2.08, 95% CI 1.27-3.41, p = 0.005). There was also an increased frequency of rs4521835 GG and TG genotypes as well as G alleles; however, these differences were on the borderline of statistical significance (GG + TG vs TT, OR 1.75, 95% CI 0.98-3.12, p = 0.07; G vs T OR 1.45, 95% CI 1.00-2.09, p = 0.050). In addition, we observed an increased frequency of acute allograft rejection in carriers of ficolin-2 rs7851696 T alleles on the borderline of statistical significance (TT + GT vs GG OR 1.75, 95% CI 0.97-3.16, p = 0.08), but the frequency of T allele was significantly higher in patients with AR (T vs G OR 1.71, 95% CI 1.02-2.87, p = 0.048). The results of our study suggest that ficolin-2 rs7851696 gene polymorphism influences kidney allograft functions, with T allele increasing the risk of DGF and AR.

Mannose-Binding Lectin-Deficient Donors Increase the Risk of Bacterial Infection and Bacterial Infection-Related Mortality After Liver Transplantation

Mannose-binding lectin (MBL) is synthesized by the liver and binds to microbes. MBL2 gene polymorphisms produce intermediate/low/null or normal MBL serum levels (MBL-deficient or MBL-sufficient phenotypes, respectively). We aimed to evaluate the incidence and severity of infection, rejection, and survival within 1 year after liver transplantation (LT) according to donor and recipient MBL2 gene polymorphisms. A repeated-event analysis for infection episodes (negative binomial regression, Andersen-Gill model) was performed in 240 LTs. Four hundred twenty-eight infectious episodes (310 bacterial, 15 fungal, 65 cytomegalovirus [CMV]-related, and 38 viral non-CMV-related episodes) and 48 rejection episodes were recorded. The main bacterial infections were urinary (n = 82, 26%) and pneumonia (n = 69, 22%). LT recipients of MBL-deficient livers had a higher risk of bacterial infection (incidence rate ratio [IRR] 1.48 [95% confidence interval 1.04-2.09], p = 0.028), pneumonia (IRR 2.4 [95% confidence interval 1.33-4.33], p = 0.013), and septic shock (IRR 5.62 [95% confidence interval 1.92-16.4], p = 0.002) compared with recipients of MBL-deficient livers. The 1-year bacterial infection-related mortality was higher in recipients of MBL-deficient versus MBL-sufficient livers (65.8% vs. 56.1%, respectively; p = 0.0097). The incidence of rejection, viral, or fungal infection was similar in both groups. Recipient MBL2 genotype did not significantly increase the risk of bacterial infection. LT recipients of MBL-deficient livers have a higher risk of bacterial infection, pneumonia, septic shock, and 1-year bacterial infection-related mortality after LT.

FCN2 c.772G>T polymorphism is associated with chronic adenoiditis and/or tonsillitis, but not -4 A>G and -602 G>A

OBJECTIVE

Ficolins are complement activating peptides that play a role in the initial host defense against infectious pathogens. In the present study, we investigated the relationship between single nucleotide polymorphisms (SNPs) in the ficolin 2 gene (FCN2) and chronic adenotonsillitis in pediatric cases.

STUDY DESIGN

Case-control study.

METHODS

A total of 101 pediatric patients diagnosed with chronic adenotonsillitis and 100 healthy children were enrolled in the study. Genotypes of FCN2 promoter SNPs - 602 G>A and -4 A>G, and the exonic SNP c.772G>T were determined by light SNP assay after realtime PCR analysis using genomic DNA samples obtained from peripheral blood samples of all participants.

RESULTS

Of the 101 chronic tonsillitis patients, 38 were girls and 63 were boys; the mean age was 5.2 ± 2.3 years. The c.772G>T SNP frequency was significantly higher in chronic adenotonsillitis cases compared to the control group (p = 0.00); however, no significant difference was determined at positions -602 G>A or -4 A>G (p > 0.05).

CONCLUSIONS

The FCN2 c.772G>T genotype appears to be associated with predisposition to chronic adenotonsillitis in the pediatric age group. This nucleotide change is likely to influence the level of gene expression and contribute to the development of disease.

Mannan-binding lectin reduces CpG DNA-induced inflammatory cytokine production by human monocytes

Mannan-binding lectin (MBL) belongs to the collectin family and functions as an opsonin that can also initiate complement activation. Our previous study showed that MBL serves as a double-stranded RNA binding protein that attenuates polyriboinosinic-polyribocytidylic acid-induced TLR3 activation. Prompted by these findings, in the present study cross-talk between MBL and CpG-DNA-induced TLR9 activation was investigated. Here, it was found that MBL also interacts with the TLR9 agonist, CpG oligodeoxynucleotide (CpG-ODN), in a calcium-dependent manner. Purified MBL protein suppressed activation of nuclear factor-kappa B signaling and subsequent production of proinflammatory cytokines from human monocytes induced by CpG-ODN 2006. These observations indicate that MBL can down-regulate CpG DNA-induced TLR9 activation, emphasizing the importance of understanding the interaction of MBL with TLR agonist in host immune defense.

Association between individual and combined SNPs in genes related to innate immunity and incidence of CMV infection in seropositive kidney transplant recipients

In this study, we assessed the association between single-nucleotide polymorphisms (SNPs) in seven candidate genes involved in orchestrating the immune response against cytomegalovirus (CMV) and the 12-month incidence of CMV infection in 315 CMV-seropositive kidney transplant (KT) recipients. Patients were managed either by antiviral prophylaxis or preemptive therapy. CMV infection occurred in 140 patients (44.4%), including 13 episodes of disease. After adjusting for various clinical covariates, patients harboring T-allele genotypes of interleukin-28B (IL28B) (rs12979860) SNP had lower incidence of CMV infection (adjusted hazard ratio [aHR]: 0.66; 95% confidence interval [CI]: 0.46-0.96; p-value = 0.029). In the analysis restricted to patients not receiving prophylaxis, carriers of the TT genotype of toll-like receptor 9 (TLR9) (rs5743836) SNP had lower incidence of infection (aHR: 0.61; 95% CI: 0.38-0.96; p-value = 0.035), whereas the GG genotype of dendritic cell-specific ICAM 3-grabbing nonintegrin (DC-SIGN) (rs735240) SNP exerted the opposite effect (aHR: 1.86; 95% CI: 1.18-2.94; p-value = 0.008). An independent association was found between the number of unfavorable SNP genotypes carried by the patient and the incidence of CMV infection. In conclusion, specific SNPs in IL28B, TLR9 and DC-SIGN genes may play a role in modulating the susceptibility to CMV infection in CMV-seropositive KT recipients.

New insights into the role of ficolins in the lectin pathway of innate immunity

In the innate immune system, a variety of recognition molecules provide the first-line host defense to prevent infection and maintain endogenous homeostasis. Ficolin is a soluble recognition molecule, which senses pathogen-associated molecular patterns on microbes and aberrant sugar structures on self-cells. It consists of a collagen-like stalk and a globular fibrinogen-like domain, the latter binding to carbohydrates such as N-acetylglucosamine. Ficolins have been widely identified in animals from higher invertebrates to mammals. In mammals, ficolins form complexes with mannose-binding lectin-associated serine proteases (MASPs), and ficolin-MASP complexes trigger complement activation via the lectin pathway. Once activated, complement mediates many immune responses including opsonization, phagocytosis, and cytokine production. Although the precise function of each ficolin is still under investigation, accumulating information suggests that ficolins have a crucial role in host defense by recognizing a variety of microorganisms and interacting with effector proteins.

Human lectins and their roles in viral infections

Innate recognition of virus proteins is an important component of the immune response to viral pathogens. A component of this immune recognition is the family of lectins; pattern recognition receptors (PRRs) that recognise viral pathogen-associated molecular patterns (PAMPs) including viral glycoproteins. In this review we discuss the contribution of soluble and membrane-associated PRRs to immunity against virus pathogens, and the potential role of these molecules in facilitating virus replication. These processes are illustrated with examples of viruses including human immunodeficiency virus (HIV), hepatitis C virus (HCV) and Ebola virus (EBOV). We focus on the structure, function and genetics of the well-characterised C-type lectin mannose-binding lectin, the ficolins, and the membrane-bound CD209 proteins expressed on dendritic cells. The potential for lectin-based antiviral therapies is also discussed.

Genetic variants of innate immune receptors and infections after liver transplantation

Infection is the leading cause of complication after liver transplantation, causing morbidity and mortality in the first months after surgery. Allograft rejection is mediated through adaptive immunological responses, and thus immunosuppressive therapy is necessary after transplantation. In this setting, the presence of genetic variants of innate immunity receptors may increase the risk of post-transplant infection, in comparison with patients carrying wild-type alleles. Numerous studies have investigated the role of genetic variants of innate immune receptors and the risk of complication after liver transplantation, but their results are discordant. Toll-like receptors and mannose-binding lectin are arguably the most important studied molecules; however, many other receptors could increase the risk of infection after transplantation. In this article, we review the published studies analyzing the impact of genetic variants in the innate immune system on the development of infectious complications after liver transplantation.

Restoration of MBL-deficiency: redefining the safety, efficacy and viability of MBL-substitution therapy

MBL-deficiency is a commonly occurring deficiency of the innate immune system, affecting a substantial part of the population and has been extensively studied. MBL appears to function as a disease modifier. The role of MBL in different conditions is context-dependent. Many clinical studies show conflicting results, which can be partially explained by different definitions of MBL-deficiency, including phenotype- and genotype-based approaches. In this review we give an overview of literature of MBL, its role in different pathologies, diseases and patient populations. We review MBL replacement studies, and discuss the potential of MBL substitution therapy. We finally suggest that new MBL substitution trials should be conducted within a predefined patient population. MBL-deficiency should be based on serum levels and confirmed by genotyping.

The lectin pathway of complement: advantage or disadvantage in HIV pathogenesis?

The pattern recognition molecules of the lectin complement pathway are important components of the innate immune system with known functions in host-virus interactions. This paper summarizes current knowledge of how these intriguing molecules, including mannose-binding lectin (MBL), Ficolin-1, -2 and -3, and collectin-11 (CL-11) may influence HIV-pathogenesis. It has been demonstrated that MBL is capable of binding and neutralizing HIV and may affect host susceptibility to HIV infection and disease progression. In addition, MBL may cause variations in the host immune response against HIV. Ficolin-1, -2 and -3 and CL-11 could have similar functions in HIV infection as the ficolins have been shown to play a role in other viral infections, and CL-11 resembles MBL and the ficolins in structure and binding capacity.

Mannose binding lectin and ficolin-2 polymorphisms are associated with increased risk for bacterial infections in children with B acute lymphoblastic leukemia

BACKGROUND

We aimed to investigate whether the presence of mannose binding lectin (MBL2), ficolin 2 (FCN2) polymorphisms or the combined deficiency significantly influence the risk and subsequently the frequency of chemotherapy-induced bacterial infections in children with B acute lymphoblastic leukemia (B-ALL).

PROCEDURE

MBL2 polymorphisms for exon 1 and FCN2 polymorphisms for promoter regions -986, -602, -557, -64, -4 and exon 8 regions +6,359, +6,424 were determined in children with B-ALL. FCN2 haplotype was determined by gene sequencing. Number and duration of FN episodes as well as number of bacterial infections were recorded during induction chemotherapy.

RESULTS

Forty-four children with B-ALL (median age 4.3 years, 65.9% males) suffered from 142 FN episodes and 92 bacterial infections (40.2% Gram positive and 59.8% Gram negative). MBL2 low-risk genotype was found in 59.1%, medium-risk in 31.8% and high-risk in 9%. FCN2 low-risk haplotypes were detected in 38.2%, medium-risk in 44.1% and high-risk in 17.6%. MBL2 genotype and FCN2 haplotype were not associated with increased frequency of FN episodes. MBL2 medium/high-risk genotype and FCN2 medium/high-risk haplotype were associated with prolonged duration of FN (P = 0.007 and P = 0.001, respectively) and increased number of bacterial infections (P = 0.001 and P = 0.002, respectively). The combined MBL2/FCN2 medium/high-risk genotype was associated with an increased number of bacterial infections (P = 0.001).

CONCLUSIONS

MBL2 and FCN2 single or combined deficiencies are associated with increased duration of FN episodes as well as increased number of bacterial infections in children with B-ALL suggesting a prognostic role of these genes.

Risk of infection and sepsis in severely injured patients related to single nucleotide polymorphisms in the lectin pathway

BACKGROUND

Infectious complications remain a serious threat to patients with multiple trauma. Susceptibility and response to infection is, in part, heritable. The lectin pathway plays a major role in innate immunity. The aim of this study was to assess whether single nucleotide polymorphisms (SNPs) in three key genes within the lectin pathway affect susceptibility to infectious complications in severely injured patients.

METHODS

A prospective cohort of severely injured patients admitted to a level I trauma centre between January 2008 and April 2011 were genotyped for SNPs in MBL2 (mannose-binding lectin 2), MASP2 (MBL-associated serine protease 2) and FCN2 (ficolin 2). Association of genotype with prevalence of positive culture findings and infection was tested by χ(2) and logistic regression analysis.

RESULTS

A total of 219 patients were included, of whom 112 (51·1 per cent) developed a positive culture from sputum, wounds, blood or urine. A systemic inflammatory response syndrome (SIRS) developed in 139 patients (63·5 per cent), sepsis in 79 (36·1 per cent) and septic shock in 37 (16·9 per cent). Patients with a MBL2 exon 1 variant allele were more prone to positive wound cultures (odds ratio (OR) 2·51, 95 per cent confidence interval 1·12 to 5·62; P = 0·025). A MASP2 Y371D DD genotype predisposed to SIRS (OR 4·78, 1·06 to 21·59; P = 0·042) and septic shock (OR 2·53, 1·12 to 4·33; P = 0·003). A FCN2 A258S AS genotype predisposed to positive wound cultures (OR 3·37, 1·45 to 7·85; P = 0·005) and septic shock (OR 2·18, 1·30 to 4·78; P = 0·011).

CONCLUSION

Severely injured patients with SNPs in MBL2, MASP2 Y371D and FCN2 A258S of the lectin pathway of complement activation are significantly more susceptible to positive culture findings, and to infectious complications, SIRS and septic shock than patients with a wildtype genotype.

Updated international consensus guidelines on the management of cytomegalovirus in solid-organ transplantation

Cytomegalovirus (CMV) continues to be one of the most common infections after solid-organ transplantation, resulting in significant morbidity, graft loss, and adverse outcomes. Management of CMV varies considerably among transplant centers but has been become more standardized by publication of consensus guidelines by the Infectious Diseases Section of The Transplantation Society. An international panel of experts was reconvened in October 2012 to revise and expand evidence and expert opinion-based consensus guidelines on CMV management, including diagnostics, immunology, prevention, treatment, drug resistance, and pediatric issues. The following report summarizes the recommendations.

Swierzko A, Cedzynski M. Cost-effective procedures for genotyping of human FCN2 gene single nucleotide polymorphisms

L-ficolin (ficolin-2) is a complement-activating pattern-recognition lectin taking part in the innate immune response. Both its serum concentration and sugar binding capacity are influenced by single nucleotide polymorphisms (SNP) of the corresponding FCN2 gene. Cost-effective and simple procedures, based on polymerase chain reaction (PCR) or PCR-restriction fragment length polymorphism for an investigation of four FCN2 SNPs are proposed: -64 A > C (rs7865453), -4 A > G (rs17514136; both located in the promoter region), +6359 C > T (rs17549193), +6424 G > T (rs7851696; both in exon 8). Variant alleles of -64 and +6424 (in strong linkage disequlibrium) are known to be associated with low L-ficolin level or activity. In contrast, variant alleles at positions -4 and +6359 (also in strong linkage disequlibrium) correspond to higher values. Since several L-ficolin clinical associations have been reported, FCN2 genotyping seems to be a valuable tool for disease association studies.

Association of L-ficolin levels and FCN2 genotypes with chronic Chagas disease

BACKGROUND

L-ficolin (encoded by FCN2) binds to acetylated sugar moieties of many pathogens, including Trypanosoma cruzi, promoting their phagocytosis and lysis by the complement system.

METHODS

We investigated L-ficolin levels in 160 T. cruzi infected patients with chronic Chagas disease and 71 healthy individuals, and FCN2 polymorphisms (-986 G>A, -602 G>A, and -4 A>G in the promoter and A258S in exon 8) in 243 patients, being 88 indeterminate (asymptomatic), 96 with cardiac, 23 with digestive and 33 with cardiodigestive manifestations (two were unspecified) and 305 controls (135 for A258S).

RESULTS

Patients presented lower L-ficolin plasma levels than controls (p<0.0001). Among the different groups of cardiac commitment, individuals with moderate forms had higher L-ficolin levels than the severe forms (P = 0.039). Lower L-ficolin levels were found associated with the 258S variant in the patients (P = 0.034). We found less -4A/G heterozygotes in the cardiac patients, than in the controls (OR = 0.56 [95% CI = 0.33-0.94], P = 0.034). Heterozygote -4A/G genotypes with the 258S variant and 258SS homozygotes were nevertheless more frequent among cardiodigestive patients than in controls (OR = 14.1 [95% CI = 3.5-56.8], P = 0.0001) and in indeterminate patients (OR = 3.2 [95% CI = 1.1-9.4], P = 0.037). We also found an association of the allelic frequency of the 258S variant with cardiodigestive Chagas disease compared to controls (OR = 2.24 [95% CI = 1.1-4.5], P = 0.037). Thus, decreased patient levels of L-ficolin reflect not only protein consumption due to the disease process, but also the higher frequency of the 258S variant in patients with cardiodigestive symptoms.

CONCLUSION

The very first study on Brazilian cohort associates both L-ficolin plasma levels and FCN2 variants to Chagas disease and subsequent disease progression. The prognostic value of L-ficolin levels and the FCN2*A258S polymorphism should be further evaluated in other settings.

Management strategies for cytomegalovirus infection and disease in solid organ transplant recipients

Cytomegalovirus is the most common viral pathogen that affects solid organ transplant recipients. It directly causes fever, myelosuppression, and tissue-invasive disease, and indirectly, it negatively impacts allograft and patient survival. Nucleic acid amplification testing is the preferred method to confirm the diagnosis of CMV infection. Prevention of CMV disease using antiviral prophylaxis or preemptive therapy is critical in the management of transplant patients. Intravenous ganciclovir and oral valganciclovir are the first line drugs for antiviral treatment. This article provides a comprehensive review of the current epidemiology, diagnosis, prevention and treatment of CMV infection in solid organ transplant recipients.

Mannose binding lectin (mbl2) haplotype frequencies in solid organ transplant patients and correlation with MBL protein levels--evaluation of complement-mediated effector pathway deficiency

Mannose-binding lectin (MBL) is a protein critical in activating complement. Patients with wild-type and variant mbl2 genotypes have high or low concentrations of MBL protein, which is known to increase susceptibility to transplant rejection or infection, respectively. Our objective was to determine mbl2 genotype frequencies in future solid organ transplant recipients in order to optimize their induction and maintenance immunosuppressive therapies, and to provide MBL reference data for this unique population. We genotyped 1687 patients, and concurrently measured protein in 807 of them, during 2010-2011. Frequencies of the structural allele SNPs in our population were similar to those of other studied populations; however, Black patients with the same intermediate and deficient mbl2 genotypes as Caucasians produced significantly lower levels of MBL protein; therefore, within this population more genotypes should be considered MBL-deficient. Overall, the most critical parameter in determining serum MBL protein concentration was genotype, which was independent of other factors including ethnicity, gender, or diseased native organ type.

Low levels of mannan-binding lectin or ficolins are not associated with an increased risk of cytomegalovirus disease in HIV-infected patients

BACKGROUND

In HIV-infected patients, prediction of Cytomegalovirus (CMV) disease remains difficult. A protective role of mannan-binding lectin (MBL) and ficolins against CMV disease has been reported after transplantation, but the impact in HIV-infected patients is unclear.

METHODS

In a case-control study nested within the Swiss HIV Cohort Study, we investigated associations between plasma levels of MBL/ficolins and CMV disease. We compared HIV-infected patients with CMV disease (cases) to CMV-seropositive patients without CMV disease (controls) matched for CD4 T-cells, sampling time, and use of combination antiretroviral therapy. MBL and M-ficolin, L-ficolin, and H-ficolin were quantified using ELISA.

RESULTS

We analysed 105 cases and 105 matched controls. CMV disease was neither associated with MBL (odds ratio [OR] 1.03 per log(10) ng/mL increase (95% CI 0.73-1.45)) nor with ficolins (OR per log(10) ng/mL increase 0.66 (95% CI 0.28-1.52), 2.34 (95% CI 0.44-12.36), and 0.89 (95% CI 0.26-3.03) for M-ficolin, L-ficolin, and H-ficolin, respectively). We found no evidence of a greater association between MBL and CMV disease in patients with low CD4 counts; however in the multivariable analysis, CMV disease was more likely in patients with an increased HIV RNA (OR 1.53 per log(10) copies/mL; 95% CI 1.08-2.16), or a shorter duration of HIV-infection (OR 0.91 per year; 95% CI 0.84-0.98).

CONCLUSIONS

CMV disease is not associated with low levels of MBL/ficolins, suggesting a lack of a protective role in HIV-infected patients.

[Risk factors for cytomegalovirus in solid organ transplant recipients]

Cytomegalovirus (CMV) is the most important opportunistic pathogen in patients undergoing solid organ transplantation and increases mortality due to both direct and indirect effects. The most important risk factor for the development of CMV disease is discordant donor-recipient CMV serology (positive donor and negative recipient), which confers more than 50% risk of developing CMV disease if no prophylaxis is given. The use of highly potent antiviral agents for CMV prophylaxis in high-risk patients has changed the characteristics of CMV disease in this population. Other classical risk factors for CMV disease include acute graft rejection, the type of organ transplanted, coinfection with other herpesviruses and the type of immunosuppressive agents employed. New risk factors for this complication have recently been described, including variations in the CMV genotype between donor and recipient and genetic alterations in the recipient's innate immunity. The present review discusses classical risk factors and the latest findings reported on the development of CMV in organ transplant recipients.

Circulating ficolin-2 and ficolin-3 in normal pregnancy and pre-eclampsia

Ficolins are soluble molecules of the innate immune system that recognize carbohydrate molecules on microbial pathogens, apoptotic and necrotic cells. They act through two distinct routes: initiating the lectin pathway of complement activation and mediating a primitive opsonophagocytosis. In this study, we measured plasma levels of ficolin-2 and ficolin-3 in 60 pre-eclamptic patients, 60 healthy pregnant women and 59 healthy non-pregnant women by enzyme-linked immunosorbent assay (ELISA). Circulating levels of complement activation products (C4d, C3a, SC5b9), angiogenic factors (soluble fms-like tyrosine kinase-1, placental growth factor) and markers of endothelial activation (von Willebrand factor antigen), endothelial injury (fibronectin) and trophoblast debris (cell-free fetal DNA) were also determined. Plasma levels of ficolin-2 were significantly lower in healthy pregnant than in healthy non-pregnant women, while ficolin-3 levels did not differ significantly between the two groups. Furthermore, pre-eclamptic patients had significantly lower ficolin-2 and ficolin-3 concentrations than healthy non-pregnant and pregnant women. In the pre-eclamptic group, plasma ficolin-2 levels showed a significant positive correlation with serum placental growth factor (PlGF) concentrations and significant inverse correlations with serum levels of soluble fms-like tyrosine kinase-1 (sFlt-1), blood urea nitrogen and creatinine, serum lactate dehydrogenase activities, as well as with plasma VWF:antigen, fibronectin and cell-free fetal DNA concentrations. In conclusion, circulating levels of ficolin-2 are decreased in the third trimester of normal pregnancy. There is a further decrease in plasma ficolin-2 concentrations in pre-eclampsia, which might contribute to the development of the maternal syndrome of the disease through impaired removal of the trophoblast-derived material released into the maternal circulation by the hypoxic and oxidatively stressed pre-eclamptic placenta.

The role of complement in the early immune response to transplantation

The complement system is a key element of the innate immune system, and the production of complement components can be divided into central (hepatic) and peripheral compartments. Essential complement components such as C3 are produced in both of these compartments, but until recently the functional relevance of the peripheral synthesis of complement was unclear. Here, we review recent findings showing that local peripheral synthesis of complement in a transplanted organ is required for the immediate response of the donor organ to tissue stress and for priming alloreactive T cells that can mediate transplant rejection. We also discuss recent insights into the role of complement in antibody-mediated rejection, and we examine how new treatment strategies that take into account the separation of central and peripheral production of complement are expected to make a difference to transplant outcome.

Risk factors for infection after liver transplantation

Infection is a common cause of morbidity and mortality after liver transplantation. Risk factors relate to transplantation factors, donor and recipient factors. Transplant factors include ischaemia-reperfusion damage, amount of intra-operative blood transfusion, level and type of immunosuppression, rejection, and complications, prolonged intensive care stay with dialysis or ventilation, type of biliary drainage, repeat operations, re-transplantation, antibiotics, antiviral regimen, and environment. Donor risk factors include infection, prolonged intensive care stay, quality of the donor liver (e.g. steatosis), and viral status. For the recipient the most important are MELD score >30, malnutrition, renal failure, acute liver failure, presence of infection or colonisation, and immune status for viruses like cytomegalovirus. In recent years it has become clear that genetic polymorphisms in innate immunity, especially the lectin pathway of complement activation and in Toll-like receptors importantly contribute to the infection risk after liver transplantation. Therefore, the risk for infections after liver transplantation is a multifactorial problem and all factors need attention to reduce this risk.

Mannan-binding lectin-2 (MBL2) gene polymorphisms in prenatal and perinatal cytomegalovirus infections

Cytomegalovirus (CMV) is the leading cause of congenital infections among neonates. About 10% of newborns with such an infection have clinical symptoms at birth and about 1% of infected fetuses die due to developmental malformations. Mannan-binding lectin (MBL) is considered to be an important factor in innate immunity. Its deficiency is believed to predispose to various (including viral) infections. The aim of this study was to investigate the possible role of MBL2 gene polymorphisms in prenatal and perinatal CMV infections. The frequencies of MBL2 gene exon 1 mutations as well as MBL deficiency-associated variants (LXPA/O+O/O) among newborns with confirmed cytomegalovirus infection were not significantly lower than among non-infected individuals. The distribution of MBL2 haplotypes was similar between the groups studied. These data suggest MBL does not have a major influence on susceptibility to prenatal or perinatal CMV infections.