Safety and pharmacokinetics of plasma-derived mannose-binding lectin (MBL) substitution in children with chemotherapy-induced neutropaenia

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.

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.

Complement and phagocytes - A complicated interaction

Mohamed Daha and I share a common interest in innate immunity. Working in institutes only 25 miles away from each other, that meant ample opportunity and relevance for collaboration. And so we did. Moreover, we have both been members of boards and councils of Dutch national organizations, and we have also become good friends. In this short recollection, I look back on 40 years of common activities in complement research and friendship.

Multiple Infectious Complications in a Severely Injured Patient with Single Nucleotide Polymorphisms in Important Innate Immune Response Genes

Trauma is a major public health problem worldwide. Infectious complications, sepsis, and multiple organ dysfunction syndrome (MODS) remain important causes for morbidity and mortality in patients who survive the initial trauma. There is increasing evidence for the role of genetic variation in the innate immune system on infectious complications in severe trauma patients. We describe a trauma patient with multiple infectious complications caused by multiple micro-organisms leading to prolonged hospital stay with numerous treatments. This patient had multiple single nucleotide polymorphisms (SNPs) in the MBL2, MASP2, FCN2 and TLR2 genes, most likely contributing to increased susceptibility and severity of infectious disease.

L-Asparaginase lowers plasma antithrombin and mannan-binding-lectin levels: Impact on thrombotic and infectious events in children with acute lymphoblastic leukemia

BACKGROUND

L-asparaginase, a key therapeutic agent in the management of patients with acute lymphoblastic leukemia (ALL), dramatically impairs hepatic protein synthesis. We investigated the effects of prolonged exposure to L-asparaginase on antithrombin (AT), fibrinogen and mannan-binding-lectin (MBL) levels, and on the occurrence of thrombotic events (TE) and febrile neutropenia episodes (FN) in pediatric patients.

PROCEDURE

Protein levels were measured in 97 children during 30 weeks of chemotherapy with L-asparaginase and up to 1 year following remission. TE and FN episodes were recorded during this period.

RESULTS

Median AT level decreased from 0.96 IU/mL prior to treatment (range: 0.69-1.38) to 0.55 IU/mL (0.37-0.76) during therapy. Fibrinogen and MBL decreased from 3.18 g/L (1.29-7.28) and 1,177 ng/mL (57-5,343) to 1.56 g/L (0.84-2.13) and 193 ng/mL (57-544), respectively. All three proteins had recovered 1-4 weeks after L-asparaginase cessation. TE were reported in 22 (23%) patients. Of these, 11 occurred after a median of 10 administrations of L-asparaginase. Fifty-one FN were associated with infections, of which 36 occurred during treatment with L-asparaginase. Patients with low levels of MBL at diagnosis were at higher risk of FN associated with infections (RR = 1.59, 95%CI: 1.026-2.474). Both AT and MBL decreases were moderately correlated with fibrinogen (r = 0.51 and 0.58, respectively).

CONCLUSIONS

Children with ALL are exposed to significant decrease in AT, fibrinogen and MBL levels, and concomitant increased risk of thrombosis and FN with infection during L-asparaginase treatment. Measuring plasma levels of these liver-derived proteins could help predict the occurrence of adverse events.

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.

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.

The role of mannose-binding lectin in severe sepsis and septic shock

Severe sepsis and septic shock are a primary cause of death in patients in intensive care unit (ICU). Investigations upon genetic susceptibility profile to systemic complications during severe infections are a field of increasing scientific interest. Particularly when adaptive immune system is compromised or immature, innate immunity plays a key role in the immediate defense against invasive pathogens. Mannose-binding lectin (MBL) is a serum protein that recognizes a wide range of pathogenic microorganisms and activates complement cascade via the antibody-independent pathway. More than 30% of humans harbor mutations in MBL gene (MBL2) resulting in reduced plasmatic levels and activity. Increased risk of infection acquisition has been largely documented in MBL-deficient patients, but the real impact of this form of innate immunosuppression upon clinical outcome is not clear. In critically ill patients higher incidence and worse prognosis of severe sepsis/septic shock appear to be associated with low-producers haplotypes. However an excess of MBL activation might be also harmful due to the possibility of an unbalanced proinflammatory response and an additional host injury. Strategies of replacement therapies in critically ill patients with severe infections are under investigation but still far to be applied in clinical practice.

The lectin pathway and its implications in coagulation, infections and auto-immunity

PURPOSE OF REVIEW

To give a comprehensive overview of the recently published studies on the role of the lectin pathway in coagulation, infections and auto-immunity.

RECENT FINDINGS

We present the status quo picture of the lectin pathway, including the newly discovered member, MAp44 (a.k.a. MAP-1), which may act as a specific regulator of activation. On the functional side the focus is on the important discoveries of the connections between the coagulation system and mannose-binding lectin-associated serine proteases, newly discovered associations between the lectin pathway and infectious diseases, especially among neonates, the recent findings of the involvement of mannan-binding lectin and ficolins in auto-immune disorders, and novel therapeutic avenues. The involvement of the lectin pathway in ischemia-reperfusion injuries and transplantations is discussed elsewhere in this issue.

SUMMARY

The emerging picture of the lectin pathway is that it may play a role in the case of concomitant impairments of cellular and adaptive immunity, as seen in the case of premature infants, neonates, neutropenic cancer patients and the like. Considering the near-exponential increase in interest for the lectin pathway and its intricacies in recent years, the future of the field seems promising.

Serum Concentrations of Mannan-Binding Lectin (MBL) and MBL-Associated Serine Protease-2 and the Risk of Adverse Events in Pediatric Patients With Cancer and Fever in Neutropenia

BACKGROUND

It is unknown whether serum concentrations of mannan-binding lectin (MBL) and MBL-associated serine protease-2 (MASP-2) influence the risk of adverse events (AEs) in children with cancer presenting with fever in neutropenia (FN).

METHODS

Pediatric patients with cancer presenting with FN after non-myeloablative chemotherapy were observed in a prospective multicenter study. Mannan-binding lectin and MASP-2 were measured using commercially available enzyme-linked immunosorbent assay in serum taken at cancer diagnosis. Multiple FN episodes per patient were allowed. Associations of MBL and MASP-2 with AE in general, with bacteremia, and with serious medical complications (SMC) during FN were analyzed using mixed logistic regression.

RESULTS

Of 278 FN episodes, AE was reported in 84 (30%), bacteremia was reported in 42 (15%), and SMC was reported in 16 (5.8%). Median MBL was 2152 ng/mL (range, 7-10 060). It was very low (<100) in 11 (9%) patients, low (100-999) in 36 (29%) patients, and normal (≥1000) in 79 (63%) patients. Median MASP-2 was 410 ng/mL (range, 68-2771). It was low (<200) in 18 (14%) patients and normal in the remaining 108 (86%) patients. Mannan-binding lectin and MASP-2 were not significantly associated with AE or bacteremia. Normal versus low MBL was independently associated with a significantly higher risk of SMC (multivariate odds ratio, 12.8; 95% confidence interval, 1.01-163; P = .050).

CONCLUSIONS

Mannan-binding lectin and MASP-2 serum concentrations were not found to predict the risk to develop AEs or bacteremia during FN. Normal MBL was associated with an increased risk of SMC during FN. This finding, in line with earlier studies, does not support the concept of MBL supplementation in MBL-deficient children with cancer presenting with FN.

The emerging role of complement lectin pathway in trypanosomatids: molecular bases in activation, genetic deficiencies, susceptibility to infection, and complement system-based therapeutics

The innate immune system is evolutionary and ancient and is the pivotal line of the host defense system to protect against invading pathogens and abnormal self-derived components. Cellular and molecular components are involved in recognition and effector mechanisms for a successful innate immune response. The complement lectin pathway (CLP) was discovered in 1990. These new components at the complement world are very efficient. Mannan-binding lectin (MBL) and ficolin not only recognize many molecular patterns of pathogens rapidly to activate complement but also display several strategies to evade innate immunity. Many studies have shown a relation between the deficit of complement factors and susceptibility to infection. The recently discovered CLP was shown to be important in host defense against protozoan microbes. Although the recognition of pathogen-associated molecular patterns by MBL and Ficolins reveal efficient complement activations, an increase in deficiency of complement factors and diversity of parasite strategies of immune evasion demonstrate the unsuccessful effort to control the infection. In the present paper, we will discuss basic aspects of complement activation, the structure of the lectin pathway components, genetic deficiency of complement factors, and new therapeutic opportunities to target the complement system to control infection.

Mannose-binding lectin genotype influences frequency and duration of infectious complications in children with malignancy

Children with cancer receiving identical treatment differ in their experience of infection, suggesting that variations in immunity may influence susceptibility to infection. Studies of the influence of mannose-binding lectin (MBL), an important component of the innate immune system, in children with febrile neutropenia (FN) have yielded conflicting results. We examined the role of MBL in infection susceptibility in the largest cohort of children with cancer reported to date. MBL levels were measured and genotyping performed on children (≤16 y) receiving chemotherapy for cancer in London, UK. Clinical data from FN episodes were recorded prospectively. MBL status was assessed in 269 children; 513 episodes of FN were captured from 211 patients. Patients with MBL2 polymorphisms experienced more FN episodes than wildtype genotype (median 2 vs. 1, respectively; P = 0.074) and more episodes with documented infection (P = 0.045). Patients experiencing multiple FN episodes had lower MBL levels (P = 0.036). MBL genotype influenced duration of episode in some groups: high-risk MBL-deficient patients spent up to 5 nights longer/episode in hospital than equivalent wildtypes. These results indicate that MBL deficiency influences both susceptibility to and outcome of FN episodes and may be most important in those patients at higher risk of complications of FN.

Mannan-binding lectin in malignancy

Complement may play a dual role in cancer: it may contribute either to the development or to the inhibition of tumour growth. Its components may be candidate biomarkers facilitating the disease detection, its progress or effectiveness of therapy. Additionally, complement deficiencies may increase the risk of infections and contribute to the higher mortality, especially in patients undergoing aggressive chemotherapy. In this paper, possible cancer associations of one of the factors activating complement via the lectin pathway, mannan-binding lectin (MBL), are discussed.

Birds, babies and blood

This is an autobiographical review describing the author's career in immunology research and summarizing his current understanding of the areas involved. Contributions to autoimmunity, immune deficiency, transfusion immunology, HLA-disease associations, reproductive immunology, cellular therapies, and innate immunity are included; also discussion of medical research ethics and various research-related activities.

MASP interactions with plasma-derived MBL

The interaction of mannan-binding lectin (MBL) with its associated serine proteases (MASPs) was investigated using recombinant (r) MBL, plasma-derived (pd) MBL, rMASP-3 and rMAp19. When mixed with MBL-deficient serum, rMBL and pdMBL associated with free MASP-2 to (re)gain complement-activating activity. MASPs already associated with pdMBL did not exchange with rMASP-3 or rMAp19, which bound to non-overlapping sites on MBL. Thus, rMASP-3 and rMAp19 bound to free available sites on rMBL and pdMBL. These results have important implications for the therapeutic use of MBL preparations.

A pilot study of host genetic variants associated with influenza-associated deaths among children and young adults

Low-producing MBL2 genotypes may have increased risk for MRSA co-infection.

We compared the prevalence of 8 polymorphisms in the tumor necrosis factor and mannose-binding lectin genes among 105 children and young adults with fatal influenza with US population estimates and determined in subanalyses whether these polymorphisms were associated with sudden death and bacterial co-infection among persons with fatal influenza. No differences were observed in genotype prevalence or minor allele frequencies between persons with fatal influenza and the reference sample. Fatal cases with low-producing MBL2 genotypes had a 7-fold increased risk for invasive methicillin-resistant Staphylococcus aureus (MRSA) co-infection compared with fatal cases with high- and intermediate-producing MBL2 genotypes (odds ratio 7.1, 95% confidence interval 1.6–32.1). Limited analysis of 2 genes important to the innate immune response found no association between genetic variants and fatal influenza infection. Among children and young adults who died of influenza, low-producing MBL2 genotypes may have increased risk for MRSA co-infection.

Mannan-binding lectin deficiency - Good news, bad news, doesn't matter?

Mannan-binding lectin (MBL) deficiency has been classified as a commonly occurring immune disorder, affecting approximately 30% of the human population. MBL, being part of the innate immune system, supports the recognition of infectious pathogens by binding to carbohydrate moieties expressed on microorganisms and activates the lectin pathway of the complement system. MBL2 gene polymorphisms are associated with quantitative and qualitative MBL abnormalities in the serum. The clinical impact of MBL deficiency and its association to a wide variety of diseases has been extensively studied. The picture is puzzling as the studies suggest a detrimental or beneficial or no impact of low or high MBL serum levels on disease susceptibility. In this review we attempt to extract what is relevant from the literature and address controversial issues. We finally suggest that a comprehensive understanding of the role of MBL in human diseases requires considering its context-dependency.

Decreased efferocytosis and mannose binding lectin in the airway in bronchiolitis obliterans syndrome

BACKGROUND

Mannose binding lectin (MBL) is a key mediator of both innate immunity and efferocytosis (phagocytosis of apoptotic cells) in the airway. Defective efferocytosis results in a net increase in apoptotic material that can undergo secondary necrosis, leading to tissue damage and chronic inflammation. We have shown reduced MBL and efferocytosis in other chronic inflammatory lung diseases; we therefore hypothesized that reduced MBL and efferocytosis in the airways may be a determinant of bronchiolitis obliterans syndrome (BOS) after lung transplantation.

METHODS

We investigated MBL (enzyme-linked immunosorbent assay [ELISA]), MBL-mediated complement deposition (UC4, ELISA), and efferocytosis of apoptotic bronchial epithelial cells (flow cytometry) in bronchoalveolar lavage (BAL) and peripheral blood from 75 lung transplant recipients, comprising 16 with stable graft function, 34 stable with proven infection, 25 with BOS, and 14 healthy controls.

RESULTS

In plasma, MBL levels were highly variable (0-17.538 μg/ml), but increased in infected patients vs control (p = 0.09) or stable groups (p = 0.003). There was a similar increase in UC4 in infected patients and a significant correlation between MBL and UC4. There was no correlation between MBL and time after transplant. In BAL, MBL levels were less variable (0-73.3 ng/ml) and significantly reduced in patients with BOS vs controls and stable groups. Efferocytosis was significantly reduced in the BOS group vs control and stable groups (mean [SEM] control, 20% [1.3%]; stable, 20.5% [2.5%]; infected, 17.3% [2.8%]; BOS, 11.3% [1.5%], p = 0.04).

CONCLUSIONS

Low levels of MBL in the airway may play a role in reduced efferocytosis, subsequent tissue damage, and BOS after lung transplantation.

Complement deficiency states and associated infections

A major function of the immune system is to protect the host from microbial infections. The complement system plays important roles in both the innate and the adaptive immune defense and also acts as a bridge between these arms of immunity. This is obvious from complement deficiencies which in varying degree, depending on which factor is missing, are associated with increased infection susceptibility and also increased risk for other, mainly autoimmune diseases. Genetically determined deficiencies are described for almost all complement proteins but the consequences show a wide variation. Here the genetic defects and molecular abnormalities in complement deficient persons, related clinically relevant infections and the options for prevention and therapy are reviewed. The roles of complement in host defense against common infections are also discussed.

Mannan-binding lectin and healing of a radiation-induced chronic ulcer--a case report on mannan-binding lectin replacement therapy

Mannan-binding lectin is an important component of innate immunity, and insufficiency is associated with several clinical disorders. Recently, experimental replacement therapy with plasma-derived mannan-binding lectin has become an option. The current article presents the case of a patient with an insufficient level of mannan-binding lectin and a chronic radiation-induced ulcer following the treatment of breast cancer. After 15 months of initially conservative treatment and thereafter plastic surgery, the healing was still impaired with necrosis in the periphery of the ulcer. Immunological work-up of the patient revealed pronounced insufficiency of mannan-binding lectin. Following a 6-week experimental intravenous treatment with mannan-binding lectin purified from human plasma, that is, 0.2-0.3 mg mannan-binding lectin per kg body weight twice a week, the defect was completely healed. We suggest that deficiency of mannan-binding lectin can explain cases of otherwise unexplained impaired healing, and that replacement therapy is considered in such cases.

Infections of people with complement deficiencies and patients who have undergone splenectomy

The complement system comprises several fluid-phase and membrane-associated proteins. Under physiological conditions, activation of the fluid-phase components of complement is maintained under tight control and complement activation occurs primarily on surfaces recognized as "nonself" in an attempt to minimize damage to bystander host cells. Membrane complement components act to limit complement activation on host cells or to facilitate uptake of antigens or microbes "tagged" with complement fragments. While this review focuses on the role of complement in infectious diseases, work over the past couple of decades has defined several important functions of complement distinct from that of combating infections. Activation of complement in the fluid phase can occur through the classical, lectin, or alternative pathway. Deficiencies of components of the classical pathway lead to the development of autoimmune disorders and predispose individuals to recurrent respiratory infections and infections caused by encapsulated organisms, including Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae. While no individual with complete mannan-binding lectin (MBL) deficiency has been identified, low MBL levels have been linked to predisposition to, or severity of, several diseases. It appears that MBL may play an important role in children, who have a relatively immature adaptive immune response. C3 is the point at which all complement pathways converge, and complete deficiency of C3 invariably leads to severe infections, including those caused by meningococci and pneumococci. Deficiencies of the alternative and terminal complement pathways result in an almost exclusive predisposition to invasive meningococcal disease. The spleen plays an important role in antigen processing and the production of antibodies. Splenic macrophages are critical in clearing opsonized encapsulated bacteria (such as pneumococci, meningococci, and Escherichia coli) and intraerythrocytic parasites such as those causing malaria and babesiosis, which explains the fulminant nature of these infections in persons with anatomic or functional asplenia. Paramount to the management of patients with complement deficiencies and asplenia is educating patients about their predisposition to infection and the importance of preventive immunizations and seeking prompt medical attention.

Impact of mannose-binding lectin insufficiency on the course of cystic fibrosis: A review and meta-analysis

Mannose-binding lectin (MBL) is an innate immune protein produced by the liver. MBL binds to glycoconjugates containing mannose, fucose or N-acetylglucosamine that are present in a wide variety of bacteria, viruses and fungi. Upon binding, MBL may active the lectin pathway of complement or directly opsonize organisms to enhance phagocytosis. MBL is primarily a serum protein but accumulates in the lung during acute inflammation. Recent evidence suggests an important role for MBL in a variety of infectious disorders. Cystic fibrosis (CF) is a multisystem disease caused by mutations in the gene encoding the CF transmembrane regulator (CFTR). The course of CF lung disease is highly variable even in patients with the same CFTR genotype, suggesting that other modulator genes are important for prognosis. MBL has been proposed as a possible modulator of clinical severity in CF. In this review and meta-analysis, we found that MBL2 genotypes associated with MBL insufficiency were associated with earlier acquisition of Pseudomonas aeruginosa (P < 0.0001), reduced pulmonary function among adult patients (P < 0.0001 for forced expiratory volume), and an increased rate of death or requirement for lung transplantation (odds ratio 3.69; P = 0.02). The available evidence therefore suggests that MBL insufficiency is associated with the severity of CF lung disease. The possible future prophylactic or therapeutic application of MBL replacement is discussed.

Effects of mannose-binding lectin polymorphisms on irinotecan-induced febrile neutropenia

OBJECTIVE

Mannose-binding lectin (MBL) is important in the innate immune response. MBL2 gene polymorphisms affect MBL expression, and genotypes yielding low MBL levels have been associated with an elevated risk for infections in hematological cancer patients undergoing chemotherapy. However, these reported associations are inconsistent, and data on patients with solid tumors are lacking. Here, we investigated the effects of MBL2 genotypes on irinotecan-induced febrile neutropenia in patients with solid tumors.

PATIENTS AND METHODS

Irinotecan-treated patients were genotyped for the MBL2 gene. Two promoter (-550 H/L and -221 X/Y) and three exon polymorphisms (52 A/D, 54 A/B, and 57 A/C) were determined, together with known risk factors for irinotecan-induced toxicity. Neutropenia and febrile neutropenia were recorded during the first course.

RESULTS

Of the 133 patients, 28% experienced severe neutropenia and 10% experienced febrile neutropenia. No associations were found between exon polymorphisms and febrile neutropenia. However, patients with the H/H promoter genotype, associated with high MBL levels, experienced significantly more febrile neutropenia than patients with the H/L and L/L genotypes (20% versus 13% versus 5%). Moreover, patients with the HYA haplotype encountered significantly more febrile neutropenia than patients without this high MBL-producing haplotype (16% versus 4%). In the subgroup with wild-type exon polymorphisms (A/A), patients with the high MBL promoter phenotype had the highest incidence of febrile neutropenia, regardless of known risk factors.

CONCLUSION

Patients with high MBL2 promoter genotypes and haplotypes seem more at risk for developing febrile neutropenia. If confirmed, these preliminary findings may contribute to more individualized approaches of irinotecan treatment.

Lectin complement pathway gene profile of donor and recipient determine the risk of bacterial infections after orthotopic liver transplantation

Infectious complications after orthotopic liver transplantation (OLT) are a major clinical problem. The lectin pathway of complement activation is liver-derived and a crucial effector of the innate immune defense against pathogens. Polymorphisms in lectin pathway genes determine their functional activity. We assessed the relationship between these polymorphic genes and clinically significant bacterial infections, i.e., sepsis, pneumonia, and intra-abdominal infection, and mortality within the first year after OLT, in relation to major risk factors in two cohorts from different transplant centers. Single-nucleotide polymorphisms in the mannose-binding lectin gene (MBL2), the ficolin-2 gene (FCN2), and the MBL-associated serine protease gene (MASP2) of recipients and donors were determined. Recipients receiving a donor liver in the principal cohort with polymorphisms in all three components i.e., MBL2 (XA/O; O/O), FCN2+6359T, and MASP2+371A, had a cumulative risk of an infection of 75% as compared to 18% with wild-type donor livers (P = 0.002), an observation confirmed in the second cohort (P = 0.04). In addition, a genetic (mis)match between donor and recipient conferred a two-fold higher infection risk for each separate gene. Multivariate Cox analysis revealed a stepwise increase in infection risk with the lectin pathway gene profile of the donor (hazard ratio = 4.52; P = 8.1 x 10(-6)) and the donor-recipient (mis)match genotype (hazard ratio = 6.41; P = 1.9 x 10(-7)), independent from the other risk factors sex and antibiotic prophylaxis (hazard ratio > 1.7 and P < 0.02). Moreover, patients with a lectin pathway gene polymorphism and infection had a six-fold higher mortality (P = 0.9 x 10(-8)), of which 80% was infection-related.

CONCLUSION

Donor and recipient gene polymorphisms in the lectin complement pathway are major determinants of the risk of clinically significant bacterial infection and mortality after OLT.