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

Mannose-binding lectin gene polymorphism and the susceptibility of sepsis: A meta-analysis

Objective

To assess the association between the Mannose-binding lectin (MBL) gene polymorphism and the susceptibility to sepsis using a meta-analysis.

Methods

The publications were searched on PubMed, Embase, and Web of Science databases up to December 1, 2019 for relevant literature.

Results

A total of 32 studies (21 adult and 11 pediatric studies) were selected for analysis. Overall, in the three models of MBL +54 A/B gene polymorphisms, namely the dominant model BB + AB vs. AA ( p = 0.03), the recessive model BB vs. AB + AA ( p < 0.00001), and the allele model B vs. A ( p = 0.04), MBL +54 A/B was significantly related to the risk of sepsis. In the adult group, the MBL A/O gene polymorphism was associated with the risk of sepsis in the dominant model AO + OO vs. AA ( p = 0.006) as well as in the allele model O vs. A ( p = 0.04). The MBL +54 A/B gene polymorphism was significantly related to the risk of sepsis in the recessive model and, therefore, may increase the risk of sepsis. In the pediatric group, no polymorphic loci were significantly associated with sepsis in any of the three models. The results of the publication bias test demonstrated no publication bias in an unadjusted estimate of the relationship between MBL A/O and −211Y/X gene polymorphism and sepsis.

Conclusions

The polymorphisms of MBL that are related to the occurrence of sepsis are primarily A/O and +54 A/B, while −221Y/X and −550H/L have no clear relationship with the susceptibility of sepsis in various age groups or different models.

Polymorphisms of the FCN2 Gene 3'UTR Region and Their Clinical Associations in Preterm Newborns

Ficolin-2 is regarded as an important innate immunity factor endowed with both lectin (carbohydrate recognition) qualities and ability to induce complement activation. The aim of this study was to investigate the association of the FCN2 3'-untranslated region (3'UTR) polymorphisms with ficolin-2 expression and perinatal complications in preterm neonates. The sequencing analysis allowed us to identify six 3'UTR polymorphisms with minor allele frequency (MAF) >1%: rs4521835, rs73664188, rs11103564, rs11103565, rs6537958 and rs6537959. Except for rs4521835, all adhered to Hardy-Weinberg expectations. Moreover, rs6537958 and rs6537959 were shown to be in perfect linkage disequilibrium (LD) with nine other genetic polymorphisms: rs7040372, rs7046516, rs747422, rs7847431, rs6537957, rs6537960, rs6537962, rs11462298 and rs7860507 together stretched on a distance of 1242 bp and very high LD with rs11103565. The 3'UTR region was shown to bind nuclear extract proteins. The polymorphisms at rs4521835 and rs73664188 were found to influence serum ficolin-2 concentration significantly. All polymorphisms identified create (together with exon 8 polymorphism, rs7851696) two haplotype blocks. Among 49 diplotypes (D1-D49) created from rs7851696 (G>T), rs4521835 (T>G), rs73664188 (T>C), rs11103564 (T>C), rs11103565 (G>A) and rs6537959 (T>A), twenty two occurred with frequency >1%. Two diplotypes: D13 (GTTTGT/GGTCGT) and D10 (GTTTGT/GGTCGA), were significantly more frequent among preterm neonates with early onset of infection and pneumonia, compared with newborns with no infectious complications (OR 2.69 and 2.81, respectively; both p<0.05). The minor (C) allele at rs73664188 was associated with an increased risk of very low (≤1500 g) birthweight (OR=1.95, p=0.042) but was associated with the opposite effect at rs11103564 (OR=0.11, p=0.005).

Genetics of Immune Disease in the Horse

Host defenses against infection by viruses, bacteria, fungi, and parasites are critical to survival. It has been estimated that upwards of 7% of the coding genes of mammals function in immunity and inflammation. This high level of genomic investment in defense has resulted in an immune system characterized by extraordinary complexity and many levels of redundancy. Because so many genes are involved with immunity, there are many opportunities for mutations to arise that have negative effects. However, redundancy in the mammalian defense system and the adaptive nature of key immune mechanisms buffer the untoward outcomes of many such deleterious mutations.

Transcriptome analysis of body wall reveals growth difference between the largest and smallest individuals in the pure and hybrid populations of Apostichopus japonicus

Long-term inbreeding of sea cucumber has resulted in a decrease in its growth rate, which has severely affected yield and economic efficiency. In this study, three Apostichopus japonicus families were constructed and screened into the weight of smallest and largest, which included Russian, Chinese, and their hybrids (RC). We examined the transcriptional profiles of hybrid (RC) and purebred (CC and RR). A total of 49.69 Gb clean reads were obtained, and the Q30 base percentage was above 90.47%. A total of 5191 novel genes were discovered, of which 2592 genes were annotated. Differentially expressed genes (DEGs) were identified, and functional annotation and enrichment analysis were performed. Approximately 1874 DEGs were screened in the Chinese sea cucumber (CC) difference group; 2591 DEGs were obtained in the hybrid sea cucumber difference group (RC), and 3006 DEGs were obtained in the Russian sea cucumber difference group (RR). In Gene Ontology (GO) analysis, highest DEG enrichment was observed for the functional categories of cellular process and metabolic process. In terms of cellular components, DEG enrichment was observed in cell part, cell; for molecular function, DEG enrichment was detected in catalytic activity, binding, hydrolase activity, transferase activity. According to the differential expression analysis, we found that 15 heat shock protein (HSP) genes that have the same expression trends, which were upregulated in the smallest weight of three sea cucumber lines. In addition, COG analysis of defense genes was conducted. All defense genes (ATP-binding cassette transporters (ABCs), multidrug resistance protein (MRPs), and beta-lactamase) showed the same expression trend, which was significantly upregulated in smallest individuals compared to that of largest individuals in RC lines, which implied the smallest individuals are exposed to more pressure during growth. These results may lead to the smallest individuals showing slow growth. Additionally, we selected 12 DEGs to validate the result by qPCR. Those DEGs were included in growth-related and resistance genes. Sequencing of the A. japonicus transcriptome improves our understanding of the transcriptional regulatory apparatus that controls individual development and growth.

Effects of immunoadsorption combined with membrane filtration on complement markers - results of a randomized, controlled, crossover study

The complement system has been implicated in several kidney diseases, such as antibody-mediated rejection after kidney transplantation. Antibody-depletion techniques allow successful ABO- and/or HLA-incompatible transplantation. Considering the IgG removal, the use of semi-selective immunoadsorption (IA) has been advocated. However, because of results on incomplete IgM depletion, the adjunctive use of membrane filtration (MF) has been proposed to enhance the removal of macromolecules and to interfere with complement activation. This secondary endpoint analysis of a recently published randomized, controlled, cross-over trial was designed to investigate the effect of combined treatment IA + MF compared to IA alone on complement depletion. Two treatment sequences, a single session of IA + MF followed by IA (and vice versa), were analyzed with regard to C5b-9, properdin, and mannose-binding lectin (MBL) levels. Neither IA alone nor IA + MF provoked complement activation as demonstrated by stable low levels of C5b-9 after the procedure as compared to the previous. The combined treatment substantially lowered properdin (77% vs. 26% reduction, P < 0.0001) as well as MBL concentrations (81% vs. 11% reduction, P < 0.0001). Recovery of properdin and MBL levels appears to be longer after IA alone compared to IA + MF. Depletion of properdin and MBL levels may have potential clinical implications in the setting of kidney transplantation.

Ficolins and the Recognition of Pathogenic Microorganisms: An Overview of the Innate Immune Response and Contribution of Single Nucleotide Polymorphisms

Ficolins are innate pattern recognition receptors (PRR) and play integral roles within the innate immune response to numerous pathogens throughout the circulation, as well as within organs. Pathogens are primarily removed by direct opsonisation following the recognition of cell surface carbohydrates and other immunostimulatory molecules or via the activation of the lectin complement pathway, which results in the deposition of C3b and the recruitment of phagocytes. In recent years, there have been a number of studies implicating ficolins in the recognition and removal of numerous bacterial, viral, fungal, and parasitic pathogens. Moreover, there has been expanding evidence highlighting that mutations within these key immune proteins, or the possession of particular haplotypes, enhance susceptibility to colonization by pathogens and dysfunctional immune responses. This review will therefore encompass previous knowledge on the role of ficolins in the recognition of bacterial and viral pathogens, while acknowledging the recent advances in the immune response to fungal and parasitic infections. Additionally, we will explore the various genetic susceptibility factors that predispose individuals to infection.

Identification of genetic variation in equine collagenous lectins using targeted resequencing

Collagenous lectins are a family of soluble pattern recognition receptors that play an important role in innate immune resistance to infectious disease. Through recognition of carbohydrate motifs on the surface of pathogens, some collagenous lectins can activate the lectin pathway of complement, providing an effective means of host defense. Genetic polymorphisms in collagenous lectins have been shown in several species to predispose animals to a variety of infectious diseases. Infectious diseases are an important cause of morbidity in horses, however little is known regarding the role of equine collagenous lectins. Using a high-throughput, targeted re-sequencing approach, the relationship between genetic variation in equine collagenous lectin genes and susceptibility to disease was investigated. DNA was isolated from tissues obtained from horses submitted for post-mortem examination. Animals were divided into two populations, those with infectious or autoinflammatory diseases (n = 37) and those without (n = 52), and then subdivided by dominant pathological process for a total of 21 pools, each containing 4-5 horses. DNA was extracted from each horse and pooled in equimolar amounts, and the exons, introns, upstream (approximately 50 kb) and downstream (approximately 3 kb) regulatory regions for the 11 equine collagenous lectin genes and related MASP genes were targeted for re-sequencing. A custom target capture kit was used to prepare a sequencing library, which was sequenced on an Illumina MiSeq. After implementing quality control filters, 4559 variants were identified. Of these, 92 were present in the coding regions (43 missense, 1 nonsense, and 48 synonymous), 1414 in introns, 3029 in the upstream region, and 240 in the downstream region. In silico analysis of the missense short nucleotide variants identified 12 mutations with potential to disrupt collagenous lectin protein structure or function, 280 mutations located within predicted transcription factor binding sites, and 95 mutations located within predicted microRNA binding elements. Analysis of allelic association identified 113 mutations that segregated between the infectious/autoinflammatory and non-infectious populations. The variants discovered in this experiment represent potential genetic contributors to disease susceptibility of horses, and will serve as candidates for further population-level genotyping. This study contributes to the growing body of evidence that pooled, high-throughput sequencing is a viable strategy for cost-effective variant discovery.

Effects of MASP2 haplotypes and MASP-2 levels in hepatitis C-infected patients

Mannan-binding lectin (MBL) and MBL-associated serine protease 2 (MASP-2) are components of the lectin pathway, which activate the complement system after binding to the HCV structural proteins E1 and E2. We haplotyped 11 MASP2 polymorphisms in 103 HCV patients and 205 controls and measured MASP-2 levels in 67 HCV patients and 77 controls to better understand the role of MASP-2 in hepatitis C susceptibility and disease severity according to viral genotype and fibrosis levels. The haplotype block MASP2*ARDP was associated with protection against HCV infection (OR = 0.49, p = .044) and lower MASP-2 levels in controls (p = .021), while haplotype block AGTDVRC was significantly increased in patients (OR = 7.58, p = .003). MASP-2 levels were lower in patients than in controls (p < .001) and in patients with viral genotype 1 or 4 (poor responders to treatment) than genotype 3 (p = .022) and correlated inversely with the levels of alkaline phosphatase, especially in individuals with fibrosis 3 or 4 (R = -.7, p = .005). MASP2 gene polymorphisms modulate basal gene expression, which may influence the quality of complement response against HCV. MASP-2 levels decrease during chronic disease, independently of MASP2 genotypes, most probably due to consumption and attenuation mechanisms of viral origin and by the reduced liver function, the site of MASP-2 production.

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.

A dual role for Mannan-binding lectin-associated serine protease 2 (MASP-2) in HIV infection

BACKGROUND

Mannan-binding lectin (MBL) - associated serine protease 2 (MASP-2) co-activates the lectin pathway of complement in response to several viral infections. The quality of this response partly depends on MASP2 gene polymorphisms, which modulate MASP-2 function and serum levels. In this study we investigated a possible role of MASP2 polymorphisms, MASP-2 serum levels and MBL-mediated complement activation in the susceptibility to HIV/AIDS and HBV/HCV coinfection.

METHODS

A total of 178 HIV patients, 89 (50%) coinfected with HBV/HCV, 51.7% female, average age 40 (12-73) years, and 385 controls were evaluated. MASP-2 levels and MBL-driven complement activation were evaluated by enzyme-linked immunosorbent assay and 11 MASP2 polymorphisms from the promoter to the last exon were haplotyped using multiplex sequence-specific PCR.

RESULTS

Genotype distribution was in Hardy-Weinberg equilibrium and differed between HIV+ patients and controls (P=0.030), irrespective of HBV or HCV coinfection. The p.126L variant, which was associated with MASP-2 levels <200ng/mL (OR=5.0 [95%CI=1.3-19.2] P=0.019), increased the susceptibility to HIV infection (OR=5.67 [95%CI=1.75-18.33], P=0.004) and to HIV+HBV+ status (OR=6.44 [95%CI=1.69-24.53, P=0.006). A similar association occurred with the ancient haplotype harboring this variant, AGCDV (OR=2.35 [95%CI=1.31-4.23], P=0.004). On the other hand, p.126L in addition to other variants associated with low MASP-2 levels-p.120G, p.377A and p.439H, presented a protective effect against AIDS (OR=0.25 [95%CI=0.08-0.80], P=0.020), independently of age, sex, hepatic function and viral load. MASP-2 serum levels were lower in HIV+ and HIV+HBV+ patients than in controls (P=0.0004). Among patients, MASP-2 levels were higher in patients with opportunistic diseases (P=0.001) and AIDS (P=0.004). MASP-2 levels correlated positively with MBL/MASP2-mediated C4 deposition (r=0.29, P=0.0002) and negatively with CD4+ cell counts (r=-0.21, P=0.018), being related to decreased CD4+ cell counts (OR=5.8 [95%CI=1.23-27.5, P=0.026).

CONCLUSIONS

Genetically determined MASP-2 levels seem to have a two-edge effect in HIV and probably HCV/HBV coinfection, whereas low levels increase the susceptibility to infection, but on the other side protects against AIDS.

Activated Complement Factors as Disease Markers for Sepsis

Sepsis is a leading cause of death in the United States and worldwide. Early recognition and effective management are essential for improved outcome. However, early recognition is impeded by lack of clinically utilized biomarkers. Complement factors play important roles in the mechanisms leading to sepsis and can potentially serve as early markers of sepsis and of sepsis severity and outcome. This review provides a synopsis of recent animal and clinical studies of the role of complement factors in sepsis development, together with their potential as disease markers. In addition, new results from our laboratory are presented regarding the involvement of the complement factor, mannose-binding lectin, in septic shock patients. Future clinical studies are needed to obtain the complete profiles of complement factors/their activated products during the course of sepsis development. We anticipate that the results of these studies will lead to a multipanel set of sepsis biomarkers which, along with currently used laboratory tests, will facilitate earlier diagnosis, timely treatment, and improved outcome.

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.

Single nucleotide polymorphism creating a variable upstream open reading frame regulates glucocorticoid receptor expression

The glucocorticoid and mineralocorticoid receptors are known to play a crucial role in cellular responses to acute and chronic stress conditions. However, the influence of genetic variants and regulatory mechanisms within the glucocorticoid and mineralocorticoid receptor genes NR3C1 and NR3C2 is still incompletely understood. We therefore investigated putative upstream open reading frames, a motif regulating gene expression, from the 5' untranslated regions of the predominant human glucocorticoid receptor gene NR3C1 isoform alpha variant 1 and from the human mineralocorticoid receptor NR3C2 variants 1 and 2. The in silico analysis displayed one SNP (rs10482612), being present heterozygously in about 1.2% of the world population and 1.8% of the European population (according to the NCBI database), whose minor allele 'A' creates an upstream start codon. Our functional analysis performed by reporter gene assay and quantitative real-time PCR confirmed that the minor allele 'A' of the SNP rs10482612 can indeed alter protein activity of the subsequent gene during baseline conditions and cellular stress by creating a functional uORF in the 5'UTR of the NR3C1 transcript variant 1.

Prediction of multiple infections after severe burn trauma: a prospective cohort study

OBJECTIVE

To develop predictive models for early triage of burn patients based on hypersusceptibility to repeated infections.

BACKGROUND

Infection remains a major cause of mortality and morbidity after severe trauma, demanding new strategies to combat infections. Models for infection prediction are lacking.

METHODS

Secondary analysis of 459 burn patients (≥16 years old) with 20% or more total body surface area burns recruited from 6 US burn centers. We compared blood transcriptomes with a 180-hour cutoff on the injury-to-transcriptome interval of 47 patients (≤1 infection episode) to those of 66 hypersusceptible patients [multiple (≥2) infection episodes (MIE)]. We used LASSO regression to select biomarkers and multivariate logistic regression to built models, accuracy of which were assessed by area under receiver operating characteristic curve (AUROC) and cross-validation.

RESULTS

Three predictive models were developed using covariates of (1) clinical characteristics; (2) expression profiles of 14 genomic probes; (3) combining (1) and (2). The genomic and clinical models were highly predictive of MIE status [AUROCGenomic = 0.946 (95% CI: 0.906-0.986); AUROCClinical = 0.864 (CI: 0.794-0.933); AUROCGenomic/AUROCClinical P = 0.044]. Combined model has an increased AUROCCombined of 0.967 (CI: 0.940-0.993) compared with the individual models (AUROCCombined/AUROCClinical P = 0.0069). Hypersusceptible patients show early alterations in immune-related signaling pathways, epigenetic modulation, and chromatin remodeling.

CONCLUSIONS

Early triage of burn patients more susceptible to infections can be made using clinical characteristics and/or genomic signatures. Genomic signature suggests new insights into the pathophysiology of hypersusceptibility to infection may lead to novel potential therapeutic or prophylactic targets.